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Journa C A L I F O R N I A

D E N TA L

June 2021 Ectodermal Dysplasia Computer-Engineered Dentures Denture Aesthetics Digital Prosthodontics and Simulation

A S S O C I AT I O N

Merging Well-Founded Principles With New Trends in Prosthodontics Evangelos Rossopoulos, DDS

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Vol 49    Nº 6


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June 2021

C D A J O U R N A L , V O L 4 9 , Nº 6

d e pa r t m e n t s

365 The Associate Editor/Start at the Beginning 367 Impressions 407

RM Matters/Workers’ Compensation: Proper Reporting Protocols Protect Your Practice and Employees

411 Regulatory Compliance/Regulatory Compliance Tips for New Dentists 414 Tech Trends

f e at u r e s

371 Merging Well-Founded Principles With New Trends in Prosthodontics An introduction to the issue.

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Evangelos Rossopoulos, DDS

373 Interdisciplinary Approach for the Oral Rehabilitation of an Ectodermal Dysplasia Patient C.E. Credit The purpose of this report was to describe the multidisciplinary dental treatment approach of an adult patient diagnosed with ectodermal dysplasia. Konstantinos Chochlidakis, DDS, MS; Evangelia Lampraki, DDS; Maria Gabriela Carranza, DDS; Carlo Ercoli, DDS, MBA; Theocharis Nikellis, DMD; and Alexandra Tsigarida, DDS, MS

381 Computer-Engineered Complete Dentures: Where Are We Now? A Review The purpose of this review article was to evaluate the current status of computerengineered complete dentures by conducting a search of related literature. Sarah Bukhari, BDS, MS; Abdulaziz A. Alzaid, BDS, MS; Raneem Alduraiby, BDS; Periklis Proussaefs, DDS, MS; and Mathew T. Kattadiyil, BDS, MDS, MS

393 Complete-Denture Aesthetics Revisited in the Digital Age The objective of this review is to elucidate the principles of complete denture aesthetics and establish a rationale for a digital workflow for chairside arrangement of artificial teeth. Steven J. Sadowsky, DDS

401 The New Age of Prosthodontics Education: Digital Prosthodontics and Simulation This article reviews the features of an augmented simulation device being piloted at the University of California, Los Angeles, School of Dentistry. Kumar C. Shah, BDS, MS; Brittany A. Kane, DMD; and Pamela A. Lloren, DDS

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published by the California Dental Association 1201 K St., 14th Floor Sacramento, CA 95814 800.232.7645 cda.org

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D E N TA L

Management Peter A. DuBois Executive Director Carrie E. Gordon Chief Strategy Officer Alicia Malaby Communications Director

Editorial Kerry K. Carney, DDS, CDE Editor-in-Chief Kerry.Carney@cda.org Ruchi K. Sahota, DDS, CDE Associate Editor Brian K. Shue, DDS, CDE Associate Editor

Volume 49 Number 6 June 2021

A S S O C I AT I O N

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The Journal of the California Dental Association (ISSN 1942-4396) is published monthly by the California Dental Association, 1201 K St., 14th Floor, Sacramento, CA 95814, 916.554.5950. The California Dental Association holds the copyright for all articles and artwork published herein.

Journal of the California Dental Association Editorial Board Charles N. Bertolami, DDS, DMedSc,Herman Robert Fox dean, NYU College of Dentistry, New York Steven W. Friedrichsen, DDS,professor and dean, Western University of Health Sciences College of Dental Medicine, Pomona, Calif. Mina Habibian, DMD, MSc, PhD,associate professor of clinical dentistry, Herman Ostrow School of Dentistry of USC, Los Angeles Robert Handysides, DDS,dean and associate professor, department of endodontics, Loma Linda University School of Dentistry, Loma Linda, Calif. Bradley Henson, DDS, PhD, associate dean for research and biomedical sciences and associate professor, Western University of Health Sciences College of Dental Medicine, Pomona, Calif. Paul Krebsbach, DDS, PhD,dean and professor, section of periodontics, University of California, Los Angeles, School of Dentistry Jayanth Kumar, DDS, MPH,state dental director, Sacramento, Calif. Lucinda J. Lyon, BSDH, DDS, EdD,associate dean, oral health education, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco Nader A. Nadershahi, DDS, MBA, EdD,dean, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco Francisco Ramos-Gomez, DDS, MS, MPH,professor, section of pediatric dentistry and director, UCLA Center for Children’s Oral Health, University of California, Los Angeles, School of Dentistry Michael Reddy, DMD, DMSc,dean, University of California, San Francisco, School of Dentistry

The Journal of the California Dental Association is published under the supervision of CDA’s editorial staff. Neither the editorial staff, the editor, nor the association are responsible for any expression of opinion or statement of fact, all of which are published solely on the authority of the author whose name is indicated. The association reserves the right to illustrate, reduce, revise or reject any manuscript submitted. Articles are considered for publication on condition that they are contributed solely to the Journal of the California Dental Association. The association does not assume liability for the content of advertisements, nor do advertisements constitute endorsement or approval of advertised products or services.

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Harold Slavkin,DDS, dean and professor emeritus, division of biomedical sciences, Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of USC, Los Angeles

Richard W. Valachovic, DMD, MPH,president emeritus, American Dental Education Association, Washington, D.C.


Assoc. Editor

C D A J O U R N A L , V O L 4 9 , Nº 6

Start at the Beginning Brian Shue, DDS, CDE

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tudents face many ethical dilemmas while in dental school. In a national survey, the ethics educators at each school were asked to list these concerns. Out of the 49 responses received, the most common ethical matter was cheating on written tests (mentioned 25 times), followed by pressure for clinical productivity/ requirements (14), a wide range of differing treatment plans from clinical faculty (eight) and a lack of civility and/or professionalism (eight). Other responses included one-time licensure exams, respect for patients, quality of students, substance abuse and educational debt.1 Today’s promising dental students must have strong ethical values to ensure the success of our profession in the future. It’s clear they know their professional duty. In 2020, the American Dental Education Association (ADEA) asked dental school seniors for their opinion on this statement: “I understand the ethical and professional values that are expected of the profession.” An overwhelming 98% either strongly agreed or agreed (total of 2,427) and only 42 strongly disagreed or disagreed.2 Although that is reassuring, understanding expectations can be quite different than doing the right thing. Dental schools are required to teach ethics. An ADEA survey of dental students in 2017 found “seniors’ perceptions of time devoted to ethics education” were seen as: appropriate 85.8%, excessive 11.1% and inadequate 2.7% (4,809 responses). The statistics were about the same for 2016 and 2015. So not all students look at

It is necessary to strengthen ethics right from the beginning. And ethics need to be present in the first place. There are students who want to do the right thing. the subject of ethics the same way. Providing a mandatory course to an ethically challenged individual doesn’t necessarily change that person’s actions or even moral character. It is necessary to strengthen ethics right from the beginning. And ethics need to be present in the first place. There are students who want to do the right thing. Those are the students who need to be encouraged to continue to make the right decisions, beyond didactic courses, in their future decision-making. In 2007, several dental students and a dental hygiene student from the Herman Ostrow School of Dentistry at USC had that exact thought. They independently went to their ethics professor, Alvin Rosenblum, DDS, to express their concerns. As a result, the students created a studentcentered organization to develop professionalism, with Dr. Rosenblum acting as an advisor. It did not replace the judicial functions of the school’s existing ethics committee. More than 100 students, faculty and staff attended the club’s first event. They also created a startup kit for other dental students across the country to establish similar clubs. This developed into the nationwide Professionalism and Ethics Association

in Dentistry (SPEA). Its mission is to “promote and support students’ lifelong commitment to ethical behavior in order to benefit the patients they serve and to further the dental profession.” SPEA’s objective is to “act as a support system for students in strengthening their personal and professional ethics values.” It aims to meet its mission by providing resources. It allows for ethics communication and promotes awareness of ethics. It also aims to collaborate with dental leadership. All dental students are invited to join; no membership dues are required. The organization now has 35 active chapters and 568 members across the United States and Canada. SPEA will hold its eleventh annual session this fall. It’s a “weekend of personal development, distinguished guest speakers, professionalism and ethics workshops as well as collaborating and connecting with fellow passionate SPEA members across the country,” according to its website at speadental. org. National SPEA Executive Chair Becca Long (USC class of 2022) said SPEA’s biggest accomplishment this year was a collaboration with the American College of Dentists to create a master list of SPEA chapters, student representatives and ACD mentor contacts for its website.  JUNE 2 0 2 1

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Local activities occur throughout the year too. For example, the chapter at USC just collaborated with the Student National Dental Association during Black History Month to co-host faculty guests who discussed real-life situations with ethical dilemmas. More than 150 participants attended this Zoom event. This chapter also recently held small discussion groups with first-year students. Long said, “We are able to talk with them about why ethics are important and how it can affect your decisions from day one in dental school.” We are encouraged to reach out, collaborate and support the school SPEA chapters. Go to the website and click on “ACD/SPEA Collaboration” to get contact information. You will find active chapters in California at the schools of dentistry of UCLA, UCSF, USC and Pacific Dugoni. Help nurture professionalism in our dental school students. Dr. Rosenblum recommends that we can become volunteer faculty members at our schools of dentistry and be positive influences. It is commendable that SPEA members, who may make up a minority of the total student body of each of their respective dental schools, outwardly express their belief in strong professionalism and ethics. Such individuals make up the future leaders of our profession. Think about the impact they will make. Who would you want to lead our profession at the component level? State level? National level? Strong ethical leadership determines the direction our dental organizations will take. It should be dependent on those who we believe will have the best interests of our profession on their minds and in their actions. As dentists, practicing ethically has a profound impact in the public realm. 366 JUNE

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Just look at the annual Gallup Poll’s question that asks “how would you rate the honesty and ethical standards” of a list of professionals. The results are quite frank. Car salespeople and members of Congress almost always score at the bottom. Conversely, nurses almost always rank at the top with physicians a distant second. Dentists are not always included in the revolving list of job categories, but when they are, you can find us barely in the top five of the health professions. Is that good enough? In the last Gallup Poll to include dentists, which was in 2016, only 59% of those polled ranked the ethics of dentists as “very high” or “high.” Conversely, that means 41% believed our standards are “average” or “low/very low.” That is troubling. We all need to consider strengthening the public’s continued trust in our profession. Support the Student Professionalism and Ethics Association in dentistry. It will foster a great foundation for our dental students and also hold our profession to a higher standard. n RE FE RE N CE S 1. Chambers DW. Survey of Dental Ethics Education: 2018. J Am Coll Dent 2020;87(1):48–55. 2. Istrate EC, et al. Dentists of tomorrow 2020: An analysis of the results of the 2020 ADEA survey of U.S. dental school seniors summary report. ADEA Education Research Series. March 2021.

The Journal welcomes letters We reserve the right to edit all communications. Letters should discuss an item published in the Journal within the last two months or matters of general interest to our readership. Letters must be no more than 500 words and cite no more than five references. No illustrations will be accepted. Letters should be submitted at editorialmanager. com/jcaldentassoc. By sending the letter, the author certifies that neither the letter nor one with substantially similar content under the writer’s authorship has been published or is being considered for publication elsewhere, and the author acknowledges and agrees that the letter and all rights with regard to the letter become the property of CDA.


Impressions

C D A J O U R N A L , V O L 4 9 , Nº 6

A New Drug Target for Treating Toothaches

Odontoblasts containing the ion channel TRPC5 (green) tightly pack the area between the pulp and the dentin in a mouse’s molar. The cells’ long-haired extensions fill the thin canals in dentin that extend toward the enamel. (Bernal L. et al. Licensed under Creative Commons CC BY-NC 4.0.)

An international team of scientists has figured out how teeth sense the cold and has pinpointed the molecular and cellular players involved. The team led by David Clapham, MD, PhD, vice president and chief scientific officer of the Howard Hughes Medical Institute, reported that tooth cells called odontoblasts contain cold-sensitive proteins that detect temperature drops in both mice and humans. Signals from these cells can ultimately trigger a jolt of pain to the brain. The study was published in the journal Science Advances in March. The work offers an explanation for how one age-old home remedy eases toothaches. The main ingredient in clove oil, which has been used for centuries in dentistry, contains a chemical that blocks the “cold sensor” protein, said electrophysiologist Katharina Zimmermann, PhD, who led the work at Friedrich-Alexander University ErlangenNürnberg in Germany. Developing drugs that target this sensor even more specifically could potentially eliminate tooth sensitivity to cold, Dr. Zimmermann said. “Once you have a molecule to target, there is a possibility of treatment.” About 15 years ago, the research team discovered that an ion channel called TRPC5 was highly sensitive to the cold. But the team didn’t know where in the body TRPC5’s cold-sensing ability came into play. It wasn’t the skin, they found. Mice that lacked the ion channel could still sense the cold, the team reported in 2011 in the journal Proceedings of the National Academy of Sciences. But TRPC5 does reside in teeth and more so in teeth with caries, as study co-author Jochen Lennerz, MD, PhD, a pathologist from Massachusetts General Hospital, discovered after examining specimens from human adults. A novel experimental set up in mice convinced the researchers that TRPC5 indeed functions as a cold sensor. Instead of cracking a tooth open and solely examining its cells in a dish, Dr. Zimmermann’s team looked at the whole system: jawbone, teeth and tooth nerves. The team recorded neural activity as an ice-cold solution touched the tooth. In normal mice, this frigid dip sparked nerve activity, indicating the tooth was sensing the cold. This was not so in mice lacking TRPC5 or in teeth treated with a chemical that blocked the ion channel. That was a key clue that the ion channel could detect cold. One other ion channel the team studied, TRPA1, also seemed to play a role. The team traced TRPC5’s location to a specific cell type, the odontoblast, that resides between the pulp and the dentin. When someone with a dentin-exposed tooth bites down on a frozen pop, for example, those TRPC5-packed cells pick up on the cold sensation and an “ow!” signal speeds to the brain. Read more of this study in Science Advances (2021); dx.doi. org/10.1126/sciadv.abf5567. n  JUNE 2 0 2 1

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Antibody for USAG-1 Stimulates Tooth Growth Study Finds Increased Hypertension in Patients With Periodontitis Adults with periodontitis may be significantly more likely to have higher blood pressure compared to individuals who have healthy gums, according to new research published in the journal Hypertension. Researchers at the UCL Eastman Dental Institute in London investigated the association between severe periodontitis and high blood pressure in healthy adults without a confirmed diagnosis of hypertension. The study included 250 adults with generalized, severe periodontitis and a control group of 250 adults who did not have periodontitis, all of whom were otherwise healthy and had no other chronic health conditions. The median age of the participants was 35 years and 52.6% were female. All participants underwent comprehensive periodontal examinations including detailed measures of gum disease severity, such as full-mouth dental plaque, bleeding of the gums and the depth of infected gum pockets. Blood pressure assessments were measured three times for each participant to ensure accuracy. Fasting blood samples were also collected and analyzed for high levels of white blood cells and high sensitivity C-reactive protein (hsCRP), as both are markers of increased inflammation in the body. Additional information analyzed as confounders included family history of cardiovascular disease, age, body mass index, gender, ethnicity, smoking and physical activity levels. 368 JUNE

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A new study by scientists at Kyoto University and the University of Fukui reports that an antibody for one gene — uterine sensitization associated gene-1 or USAG-1 — can stimulate tooth growth in mice suffering from tooth agenesis, a congenital condition. The paper was published in Science Advances. The scientists investigated the effects of several monoclonal antibodies for USAG-1. Monoclonal antibodies are commonly used to treat cancers, arthritis and in vaccine development. USAG-1 interacts with both BMP and Wnt. As a result, several of the antibodies led to poor birth and survival rates of the mice, affirming the importance of both BMP and Wnt on whole body growth. One promising antibody, however, disrupted the interaction of USAG-1 with BMP only, according to the study. Experiments with this antibody revealed that BMP signaling is essential for determining the number of teeth in mice. Moreover, a single administration was enough to generate a whole tooth. Subsequent experiments showed the same benefits in ferrets. The study is the first to show the benefits of monoclonal antibodies on tooth regeneration and provides a new therapeutic framework for a clinical problem that can currently only be resolved with implants and other artificial measures. “Conventional tissue engineering is not suitable for tooth regeneration. Our study shows that cell-free molecular therapy is effective for a wide range of congenital tooth agenesis,” said study author Manabu Sugai, PhD, of the University of Fukui. Read more of this study in Science Advances (2021); dx.doi.org/10.1126/sciadv.abf1798. Frontal hematoxylin and eosin–stained sections of the left maxillary incisor and third molar in mice immediately after birth. (MurashimaSuginami et al. Licensed under Creative Commons CC BY-NC 4.0.)

The researchers found that a diagnosis of periodontitis was associated with higher odds of hypertension, independent of common cardiovascular risk factors. Individuals with gum disease were twice as likely to have high systolic blood pressure values compared to people with healthy gums (14% and 7%, respectively). Researchers also found the presence of active gum inflammation (identified by bleeding gums) was associated with higher systolic blood pressure.

Participants with periodontitis also exhibited increased glucose, LDL (“bad” cholesterol), hsCRP and white blood cell levels, and lower HDL (“good” cholesterol) levels compared to those in the control group. Additionally, nearly 50% of participants with gum disease and 42% of the control group had blood pressure values for a diagnosis of hypertension. Learn more about this study in Hypertension (2021); dx.doi.org/10.1161/ HYPERTENSIONAHA.120.16790.


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Consensus Brings Awareness to Underrecognized Condition Henry Ford physician John Craig, MD, is leading an international research effort to improve the multidisciplinary collaboration between otolaryngologists and dental providers around the globe when it comes to diagnosing odontogenic sinusitis (ODS). Dr. Craig, an ear, nose and throat (ENT) surgeon who specializes in rhinology, the care and treatment of the sinuses and nasal cavities, recently led an international consensus statement

for diagnosing ODS in conjunction with Alberto Saibene, MD, MA, from the University of Milan in Italy and 15 other authors from around the world. The consensus statement was published in the International Forum of Allergy and Rhinology. The study’s 17 authors included otolaryngologists and dental specialists from the U.S., Italy, Germany, Lithuania, France, Israel, Japan and

Study Supports Effectiveness of School-Based Stress-Related Dental ProgramDental Conditions Continue To Increase

More than 70% of dentists surveyed by the American Dental Association (ADA) A longitudinal study published in the Journal of the American Dental Association Health Policy Institute are seeing an increase of patients experiencing teeth grinding found that over six years, the percentage of children with untreated caries in the and clenching, conditions often associated with stress. This is an increase from ADA ForsythKids preventive dentistry program decreased from 39% to 19%, suggesting that data released in the fall that showed just under 60% of dentists had seen an increase school-based prevention programs are effective in combating childhood dental disease. among their patients. The ForsythKids mobile dental program has provided no-cost preventive oral health “Our polling has served as a barometer for pandemic stress affecting patients and care to children and teens at schools, community centers and other sites across communities seen through the eyes of dentists,” said Marko Vujicic, PhD, chief Massachusetts since 2003. economist and vice president of the ADA Health Policy Institute. “The increase over Researchers analyzed untreated decay in a cohort of nearly 7,000 children enrolled time suggests stress-related conditions have become substantially more prevalent since in the program from 33 public elementary schools in Massachusetts, all of which are the onset of COVID-19.” classified as Title I, with high numbers of children from low-income families. School-based The survey also found a little more than 60% of dentists saw an increase in other dental treatment helps families overcome common barriers to accessing care, said Helen stress-related dental conditions including chipped and cracked teeth and Nguyen, MPH, DDS, the public health dentist for the ForsythKids program. temporomandibular joint disorder (TMD) symptoms such as headaches and jaw pain. “Parents are often working a day job, a night job, another job in between,” Dr. Despite speculation from recent news reports that frequent mask wearing may Nguyen said. “If they take time off work to bring their child to the dentist, they could lose impact dental health and cause “mask mouth,” the survey found no meaningful change money or lose their job.” in the prevalence reported for conditions such as bad breath and dry mouth compared She also said many parents are under the impression that a dental visit is costto pre-pandemic. prohibitive or that their child would need to miss a full day of school to visit a dental “As the pandemic continues, dentists are seeing stress-related dental conditions office, even though many of the schools are within a few blocks of a community health more and more,” said Marcelo Araujo, DDS, MS, PhD, ADA chief science officer. “It’s center that offers pediatric dental care. more important than ever for people to maintain their dental health, including seeing “For about half of these kids, we’re the dentist regularly to address any issues that could have long-term impact.” their only source of preventive dental care,” Learn more about the work of the ADA Health Policy Institute. Dr. Nguyen said. Read more in the Journal of the American Dental Association (2021); doi.org/10.1016/j.adaj.2020.12.005. (Credit: Forsyth Institute)

Turkey. Authors were specifically selected for their expertise on ODS. “What makes this medical consensus innovative and different is the international collaboration between rhinologists (sinus surgeons) and dental specialists (endodontists and oral surgeons) to achieve consensus on diagnosing ODS,” said Dr. Craig. “The multidisciplinary nature was critical to highlight the importance of collaboration between ENT and dental providers to diagnose this condition.” Dr. Craig has researched ODS for the past five years and has published nearly a dozen studies on various aspects of ODS in the last two years. Now, he is spearheading an international effort to help inform the medical and dental communities. He hopes the published international consensus statement will bring more peer attention to ODS globally, and that ODS diagnosis, as well as its management, can be included more thoroughly in future iterations of national and international sinusitis guidelines. Dr. Craig also hopes this information can be disseminated to all dental specialties through their respective guidelines as well. Improving awareness among otolaryngologists and dental specialists will hopefully improve collaboration between the two fields to diagnose ODS. Dr. Craig’s overriding message to clinicians is: “If you don’t look for ODS, you’ll often miss it. If you start looking for it, you’ll be amazed how many patients you help.” Learn more about the international consensus statement at henryford.com/ news/2021/03/diagnosingodontogenic-sinusitis.  JUNE 2 0 2 1

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introduction C D A J O U R N A L , V O L 4 9 , Nº 6

Merging Well-Founded Principles With New Trends in Prosthodontics Evangelos Rossopoulos, DDS

“The measure of a man is what he does with power.” — Plato GUEST EDITOR Evangelos Rossopoulos, DDS, has been practicing prosthodontics in Whittier, Corona and Huntington Beach California since 1987 and he holds faculty positions at UCLA and the Eastman Institute of Oral Health in Rochester, N.Y. He is the president of the American Prosthodontic Society and is a member of the CDA Presents Board of Managers and a prosthodontist lead at CDA Cares. Conflict of Interest Disclosure: None reported.

T

he term “measure of a man” refers to the character of a person. The character and integrity of a person can be measured by the way they respond to the power they are given. This is true for many aspects of dentistry but especially in the field of prosthodontics. Pierre Fauchard, the father of modern dentistry, replaced missing teeth by carving ivory or bone. Dentists have been introduced to the “power” of many technological advances that greatly shaped the way they serve their patients. As dental professionals, we should always be careful when using these powers to better serve our patients. This issue features four prosthodontic articles written at four great institutions with the collaboration of dental educators and students. It was important to involve students and residents, as they are the future of our beloved profession. We could devote thousands of issues to the field of prosthodontics, but these articles give us an introduction on how we are able to merge the important “old-time” prosthodontic principles with

newer technologies that are used to assist the practitioner and teacher alike. “One thing I’ve learned after 21 years – you never know what is gonna come through that door.” That is the introduction from Pawn Stars, a popular television show. As we are serving the prosthodontic patient, we can relate to that quote, as it perfectly applies to our professional careers. No prosthodontic patient is alike and they all present with various personalities, different conditions and a wide range of expectations. The unique needs of each of our patients can only be addressed with proper prosthodontic planning and execution. Dr. Konstantinos Chochlidakis and his team of students and other specialists from the Eastman Institute for Oral Health in Rochester, N.Y., address the unique needs of an ectodermal dysplasia patient and gives us an example on how an interdisciplinary and methodical approach can achieve their oral rehabilitation. In general, the proper prosthodontic treatment for patients with special conditions or diseases, despite  JUNE 2 0 2 1

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their unique challenges, can have an amazing effect on the quality of life, as it improves not only their oral health, but also their psychological growth. Are digital dentures ready for prime time? Digital dentures or computerengineered complete dentures are increasingly becoming popular and replacing traditionally used protocols in the treatment of our edentulous patients. The CAD/CAM revolution has provided dentists with tools that greatly simplify and improve their prostheses fabrication. However, the speed by which new technologies are introduced has left the practitioners wondering whether they should incorporate it in their practices. There is a fine line between adhering to evidence-based dentistry and striving to position one’s practice at the forefront that is greatly affected by the associated marketing. In our second article, Dr. Sarah Bukhari along with her peers and students from the Loma Linda University School of Dentistry provide us with an up-todate evidence consensus statement in the

field of digital dentures in order to assist dentists in their decision to incorporate this technology in their practices. The Dalai Lama once said, “Open your arms to change but don’t let go of your values.” Dr. Steven Sadowsky from the University of the Pacific, Arthur A. Dugoni School of Dentistry, refers to the fact that denture aesthetics might be compromised when only CAD/CAM technology is used in the virtual teeth setup. Merging with this technology the ability to incorporate an analogue try-in of the denture teeth and the ability to change the individual teeth arrangement can greatly enhance the final result. His article also provides a great overview of denture aesthetics, a very important topic that is greatly underreported in the prosthodontic literature. Referring to the value of student involvement in their education, Benjamin Franklin once said, “Tell me and I forget. Teach me and I remember. Involve me and I learn.” To enhance our dental students’ initial involvement,

a simulated oral environment is necessary before they are ready to treat patients. For many years, typodonts and mannequins have been used to introduce the student to a simulated dental environment. Dr. Kumar C. Shah and two UCLA residents introduce us to the concept of “haptic“ technologies and describe how it is currently being piloted to enhance students’ preclinical dental skills development. With this issue, we try to relate the challenges that we all face in treating the prosthodontic patient and the individuality that each presents. There is rapid advancement in all aspects of prosthodontics not only related to clinical applications, such as treating the very challenging patient, but also in following research and enhancing teaching methods. Embracing the rapidly developing new technologies is exciting and beneficial; however, following proven principles and adhering to evidence-based practice is essential to better serving our patients. n

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ectodermal dysplasia C D A J O U R N A L , V O L 4 9 , Nº 6

C.E. Credit

Interdisciplinary Approach for the Oral Rehabilitation of an Ectodermal Dysplasia Patient Konstantinos Chochlidakis, DDS, MS; Evangelia Lampraki, DDS; Maria Gabriela Carranza, DDS; Carlo Ercoli, DDS, MBA; Theocharis Nikellis, DMD; and Alexandra Tsigarida, DDS, MS

abstract Background: Ectodermal dysplasia is a rare genetic disorder with common oral and extraoral manifestations that require a medical-dental multidisciplinary approach. Case description: Dental treatment is often complex, includes treatment in both jaws, starts in early childhood and involves the coordination of multiple treatment phases and specialists. The surgical and prosthetic rehabilitation of an individual with ectodermal dysplasia is presented. Practical implications: Diagnostic and patient communication approaches, key treatment steps and prognostic indicators are emphasized in order to provide a clinically relevant protocol to the reader. Key words: Ectodermal dysplasia, rehabilitation, implants, restorations

AUTHORS Konstantinos Chochlidakis, DDS, MS, is an associate professor and program director in the department of prosthodontics at the Eastman Institute for Oral Health at the University of Rochester, N.Y. He is a fellow of the American College of Prosthodontists. Conflict of Interest Disclosure: None reported. Evangelia Lampraki, DDS, is a prosthodontist in private practice in Dubai, United Arab Emirates. She is a fellow of the American College of Prosthodontists. Conflict of Interest Disclosure: None reported.

Maria Gabriela Carranza, DDS, is an assistant professor at the Eastman Institute for Oral Health at the University of Rochester, N.Y. She is a fellow of the American College of Prosthodontists. Conflict of Interest Disclosure: None reported. Carlo Ercoli, DDS, MBA, is a professor of prosthodontics and periodontics and the chair of the department of prosthodontics at the Eastman Institute for Oral Health at the University of Rochester, N.Y. Conflict of Interest Disclosure: None reported.

Theocharis Nikellis, DMD, is a resident in the department of prosthodontics at the Eastman Institute for Oral Health at the University of Rochester, N.Y. Conflict of Interest Disclosure: None reported.

Alexandra Tsigarida, DDS, MS, is an associate professor and program director in the department of periodontics at the Eastman Institute for Oral Health at the University of Rochester, N.Y. Conflict of Interest Disclosure: None reported.

E

ctodermal dysplasia (ED) is a rare genetic disorder that affects the development and/ or homeostasis of two or more structures of ectodermal origin.1 Reported prevalence is contradictory but is estimated to be 1 in 5,000–100,000 births.1–3 Patients often present with a combination of clinical signs, such as nail malformations, hypotrichosis, sweat gland abnormalities, skin dryness and fragility and dentofacial malformations.1–5 The oral manifestations include dental abnormalities, such as anodontia, hypodontia or oligodontia and, especially in males, underdevelopment of the alveolar processes and tooth shape anomalies.2,3 The latter are often evident with conical or tapered shapes  JUNE 2 0 2 1

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FIGURE 1. Preoperative smile photo.

FIGURE 2 . Preoperative intraoral photo in maximum

intercuspation.

during the diagnostic and planning phase can improve the surgical and prosthetic dental workflows and decrease the duration of the treatment.18 The purpose of this report is to describe the multidisciplinary dental treatment approach of an adult patient diagnosed with ED.

Case Report

FIGURE 3 . Preoperative occlusal maxillary photo.

FIGURE 4 . Preoperative occlusal mandibular photo.

of the maxillary and mandibular incisors and abnormal root formation of the molar teeth.6 Moreover, maxillary hypoplasia, mandibular protrusion, short facial appearance and salivary flow reduction have often been reported.2,3,7 Orofacial impairment in ED patients affects mastication, swallowing, speech and socialization.8 The oral healthrelated quality of life of affected individuals is low and psychological complications are common.9–11 Due to the partial or complete edentulism, underdevelopment of the alveolar ridges is often present with resultant loss of vertical dimension. Due to the complex nature and multilevel manifestations of ED, consideration related to dental treatment should start in early childhood and include a multidisciplinary medicaldental team. Often, speech therapists and psychologists are necessary for the accomplishment of treatment goals.12,13 Depending on the severity and complexities of the patient’s dentofacial conditions, patient expectations and their physical and psychological growth, prosthetic treatment options range from removable dentures to implant-supported removable or fixed prostheses.2,3,7,8,14,15

While dental implants are not ideally placed before the skeletal growth has been completed,16 in ED patients with severe oligodontia or anodontia, the early placement of dental implants, especially in the anterior mandible, has been reported and shown to significantly improve the retention and stability of removable dentures.16 Thus, the strategic use of dental implants for young, growing ED patients appears to be supported in the literature. From a prognostic standpoint, high implant and prosthesis survival rates have been reported in patients with ED, including zygomatic implants.2,14,17 Given the complexities of the treatment for ED patients, the collaboration of multiple specialists, the extended treatment time, the need to ensure adequate and effective communications among the involved clinicians and the patients and their families, it is important that the restorative dentist/prosthodontist be involved early in the care of an ED patient to coordinate the necessary steps with other clinicians to ensure a successful treatment outcome. For this purpose, the judicious utilization of digital technology

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A 32-year-old male patient presented at the University of Rochester Dental Faculty Group for comprehensive evaluation. The patient had been diagnosed with ectodermal dysplasia and was interested in improving his oral function and appearance (FIGURES 1Aand 2 ). Intraoral clinical examination revealed the absence of all permanent teeth except for the maxillary left second molar, left and right first molars, right first premolar and central incisors, mandibular first molars and mandibular lateral incisors (FIGURES 3Aand 4 ). Several retained deciduous teeth were present, specifically the maxillary second molars, canines, lateral incisors and mandibular second molars, first molars and canines. Several teeth presented a conical shape, maxillary and mandibular arches appeared underdeveloped and the patient was diagnosed with severe malocclusion and loss of vertical dimension. Mandibular bilateral tori were observed. A cone beam computed tomography (CBCT) (i-CAT FLX, KaVo Kerr, Brea, Calif.) was taken and confirmed the intraoral findings (FIGURE 5 ). CBCT findings included vertical bone height of 5 mm in the sinus areas, and grafting would be required before any implant placement. Initial alginate impressions were taken (Jeltrate, Dentsply Sirona, Charlotte, N.C.) and diagnostic casts fabricated. Centric relation was recorded in order to mount the diagnostic casts. Extraoral landmarks were used to fabricate a


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wax-up at an increased by 2 mm vertical dimension of occlusion (VDO). A composite resin mock-up was then made and tried in the patient’s mouth to evaluate aesthetics and phonetics at the new proposed VDO and to obtain the patient’s acceptance (FIGURE 6 ). An orthodontic consultation was sought and concluded that, for this patient, an adequate treatment outcome could be achieved without orthodontic treatment by the time the patient was satisfied aesthetically by the diagnostic mock-up. The treatment plan included extraction of all deciduous teeth, bone augmentation procedures in four quadrants and the placement of 11 dental implants. The prosthetic treatment included all-ceramic, complete-coverage crowns and a fixed partial denture on the residual permanent teeth. Fixed implantsupported ceramic restorations were also planned for the implants placed in the edentulous sites. Stereolithographic (STL) files of the mock-up were imported into a digital design software (Exocad, Darmstadt, Germany) (FIGURE 7); polymethylmethacrylate (PMMA) (Telio-CAD, Ivoclar Vivadent, Buffalo, N.Y.) full-arch provisional fixed partial dentures (FPDs) were then milled with a 5-axis mill (Roland DWX-51D, Roland DGA Corp., Irvine, Calif.) powered by a dedicated manufacturing software (Millbox, CIMsystem, Cinisello Balsamo, Italy). At the initial treatment appointment, tooth preparation of the maxillary and mandibular permanent teeth chosen as abutments was completed, deciduous teeth were extracted and surgical crown lengthening on the maxillary right first premolar was performed. The provisional PMMA prostheses were relined intraorally with self-polymerizing acrylic resin, finished, polished and delivered with a eugenol-based luting agent (FIGURE 8 ).

FIGURE 5 . Preoperative panoramic radiograph.

FIGURE 6 . Intraoral mock-up for anterior maxillary

canine to canine.

FIGURE 7. Digital design of the full-arch milled provisional restorations.

FIGURE 8 . Relined full-arch milled provisional

restorations.

FIGURE 9. Milled provisional restorations used as surgical templates.

FIGURE 10 . Implant placement in the mandible.

After two months of healing, bone augmentation procedures were carried out. Maxillary sinus augmentations were performed bilaterally via an indirect and direct approach on the right and left side, respectively, with a combination of xenograft (Bio-Oss, Geistlich Pharma North America, Princeton, N.J.) and allograft (Straumann Allograft, Straumann USA LLC, Andover, Mass.) materials. Three months later, a new set of the provisional FPDs were milled, modified to serve as a surgical template (FIGURE 9 ) and used to guide the placement of 11 implants in the maxillary and mandibular arches (BLT, Straumann USA LLC) (FIGURE 10 ).

Three months post-implant placement, uncovering surgeries were performed and healing abutments placed. At the same visit, open tray implant impressions were taken with polyether material (Permadyne, 3M, St Paul, Minn.) and jaw relation records taken for the fabrication of a new set of implant-supported and teeth-supported fixed provisional restorations. These prostheses guided soft tissue contouring for the implant and pontic sites for two months and allowed the patient a final assessment of the aesthetics, phonetics and function ahead of the definitive prosthesis fabrication (FIGURE 11 ). Final maxillary and mandibular open tray implant impressions were again made  JUNE 2 0 2 1

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FIGURE 11. Milled provisional restorations for soft

FIGURE 12 . Definitive maxillary restorations on cast.

tissue contouring.

FIGURE 14A . Definitive frontal restorations at one-

FIGURE 14B . Postoperative smile photo at one-year

year follow-up.

follow-up.

with polyether material (Permadyne, 3M). The definitive tooth-supported prostheses consisted of monolithic, zirconia (KATANA Noritake Zirconia STML, Kuraray America Inc., New York) single crowns for the four molars; feldspathic porcelain-veneered, zirconia (KATANA Noritake Zirconia STML, Kuraray America Inc.) bilayered restorations were chosen for the single crowns on the maxillary central incisors, first premolar and the fixed partial denture in the anterior mandible. For the implantsupported prostheses, a monolithic design was used for the screw-retained single implant-supported crown on the maxillary right second premolar while monolithic, screw-retained, splinted, fixed partial dentures were fabricated in the second, third and fourth quadrants (FIGURES 12 and 13 ). Screw retention was designed for all implant-supported prostheses with the utilization of screw channel, angled abutments (Variobase AS, Straumann USA LLC) to facilitate laboratory design and optimize the location of the screw channel. A maxillary PMMA occlusal orthotic was then fabricated. The patient

was again instructed and motivated on self-performed plaque removal measures and enrolled in a six-month maintenance program. Patient was very satisfied with the final outcome and was compliant with oral hygiene at the follow-up maintenance appointments (FIGURES 14 and 15 ).

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FIGURE 13 . Definitive mandibular restorations

on cast.

Discussion

Ectodermal dysplasia is a rare congenital disease that affects several ectodermal structures. Manifestations of the disease differ in severity and can involve teeth, skin, hair, nails and sweat glands.19 Intraoral examination in an ED patient usually reveals hypodontia and oligodontia usually with peg-shaped teeth. Dental and alveolar process hypodevelopments with resultant malocclusion often compromise lip support and are responsible for a decreased lower facial height. A multidisciplinary team effort involving oral and maxillofacial, orthodontic, periodontic and prosthodontic specialists is often required for the treatment of the dentofacial deformities presented by ED patients.20 In this case

FIGURE 15 . Postoperative panoramic radiograph at one-year follow-up.

report, though, orthodontic treatment was not included because the diagnostic mock-up showed that the position of the permanent teeth and the alveolar arch relationships could provide for an adequate projected prosthetic outcome. While the treatment of ED patients is often complex and lasts several years, the restoration of adequate occlusion not only improves chewing function but also enhances the patient’s self-confidence and quality of life.3 For children, removable dentures are generally considered an appropriate treatment option especially during growth, but fixed, implant-supported prostheses are often a treatment of choice for adults.20,21 A challenge related to the placement of dental implants may be constituted by the hypodevelopment of the alveolar processes in ED patients and the resultant need for bone grafting. While ridge augmentation grafting was successfully executed for this patient, the maintenance of the deciduous teeth had likely decreased the residual ridge resorption that could have otherwise


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been anticipated. It is therefore important during the early phases of treatment to retain healthy deciduous teeth until ridge augmentation and implant placement can be carried out. Once implants are placed, the implants may provide stimulation to maintain alveolar ridge dimensions.22 An international Delphi study designed to establish clinical guidelines and consensus for the treatment approach in children with ectodermal dysplasia included the use of dental implants.20 Even though moderately high implant failures (range of 9% to 24%) have been described in ED patients, there has been agreement that implant placement is an indicated treatment modality, even in the mandibular canine region, in 5- to10-year-old patients.20,23–26 However, implant placement should be avoided adjacent to teeth until the completion of facial growth.20 For the patient presented in this article, these considerations were moot, as the patient presented after the completion of his growth. Regarding the design of the prosthetic restorations, a single implant was used on the maxillary right canine for a cantilever fixed partial denture on the maxillary lateral incisor. Due to the very resorbed ridge in the lateral incisor site and the challenges that a vertical augmentation could hinder, the cantilever option was chosen. A systematic review by Pjetursson et al.27 has shown high implant and prosthesis survival for the cantilever FPDs after 10 years of followup. The survival rate of cantilever FPDs was 5% less than conventional implant FPDs, but this solution was something that was more predictable than placing narrow and short diameter implants due to bone width and distally inclined roots of the central incisors. The implant FPDs that were used in the second, third and fourth quadrant were splinted instead of individual

implant crowns. The patient was informed about the option of having individual implant crowns as compared to FPDs, and he chose to have the latter. The advantages that splinted crowns may offer are the easier fabrication process, decreased chairtime during the delivery of the prosthesis and better stress distribution in the implant/ abutment and cortical bone tissue.28,29 On the contrary, patients with splinted crowns are not able to floss in between the crowns, which may make oral hygiene more difficult in these areas. A

Once implants are placed, the implants may provide stimulation to maintain alveolar ridge dimensions.

recent study by Yi et al.30 showed that an implant splinted to both mesial and distal adjacent implant has a higher risk for peri-implantitis. Our patient had excellent oral hygiene throughout the treatment and was a good candidate for splinted implant crowns. The restorative material chosen for the definitive restorations was zirconia. Due to the short clinical crowns and existing previous direct restorations on the remaining permanent molars and premolar, complete coverage instead of partial coverage crowns was the design of choice. Several studies have reported survival outcomes and biocompatibility for both teeth as well as implant zirconia restorations.31–35 More specifically, monolithic zirconia crowns on teeth and implants with a five-year follow-up

period have shown approximately 95% and 97% survival rates, respectively.31,32 Even though the material of choice has a high survival rate, any patients with tooth- and implant-supported prostheses will need a high mechanical and biological maintenance and recall protocol for a successful clinical result.36

Conclusions

The diagnosis of ED is of the utmost importance for the early development of a comprehensive, interdisciplinary treatment plan. While dental and maxillofacial treatment of ED patients often takes several years, it is of paramount importance to design a team-based treatment approach that visualizes the planned outcome and is communicated to the patient and family early during the initial patient evaluation. Once treatment goals are identified and agreed upon, the rehabilitation of the ED patient can proceed toward an improvement of the aesthetics, phonetics and function and hopefully aid in increasing patient self-esteem and overall quality of life. n RE F E RE N C E S 1. Wright JT, Fete M, Schneider H, Zinser M, Koster MI, Clarke AJ, et al. Ectodermal dysplasias: Classification and organization by phenotype, genotype and molecular pathway. Am J Med Genet A 2019 Mar;179(3):442–447. doi: 10.1002/ajmg.a.61045. Epub 2019 Jan 31. 2. Chrcanovic BR. Dental implants in patients with ectodermal dysplasia: A systematic review. J Craniomaxillofac Surg 2018 Aug;46(8):1211–1217. doi: 10.1016/j.jcms.2018.05.038. Epub 2018 May 21. 3. Wang Y, He J, Decker AM, Hu JC, Zou D. Clinical outcomes of implant therapy in ectodermal dysplasia patients: A systematic review. Int J Oral Maxillofac Surg 2016 Aug;45(8):1035–43. doi: 10.1016/j.ijom.2016.03.011. Epub 2016 Apr 2. 4. Adhe V, Dongre A, Khopkar U. Ectodermal dysplasia-skin fragility syndrome. Indian J Dermatol Venereol Leprol Jul–Aug 2011;77(4):503–6. doi: 10.4103/0378-6323.82415. 5. Chokshi A, Chokshi K, Chokshi R, Mhambrey S. Ectodermal dysplasia: A review. Int J Oral Health Med Res 2015;2: 101–4. 6. Lexner MO, Bardow A, Hertz JM, Nielsen LA, Kreiborg S. Anomalies of tooth formation in hypohidrotic ectodermal dysplasia. Int J Paediatr Dent 2007 Jan;17(1):10–8. doi: 10.1111/j.1365-263X.2006.00801.x.  JUNE 2 0 2 1

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7. Hickey AJ, Vergo TJ Jr. Prosthetic treatments for patients with ectodermal dysplasia. J Prosthet Dent 2001 Oct;86(4):364– 8. doi: 10.1067/mpr.2001.118876. 8. Schnabl D, Gerhard S, Biedermann R, Crismani A, Rasse M, Zauza K, et al. Dental management and prosthetic rehabilitation of patients suffering from hypohidrotic ectodermal dysplasia: A report of two case histories. Int J Prosthodont Nov/Dec 2018;31(6):552–557. doi: 10.11607/ijp.5857. Epub 2018 Sep 6. 9. Saltnes SS, Jensen JL, Sæves R, Nordgarden H, Geirdal AØ. Associations between ectodermal dysplasia, psychological distress and quality of life in a group of adults with oligodontia. Acta Odontol Scand 2017 Nov;75(8):564–572. doi: 10.1080/00016357.2017.1357189. Epub 2017 Jul 28. 10. Machado M, Wallace C, Austin B, Deshpande S, Lai A, Whittle T, et al. Rehabilitation of ectodermal dysplasia patients presenting with hypodontia: Outcomes of implant rehabilitation part 1. J Prosthodont Res 2018 Oct;62(4):473–478. doi: 10.1016/j.jpor.2018.07.001. Epub 2018 Jul 24. 11. Hanisch M, Sielker S, Jung S, Kleinheinz J, Bohner L. Self-assessment of oral health-related quality of life in people with ectodermal dysplasia in Germany. Int J Environ Res Public Health 2019 May 31;16(11):1933. doi: 10.3390/ ijerph16111933. 12. Hobkirk JA, Nohl F, Bergendal B, Storhaug K, Richter MK. The management of ectodermal dysplasia and severe hypodontia. International conference statements. J Oral Rehabil 2006 Sep;33(9):634–7. doi: 10.1111/j.13652842.2006.01628.x. 13. Bergendal B, Bjerklin K, Bergendal T, Koch G. Dental implant therapy for a child with X-linked hypohidrotic ectodermal dysplasia — three decades of managed care. Int J Prosthodont Jul–Aug 2015;28(4):348–56. doi: 10.11607/ ijp.4242. 14. Crawford PJ, Aldred MJ, Clarke A, Tso MS. Rapp-Hodgkin syndrome: An ectodermal dysplasia involving the teeth, hair, nails and palate. Report of a case and review of the literature. Oral Surg Oral Med Oral Pathol 1989 Jan;67(1):50–62. doi: 10.1016/0030-4220(89)90302-2. 15. Ramos V, Giebink DL, Fisher JG, Christensen LC. Complete dentures for a child with hypohidrotic ectodermal dysplasia: A clinical report. J Prosthet Dent 1995 Oct;74(4):329–31. doi: 10.1016/s0022-3913(05)80369-5. 16. Cronin RJ Jr., Oesterle LJ. Implant use in growing patients. Treatment planning concerns. Dent Clin North Am 1998 Jan;42(1):1–34. 17. Goker F, Grecchi E, Mancini EG, Del Fabbro M, Grecchi F. Zygomatic implant survival in 9 ectodermal dysplasia patients with 3.5- to 7-year follow-up. Oral Dis 2020 Nov;26(8):1803–1809. doi: 10.1111/odi.13505. Epub 2020 Jul 13. 18. Nguyen JP, Chandy TS, Sparks J, Driscoll CF, Masri R. Leveraging digital technology for treatment of young patients with congenital conditions: A clinical report. J Prosthodont Aug 2020. doi.org/10.1111/jopr.13241. 19. Itin PH. Etiology and pathogenesis of ectodermal dysplasias. Am J Med Genet A 2014 Oct;164A(10):2472–7. doi: 10.1002/ajmg.a.36550. Epub 2014 Apr 8. 20. Klineberg I, Cameron A, Whittle T, Hobkirk J, Bergendal B, Maniere MC, et al. Rehabilitation of children with ectodermal dysplasia. Part 1: An international Delphi study. Int J Oral Maxillofac Implants Jul–Aug 2013;28(4):1090–100. doi: 10.11607/jomi.2980.

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21. Nowak AJ. Dental treatment for patients with ectodermal dysplasias. Birth Defects Orig Artic Ser 1988;24(2):243–52. 22. Escobar V, Epker BN. Alveolar bone growth in response to endosteal implants in two patients with ectodermal dysplasia. Int J Oral Maxillofac Surg 1998 Dec;27(6):445–7. doi: 10.1016/s0901-5027(98)80034-9. 23. Bergendal B. Interpretive and report bias in publications on implants in patients with ectodermal dysplasia. Int J Prosthodont Nov–Dec 2011;24(6):505–6. 24. Kearns G, Sharma A, Perrott D, Schmidt B, Kaban L, Vargervik K. Placement of endosseous implants in children and adolescents with hereditary ectodermal dysplasia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999 Jul;88(1):5– 10. doi: 10.1016/s1079-2104(99)70185-x. 25. Guckes AD, Scurria MS, King TS, McCarthy GR, Brahim JS. Prospective clinical trial of dental implants in persons with ectodermal dysplasia. J Prosthet Dent 2002 Jul;88(1):21–5. 26. Sweeney IP, Ferguson JW, Heggie AA, Lucas JO. Treatment outcomes for adolescent ectodermal dysplasia patients treated with dental implants. Int J Paediatr Dent 2005 Jul;15(4):241– 8. doi: 10.1111/j.1365-263X.2005.00610.x. 27. Pjetursson BE, Brägger U, Lang NP, Zwahlen M. Comparison of survival and complication rates of toothsupported fixed dental prostheses (FDPs) and implantsupported FDPs and single crowns (SCs). Clin Oral Implants Res 2007 Jun;18 Suppl 3:97–113. doi: 10.1111/j.16000501.2007.01439.x. 28. Yilmaz B, Mess J, Seidt J, Clelland NL. Strain comparisons for splinted and nonsplinted cement-retained implant crowns. Int J Prosthodont May–Jun 2013;26(3):235–8. doi: 10.11607/ijp.3254. 29. Nissan J, Ghelfan O, Gross M, Chaushu G. Analysis of load transfer and stress distribution by splinted and unsplinted implant-supported fixed cemented restorations. J Oral Rehabil 2010 Sep;37(9):658–62. doi: 10.1111/j.13652842.2010.02096.x. Epub 2010 May 20. 30. Yi Y, Koo KT, Schwarz F, Ben Amara H, Heo SJ. Association of prosthetic features and peri-implantitis: A crosssectional study. J Clin Periodontol 2020 Mar;47(3):392–403. doi: 10.1111/jcpe.13251. Epub 2020 Jan 21. 31. Pjetursson BE, Valente NA, Strasding M, Zwahlen M, Liu S, Sailer I. A systematic review of the survival and complication rates of zirconia-ceramic and metal-ceramic single crowns. Clin Oral Implants Res 2018 Oct;29 Suppl 16:199-214. doi: 10.1111/clr.13306. 32. Sailer I, Makarov NA, Thoma DS, Zwahlen M, Pjetursson BE. All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part I: Single crowns (SCs). Dent Mater 2015 Jun;31(6):603–23. doi: 10.1016/j. dental.2015.02.011. Epub 2015 Apr 2. 33. Jung RE, Zembic A, Pjetursson BE, Zwahlen M, Thoma DS. Systematic review of the survival rate and the incidence of biological, technical and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of five years. Clin Oral Implants Res 2012 Oct;23 Suppl 6:2–21. doi: 10.1111/j.1600-0501.2012.02547.x. 34. Le M, Papia E, Larsson C. The clinical success of tooth- and implant-supported zirconia-based fixed dental prostheses. A systematic review. J Oral Rehabil 2015 Jun;42(6):467–80. doi: 10.1111/joor.12272. Epub 2015 Jan 10. 35. Larsson C, Wennerberg A. The clinical success of zirconiabased crowns: A systematic review. Int J Prosthodont Jan–Feb

2014;27(1):33–43. doi: 10.11607/ijp.3647. 36. Bidra AS, Daubert DM, Garcia LT, Kosinski TF, Nenn CA, Olsen JA, et al. Clinical practice guidelines for recall and maintenance of patients with tooth-borne and implant-borne dental restorations. J Am Dent Assoc 2016;147:67–74. doi. org/10.1016/j.adaj.2015.12.006. T HE CORRE S P ON DIN G AU T HOR , Konstantinos Chochlidakis, DDS, MS, can be reached at kchochlidakis@ urmc.rochester.edu.


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C .E. CREDIT QUESTIONS

June 2021 Continuing Education Worksheet This worksheet provides readers an opportunity to review C.E. questions for the article “Interdisciplinary Approach for the Oral Rehabilitation of an Ectodermal Dysplasia Patient” before taking the C.E. test online. To take the test online, click here. This activity counts as 0.5 of Core C.E. 1. The cause of ectodermal dysplasia is considered to be: a. A virus b. Trauma c. Insufficient nutrition d. Genetic 2. The oral manifestations of ectodermal dysplasia include: a. Anodontia b. Oligodontia c. Hypodontia d. All of the above 3. The reason for often observing loss of vertical dimension in an ectodermal dysplasia patient is: a. Bruxism b. Rampant caries c. Underdevelopment of the alveolar ridges d. None of the above 4. Implant supported fixed and removable prostheses are not indicated for the ectodermal dysplasia patients. a. True b. False 5. The use of implants for the treatment of the ectodermal dysplasia patient is indicated: a. Only after the age of 21 b. Only for those who present with complete anodontia c. Only if the patient is financially able d. Even in young, growing patients

7. Dentofacial deformities presented by ectodermal dysplasia patients can better be addressed by: a. An endodontist only b. An orthodontist only c. A plastic surgeon d. A multidisciplinary team 8. During the early treatment of an ectodermal dysplasia patient, it is important to remove the patient’s healthy deciduous teeth. a. True b. False 9. Lateral incisors often are replaced with a single canine implant cantilever prosthesis because: a. Of finances b. It is more predictable than placing narrow and short implants at the lateral position c. It provides better aesthetics d. The survival rate is far superior to a fixed partial denture 10. Excellent oral hygiene and follow-up is essential in the long-term prognosis of implant restorations placed during treatment of the ectodermal dysplasia patient. a. True b. False

6. Manifestations of ectodermal dysplasia can also involve: a. Skin b. Hair c. Nails d. All of the above

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IT’S A VERB.


digital dentures C D A J O U R N A L , V O L 4 9 , Nº 6

Computer-Engineered Complete Dentures: Where Are We Now? A Review Sarah Bukhari, BDS, MS; Abdulaziz A. Alzaid, BDS, MS; Raneem Alduraiby, BDS; Periklis Proussaefs, DDS, MS; and Mathew T. Kattadiyil, BDS, MDS, MS

abstract Background: Computer-engineered complete dentures (CECDs) or digital dentures have become a popular option for treating completely edentulous patients. CECDs are fabricated using additive or subtractive methods of manufacturing after the digitizing and designing process. The advantages and disadvantages of CECDs have been reported in the literature. The purpose of this review article was to evaluate the current status of CECDs by conducting a search of related literature. Types of studies reviewed: An electronic search of the English language literature was conducted using PubMed/MEDLINE database from January 1990 to July 2020. Fifty-six articles were reviewed in-depth and variables related to CECDs studied such as accuracy, adaptation, retention, properties, patient satisfaction, number of post insertion adjustments, surface treatment and denture teeth. Results: CECDs continue to be studied vigorously as evidenced by reports in the scientific literature. Milled CECDs are mostly reported to have superior adaptation, flexural strength, modulus of elasticity, fracture toughness, color stability and require less clinical chairtime for fabrication. Practical implications: Despite numerous advantages associated with CECDs, there is no clear scientific evidence yet that they offer a significant improvement in patient satisfaction and quality of life when compared to conventional CDs. Key words: Computer-engineered complete denture, CECD, milled dentures, printed dentures, digital dentures

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AUTHORS Sarah Bukhari, BDS, MS, is an assistant professor in the advanced specialty education program in prosthodontics at the Loma Linda University School of Dentistry. She is a fellow of the American Board of Prosthodontics. Conflict of Interest Disclosure: None reported. Abdulaziz A. Alzaid, BDS, MS, is a teaching assistant in the prosthetic dental science department in the College of Dentistry at King Saud Bin Abdulaziz University for Health Sciences and King Abdullah International Medical Research Center in Riyadh, Saudi Arabia. He is a fellow of prosthodontics and digital technology at the Loma Linda University School of Dentistry. Conflict of Interest Disclosure: None reported.

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Raneem Alduraiby, BDS, is a graduate student in the advanced specialty education program in prosthodontics at the Loma Linda University School of Dentistry. Conflict of Interest Disclosure: None reported. Periklis Proussaefs, DDS, MS, is an associate professor in the advanced specialty education program in prosthodontics and implant dentistry at the Loma Linda University School of Dentistry. Conflict of Interest Disclosure: None reported. Mathew T. Kattadiyil, BDS, MDS, MS, is a professor and the director of the advanced specialty education program in prosthodontics at the Loma Linda University School of Dentistry. Conflict of Interest Disclosure: None reported.

C

omputer-engineered complete dentures (CECDs) or digital dentures have become a popular option for treating completely edentulous patients. Introduced as a concept in the early 1990s,1 the technology used to fabricate complete dentures using a digital process has expanded significantly in the last 10 years. CECDs are fabricated using additive or subtractive methods of manufacturing after the digitizing and designing process.2 The advantages and disadvantages of CECDs have been reported in the literature. The purpose of this review article is to evaluate the current status of CECDs by conducting a search of related literature. An electronic search of the English language literature was conducted using the PubMed/MEDLINE database. Search terms included were CAD-CAM AND complete dentures, digital AND complete dentures, computer-engineered AND complete denture, milled AND dentures, 3D printed, rapid prototyping AND dentures. The search period was from January 1990 to July 2020. The inclusion criteria for the search were: The article be in English and include the specified search terms in the title or the abstract. Articles that did not include search terms described in the inclusion criteria or repetitive data from another article were excluded. The exclusion criteria for the search were technique articles. Systematic reviews were reviewed to look for missed articles, if any. Articles that did not meet descriptions of CAD/ CAM as defined by the Glossary of Prosthodontic Terms3 and not related to the topic of interest were also excluded. The search strategy included three stages: title search, abstract review and full text article selection and review. In stage one, titles obtained from PubMed/ MEDLINE search terms were analyzed

according to the inclusion criteria. Before excluding an article, any disputes in selection were resolved by discussion among the authors (SB, AA, RA). Disputed articles (those that did not meet unanimous consensus among the authors) were still included in the abstract stage for further review. In stage two, abstracts 1B of all selected titles were reviewed, and selected articles and disputed articles were included for full-text analysis. In stage three, the full text of selected articles was reviewed in detail. Any articles that didn’t meet inclusion criteria were excluded and the final list of articles was reviewed in-depth to satisfy the objectives of the systematic review. The PubMed electronic search resulted in 1,726 titles of which 161 titles were considered for further review of abstracts. This resulted in the elimination of 105 articles. The remaining 56 articles were reviewed in-depth for variables related to CECDs studied such as accuracy, adaptation, retention, properties, patient satisfaction, number of post insertion adjustments, surface treatment and denture teeth. The references of these 56 articles were reviewed to ensure no relevant articles were omitted. This best evidence consensus conclusions are based on the review of the selected articles and the parameters studied related to CECDs. A detailed TA BLE is available at cda.org/BukhariTable.

Accuracy of Fit and Adaptation

In an in vitro study by Lee et al.,4 a surface comparing software was used to study the accuracy of denture bases fabricated by injection molding, milling and 3D printing. Milled and 3D printed denture bases displayed higher accuracy than the denture bases fabricated by injection molding. Reproducibility was higher for the injection molded denture bases.


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In an in vitro study, Yoon et al.5 evaluated the trueness of 3D printed denture bases and compared the tissue surface adaptation of 3D printed denture bases with milled and compression molded denture bases. Milled denture bases performed better than the 3D printed ones for trueness (P < .001). 3D printed denture bases had the lowest value for fit discrepancies followed by milled and injection molded denture bases. Significant differences were not seen with respect to tissue surface adaptation of the denture bases, regardless of the fabrication technique (P > .05). Srinivasan et al6 evaluated the trueness of compression molded, injection molded and milled dentures bases. Milled and injection molded denture bases had significantly lower trueness of the intaglio surface compared to conventional denture bases. The authors reported that the trueness of the intaglio surface of all three techniques remained within the clinically acceptable range. McLaughlin et al.7 in an in vitro study compared the denture base shrinkage fabricated by milling, compression molding and injection molding of denture base resins. Milled and injection molded dentures had significantly better adaptation than compression-molded dentures for shallow palates. Most of this difference in space was in the shallow palate groups, which were noted as more susceptible to shrinkage. Hsu et al.8 evaluated the denture base adaptation of milled, 3D printed and compression molding techniques (n = 10). Silicone thickness between the denture base and edentulous model under a 49-N load was measured at eight sites. Adaptation was evaluated by superimposing the scanning data from denture bases and models. Milled dentures had the highest level of adaptation and the 3D printed dentures bases had

the lowest value for trueness of the intaglio surface of the denture base. Steinmassl et al.9 compared milled dentures provided by four different manufacturers were generated from 10 different master casts. The authors reported superior adaptation with milled denture bases compared to compression molded ones. Yoon et al.10 in a clinical study investigated the tissue surface adaptation of compression molded, milled and 3D printed denture bases for 12 edentulous arches. There was

The authors reported superior adaptation with milled denture bases compared to compression molded ones.

no significant difference in the tissue surface adaptation between milled, 3D printed and compression molded denture bases. These findings are in disagreement with the findings of Steinmassl et al. Goodacre et al.11 compared the adaptation of denture bases fabricated conventionally (compression molding, pour, injection molding) and milled denture bases using a surface matching software. Milled denture bases exhibited superior accuracy and reproducibility compared to the conventional techniques of fabrication. Kalberer et al.12 evaluated the trueness of 3D printed and milled CECDs in an in vitro study. They reported significantly superior trueness for the entire milled CECD intaglio surface including the posterior crest, palatal vault, posterior

palatal seal, tuberosity, anterior ridge, vestibular flange, midpalatal raphe areas and the entire intaglio surface.

Retention

Tasaka et al.13 evaluated the accuracy and retention of 3D printed and compression molded denture bases. 3D printed denture bases exhibited higher retention and more accuracy. Alhelal et al.14 in a clinical study compared the retention of compression molded and milled denture bases in the maxillary arch of 20 edentulous subjects. A custom-designed electronic testing device was used to measure denture retention. Significantly higher retention with milled denture bases was reported. Alrumaih et al.15 using the same methodology evaluated the effectiveness of denture adhesive on the retention of milled and compression molded denture bases. Denture adhesive application interestingly decreased the overall retention of milled denture bases compared to the retention when no adhesive was used. The authors reported that the use of denture adhesive did not significantly improve retention values between the milled and the compression molded bases. The retention of the conventional bases was not significantly increased by using adhesive.

Physical Properties

Aguirre et al.16 performed an in vitro study comparing the flexural strength flexural modulus of milled, injection molded and compression molded denture base material (n = 10 per group). The authors used a three-point bend test with a universal testing machine until failure. The authors reported that milled and compression molded denture base material exhibited more brittle behavior than injection molded denture bases. However, milled denture  JUNE 2 0 2 1

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base material showed higher flexural strength than the other two groups. Steinmassl et al.17 in an in vitro study comparing physical properties of six milled, one injection molded and one autopolymerized denture base materials (n = 10) used a three-point bend test along with electron scanning microscopy (ESM) to evaluate breaking load, fracture toughness, modules of elasticity and fracture surface roughness. The authors found that all milled denture base materials had higher elastic moduli than the conventional materials, but only two of the milled denture base materials had a significantly higher fracture toughness than the conventional materials. The authors reported that milled denture base materials do not generally have a higher fracture tolerance or a higher resistance against crack propagation than conventionally processed denture base materials and that there are large variations in fracture resistance between different milled materials. Furthermore, surface analyses revealed that the resins’ microstructure might be accountable for their mechanical properties, rather than the polymer chain length. Srinivasan et al.18 conducted an in vitro study comparing biocompatibility and mechanical properties of milled and compression molded denture base materials. The authors concluded that milled denture base materials have comparable biocompatibility and presented with more improved mechanical properties than the conventional denture base materials. Ayman19 in an in vitro study evaluated flexural strength and flexural modulus (n = 10), surface hardness (n = 10) and residual monomer content (n = 15) of milled and compression molded denture base materials. The author reported that compression molded denture base material displayed significantly higher 384 JUNE

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flexural strength and lower flexural modulus compared to milled denture base material. Also, milled denture base material had a significantly higher surface hardness and lower monomer release than compression molded denture base material. The author concluded that milled denture base material is a clinically suitable resin with superior physical properties for denture bases. Einarsdottir et al.20 conducted an in vitro study evaluating dimensional stability of milled, injection molded and compression molded denture

Ayman concluded that milled denture base material is a clinically suitable resin with superior physical properties for denture bases.

base materials (n = 15). The authors adapted a double processing method in their protocol. The authors found that the second processing had almost no effect on dimensional stability and most errors were incorporated during the first processing, among which the milled denture base group had significantly less errors. The other two groups had no statistically significant difference in dimensional stability. Prpic ́ et al.21 in an in vitro study indicated that the printed denture base had the least flexural strength while the milled and the polyamide material had the highest. Also, surface hardness was not favorable for the 3D printed material as well as for the polyamide. The authors concluded that milled denture base material, even though not all of them

performed similarly, had better mechanical properties than the other materials and polymerization type cannot be used as an indicator of the material properties. Similarly, Al-Dwairi et al.22 in another in vitro study concluded that milled denture base material showed significant improvement in flexural strength, impact strength and flexural modulus when compared to the conventional material. In their study, there was no significant difference between the two milled denture base materials. However, Perea-Lowery et al.23 performed an in vitro study and found that even though the milled denture base materials showed satisfactory behavior in general, they did not have better mechanical properties than conventional denture base materials. The authors advocated use of conventional material as they showed better results.

Surface Properties

Al-Dwairi et al.24 conducted an in vitro study comparing surface properties of milled and heat polymerized denture base materials. The authors concluded that milled denture base material had significantly higher surface hardness and hydrophobicity in comparison to the compression molded denture base material, while the compression molded denture base material showed the highest surface roughness. The authors also reported that milled denture base material brands might have variable surface hardness, surface roughness and wettability. Alammari25 performed an in vitro study comparing the effect of mechanical and chemical polishing methods on the surface roughness and wettability of milled, compression molded and self-cured denture base material. The author reported that mechanical polishing, which was found to be the most effective polishing method, produced lower surface roughness


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for milled and compression molded denture base material with a smoother surface compared to chemical polishing. Also, significant decrease of the contact angle was observed in milled denture base material with both polishing techniques compared to the other two groups, which led the author to recommend it for complete denture fabrication, especially for elderly patients with reduced salivary functions. The findings of wettability in this study contradict Al-Dwairi et al.24 findings and highlights the influence of polishing protocol. Al-Fouzan et al.26 in an in vitro study investigated the association between surface roughness and adhesion of Candida albicans to milled and compression molded denture base material (n = 10). The authors found that milled denture base material exhibited less roughness and adhesion of Candida albicans compared to compression molded denture base material. Shinawi27 evaluated the effect of cleaning for a simulated period of three years on milled denture base material surface properties. The author found that milled denture base material exhibited a homogenous surface initially with low surface roughness that significantly increased following cleaning for a simulated three-year period. However, the author concluded that these findings were within the clinically acceptable limits and that milled denture base material exhibit favorable resistance to cleaning abrasive forces. Totua et al.28 described a method for incorporating TiO2 nanoparticles in printable denture base material to utilize its antibacterial and antifungal properties. The authors recommended 0.4% by weight TiO2 nanoparticles to be incorporated to achieve a printable material with the desired biological properties. Steinmassl et al.29 conducted a study investigating the effect of the milling

process on surface characteristics of five milled denture base material and compression molded denture base material which served as the control group. The authors found that most milled denture base materials have smoother and more hydrophilic surfaces than compression molded denture base material. Arslan et al.30 in an in vitro study compared the surface roughness, flexural strength and hydrophobicity of milled denture base materials with heatpolymerized polymethylmethacrylate (PMMA) after thermal cycling. They

Milled dentures immersed in red wine had a significantly higher color difference than injection molded dentures.

reported the milled denture base materials had significantly higher flexural strength among all groups. Surface roughness was comparable among all groups while hydrophobicity was higher for the milled denture base materials.

Color Stability

Al-Qarni et al.31 in an in vitro study compared the staining effect on the color stability of milled CECDs with compression molded and injection molded CDs. All specimens were immersed in coffee and red wine and the control group was immersed in distilled water. Color change was measured after seven days with a spectrophotometer. All denture teeth immersed in the staining solutions showed an increase in color difference values. Monolithic milled dentures had

greater resistance to stain accumulation at the tooth-denture base interface than those made with conventional processing methods. Milled dentures immersed in red wine had a significantly higher color difference than injection molded dentures. Monolithic milled dentures had similar color change to conventionally processed acrylic resins.

Denture Teeth

Cha et al.32 in an in vitro study compared the wear of 3D printed and four types of conventionally prefabricated denture teeth against metal and zirconia antagonists. Though they found variable combinations of wear loss among groups with the antagonists used in the study, the overall conclusion was that 3D printed and the prefabricated resin denture teeth had adequate and comparable wear resistance. Choi et al.33 conducted an in vitro study that tested fracture toughness and bonding failure of three types of denture bases with four different types of commercially available denture teeth. Heat polymerized denture base material had the highest fracture toughness and bond strength that significantly decreased with aging. Teeth bonded to milled and 3D printed denture bases had significantly lower bond strength that did not change significantly with aging. Milled denture bases bonded with modified PMMA with nano filler denture teeth had the highest and statistically significant fracture toughness compared to all other teeth bonded to milled denture bases. In the 3D printed groups, the main mode of failure was adhesive at the tooth-bonding material interface. The main mode of failure in the milled teeth groups was cohesive within the bonding material itself. The heat cured groups showed distinct adhesive failure at the tooth-denture base interface.  JUNE 2 0 2 1

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Chung et al.34 conducted an in vitro study that tested the chipping and indirect tensile fracture resistance of five different (3D printed and prefabricated) denture teeth. 3D printed resin teeth revealed comparable fracture resistance to some of the conventionally prefabricated denture teeth used in the study. Goodacre et al.35 conducted an in vitro study that studied the accuracy and reproducibility of prosthesis in regard to tooth movement during fabrication. They found that the milled monolithic technique was the most accurate and reproducible. The least accurate was the injection molding technique and the least reproducible was with the fluid resin technique. More tooth movement was noted for the posterior teeth than anterior teeth across all fabrication techniques, but it was not statistically different. They concluded that varying amounts of tooth movement can be expected and were dependent on the processing technique. However, they reported that the clinical significance of these differences is unknown. Yamamoto et al.36,37 conducted in vitro studies that compared the accuracy of bonded artificial teeth with different offset positions of milled denture bases and shapes of the milled denture teeth. They reported that a milled complete denture needs optimal offsets for accurate teeth position and the optimal offset values differ with the basal shape of different denture teeth. They suggested that dimples in the basal areas of teeth with smooth margins were the most accurate design.

Clinical Outcomes and Patient Satisfaction

Saponaro et al.38 conducted a cross sectional study involving 48 patients. The variables examined were total number of appointments needed to insert the definitive maxillary and mandibular milled

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CDs, the total number of post insertion adjustment visits and any reported complications associated with the level of the clinician’s experience. The results were that the number of appointments at both predoctoral and graduate level was more than the claimed two appointments. No significant differences were found between operator’s experience and the number of appointments required to insert the dentures as well as the complications encountered. The most frequently faced complications reported in this study were the lack of denture retention on

Students preferred the milled CECD because it is easier to perform and there is no laboratory work needed.

the day of denture insertion followed by increased occlusal vertical dimension. In a retrospective survey study by Saponaro et al.,39 questions relevant to their milled CECD experience were distributed to 50 patients with only 19 responding. The factors assessed were patient satisfaction and final outcome. Seventy-eight percent of participating patients reported satisfaction with aesthetics and felt that the new milled dentures were better from their previous conventional CDs though the result was not statistically significant. Srinivasan et al.40 conducted a clinical study that evaluated the clinical chairside time for the predoctoral dental students to fabricate milled dentures and the heat polymerized PMMA resin dentures as well as the general cost for fabricating each

of the denture protocols. The chairside time spent by the student for each patient visit during the entire course of denture construction was timed with a stopwatch and recorded by one investigator. The costs were divided into clinical fees, clinical materials and laboratory costs. Conventional complete denture protocols required significantly longer clinical time than the CECD protocols. In regard to clinical costs, CECDs were more, but overall costs of conventional dentures were significantly higher. Kattadiyil et al.41 conducted a clinical study and evaluated the clinical treatment outcomes (denture base contour, teeth arrangement, fit, retention, extension, stability, aesthetics, lip support and prognosis, occlusal vertical dimension), patient satisfaction and dental student preferences. Each dental student fabricated one set of compression molded denture base and one set of milled dentures. A significantly higher average of overall patient satisfaction and higher preference regarding treatment outcome was seen for the milled CECDs. Students preferred the milled CECD because it is easier to perform and there is no laboratory work needed. No significant difference was found in either patient preference in regard to aesthetics or the student preference in denture technique fabrication without faculty supervision. In a two-year retrospective crosssectional study on 314 patients who were treated in a university setting, Clark et al.42 reported that CECD dentures required fewer appointments to complete treatment and fewer postoperative appointments than conventionally fabricated dentures with statistical significance. However, about 50% of CECD needed four visits to finish. Less than 10% were finished in only two appointments and less than 20% in three appointments. Forty percent of conventional dentures were


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completed in five appointments and about 25% in six appointments. Schlenz et al.43 conducted a retrospective pilot study that evaluated the clinical performance of CECD in regard to survival and maintenance using the two-visit concept. Their result was all CECD survived more than the two-year observational period with no replacement recorded. For 3 out of 10 CECDs made during the initial period, the denture border had to be corrected and one CECD required relining due to inadequate retention. During the functional period, seven CECDs had to be relined and two CECDs fractured. In a prospective study, Cristache et al.44 assessed patient-centered 18-month outcomes of 3D printed dentures using an improved PMMA with nano TiO2. They reported significant reductions in the Oral Health Impact Profile for edentulous patients’ scores for the overall treatment groups registered at one-week, 12-month and 18-month follow-ups. No significant differences were noticed over time (18 months compared to one week). Also, the lowest mean value for the 3D printed dentures was registered at 18 months for aesthetics compared to the satisfactory initial aesthetic assessments. A microcomputed tomography examination showed satisfactory uniformity of the nano TiO2 in the PMMA matrix and no defects such as cracks or pores were seen after 18 months of use. Schwindling and Stober45 performed a pilot clinical trial on five patients to compare the clinical feasibility of milled and milled wax base with injection molding methods for CECDs. Complications during fabrication and quality of the milled and injected CD were reported. There was no difference

in the fit between groups. The retention of the maxillary prostheses was slightly better for the milled CECDs. Aesthetic scores were comparable for both groups. Occlusion was assessed as slightly better for the milled CECDs, although no pronounced differences were reported. They concluded clinical feasibility for both types of fabrication techniques. Bidra et al.46 performed a prospective pilot study to evaluate clinical and patient-related outcomes for monolithic milled CECDs to evaluate any differences in outcomes at baseline and

Participants treated with CECDs took longer to achieve satisfactory levels of comfort, but they took longer to return for unscheduled visits.

and all dentures were intact and in good condition at the one-year follow-up.

Adjustments Needed

Drago et al.47 conducted a clinical study on 106 participants and evaluated the number of unscheduled post insertion visits after the first scheduled appointment and one to two weeks post insertion of the injection molded and milled CDs. The patients were followed up for a year. Of the participants, 22% from both groups returned for at least one unscheduled post insertion adjustment for up to a year. There was no significant difference in the number of unscheduled adjustments, but there was a significant association with the number of unscheduled appointments in patients with single dentures. Participants treated with CECDs took longer to achieve satisfactory levels of comfort, but they took longer to return for unscheduled visits.

Trial Dentures at a 12-month follow up and to identify any adverse clinical and patient-related outcomes related to CECDs. It was found that significant time was spent on the communication process with the laboratory. For patient-related outcomes, significant improvements in participant ratings from baseline to one year were observed regarding absence of denture sore spots and treatment time. Seventynine percent were satisfied with their milled CECDs overall. Fifty percent did not rate their CECDs as good or excellent for retention, stability and adaptation of the bases. For clinical outcomes, the excellent and good ratings for overall assessment by two evaluators was an average of 60%. No adverse clinical or patient-centered outcomes related to the milled CECDs were found,

Wimmer et al.48 conducted a descriptive study evaluating the effect of tooth positioning in milled trial denture bases. The authors concluded that manually positioning the denture teeth into the sockets of the milled trial denture base can result in positional errors. Stawarczyk et al.49 in an in vitro descriptive study compared the accuracy of injection molded denture bases and milled trial denture. The authors reported that both groups showed deviations, but the milled trial dentures showed less deviation.

Applications

As a result of its improved properties, reduced production time and digital archiving, CECDs were used by clinicians to overcome some of the limitations of conventional CD treatment that could be advantageous in certain clinical situations.50–53  JUNE 2 0 2 1

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Systematic Reviews

Bidra et al.54 presented one of the earlier systematic reviews on CECDs in 2012 that focused on the history, current status at the time and the future potential of CECDs. They reported the need for prospective clinical trials to validate the rapidly advancing CECD technology. Wang et al.55 performed a systematic review on the accuracy of CECDs. Selected studies were reporting on adaptation and occlusal discrepancies of milled and 3D printed CECDs. The authors concluded that CECDs have a clinically acceptable range for occlusal trueness (< 1 mm) and denture base adaptation (< 0.3 mm) that is comparable or superior to conventional denture base materials with the greatest misfit in the posterior palatal seal area. However, despite their encouraging findings, the authors cautioned that all articles reviewed had a medium (six articles) to high (eight articles) risk of bias based on their evaluation. In a systematic review on the clinical outcomes and applications of CECDs, Kattadiyil and AlHelal56 reported that the main advantages of utilizing digital technology in complete denture fabrication are digital achievability, improved retention, reduced number of appointments and clinical time. The findings of this review were mainly on milled CECDs. In another systematic review on the clinical complications and the quality assessment factors with CECDs, Kattadiyil et al.57 found that most clinical complications that were identified through the literature were patient dissatisfaction (26%), inadequate retention (21%) and aesthetic concerns (15%). Complications associated with aesthetics, occlusal vertical dimension and centric relation leading to patient overall dissatisfaction could have resulted 388 JUNE

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due to the lack of a trial placement option for CECDs. Furthermore, inconveniency in reading a digital preview was recognized as a unique complication associated with CECDs. The findings of this review were mainly on milled CECDs. Anadioti et al.58 conducted a narrative review investigating the novel biomaterials, fabrication techniques and workflows, clinical performance and patient satisfaction of 3D printed CECDs. Due to the limited data available on 3D printed CECDs and 3D printing technology, the authors recommended

There has been no report to date that has attempted to review available data to provide a consensus statement on the current status of CECDs. that its utilization should be limited to custom tray, record bases, trial, interim and immediate dentures fabrication but not for definitive complete dentures. The authors also listed the main disadvantages of 3D printed CECDs: elimination of trial placement appointment without reliable virtual aesthetic assessment, lack of retention with printed polymers necessitating reline for clinical acceptability, inability to achieve balanced occlusion and lack of long-term color stability affecting denture aesthetics. Main advantages reported were positive patient-related outcomes and improved cost-effectiveness.

Discussion

The literature search revealed that the subtractive (milling) and additive (3D

printing) CECDs have been extensively researched since the inception of the concept. There have been numerous systematic reviews that have reported the trends associated with various aspects of milled and printed CECDs related to material properties, accuracy, clinical outcomes and clinical complication. However, there has been no report to date that has attempted to review available data to provide a consensus statement on the current status of CECDs. Even though the in vitro testing reveals significantly superior adaptation with milled denture bases compared to conventional and printed denture bases, this was not easily discerned in clinical evaluation. The resiliency of the soft tissue could have been a factor for this disparity between clinical and laboratory assessments. The clinical impact of initial superior retention of milled denture bases compared to conventional and printed denture bases has not been assessed over a longer time period. This is probably due to the technical constraints with an ideal study model. Milled denture bases revealed higher material hardness, strength, less roughness, abrasion resistance, increased wettability after polishing and reduced microbial adherence compared to printed and heat processed denture bases. The available data also seem to suggest that milled denture bases are more resistant to staining especially at the toothdenture base interface. Perea-Lowery et al.23 reported milled denture bases did not have better mechanical properties regarding flexural strength, elastic modulus and nanohardness and surface microhardness than conventional denture base materials. This study contradicts results from other studies.22,24,27,28 There is higher initial bond strength to denture teeth for conventional heat cured denture bases compared to milled and


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printed denture bases.33 However, clinical impact of this reduced bond strength among CECDs has not been reported.57 It is expected that due to less wastage and lower costs associated with the 3D printing process, this mode of fabrication will become popular as the technology advances.58 However, sufficient data is lacking currently to arrive at clinically meaningful conclusions. It is interesting to note that the initial introduction of CECDs as a two-appointment process has now been “modified” to a threeappointment protocol among most manufacturers with the “trial placement option.” The introduction of the trial placement option could have been due to increased demand for evaluating and confirming aesthetics, occlusion, phonetics and vertical dimension prior to definitive CECD fabrication. In the early protocols for capturing centric relation (CR), the manufacturers used a Gothic arch tracing to capture centric relation. Most manufacturers now provide an option of using occlusion rims to record CR at the appropriate vertical dimension. The authors expect the technology to evolve to meet the needs and demands of the increasing completely edentulous population that includes but are not limited to quality, function and reduced number of patient visits and fabrication time. A 2016 survey59 of all postdoctoral prosthodontics program directors and prosthodontics/ restorative chairs overseeing predoctoral prosthodontic education in the U.S. related to the degree of implementation of CECDs by the postdoctoral prosthodontic students. The respondents stated that while interested in implementing the digital fabrication of CECDs, only 10% or less of CDs were actually being fabricated using digital technology. It is expected that there will be a higher shift toward CECD fabrication as the growing use of digital technology continues to

increase. The authors also anticipate an increased interest in reducing laboratory procedures among the predoctoral student population due to constraints imposed by the COVID-19 pandemic. The CECD manufacturing technology can be an effective solution to such constraints and might result in increased usage. As usage increases, the environmental impact from CECD manufacturing technology (milling and printing) is a concern and needs to be studied.

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Milled CECDs provide superior adaptation compared to conventional CDs and 3D printed CECDs. However, the improved adaptation of milled denture bases did not result in superior patient satisfaction or clinical experience when compared to conventional or printed dentures. Maxillary CECD denture bases provide increased retention compared to conventional denture bases. Milled denture base materials are reported to have improved physical and surface properties when compared to conventional and 3D printed denture bases. However, there are varying material properties among different CECD manufacturers. Milled denture bases have superior color stability and biocompatibility compared to conventional denture bases. CECD fabrication protocol can reduce chair time and overall costs when compared to conventional CDs. A trial placement appointment before definitive CECD fabrication might assist in a more predictable and favorable outcome.

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Patient satisfaction is not significantly better for CECDs when compared to conventionally fabricated CDs. Clinical studies on long-term benefits with CECDs compared to conventional CDs are lacking. n

RE F E RE N C E S 1. Maeda Y, Minoura M, Tsutsumi S, Okada M, Nokubi T. A CAD/CAM system for removable denture. Part I: Fabrication of complete dentures. Int J Prosthodont Jan–Feb 1994;7(1):17– 21. 2. Kattadiyil MT, Goodacre CJ, Baba NZ. CAD/CAM complete dentures: A review of two commercial fabrication systems. J Calif Dent Assoc 2013 Jun;41(6):407–16. 3. The Glossary of Prosthodontic Terms: Ninth Edition. J Prosthet Dent 2017 May;117(5S):e1–e105. doi: 10.1016/j. prosdent.2016.12.001. 4. Lee S, Hong SJ, Paek J, Pae A, Kwon KR, Noh K. Comparing accuracy of denture bases fabricated by injection molding, CAD/CAM milling and rapid prototyping method. J Adv Prosthodont 2019 Feb;11(1):55–64. doi: 10.4047/ jap.2019.11.1.55. Epub 2019 Feb 26. 5. Yoon HI, Hwang HJ, Ohkubo C, Han JS, Park EJ. Evaluation of the trueness and tissue surface adaptation of CAD-CAM mandibular denture bases manufactured using digital light processing. J Prosthet Dent 2018 Dec;120(6):919–926. doi: 10.1016/j.prosdent.2018.01.027. Epub 2018 Jun 28. 6. Srinivasan M, Cantin Y, Mehl A, Gjengedal H, Muller F, Schimmel M. CAD/CAM milled removable complete dentures: An in vitro evaluation of trueness. Clin Oral Investig 2017 Jul;21(6):2007–2019. doi: 10.1007/s00784-016-1989-7. Epub 2016 Nov 8. 7. McLaughlin JB, Ramos V Jr., Dickinson DP. Comparison of fit of dentures fabricated by traditional techniques versus CAD/ CAM technology. J Prosthodont 2019 Apr;28(4):428–435. doi: 10.1111/jopr.12604. Epub 2017 Nov 14. 8. Hsu CY, Yang TC, Wang TM, Lin LD. Effects of fabrication techniques on denture base adaptation: An in vitro study. J Prosthet Dent 2020 Dec 124(6):740–47. doi.org/10.1016/j. prosdent.2020.02.012. 9. Steinmassl O, Dumfahrt H, Grunert I, Steinmassl PA. CAD/ CAM produces dentures with improved fit. Clin Oral Investig 2018 Nov;22(8):2829–2835. doi: 10.1007/s00784-0182369-2. Epub 2018 Feb 22. 10. Yoon SN, Oh KC, Lee SJ, Han JS, Yoon HI. Tissue surface adaptation of CAD-CAM maxillary and mandibular complete denture bases manufactured by digital light processing: A clinical study. J Prosthet Dent 2020 Dec;124(6):682–689. doi: 10.1016/j.prosdent.2019.11.007. Epub 2020 Jan 8. 11. Goodacre BJ, Goodacre CJ, Baba NZ, Kattadiyil MT. Comparison of denture base adaptation between CAD-CAM and conventional fabrication techniques. J Prosthet Dent 2016 Aug;116(2):249–56. doi: 10.1016/j.prosdent.2016.02.017. Epub 2016 Apr 23. 12. Kalberer N, Mehl A, Schimmel M, Muller F, Srinivasan M. CAD-CAM milled versus rapidly prototyped (3D printed) complete dentures: An in vitro evaluation of trueness. J  JUNE 2 0 2 1

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Prosthet Dent 2019 Apr;121(4):637–643. doi: 10.1016/j. prosdent.2018.09.001. Epub 2019 Jan 31. 13. Tasaka A, Matsunaga S, Odaka K, Ishizaki K, Ueda T, Abe S, et al. Accuracy and retention of denture base fabricated by heat curing and additive manufacturing. J Prosthodont Res 2019;63(1):85–9. 2019 Jan;63(1):85–89. doi: 10.1016/j. jpor.2018.08.007. Epub 2018 Dec 21. 14. AlHelal A, AlRumaih HS, Kattadiyil MT, Baba NZ, Goodacre CJ. Comparison of retention between maxillary milled and conventional denture bases: A clinical study. J Prosthet Dent 2017 Feb;117(2):233–238. doi: 10.1016/j. prosdent.2016.08.007. Epub 2016 Oct 17. 15. AlRumaih HS, AlHelal A, Baba NZ, Goodacre CJ, AlQahtani A, Kattadiyil MT. Effects of denture adhesive on the retention of milled and heat-activated maxillary denture bases: A clinical study. J Prosthet Dent 2018 Sep;120(3):361–366. doi: 10.1016/j.prosdent.2017.10.013. Epub 2018 Mar 15. 16. Aguirre BC, Chen JH, Kontogiorgos ED, Murchison DF, Nagy WW. Flexural strength of denture base acrylic resins processed by conventional and CAD-CAM methods. J Prosthet Dent 2020 Apr;123(4):641–646. doi: 10.1016/j. prosdent.2019.03.010. Epub 2019 Jul 26. 17. Steinmassl O, Offermanns V, Stockl W, Dumfahrt H, Grunert I, Steinmassl PA. In vitro analysis of the fracture resistance of CAD/CAM denture base resins. Materials (Basel) 2018 Mar 8;11(3):401. doi: 10.3390/ma11030401. 18. Srinivasan M, Gjengedal H, Cattani-Lorente M, Moussa M, Durual S, Schimmel M, et al. CAD/CAM milled complete removable dental prostheses: An in vitro evaluation of biocompatibility, mechanical properties and surface roughness. Dent Mater J 2018 Jul 29;37(4):526–533. doi: 10.4012/ dmj.2017-207. Epub 2018 Mar 6. 19. Ayman AD. The residual monomer content and mechanical properties of CAD/CAM resins used in the fabrication of complete dentures as compared to heat cured resins. Electron Physician 2017 Jul 25;9(7):4766–4772. doi: 10.19082/4766. eCollection 2017 Jul. 20. Einarsdottir ER, Geminiani A, Chochlidakis K, Feng C, Tsigarida A, Ercoli C. Dimensional stability of double-processed complete denture bases fabricated with compression molding, injection molding and CAD-CAM subtraction milling. J Prosthet Dent 2020;124(1):116–21. doi.org/10.1016/j. prosdent.2019.09.011. 21. Prpić V, Schauperl Z, Catic A, Dulcic N, Cimic S. Comparison of mechanical properties of 3D-printed, CAD/ CAM and conventional denture base materials. J Prosthodont 2020;29(6):524–8. doi.org/10.1111/jopr.13175. 22. Al-Dwairi ZN, Tahboub KY, Baba NZ, Goodacre CJ. A comparison of the flexural and impact strengths and flexural modulus of CAD/CAM and conventional heat-cured polymethyl methacrylate (PMMA). J Prosthodont 2020 Apr;29(4):341–349. doi: 10.1111/jopr.12926. Epub 2018 Jun 13. 23. Perea-Lowery L, Minja IK, Lassila L, Ramakrishnaiah R, Vallittu PK. Assessment of CAD-CAM polymers for digitally fabricated complete dentures. J Prosthet Dent 2021 Jan;125(1):175–181. doi: 10.1016/j.prosdent.2019.12.008. Epub 2020 Feb 14. 24. Al-Dwairi ZN, Tahboub KY, Baba NZ, Goodacre CJ, Ozcan M. A comparison of the surface properties of CAD/ CAM and conventional polymethylmethacrylate (PMMA). J Prosthodont 2019 Apr;28(4):452–457. doi: 10.1111/ jopr.13033. Epub 2019 Feb 19.

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25. Alammari MR. The influence of polishing techniques on prepolymerized CAD/CAM acrylic resin denture bases. Electron Physician 2017 Oct;9(10):5452–8. doi: 10.19082/5452. 26. Al-Fouzan AF, Al-Mejrad LA, Albarrag AM. Adherence of Candida to complete denture surfaces in vitro: A comparison of conventional and CAD/CAM complete dentures. J Adv Prosthodont 2017 Oct;9(5):402–408. doi: 10.4047/ jap.2017.9.5.402. Epub 2017 Oct 16. 27. Shinawi LA. Effect of denture cleaning on abrasion resistance and surface topography of polymerized CAD CAM acrylic resin denture base. Electron Physician 2017 May 25;9(5):4281–4288. doi: 10.19082/4281. eCollection 2017 May. 28. Totu EE, Nechifor AC, Nechifor G, Aboul-Enein HY, Cristache CM. Poly(methyl methacrylate) with TiO2 nanoparticles inclusion for stereolitographic complete denture manufacturing — the future in dental care for elderly edentulous patients? J Dent 2017 Apr;59:68–77. doi: 10.1016/j. jdent.2017.02.012. Epub 2017 Feb 20. 29. Steinmassl O, Dumfahrt H, Grunert I, Steinmassl PA. Influence of CAD/CAM fabrication on denture surface properties. J Oral Rehabil 2018 May;45(5):406–413. doi: 10.1111/joor.12621. Epub 2018 Mar 9. 30. Arslan M, Murat S, Alp G, Zaimoglu A. Evaluation of flexural strength and surface properties of prepolymerized CAD/CAM PMMA-based polymers used for digital 3D complete dentures. Int J Comput Dent 2018;21(1):31–40. 31. Al-Qarni FD, Goodacre CJ, Kattadiyil MT, Baba NZ, Paravina RD. Stainability of acrylic resin materials used in CAD-CAM and conventional complete dentures. J Prosthet Dent 2020 Jun;123(6):880–887. doi: 10.1016/j. prosdent.2019.07.004. Epub 2019 Nov 5. 32. Cha HS, Park JM, Kim TH, Lee JH. Wear resistance of 3D-printed denture tooth resin opposing zirconia and metal antagonists. J Prosthet Dent 2020;124(3):387–94. doi. org/10.1016/j.prosdent.2019.09.004. 33. Choi JJE, Uy CE, Plaksina P, Ramani RS, Ganjigatti R, Waddell JN. Bond strength of denture teeth to heat-cured, CAD/CAM and 3D printed denture acrylics. J Prosthodont 2020 Jun;29(5):415–421. doi: 10.1111/jopr.13125. Epub 2019 Nov 19. 34. Chung YJ, Park JM, Kim TH, Ahn JS, Cha HS, Lee JH. 3D printing of resin material for denture artificial teeth: Chipping and indirect tensile fracture resistance. Materials (Basel) 2018 Sep 21;11(10):1798. doi: 10.3390/ma11101798. 35. Goodacre BJ, Goodacre CJ, Baba NZ, Kattadiyil MT. Comparison of denture tooth movement between CAD-CAM and conventional fabrication techniques. J Prosthet Dent 2018 Jan;119(1):108–115. doi: 10.1016/j.prosdent.2017.02.009. Epub 2017 May 12. 36. Yamamoto S, Kanazawa M, Iwaki M, Jokanovic A, Minakuchi S. Effects of offset values for artificial teeth positions in CAD/CAM complete denture. Comput Biol Med 2014 Sep;52:1–7. doi: 10.1016/j.compbiomed.2014.05.011. Epub 2014 Jun 7. 37. Yamamoto S, Kanazawa M, Hirayama D, Nakamura T, Arakida T, Minakuchi S. In vitro evaluation of basal shapes and offset values of artificial teeth for CAD/CAM complete dentures. Comput Biol Med 2016 Jan 1;68:84–9. doi: 10.1016/j.compbiomed.2015.11.004. Epub 2015 Nov 19. 38. Saponaro PC, Yilmaz B, Heshmati RH, McGlumphy EA. Clinical performance of CAD-CAM-fabricated complete dentures: A cross-sectional study. J Prosthet Dent 2016

Sep;116(3):431–5. doi: 10.1016/j.prosdent.2016.03.017. Epub 2016 May 7. 39. Saponaro PC, Yilmaz B, Johnston W, Heshmati RH, McGlumphy EA. Evaluation of patient experience and satisfaction with CAD-CAM-fabricated complete dentures: A retrospective survey study. J Prosthet Dent 2016 Oct;116(4):524–528. doi: 10.1016/j. prosdent.2016.01.034. Epub 2016 Jul 9. 40. Srinivasan M, Schimmel M, Naharro M, O’Neill C, McKenna G, Muller F. CAD/CAM milled removable complete dentures: Time and cost estimation study. J Dent 2019 Jan;80:75–79. doi: 10.1016/j.jdent.2018.09.003. Epub 2018 Sep 10. 41. Kattadiyil MT, Jekki R, Goodacre CJ, Baba NZ. Comparison of treatment outcomes in digital and conventional complete removable dental prosthesis fabrications in a predoctoral setting. J Prosthet Dent 2015 Dec;114(6):818– 25. doi: 10.1016/j.prosdent.2015.08.001. Epub 2015 Sep 26. 42. Clark WA, Brazile B, Matthews D, Solares J, De Kok IJ. A comparison of conventionally versus digitally fabricated denture outcomes in a university dental clinic. J Prosthodont 2020 Oct. doi.org/10.1111/jopr.13273. 43. Schlenz MA, Schmidt A, Wostmann B, Rehmann P. Clinical performance of computer-engineered complete dentures: A retrospective pilot study. Quintessence Int 2019;50(9):706– 711. doi: 10.3290/j.qi.a42778. 44. Cristache CM, Totu EE, Iorgulescu G, Pantazi A, Dorobantu D, Nechifor AC, et al. Eighteen months follow-up with patient-centered outcomes assessment of complete dentures manufactured using a hybrid nanocomposite and additive CAD/CAM protocol. J Clin Med 2020 Jan 23;9(2):324. doi: 10.3390/jcm9020324. 45. Schwindling FS, Stober T. A comparison of two digital techniques for the fabrication of complete removable dental prostheses: A pilot clinical study. J Prosthet Dent 2016 Nov;116(5):756–763. doi: 10.1016/j. prosdent.2016.03.022. Epub 2016 May 26. 46. Bidra AS, Farrell K, Burnham D, Dhingra A, Taylor TD, Kuo CL. Prospective cohort pilot study of 2-visit CAD/ CAM monolithic complete dentures and implant-retained overdentures: Clinical and patient-centered outcomes. J Prosthet Dent 2016 May;115(5):578–586.e1. doi: 10.1016/j.prosdent.2015.10.023. Epub 2016 Jan 13. 47. Drago C, Borgert AJ. Comparison of nonscheduled, postinsertion adjustment visits for complete dentures fabricated with conventional and CAD-CAM protocols: A clinical study. J Prosthet Dent 2019 Nov;122(5):459–466. doi: 10.1016/j. prosdent.2018.10.030. Epub 2019 Jun 12. 48. Wimmer T, Eichberger M, Lumkemann N, Stawarczyk B. Accuracy of digitally fabricated trial dentures. J Prosthet Dent 2018 Jun;119(6):942–947. doi: 10.1016/j. prosdent.2017.06.020. Epub 2017 Sep 29. 49. Stawarczyk B, Lumkemann N, Eichberger M, Wimmer T. Accuracy of digitally fabricated wax denture bases and conventional completed complete dentures. Dent J (Basel) 2018 Jun;119(6):942–947. doi: 10.1016/j. prosdent.2017.06.020. Epub 2017 Sep 29. 50. Millet C, Ducret M, Khoury C, Virard F. Monolithic CAD/ CAM complete overdentures for a pedodontic patient with dentinogenesis imperfecta and limited prosthetic space: A clinical report. Int J Prosthodont May/Jun 2020;33(3):341– 346. doi: 10.11607/ijp.6563.


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51. Punj A, Kattadiyil MT. Management of ectodermal dysplasia with tooth-supported computer-engineered complete overdentures: A clinical report. J Prosthet Dent 2019 Feb;121(2):195–199. doi: 10.1016/j. prosdent.2018.03.011. Epub 2018 Aug 20. 52. Bidra AS. The 2-visit CAD-CAM implant-retained overdenture: A clinical report. J Oral Implantol 2014 Dec;40(6):722–8. doi: 10.1563/AAID-JOI-D-12-00237. 53. Lozada JL, Garbacea A, Goodacre CJ, Kattadiyil MT. Use of a digitally planned and fabricated mandibular complete denture for easy conversion to an immediately loaded provisional fixed complete denture. Part 1. Planning and surgical phase. Int J Prosthodont Sep-Oct 2014;27(5):417– 21. doi: 10.11607/ijp.3825. 54. Bidra AS, Taylor TD, Agar JR. Computer-aided technology for fabricating complete dentures: Systematic review of historical background, current status and future perspectives. J Prosthet Dent 2013 Jun;109(6):361–6. doi: 10.1016/ S0022-3913(13)60318-2. 55. Wang C, Shi YF, Xie PJ, Wu JH. Accuracy of digital complete dentures: A systematic review of in vitro studies. J Prosthet Dent 2021 Feb;125(2):249–256. doi: 10.1016/j.

prosdent.2020.01.004. Epub 2020 Feb 27. 56. Kattadiyil MT, AlHelal A. An update on computerengineered complete dentures: A systematic review on clinical outcomes. J Prosthet Dent 2017 Apr;117(4):478–485. doi: 10.1016/j.prosdent.2016.08.017. Epub 2016 Oct 27. 57. Kattadiyil MT, AlHelal A, Goodacre BJ. Clinical complications and quality assessments with computerengineered complete dentures: A systematic review. J Prosthet Dent 2017 Jun;117(6):721–728. doi: 10.1016/j. prosdent.2016.12.006. Epub 2017 Feb 20. 58. Anadioti E, Musharbash L, Blatz MB, Papavasiliou G, Kamposiora P. 3D printed complete removable dental prostheses: A narrative review. BMC Oral Health 2020;20(1):343. 59. Fernandez MA, Nimmo A, Behar-Horenstein LS. Digital denture fabrication in pre- and postdoctoral education: A survey of U.S. dental schools. J Prosthodont 2016 Jan;25(1):83–90. doi: 10.1111/jopr.12287. Epub 2015 Jun 22. TH E CO RRE S P ON DIN G AU T HOR, Sarah Bukhari, BDS, MS, can be reached at sbukhari@llu.edu.

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denture aesthetics C D A J O U R N A L , V O L 4 9 , Nº 6

Complete Denture Aesthetics Revisited in the Digital Age Steven J. Sadowsky, DDS

abstract Background: The objective of this review is to elucidate the principles of complete denture aesthetics and establish a rationale for a digital workflow for chairside arrangement of artificial teeth. Types of studies reviewed: Articles were culled on the topic of complete denture aesthetics and the digital fabrication of complete dentures. These included systematic and literature review articles as well as clinical, descriptive and in vitro studies that range from 1958 to 2020 using PubMed and Web of Science databases. Results: Biometric measurements have been illuminated over the last 60 years, serving as a basis for analogue and digital denture aesthetics. However, a number of studies have shown that individual arrangement of the anterior teeth is essential to capture asymmetry and balance in the setup. This review highlights that customization of the smile is optimally done chairside with patient feedback. A proof of concept was identified from the literature to incorporate a wax try-in in the digital workflow. Practical implications: Given the heightened value placed on aesthetics in dentistry, a review of complete denture aesthetics will enhance the clinician’s skillset, and incorporating a chairside try-in in the digital workflow will lead to more authentic prostheses. Key words: Complete denture aesthetics, biometrics, digital dentures

AUTHOR Steven J. Sadowsky, DDS, is professor in the department of preventive and restorative dentistry at the University of the Pacific, Arthur A. Dugoni School of Dentistry. He is a diplomate of the American Board of Prosthodontists and sits on the editorial review boards of the Journal of Prosthetic Dentistry, the International Journal of Oral and Maxillofacial Implants

and the International Journal of Prosthodontics. He is the abstract editor of the International Journal of Prosthodontics and has been appointed to the editorial council of the Journal of Prosthetic Dentistry. Conflict of Interest Disclosure: None reported.

A

digital approach to fabricating complete dentures has offered clinicians a more efficient fabrication process enlisting computer-aided design and computer-aided manufacturing (CAD/ CAM) technology for milled and printed dentures.1,2 The advent of 3D facial scanning (3DFS) and designing technology has facilitated a virtual clinical evaluation of the aesthetic denture setup.3 There are notable advantages to using

a digital approach with 3DFS. The 3D libraries for teeth are quite exhaustive with 3,500 denture teeth and 380 tooth mould libraries available, including wellknown companies such as Myerson, Vita, Shofu, Candulor, Kulzer and Dentsply. You can download any library with an exocad serial number and a valid email address. A permanent exocad DentalCAD license with a currently active upgrade contract or an exocad DentalCAD/ ChairsideCAD/exoplan Flex License  JUNE 2 0 2 1

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tooth arrangement and aesthetics, improving patient satisfaction and reducing remake of the dentures. FIGURE 1A . Monoblock 3D printed dentures. (Courtesy of Majed Altoman, BDS, MSc.)

FIGURE 2A . Digitized STL file of denture base. (Courtesy of Kris Schermerhorn, CDT.)

is needed. A virtual teeth setup permits efficient adjustments of midline, tooth size and position and generalized adjustments to the facial appearance and occlusal plane. In addition, the virtual setup is digitally stored, reducing the time and cost of replacement. However, there are several drawbacks to this technology. While stereophotogrammetric systems demonstrate accuracy and reliability in the collection of 3D facial scans, their cost, size and complexity make them unsuitable for most clinical practices. Further improvements in their technical specifications are also needed. For example, the alignment of the neutral smile and cheek retractor scans depend on the stability of the forehead as a reference. In patients with excessive facial grooves, this region can deform when smiling, hindering an accurate registration. Other errors have been reported due to movement during the scan, salivary flow and facial hair as well as the differences in technology used by each scanner.3,4 Moreover, multiple factors are best evaluated chairside. The measurement of the vertical dimension of occlusion, centric relation and closest speaking space requires an animated patient and will impact function and phonetics.5 394 JUNE

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FIGURE 1B . Analogue try-in of monoblock dentures. (Courtesy of Majed Altoman, BDS, MSc.)

Proof of Concept To Offer the Clinician an Adjustable Analogue Try-in in the Digital Workflow

While a number of authors7–9 have reported on rapid prototyping (RP) complete dentures, Chen et al.10 have quantitatively evaluated a wax pattern of a maxillary complete denture using a plaster cast and CAD software to program a 3D wax printer (ProJet CPX 3500, 3D Systems, Rock Hill, S.C.). There FIGURE 2B . Digitized STL file of denture teeth. (Courtesy of Kris Schermerhorn, CDT.) was no significant difference between the 3D printed group and the analogue Virtual changes in the anterior tooth group for measurements of deviation setup offer the patient only a semblance of between the denture tissue surface and the final aesthetic arrangement of teeth. the plaster cast. This research has offered A monolithic analogue (monoblock) the prospect of an accurate, adjustable denture try-in is limited in its utility for waxed base from a Standard Tessellation individualization and assessing patient Language (STL) file (FIGURE 2A ) to satisfaction (FIGURES 1). The importance place on individual RP denture teeth from of showing the patient a midline change, a second STL file (FIGURE 2B ). When correction of canted incisal plane, impact of position changes are made chairside, the a colored gingival matrix display, aesthetic corrections can be scanned to digitize the effect of rotation of lateral incisors and new denture’s cameo surface and artificial opening up of incisal embrasures all are teeth.11 This can then be used for a CAD/ critical. The ability to test out changes in CAM application as well.12,13 Given the real time chairside is critical to an aesthetic premium on an attractive smile and its link and phonetic evaluation. The need for an in- to success as well as heightened patient person adjustable denture try-in within the expectations, a review of complete denture digital workflow has clearly been established. aesthetics will underscore the importance of Using computer-engineered complete a chairside try-in appointment in the digital denture (CECD), a systematic review workflow to enhance a customized setup. assessed patient satisfaction using digital libraries and a virtual try-in.6 They Individualizing a Patient’s Smile concluded that 25% of patients were Nature and enduring art are dissatisfied with the overall outcome thematically based in balance and and 15% were unhappy with the asymmetry. Balance creates the appearance aesthetics. Their recommendation was of symmetry and sets up a dynamic tension the addition of a trial placement option and vitality that mimics all that is alive. for CECDs could result in improved In the natural dentition, symmetry in the clinical outcome, reducing the incidence anterior sextant is found only in 10% to of other complications such as occlusal 14% of subjects (FIGURE 3 ).14 The mouth vertical dimension, centric relation, should be a subset of the face. It should


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FIGURE 3 . Asymmetry and balance in the natural

dentition.

also have a midline that separates two non-mirror-like images within the outline of the lips. Lombardi called this dynamic unity and applied it to the prosthetic arrangement of anterior teeth.15 Frush and Fisher coined the term “dynesthetic” to reflect the power and vitality of a smile when it is customized to reflect the patient’s individuality, considering sex (gender), personality and age.16 The attribution of gender in an anterior setup is not simply to reflect whether the patient is a male or female. In fact, neither experts in dentistry nor laypeople were able to identify a sexual dimorphism from photographs of a smile when the lips were covered.17,18 Instead, the use of lapping of the lateral incisors and rounding of the incisal edge reveal a softness (FIGURE 4 ), while a frontal display of lateral incisors and a flat incisal edge confers a boldness, based on a gestalt of the patient (FIGURE 5 ). Similarly, a delicate or a vigorous personality can be depicted by a mesial or vertical axial inclination of the cuspids. Finally, age is the fourth dimension of a tooth setup which is reflected in a linear wear of the incisal edge over the life of the individual. Males and females show similar rates of tooth wear. Maxillary central incisors wear 1 mm by the age of 70, while the mandibular central incisors wear 1.5 mm.19 Incorporating timerelated changes in the incisal length bestows an authenticity to the smile (FIGURE 6).

Biometric Guides

Biometric guides have been suggested for selecting the width of the maxillary central incisor (CW). The ratio of the interpupillary distance (IPD) and CW in a pre-extraction smiling photograph

FIGURE 4 . The lapping of lateral incisors and rounded incisal edges lend a soft appearance to a male patient.

can be implemented when measuring the patient’s IPD to establish the CW (FIG URES 7 ). When an archival photograph is not available, the appropriate maxillary anterior tooth size can be estimated by anthropometric measurements. Cesario and Latta20 found a reliable correlation between the interpupillary distance divided by 6.6 for CW (FIGURE 8A ). Using the inner canthal distance multiplied by a geometric proportion of 0.618 divided by 2 has also been found to be a reliable predictor for CW (FIGURE 8B ).21 The bizygomatic width divided by 16 has been suggested to be predictive of the CW, although correlation coefficients have been found to be low for this face:tooth ratio.22 However, a recent systematic review indicated that the combined width of the maxillary central incisors can be forecast by multiplying the interalar distance (IAD) by 70%.23 In this same study, neither the IAD or the inner canthal distance were reliable guides to predict intercuspid distance. The golden proportion (1.618 to 1) also has not been proven to be predictive between perceived maxillary anterior teeth widths.24 Moreover, in only 25% of patients with a natural dentition is the CW in golden proportion to the mandibular incisor width.25 Regarding the ratio of incisal length to mesial/distal

FIGURE 5 . A bold arrangement of the central

incisors and use of posterior gold onlays in a female patient.

FIGURE 6 . Age-relevant changes in incisal length of

central and lateral incisors.

length of the maxillary central incisor, anthropometric measurements have been found to be predictive. Giddon et al.26 reported a significant correlation in the ratio of the left fourth digit and the right second digit of the hand. Finally, facial height is both a functional and an aesthetic consideration and has been correlated to the width of four fingers (FIGURE 9 ).27 Facial shape has often been ascribed to sexual dimorphism and the impact of testosterone or estrogen but has also been shown to correlate to the second:fourth digit ratio.28 The link between facial form and tooth mold has long been a focus of complete denture practitioners.  JUNE 2 0 2 1

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association and noted that the ovoid tooth form was most prevalent and the square tooth form was least common.30 Perhaps, more importantly, when the width/height ratio of the maxillary central incisor is 85%, it is considered to be optimally aesthetic.31

Arrangement

FIGURE 7A . Photograph of patient when she was 50 years younger helped to establish a ratio of interpupillary distance to maxillary central incisor width.

FIGURE 7B . Measurement of actual interpupillary distance on the patient’s face to reveal the actual maxillary central incisor width.

FIGURE 8A . Anthropometric measurement of interpupillary distance/6.6 for maxillary central incisor width.

FIGURE 8B . Anthropometric measurement of intercanthal width (.618)/2 for maxillary central incisor width.

Mold

FIGURE 9. Anthropometric measurement of width of four fingers for lower third facial height.

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Mavroskoufis and Ritchie29 evaluated Williams’ “law of harmony” that says facial form can predict a square, tapering or ovoid tooth form. The results of their investigation invalidated this method of mold selection because more than two-thirds of the subjects showed a dissimilarity between face and maxillary central incisor form. A corroborating study using AutoCAD software also found no significant tooth mold/facial form

The placement of the maxillary central incisors is of paramount importance. If they are well positioned, all other teeth will be more nearly correct. They also dictate the midline. A parallel discrepancy of the dental midline with the facial midline of 2 mm or more is likely to be noticed by laypeople and reduce attractiveness (FIGURE 10 ). When the dental midline is canted in relation to the facial midline, it creates an even more uncomfortable visual tension and discrepancies of 10% were viewed as unaesthetic by 40% of laypeople.32 Use of floss to bisect the face will facilitate a coincident midline. Using landmarks such as the labial frenum, nasopalatine papilla and midpalatal suture has been identified as reliable in 70% of subjects, but the range of those outside this percent was as much as 5.5 mm from the facial midline.33 This limits an assessment without a try-in. The ultimate position of the maxillary central incisors is dependent on phonetic and aesthetic determinants. The incisal edge of the central incisor should contact the vermillion border of the lower lip when enunciating fricative (F) sounds.34 Appropriate buccolingual position of the maxillary central incisors is essential to create a natural lip drape, as the middle third of the tooth is mainly responsible for scaffolding the upper lip. This assumes that in the impression phase a natural contour is developed in the labial flange region. There is also an aesthetic benefit of rotational and positional variance between the maxillary central incisors, which enhances the appearance of


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vitality by different light reflections and produces natural asymmetry.16 The length discrepancy between the maxillary central and lateral incisor seen in a patient at age 30 may be eclipsed by age 70 because of wear. The display of the maxillary central incisors in respect to the lip at rest also changes with age. A young man or woman displays 2 mm to 3 mm of incisal edge below the lip, respectively, and an aged individual may have incisal edges up to 2 mm above the lip at rest.35 This is due to increased perioral flaccidity, genetics and sunlight exposure. The maxillary lateral incisors show more variation in form and position than any other tooth. Rotation, pitch, forward/backward placement and axial deviation can be used to create dynamic unity.16 By rotating the lateral incisors, the incisal embrasure is increased, which lends individuality and a figureground interplay with light and shadow (FIGURE 11 ). The speaking line is another assessment of the proper display of the lateral incisors, which should be partially visible during speech (FIGURE 12 ).36 The maxillary cuspids are the transition teeth between the anterior and posterior setup. Their distal slope should not be visible in the frontal plane, as the incisal edge points to the central fossa of the posterior quadrant. The cervical aspect is everted in a typical canine eminence and the incisal edge is slightly tucked in. A vertical axial inclination would depict a more vigorous personality (FIGURE 13 ), while a mesial inclination reflects a softer affect. The cuspid should be abraded at the tip in an aging patient. The cuspids complete the anterior sextant and the incisal edges should follow the envelope of the smiling lower lip, whether arcuate or straight (FIGURES 14 ). Looking into a mirror with the patient allows the clinician to visualize the perceived setup, which is different from the observer’s view.

FIGURE 10 . Parallel midline discrepancy of 2 mm

FIGURE 11. Rotation of lateral incisors to open the

identified with a line bisecting the face and coincident with the central tubercle of lip.

incisal embrasures and accentuate interplay of light and shadow.

FIGURE 12 . Fricative sound approximating the maxillary central incisors to vermillion border of lower lip.

FIGURE 13 . Vertical position of cuspids reflecting a bolder personality.

Confirmation of Position of Maxillary and Mandibular Anterior Teeth

mandibular anterior teeth visible and no display of the maxillary sextant.38 Thus, with age, the natural appearance of the mandibular anterior teeth becomes more crucial. Because of their similarity in size and shape, the mandibular incisors must be varied in their axial orientation to appear realistic. Plastic artificial teeth can also be stained on the incisal edge to add

There is a gradual shift in the display of the maxillary and mandibular anterior teeth with age; the exception is patients with Class II malocclusions.37 Patients aged 30 display approximately 0.5 mm of the mandibular incisors at rest. This changes by age 60 with about 3 mm of the

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denture aesthetics C D A J O U R N A L , V O L 4 9 , Nº 6

FIGURE 14A . Incisal edges follow arcuate envelope

FIGURE 14B . Incisal edges follow straight envelope

of lower lip.

of lower lip.

FIGURE 15 . Staggered position of mandibular anterior teeth with incisal stain.

FIGURE 16 . Canted plane of occlusion in relation to interpupillary line.

be disclosed simply when the clinician extends the patient’s commissures with the forefingers in a parallel plane with the interpupillary line so that the anterior and posterior planes can be visualized (FIGURE 16 ). Anteriorly, aesthetic considerations should define the occlusal plane; posteriorly, the tongue, retromolar pad and Stenson’s duct have been used as landmarks. Using the ala-tragus line (Camper’s line) to establish the occlusal plane is also well documented, and Nayar et al.40 found that the inferior border of the tragus to the ala is parallel to the occlusal plane in most dentate subjects. The buccal corridor will affect the attractiveness of a smile. As the amount of buccal corridor display was increased (FIGURE 17A ), smiling images were scored less appealing by the evaluators (FIGURE 17 A ).41 Conversely, when there is an absence of the buccal corridor, there is a loss of perspective and realism (FIGURE 17B ).42

The Gingival Matrix or Visible Denture Base

unaesthetic.

FIGURE 17A . Excessive buccal corridor judged as

FIGURE 17B . Insufficient buccal corridor compromising realism.

reality to wear faceting (FIGURE 15 ). Once the mandibular anterior teeth are set in wax, a phonetic confirmation of their correct position can be confirmed by articulating sibilant (S) sounds. Seventyfive percent of the population produces a sibilant sound by approximating the maxillary and mandibular anterior teeth to within 1 mm.39 The anterior teeth should also approximate an end-to-end position when the patient says “judge.” Of all sounds, sibilants induce the most superior positioning of the mandible

to the maxilla and are considered the “closest speaking space.”5 When the vertical dimension of occlusion encroaches on the vertical dimension of rest, the teeth will contact. This becomes a functional impediment but also affects facial aesthetics with a strained appearance. The incisal/occlusal plane and buccal corridor are also aesthetic factors. When the plane is canted in respect to the interpupillary line, it is a distraction from facial harmony. This relationship can

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Interdental papilla should follow the following precepts: It should be convex and self-cleansing. The shape of the papilla should be a complementary factor in age interpretation with more recession seen in older patients. Diastemas between the anterior teeth and posterior teeth must be V-shaped to shed food. When completing the waxup, flossing interproximally eliminates wax between teeth that otherwise would be processed, resulting in a compromise of the individuality of the setup. The gingival margin of the central incisors must be leveled or slightly coronal to the cuspids and leveled or slightly apical to the lateral incisors. When the base is visible, characterization will add authenticity.43 This completes the refinement of a prosthodontic service that merges physiologic and psychologic comfort.44


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Conclusion

Biometric guides for placement of artificial teeth for complete-denture patients are useful to create harmony and proportion in the anterior setup. However, the dynamism that can be reflected in personalizing a patient’s smile is the result of careful chairside arrangement of individual teeth following the tenets of balance and asymmetry published over 60 years ago. The literature elucidating complete denture aesthetics has had the longest half-life of relevance compared to any other discipline in dentistry. This remains true in the wake of the digital revolution. n RE FEREN CE S 1. Masri G, Mortada R, Ounsi H, et al. Adaptation of complete denture base fabricated by conventional, milling and 3D printing techniques: An in vitro study. J Contemp Dent Pract 2020 Apr 1;21(4):367–71. 2. Anadioti E, Musharbash L, Blatz MB, Papavasiliou G, Kamposiora P. 3D printed complete removable dental prostheses: A narrative review. BMC Oral Health 2020 Nov 27;20(1):343. doi: 10.1186/s12903-020-01328-8. 3. Hassan B, Greven M, Wismeijer D. Integrating 3D facial scanning in a digital workflow to CAD/CAM design and fabricate complete dentures for immediate total mouth rehabilitation. J Adv Prosthodont 2017 Oct;9(5):381–386. doi: 10.4047/ jap.2017.9.5.381. Epub 2017 Oct 16. 4. Amornvit P, Sanohkan S. The accuracy of digital face scans obtained from 3D scanners: An in vitro study. Int J Environ Res Public Health 2019 Dec 12;16(24):5061. doi: 10.3390/ ijerph16245061. 5. Pound E. Let /S/ be your guide. J Prosthet Dent 1977 Nov;38(5):482–9. doi: 10.1016/0022-3913(77)90022-1. 6. Kattadiyil MT, AlHelal A, Goodacre BJ. Clinical complications and quality assessments with computer-engineered complete dentures: A systematic review. J Prosthet Dent 2017 Jun;117(6):721–728. doi: 10.1016/j.prosdent.2016.12.006. Epub 2017 Feb 20. 7. Wang C, Shi YF, Xie PJ, Wu JH. Accuracy of digital complete dentures: A systematic review of in vitro studies. J Prosthet Dent 2021 Feb;125(2):249–256. doi: 10.1016/j. prosdent.2020.01.004. Epub 2020 Feb 27. 8. Kalberer N, Mehl A, Schimmel M, Muller F, Srinivasan M. CAD-CAM milled versus protyped (3D printed) complete dentures: An in vitro evaluation of trueness. J Prosthet Dent 2019 Apr;121(4):637–643. doi: 10.1016/j.prosdent.2018.09.001. Epub 2019 Jan 31. 9. Alharbi N, Wismeijer D, Osman RB. Additive manufacturing techniques in prosthodontics: Where do we currently stand? A critical review. Int J Prosthodont Sep–Oct 2017;30(5):474–484. doi: 10.11607/ijp.5079. Epub 2017 Jul 27. 10. Chen H, Wang H, Lv P, Wang Y, Sun Y. Quantitative evaluation of tissue surface adaption of CAD-Designed and 3D printed wax pattern of maxillary complete denture. Biomed Res Int

2015;2015:453968. doi: 10.1155/2015/453968. Epub 2015 Oct 25. 11. Lee SY, Kim H, Lee D, Park C. Modified digital workflow for artificial tooth exchange in a complete denture: A digital technique. J Prosthet Dent 2020 Feb;123(2):236–238. doi: 10.1016/j. prosdent.2019.03.007. Epub 2019 May 16. 12. Steinmassl O, Dumfahrt H, Grunert I, Steinmassl PA. CAD/ CAM produces dentures with improved fit. Clin Oral Investig 2018 Nov;22(8):2829–2835. doi: 10.1007/s00784-018-2369-2. Epub 2018 Feb 22. 13. Srinivasan M, Kalberer N, Naharro M, Marchand L, Lee H, Müller F. CAD-CAM milled dentures: The Geneva protocols for digital dentures. J Prosthet Dent 2020 Jan;123(1):27–37. doi: 10.1016/j.prosdent.2018.12.008. Epub 2019 May 10. 14. Mavroskoufis F, Ritchie GM. Variation in size and form between left and right maxillary central incisor teeth. J Prosthet Dent 1980 Mar;43(3):254–7. doi: 10.1016/0022-3913(80)90398-4. 15. Lombardi RE. The principles of visual perception and their clinical application to denture esthetics. J Prosthet Dent 1973 Apr;29(4):358–82. doi: 10.1016/s0022-3913(73)80013-7. 16. Jameson WS. Dynesthetic and dentogenic concept revisited. J Esthet Restor Dent 2002;14(3):139–48. doi: 10.1111/j.17088240.2002.tb00514.x. 17. Radlanski RJ, Renz H, Hopfenmuller W. Sexual dimorphism in teeth? Clinical relevance. Clin Oral Investig 2012 Apr;16(2):395– 9. doi: 10.1007/s00784-011-0537-8. Epub 2011 Mar 10. 18. Ferreira Jasse F, Vilhena Correa J, Ferreira Santos da Cruz A, et al. Assessment of the ability to relate anterior tooth form and arrangement to gender. J Prosthodont 2012 Jun;21(4):279–82. doi: 10.1111/j.1532-849X.2011.00822.x. Epub 2012 Feb 19. 19. Ray DS, Wiemann AH, Patel PB, et al. Estimation of the rate of tooth wear in permanent incisors: A cross-sectional digital radiographic study. J Oral Rehabil 2015 Jun;42(6):460–6. doi: 10.1111/joor.12288. Epub 2015 Mar 10. 20. Cesario VA, Latta Jr. GH. Relationship between the mesialdistal width of the maxillary central incisor and the interpupillary distance. J Prosthet Dent 1984 Nov;52(5):641–3. doi: 10.1016/00223913(84)90133-1. 21. Abdullah MA. Inner canthal distance and geometric progression as a predictor of maxillary central incisor width. J Prosthet Dent 2002 Jul;88(1):16–20. 22. Radia S, Sherriff M, McDonald F, Naini FB. Relationship between maxillary central incisor proportions and facial proportions. J Prosthet Dent 2016 Jun;115(6):741–8. doi: 10.1016/j.prosdent.2015.10.019. Epub 2016 Jan 13. 23. Liao P, Fan Y, Nathanson D. Evaluation of maxillary anterior teeth width: A systematic review. J Prosthet Dent 2019;122(3):275–81.e7. doi.org/10.1016/j. prosdent.2018.10.015. 24. Mahshid M, Khoshvaghti A, Varshosaz M N, Vallaei N. Evaluation of “golden proportion” in individuals with an esthetic smile. J Esthet Restor Dent 2004;16(3):185–92; discussion 193. doi: 10.1111/j.1708-8240.2004.tb00032.x. 25. Preston JD. The golden proportion revisited. J Esthet Dent 1993;5(6):247–51. doi: 10.1111/j.1708-8240.1993. tb00788.x. 26. Giddon DB, Bibko J, Anderson NK. Second to fourth digit ratio relation to anterior tooth morphology. J Dent Res 2006;85(Spec Iss A): Abstract #0760 (www.dentalresearch.org). 27. Ladda R, Bhandari AJ, Kasat VO, Angadi GS. A new technique to determine vertical dimension of occlusion from anthropometric measurements of the fingers. Indian J Dent Res May–Jun

2013;24(3):316–20. doi: 10.4103/0970-9290.117993. 28. Fink B, Grammer K, Mitteroeker P, Gunz P, Schaefee K, et al. Second to fourth digit ratio and face shape. Proc Biol Sci 2005 Oct 7;272(1576):1995–2001. doi: 10.1098/rspb.2005.3179. 29. Mavroskoufis F, Ritchie GM. The face-form as a guide for the selection of maxillary central incisors. J Prosthet Dent 1980 May;43(5):501–5. doi: 10.1016/0022-3913(80)90319-4. 30. Mehndiratta A, Bembalagi M, Patil R. Evaluating the association of tooth form of maxillary central incisors with face shape using AutoCAD software: A descriptive study. J Prosthodont 2019 Feb;28(2):e469–e472. doi: 10.1111/jopr.12707. Epub 2017 Dec 27. 31. Álvarez-Álvarez L, Orozco-Varo A, Arroyo-Cruz G, JiménezCastellanos E. Width/length ratio in maxillary anterior teeth. Comparative study of esthetic preferences among professionals and laypersons. J Prosthodont 2019 Apr;28(4):416–420. doi: 10.1111/jopr.12642. Epub 2017 May 17. 32. Shyagali TR, Chandralekha B, Bhayya DP, Kumar S, Balasubramanyam G. Are ratings of dentofacial attractiveness influenced by dentofacial midline discrepancies? Aust Orthod J 2008 Nov;24(2):91–5. 33. Latta Jr GH. The midline and its relation to anatomic landmarks in the edentulous patient. J Prosthet Dent 1988 Jun;59(6):681–3. doi: 10.1016/0022-3913(88)90382-4. 34. McCord JF, Firestone HJ, Grant AA. Phonetic determinants of tooth placement in complete dentures. Quintessence Int 1994 May;25(5):341–5. 35. Fisher RD. Personalized restorations vs. plates. J Prosthet Dent 1973;30(4 Pt 2):513–4. 36. Murrell GA. Complete denture esthetics. Dent Clin North Am 1989 Apr;33(2):145–55. 37. Khan F, Abbas M. The mean visible labial length of maxillary and mandibular anterior teeth at rest. J Coll Physicians Surg Pak 2014 Dec;24:(12):931–4. 38. Vig RG, Brundo GC. The kinetics of anterior tooth display. J Prosthet Dent 1978 May;39(5):502–4. doi: 10.1016/s00223913(78)80179-6. 39. Engelmeier RL. Complete denture esthetics. Dent Clin North Am 1996 Jan;40(1):71–84. 40. Nayar S, Bhuminathan S, Bhat WM, Mahadevan R. Relationship between occlusal plane and ala-tragus line in dentate individuals: A clinical pilot study. J Pharm Bioallied Sci 2015 Apr;7(Suppl 1):S95–7. doi: 10.4103/0975-7406.155822. 41. Tikku T, Khanna R, Maurya RP, Ahmad N. Role of buccal corridor in smile esthetics and its correlation with underlying skeletal and dental structures. Indian J Dent Res Mar–Apr 2012;23(2):187–94. doi: 10.4103/0970-9290.100424. 42. Oshagh M, Zarif NH, Bahramnia F. Evaluation of the effect of buccal corridor size on smile attractiveness. Eur J Esthet Dent Winter 2010;5(4):370–80. 43. Pattanaik S, Pattanaik B. Characterization of a denture base using autopolymerized pour-type denture basin resin and acrylic stain. J Prosthodont Res 2013 Apr;57(2):145–6. doi: 10.1016/j. jpor.2012.08.007. Epub 2013 Feb 27. 44. Frush JP, Fisher RD. The dynesthetic interpretation of the dentogenic concept. J Prosthet Dent 1958;8:558–81. doi. org/10.1016/0022-3913(58)90043-X. T HE AU T HOR , Steven J. Sadowsky, DDS, can be reached at ssadowsky@pacific.edu.

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digital prosthodontics C D A J O U R N A L , V O L 4 9 , Nº 6

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The New Age of Prosthodontics Education: Digital Prosthodontics and Simulation Kumar C. Shah, BDS, MS; Brittany A. Kane, DMD; and Pamela A. Lloren, DDS

abstract Background: Dental education is rapidly changing with digital dentistry, particularly in prosthodontics, and augmented reality simulations along with haptic feedback have enhanced this transformation. Results: This article reviews the features of one such device currently being piloted at the University of California, Los Angeles, School of Dentistry. The impact on student training and education is explored. Practical implications: The future of learning in a virtual environment has the potential to transcend geographical boundaries. Keywords: Haptic, simulation, training, augmented reality, education

AUTHORS Kumar C. Shah, BDS, MS, is a professor of clinical dentistry, division of advanced prosthodontics, and the director of the advanced prosthodontics residency program at the University of California, Los Angeles, School of Dentistry. He is a fellow of the American College of Prosthodontics and the Academy of Prosthodontics. Conflict of Interest Disclosure: None reported.

Brittany A. Kane, DMD, is a resident in the advanced prosthodontics residency program at the University of California, Los Angeles, School of Dentistry. Conflict of Interest Disclosure: None reported. Pamela A. Lloren, DDS, is a resident in the advanced prosthodontics residency program at the University of California, Los Angeles, School of Dentistry. Conflict of Interest Disclosure: None reported.

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dvancements in digital prosthodontics have shaped the practice of dentistry. It is no surprise that dental education models have also evolved, as recent technological advancements present promising enhancements to student education. For example, direct intraoral scanning has become more popular as its accuracy continues to improve, and digital impression techniques are being taught at the predoctoral level by more dental schools. Dental educators have the opportunity to highlight digital advancements and ensure student learning is benefited by the incorporation of haptic technology into dental school curriculums. The removable prosthodontics courses at

the University of California, Los Angeles (UCLA), for example, cover fabrication of removable partial dental prosthesis frameworks and complete removable dental prostheses via digital design and manufacturing. In clinical fixed prosthodontics, students can scan preps and mill restorations for their patients. While the advantages of digital dentistry are numerous at the clinical level, at the preclinical level, the scope of haptic technologies’ potential benefit is just beginning to be explored.1,2 Digital dentistry may be incorporated into preclinical training by utilizing computer-aided design (CAD) software and practicing computer-aided manufacturing (CAM) workflows, and also with other technology that can JUNE 2 0 2 1

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FIGURE 1. Student using SIMtoCARE demonstrating appropriate posture with the handpiece and mirror tool.

FIGURE 2 . Instructor and student using SIMtoCARE dental simulator.

simulate dental procedures to improve dexterity and standardize treatment and objectively evaluate performance. Historically, students in their first year of dental education begin practicing their manual dexterity on typodonts. Students then advance from desktop typodonts to mannequin heads that simulate a clinical setting. Typodonts simulate dental arches and are typically students’ introduction to drilling their first “tooth.” Typodonts sit in mannequin heads to teach students about appropriate clinical posture and ergonomics. Typodont teeth can be individually replaced and are even fabricated with artificial caries to teach students the difference between sound tooth structure and clinical tooth decay. While typodonts have been utilized in dental schools for many years, many experienced practitioners agree that these resin teeth are softer and cut differently than real teeth. Virtual and augmented reality technologies have advanced and expanded their applications into the medical and dental arena. Augmented reality combines a real-world environment with computergenerated perceptual information.3 It is no surprise that the dental field has recognized augmented realities’ potential

to improve dental education. Haptic training simulators can be combined with other methods in preclinical dental skills development that may ease the transition into clinic.4 These haptic training simulators may also improve training at the dental student and graduate student levels through patient-based workflows.

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Haptic Training Simulators Applications in Prosthodontics

Based on technology from Fokker Aircraft’s pilot flight tests, haptic training simulators are the next-generation dental training tool.5 It uses the latest technology available to create a realistic training experience that incorporates perception and manipulation of objects using the senses of touch and proprioception. The haptic training simulator creates an experience that mixes reality with virtual reality objects. It integrates an adjustable phantom head for hand and finger rests and a handpiece and mirror that is movable within a viewing field to simulate the bimanual use of these instruments. The handpiece can provide haptic feedback. This allows the trainee to learn tactile sensations as a bur cuts through the tooth in order to associate finger pressure, resistance with the depth cuts and visual

cues of the simulated tooth preparations.1,4 This haptic feedback is specialized to simulate the different sensations of prepping enamel versus dentin.6 Because the trainee views the simulation through a fixed screen, the trainee is forced to practice proper ergonomics and indirect vision as needed (FIGURES 1 and 2 ). Ultimately, this may help to minimize the gap between preclinical training to the clinical setting. Newer-generation haptic training simulators’ patentpending concepts and exercises set them apart from other simulators on the market. In light of new protocols in place in most dental schools due to the COVID-19 pandemic, these simulators’ application in prosthodontics has never been more relevant.

Benefits for Predoctoral Education

From a predoctoral education standpoint, a haptic dental simulator has multiple advantages over typodont-based preclinical learning.7–10 Students typically start with benchtop preparations on a typodont to familiarize themselves with tools and equipment, such as handpieces or matrices, all with direct vision. They then progress to a phantom head mannequin, where those same typodonts are utilized


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FIGURE 3 . Manual dexterity module. The target

material is in white, leeway material in orange and container material in blue.

to improve manual dexterity as well as familiarity with patient positioning, ergonomics and indirect vision. Downsides to the use of a phantom mannequin include: the costs associated with plastic teeth, where each practice session has a fee associated with it; expert evaluation of the procedure often occurs at the end with no evaluation during the procedure; and inhalation risks of the aerosolization of particles. There is also no pathology that is treated in these exercises. When introduced to haptic technology, dental students valued and appreciated the additional educational benefits the Simodont Dental Trainer can offer.8

Benefits Breakdown No Waste

With haptic simulators, there is no waste of typodont teeth. There is no need to waste time replacing teeth in the dental arch or spend money purchasing replacement teeth. Students can simply restart the preparation or exercise by selecting that function on the keypad.

Tactile Sensation of Enamel vs. Dentin vs. Caries

Unlike plastic teeth that do not feel or look like natural tooth structure, the caries preparation module provides tactile sensation that replicates enamel, dentin

FIGURE S 4 . Student performing caries preparation. Caries is stained in blue and the amount removed is recorded in real time (4A ). Depiction of the instructor and student views (4B ). The student feels the resistance

difference in preparing the carious versus noncarious tooth structure.

and caries. This added tactile sensation prepares students for real patient scenarios and gives them a better idea of what to expect before excavating real tooth decay.

Manual Dexterity and Posture

Unlike with typodonts, haptic simulators force students to posture themselves appropriately and use indirect vision.

Track Student Progress

The virtual reality simulator can record the entire exercise and provide evaluation or guidance of the performance during the exercise in order to pinpoint moments that may be corrected or adjusted. The volume of desired and undesired preparation can also be measured to provide immediate feedback to the student.

Modules

The various modules offered by SIMtoCARE are applicable to many levels of training, which include implant surgery among others. The results for all modules can be evaluated and stored for external assessment.

Manual Dexterity

The modules related to manual dexterity (FIGURE 3 ) allow dental

students to improve their basic dexterity and indirect vision by prepping shapes onto blocks. Indirect vision skills can also be practiced using the dental mirror tool. The exercises in this module contain various shapes with target material that needs to be removed. The target is surrounded by a leeway. The target and leeway are placed in a block-shaped container. The target needs to be drilled out accurately and the leeway is a tolerance zone. Touching the leeway with the bur is acceptable but should be avoided as much as possible. The container should not be drilled. The shapes in the exercises are channels, circles and crosses, with a leeway thickness of either 0.4 or 0.2 mm, offering various levels of difficulty. During the exercise, the elapsed time and percentages of material removed are recorded.

Operative Dentistry

Within the operative dentistry module (FIGURE 4 ), students can practice caries preparations.9 The tactile feedback changes as students prepare enamel, dentin and caries. The cases contain various teeth with different types of caries and different levels of difficulty. The first step is to analyze the caries problem and come up with a treatment  JUNE 2 0 2 1

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Problem-Based, Patient-Specific Learning

FIGURE 6 . Implantology module. Slices of a CBCT

scan are visible while preparing osteotomy site to emulate bone density feedback.

step is to analyze how the root canal can be best reached while preserving as much tooth structure as possible. FIGURE 5 . Example of prosthodontic module

exercise. The amount of enamel and dentin is recorded. Numerous handpiece and bur options are available to select.

plan. Subsequently, the treatment plan is executed and caries can be drilled out where applicable.

Fixed Prosthodontics

Within the prosthodontics module (FIGURE 5 ), students can perform exercises related to both fixed and removable prosthodontics. In regard to crown preparations, these haptic simulators allow the user to see the original shape of the tooth as they prep to visualize the amount of reduction they have completed. Students can also prepare fixed partial denture preparations to assess the path of draw as well as other indirect restorations such as inlays or onlays. Removable prosthodontics can also be part of the module, allowing trainees to practice rest seat and guide plane preparations.

Endodontics

The endodontics module allows the trainee to perform access cavities with visualization of the root canals. The cases contain various teeth that require different approaches for creating the access cavity. The first 404 JUNE

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Implantology

This module contains exercises with cases to train for implant placement (FIGURE 6), with various jaw models that require implants in different locations. The first step is to analyze the specific aspects of the location and plan the correct implant size and type. Next, the location and angle of the planned implant is determined then executed by preparing the osteotomy sites. One of the major areas where patient-specific learning is lacking is surgically at the postgraduate level. The simulators allow residents to import patient CBCT files and practice implant placement. Surgical training in an augmented reality environment allows the user to drill into bone with differing quality and feel the difference in haptic force feedback when switching from one drill to the next.11 Importing DICOM files into the software also allows the student to see their progress in different views of the imported CBCT. As real-time navigation is becoming more popular,12 the steep learning curve associated with dynamic implant placement can be flattened with practice using dental simulator technology that provides immediate feedback during augmented reality implant placement.

This module contains exercises based on patient-specific scans. The haptic training simulator has the ability to import intraoral scans or scans of a dental cast of real patients. A digital dental cast is a life-size likeness of some desired form, formed from a scan of a material poured into a matrix or of an impression. Perhaps the most promising application of this technology is the ability to perform an anticipated treatment in a simulation and evaluate performance all prior to direct patient care. For example, prior to any student performing a procedure on an actual patient, they could import the case in the simulator and rehearse the preparation and steps virtually. In aviation, this is often referred to as briefings, an opportunity to rehearse the steps of a procedure you anticipate performing. This application may allow providers to practice treatment, reduce and anticipate errors and improve overall treatment outcome. With the technology available using the simulators, educators may create custom “model” patients with the desired pathology that then allows students to treat the exercise as they would a real patient. Some programs may have questions associated with the patient for the student to answer, reinforcing theoretical knowledge and applying it in a clinical scenario. This allows students to practice and reinforce the critical thinking that is required during dental procedures on real patients. These exercises may get more complex as the students’ experience improves and may be applied to procedures in operative dentistry and fixed and removable prosthodontics. These preoperative patient exercises may be evaluated by an expert to allow


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the trainee to have feedback on their performance prior to direct patient care and the rendering of irreversible changes.13 This is particularly helpful for a student who may practice prepping their first patient’s crown on a virtual model prior to direct patient care or to visualize the necessary amount of tooth reduction needed for a supererupted tooth, a tilted tooth or a tooth in a severely crowded quadrant of the mouth. At the graduate level, residents can practice prepping fullmouth rehabilitations on their patient to help them with time management and prevention of technical errors that they may face in clinical practice.

Self-Assessment

An additional advantage of dental simulation technology is that all recorded data can be reviewed by the student, allowing them to self-assess and identify areas that need improvement. For each exercise within each module, data is collected that calculates the student’s ability to complete the task with accuracy and records the time it takes to complete each exercise. For example, in the operative module, the amount of caries removed is recorded. In the manual dexterity module, the percentage of material removed is recorded as well as the amount of unwanted object removal, providing feedback in real time. Another unique feature of these simulators is that students can export their completed exercises as a standard tessellation file (STL) and import these files into self-assessment software, such as E4D Compare, which can provide quantifiable feedback of a student’s work on the simulators compared to a control. This software could be used by faculty members as a mechanism to evaluate student work objectively and for students to use as a self-assessment tool.

Considerations and Conclusions

The important consideration of simulations are: Do they mimic real-life situations enough so that the training acquired during the exercises are applicable to the clinic setting and not detrimental? ■  Regarding early versus late exposure to dental simulators, one study showed that haptic simulators could be combined with other methods in preclinical dental skills development and that there is no clear evidence that early exposure to haptic feedback improves psychomotor skills in restorative dentistry.7 Time of exposure should be explored in future studies. As digital dentistry continues to advance, dental educators will continue to incorporate new technology into dental training. Ultimately, haptic dental simulators may ease the transition into the clinic for predoctoral dental students and aid in the improvement of clinical skills for graduate level trainees. n ■ 

8. Bakr MM, Massey WL, Alexander H. Can virtual simulators replace traditional preclinical teaching methods: A students’ perspective? Int J Dent Oral Health 2015;2(1):1–6. dx.doi. org/10.16966/2378-7090.149. 9. Murbay S, Neelakantan P, Chang JWW, et al. Evaluation of the introduction of a dental virtual simulator on the performance of undergraduate dental students in the pre-clinical operative dentistry course. Eur J Dent Educ 2020 Feb;24(1):5–16. doi: 10.1111/eje.12453. 10. Bakr MM, Massey WL, Alexander H. Evaluation of Simodont Haptic 3D virtual reality dental training simulator. Int J Dent Clin 2013;5(4):1–6. 11. Phattanapon R, Gajananan K, Haddawy P, et al. Augmented reality haptics system for dental surgical skills training. Proceedings of the 17th ACM Symposium on Virtual Reality Software and Technology (VRST ’10) 2010:97–98. 12. D’haese J, Ackhurst J, Wismeijer D, et al. Current state of the art of computer-guided implant surgery. Periodontol 2000 2017 Feb;73(1):121–133. doi: 10.1111/prd.12175. 13. Suebnukarn S, Phatthanasathiankul N, Sombatweroje S, et al. Process and outcome measures of expert/novice performance on a haptic virtual reality system. J Dent 2009 Sep;37(9):658–65. doi: 10.1016/j.jdent.2009.04.008. Epub 2009 May 4. T HE CORRE S P ON DIN G AU T HOR , Kumar C. Shah, BDS, MS, can be reached at prosthodontist@ucla.edu.

RE FE RE N C E S 1. Roy E, Bakr M, George R. The need for virtual reality simulators in dental education: A review. Saudi Dent J 2017 Apr;29(2):41–47. doi: 10.1016/j.sdentj.2017.02.001. Epub 2017 Mar 6. 2. Gottlieb R, Vervoorn JM, Buchanan J. Simulation in Dentistry and Oral Health. In: Levine AI, DeMaria S, Schwartz AD, Sim AJ, eds. The Comprehensive Textbook of Healthcare Simulation. 2nd ed. New York: Springer; 2013:329–340. 3. Huang TK, Yang CH, Hsieh YH, et al. Augmented reality (AR) and virtual reality (VR) applied in dentistry. Kaohsiung J Med Sci 2018 Apr;34(4):243–248. doi: 10.1016/j. kjms.2018.01.009. 4. Perry S, Bridges SM, Burrow MF. A review of the use of simulation in dental education. Simul Healthc 2015 Feb;10(1):31–7. doi: 10.1097/SIH.0000000000000059. 5. SimtoCare Dente. Simtocare, About Us. Vreeland, the Netherlands. www.simtocare.com. Accessed July 13, 2020. 6. Mirghani I, Mushtaq F, Allsop MJ, et al. Capturing differences in dental training using a virtual reality simulator. Eur J Dent Educ 2018 Feb;22(1):67–71. doi: 10.1111/ eje.12245. Epub 2016 Nov 19. 7. Bakr M, Massey W, Alexander H. Students’ evaluation of a 3D VR haptic device (Simodont). Does early exposure to haptic feedback during preclinical dental education enhance the development of psychomotor skills? Int J Dent Clin 2014;6(2):1–7.  JUNE 2 0 2 1

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RM Matters

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Treating Elderly Patients: Minimize Risk With Informed Consent and Updated Health History TDIC Risk Management Staff

H

ow does your practice navigate unpredictable times? Beyond the challenges of the past year, dentists often face incidents they can’t anticipate or prevent. But they can be prepared and choose how they respond. In the event of an unanticipated work-related injury or illness, it means having a safety net in place. Workers’ compensation insurance isn’t simply the cost of doing business. It’s a source of critical protection and security for practice owners and their dental teams. An accident on the job can happen at any time, even with staff members following best safety practices. Without workers’ compensation coverage, employees can file a lawsuit against the employer or dental practice, and practice owners could find themselves liable for the settlement. Workers’ compensation insurance provides exclusive remedy for injured employees, meaning that under most circumstances, an employer cannot be sued for causing the injury or illness. For an employer, having workers’ compensation coverage is not only a legal requirement in most states, but it also offers peace of mind. The employer’s role is to make sure their workers’ compensation carrier is able to offer the best possible protection if an employee is injured on the job. This includes reporting all work-related injuries — no matter how insignificant the injury or illness may seem — and reporting the incident within the required timeframe.

Reporting every incident

In a case reported to The Dentists Insurance Company’s Risk Management

Advice Line, an employee tripped and fell in the sterilization room. She began experiencing pain in her arm and believed the pain resulted from the side of her body hitting one of the counters during the fall. She immediately notified the dentist about the fall and the pain in her arm. The dentist advised the employee to take some over-the-counter pain reliever since there were no visible cuts or bruises on her arm. The following day, the employee called the office to inform the

dentist that she would not be coming into work that day and that she had made an appointment to see a doctor because the pain in her arm kept her up at night. The dentist then contacted TDIC’s Advice Line to receive guidance on whether he should report the incident, although he did not believe it was a serious injury. He then told the risk management analyst that he thought the employee was being “dramatic” and he didn’t understand “why she was making a big deal” about what he considered to be a minor fall.

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The analyst advised the dentist that it is his responsibility as the employer to provide necessary first aid treatment in the event of a work-related injury and report it to his workers’ compensation carrier, regardless of how insignificant the incident or injury may appear to him. Workers’ compensation laws vary from state to state; however, employers are generally required to provide a workers’ compensation form to an employee within one business day of becoming aware of a work-related injury or illness. Visit the U.S. Department of Labor’s website for workers’ compensation laws specific to your state.

Understanding the reporting process Once an employer is aware of a work-related injury, it is best practice to report it immediately to allow the workers’ compensation carrier to investigate the injury and determine liability. As part of the reporting process, gather the facts of how the employee was injured, which body parts were injured and the types of injuries, such as a strain, puncture or laceration. This information plays a key role in the investigation of the employee’s claim and acceptance for workers’ compensation benefits. The insurance carrier or assigned third-party administrator will use this information, along with objective medical findings, to determine the compensability of a work-related injury. In the event of an employee injury, dentists should contact their workers’ compensation carrier for an approved network of physicians to send the employee for treatment. TDIC advises against employees seeking treatment with their own 408 JUNE

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health care provider for work-related injuries, as this could delay the claims process, the investigation of the claim and any benefits that the employee may be eligible to receive. In many workplace injury cases, the employee may be ordered by the treating doctor to take leave from work; however, in some cases, the treating physician may release the employee back to work with restrictions. If an injured employee is released to return to work on modified duty, it is important that the dentist cooperates with the physician’s orders to help move along the claims process.

Accommodating modified duties

In a TDIC workers’ compensation claim, an employee slipped and fell in a pool of water from a water dispenser. The dentist reported the incident to her workers’ compensation carrier in a timely manner, but claimed that the injuries did not seem severe at the time the incident was reported. The employee went to see a doctor for her injuries and was permitted to return to work with restrictions; however, the dentist was skeptical that the employee was not being truthful about her work restrictions and refused to let her return to work while she was undergoing treatment for her injuries. After two months of treatment, the employee was permitted to return to work without restrictions, but the dentist was still doubtful of the employee’s claim and would not let her return to the dental office. Because of the dentist’s resistance, the employee sought legal representation and reported several additional injuries in the workers’ compensation claim, including mental stress. After extensive litigation, the claim was eventually settled

and $23,000 was paid directly to the employee. In total, the claim cost over $100,000 to resolve. If work restrictions are provided by the treating doctor and can be accommodated, it is best practice to allow an employee to return to modified work while they are healing from a work-related injury. Had the dentist cooperated and allowed the employee to return to work, the claim statistically should have only cost between $15,000 to $20,000 in total to resolve.

Reducing return-to-work risks

To facilitate a smooth returnto-work process, dentists should start by having a written policy in place that clearly states that modified duties will be available to injured employees for the length of time they are unable to carry out their work duties as normal. Any discussions about an injured employee returning to work with restrictions should be documented in writing and stored in the employee’s file. If appropriate and applicable, it may also be helpful to provide the treating physician with a description of the employee’s normal job duties prior to their injury. The physician may be able to review the list and pick several duties that the employee may still be able to perform while on modified duty and tell the employer which duties should have restrictions. While the employee is on modified duty, the employer should continue engaging in open discussions with the employee about their current work restrictions as they change until the employee’s injury has resolved. Modified work duties should never be construed as punishment and should be beneficial to the productivity of the dental office and employee.


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Every workers’ compensation claim varies, but with each claim, it is imperative that dentists report the injury to their insurance carrier as soon as possible, maintain contact with their carrier to better understand their role as an employer and facilitate open discussions with the employee to ensure a smooth claims process. To better understand the regulations and handle the processes of a workrelated injury: ■  Become familiar with employerrequired postings and employee notifications, as employers are required to ensure their employees are aware of workers’ compensation and the benefits it may provide. ■  Notify the insurance carrier or thirdparty administrator within 24 hours of finding out about the work-related injury so a claim can be set up immediately. ■  Provide the state-required forms to the employee after first notice of injury. ■  Contact the insurance carrier to determine where to send the injured employee for their first medical visit and subsequent care. In the event the employee needs immediate medical care, call 911 or send the employee to the nearest emergency room. ■  Do not treat employees who file workers’ compensation claims or those returning to work after an injury or claim differently than other employees. This will eliminate the potential for an allegation of discrimination based upon filing a workers’ compensation claim. ■  Engage in an interactive discussion with the employee to determine temporary work restrictions and provide transitional work or modified

duty while the employee heals from the injury. Document all discussions in writing, as the notes could be used as part of the claim process and determination of benefits. Mishandling a work-related injury claim could lead to severe consequences, including state penalties, personal liability and loss of exclusive remedy. Practice owners who are unsure about their employer obligations should consult their insurance carrier to ensure they are following workers’ compensation laws. n

The Dentists Insurance Company’s Risk Management Advice Line is a benefit available at no cost to CDA members, as well as to policyholders protected by TDIC. To schedule a consultation, visit tdicinsurance.com/ RMconsult or call 800.733.0633.

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Regulatory Compliance

C D A J O U R N A L , V O L 4 9 , Nº 6

Regulatory Compliance Tips for New Dentists CDA Practice Support

O

nce a dental license is obtained, a new dentist should complete at least one more step before starting work, complete other steps soon after starting work and be aware of certain regulatory compliance matters of interest to new dentists.

Obtain National Provider Identification Number

Every licensed dentist should have an individual (Type 1) NPI number. The Type 1 number is used to identify a prescriber on prescriptions and also the treating provider on treatment claim submissions. A new dentist need not obtain a Type 2 NPI number until they form a business entity, such as a sole proprietorship or dental corporation, which will bill third-party payers for treatment. A dentist may have several Type 2 NPI numbers in the course of their professional career but only one Type 1 number. Apply for an NPI number through the National Plan and Provider Enumeration System at nppes.cms.hhs.gov.

Register Places of Practice

A licensed dentist is required to register their place or places of practice. If they have no place of practice, they should register with the Dental Board of California within 30 days of obtaining their license. A dentist also must notify the board within 30 days of starting at a new place of practice or leaving a practice. Written notification of place of practice must be done on the board-approved form “DDS Change

of Address” found on dbc.ca.gov or through the state at breeze.ca.gov.

Register With DEA and CURES

A dentist who prescribes, administers or dispenses controlled substances must register with the U.S. Drug Enforcement Agency at deadiversion.usdoj.gov. Separate registration in California is not required. The DEA registration is location specific. Additional DEA registration is required if a dentist stores and dispenses or administers controlled substances at more than one facility or practice. If a dentist only prescribes controlled substances at another facility or other dental practices, then only one DEA registration is necessary. Every prescriber with a DEA registration must register to access the Controlled Substance Utilization Review and Evaluation System (CURES), California’s prescription drug monitoring database, at oag.ca.gov/cures. Access credentials must be updated regularly, and the Department of Justice audits for appropriate use of the database. A prescriber is required to check CURES for a patient’s controlled substances prescription history before prescribing a Schedule II–IV drug. More information on CURES is available at cda.org/ practicesupport in the resource titled “Prescribing and Dispensing.” If a dentist does not prescribe, administer or dispense controlled substances, registration with the DEA or CURES is not required. However, know that some dental benefit plans require a dentist to have a DEA registration as part of the credentialing process. A dentist who intends not to prescribe controlled

substances should contact the plans with which they are contracted to confirm the plans’ requirements on DEA registration. A dentist who does not have a DEA registration must still pay the CURES fee that is included as part of the biennial dental license renewal fee.

Prescriptions

In 2021, both paper and electronic prescriptions are accepted at pharmacies. Starting Jan. 1, 2022, all prescriptions must be submitted electronically with few exceptions. A new dentist may be required to register to use an employer’s prescribing software or can choose to subscribe to prescribing software that can be used at more than one location. Find more information on prescription forms and e-prescribing in “Prescribing and Dispensing” at cda.org/practicesupport.

Comply With Practice Name and Ownership Requirements

A practice owner should know that the name of a dental practice or dental corporation may only utilize the name of the licensed dentist owner or owners, unless the owner or owners obtain a fictitious name permit from the dental board at dbc.ca.gov. A dental practice may be owned only by a licensed dentist or dentists. Majority ownership of a dental corporation must be a licensed dentist or dentists except in one limited circumstance. Shareholders in a dental corporation may include nondentists in limited circumstances. Legal counsel should be consulted when considering nondentist ownership in a dental corporation.  JUNE 2 0 2 1

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Understand C.E. Rules for Postgrad, First License Renewal

Continuing education units earned toward license renewal must be delivered by continuing education providers registered by the Dental Board of California, American Dental Association CERP providers or Academy of General Dentistry PACE providers. The board will consider granting continuing education credit for courses offered by nonapproved, out-of-state providers if the dentist submits an application before license renewal. Continuing education units also may be earned through completed curriculum in the license renewal period in a residency program or postdoctoral specialty program approved by the board or the ADA Commission on Dental Accreditation. If audited, a dentist must be able to provide school transcripts to the board. A dentist renewing their license for the first time is exempt from the continuing education requirement. For additional information on C.E. requirements, see the board website at dbc.ca.gov.

Understand Scope of Practice and Supervision

Primary care clinics or clinics owned or operated by a hospital or nonprofit corporation may employ dental professionals but these entities may not interfere with, or otherwise direct, the professional judgment of a dentist or licensed dental auxiliary acting within their scope of practice. The supervising licensed dentist is responsible for determining the competency of the dental assistant to perform basic supportive dental procedures. 412 JUNE

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Understand Rules on Access to Patient Information

Unless the employment agreement prohibits it, a dentist who is a former associate in a dental practice may notify the patients they treated of a new practice location. The former associate dentist may not continue to use the contact information to solicit the patients or to otherwise use patient health information from that dental practice without first obtaining written authorization from the patient. When purchasing a dental practice, the new owner should obtain patient authorization to release records to the new owner. See “Uses and Disclosures of Patient Health Information” at cda.org/practicesupport for additional information on the rules. n Regulatory Compliance appears monthly and features resources about laws that impact dental practices. Visit cda.org/ practicesupport for more than 600 practice support resources, including practice management, employment practices, dental benefit plans and regulatory compliance.


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Supplies | Equipment | Practice Management Systems | Digital Technology | Technical Service | Practice Services revealclearaligners.com May not be combined with any other scanner pricing discounts or other Reveal Clear Aligner discounts. Used or refurbished scanners are not eligible for the program (new units only). © 2021 Ortho Organizers, Inc. All rights reserved. M2142 Certain other restrictions and additional terms and conditions apply. Contact your Henry Schein Dental representative for more details. Must invoice by 12/31/2021. Three cases must be redeemed no later than 6 months after the IOS invoice date. Participating in a promotional discount program (e.g., points, discount redemptions or other special awards) is only permissible in accordance with discount program rules. By participation in such program, you agree that, to your knowledge, your practice complies with the program requirements. Note: This promotion offers a bundled discount. You must fully and accurately report any discounts, rebates or other price reductions (“Discounts”) to Medicare, Medicaid, Tricare and any other federal or State program upon request by any such program. You must claim the benefit of these discounts in the fiscal year in which the discounts are earned, or the following year. Accordingly, you should retain any documentation, including your invoice or purchase order, of Discounts. It is your responsibility to review any agreements or other documents applicable to these prices to determine if they are subject to any Discounts.


Tech Trends

C D A J O U R N A L , V O L 4 9 , Nº 6

A look into the latest dental and general technology on the market

Insta360 Pro 2 Spherical 8K Camera ($4,999, Insta360)

The real estate sector has long made use of 360-degree photography in virtual home tours. With a few clicks, clients can step into a home and dissect every feature on their own time. While taking a 360 photograph is within the capability of most mobile devices, many of these photographs suffer from significant distortions and cropping, ultimately becoming novelties lacking any usefulness. Specialized cameras overcome these shortcomings to varying degrees, and at its nearly $5,000 price point, the Insta360 Pro 2 aims to eliminate these issues. Released in late 2018, the Insta360 Pro 2 employs six super wideangle lenses, gyroscopes and sophisticated on-board electronics to simplify, optimize and maximize 360 image quality for both stills and videos. The device boasts Wi-Fi connectivity so that it can be controlled by a mobile device. Many modern camera conveniences — ISO, log profiles, 12-stop exposure range — are also present. While an 8K resolution sounds impressive, it is the industry standard for high-quality 360 images. Thanks to its on-board systems, the Insta360 Pro 2 can output fully realized, functional 360 files without the aid of further processing: Double clicking on any of these files will place a user into the space where the image was created. It is not the easiest 360 camera to use due its complex interface, multitude of settings and frustrating sensitive power button that turns on the device with little input. Ultimately, even with the significant price tag, seams where the image is stitched together can be seen. Though $5,000 is expensive for a 360 camera, a dental practice may find some utility in it when creating tours for prospective patients and participating in conference calls where multiple individuals in a single location (like people around a conference table) need to be shown. — Alexander Lee, DMD

Microsoft Lists (Begins at $5 per month, Microsoft) Productivity in a team environment is dependent on access to accurate real-time information at any moment. Team members would typically share a spreadsheet to collaborate on via email, but the data is rarely updated continuously with new items from an entry source. Microsoft Lists is a mobile app for environments that utilize Microsoft SharePoint and Teams for the input and reporting of data from consolidated sources to provide useful information for decisionmaking within workgroups. Microsoft Lists requires an account with a Microsoft business or enterprise subscription plan, which includes SharePoint and Teams —­collaborative tools in the Microsoft 365 suite. At the core of these services are lists, which are essentially libraries that can house rows and columns of data. Each column in a list can be customized to accept virtually any type of data, including text, numbers, dates, currency and more. Forms are used to enter a list item or row with data in the appropriate columns. Other methods to add list items containing data include the use of more sophisticated tools such as Microsoft PowerApps or Power Automate. Microsoft Lists provides a basic method to view and interact with any lists that the user has access or permissions to from their mobile device. Users can either search for the name of any list they have access to or pick from recent or favorited lists. When a list is accessed, its rows and columns of data can be viewed based on the role permissions assigned to the user. Adding a list item or editing an existing one can be done directly within the app through a default form. The app can display custom column formatting and list views, but is unable to display PowerApps forms to add, edit or view list items. Overall, this app provides only the basic functionality needed to view and interact with shared data in real time. Other Microsoft browser tools and mobile apps are needed for a more refined experience. Workgroups are dependent on accurate and reliable information to maintain productivity. Microsoft Lists allows team members to easily collaborate, on a simple level, using the same real-time data sources on their mobile devices. — Hubert Chan, DDS

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