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Adhesion: Past, Present, and Future


George Freedman


Initially-misdiagnosed traumatic displacement of primary maxillary canine into the oral vestibule

María José González-Olmo, Bendición DelgadoRamos, Ana Ruiz-Guillén, Martín Romero-Maroto, María Carrillo-Díaz


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Dental News


Adhesion: Restorative Dentistry George Freedman DDS, DiplABAD, FIADFE, FAACD, FASDA Adjunct Professor, Western University of Dental Medicine, Pomona CA

Past, Present, and Future Bonding agents were tentatively introduced in the early 1970s. Since then, the evolution of adhesive techniques has transformed the scope of dental practice. Arguably, the high impact of bonded, appearance-transforming dental restoratives has propelled the dental profession into its greatest prominence in history. In fact, most direct and indirect restorations are adhered to natural tooth structure rather than cemented or mechanically retained. For more than 30 years, highly competitive research and aggressive product development have improved adhesives, initiating, and then fueling, patient demands for conservatively improved oral appearance. The widespread demand and universal use of dental adhesives has largely been a function of two factors: composite restorations are more esthetic than their precursors, and the adhesive margin is more clinically predictable than a non-

bonded interface. The rapid and intensive development of better and easier dental adhesives has focused on simplifying the clinical procedure; decades ago, resin practitioners were faced with a veritable chemistry set of materials to mix and match, in very specific sequences, in order to develop a suitable micromechanical bond between the tooth and the restoration. Adhesion, as defined by most current materials, is micromechanical attachment, not chemical bonding, to enamel and dentin. Dentists were inundated by successive “generations” of adhesive materials in relatively rapid succession. While there is no scientific basis for the term “generation” in dental adhesives, and the classification is to some extent arbitrary, it has served a very useful purpose in the organization of hundreds of commercially available products into a small number of more comprehensible and readily manageable categories.

Generational designations assist in classifying the specific adhesive chemistries involved. They are also very useful in predicting the strengths of the dentinal bond and the ease of clinical use. Generational classification benefits both dentist and patient by simplifying the clinician’s chairside tasks and workflow. The last disruptive advance in adhesive generations (7th generation iBond) was introduced in 2002. Since then, many competitive and innovative bonding agents have been developed, ranging from 4th to 7th generation. The vast majority of these adhesives


Dental News

June 2021

Restorative Dentistry

perform well, and can be used confidently, regardless of their generation; the only major trend is that higher generations offer fewer components, fewer steps, and better chairside predictability. (Fig. 1) In order to best envisage the future of dental adhesives, it is essential to briefly outline their past evolution and their current state.

Adhesion: Past, Present, and Future

resin is greater than the force adhering the material to the enamel, dentin, or both. As the polymerization force causes the resin to contract toward the center of the composite, it pulls the restorative material away from the walls of the cavity, creating a small gap, (Fig. 2) which then allows micro-infiltration of bacteria and plaque that eventually cause marginal breakdown. If the bonding agent’s adhesive strength to dentin and enamel exceed the 17 MPa of polymerization contraction, the shrinkage of the composite is toward the walls of the cavity, (Fig. 3) and no marginal gaps develop, making marginal infiltration of bacteria and oral fluids far less likely, preventing redecay and eventual breakdown.

Figure 2: Less than 17 MPa adhesion: polymerization forces cause resin to contract towards composite center pulling restorative material away from cavity walls. (Courtesy Dr Ray Bertolotti.)

Figure 1: Bonding agents evolve to fewer components, fewer steps, and better chairside predictability.

Bond strength parameters Bonding interface strength is a critical consideration in selecting an adhesive. Some of the basic parameters are conclusively established and well accepted. Munksgaard in 1985 and Retief in 1994 found that 17 MPa was the minimum required for successful adhesion to tooth structure. This figure represents the composite resin polymerization contraction force. If adhesion to either enamel or dentin is less than 17 MPa, the polymerization force of the composite


Dental News

Figure 3: More than 17 MPa adhesion: polymerization contraction causes shrinkage of composite towards cavity walls. (Courtesy Dr Ray Bertolotti.) June 2021

Restorative Dentistry

Adhesion: Past, Present, and Future

Generations 1, 2 and 3 In the late 1970s, dentistry was just beginning to look at adhesive. In fact, there were serious debates as to whether adhesives actually improved longevity. The 1st generation adhesives were rather unsuccessful. Their bond strength to enamel was high (generally, all adhesive generations bond well to the microcrystalline structure of enamel); unfortunately, their dentinal adhesion was virtually non-existent, typically less than 2 MPa. In dental adhesion, it is the bond strength to the semi-organic dentin that is, by far, the greater concern. (Fig. 4) “Bonding”, such as it was, was achieved through chelation to the calcium component of the dentin. Some tubular penetration did occur, but not enough to contribute to retention. Debonding at the dentinal interface was quite common within several months of placement.1

Figure 4: Generations 1, 2 and 3. Low bond strength to dentin.

1st generation bonding agents were recommended for small, retentive Class III and Class V cavities.2 When these bonding agents were used for posterior occlusal restorations, post-operative sensitivity was common.3

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The 2nd generation adhesives were introduced in the early 1980s. The concept at that time was to use the smear layer, which adhered to the underlying dentin at a negligible 2-3 MPa, as a bonding substrate.4 The weak 2-8 MPa dentinal bonding strength of 2nd generation adhesives still required mechanical retention. Restorations with dentinal margins had extensive microleakage, and posterior occlusal restorations exhibited significant postoperative sensitivity. One-year retention rates were as low as 70%, making the longterm stability of 2nd generation adhesives problematic.5,6 Revolutionary 2-component primary/ adhesive systems were introduced in the late 1980s. An innovative application process and significant clinical adhesive improvement (dentin bonding strength of 8-15 MPa), warranted their classification as 3rd generation adhesives. These advances


Dental News

June 2021

diminished the need for cavity retention form. It is noteworthy that erosion, abrasion, and abfraction lesions were treatable with minimal tooth preparation, heralding the dawn of ultraconservative dentistry. With posterior occlusal restorations, there was a noticeable decrease in post-operative sensitivity; this signaled the practical launch of esthetic, direct posterior restorations. These adhesives were the first generation that bonded not only to tooth structure, but (weakly) to dental metals and ceramics as well. However, the issue of longevity was still major problem: intraoral adhesive retention with 3rd generation bonding agents decreased significantly after three years. Interestingly, while patients reported significant levels of posterior post-operative sensitivity, their increasing demands for tooth-colored restorations pushed many dentists to begin providing routine posterior composite fillings.7,8,9

had a bond strength to dentin (17-25 MPa) that overcame the polymerization shrinkage that had bedeviled adhesive dentistry previously. For the first time, dentists had a predictable adhesive that could compete in longevity to traditional techniques, and most jumped at the opportunity. Esthetic and cosmetic dentistry can date their growth and continuing popularity to the adhesives from the 4th to 7th generations. (Fig. 5) Post-operative sensitivity for posterior teeth was still an issue (at 30%+), but it was finally manageable enough that it encouraged many dentists to switch from amalgam to direct posterior composite fillings. 4th generation adhesion is characterized by hybridization at the dentin-composite interface. Hybridization involves resin replacing hydroxyapatite and water in the surface dentin. The resin and the remaining collagen fibers constitute the hybrid layer. Hybridization occurs in both the dentinal tubules and the intratubular dentin, dramatically improving bond strength to dentin. 13-16 Total etching and moist dentin bonding, concepts developed by Fusayama and Nakabayashi in Japan in the 1980s, introduced to North America and popularized by Gwinnett and Bertolotti are the innovative hallmarks of the 4th generation adhesives.17,18

Figure 6: Components of 4th generation adhesives.

Figure 5: Generations 4, 5, 6 and 7. Acceptable to excellent bond strength to dentin.

4th Generation: predictable adhesion the tipping point The early 1990s transformed dentistry, and predictable adhesion was largely responsible. 4th generation agents

The products in this generation have 3 or more components. (Fig. 6) One is the etch (typically 37% orthophosphoric acid). The other two or more ingredients must be mixed and applied, in very precise ratios and sequences; this is easy at the bench, but rather more complicated chairside. The number of precise ratios and mixing steps tend to confuse the process, increasing the likelihood of technique sensitivity, thereby reducing actual bonding strength.

Restorative Dentistry

Adhesion: Past, Present, and Future

5th Generation: more predictable, 2 components These adhesives are characterized by the absence of a separate etch component. (Fig. 8) There are typically 2 (sometimes more) components that must be mixed prior to use or applied in a specific sequence; either protocol can cause some confusion.

Figure 7: Components of 5th generation adhesives.

Within 5 years, in the mid 1990s, the highly popular 5th generation dental adhesives were introduced. Their major advance was that they had only 2 components: the etch and a pre-mixed adhesive. (Fig. 7) Etching is still required but there is no mixing, and thus, less possibility for error. The bond strength to dentin is 20-25+ MPa; not as high as the 4th generation, but not as variable either. These adhesives are indicated for all dental procedures (except self-curing resin cements and composites). They adhere well to enamel, dentin, ceramics and metal, and post-operative sensitivity is significantly reduced. Dental procedures tend to be both stressful and technique sensitive. 5th generation bonding agents are very easy to use and predictable, reducing the strain on dentist, staff and patient. The adhesive is applied directly onto the prepared tooth surface and polymerized.

6th Generation: no separate etching step

Figure 8: Components of 6th generation adhesives.

7th Generation: 1 component, 1 step An innovative, simplified adhesive system, the 7th generation, was introduced in 2002. Just as the 5th generation bonding agents made the leap from earlier multi-component systems to a rational and easy-to-use single bottle (plus etch), 7th generation simplified 6th generation materials into a single component, single bottle system. (Fig. 9) No-mix 7th generation adhesives self-etch and selfprime and self-bond to streamline procedures with no technique sensitivity and no post-operative sensitivity; they represent the most advanced formulation of dentinal adhesives available.

There were extensive efforts to eliminate the separate etching step, culminating in the introduction of 6th generation adhesives in 2000. These bonding agents have a dentin-conditioning (surface etching) liquid incorporated into one of their components. The acid treatment of the dentin is self-limiting, and the etch byproducts are permanently incorporated into the dentalrestorative interface. No rinsing is required. There is virtually no post-operative sensitivity. Some of the early 6th generation adhesives bonded well to dentin, but the unetched, unprepared enamel bond interface was prone to early failure. These issues have been addressed with the current 6th generation products that are on the market.


Dental News

Figure 9: Single component of 7th generation adhesives. June 2021

Eliminating mixing uncertainty eliminates technique sensitivity. No etching step is required. The priming and bonding of tooth surfaces are accomplished simultaneously, significantly simplifying the adhesive procedure. 7th generation adhesives are predictable one-step, onebottle systems for the complete etching and bonding of all enamel and dentin surfaces with no rinsing. Excellent dentin bonding (18-35 MPa) and similar micromechanical adhesion strength to both prepared and unprepared enamel allow effective use for direct and indirect composite.

Some manufacturers have claimed to introduce 8th generation adhesives, but on closer inspection, they turn out to be earlier generation adhesives reconfigured for marketing purposes. By consulting the Adhesive Classification Table (Fig. 10), it is easy to assign every existing adhesive to one of the 4 generations from 4th to 7th. Given the trends described above, it can be readily seen that each “generation” has simplified the adhesion process significantly: fewer components, fewer steps, less chairside time, easier use, and better predictability.

“Moist” bonding is not required! 7th generation adhesives are insensitive to the amount of residual moisture (not contaminating saliva) or dryness on the surface of the preparation. The acid-base reaction of the 7th generation creates its own moisture at the restorative interface. The bond strength to both dentin and enamel are essentially the same, regardless of the moisture or lack of moisture on the prepared surfaces.

8th Generation: what does it look like? There has been no quantum leap advance in adhesion technology in more than 17 years! The simple reason is that adhesives are so predictable and effective that there has been little incentive to support research and development. The existing adhesives are well-known, universally accepted, and represent a very sizable market worldwide.

Figure 11: What is the 8th generation adhesive?

How can a single-component, single-step, total-comfort process be improved upon? The answer is as simple as it is difficult to develop: zero-step adhesives. (Fig. 11)

Figure 10: Adhesive Classification Table – determine the classification of any adhesive.

The only possible evolution is to eliminate the remaining component and single step entirely. The 8th generation adhesive will have no bottle and no components, at

Restorative Dentistry

least as a distinct, separate, clinical step. The adhesive will be incorporated into the restorative material. As the practitioner inserts the restorative composite resin, the contained adhesive will etch, prime, and bond both the dentin and enamel surfaces, requiring only polymerization to finalize the restoration.

Adhesion: Past, Present, and Future

7. Christensen GJ. Bonding ceramic or metal crowns with resin cement. Clin Res Associatees Newsletter 1992;16:1-2. 8. O’Keefe K, Powers JM. Light-cured resin cements for cementation of esthetic restorations. J Esthet Dent 1990;2:129-131. 9. Barkmeier WW, Latta MA. Bond strength of Dicor using adhesive

Far-fetched? These chemistries are already available to the dental profession: self-etching, self-priming, and self-bonding 1-step resin cements and post-andcore composites. The next major evolution of dental adhesives, the 8th generation, will see the elimination of this treatment process as a separate step. The only task that remains is to incorporate these 8th generation adhesives into direct restorative materials. It is only a matter of time….

systems and resin cement. J Dent Res 1991;70:525. Abstract. 10. Holtan JR, Nyatrom GP, Renasch SE, Phelps RA, Douglas WH. Microleakage of five dentinal adhesives. Op Dent 1993;19:189-193. 11. Fortin D, PerdigaoJ, Swift EJ. Microleakage of three new dentin adhesives. An J Dent 1994;7:217-219. 12. Linden JJ, Swift EJ. Microleakage of two dentin adhesives. Am J Dent 1994;7:31-34.


13. Barkmeier WW, Erickson RL. Shear bond strength of composite to enamel and dentin using Scotchbond multi-purpose. Am J Dent 1994;7:175-179.

1. Harris RK, Phillips RW, Swartz ML. An evaluation of two resin sys-

14. Bouvier D, Duprez JP, Nguyen D. Lissac M. An in vitro study of

tems for restoration of abraded areas. J Prosthet Dent 1974;31:537-

two adhesive systems: third and fourth generations. Dent Mater



2. Albers HF. Dentin-resin bonding. Adept Report 1990;1:33-34.

15. Gwinnett AJ. Shear bond strength, microleakage and gap formation with fourth generation dentin bonding agents. Am J Dent

3. Munksgaard EC, Asmussen E. Dentin-polymer bond promoted by


Gluma and various resins. J Dent Res 1985;64:1409-1411. 16. Swift EJ, Triolo PT. Bond strengths of Scotchbond multi-purpose 4. Causlon BE, Improved bonding of composite resin to dentin. Br

to moist dentin and enamel. Am J Dent 1992;5:318-320.

Dent J 1984;156:93. 17. Gwinnett AJ. Moist versus dry dentin; its effect on shear bond 5. Joynt RB, Davis, EL Weiczkowski G, Yu XY. Dentin bonding agents

strength. Am J Dent 1992;5:127129.

and the smear layer. Oper Dent 1991;16:186-191. 18. Pashley DH. The effects of acid etching on the pulpodentin com6. Lambrechts P, Braem M, Vanherle G. Evaluation of clinical perfor-

plex. Oper Dent 1992;17:229242.

mance for posterior composite resins and dentin adhesives. Oper Dent 1987;12:53-78.


Dental News

June 2021

Oral Surgery

Initially-misdiagnosed traumatic displacement of primary maxillary canine into the oral vestibule Abstract

Latifa Hammouda

Eya Moussaoui

Ines Kallel

The coincidence of both soft tissue injury and traumatic tooth avulsion requires special consideration because of the possible projection of the tooth or its fragments into the soft tissue. If it is undetected at the time of the emergency treatment, such fragments can lead to severe complications.

Here, we report a case of an initially-misdiagnosed embedded primary maxillary canine in the lower oral vestibule following traumatic tooth avulsion. This location is not frequent and only one case was reported in the literature. Diagnosis was based on the clinical and radiographic examinations. The tooth was successfully removed without any complication.

Lamia Walha

Introduction Nabiha Douki Head of the Odontology department at the university hospital of Sahloul, Sousse, Tunisia

Dental trauma is common in children and adolescents, and it is caused by different factors, including falls, sports, school accidents, vehicle accidents, etc. 1. Among these injuries, avulsion is often discussed in dental traumatology because of the various subsequent complications. The problem arises especially when the involved teeth are not found, as these teeth could be projected into the oral soft tissues. In addition, psychological and functional damage could also arise. A tooth or its fragment may displace anteriorly, posteriorly, or vertically depending on the direction and the energy of the trauma. Also, the displacement of a tooth or its fragments into soft tissue usually involves the central and lateral incisor; but the canines are rarely involved 2. In most cases, the embedded tooth or its fragments are found in the lips 3,4,5, the tongue 6, and the nasal cavity 2,7; but they are rarely found in the oral vestibule 8. This case report presents the particularity characterizing the displacement of maxillary primary canine into the vestibule of the mouth, emphasizes the necessity to examine and explore all soft tissue wounds when missing teeth are present, and highlights the value of conventional intraoral radiographs in the detection of embedded teeth.


Dental News

June 2021

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Oral Surgery

Initially-misdiagnosed traumatic displacement of primary maxillary canine into the oral vestibule

Case report A 12-year-old boy was referred to the Department of Dentistry and Oral Surgery at Sahloul University Hospital by the emergency unit following a dentofacial trauma. His parents reported a fall associated with loss of consciousness 48 hours before their attendance. The patient had no general antecedents. A CT-scan performed at the emergency unit revealed the avulsion of teeth 11, 21, 22, and 23 accompanied by a subcutaneous oblique embedded tooth opposite to the symphysis region. The tooth was not specified. No examination was performed for the missing teeth, the embedded tooth, or the oral soft tissue wounds and no treatment was provided. Only sutures were performed for the chin skin wound. Antibiotic (Augmentin) and steroidal anti-inflammatory drugs (Unidex) had been prescribed. Then, the patient was referred to our department for the replacement of the avulsed teeth, which were not found by the parents. Extraoral examination showed a lower lip laceration and facial abrasions, which were initially treated at the emergency unit using primary suture with black silk wound dressing (fig. 1).

The intraoral view also revealed a lower lip edematous and a lacerated wound covered by fibrous tissues and which was painful during palpation (fig. 2.a). Moreover, a lacerated open wound was noted in the oral vestibular mucosa opposite to the mandibular anterior region, accompanied by pus discharge (fig. 2.b).

A B Figure 2: Intraoral view of: a) A lacerated and edematous wound in the lower lip covered by fibrous tissues. b) A lacerated open wound in the oral vestibular mucosa accompanied by pus discharge.

Figure 1: View showing a plaster covering the chin abrasions extra-orally with four uninhabited alveoli of the 11, 21, 22, and 23 intra-orally.

A thorough intraoral examination revealed uninhabited alveoli of the 11, 21, 22, and 23, with an incomplete eruption of the 12 and the presence of the 53 on the dental arcade (fig. 1). Examination of the 11, 21, and 22 alveoli with a curette and saline cleaning showed the presence of blood clots without any dental fragment, with the exception of the canine alveolus, where permanent canine germ was detected.


Dental News

Figure 3: Intra-oral radiograph, with a gutta-percha cone placed in the lower oral vestibular wound, showing the embedded primary maxillary canine into the vestibule opposite to the lower anterior teeth. June 2021

Oral Surgery

Initially-misdiagnosed traumatic displacement of primary maxillary canine into the oral vestibule

Cold and percussion tests, as well as periodontal probing were normal for all the mandibular anterior teeth. The CT-scan confirmed the expulsion of the 11, 21, and 22, and showed the presence of the 13 and 23 germs with a root development exceeding half of the total root length (fig. 4). A subcutaneous embedded canine was also noted in the mandibular anterior region with oblique direction. A radiograph of the soft tissues, performed by placing a peri-apical film in the lower labial sulcus, did not reveal a radio-opaque image near the wound site.

The incision was sutured with 4.0 silk suture threads. A favorable healing of the wound was noted and the sutures were removed on the tenth postoperative day. After complete gingival healing, a temporary dental prosthesis was made to replace the three permanent avulsed teeth. This prosthesis would not serve as a space maintainer for the 23, since the latter achieved half of its total root length.

An intra-oral radiograph, carried out with a gutta-percha cone placed in the lower oral vestibule wound, showed the presence of an embedded missing canine, just opposite to the lower anterior teeth (fig. 3).

Figure 5: Intra-oral view during surgery showing the exposure of the embedded canine into the soft tissue of the oral vestibule.

Figure 4: Three-dimensional (a), sagittal (b), and coronal (c) CT images of the oral cavity revealing traumatic avulsion of the 11, 21, 22, and 23 associated with subcutaneous oblique embedding of the left maxillary primary canine opposite to the mandibular symphysis and showing the presence of the 13 and 23 germs.

Based on the patient’s history and on the clinical and radiographic findings, diagnosis of embedded left maxillary primary canine in the lower oral vestibule following avulsion trauma was made. The patient’s parents were informed about the presence of a primary canine in the lower vestibular mucosa and that this tooth could not be replanted. The wound site and the surrounding tissues were cleansed with a betadine detergent. Under local anesthesia, a horizontal incision was made in the lacerated vestibular mucosa, and the embedded canine was surgically removed (fig. 5, fig. 6).


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Figure 6: Identified and removed temporary canine with root resorption.

Discussion Avulsion corresponds to a total displacement of the tooth out of its alveolar bone. It is accompanied by the rupture of the vascular-nervous bundle and the periodontal ligament fibers 9,10. Prevalence of tooth avulsion varies from 0.5% to 3% 11, and from 6% and up to 16% 12 depending on studies. Maxillary central incisors are the most affected 13, probably because of an increased over-jet (greater than 6 mm) and an June 2021

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Oral pathology

Oral Surgery Initially-misdiagnosed traumatic displacement of primary maxillary canine into the oral vestibule

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inadequate labial protection with a short upper lip 14,20. This is in line with our case involving anterior maxillary teeth avulsion. When dental injuries are accompanied by surrounding soft tissue laceration, during the first consultation, the clinician should be attentive to a possible entrapment of a tooth or a tooth fragment into these wounds 3. Cases involving displacement of a tooth or a tooth fragment into various soft tissues have been reported in the lower lip, which is the most common site, followed by the upper lip 3, 4, 5, tongue 6, 15, 16, and nasal cavity 2, 7. However, they are extremely rare in the oral vestibule. An extensive review of the literature reports only one case of traumatic displacement of a maxillary permanent canine into the upper vestibule of the mouth 8. Herein, we report a second case of a maxillary primary canine embedded in the lower oral vestibule following maxillary anterior teeth avulsion.

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A case of a tooth fragment embedded in the lower lip and that remained undiagnosed for 3 years was reported by Carson Mader. A firm, painless, and 1 cm mass in the lower lip, with a fractured crown of the maxillary left central incisor was the reason for the patient’s consultation 20.

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If they are undetected during the first consultation, such tooth fragments and foreign bodies may remain undiagnosed for longer periods. Long-term sequelae of an embedded tooth or tooth fragment include persistent chronic infection, pus discharge, formation of fibrous scar tissue leading to delayed healing, vascular and nervous sheath damages, spontaneous eruption or migration of the fragment in an unpredictable direction, in addition to medico-legal constraints 17, 18, 19.

This is the only report in the literature documenting the duration of a tooth embedded in the lip for this period of time. In 2010, Al-Jundi also reported a case of a 13-yearold child with a fractured tooth fragment embedded in the lower lip that remained overlooked for eighteen months 21. The patient consulted for esthetic restoration of his upper left incisor and he did not complain of any pain or discomfort. There are also published cases of spontaneous eruption of undetected tooth fragments from the soft tissues, due to continuous movement and contraction of the muscles. However, this desired evolution remains


Dental News

June 2021

exceptional. In 2006, Rao and Hegd reported a case of a spontaneous eruption, after eight months, of a tooth fragment impacted in the lower lip following trauma to the maxillary central incisor 22. This finding shows the importance of an adequate cleansing of the oral mucosa wound prior to suturing during acute and subacute management of orofacial injuries. The usual recommendation is to detect and remove the embedded tooth to prevent immediate or delayed complications 3, 23. In most of the times, failure in detecting an embedded tooth or a tooth fragment, and unsatisfactory emergency management by the medical practitioner may be related to the complexity and the nature of the dental injuries, as well as to unawareness of the importance of oral soft tissue examination 21, 24. Adequate collaboration between the involved medical and dental practitioners has a considerable value.

Radiographs are also essential tools to establish differential diagnosis between dental expulsion, full dental intrusion, or embedded tooth. The choice of radiographs should be individualized to the unique needs of each case. It should therefore be based on the outcome of the detailed history-taking and the clinical examination, as well as the delivered radiation dose 25, 26. In managing traumatic dental injuries, intra-oral radiographs with three different angulations, horizontal angle (90°) with central beam through the involved tooth, lateral view from the mesial and distal aspects of the involved tooth 27, are usually sufficient to assess most of the dento-alveolar injuries. They must therefore be used during the initial evaluation and follow-up visits. For trauma in the anterior region, one occlusal film and three periapical exposures, using different angulations, are recommended 25.

The present case indicates that intraoral examination, especially soft tissue inspection, during the acute step of oro-facial trauma management was not performed at the emergency department, thus leading to failure in detecting and removing the embedded tooth before consulting our dental department. In fact, clinically, a tooth embedded in the soft tissue may not be easily detected because of the lacerated and bleeding lesion. It can also be hidden by the contraction of orbicularis oris muscles 3.

They are important to identify the type, localization and extent of the injuries 25, and to eliminate the possibility of other diagnoses.

Diagnosis is mainly dependent on the history of the trauma, and the clinical and radiographic examinations of both hard and soft tissues. A detailed history of the accident is important to determine the etiologic mechanism, the impact energy, the direction of the causal agent in order to suspect secondary fracture localization, the extra-oral dry time, and the missing teeth 19.

Soft tissue lacerations, with a possible embedded tooth or a foreign body, can be successfully evaluated using intra-oral radiographs with a very short exposure time 25.

In this case, the patient consulted two days later with a soft tissue edema, laceration, and pus discharge after the wound debridement. It was so difficult to palpate the lacerated soft tissue accurately because of the painful and edematous wounds in the lower lip, covered by the fibrous tissue, and the pus discharge from the lacerated lower vestibular mucosa. So, a plain soft tissue radiograph should be performed, using a low radiation dose 25 to help detect and localize the embedded tooth in the oral soft tissues.

Recently, digital intra-oral radiographic systems are becoming increasingly used and are replacing traditional dental X-ray films for the diagnosis of dental diseases. In cases of traumatized teeth, no significant differences between the two techniques are detected, but the lower radiation in digital radiography favors this modality 25.

Extra-oral radiographs are indicated in isolated cases of dental trauma. Panoramic radiography provides a global and non-detailed image of teeth. In cases of oro-facial trauma, it is usually indicated where a temporomandibular joint problem is detected or a jaw fracture is suspected 28, which is not the case in our report. Three-dimensional imaging (both CT-scan and CBCT), despite delivering a higher radiation dose, has a great potential to help in the diagnosis and treatment planning of dental trauma associated with maxillofacial injuries 25,29. In fact, it allows better visualization of the traumatized dento-alveolar structures by eliminating superimpositions of the adjacent anatomic structures 27.

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Initially-misdiagnosed traumatic displacement of primary maxillary canine into the oral vestibule

In the present case, the CT-scan, performed during the emergency consultation, confirmed the diagnosis of expulsion and revealed the subcutaneous oblique embedding of the left maxillary primary canine opposite to the mandibular symphysis. However, it did not specify the point of entry of this tooth because of the presence of two lacerated mucosa wounds in the mandibular symphysis, in the lower lip, and even in the lower oral vestibule. Intra-oral radiographs were therefore required.

4. A. A. Antunes, T. S. Santos, A. U. Carvalho De Melo, C. F. Ribeiro, S. R. J. Goncalves, and S. De Mello Rode, “Tooth embedded in lower lip following dentoalveolar trauma: case report and literature review,” General Dentistry, vol. 60, no. 6, pp. 544–547, 2012. 5. AGRAFIOTI, Anastasia, TSATSOULIS, Ioannis N., PAPANAKOU-TZANETAKI, Styliani I., et al. Primary inadequate management of dental trauma. Journal of Clinical and Diagnostic Research: JCDR, 2016, vol. 10, no 7, p. ZD12. 6. DE SANTANA SANTOS, Thiago, MELO, Auremir Rocha, PINHEIRO, Rober-

In the emergency consultation, the medical practitioners focused on eliminating any vital complication and on detecting any other bone localized fracture. No attention was paid to the tooth embedded in the oral soft tissues.

to Tiago Alves, et al. Tooth embedded in tongue following firearm trauma: report of two cases. Dental traumatology, 2011, vol. 27, no 4, p. 309-313. 7. A. H. B. Luna, R.W. F. Moreira, and M. de Moraes, “Traumatic intrusion of maxillary permanent incisors into the nasal cavity: report of a case,” Dental

Avulsion of permanent teeth is the most serious of all dental injuries. Prognosis depends on the measures taken at the accident site and the extra-oral time after avulsion 28.

Traumatology, vol. 24, no. 2, pp. 244–247, 2008. 8. IWASE, Masayasu, ITO, Michiko, KATAYAMA, Hanon, et al. Traumatic displacement of maxillary permanent canine into the vestibule of the mouth. Case reports in dentistry, 2015, vol. 2015.

In our case, complete removal of the canine was performed, but replantation could not be carried out. In fact, this act should not be performed when primary teeth are avulsed because of the risk to the underlying permanent tooth germ 28.

9. RAO, Dinesh et HEGDE, Sapna. Spontaneous eruption of an occult incisor fragment from the lip after eight months: Report of a case. Journal of Clinical Pediatric Dentistry, 2006, vol. 30, no 3, p. 195-197. 10. Naulin-Ifi C, Machtou P. Traumatismes dentaires : du diagnostic au trait-

A literature search has not revealed any case with replantation of a tooth embedded in the oral soft tissue. However, some cases involving reattachment procedures of embedded tooth fragments have been reported, with a good long-term follow-up 30, 31, 32.

ement. Rueil-Malmaison, France : Editions CdP, impr. 2005 ; 2005. ix+165 p. 11. DE ANDRADE VERAS, Samuel Rodrigo, BEM, Jessica Silva Peixoto, DE ALMEIDA, Elvia Christina Barros, et al. Dental splints: types and time of immobilization post tooth avulsion. Journal of Istanbul University Faculty of Dentistry, 2017, vol. 51, no 3 Suppl 1, p. S69. 12. Andreasen JO, Andreasen FM, Andersson L. Textbook and color atlas of traumatic injuries to the teeth, 4th edn. 2007. p. 217–54, 444–88, 516–41.


13. Hecova H, Tzigkounakis V, Merglova V, Netolicky J. A retrospective study of 889 injured permanent teeth. Dental Traumatology 2010; 26:466-75. 14. Pektas ZO, Kircelli BH, Uslu H. Displacement of tooth fragments to the

1. O’Neil DW, Clark MV, Lowe JW, Harrington MS. Oral trauma in children: a

lower lip: A report of a case presenting an immediate diagnostic approach.

hospital survey. Oral Surg Oral Med Oral Pathol 1989; 68:691–6.

Dent Traumatol 2007; 23:376-9.

2. B. R. Chrcanovic, S. C. Bueno, D. T. da Silveira, and A. L.N. Cust´odio, “Trau-

15. Andersson L, Andreasen JO, Day P, Heithersay G, Trope M, Diangelis AJ et

matic displacement of maxillary permanent incisor into the nasal cavity, «Oral

al. International Association of Dental Traumatology guidelines for the man-

and Maxillofacial Surgery, vol.14, no. 3, pp. 175–182, 2010.

agement of traumatic dental injuries. 2.Avulsion of permanent teeth. Dental Traumatology 2012; 28: 88-96.

3. A. C. da Silva, M. DeMoraes, E. G. Bastos, R.W. F. Moreira, and L. A. Passeri,


“Tooth fragment embedded in the lower lip after dental trauma: case reports,”

16. F. J. Hill and J. F. Picton, “Fractured incisor fragment in the tongue: a case

Dental Traumatology, vol. 21, no.2, pp. 115–120, 2005.

report,” Pediatric Dentistry, vol. 3, no. 4, pp. 337–338, 1981.

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June 2021


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The VistaPano S Ceph is the efficient X-ray solution for jaw orthopaedics and more. It supplies fast Ceph shots (4.1 seconds) with outstanding image quality and low exposure to radiation. At the same time, thanks to S-Pan technology, its 2-D panorama shots provide excellent definition. More at

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Initially-misdiagnosed traumatic displacement of primary maxillary canine into the oral vestibule

17. D. G. McDonnell and E. X. McKiernan, “Broken tooth fragments embedded in the tongue: a

22. Al-Jundi SH. The importance of soft tissue examination

case report,” British Journal of Oral and Maxillofacial Surgery, vol. 24, no. 6, pp. 464–466,1986.

in traumatic dental injuries: a case report

18. Dent Traumatol 2010; 26:509-11. McDonnell DG, McKiernan EX. Broken tooth fragments em-

23. NAGAVENI, N. B. et UMASHANKARA, K. V. Tooth frag-

bedded in the tongue: A case report. British J of Oral Maxillofacial Surg 24: 464–466, 1986.

ment embedded in the lower lip for 10 months following dentoalveolar trauma: A case report with literature review.

19. T.-C. Tung, Y.-R. Chen, C.-T. Chen, and C.-J. Lin, “Full intrusion of a tooth after facial trauma,

Burns & trauma, 2014, vol. 2, no 3, p. 2321-3868.135652.

«The Journal of Trauma, vol. 43, no. 2, pp. 357–359, 1997. 24. Agarwal A, Rehani U, Rana V, Gambhir N. Tooth frag20. SALAMA, Fouad S. et ABDELMEGID, Faika Y. MISSED DIAGNOSIS OF TOOTH FRAGMENTS

ment embedded in the upper lip after dental trauma: A case


report presenting an immediate diagnostic approach and complete rehabilitation. J Indian Soc PedodPrev Dent 2013;

21. MADER, Carson. Restoration of a fractured anterior tooth. Journal of the American Dental


Association (1939), 1978, vol. 96, no 1, p. 113-115. 25. Marwaha M, Bansal K, Srivastava A, Maheshwari N. Surgical Retrieval of Tooth Fragment from Lower Lip and Reattachment after 6 Months of Trauma. Int J Clin Pediatr Dent 2015; 8:145-8. 26. KULLMAN, Leif et AL SANE, Mona. Guidelines for dental radiography immediately after a dento-alveolar trauma, a systematic literature review. Dental traumatology, 2012, vol. 28, no 3, p. 193-199. 27. Kim IH, Mupparapu M. Dental radiographic guidelines: a review. Quintessence Int 2009; 40:389–98. 28. FLORES, Marie Therese, ANDERSSON, Lars, ANDREASEN, Jens Ove, et al. Guidelines for the management of traumatic dental injuries. II. Avulsion of permanent teeth. Dental traumatology, 2007, vol. 23, no 3, p. 130-136. 29. Andreasen JO, Andreasen FM, Andersson L. Textbook and color atlas of traumatic injuries to the teeth, 4th edn. Oxford: Blackwell Munksgaard; 2007. 30. Greondahl G, Huumonen S. Radiographic manifestations of periapical inflammatory lesions. How new radiological techniques may improve endodontic diagnosis and treatment planning. Endod Topics 2004; 8:55–67.

Light-curing Glass Ionomer Filling Material • Excellent working time and the setting time is individually adjustable by light-curing • Immediately packable after placement in the cavity • No varnish required- fill, polymerise and finish • No need to condition the dental hard tissue • Does not stick to the instrument and is easy to model • Suitable for large cavities

31. Lauritano D, Petruzzi M, Sacco G, Campus G, Carinci F, Milillo L. Dental fragment embedded in the lower lip after facial trauma: Brief review literature and report of a case. Dent Res J (Isfahan) 2012;9 (Suppl 2): S237-41. 32. Pasini S, Bardellini E, Keller E, Conti G, Flocchini P, MajoranaA. Surgical removal and immediate reattachment of coronal fragment embedded in lip. Dent Traumatol 2006; 22:165-8.

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Introduction to lean dentistry Why management?

Sami Bahri, DDS

Two events, among countless others, made me realize that learning business management could help not only businesses or individuals, but entire populations. The first event was in preparation for World War II (WWII), when the united states congress created a training program called Training Within Industry (TWI). In a record time, TWI transformed a variety of manufacturing plants into war manufacturing plants and helped win the war. The second event happened at the end of WWII, when Japan was devastated by two atomic bombs. “To revive its collapsed economy, Japan focused on process management.

Improved quality, combined with lower cost, created new international demand for Japanese products, which led to huge economic growth for Japan during the 1960s.”1 This focus on process management, generated a new management system pioneered by Toyota—The Toyota Production System (TPS) on which lean management is based. Today, more than 80 years after its inception, Lean management is still the latest phase in our collective knowledge on business management. It has proven more successful than previous management theories at Toyota, in companies worldwide, and lately in healthcare in general and dentistry.

What is Lean Dentistry Main goal The ideal condition for lean dentistry is to be totally responsive to patients’ needs by treating them when they want, in the amount they want, without interruption between providers. But how to be this responsive when patient demand is so unpredictable? the answer is flexible business systems through two factors: short treatment lead times that allow to receive patients on a short notice and flexible job descriptions that allow staff members to work wherever needed to accommodate changing demand. When asked about the secret for Toyota’s success, Taiichi Ohno, the Toyota executive widely credited as the chief architect of the TPS, the model for lean management, defined lead time and gave it credit for Toyota’s success: “All we are doing is looking at the time line from the moment the customer gives us an order to the point when we collect the cash, and we are reducing that time line by removing the non-value-added wastes.”2.


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June 2021




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In fact, while experimenting with management practices, “Toyota made a critical discovery: when you make lead times short and focus on keeping production lines flexible, you actually achieve higher quality, better customer responsiveness, better productivity, and better utilization of equipment and space. this discovery became the foundation for Toyota’s success globally in the twenty-first century.”3

Lead Time in Dentistry In dentistry, lead time is measured from the moment patients call for an appointment to the moment their need is fulfilled. That lead time needs to be constantly shortened by removing waste—activities that do not help in advancing treatment. 4

Introduction to lean dentistry

Technical guidelines In making things, we know two techniques: batching, adopted by classical management, and one-piece flow, adopted by lean management. (Figure 1). To varying degrees, processes are usually a mix of the two techniques. Consider the theoretical case of three patients, each needing three crowns. Batching would consist of making one crown at a time on each patient, for a total of nine appointments. Onepiece flow, which is the ideal lean process, would treat three crowns, on one patient at a time, for a total of 3 longer appointments: a savings of six appointments.

Examples of those wasteful activities have been classified as what became known as the seven wastes: Transportation of materials or patients to different parts of the office, inventory accumulation (our main inventory is invisible: treatments planned but unfinished), excessive motion of workers, waiting (anyone waiting for anything), overprocessing, overproduction –performing an activity too soon, too late, in excessive quantity, and defects passed on the next staff member or to patients.

Adjust the process design to eradicate waste When we observe any of the seven wastes, we need to eradicate it. But beware! attacking waste directly is not effective. Because, just as pain is a symptom of underlying disease, the seven wastes are symptoms of underlying weaknesses in the design of your work systems.

Figure 1: Lean adopts One-Piece Flow not Baching. If you list all the support functions needed for each appointment, you will find that one-piece flow has saved a large number of steps, thus, a large amount of unnecessary effort that you can convert into productive efforts (Figure 2).

For example, when patients are in pain, you do not just prescribe analgesics, you treat the root cause of that pain. Similarly, if you see the waste of patients waiting, you cannot simply ask them to stop waiting, you must treat the root cause of the wait and adjust the design of your systems by following some established technical and social guidelines.

Technical and social guidelines to adjust the process design The following technical guidelines—the mechanics of lean management, and social guidelines—how to lead people and keep them motivated, have developed over the last eighty years.


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Figure 2: In one year we have saved 1796 appointments (25% of the total number of yearly appointments) multiplied by the number of associated supporting steps. June 2021


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Introduction to lean dentistry

Note that for a practitioner who sees batching as the normal way of practicing dentistry, making six additional appointments— collecting six additional times, setting up and cleaning the rooms six additional times, etc.—would seem like normal and necessary work. In contrast, a lean practitioner would call them hidden waste disguised in the form of necessary work. The premise of lean management is to constantly look for that kind of hidden waste and remove it.

To show the advantages of loading around the average, you can consider a practice that sees 10 patients one day and 190 the next day. Its average is 100 patients per day, but it must be equipped for receiving the maximum number of 190 patients. Now, if for every 10 patients you need one employee, this practice will need 19 employees. If that same practice sees 100 patients a day (the average), that same practice will need 10 employees instead of 19, to produce the same amount of dentistry. (figure 2).

Technical requirements

Leveling the schedule is a simple calculation that distributes work evenly across the schedule. In our case, with that simple calculation we have saved 40% of the number of people required to handle the schedule and redirected them to grow the practice.

To understand the technical requirements of lean management one needs to understand its two types of goals. The first type is called True-North goals; those cannot be reached all the time, but they set a direction for improvement efforts. The second type is Intermediate goals; reachable goals along the direction set by True-North goals. (Figure 3)

3. Quick changeover As we have seen, one-piece flow is the ideal state of a lean dental process. It means to perform crowns, root canals, fillings, surgery, removable prosthetics, etc. in the same appointment, and move between these procedures very quickly. We will need to change our instruments quickly, and to turn the rooms over to the next patient quickly. Quick changeover is a science that has been introduced by a Toyota consultant, Shigeo Shingo5, who was able to reduce the changeover time of a large press from 4 hours to less than 10 minutes. We studied his principles and were able to change between procedures or change the rooms between patients very efficiently.

Figure 3: True-North goals give direction; Intermediate goals ensure progress. There are four technical, fundamental principles to creating a lean management system. Those principles are also true-north goals that cannot be reached at a 100 percent, but trying to reach them will allow for sizeable improvements: 1. One-piece flow One-piece flow is the ideal in lean dentistry. It means to treat, in as few visits as possible, as much as the patient condition allows, with no delays between providers, no rework, and no work left to be done after the visit is finished. 2. Level the schedule Leveling is a simple way of managing the workload with the right number of resources—employees, space, time, or finances. It divides the workload into small parts, equal to the average load needed by every working time unit and distributed evenly over the available time.


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4. Synchronization Synchronization means that the different procedures and the different providers need to work together like an orchestra or like a ballet. Providers come in time to perform their part of the treatment on their common patient without making that patient wait and without making the assistant or the hygienist wait either. In practice, synchronization can be very complex because many providers are working on many patients and they all have unpredictable conditions. That is why we found the need to create a new position called “Patient Care Flow Manager” whose job is to orchestrate the movement of providers and patients with the goal of directing providers where they are needed, at the time they are needed. The flow manager’s goal is to provide uninterrupted treatment to every patient. To communicate efficiently with providers, the flow manager uses a “Kanban” (a Japanese word meaning signal), containing June 2021

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all the information needed to allow them to go to the next patient just-in-time for treatment (figure 5)

Introduction to lean dentistry

ing, and motivating teams, are crucial to the success of a lean program. When it comes to motivation, a manager’s interests conflict with those of a leader. The goal of a manager to preserve processes stable and predictable; while a leader wants to improve them and take the company to ever higher levels. This dilemma becomes even bigger when you are both, the manager, and the leader. To combine both duties, you will need a system for preserving the standards but also for improving them. Toyota, the model company for lean management, has found a way to satisfy a leader and a manager at the same time. I can summarize it as follows:

Figure 4: Working around the average load is called Leveling. It requires fewer resources to handle the schedule.

Social Guidelines All the technical guidelines mentioned above are unusable unless employees are willing to execute them. That is why engag-

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Preserving and Improving Standards The main weapon in a manager’s arsenal is standard work; it describes how a procedure must be done in that practice. In classical management practices, standard work is established by management; employees must follow it.


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In lean practices, we discuss the standard work with the team until we come up with a consensus on how things should be done to simplify work for everyone. Although agreed upon by the whole lean team, the standard is nothing but a starting point for improvement. As they try it, most of the time people find it to work partially; let’s say in 70% of the cases. Then, the team discusses a solution for the remaining 30%. When they try the new solution, they usually find that instead of solving the 30% of the cases, it solves 10%, for example. They go back to discuss the remaining 20% etc. They keep repeating the cycle until they are satisfied that 100% of the cases are covered. That is what continuous improvement (CI) looks like.

How to achieve continuous improvement As you can see from the previous section, continuously improving the standard requires full participation from team members. That is why it is very critical for a leader/manager to know how to keep them motivated, and willing to share their experience with the established standard. To that end, Fujio Cho, a former president of Toyota Motor Company has given valuable advice (figure 4) Go See Direct observation is more effective than reading reports. One way is to treat any problem like a crime investigation where you do not rely on hearsay. You go to the crime scene and observe any evidence that leads you to the source of the problem. Remember we are trying to find the source of the problem so we can change the design of our process not only treat the symptoms.

Introduction to lean dentistry

Show Respect After practicing a job for a while, your employees get to know the details of their jobs, better than their managers. For that reason, when we look for solutions, we should assume that they know what they are doing and not blame them for the problem. Which leads us to the next section Ask what in the system caused that? Management guru, W. Edwards Deming6 , said that 94% of the problems are caused by the design of the system not by unwilling employees. Consequently, when you find a problem, you must find what in your system has caused that employee to do an imperfect job. So, we ask:” What in the system caused you to make that mistake?” then we go back and fix the system. One of the worst mistakes is to ask people to pay attention. We must assume that when people get tired, they tend to make mistakes. We need the systems and the environment prevent mistakes

Figure 6: Advice for continuous improvement.

Where to Start? Grasping the lean principles requires practice. I suggest you start as small as possible, one dentist, one assistant, one front desk and one hygienist. Try one-piece flow on one simple treatment plan. Observe the obstacles and solve the problems they present. Based on what you learned move to more complex cases and finish them in one appointment. And continue adding more complex cases to the one-piece flow at the pace of your learning. Figure 5: The flow manager uses a Kanban to synchronize provider movements and allow for just-in-time treatment.


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June 2021


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Community Dentistry Introduction to lean dentistry

Conclusion Lean management is the latest in our collective knowledge on business management. It seeks to eradicate all process waste. Seven wasteful activities have been described as symptoms of process waste. However, to remove those wastes, we do not attack them directly, but we go back to the process design and repair in it the part that caused the waste. Our main criterium for a better process design is a shorter treatment lead time, to make the business more flexible and more responsive to the unpredictable variation in patient demand. Shorten lead times and create more flexible systems, we need to cater to the practical aspect of lean management—one-piece flow, leveling, quick changeovers and synchronization. and to the social (human) aspect of lean management—go see, ask why and show respect. All processes must be continually improved by team members who can recognize hidden waste when it happens and know how to eradicate it. This brings us to the most important message in lean management, you must invest in people first, because they are the ones who will help you build and improve systems that will raise you to success and prosperity.



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3. Liker, Jeffrey. The Toyota Way, 14 management principles from the world’s greatest manufacturer, second edition, McGraw Hill, 2021, p.13 4. Bahri, Sami; The lean dentist: Establishing one-piece flow in patient treatment. Lean Enterprise Institute, Inc., June 2016. 5. Shingo, Shigeo; A Revolution in Manufacturing: The SMED System 6. Deming, W. Edwards. The new economics for industry, government, education MIT, Center for advanced engineering study 1993 page 135

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June 2021

Epidemiology of Oral Health

María José González-Olmo 1

Bendición Delgado-Ramos 2

Ana Ruiz-Guillén 1

Martín Romero-Maroto 1

María Carrillo-Díaz 1

1: Dentistry Department, Rey Juan Carlos University, Avda de Atenas s/n, 28922, Alcorcón, Madrid, Spain

2: Dentistry Department, Granada University, Campus de la Cartuja s/n, 18071, Granada, Spain

Republished from

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Oral hygiene habits and possible transmission of COVID-19 among cohabitants Abstract Background To find out whether misuse of dental hygiene, in terms of certain dental habits, may facilitate the spread of COVID-19 among cohabiting individuals. Methods 302 COVID-19 infected (PCR +) subjects cohabiting with someone else at home were selected for an observational crosssectional study. An anonymous online questionnaire was developed using Google forms to avoid person-to-person contact. The structured questionnaire consisted of questions covering several areas: sociodemographic data, cross transmission to another person living together, oral hygiene habits during confinement, care and disinfection control behaviours in the dental environment like sharing toothbrush, sharing toothbrush container, sharing toothpaste, placing brush vertically, placing cap with hole for brush, disinfecting brush with bleach, closing toilet lid before flushing.

Results Tongue brushing was more used in the group where there was no transmission of the disease to other members (p < 0.05). Significant differences were found for shared toothbrush use (p < 0.05), although shared use was a minority in this group (4. 7%), significant differences were also found for the use of the same container (p < 0.01), shared use of toothpaste (p < 0.01), toothbrush disinfection with bleach (p < 0.01), brush change after PCR + (p < 0.05). The women performed significantly more disinfection with toothbrush bleach (p < 0.01), closing the toilet lid (p < 0.05) and changing the brush after PCR + (p < 0.05). Conclusions The use of inappropriate measures in the dental environment could contribute to the indirect transmission of COVID-19 between cohabitants.

Background The new coronavirus (SARS-CoV-2) is causing concern in the medical community, as the virus is spreading globally. The fact that asymptomatic people are potential sources of infection 1 justifies a thorough analysis of the dynamics of the transmission of the current outbreak. The virus is mainly transmitted through direct or indirect contact with the mucous June 2021

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Epidemiology of Oral Health

Oral hygiene habits and possible transmission of COVID-19 among cohabitants

membranes of the eyes, nose or mouth 2, 3. In this context, the detection of SARS-CoV-2 and a high viral load in the sputum of a convalescent patient raises concerns about the potential transmissibility after recovery. The SARS-CoV-2 virus, commonly referred to as a coronavirus because of its unique appearance, has a glycoprotein configuration on its exterior, forming spicules, through which it binds to human cells. In order to protect its genetic contribution, it has a double layer made of lipids in its lower part that performs this protective function 4. The SARS-CoV-2 virus infects human cells using the ACE2 receptors, which are widely distributed in the upper respiratory tract (hence the lung lesions it causes in affected people) and the epithelial cells lining the ducts of the salivary glands, these being early targets of infection 5,6,7. They can also be in the mouth, mainly on the tongue, which is a great reservoir of viral germs. Therefore, tooth brushing, interproximal hygiene and tongue cleaning are essential in order to reduce the viral load in the oral area 3, 8. In addition, in order to prevent cross-contamination, it is important to ensure that tooth brushes within the family are not in the same container. After use, cleaning devices become contaminated and, if not disinfected, can be a reservoir of microorganisms 9 (including bacteria, viruses and fungi) that maintain their viability for a significant amount of time, ranging from 24 h to 7 days. Microbial survival promotes the reintroduction of potential pathogens into the oral cavity or the spread to other individuals when cleaning devices are stored together or shared 10. This has always been a bad idea, but today this separation has become a real necessity, as if we are asymptomatic carriers of the virus without knowledge of it and the brushes are placed together, it can encourage crosscontamination. Recent studies have observed that COVID-19, through friction with the oral mucosa, can be transmitted to the individual 11. The same tube of toothpaste should also not be used between members of the same family, as this is another way of facilitating cross-contamination. It is also necessary to store the toothbrush with the brush head upwards, as this facilitates faster drying and hinders the spread of microorganisms 12,13,14. Even if the brush is accompanied by a wrapper, it must have openings to facilitate drying.


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Toilets should be considered as a possible source of viral contamination of indoor and surface air. In fact, constant microbial contamination of the indoor environment often occurs after toilet flushing, and this can be a major source of spread, not only for enteric but also for respiratory viruses, which are also often eliminated by faecal means. Toilet flushing generates a large number of droplets of different sizes: the larger droplets settle quickly on surrounding surfaces, while the smaller ones can be inhaled or remain in the air for a long time 15. The level of contamination in the toilet environment has been studied, concluding that the highest levels of surface contamination were located near the source of the aerosol, at the level of the toilet seat. However, contaminated surfaces were also found at a distance of 83 cm from the toilet. This is the reason why the toothbrush should also be kept away from the toilet (at least 1 m) to avoid possible contamination, as the virus is also found in feces and urine 16, 17. At the end of an eventual infectious, process it is necessary to be cautious and use a new brush, as even if the power of reinfestation of the virus is not known, it is necessary to bear in mind that the brush can constitute an emitter of germs to other brushes used by other members of the family or even to one’s self. Disinfection of the brush head after use with povidone-iodine at 0.2% or hydrogen peroxide diluted at 1% for 1 min 18 is very necessary to maintain good cleanliness 19, as the brush filaments can be infected by germs from the environment. It is necessary to know and take into account the temporary duration of the stay of the coronavirus on different surfaces 18; in order to prevent infection, it is important to know that the duration for the stay of coronavirus on plastic is 72 h. When there is an active development of COVID-19, a 0.2% povidone-iodine mouthwash or 1% dilution of hydrogen peroxide can be used for 1 min 18 to try to control the oral load of germs, as although scientific evidence is limited 1, 18, it has been observed that such products can be effective in rendering the lipid envelope of the virus inoperative. There are many families who are currently confined to their homes because they are positive for COVID-19. Precautionary measures regarding cleanliness and asepsis to be performed in the homes by family members are well-known in order to prevent infection among them 20 . However, less emphasis has been placed on oral care to reduce the viral load and on the dental environment to prevent the risk of cross-contamination of COVID-19. June 2021

Taking into account the above considerations, the aim of this research is to find out whether misuse of dental hygiene, in terms of certain dental habits, may facilitate the spread of COVID-19 among cohabiting individuals.

Methods Design type This was a cross-sectional, observational study conducted in Spain for fifteen days (April 15–30 2020), four weeks after the start of the confinement in Spain. Data collection These data collection efforts were particularly designed to avoid person-to-person contact. It was an online study, and only participants with Internet access could participate in the study. A snowball sampling technique was used. An anonymous online questionnaire was developed using Google forms with a consent form attached. The link to the questionnaire was sent by email, WhatsApp and other social networks through the researchers. Participants were encouraged to complete the survey with as many people as possible. Therefore, the link was forwarded to people apart from the first point of contact, etc. Included participants were over 18 years old, able to understand Spanish, and willing to give an informed consent. A total of 2305 subjects agreed to the survey, but only those subjects who had a confirmation in PCR (Polymerase Chain Reaction) of a COVID-19 infection and who were living with another person with whom they shared a bathroom were selected, the sample being reduced to 302 subjects included in the analysis. The survey and consent to participate were approved by the King Juan Carlos University Ethics and Research Committee (Registration number: 0103202006520). Instruments The structured questionnaire (included as supplementary file) consisted of questions covering several areas: (1) sociodemographic data (age, gender and educational level), (2) cross transmission to another person living in the same home and sharing a bathroom, with a response format carried out via a dichotomous question (yes = 1/ no = 0), (3) oral hygiene habits during confinement (brushing 2 or more times per day, flossing once per day, mouth rinsing once per day, brushing tongue once per day). Responses were rated on a 5-point Likert scale

ranging from 1 to 5, with “Never” = 1, “Almost never” = 2, “Sometimes” = 3, “Almost always” = 4 and “Always” = 5. Questions also covered (4) care and disinfection control behaviors in the dental environment (Usually sharing a toothbrush, usually sharing a toothbrush container, usually sharing toothpaste, usually placing brush vertically, usually placing cap with hole for brush, usually disinfecting brush with bleach, usually closing toilet lid before flushing, changing toothbrush after COVID-19 + test). The response format was carried out via a dichotomous question (yes/no). Statistical analysis The study presents a cross-sectional descriptive study, in which the variables considered are those described in the previous section. Statistical analysis was performed using the SPSS version 24 (SPSS Inc., Chicago, IL, USA). Data analysis included descriptive statistics and the Kolmogorov–Smirnov test to evaluate the assumption of normality, which was confirmed. In order to know the possible differences between groups with infection from a single family member and those with an extension to more than one household member, T tests were performed in the case of quantitative variables and Chisquare tests in the case of variables. Significance levels were established at 0.05.

Results The sample consisted of 145 (48%) men and 157 (52%) women with an average age of 39.25 (± 9.94). In terms of educational levels for the total sample, 34.1% had completed primary school, 29.8% had completed secondary school and 36.1% had obtained a university degree. 59.6% of the sample corresponds to a medium socio-economic level. 56.3% of the sample had a person living with them affected by COVID-19 and positive in a PCR test. Oral hygiene habits Only 33.8% brushed their teeth 2 or more times every day, 20.2% flossed every day, 15.2% used a daily rinse and 17.2% brushed their tongue every day. We found significant differences in oral hygiene measures for tongue brushing (t = 2.202; p = 0.029*).

Epidemiology of Oral Health

Oral hygiene habits and possible transmission of COVID-19 among cohabitants

This hygiene measure was more used in the group in which there was no transmission of the disease to other members of the home. No significant differences in these measures were found in terms of sex. (Table 1)

Significant differences were found between the group in which there was no intrafamily cross-transmission and in which there was cross-transmission for shared toothbrush use (x 2(1) = 4.006; p = 0.045*).

Care and control of disinfection of the dental environment 97% of the sample did not share the use of the toothbrush, but 64.2% used the same container to hold the toothbrushes, 50.3% used the same toothpaste, 80.5% put the toothbrush upright, 55.6% used a cap for the brush, only 8.6% of the sample dipped the brush in bleach after use, 36. 4% closed the toilet lid before flushing and only 16.2% did not change the brush after testing positive for PCR.

Although shared use was a minority in this group (4.7%), significant differences were also found for the use of the same container (x 21) = 18.550; p = 0.000**), shared use of toothpaste (x 2(1) = 9.720; p = 0.002**), toothbrush disinfection with bleach (x 2(1) = 7.532; p = 0.006**), toilet lid closure (x 2(1) = 23.062; p = 0.000**) and brush change after PCR + (x 2(1) = 4.077; p = 0.043*). (See Table 1)

Table 1: Mean, standard deviation and significance for the variables dental hygiene and disinfection control of dental environment by sex and cross infection group


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June 2021

Discussion When the association between the variables of oral hygiene and care and control of disinfection of the dental environment was explored, significant differences were found between the subjects who performed brushing hygiene with bleach and those who did not with respect to the use of dental floss (p = 0.028*) and tongue hygiene (p = 0.035*). Differences were also found between subjects who lowered the toilet seat and subjects who had tongue hygiene (p = 0.020*). (Table 2) Gender differences for the study variables The differences in these measures in terms of gender were significant for personal hygiene or disinfection measures, such as disinfection with toothbrush bleach (x 2(1) = 7.087; p = 0.008**), closing the toilet lid (x 2(1) = 5.518; p = 0.019*) and changing the brush after PCR + (x 2(1) = 4.090; p = 0.043*). These measures were used more in women than in men with a significant difference.

In this study, we explored the role played by the correct use of anti-contamination measures in the dental environment to prevent infection among people living in the same house. The results have highlighted this association, considering that sharing a toothbrush, toothpaste, the same container for the brush, closing the toilet lid before flushing and changing the brush after the viral process could be a possible route of crosscontamination of COVID-19. However, when studying oral hygiene habits, no significant differences were found between the groups except for tongue cleaning. This result can be interpreted to indicate the tongue as the main oral organ acting as a reservoir of COVID-19 5 and the importance of brushing to decrease the viral load of the individual carrier. The study shows significant differences in the measures taken to avoid cross-contamination with respect to gender, with the figures being higher in women than men.

Table 2 Mean, standard deviation and significance for the variables disinfection control of dental environment and dental hygiene

Epidemiology of Oral Health

Oral hygiene habits and possible transmission of COVID-19 among cohabitants

This finding is consistent with previous results obtained in the literature regarding care and cleaning in the home, in which the leading role of women is emphasized. In addition, men seem to be more affected by COVID-19 than women 7, 20, 21, so it is doubtful whether this could be due to less comprehensive compliance with prevention measures. It is also important to recognize some limitations of this study. First, a more definitive method would have been to measure the aerosol and surface viability of SARSCoV-2 on the different surfaces and toilet environment but it is not possible because of the impossibility to visit each home due to the lockdown situation. Second, it is a matter of convenience. However, the sample size is acceptable to show a first approximation of what could happen if adequate measures are not taken in the dental environment. A possible third limitation comes from the use of self-report measures, which may be affected by responses based on social desirability. Finally, only measures affecting the dental environment have been considered, so the results could be partially biased. This research has some relevant implications for the possible spread of COVID-19. There is evidence that everyday hygiene measures are a vital part of infection prevention and are important in preventing the transmission and acquisition of infection. Adopting a specific hygiene approach in our homes and our daily life (e.g., workplaces, public transport, gyms, nursery schools and shopping centers), in situations in which there is usually no mandatory hygiene policy, offers a way to maximize protection against infections. In order to minimize the risk of viral infection among cohabitants, the population should be informed of the measures in the dental environment that should be taken to reduce possible cross-contamination, including not sharing a toothbrush or the same toothpaste tube, not sharing the cup where the toothbrush is stored, closing the toilet lid before flushing, disinfecting the toothbrush after each use and changing the toothbrush after a viral process.

pressure for the development and further spread of resistance 14. As noted in recent global efforts to contain the SARS-CoV-2 virus and slow the spread of COVID-19, hygiene practices, including hand washing, are the first line of defense to reduce the transmission of infection. It is also important to recognize that while hygiene measures and disinfection of toilets and oral equipment to prevent the spread of COVID-19, appear to be necessary to consider in preventing the spread of COVID-19, it is vitally important to comply with all general measures outlined at the global level in order to contain the spread. Although there is evidence that hygiene in the dental environment is important to prevent transmission of COVID-19 colonization and infection, further research is needed to demonstrate the extent to which poor hygiene in the dental environment may contribute to the burden of infection and cross-contamination of COVID-19. In addition, it would be interesting to know the different effects depending on the number of people in the household.

Conclusion The use of inappropriate measures in the dental environment could contribute to the indirect transmission of COVID-19 between cohabitants.

Availability of data and materials The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

Abbreviations PCR: Polymerase chain reaction

If effectively implemented, hygiene in the home and in daily life has the potential to reduce infection rates and antibiotic consumption, thus reducing the selective


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June 2021

References 1. Abduljalil JM, Abduljalil BM. Epidemiology, genome, and clinical fea-

12. Medrano-Félix A, Martínez C, Castro-Del Campo N, León-Félix J,

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4. Guarner J. Three emerging coronaviruses in two decades. Am J Clin

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5. Liu L, Wei Q, Alvarez X, Wang H, Du Y, Zhu H, et al. Epithelial cells lining

15. Verani M, Bigazzi R, Carducci A. Viral contamination of aerosol and

salivary gland ducts are early target cells of severe acute respiratory syn-

surfaces through toilet use in health care and other settings. Am J Infect

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Control. 2014;42:758–62.

caques. J Virol. 2011;85:4025–30. 16. Barker J, Jones MV. The potential spread of infection caused by aerosol 6. Peng X, Xu X, Li Y, Cheng L, Zhou X, Ren B. Transmission routes of

contamination of surfaces after flushing a domestic toilet. J Appl Micro-

2019-nCoV and controls in dental practice. Int J Oral Sci. 2020;12:9.

biol. 2005;99:339–47. 17. Zhang J, Wang S, Xue Y. Fecal specimen diagnosis 2019 novel coro7. Chen N, Zhou M, Dong X, Qu J, Gong F, Han Y, et al. Epidemiological

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monia in Wuhan, China: a descriptive study. Lancet. 2020;395:507–13. 18. Kampf G, Todt D, Pfaender S, Steinmann E. Persistence of coronavi-

ruses on inanimate surfaces and their inactivation with biocidal agents. J 8. Wang WK, Chen SY, Liu IJ, Chen YC, Chen HL, Yang CF, et al. Detec-

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different time intervals and effectiveness of various disinfecting solutions in reducing the contamination of toothbrush. J Indian Soc Pedod

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Prev Dent. 2002;20:81–5.

on conventional and antibacterial toothbrushes. Biofilms. 2004;1:123–30. 20. Chan JF, Yuan S, Kok KH, To KKW, Chu H, Yang J, et al. A familial

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infection Yi













Digital Dentistry Thomas T. Nguyen,

Use of Artificial Intelligence in Dentistry: Current Clinical Trends and Research Advances Abstract

DMD, MSc, FRCD(C) Assistant Professor, Faculty of Dentistry, McGill University, Montreal, Quebec Naomie Larrivée, BASc MSc, 4th year dental student *

Alicia Lee, BASc MSc, 4th year dental student *

Olexa Bilaniuk, BASc MSc, Research Software Developer, Mila – Quebec AI Institute, Montreal, Quebec.

Robert Durand, DMD, MSc, FRCD(C) Associate Professor *

* Faculty of Dental Medicine, Université de Montréal, Montreal, Quebec

Republished from the Journal of the Canadian Dental Association

All Rights Reserved


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The field of artificial intelligence (AI) has experienced spectacular development and growth over the past two decades. With recent progress in digitized data acquisition, machine learning and computing infrastructure, AI applications are expanding into areas that were previously thought to be reserved for human experts. When applied to medicine and dentistry, AI has tremendous potential to improve patient care and revolutionize the health care field. In dentistry, AI is being investigated for a variety of purposes, specifically identification of normal and abnormal structures, diagnosis of diseases and prediction of treatment outcomes. This review describes some current and future applications of AI in dentistry.

for a variety of purposes in dentistry: identification of normal and abnormal structures, diagnosis of diseases and prediction of treatment outcomes. Furthermore, AI is used extensively in dental laboratories and is playing a growing role in dental education. The following review describes current and future applications of AI in the clinical practice of dentistry.

What once seemed like science fiction is now becoming reality in health care. Artificial intelligence (AI) is a fast-moving technology that enables machines to perform tasks previously exclusive to humans.1 Advances in AI offer a glimpse of such health care benefits as decreasing postoperative complications, increasing quality of life, improving decision-making and decreasing the number of unnecessary procedures.2

Historically, artificially intelligent systems applied hand-crafted rules to the specific tasks they were meant to solve. Each task required domain-specific knowledge, engineering and manual fine-tuning of the system by subject-matter experts. For instance, a system designed to detect lesions in medical imaging might look for abnormally coloured lumps of a given shape. The fine-tunable parts of the system might be a range of healthy tissue colours or minimum lengths and widths for a potential lump. Nowadays, medicine most commonly uses a branch of AI called machine learning5 and, more recently, deep learning.6

When applied and dentistry, in improving revolutionizing

to the fields of medicine AI can play a crucial role diagnosis accuracy and care. AI is currently used

What Is Artificial Intelligence? AI is a branch of computer science that aims to understand and build intelligent entities, often instantiated as software programs.3 It can be defined as a sequence of operations designed to perform a specific task.4

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Use of Artificial Intelligence in Dentistry: Current Clinical Trends and Research Advances

Machine learning (ML) is a branch of AI in which systems learn to perform intelligent tasks without a priori knowledge or hand-crafted rules. Instead, the systems identify patterns in examples from a large dataset, without human assistance. This is accomplished by defining an objective and optimizing the system’s tunable functions to reach it. In this process, known as training, an ML algorithm gains experience through exposure to random examples and gradual adjustments of the “tunables” toward the correct answer. As a result, the algorithm identifies patterns that it can then apply to new images. This technique is analogous to an adult showing several photos of cats to a child. The child eventually learns the patterns involved in recognizing a cat and identifying one in new images. Deep learning (DL) is a sub-branch of ML wherein systems attempt to learn, not only a pattern, but also a hierarchy of composable patterns that build on each other. The combination and stacking of patterns create a “deep” system far more powerful than a plain, “shallow” one. For instance, a child does not recognize a cat in a single, indivisible step of pattern-matching; rather, the child first sees the edges of the object, a particular grouping of which defines a textured outline with simple shapes, such as eyes and ears. Among these components, larger groups such as heads and legs arise, and a particular grouping of these defines the whole cat. An extremely popular class of DL algorithms is the artificial neural network (ANN), a structure composed of many small communicating units called neurons organized in layers. A neural network is composed of an input layer, an output layer and hidden layers in between.7 It is possible to have 1 or a few hidden layers (shallow neural network) or multiple/many hidden layers (deep neural network, DNN) (Figure 1, a and b). These layers are called hidden because their values are not prespecified or visible to the outside. Their aim is to make it possible to build hierarchically on information retrieved from the visible input layer to compute the correct value of the visible output layer. The pattern of connections between neurons defines the particular neural network’s architecture, and the fine-tunable strengths of those connections are called the weights of the neural network. In medicine and dentistry, one of the most commonly used subclasses of ANN is the convolutional neural network (CNN) (Figure 1c). A CNN uses a special neuron connection architecture and the mathematical operation,


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convolution, to process digital signals such as sound, image and video. CNNs use a sliding window to scan a small neighbourhood of inputs at a time, from left to right and top to bottom, to analyze a wider image or signal. They are extremely well adapted to the task of image classification and are the most-used algorithm for image recognition.7

Clinical Application of AI in Dentistry Radiology CNNs have shown promising ability to detect and identify anatomical structures. For example, some have been trained to identify and label teeth from periapical radiographs. CNNs have demonstrated a precision rate of 95.8–99.45% in detecting and identifying teeth, almost rivaling the work of clinical experts, whose precision rate was 99.98%.8,9 CNNs have also been used for the detection and diagnosis of dental caries.10 In 3000 periapical radiographs of posterior teeth, a deep CNN algorithm was able to detect carious lesions with an accuracy of 75.5–93.3% and a sensitivity of 74.5–97.1%. This is a considerable improvement over diagnosis by clinicians using radiographs alone, with sensitivity varying from 19% to 94%.11 Deep CNNs have great potential for improving the sensitivity of dental caries diagnosis and this, combined with their speed, makes them one of the most efficient tools used in this domain.

Orthodontics ANNs have immense potential to aid in the clinical decision-making process. In orthodontic treatments, it is essential to plan treatments carefully to achieve predictable outcomes for patients. However, it is not uncommon to see teeth extractions included in the orthodontic treatment plan. Therefore, it is essential to ensure that the best clinical decision is made before initiating irreversible procedures. An ANN was used to help determine the need for tooth extraction before orthodontic therapy in patients with malocclusion.12,13 The four constructed ANNs, taking into consideration several clinical indices, showed an accuracy of 80–93% in determining whether extractions were needed to treat patients’ malocclusions.12,13

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Use of Artificial Intelligence in Dentistry: Current Clinical Trends and Research Advances

Periodontics According to the 1999 American Academy of Periodontology classification of periodontal disease, 2 clinical types of periodontitis are recognized: aggressive (AgP) and chronic (CP) forms.14 Because of the complex pathogenesis of the disease, no single clinical, microbiological, histopathological or genetic test or combination of them can discriminate AgP from CP patients.15 Papantanopoulos and colleagues16 used an ANN to distinguish between AgP and CP in patients by using immunologic parameters, such as leukocytes, interleukins and IgG antibody titers. The one ANN was 90–98% accurate in classifying patients as AgP or CP. The best overall prediction was made by an ANN that included monocyte, eosinophil, neutrophil counts and CD4+/CD8+ T-cell ratio as inputs. The study concluded that ANNs can be employed for accurate diagnosis of AgP or CP using relatively simple and conveniently obtained parameters, such as leukocyte counts in peripheral blood.

Figure 1: Schematic representation of the architecture of neural networks. Artificial neural networks are structures used in machine learning. They contain many small communicating units called neurons, which are organized in layers. a. Shallow neural networks are composed of an input layer, a few hidden layers and an output layer. b. Deep neural networks have an input layer, multiple hidden layers and an output layer. c. Convolutional neural networks use filters to scan a small neighbourhood of inputs.

Various non-surgical and surgical methods have been devised for the treatment of periodontally compromised teeth (PCT) and supporting structures.17 Despite advances in treatment modalities, no significant improvement has been made in the method for diagnosing and predicting the prognosis of PCT. Clinical diagnostic and prognostic judgement depends heavily on empirical evidence.18


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Lee and coworkers19 evaluated the potential utility and accuracy of deep CNN algorithms for diagnosing and predicting PCT. Using the CNN algorithm, the accuracy of PCT diagnosis proved to be 76.7–81.0%, while the accuracy of predicting the need for extraction was 73.4–82.8%. The noted difference in accuracy seemed to occur between different types of teeth, with premolars more accurately diagnosed as PCTs than molars (accuracies were 82.8% and 73.4%, respectively). This could be explained by the fact that premolars normally have a single root, whereas molars have 2 or 3 roots, thus exhibiting a more complex anatomy for a CNN to interpret.

Endodontics Although mandibular molars tend to have similar root canal configurations, several atypical variations may occur.20 To minimize treatment failures related to morphological differences and to optimize the clinical outcomes of endodontic therapy, cone-beam computed tomography (CBCT) has become the gold standard. However, because of its higher dose of radiation compared with conventional radiographs,21 CBCT is not used systematically. To overcome such challenges, AI has been introduced to classify the given data using a CNN22 to determine whether the distal root of the first mandibular molar has 1 or more extra canals. Radiographs of 760 mandibular first molars taken with dental CBCT were analyzed. Once the presence or absence of the atypia was determined, image patches of the roots obtained from corresponding panoramic radiographs were processed by a deep-learning algorithm to classify morphology. Although the CNN had a relatively high accuracy of 86.9%,20 several limitations exist regarding its clinical integration. The images must be segmented manually,23 which consumes a considerable amount of time. Furthermore, the obtained images must be of adequate size and should focus on a small region to allow the system to concentrate on the object being studied, while covering enough area to include pertinent information.24

Oral Pathology Detection and diagnosis of oral lesions is of crucial importance in dental practices because early detection significantly improves prognosis. As some oral lesions can be precancerous or cancerous in nature, it is important to make an accurate diagnosis and prescribe appropriate treatment of the patient. CNN has been shown to be a June 2021

promising aid throughout the process of diagnosis of head and neck cancer lesions. With specificity and accuracy at 78–81.8% and 80–83.3%, respectively (compared with those of specialists, which were 83.2% and 82.9% respectively), CNN shows great potential for detecting tumoural tissues in tissue samples or on radiographs.25,26

legal system is based on the fundamental assumption that fault and crime are ultimately attributable to humans, substituting humans with autonomous agents raises numerous questions of legal and ethical order. These issues will continue to represent a considerable challenge to our legal system for the foreseeable future.

One study used a CNN algorithm to distinguish between 2 important maxillary tumours with similar radiologic appearance but different clinical properties: ameloblastomas and keratocystic odontogenic tumours.26 The specificity and the accuracy of diagnosis by the algorithm were 81.8% and 83.3%, respectively, comparable with those of clinical specialists at 81.1% and 83.2%. However, a more significant difference was observed in terms of diagnostic time: specialists took an average of 23.1 minutes to reach a diagnosis, while the CNN achieved similar results in 38 s.26

Finally, the transparency of AI algorithms and data is a substantial issue. The quality of predictions performed by AI systems relies heavily on the accuracy of annotations and labeling of the dataset used in training. Poorly labeled data can lead to poor results.30 Clinic-labeled datasets may be of inconsistent quality, thus limiting the efficacy of the resultant AI systems.

Challenges of AI The management and sharing of clinical data are major challenges in the implementation of AI systems in health care. Personal data from patients are necessary for initial training of AI algorithms, as well as ongoing training, validation and improvement. Furthermore, the development of AI will prompt data sharing among different institutions and, in some cases, across national boundaries. To integrate AI into clinical operations, systems must be adapted to protect patient confidentiality and privacy.27 Thus, before considering broader distribution, personal data will have to be anonymized.28 Even with the ability to take these precautions, there is skepticism in the health care community about secure data sharing. AI systems are also associated with safety issues. Mechanisms must be created to control the quality of the algorithms used in AI. To remedy this situation, the United States Food and Drug Administration has created a new drug category, “Software as Medical Device,” through which it regulates safe innovation and patient safety.29 Ambiguous accountability in the use of AI systems is another concern. Who will be held responsible for a patient who faces unintentional consequences resulting from an error or adverse event caused by the AI technology? Is it the professional’s fault, or is it the fault of the developer who built the algorithm? Given that our

Furthermore, health care professionals should possess a full understanding of the decisions and predictions made by an AI system, as well as the capability to defend them.31 Interpretability of AI technology is a known problem, and major advances are required before certain classes of algorithms, such as neural networks, can make clinical diagnoses or treatment recommendations with full transparency.29

Conclusion Although multiple studies have shown potential applications of AI in dentistry, these systems are far from being able to replace dental professionals. Rather, the use of AI should be viewed as a complementary asset, to assist dentists and specialists. It is crucial to ensure that AI is integrated in a safe and controlled manner to assure that humans retain the ability to direct treatment and make informed decisions in dentistry. The road to successful integration of AI into dentistry will necessitate training in dental and continuing education, a challenge that most institutions are not currently prepared for. In addition, AI plays a critical role in virtual reality (VR) and augmented reality (AR). A new term, mixed reality, incorporates aspects of generative AI, VR and AR into computer-superimposed information overlays to enhance learning and surgical planning.32 As various AI systems for diverse dental disciplines are being developed and have produced encouraging preliminary results, a future for AI in the health care system cannot be discounted. AI systems show promise as a great aid to oral health professionals.

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Use of Artificial Intelligence in Dentistry: Current Clinical Trends and Research Advances



1. Yu KH, Beam AL, Kohane IS. Artificial intelligence in healthcare.

chaotic dynamical process. J Periodontol. 2013;84(10):e29-39.

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Orthodontics Mays Al-Nadawi Private Practice, Dubai, UAE Neal D. Kravitz Private Practice, South Riding, Va, USA Ismaeel Hansa Private Practice, Durban, South Africa Laith Makki Assistant Professor, Department of Orthodontics, European University College, Dubai, UAE Donald J. Ferguson Professor and Dean, Department of Orthodontics, European University College, Dubai, UAE Nikhilesh R. Vaid Professor, Department of Orthodontics, European University College, Dubai, UAE

Effect of clear aligner wear protocol on the efficacy of tooth movement: A randomized clinical trial Abstract Objectives: To compare the efficacy of orthodontic tooth movement with three aligner wear protocols: 7 day, 10 day, and 14 day. Materials and Methods: Eighty patients were randomly allocated into three groups: group A (7-day changes), group B (10-day changes), and group C (14-day changes). The posttreatment scans were compared with the final virtual treatment simulations through digital superimposition. The differences between predicted and actual achieved treatment outcomes were computed in six angular and six linear dimensions. Differences .0.5 mm for linear measurements and .28 for angular measurements were considered clinically relevant. Results: Within groups, and irrespective of wear protocol, all linear discrepancies in both jaws were deemed clinically insignificant (,0.5 mm) while nearly all angular discrepancies were considered clinically significant (.2.08). When the three groups were compared,

group C (14-day changes) showed significantly greater accuracy in the posterior segment for maxillary intrusion, distal-crown tip and buccal-crown torque, and mandibular intrusion and extrusion. The mean treatment duration in the 7-day aligner change group was nearly half that of the 14-day aligner change group (5 months vs 9 months). Conclusions: Fourteen-day changes were statistically significantly more accurate in some posterior movements. However, this difference in accuracy did not exceed the threshold for clinical significance (.0.5 mm/.2.08). Achieving a clinically similar accuracy between the 7-day protocol and 14-day protocol in half the treatment time suggests a 7-day protocol as an acceptable treatment protocol. Clinicians may consider slowing down to a 14-day protocol if challenging posterior movements are desired. (Angle Orthod. 2021;91:157–163.) Keywords: Invisalign; Wear protocol; Aligner efficacy; Clear aligner therapy


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Clear aligner therapy (CAT) is an accepted mainstay of orthodontic mechanotherapy.1–5 Studies have evaluated the biological,2–4 esthetic,5,6 and psychological7–10 advantages that CAT may provide over conventional preadjusted edgewise appliances. Although CAT is fast gaining popularity among care seekers, there are still unanswered questions regarding the efficacy and efficiency of these appliances. Evidence-based literature on the efficacy of Invisalign (Align Technology, Santa Clara, Calif), and CAT in general, is still in its incipient stages.9,11–14 In 2009, Kravitz et al.15 evaluated the accuracy of anterior tooth movement using Invisalign by June 2021

comparing the predicted and achieved tooth movement and reported a mean overall accuracy of 41%. A recent followup to this study by Haouili et al.16 suggested that the mean accuracy improved to 50% in 2020. In a 2017 retrospective study, Grunheid et al.3 concluded that Invisalign was able to achieve predicted tooth positions with high accuracy in nonextraction cases. Invisalign aligners are to be worn 20–22 hours per day and to be changed sequentially every 7 days as per current protocols from the manufacturer. Previously, however, the recommended wear schedule was 14 days. In the literature, there is limited evidence to support either wear schedule. Drake et al.17 reported that more orthodontic tooth movement occurred during the first week than during the second week of aligner wear. The reduction in tooth movement seen during the second week was not related to material fatigue.

To date, no independent study has evaluated the efficacy of tooth movement with different aligner wear protocols (7 day, 10 day, 14 day). A better under- standing of the optimal aligner wear protocol would help both clinicians and patients improve efficiency. Hence, the purpose of this randomized clinical study was to evaluate and compare the efficacy of different orthodontic tooth movements with different aligner wear protocols (7 day, 10 day, 14 day) by comparing the predicted treatment outcome vs actual outcome. The null hypothesis was that there would be no difference in the efficacy of orthodontic tooth movement with aligners changed every 7 days, 10 days, or 14 days.

Materials and methods Trial Design

Only two published clinical trials have investigated optimal aligner wear protocol. Bollen et al.18 compared the effects of material stiffness (soft, hard) and activation time on the patient’s ability to complete a prescribed series of aligners. The 2-week activation period almost doubled the likelihood for successful completion of the initial series of aligners compared with 1-week activation. A high Peer Assessment Rating (PAR) score and planned extractions substantially decreased the likelihood that the initial aligner series would be completed. This study tended to support 2-week activation time in patients who did not require premolar extractions. In the second clinical trial, Clements et al.19 measured the effects of material stiffness and activation time on the quality of treatment and dental improvement measured by changes in PAR scores and the irregularity index. The authors conclud- ed that there was no significant difference between 1-week and 2-week aligner change frequency protocols. The landmark studies of Bollen et al.18 and Clements et al.19 were performed in 2003 and marked the beginning of independent prospective clinical research regarding CAT and Invisalign. Invisalign has continually improved through the development of new aligner materials, modifications of attachments, and staging of tooth movements.16 The exact extent to which new aligner material influences treatment efficacy still requires investigation. According to the company’s internal data, an analysis comparing tooth movement predictability in 200 cases showed no difference in predictability or refinement rates between 1- or 2-week aligner changes.

The study was a three-arm parallel randomized clinical trial with a balanced allocation ratio (1:1:1). This study was approved by the Institutional Review Board of European University College (Dubai Healthcare City, United Arab Emirates), IRB number EUC-IRB-17.2.12.

Sample One hundred twenty consecutive patients were assessed for eligibility at a single orthodontic practice in South Riding, Virginia, USA. The orthodontist (Dr Kravitz) who prescribed all ClinCheck (Align Technology Inc, Santa Clara, Calif) treatment plans was highly skilled and experienced (Tier-Level Diamond Plus Provider [formerly Top 1% Elite] with more than 2500 Invisalign cases treated). Prospective participants for the study were informed about the research and treatment protocol and provided informed consent to participate in the study. Patients were selected based on the following inclusion criteria: malocclusion to be treated with Invisalign aligners (SmartTrack) with a total initial sequence between 17 and 25 aligners, permanent dentition, good oral hygiene, and no extractions. Exclusion criteria included the following: use of auxiliary appliances, oral surgery, and previous orthodontic treatment or dental restorations placed during treatment. A total of 80 treated patients fit the inclusion criteria and were then randomized using the Random function in Excel (Microsoft Office 2019, Seattle, WA) with a 1:1:1 allocation ratio. The participants were randomly assigned to one of the following


Effect of clear aligner wear protocol on the efficacy of tooth movement: A randomized clinical trial

three groups: group A changed aligners every 7 days; group B changed aligners every 10 days; and group C changed aligners every 14 days. The records of five subjects were not adequate for data collection; hence, a final sample size of 75 was analyzed (Figure 1; Table 1).

The virtual treatment plan models exported from ClinCheck Pro were segmented to isolate each tooth as a separate object and compared with the unsegmented intraoral scans. Corresponding dental arches were first aligned globally, and then individual teeth from a segmented model were superimposed on analogous teeth of an unsegmented model using a best-fit algorithm so that differences between tooth positions could be computed. The differences between the positions of each tooth in the two digital models were quantified in the following six dimensions: mesial- distal, buccal-lingual, occlusal-gingival, tip, torque, and rotation (Figure 2). Data from the patient’s dentition were organized into four categories: maxillary and mandibular anterior and posterior dentition (posterior dentition included second molars, first molars, second premolars, and first premolars; anterior dentition included canines, lateral incisors, and central incisors). The software used for the superimpositions allowed researchers to detect differences that were too small to be clinically relevant. The threshold values were therefore chosen in reference to the American Board of Orthodontics (ABO) model grading system as described by Grunheid et al.3 According to the ABO, alignment discrepancies of 0.5 mm or greater in marginal ridges and contact points would result in point deductions.

Figure 1: CONSORT flow chart.

To reduce the risk of bias, the randomization was undertaken by an author who had not examined any of the patients; hence, the treating orthodontist was blinded to the initial allocation. Thereafter, however, blinding was not feasible for the treating doctor due to the nature of treatment. Data collectors and outcome assessors were blinded for analysis. The stereolithography files of the final stage of each patient’s virtual treatment plan were exported through ClinCheck, which represented the predicted tooth movement. The actual outcome was obtained using three-dimensional (3D) intraoral scans (Itero Element, Align Technology, San Jose, Calif) taken at final records. The digital models were deidentified and imported into eModel 9.0 Compare software (GeoDigm Corporation, Falcon Heights, Minn). The software uses a best-fit 3D superimposition algorithm allowing for calculation of differences in linear and angular dimensions for individual tooth positions between the two models. This software has been previously tested for reproducibility20 and has been used in previous studies comparing virtual treatment outcomes to achieved treatment outcomes.3,16,21–24


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Furthermore, a marginal ridge discrepancy of 0.5 mm equated to a crown-tip deviation of 28 for an averagesized molar. Thus, clinically significant discrepancies were set at .0.5 mm for linear movements and .28 for angular movements.

Table 1: Sample Distribution June 2021

29 June - 1 July 2021


Effect of clear aligner wear protocol on the efficacy of tooth movement: A randomized clinical trial

Figure 2: Superimposition of digital models to compute differences between predicted and achieved tooth positions. (Left) Global alignment of posttreatment model (white) and final virtual treatment plan model (orange). (Right) Superimposition of individual teeth of final virtual treatment model (green) and posttreatment model (white) using best-fit surface-based registration.

Statistical Analysis All data were collected and stored in Excel and analyzed using SPSS software (version 15.0.1, IBM, Armonk, NY). Descriptive statistics were computed for the differences between predicted and actual achieved tooth positions in each of the six directions. Interval data were tested for normal intragroup distribution using the Shapiro-Wilk test. Independent t-tests were then used to asses intragroup differences. Intergroup differences were assessed using analysis of variance and the Scheffe post hoc test. P-values ,.05 were considered statistically significant.

Results A comparison of subject demographics suggested homogeneity (P . .05) of the three samples for group age and number of aligners per jaw. Heterogeneity (P , .05) was suggested for gender, Angle classification, and mean treatment time (Table 1). In the maxillary dentition, group C (14 day) achieved significantly (P , .05) higher accuracy compared with group A (7 day) for posterior intrusion (0.3 mm vs 0.4 mm), distal crown tip (2.88 vs 3.98) and buccal crown torque (2.88 vs 4.48) (Table 2). In the mandibular dentition, group C achieved significantly (P , .05) higher accuracy compared with groups A and B for posterior intrusion (0.3 mm vs 0.4 mm) and extrusion (0.2 mm vs 0.3 mm) (Table 2).


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Within groups, all linear discrepancies for the posterior and anterior segments in both the maxillary and mandibular arches for all three groups were clinically insignificant (,0.5 mm). In contrast, all discrepancies for angular movements in both arches were clinically significant (.28) except for two variables in group C: mesial rotation (1.98) in the maxillary posterior segment and buccal crown torque (1.98) of the mandibular anterior segment (Table 2).

Discussion In this prospective trial, the three groups (7-day, 10-day, and 14-day wear) were homogeneous for age and number of aligners. Heterogeneity (P , .05) was suggested for gender, Angle classification, and mean treatment duration. It should be noted that the amount of interproximal reduction performed or number of attachments used was decided on a patient-to-patient basis, although each arch averaged approximately six attachments and ,1 mm of interproximal reduction. The mean treatment duration required to finish the initial set of aligners in the 7-day group (5 months) was, as expected—almost half compared with the 14-day group (9 months). This result was significant in lieu of the findings in this study showing no clinically relevant differences in accuracy of tooth movement among the three groups. Within the groups, there were no clinically significant linear discrepancies between achieved and predicted tooth June 2021

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Effect of clear aligner wear protocol on the efficacy of tooth movement: A randomized clinical trial

positions (.0.5 mm). In contrast, all angular movement discrepancies for all three groups were .28 and therefore considered clinically significant (Table 2). Hence, even with 14-day changes, clinicians must consider overcorrections to achieve the desired angular movements. These results agree somewhat with those of Simon et al.,14 who found that molar distalization, a linear movement, was predictable. Incisor torque and premolar rotations, on the other hand, were more challenging and less accurate. Although both Grunheid et al.3 and Charalampakis et al.4 found mandibular incisor intrusion to be an inaccurate movement (contrary to the findings in this study), Grunheid et al. 3 also found molar torque as well as mandibular lateral incisor, canine, and first premolar rotations to be inaccurate, while Charalampakis et al.4 found maxillary canine, mandibular premolar, and canine rotations; again, all angular movements, to be most inaccurate.

These findings may have been due to the flexibility of the aligner material, combined with the nonrigid nature of the aligner to tooth-surface contact, precluding torsion and tipping control. Attempting overcorrection in the digital predictions, incorporation of composite attachment designs and additional refinement aligners are possible solutions for this (Table 2). When the differences between predicted and achieved tooth movements were compared among 7- day, 10-day, and 14-day aligner changes, there were no statistically significant differences for all linear and angular movement in the anterior segments in both arches (P . .05). With regard to the posterior segment, however, group C (14-day change) was statistically more accurate for intrusion, distal-crown tip, and buccal-crown torque in the maxillary arch as well as intrusion and extrusion movements in the mandibular arch.

Table 2: Predicted Achieved Differences in the Maxilla and Mandible


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June 2021

Although these differences were not clinically significant, the trend supported greater accuracy in the 14-day protocol, as previously found by Bollen et al.18 This could be due to the larger root surface areas of molars that require greater control for linear and angular tooth movements.25 It seemed that aligners using the same material stiffness in both anterior and posterior segments would have greater difficulty delivering loads suitable in the posterior segments.

Finally, the patients in this sample had an initial number of aligners between 17 and 25 and short treatment durations, thus indicating relatively simple treatments. The results may have differed if more difficult cases, with more challenging tooth movements, were included.

With the use of mathematical superimposition of digital models, it has become feasible to quantify treatment changes and, as in the present study, to determine differences between virtual treatment simulations and actual treatment outcomes. The software used in this study (eModel 9.0 Compare software) was able to quantify differences between objects with respect to six degrees of freedom. The software calculated differences automatically, without being influenced by potential operator bias. However, this method measured only intra-arch discrepancies and did not measure interarch relationships, such as overbite, overjet, and occlusal contacts.

• Within groups, all linear discrepancies demonstrated clinically insignificant differences (,0.5 mm). In contrast, nearly all angular discrepancies were clinically significant (.2.08).

The findings in this study seemed to suggest that a 7-day protocol was generally sufficient as there was no clinically significant difference compared with a 10-day or 14-day protocol. A 7-day protocol did, however, significantly reduce treatment duration. It could be suggested that, for those cases requiring complex movement of posterior teeth, a 14-day change of aligners may be beneficial. In the near future, personalized aligner change protocols may be used to enhance aligner efficiency.26,27

Limitations A limitation of 3D superimposition was the lack of stable anatomic structures on the predicted models, as stereolithography files exported from ClinCheck contained only the clinical crowns and virtual gingiva. In addition, the ClinCheck plan was simply a visual representation of force systems, rather than a true prediction of final tooth position; hence, the predicted tooth position may not have actually been the one desired.16 Patient compliance and inaccuracies from the clinician during attachment placement and inter- proximal reduction may also have affected tooth movement. This study also relied on the clinical decisions made by one (albeit experienced) orthodontic provider and may not be externally valid for all orthodontists, who vary in their preferences for toothmovement sequencing, attachment design, and extent of overcorrections.


• The 14-day wear protocol showed statistically greater accuracy for some posterior tooth movements: maxillary intrusion, distal-crown tip, and buccal-crown torque as well as mandibular intrusion and extrusion. None of them exceeded the clinically significant threshold (.0.5 mm or .28). • Achieving a clinically similar accuracy between the 7-day protocol and 14-day protocol in half the treatment time suggests that a 7-day protocol is an acceptable treatment protocol. • However, if challenging posterior tooth movements or angular movements (ie, torque, tip, and rotation) are required, the 14-day protocol should be considered.


Effect of clear aligner wear protocol on the efficacy of tooth movement: A randomized clinical trial



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exposants internationaux

100 450 séances de formation


Innovation Andreas Brandstätter Strategic Product Manager for Oral Surgery and Implantology

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1. Mr Brandstätter, what does ‘Implantmed’ brand stand for?


Brandstätter: For me, it’s quite clear: Implantmed is your go-to partner for oral surgery and implantology. The popular product brand is now synonymous with dental implantology and is commonly used as a term for implantology motors in dental practices.

2. What makes Implantmed a must-have in dental implantology? Brandstätter: We offer a reliable, robust and durable drive unit, which is easy to operate. At the same time, we provide a flexible workflow solution with optional extra product features that are ideally suited to the user’s individual working style. We make sure that Implantmed is always


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Andreas Brandstätter is particularly proud of the short and powerful motor including thermo washer disinfectable and sterilizable cable. June 2021

an easy to operate drive unit with a high-torque motor for dental implantology and maxillary surgery; the result was Implantmed. And it still fulfils these criteria today. Implantmed is constantly being updated with innovations such as an LED supply on the motor, a function for measuring implant stability, wireless foot control, precise torque monitoring, and many other functions. A glass display with touch screen also enables better disinfection and therefore optimal hygiene.

6. Why is Implantmed so popular among dentists? Brandstätter: Because it is reliable, durable and easy to use; this enables the user to fully concentrate on treating the patient. But we really would need to ask our customers who work with Implantmed every day. And this is something we do regularly. We had a great response from Dr Romana Krapf, for example, who runs a group practice with her father in Weißenhorn, Germany. She explained to us that her father was already working with Implantmed 20 years ago and that she is still using the same device today, as it fits perfectly into her workflow. This alone says a great deal. We also support the work of the Dentists Without Limits Foundation (DWLF) in Siavonga, Zambia, where our Implantmed device is in use. Dr Fridleif Bachner from Germany, who often works on site at DWLF, is delighted with the robustness of the W&H device.

Implantmed – 20 Years of Pioneering Spirit!

4. This means each Implantmed generation is always a step ahead. What is the secret to W&H’s success? Brandstätter: That’s easy – our focus on the customer and the commitment of each and every employee. Another secret to our success is the perfect interplay of man and machine; expertise and technology go hand in hand here and this is reflected in Implantmed.

5. What technological milestones are you particularly proud of? Brandstätter: We should be proud of every Implantmed generation. My personal highlight is the short and powerful motor including thermo washer disinfectable and sterilizable cable. This was a key milestone for the industry with which we can offer extra comfort and safety for the user and the patient alike.

In Implantmed Plus, implantologists have a powerful device with optional extra features.


Implantology meets Implantmed

Despite extreme on-site conditions – like dust, heat etc. – Implantmed works reliably and smoothly. Implantmed is thus not only an important tool in clean room surgeries, but also under extreme external conditions in Africa.

7. What role does Implantmed play in the entire W&H product portfolio? Brandstätter: Implantmed is one of W&H’s most popular products. Today, there are Implantmed fans right across the world. As an essential part of our NIWOP workflow (No Implantology without Periodontology), it demonstrates its strength in individual workflow solutions. Countless implant manufacturers around the world place their trust in us and sell Implantmed under their own brand.

8. What can we look forward to next? Brandstätter: Implantmed is increasingly evolving into an innovative systems solution. So, the professional community can certainly look forward to more highlights in the future!


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Always a step ahead! The perfect interplay of man and machine is THE secret to Implantmed’s success for Andreas Brandstätter.

June 2021

MAKE YOUR PLANS NOW! 97th Annual Session


Meeting Dates: November 26th - December 1st, 2021 Exhibit Dates: November 28th - December 1st, 2021 IN-PERSON AT THE JACOB K. JAVITS CONVENTION CENTER, NEW YORK CITY RI








Special Care Dentistry Forum






Endodontic Overview of Root Resorption The Seventh Live Webinar organized by Dental News was presented by the leading speakers and panelists in the world of dentistry on May 16th, 2021, with dentists and specialists registered from around the world. The Topic of this Webinar was “Endodontic Overview of Root Resorption”, with Dr Omar Abusteit as main speaker. After the presentation, our international panelists: Pr Hassan Selim, Pr Khaled Merdad, Pr Edmond Koyess and Pr Ahmed Abdelrahman discussed the topic and answered the questions asked by the participants.

Abstract In modern dentistry, we are often presented with patients exhibiting various types of root resorption. This presentation will discuss etiology, classification, and management of root resorption illustrated with numerous clinical challenges. The aim is to guide the clinician through accurate diagnosis, effective treatment

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planning, and execution of clinical procedures supported by the best available evidence. Rationale of surgical and non-surgical treatment options will be emphasized, incorporating recent technology and clinical tips to provide favorable patientcentered outcomes.

June 2021

Speaker Dr. Abusteit was born and raised in Egypt where he earned his dental degree from Cairo University and practiced general dentistry for a few years before moving to the USA to pursue postgraduate studies in endodontics. He received fellowships in Endodontics from UCLA School of Dentistry and Medical University of South Carolina College of Dental Medicine. Later, he completed his endodontic specialty training and earned a Master of Science in Dentistry from the Medical University of South Carolina where he also served as the chief endodontic resident. Dr. Abusteit is a diplomate of the American Board of Endodontics and he is currently serving as an Assistant Professor in the Division of Endodontics at the University of Minnesota School of Dentistry and he maintains a private practice limited to microendodontics in Minneapolis, Minnesota. Dr. Abusteit has lectured and presented on various endodontic topics in conferences, meetings, and study clubs nationally and internationally. He is an active member of the American Association of Endodontists, American Dental Association, and several other dental organizations.


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Dentsply Sirona acquired assets of Propel Orthodontics Innovation

a leading innovator in orthodontic devices Dentsply Sirona today announced that it has acquired substantially all of the assets of Propel Orthodontics, including the VPro device and the Fastrack Mobile App. Propel Orthodontics is a leading innovator, manufacturer, and worldwide seller of orthodontic devices. Propel Orthodontics offers in-office and at-home orthodontic solutions to dentists and their patients. The acquisition is an important step for Dentsply Sirona to further strengthen its position in the fastgrowing clear aligner market. The acquired product lines perfectly complement the Byte® and SureSmile® businesses. The acquisition of the assets of Propel Orthodontics will open up significant opportunities for Dentsply Sirona to drive innovation in the field of clear aligner and orthodontic treatment. The products lines Dentsply Sirona is acquiring are a key

Figure 1: Dentsply Sirona is the world’s largest manufacturer of professional dental products and technologies.


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differentiator as they improve treatment times and patient comfort. They also add digital capabilities to Byte and SureSmile to improve patient engagement and treatment monitoring. The at-home High Frequency Vibration (HFV) product line consists of the VPro5®, VPro+™, and VPro™ and supports both active treatment and retention at just 5 minutes per day. When used as part of an orthodontic treatment plan, this easy-to-use device featuring patented high frequency vibrational technology can increase patient comfort and may reduce overall treatment time significantly. Moreover, following the acquisition, Dentsply Sirona will continue to enhance the VPro Fastrack App, which helps patients and providers remotely monitor the orthodontic treatment plan. “With the acquisition of the assets of Propel Orthodontics, Dentsply Sirona

Figure 2: Propel Orthodontics is a leading innovator, manufacturer, and worldwide seller of orthodontic devices.

June 2021

Due to the different approval and registration times, not all technologies and products are immediately available in all countries.

About Propel Orthodontics Propel Orthodontics is a leading innovator, manufacturer and worldwide seller of orthodontic devices with offices in Briarcliff Manor, New York, and San Jose, California. The company provides in-office and at-home orthodontic accessory devices to orthodontists and their patients, including the VPro5™, a vibratory orthodontic device used to properly seat aligners in 5 minutes a day.

Figure 3: Don Casey, Chief Executive Officer at Dentsply Sirona

takes another step to position the company as a leading innovator in the fast-growing clear aligner market. It is the perfect match to Byte, and our SureSmile business, and is also a strong strategic fit with Dentsply Sirona. The acquisition supports innovation in the orthodontics space of Dentsply Sirona as well as the capacity to further invest in the future product development in this area,” says Don Casey, CEO of Dentsply Sirona. Byte, which was acquired by Dentsply Sirona in December 2020, already includes the VPro product, labeled as HyperByte, in every treatment. Dentsply Sirona will also work on launching new branding as part of the SureSmile portfolio for the professional market after the integration of the assets of Propel Orthodontics and will continue to sell VPro directly to dental professionals. Patients will benefit from the acquisition as they will have the opportunity to use the VPro product line with more offerings in the future. This contributes to the two companies’ goals of providing more patients with access to simple and comfortable oral care.

Figure 4: The product VPro improves treatment times and patient comfort.


VisCalor – the world’s first thermoviscous restorative material, now also available for all cavity classes With VisCalor, a universal variant indicated for all cavity classes is now added to the world’s first thermoviscous bulk fill composite. While the bulk-fill variant, VisCalor bulk, focuses on simple and quick posterior restorations, VisCalor now makes highly aesthetic anterior restorations possible, thanks to its large range of VITA shades, including an additional, translucent shade. Both products are based on the unique thermoviscous technology. VisCalor reaches a low viscosity through extraoral heating, allowing for an application that resembles that which you are used to with flowables.


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The material flows optimally onto cavity walls and undercut regions. Then the material cools down to body temperature quickly, becomes highly viscous and can be modelled like a classic packable composite without any delay. Uniting two different viscosities in one product guarantees fast and easy handling, since separate steps such as lining and covering layers are no longer required. In addition, VisCalor is compatible with all conventional bonding agents. Thus, VisCalor offers not just a highquality and aesthetic restoration, but also an economical alternative to conventional composites.

June 2021

VOCO – The Dentalists The family-run dental company VOCO located in Cuxhaven is one of the leading manufacturers in the industry, both nationally and internationally. The product portfolio comprises more than 100 preparations, with a focus on preventive, restorative, prosthetic and digital dentistry. All products are manufactured at the headquarters and are therefore 100 percent “Made in Germany”. 440 people are employed in the departments of research, production and administration in Germany. Another 400 employees are responsible for sales worldwide and take care of dentists and depots on site. VOCO relies on dental products of highest material quality and user-friendliness that meet the high demands of the market. Thanks to innovative solutions, the company, founded in 1981, often takes on pioneering roles and establishes new standards in the dental world. In addition, VOCO consistently pushes the digital dentistry and combines complex technologies with best user comfort. VisCalor SingleDose Caps are characterised by their particularly long and slender cannula. This allows direct application, even in hard-to-reach areas and narrow cavities, as well as bubble-free application, which contributes to the durability of the restoration. The longevity and stability of the material are the result of its excellent physical properties: With a filler content of 83% by weight as well as very low shrinkage of only 1.4%, VisCalor is in a class of its own among composite materials. The Caps Warmer is ideally suited for heating VisCalor and allows for up to 4 caps to be heated at the same time. This is especially advantageous when working with multiple increments or also with multiple shades. Thanks to its unique technology, VisCalor creates the ideal preconditions for excellent handling, simple application, as well as high-quality and long-lasting restorations of highly aesthetic appearance – for all cavity classes.

Press contact Kerstin Hastedt, VOCO GmbH – Public Relations E-Mail:

Expodental Meeting

postponed to September! Once again UNIDI is struggling with the uncertainty due to the Covid-19 pandemic in Italy and in Europe. Following several discussions and meetings with different companies, exhibitors, associations and partners, the UNIDI board decided to postpone Expodental Meeting to September 9th to 11th, 2021.

This was regarded as the best choice, considering that the rollout of vaccinations is underway and the month of September should allow us to meet in Rimini in much safer condition. Expodental Meeting is keen on the health and well-being of its audience and firmly willing to guarantee the maximum safety for exhibitors and visitors, in order to allow as many people as possible to attend. The Organizing Committee aims to make the leading dental fair in Italy not to disappoint the expectations of the whole dental sector. This is especially important


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for this year’s edition since our dental industries will benefit more than ever from a successful event. «Today, considering what happened from the beginning of 2020, predicting the near future is no longer possible. Unfortunately, the recent weeks have made it more and more obvious that the month of June does no longer represent the ideal time for an effective restart» says Gianfranco Berrutti, UNIDI president. «Postponing Expodental Meeting to September was a choice dictated by our desire to confirm the leadership of our event, a fundamental tool for promotion and business for the whole sector.»

Rendez-vous in Rimini, then, from 9 to 11 September 2021, with an exhibition area and a scientific and training program that will not disappoint the expectations.

March 2021

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