International Dentistry Australasian Edition - Vol. 13, No. 4 - 2018

VOL. 13 NO. 4 IN THIS ISSUE

Walter Denner Successful outcome following trauma Johan Christian Julyan and Marius Coetsee Class II Division 1 treatment using a twophase approach – a case report Casper H Jonker and Carel (Boela) van der Merwe Removal of fractured endodontic instruments: A report of two cases Osvaldo Zmener and Cornelis H Pameijer Adhesive dentistry meets restorative dentistry and endodontics – part two Johan Hartshorne Essential guidelines for using cone beam computed tomography (CBCT) in implant dentistry. Part 2: Clinical considerations

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Contents Volume 13 No. 4

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4

Clinical Successful outcome following trauma Walter Denner

10

Clinical Class II Division 1 treatment using a two-phase approach – a case report Johan Christian Julyan and Marius Coetsee

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28

Clinical Removal of fractured endodontic instruments: A report of two cases Casper H Jonker and Carel (Boela) van der Merwe

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Clinical Adhesive dentistry meets restorative dentistry and endodontics – part two Osvaldo Zmener and Cornelis H Pameijer

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Clinical Essential guidelines for using cone beam computed tomography (CBCT) in implant dentistry. Part 2: Clinical considerations Johan Hartshorne

62 Products

VOL. 13, NO. 4 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION 1

Townsville leaders honoured at Buckingham Palace We are thrilled to announce that Dr Daryl Holmes, Managing Director of 1300SMILES and Mr Ken Mulligan, Managing Director of YWAM Medical Ships were honored by Her Royal Highness Princess Anne in a ceremony at Buckingham Palace in October this year. The two Townsville locals were acknowledged for their service in Papua New Guinea (PNG).

Mr Mulligan and Dr Holmes have both been awarded with an Officer of the Most Excellent Order of Ken Mulligan (left) with Daryl Holmes (right). the British Empire (OBE). Mr Mulligan received the award in acknowledgement for his services to the community and rural healthcare through YWAM Medical Ships, and Dr Holmes was recognised for services to health through support for YWAM Medical Ships.

YWAM Medical Ships Managing Director, Mr Ken Mulligan, said that the esteemed award is a wonderful acknowledgement that helps affirm and strengthen YWAM’s commitment to PNG. “We receive this honour on behalf of so many people who have worked tirelessly and voluntarily for the people of Papua New Guinea.

“I am so grateful to our donors, hard-working volunteers, and the many supporters and friends who have helped make this possible. To receive this award beside Daryl yesterday was very special – he is a good friend and one of many who have helped us touch so many lives,” said Mr Mulligan.

Dr Daryl Holmes has supported YWAM Medical Ships since they began their operations in 2010. Dr Holmes’ support has included volunteering as a dentist on YWAM’s medical ships on an annual basis, promoting volunteering opportunities to 1300SMILES’ staff and dentists, and connecting YWAM with major dental companies – including Henry Schein Halas, who fitted out the dental clinic onboard the MV YWAM PNG in 2015.

Dr Holmes said the investiture yesterday was a humbling experience.

“It has been a joy to work with YWAM Medical Ships over the last 8 years, the journey has been life-changing for me and for 1300SMILES. “When I reflect on the villages I’ve visited and the patients I’ve treated – it really is nothing short of a privilege and an honour,” said Dr Holmes.

The MV YWAM PNG is currently on deployment in Central Province. Over 10,000 patients have received treatment and training since the vessel was sent from Townsville in July – one of the patients who received treatment this week was a young mother named Ruth* with an advanced case of Tuberculosis.

“While it is a privilege to receive an OBE this week, my heart continues to go out to individuals who are suffering unnecessarily. Ruth's story reminds us again why we do what we do and we are more determined then ever to continue,” said Mr Mulligan.

Henry Schein through the Henry Schein Cares Foundation are happy to be an ongoing supporter of YWAM Medical Ships. For more information visit their website www.ywamships.org.au

2 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 13, NO. 4

Vol. 13 No. 4 ISSN 2071-7962 PUBLISHING EDITOR Ursula Jenkins

EDITOR Prof Simone Grandini

ASSOCIATE EDITORS Prof Cecilia Goracci Dr Andre W van Zyl

EDITOR-IN-CHIEF EMERITUS Prof Dr Marco Ferrari

EDITORIAL REVIEW BOARD Prof Paul V Abbott Dr Marius Bredell Prof Kurt-W Bütow Prof Ji-hua Chen Prof Ricardo Marins de Carvalho Prof Carel L Davidson Prof Massimo De Sanctis Dr Carlo Ercoli Prof Roberto Giorgetti Dr Patrick J Henry Prof Dr Reinhard Hickel Dr Sascha A Jovanovic Dr Gerard Kugel Prof Ian Meyers Prof Maria Fidela de Lima Navarro Prof Hien Ngo Dr Hani Ounsi Prof Antonella Polimeni Prof Eric Reynolds Prof Andre P Saadoun Prof Errol Stein Prof Lawrence Stephen Prof Zrinka Tarle Prof Franklin R Tay Prof Manuel Toledano Dr Bernard Touati Prof Laurence Walsh Prof Fernando Zarone PRINTED BY KHL PRINTING, Singapore International Dentistry - Australasian Edition is published by Modern Dentistry Media CC, PO BOX 76021 WENDYWOOD 2144 SOUTH AFRICA Tel: +27 11 702-3195 Fax: +27 (0)86-568-1116 E-mail: dentsa@iafrica.com www.moderndentistrymedia.com

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CLINICAL

Successful outcome following trauma Walter Denner1

Injuries to the upper anterior teeth are a common occurrence among children and adolescents. With any luck, it is just a little hard substance that is lost. Taking a patient case as an example, a special technique which can be used to restore both the shape and colour of the teeth reliably will be illustrated. The technique uses a ceramic-based restorative material without conventional monomers.

Almost one child/adolescent in three will require dental treatment for trauma to permanent teeth, and it is usually the upper anterior teeth which are affected.1 Therefore, it is a good idea to be well prepared for such cases, for example with a corresponding checklist2 and a validated treatment concept.3 In addition to the patient’s trauma history, the bone and soft tissue situation is always thoroughly examined and documented, with an x-ray if possible.

In cases with an uncomplicated crown fracture without pulp involvement, the first step is to cover the dentine so as to avoid endodontic infections. Pulp necrosis then only develops in 6% of cases at most.4 If there is no fragment available for adhesive reattachment, the tooth can be restored quickly with a composite material. Indirect restorations, with preference being given to ceramic veneers or partial crowns, are also possible.4 The vitality of the tooth should be checked at least once in the year following the trauma.

In children, the direct technique with composites is generally indicated. Renewed trauma is not unlikely and, furthermore, indirect restorations are more time-consuming and more expensive due to the laboratory costs involved.

Build-up technique with Ormocer® restorative material

1

Dr. Walter Denner, Private Practice, Fulda, Germany, Specialities: Adhesive restorative techniques in the anterior and posterior region; endodontology, implantology.

Contact information: walter@dr-denner.de

In the direct build-up technique, as with all tooth reconstructions, the aesthetic impression is determined by the shape and shade. Build-ups only appear natural if both characteristics are reproduced successfully. The shape can be attained using suitable matrix techniques, which the author has described in detail in a textbook written in cooperation with the inventor of the technique, Dr. Burkhard Hugo, a professor from Würzburg, Germany.5 The principle consists of reproducing the anatomy of the restoration as precisely as possible using the matrix.

This is done by sculpting it from the approximal exterior surface with a temporary composite. Following curing, the permanent material can be introduced into the resulting negative mould in layers. If necessary, a “back wall” can be built up palatally or lingually in addition, using enamel restorative material, for example by layering it against a silicone index. The exact procedure and materials used are described in detail in the following case report.

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Figure 1: An 8 ½-year-old boy hit his upper right central incisor (tooth 11) against a railing when playing. Unfortunately, the fragment of tooth which broke off was lost.

Figure 2: The x-ray shows no signs of a root fracture or alveolar damage.

Figure 3: Following relative isolation, the enamel is carefully bevelled and a transparent matrix fixed in place with a thin wooden wedge.

Figure 4: The matrix is now adapted with a flowable, temporary composite (Clip Flow) as exactly as possible in the form of an anatomical negative mould (cf. Fig. 5). Only then are the enamel margins etched with 36% phosphoric acid for 30 seconds, extending considerably beyond the bevel.

Case report

similar shades from the shade guide of the nanohybrid Ormocer® filling material used (Admira Fusion, VOCO, Cuxhaven, Germany) up to the cervical region of the neighbouring tooth.6 As the dentine is going to be covered over with a layer of enamel material (reference: incisal edge), the initial shade should be chosen one step darker.

Due to the supragingival location of the entire defect, it was possible to do without the application of a rubber dam.

A lip, cheek and tongue retractor was used instead (Arcflex, FGM, SC, Brazil). With the patient under local anaesthetic, the exposed dentine in the central section was covered with light-curing calcium trisilicate liner (TheraCal LC, Bisco) and the enamel bevelled to a width of approximately 0.5 mm

An 8 ½-year-old boy knocked his teeth against a railing while playing at school. He presented in the practice with his mother later that same day. The good news was that the surrounding tissue, including the pulp, had remained intact and the vitality test on the affected tooth 11 (upper right central incisor) was positive (Fig. 1 and 2). The bad news: The fragment was lost in the accident and was therefore not available for the restoration.

With suitable time management (treatment at the end of surgery hours and beyond), we were able to restore the tooth in the same treatment session. Firstly, the dentine shade was determined on the wet tooth by simultaneously holding two

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DENNER

Prior to etching the enamel with 36% phosphoric acid, the anatomically advantageous position of the matrix was ensured with flowable, temporary composite (Clip Flow, VOCO) (Fig. 4). In this modification of the Hugo method, the material, which flows without application of pressure, is injected into the approximal area against the matrix with a fine cannula. At the same time, the matrix is gently pressed, either manually or using a spatula, palatally and vestibularly against the tooth being restored, and the flow material is

cured at the same time. Figure 5 shows the incisal extent of the defect.

Following the application and curing of the universal adhesive (Futurabond U, VOCO) (Fig. 6), the dentine core was then sculpted layer by layer with two different shades of the permanent restorative material (Admira Fusion). To this end, the dentine material in the shade A3 and then A2 was first applied in a "roof tile" fashion, and each was light-cured (Fig. 7).7 Cervically, the material was extended over the bevel so as to avoided a discoloured margin in the restoration.

As the final layer, enamel material (incisal) was applied with a thin, slightly elastic sculpting spatula (Composite 4, American Eagle Instruments, USA) (Fig. 8). When doing so,

Figure 5: Status after etching: The extent of the defect is also clearly visible in the incisal image.

Figure 6: A universal adhesive (Futurabond U) is applied to the enamel and dentine and then cured.

Figure 7: Situation following reconstruction of the dentine core with ceramic-based restorative material in shades A2 and A3: The reconstruction is performed in two layers so as to allow better intraoperative assessment of the dimensions.

Figure 8: Application and sculpting of the enamel shade with a coated spatula.

(Fig. 3). A transparent piece of matrix was then fixed vertically in the interproximal space with a thin wooden wedge (Dr. Barman’s Anatomical Wedges) (Fig. 3).

Matrix as a negative mould

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Figure 9: Finished enamel layer before removal of the wedge.

Figure 10: Finished enamel layer after removal of the wedge.

The shape of the tooth already has a largely natural appearance; the contact point is very good.

Figure 11: Due to drying out, the treated tooth 11 appears somewhat lighter than the contralateral tooth 21.

Figure 12: At the four-week check-up, both the shape and shade of the restored tooth 11 appear natural.

it is important to ensure that only the quantity of material actually required is used. Following light-curing of the last layer (Fig. 9) and removal of the matrix (Fig. 10), a largely natural shape of the build-up is already visible, including the transitions in the incisal edge region (Fig. 11). This makes finishing much quicker than is the case with overcontouring.

In addition, this procedure reproduces occlusal surfaces regularly and there is practically no excess material cervically either. Both the young patient and, in particular, his mother were very satisfied with the final result, including the shade (Fig. 12).

phenomenon in dental practices. If, as in the case described, there are no complications in terms of injuries to the bone or soft tissue and no root fractures, crown defects can then be treated quickly with a direct composite. As in the case of carious lesions, the shade and shape of the tooth need to be reproduced accurately for successful restoration results.

Depending on the specific characteristics of the tooth in question, both tasks can prove very demanding. In the case report illustrated, the desired result was achieved with a modified Hugo matrix technique combined with a relatively simple layering technique.5,8 The modification consisted in the use of an injectable temporary composite, which cannot be sculpted like temporary materials with higher viscosities .

In the case described, this was possible because the matrix

Discussion Trauma, especially of the upper anterior teeth, is a common

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already fitted very well and no pressure was required for additional anatomical shaping. The matrix lay in very close contact cervically and ensured that it was possible to build up the missing substance parallel to the approximal surface of the adjacent tooth. For the same reason, it was also possible to do without a palatal silicone index. If you want to make particularly certain, it is also possible to create a direct mock-up in the patient’s mouth or attempt to use an orthodontic model for a silicone index, for example.

Biocompatible restorative material Appropriate layering of two dentine shades and one enamel shade also made it possible to reproduce the missing substance in a shade very close to the natural one. The Ormocer® nanohybrid composite Admira Fusion was used, which contains no monomers associated with allergies, as in HEMA or BisGMA. Instead, both the matrix and the glass fillers are based on silicon oxide, which means that it is particularly biocompatible in comparison with other materials. Furthermore, it behaves like conventional, highquality nanohybrid composites in all other respects, including extremely low shrinkage.

Conclusion The result achieved with the described technique allowed the young patient to relax and smile again after the major

trauma of breaking his tooth. His mother seemed even more impressed than her son, as she had not expected such a speedy and aesthetically pleasing result.

References 1. Lam R. Epidemiology and outcomes of traumatic dental injuries: a review of the literature. Aust Dent J 2016;61 Suppl 1:4-20.

2. DGZMK. Fragebogen Frontzahntrauma; http://www.dgzmk.de / uploads/ media/ Frontzahntrauma _03_2016. pdf retrieved 21.12.2016. online resource, 2016.

3. Schmoeckel J, Eissa M, Splieth C. Frontzahntrauma – ein Überblick für die Praxis. Wir in der Praxis 2016:25-29.

4. DGMKG, DGZMK. Therapie des dentalen Traumas bleibender Zähne. S2k-Leitlinie, AWMF-Register 083-004, issued: 31.05.2015, valid until 30.05.2019, retrieved 13.12.2016.

5. Hugo B. Ästhetik mit Komposit. Grundlagen und Techniken.

Mit Beiträgen von Walter Denner, 2008.

6. Denner W. Ästhetik. Minimal-invasiv mit Komposit. wissen kompakt 2007:39-48.

7. Denner W. Direkte Kompositrestauration nach Frontzahntrauma. Quintessenz Team-Journal 2006;36.

8. Dietschi D. Layering concepts in anterior composite restorations. J Adhes Dent 2001;3:71-80.

VOL. 13, NO. 4 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION 9

CLINICAL

Class II Division 1 treatment using a two-phase approach – a case report Johan Christian Julyan1 and Marius Coetsee2

Abstract The improvement of facial aesthetics is one of the main reasons why patients with a Class II Division 1 malocclusion seek orthodontic treatment. There are various techniques available to treat Class II malocclusions, one of which is a two-phase approach that includes functional jaw orthopaedics as well as fixed orthodontic treatment. The following case report describes a young growing female patient with a severe Class II Division 1 malocclusion. The patient was treated using the functional removable appliance called the Twin Block, for growth modification and correction of her overjet and profile, in the first phase. Thereafter, a fixed pre-adjusted self-ligating Damon orthodontic appliance was utilized in the second phase, to ensure well aligned arches and improved aesthetics and function.

Key words: Orthodontic treatment, Class II Division 1, Two-phase treatment, Functional appliance, Twin Block, Selfligating brackets, Damon.

Introduction

1 Dr Johan Christian Julyan BChD (Pretoria), PDD (UWC), MSc (UWC) Tel: 074 136 3505 Fax: 021 975 5729 40 Wellington Road, Durbanville, Cape Town, 7550 E-mail: jcjulyan@gmail.com

2

Dr Marius Coetsee BChD (Stell), MChD (Medunsa) Tel: 021 557 1898 Fax: 021 557 6195 15 Nico Pentz Drive, Tableview, 7441 Email: marius@drcoetsee.co.za Corresponding author Dr. JC Julyan Tel: 021 975 7478 Cell: 074 136 3505 E-mail: jcjulyan@gmail.com

Class II Division 1 malocclusion cases are often complicated due to a skeletal discrepancy involving the maxilla and mandible. It can be as a result of a retrusive mandible and/or a protrusive maxilla.1 The most prevalent feature of this malocclusion in growing patients is mandibular retrusion.2 Treatment of skeletal Class II cases depends on growth, age, compliance and the severity of the malocclusion.3 There are various ways to treat an Angle Class II Division 1 malocclusion, with treatment options including both removable and fixed appliances. Removable appliances can be removed by the patient and require good compliance, whereas fixed appliances are bonded onto the teeth and do not require patient compliance for placement and removal. Removable treatment options include functional appliances and, more recently, clear aligners. There are more fixed options available and include fixed class II correctors and fixed orthodontic treatment in conjunction with inter-arch elastics and/or extractions and/or skeletal anchorage and/or orthognathic surgery, depending on the severity of the case.

In patients with psychosocial problems due to poor facial aesthetics and an enlarged overjet, a two-phase or early management approach can be followed, where the patient starts treatment in the late mixed dentition by making use of functional appliances, followed by the second phase where fixed appliances are used to finish the treatment in the permanent dentition. The use of a single phase or late treatment is advocated in cases where the patient has finished growing and treatment only commences in the permanent dentition with fixed appliance treatment.4 Various types of functional appliances exist and are designed to alter the activity of various muscle groups that influence the position and function of the mandible. By altering the vertical and sagittal position of the mandible, the muscle forces can result in orthodontic and orthopaedic changes in the dentition.5 The development of functional appliances originated in 1879 through Norman

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1a

1b

1c

Figure 1 (a-h): Pre-treatment photographs.

1d

1e

1f

1g

1h

Kingsley, who first introduced the bite-jumping appliance.

Kingsley’s appliance was a maxillary plate that acted by guiding the mandible forward during closure. In the early 1900’s, development in both the United States and Europe began with functional and fixed orthodontic techniques. The Monobloc of Robin, developed in 1902, was considered the forerunner of removable functional appliances. However, Andresen’s Activator, developed in the 1920s in Norway, was considered to be the first functional appliance to be widely accepted.6 Various functional appliances have been developed over the years mainly to correct Class II malocclusions by altering the soft tissues surrounding the teeth, causing a disruption in the occlusion and creating an inter-maxillary force.8 Functional appliances serve as a potentially successful treatment modality when used in growing patients diagnosed with a skeletal Class II Division 1 malocclusion due to a retrusive mandible.1 Adequate compliance by the patient is

necessary. Orofacial functional therapy can be used alone or in conjunction with other forms of therapy.7 The rational understanding that exists between environmental and genetic views in the context of the functional appliance and its potential to influence mandibular growth remains that there is a predetermined mandibular growth potential. The temporary acceleration of growth that is achieved with functional appliances does not have the potential to increase mandibular length or ramus height beyond that which is already genetically determined.9 Functional appliances can however result in dramatic Class II correction through dentoalveolar retroclination of the maxillary teeth and proclination of the mandibular teeth. They disclude the maxilla from the mandible and restrict maxillary growth. All these changes contribute to the establishment of a new occlusion while the patient is growing.8 Since William Clark originally developed the Twin Block appliance in 1982,7 it has been reported to be very effective

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2a

2b

Figure 2 (a-b): Pre-treatment extraoral photographs showing a hyperactive mentalis (a) and a lower lip trap (b).

in treating Class II Division 1 cases in growing patients.6 The Twin Block appliance is composed of acrylic removable plates containing acrylic bite blocks. These bite blocks connect at 70 degrees when the patient closes his/her mouth, while posturing the position of the mandible forward.10 The dramatic results often seen after wearing functional appliances are due to dentoalveolar movement. Maxillary teeth are tipped distally and mandibular teeth mesially. The appliances tend to restrict maxillary growth while establishing a new occlusal relationship in a patient that is actively growing.8 The perfect treatment timing of Class II malocclusions appears to be during or shortly after the start of the pubertal growth spurt.11 Detecting the pubertal growth spurt of mandibular growth is the best diagnostic tool for treatment planning in patients with a Class II malocclusion that is due to a mandibular deficiency. Of the various ways of determining the pubertal growth spurt of a patient, the Fishman’s hand wrist analysis and Cervical Vertebral maturation are the most popular.12 The bodies of the second, third and fourth cervical vertebrae can be analysed to determine growth of the patient and divided into six maturation stages. This method is preferred because it is performed on a lateral cephalogram - one of the diagnostic x-ray photos taken routinely for all orthodontic cases.13 Whilst the use of growth indicators remains controversial, the hand wrist analysis remains one of the most reliable methods due to its assessment of ossification events and not the use of single stages. No growth indicator has been found to have

a full diagnostic reliability in determining the pubertal growth spurt, but their use is still recommended for increasing efficiency of functional appliance treatment in Class II malocclusions.14 In some cases, functional treatment can achieve good results, but most often a second phase using fixed orthodontic appliances is necessary for treating any remaining discrepancies and to ensure proper interdigitation of the teeth in their new positions.

Case report A 10-year-old female patient (Figures 1 a-h) presented to a private practice with the main complaint that her front teeth stand out and she is made fun of at school. The patient requested treatment to improve her appearance. Nothing abnormal was detected in her medical history and she had undergone a previous dental consultation one year prior to her initial visit.

Upon clinical examination the patient presented with a Class II Division 1 malocclusion. Extra-oral examination revealed that the patient was brachycephalic with a severely convex profile and a posterior facial divergence. She had good facial symmetry and her maxillary midline was coincident with her midsagittal plane. She presented with incompetent lips and a hyperactive mentalis muscle with a lower lip trap.

Intra-oral examination revealed that the patient was in her transitional dentition stage. She had healthy gingiva with a swollen papilla between teeth 11 and 21and had an Angle Class II molar classification bilaterally. In occlusion she had

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an overjet of 15 mm and an overbite of 9/10 (90%). There was spacing of the maxillary incisor teeth and mild crowding of the mandibular incisors.

The functional examination revealed that the patient had a history of thumb sucking and mouth breathing habits. Her incompetent lips and enlarged overjet resulted in a lower lip trap and hyperactive mentalis activity (Figures 2 a and b).

Radiographic findings The radiographic analysis of the patient’s initial orthopantomogram showed a second transitional stage with the canines and premolars erupting, with no other abnormalities (Figure 3).

The cephalometric analysis (Table 1), conducted before treatment, revealed a Class II skeletal relationship.

Figures 4 (a and b), show the pre-treatment cephalogram and the cephalometric analysis done with Dolphin® orthodontic software.

Diagnosis Soft tissue The patient presented brachycephalic with a severely convex profile, posterior divergence, lower lip wedge and a Class II lip relationship.

Skeletal Class II skeletal malocclusion [Steiner - ANB (8.6°) and WITS (7.6 mm)] with a retrognathic mandible [SNB (71.0°) and Facial angle (85.4°)] and a normal growth pattern.

4a

Figure 3: Pre-treatment orthopantomogram

Dental Angle Class II Division 1 with maxillary incisors proclined and protrusive and mandibular incisors retrusive. An overbite of 9/10 and an Overjet of 15mm due to the proclined maxillary incisors and retruded mandible position.

Treatment objectives The treatment objectives of the first phase of treatment in this case were, primarily, to reduce the enlarged overjet and improve the facial appearance and self-confidence of the patient. A further objective was to improve the deep bite and achieve a Class I molar and canine relationship. The final objective was the normalising of the musculature by eliminating the lower lip trap and hyperactive mentalis muscle.

The second phase objective was to resolve any residual crowding, ensure good interdigitation, settle the teeth in their new positions and ensure a functionally acceptable result.

4b

Figure 4: (a) Pre-treatment cephalogram and (b) cephalometric analysis.

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Table 1. Pre-treatment cephalometric analysis Cephalometric values

Normal

Pre - Treatment

SNA (˚)

82.0

79.6

SNB (˚)

80.9

71.0

ANB (˚)

1.6

8.6

WITS (mm)

-1.0

7.6

Interincisal angle (˚)

130.0

111.7

U1 – SN (˚)

102.4

114.6

4.3

6.7

22.8

35.0

4.0

2.9

L1 – NB (˚)

25.3

24.7

FMIA (L1 – FH) (˚)

63.5

60.9

IMPA (L1 – MP) (˚)

95.0

96.1

Lower lip to E-Plane (mm)

-2.0

-3.1

Upper lip to E-plane (mm)

-3.3

1.7

Soft tissue convexity (˚)

135.7

129.6

Convexity (A-NPo) (mm)

1.5

7.6

102.0

105.9

Facial angle (˚)

87.2

85.4

Upper lip thickness at A-point (mm)

17.0

10.9

Upper lip thickness at Vermilion border (mm)

13.1

9.4

U1 – NA (mm) U1 – NA (˚) L1 – NB (mm)

Nasolabial angle (˚)

Treatment options There are various ways to treat an Angle Class II Division 1 malocclusion. The treatment options include both removable and fixed options and can be done in one or two phases.

In one phase treatment the patient is treated once all permanent teeth have erupted and makes use of fixed orthodontic treatment in conjunction with inter-arch elastics, extractions and sometimes fixed functional correctors. In two phase treatment a removable functional appliance is placed in the mixed dentition for growth modification and followed with fixed treatment as a second phase.

The treatment options for this case can be categorised as either growth modification, camouflage or surgical correction.

- Growth modification by making use of functional appliances as a first phase and fixed orthodontic treatment

in the second phase if necessary.

- Camouflage treatment which include fixed orthodontic treatment in conjunction with inter-arch elastics and/or extractions and/or skeletal anchorage.

- Surgical correction which includes a combination of fixed orthodontic treatment and orthognathic surgery that can only be done after the age of 18.

Treatment plan The two-phase treatment - Growth modification (Twin Block) and fixed orthodontic treatment. The following steps were followed for the chosen treatment plan: First phase: 1. Complete all necessary basic restorative dentistry.

2. Scale and polish and oral hygiene instructions.

3. Take impressions for the fabrication of the functional removable appliance (Twin Block).

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5a

5b

5c Figure 5 (a-c): Twin Block in place.

Figure 6: T4K Orthodontic trainer appliance.

4. Make use of the removable appliance to improve the overjet, expand the maxillary arch and obtain a Class I molar and canine relationship.

The amount of soft tissue strain is normal after initial Twin Block placement in a severe Class II case with a severe overjet. The strain improves with the dentoalveolar retrusion of the maxillary and protrusion of the mandibular anterior teeth throughout treatment.

The lower appliance incorporated a labial bow with acrylic coverage to inhibit the excessive proclination of the lower incisors, (Figure 5a and b). The patient was instructed to wear the Twin Block at all times and to only remove it in order to clean it. A mid-palatal expansion screw was incorporated in the maxillary appliance and the patient was instructed to perform a ¼ turn twice per week. The maxillary arch in most Class II Division 1 cases is constricted and requires expansion. This expansion is also necessary to ensure that bilateral posterior crossbites do not develop with the forward positioning of the mandible. The patient struggled with the Twin Block appliance at first but showed excellent compliance and persisted in wearing the appliance for the rest of the first phase of treatment.

The total treatment time of the Twin Block was 12 months.

After the Twin Block treatment, the patient was given a T4KTM (Trainer for Kids, Myofunctional Research Co, Australia)

Second phase: 5. Fixed orthodontic treatment using the Damon self-ligating orthodontic system.

6. The fixed orthodontic treatment used to resolve any residual crowding and to improve interdigitation of the permanent teeth in order for them to settle in the new Class I position.

7. Retention – Permanent fixed mandibular retainer and removable maxillary and mandibular clear retainers to be worn at night.

First Phase – Twin Block The initial placement of the Twin Block with the posturing of the mandible showed early improvement of the patient’s profile and appearance and motivated her to wear it. There was soft tissue strain present with the large amount of posturing necessary to position the mandible into a better position when the appliance was first placed (Figure 5 c).

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Table 2. Cephalometric analysis after first phase of treatment Cephalometric values

Normal

Pre Treatment

SNA (˚)

82.0

79.6

78.8

SNB (˚)

80.9

71.0

74.0

ANB (˚)

1.6

8.6

4.8

WITS (mm)

-1.0

7.6

0.2

Interincisal angle (˚)

130.0

111.7

120.3

U1 – SN (˚)

102.4

114.6

95.8

4.3

6.7

3.3

22.8

35.0

17.0

4.0

2.9

7.1

L1 – NB (˚)

25.3

24.7

37.8

FMIA (L1 – FH) (˚)

63.5

60.9

48.9

IMPA (L1 – MP) (˚)

95.0

96.1

105.0

Lower lip to E-Plane (mm)

-2.0

-3.1

-0.4

Upper lip to E-plane (mm)

-3.3

1.7

-1.9

Soft tissue convexity (˚)

135.7

129.6

132.9

Convexity (A-NPo) (mm)

1.5

7.6

4.3

102.0

105.9

116.4

Facial angle (˚)

87.2

85.4

86.5

Upper lip thickness at A-point (mm)

17.0

10.9

12.9

Upper lip thickness at Vermilion border (mm)

13.1

9.4

9.9

U1 – NA (mm) U1 – NA (˚) L1 – NB (mm)

Nasolabial angle (˚)

orthodontic trainer appliance (Figure 6) to sleep with until all permanent teeth were erupted and in occlusion. The T4K appliance is a polyurethane pre-fabricated functional appliance.15 The decision to use the T4K appliance was to promote uninhibited eruption of the permanent posterior teeth after the Twin Block phase. The absence of acrylic and retentive clasps was the motivating factor for using the appliance. The T4K, the author’s preference, is not as rigid as the Twin Block and allows further growth in an anteroposterior and transverse direction. Another effective technique is to allow the patient to continue to wear the Twin Block appliance at night with a modification of the upper acrylic inclined blocks to allow for the eruption of the posterior teeth. A further option is to construct a maxillary Hawley appliance with an anterior inclined plane, also to be worn at night until all posterior teeth are in occlusion.

After the first phase of treatment with the Twin Block, the

After phase one (Twin Block)

following cephalometric values were noted (Table 2). Figures 7a and b show the cephalogram and the cephalometric analysis done directly after the Twin Block treatment. The clinical photos taken directly afterwards are shown in Figures 8 a-h. At this stage in the treatment the patient no longer had to posture the mandible into a more favourable position.

Each time the patient closed her mouth, the mandible was in the same position with very little lip strain.

The lateral open bites seen after the first phase of treatment occurred as a result of the restraint of eruption of the posterior teeth due to the occlusal blocks and unimpeded incisal eruption and vertical growth. It is indicative of the patient’s compliance in wearing the appliance. Once the overjet is reduced the upper acrylic occlusal blocks are trimmed for the lower first molars to erupt and close the open bites. While the lateral open bites close spontaneously, acrylic trimming is advocated to limit the chance of relapse and to ensure

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7a

7b

Figure 7: (a) Cephalogram after Twin Block phase and (b) cephalometric analysis after Twin Block phase.

good occlusion post treatment.16 The changes seen after treatment are the result of the posturing of the mandible forward together with dentoalveolar changes that occurred.

During the retention period after the Twin Block treatment the posterior occlusion settled in the new position. Although the molars and canines were in a Class I position, there was still mild dental crowding present (Figures 9 a-h).

There was a lack of sufficient transverse expansion with the Twin Block after the first phase of treatment. The required expansion was one of the objectives of the second phase of the treatment and was achieved through use of the broad Damon Copper Nickel Titanium archwires. Resolving the residual crowding, improving the interdigitation of the teeth in their new positions and ensuring a functionally acceptable

Table 3. Archwire sequence used for second phase of treatment Maxilla

Mandible

0.014 CuNiTi

0.014 CuNiTi

0.014 x 0.025 CuNiTi

0.018 CuNiTi

0.014 x 0.025 CuNiTi

0.014 x 0.025 CuNiTi

0.018 x 0.025 CuNiTi

0.018 x 0.025 CuNiTi

0.016 x 0.025 SS

0.019 x 0.025 TMA

result were the other objectives of the second phase of treatment. This was achieved using the Damon self-ligating fixed orthodontic appliance. Treatment time for the second phase with fixed orthodontic treatment was 12 months.

Second Phase – Fixed appliance treatment The Damon self-ligating pre-adjusted orthodontic system was used to conduct the second phase of treatment (Figures 10 a-e). Alignment was done using Copper Nickel Titanium (CuNiTi) archwires and the case was finished on stainless steel (SS) and titanium molybdenum alloy (TMA) wires. The archwire sequence that was used is shown in Table 3 .

The final archwire for the lower arch was a 0.019 x 0.025 TMA. This archwire was used so that a reverse curve of Spee could be bent in order to further open the bite, plus its increased flexibility has better patient tolerance, making it easier for the clinician to work with.

The final archwire for the upper arch was a 0.016 x 0.025 SS. Conventionally the final wire would have been a 0.019 x 0.025 SS, but the decision was made after clinical evaluation of the maxillary anterior teeth that the final archwire of 0.016 x 0.025 SS would be adequate. A further increase in torque would have resulted in an even smaller interincisal angle with the already proclined lower incisors. Clinically, the torque of the maxillary incisors was evaluated and thought to be adequate. No inter-arch Class II elastics were used during the second/fixed orthodontic phase of treatment. The patient had a stable Class I bite from

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8a

8b

8c

Figure 8 (a-h): Intra-oral photos directly after Twin Block phase.

8d

8e

8f

8g

the end of the first phase throughout the rest of the treatment.

This proved that the correction seen after the first phase was not due to posturing and that a new occlusal relationship had been established that was stable and reproducible without any strain. The only elastics that were used were for settling the teeth in their new positions (Ostrich 2 Oz, 19.1mm – ORMCO). This was done for the last two weeks prior to the removal of the braces.

Treatment outcome The treatment resulted in well aligned arches with Class I molar and canine relationships (Figures 11 a-h). The upper midline corresponded to the patient’s midsagittal plane and the teeth were settled in the new occlusion. The soft tissue profile improved and the lip trap and hyperactive mentalis that the patient presented with initially was resolved.

8h

Superimposition Superimposition was done of the pre- and post-treatment cephalometric analyses (Figure 12). The images were superimposed on the cranial base, maxilla and mandible.

The initial cephalometric tracing is illustrated in black and the final tracing in green.

Cranial base superimposition: Shows the correction of the molar relationship from Class II to Class I. It also reveals the reduction in overjet and overbite as well as the improvement of the lip relationships from Class II to Class I. An increase in lower facial height and mesial movement of the mandibular first permanent molar into a Class I relationship is also shown.

Maxilla superimposition: Represents how the maxillary incisors retroclined throughout treatment, as well as the inferior movement as the maxillary first permanent molars with

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9a

9b

9c

Figure 9 (a-h): Intraoral photos after the first phase of treatment with all permanent teeth erupted and in occlusion.

9d

9e

9f

9g

9h

the over-eruption into the space available and opening of the bite. The eruption of the maxillary molars most likely occurred when the Twin Block was removed and the T4K appliance placed, since only the maxillary acrylic block was trimmed during the first phase of treatment with the Twin Block.

Mandible superimposition: Represents the proclination of the mandibular incisors that occurred during treatment as well as the superior movement of the mandibular first permanent molars during treatment. Mandibular changes can be seen in the vertical and horizontal direction.

The superimpositions show that the treatment objectives set out for this patient were achieved. These included a reduced overjet, deep bite correction, Class I molar and canine relationships, elimination of the lower lip trap and improved facial appearance.

Comparison of Initial and final orthodontic study models A comparison was made of the pre-treatment and posttreatment orthodontic study models to show the change that occurred from all the different views (Figures 13 a-j).

Frontal view: Vertical and transverse correction showing deep bite correction and improved inclination and position of the posterior segments without any crossbites present (Figures 13 a and b).

Lateral views: Improvement in the anteroposterior dimension with a decreased overjet and correction of the Class II molar and canine relationships to Class I (Figures 13 c-f).

Maxillary and mandibular occlusal views: Well aligned arches without any residual spaces or rotations (Figures 13 g-j).

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Cephalometric values Table 4 shows the values of the cephalometric analyses from the start to the completion of treatment.

Discussion Class II Division 1 treatment aims to correct the molar and canine relationship to Class I, reduce the overjet, improve the deep bite and ensure a functionally correct result with teeth settled in their new positions without any adverse effects on the temporomandibular joint.

Treatment of Class II Division 1 malocclusions should also be aimed at solving the dentoskeletal disharmony in order to obtain favourable facial aesthetics.17 The use of a twophase treatment approach can successfully treat growing patients and can drastically improve both function and aesthetics, ultimately resulting in improved self-confidence.

The first phase requires compliance from the patient and is carried out using a removable functional appliance. The second phase is done using a fixed orthodontic appliance system. There is consensus that removable functional appliances can lead to improved facial appearance in Class II cases.18 Functional appliances act by eliminating oral dysfunctions, re-establishing muscular balance and correcting maxillary incisor protrusion.19 Functional appliances can result in dramatic Class II correction through dentoalveolar retroclination of the maxillary teeth and proclination of the

10a

10c

mandibular teeth. They disclude the maxilla from the mandible and restrict maxillary growth. All these changes contribute to the establishment of a new occlusion while the patient is growing.8 The Twin Block, developed by William Clark is an example of a removable functional appliance. Twin Block therapy is widely accepted as a better alternative to the earlier bulky monobloc appliances when treating Class II Division 1 cases. The Twin Block appliance has a high rate of adaptability, acceptability, efficiency, versatility and the ease of advancing the mandible incrementally without having to change the appliance has made it the popular choice for correcting Class II malocclusions.20 Early treatment with orthopaedic appliances is successful in 80% of cases with malocclusion and the remaining 20% require the use of fixed appliances.21 Successful treatment of Class II Division 1 cases can prevent 1) possible trauma to maxillary incisors, 2) Tempero-mandibular joint dysfunction and 3) poor psychosocial adaptation.22 There still exists a lack of evidence that functional appliances can cause a significant effect on mandibular growth long term. Despite this lack of evidence, the use of functional appliances has been proven to be very effective for reducing the overjet in growing patients with Class II malocclusions. Functional appliances make use of dentoalveolar movement, altered soft tissue environment and

10b

10d

10e

Figure 10 (a-e): Damon fixed orthodontic appliance treatment.

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11a

11b

11c

Figure 11 (a-h): Post-treatment photographs.

11d

11e

11f

11g

11h

the greater growth potential of the mandible to successfully decrease the overjet in growing patients. Functional appliances require patient compliance and will therefore not be successful in all cases. Patient selection is of utmost importance to ensure successful treatment.8 Class II malocclusion correction should occur when the likelihood of the pubertal growth spurt is high.13 It is important to consider that in mild to moderate skeletal Class II Division 1 cases, where active growth is complete, it is not possible to undertake growth modification treatment. The underlying skeletal discrepancy of some severe cases can be camouflaged by orthodontic treatment in conjunction with extractions. Adult patients with very severe discrepancies, should undergo orthodontic treatment in conjunction with orthognathic surgery.23

Figure 12: Cephalometric tracing superimposition in black (pretreatment) and green (post-treatment).

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13a

13b

13c

13d

13e

13f

13g

13h

13i

13j Figure 13 (a-j): Pre- and post-treatment orthodontic study models.

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Table 4: Cephalometric values before and after treatment Cephalometric values

Normal

Pre - Treatment

SNA (˚)

82.0

79.6

77.7

SNB (˚)

80.9

71.0

72.6

ANB (˚)

1.6

8.6

5.2

WITS (mm)

-1.0

7.6

1.3

Interincisal angle (˚)

130.0

111.7

124.9

U1 – SN (˚)

102.4

114.6

93.2

4.3

6.7

2.9

22.8

35.0

15.5

4.0

2.9

6.9

L1 – NB (˚)

25.3

24.7

34.5

FMIA (L1 – FH) (˚)

63.5

60.9

53.1

IMPA (L1 – MP) (˚)

95.0

96.1

103.0

Lower lip to E-Plane (mm)

-2.0

-3.1

-0.9

Upper lip to E-plane (mm)

-3.3

1.7

-2.5

Soft tissue convexity (˚)

135.7

129.6

126.2

Convexity (A-NPo) (mm)

1.5

7.6

5.2

102.0

105.9

119.0

Facial angle (˚)

87.2

85.4

86.9

Upper lip thickness at A-point (mm)

17.0

10.9

14.6

Upper lip thickness at Vermilion border (mm)

13.1

9.4

11.2

U1 – NA (mm) U1 – NA (˚) L1 – NB (mm)

Nasolabial angle (˚)

Post treatment

Conclusion

References

• The two-phase approach will not always be successful and unfortunately its success is not readily predictable.

• A successful two-phase approach in Class II Division 1 cases has the potential to prevent the removal of bicuspids to treat the malocclusion.

• The improvement in facial aesthetics caused by the functional treatment significantly improved the patient’s selfconfidence even if it was only dentoalveolar movement that occurred.

• The success of this case would not have been possible without the compliance of the patient in the first phase of treatment.

• If a one phase fixed orthodontic treatment was done for this patient she would have had to wait another 2 years for all her permanent teeth to erupt before any difference could have been made to her facial aesthetics and confidence.

1. Pachori Y, Navlani M, Gaur T, Bhatnagar S. Treatment of skeletal class II division 1 malocclusion with mandibular deficiency using Functional appliances in growing individuals. Journal of Indian Society of Pedodontics and Preventive Dentistry 2012; 30(1): 5665.

2. McNamara J. Component of Class II malocclusion in children 8-10 years of age. Angle Orthodontist 1981; 51:177-202.

3. Tulloch JF, Proffit WR, Phillips C. Influences on the outcome of early treatment for Class II malocclusion. American Journal of Orthodontics and Dentofacial Orthopedics 1997; 111:533-542.

4. Gianelly AA. One-phase versus two-phase treatment.

American Journal of Orthodontics and Dentofacial Orthopedics 1995; 108 (5): 556-559.

5. Bishara SE, Ziaja RR. Functional appliances: A review.

American Journal of Orthodontics and Dentofacial Orthopedics 1989; 95 (3): 250-258.

6. Wahl N. Orthodontics in 3 millennia. Chapter 9: Functional appliances to midcentury. American Journal of Orthodontics and Dentofacial Orthopedics 2006; 129 (6): 829-833.

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14a

14b Figure 14 (a and b): Cephalograms before treatment (a) and after treatment (b).

7. Homem MA, Viera-Andrade RG, Falci SGM, Ramos-Jorge ML, Marques LS. Effectiveness of orofacial Functional therapy in orthodontic patients: A systematic review. Dental Press Journal of Orthodontics 2014; 19(4): 94-99.

8. DiBiase AT, Cobourne MT, Lee RT. The use of functional appliances in contemporary orthodontic practice. British Dental Journal 2015; 218(3): 123-128.

9. Lysle EJ. Functional Appliances: A mortage on mandibular position. Australian Orthodontic Journal 1996; 14(3): 154 – 157.

10. Toth LR, McNamara JA. Treatment effects produced by the twin-Block appliance and the FR-2 appliance of Frankel compared with an untreated class II sample. American Journal of Orthodontics and Dentofacial Orthopedics 1999; 116: 597-609.

11. Baccetti T, Franchi L, Toth LR. Treatment timing for Twin-Block therapy. American Journal of Orthodontics and Dentofacial Orthopedics 2000; 118: 159-170.

12. Baccetti T, Franchi L, McNamara JA. An improved version of the cervical vertebral maturation (CVM) method for the assessment of mandibular growth. Angle Orthodontist 2002; 72: 316-323.

13. Baccetti T, Franchi L, McNamara JA. The cervical vertebral maturation (CVM) method for the assessment of optimal treatment timing in dentofacial orthopaedics. Semin Orthod 2005; 11: 119-129.

14. Perinetti G, Contardo G. Reliability of Growth Indicators and Efficiency of Functional Treatment for Skeletal Class II Malocclusion: Current Evidence and Controversies. BioMed Research International 2017: 1-19.

15. Quadrelli C, Gheorgiu M, Marcheti C, Ghiglione V. Early

myofunctional approach to skeletal Class II. Mondo Orthodontico 2002: 109-122.

16. Clark W. Design and management of Twin Blocks: reflections after 30 years of clinical use. Journal of Orthodontics 2010; 37 (3): 209-216.

17. Quintao C, Brunharo HVP, Menezes RC, Almeida MAO. Soft tissue facial profile changes following Functional appliance therapy. European Journal of Orthodontics 2006; 28: 35-41.

18. Pancherz H, Anehus-Pancherz M. Facial profile changes during and after Herbst appliance treatment. European Journal of Orthodontics 1994; 16: 275-286.

19. Tallgren A, Christiansen RL, Ash M Jr, Miller RL. Effects of a Functional appliance on orofacial muscle activity and structures.

Angle Orthodontist 1998; 68: 249-258.

20. Daragiu D, Ghergic DL. Clinical effects of removable Functional twin Block appliance in the treatment of Class II/1 malocclusion. Vasile Goldis University Press 2012; 22(4): 471-476.

21. Rondeau BH. Class II malocclusion in mixed dentition. Journal of Clinical and Pediatric Dentistry 1994; 19:1-11.

22. Azevedo A, Janson G, Henriques J, De Freitas M. Evaluation of asymmetries between subjects with class II subdivision and apparent facial asymmetry and those with normal occlusions.

American Journal of Orthodontics and Dentofacial Orthopedics 2006; 129: 376-383.

23. Hsieh TJ, Pinskaya Y, Roberts WE. Assessment of orthodontic treatment outcomes: early treatment versus late treatment. Angle Orthodontist 2005; 75: 162-170.

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CLINICAL

Removal of fractured endodontic instruments: A report of two cases Casper H Jonker1 and Carel (Boela) van der Merwe2

Abstract The separation of an endodontic instrument within the root canal system can be one of the most stressful and unpleasant situations the clinician can be confronted with. These fractures often occur due to incorrect use of instruments. The clinician is confronted with a few options when considering this situation. These options can include leaving the fragment where the fracture occurred and incorporating the fragment to form part of the final obturation or removal from the root canal. Once the decision is made to remove the fractured instrument, the clinician must realize that the procedure can be one of the most difficult treatments to attempt. According to the literature, there is no standardized method to follow when attempting to remove fractured instruments. The presented cases illustrate effective techniques to remove fractured endodontic instruments from the root canal system. Two cases are discussed where fractured instruments are removed using various manual instruments, ultrasonics, chemicals and the Dental Operating Microscope (DOM). Satisfactory endodontic outcomes were achieved and the fractured instruments were successfully removed without causing iatrogenic damage to the remaining tooth structure.

Introduction

1 Casper H Jonker BChD, Dip.Odont, Msc. Module of Endodontics, Department of Operative Dentistry, School of Oral Health Sciences, Sefako Makgatho Health Sciences University, Gauteng, South Africa

2

Carel (Boela) van der Merwe B.Ch.D, BSc Hons, Dip Odont, MSc. Private practice, Dental Welness Dimensions, Bryanston Corresponding Author: Dr. CH Jonker, 012 521 4813, casper.jonker@smu.ac.za

Root canal treatments are attempted with the knowledge that certain unforeseen accidents can occur during any part of the treatment. These accidents can include fracture of instruments, perforation of the root on different levels and the formation of ledges. Once a tooth is exposed to procedural accidents and unforeseen complications, there is an increased risk of failure of the endodontic treatment and reduction of long term prognosis.1,2,3 The complete treatment can be jeopardized from the cleaning and shaping sequence to the ultimate obturation and 3D sealing of the root canal system.2,3 The reason why a root canal treatment is performed is to eliminate microorganisms within the root canal system, removal of necrotic or infected pulp tissues and complete sealing of the root canal spaces.1 The separation of an endodontic instrument within the root canal system can be one of the most stressful and unpleasant situations the clinician can be confronted with.

These fractures often occur due to incorrect use of instruments. Operators can utilize incorrect movements during cleaning and shaping or use deformed instruments pushing them beyond their ability to absorb the workload.4,5 Once an instrument fractures, a detailed approach should be followed to assess the possibility of removal. The clinician should be thoroughly aware of the complicating factors when attempting the removal.

These factors may include the unique anatomy of the root canal system, the availability of materials, instruments and devices to dislodge and remove separated instruments, the clinician’s experience and ability and finally the location, size, position and diameter of the fractured portion.5,6 The treating clinician is confronted with a few options when considering an approach. These options are leaving the fragment where the fracture occurred and incorporating the fragment to form part of the final obturation or attempt removal from the root canal.7 There is also an alternative technique which can be considered namely “bypass” of the separated fragment. Although a tedious exercise, creating space and inserting a small manual file between the fragment and the root

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1

2

Figure 1: Pre-operative radiograph revealing a large fragment of a fractured instrument in the mandibular second incisor.

Figure 2: Magnified image of the modified head of the size 3 Gates Glidden bur used to create the staging platform.

canal may lead to full working length negotiation.

Occasionally the fragment can be loosened and removed during bypassing, but often the fragment remain in situ and end up forming an integrated part of the final obturation.7 Once the decision is made to remove the fractured instrument, the clinician must realize that the procedure can be one of the most difficult treatments to attempt.8 According to the literature, there is no standardized method to follow when attempting to remove fractured instruments.9 The importance of proper vision, illumination and magnification cannot be emphasized enough when attempting retrieval.10 The Dental Operating Microscope (DOM) can create direct visualization of the fractured instrument fragment deep in root canals where normal vision is inadequate.11 The following case presentations aim to describe an effective approach to remove a fractured instrument using documented techniques and a combination of instruments and equipment including manual fine ultrasonic tips, small sized manual files and the DOM.

Case Report 1 A 31-year-old female patient with uncomplicated medical history reported with a referral letter from a nearby practice requesting removal of a fractured instrument from her mandibular second incisor. The clinician fractured an instrument during cleaning and shaping and incorporated the fragment into the final obturation. The patient developed discomfort after a period of time and after discussion with the treating clinician, the patient was referred for removal of the fragment. A pre-operative radiograph was taken and it

was noted that a large portion of an endodontic instrument fractured inside the root canal with extrusion beyond the apical foramen (Figure 1).

Possible complications were explained before any treatment was carried out. The tooth was anaesthetized and the restoration removed to expose the obturation material.

Gutta-percha was removed to the level of the fractured instrument using a combination of solvents (Chloroform BP, Medicolab, Johannesburg, South Africa) and K-files. The Dental Operating Microscope (DOM) (Carl Zeiss, Oberkochen, Germany) was used to obtain straight line access and visualize the fractured instrument. A staging platform was created by altering a number 3 Gates Glidden bur (Dentsply Sirona Endodontics, Ballaigues, Switzerland) (Figure 2) to the level of the coronal portion of the fragment.

The root canal space was flooded with 17% liquid EDTA (Vista Dental Products, Racine, USA) and activated using the ultrasonic E7 tip (NSK, Kanuma Tochigi, Japan) in an effort to remove debris and inorganic matter and improve visualization of the fragment. The tip was placed on the coronal part of the fractured instrument and activated on a low setting of 3 on the ultrasonic unit (NSK, Kanuma Tochigi, Japan). This sequence was repeated 4 times to ensure proper removal of debris in the coronal region of the fractured instrument. The canal was dried and a 0.6 C+ file (Dentsply Sirona Endodontics, Ballaigues, Switzerland) (Figure 3a) was introduced in a gentle pecking motion with slight apical pressure, ultrasonic activation and viscous 15 % EDTA paste (Glyde, Dentsply Sirona Endodontics, Ballaigues, Switzerland) as lubricating agent. Ultrasonic energy was

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3a

3b Figure 3a: The 0.6 C+file used with viscous 15 % EDTA paste to locate a portal of entry for the size 0.6 K-file to follow.

Figure 3b: The 0.6 K-file used in a watch-winding motion with viscous 15% EDTA paste after the initial penetration of the 0.6 C+ file.

transferred to the small hand instruments by placing an ultrasonic tip against the shaft of the file. Once slight apical progression was noted, the 0.6 C+ file was removed and a 0.6 K-file (Dentsply Sirona Endodontics, Ballaigues, Switzerland) (Figure 3b and Figure 3c) was introduced and used in a similar technique to allow apical progression.

A simultaneous action of gentle pulling, sideways pressure and ultrasonic vibration transferred from the small hand instruments to the fragment was used in an effort to loosen and move the segment in a coronal direction. The above sequence was repeated until full working length was reached with the size 0.6 K-file (Figure 4 and Figure 5).

Once movement of the fractured instrument could be observed under magnification, the engaged K-file was

3c Figure Figure Figure Figure Figure

4

tightened by gently rotating the file in a clockwise direction until sufficient resistance was created and the file was tightly engaged around the segment. A gentle pulling motion with lateral pressure was used in an effort to remove the fractured instrument. The engagement created sufficient resistance to lift the fractured instrument coronally and safely remove from the root canal system (Figure 6 and Figure 7).

Case Report 2 A patient with uncomplicated medical history was referred for the removal of fractured instruments in a mandibular second molar. The pre-operative radiograph revealed a fractured instrument in the shape of a Lentulo spiral filler in the disto-buccal canal (joining in the apical third with the

5

6

7

3c: The 0.6 K-file engaged in the pathway created by the 0.6 C+file.

4: The gentle pulling action on the 0.6 K-file with ultrasonic activation moving the fragment in a coronal direction.

5: Full working length reached with the 0.6 K-file and fragment moving coronally.

6: Fractured instrument removed with limited amount of destruction of tooth structure.

7: A large segment of a fractured instrument viewed under magnification after removal from the root canal.

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disto-lingual canal) as well as a fractured endodontic instrument in the mesio-buccal canal (Figure 8). Peri-apical radiolucencies were noted on both roots. The tooth was obturated by the referring clinician 4 years ago incorporating the fractured instruments, but the patient developed discomfort over time. After possible complications of the suggested treatment were explained, the tooth was anaesthetized and rubber dam isolation was achieved. A number 1 Gates Glidden bur (Dentsply Sirona Endodontics, Ballaigues, Switzerland) with a flooded root canal space with 90% chloroform (Chloroform BP, Medicolab, Johannesburg, South Africa) was used to soften the guttapercha. A number 0.6 C+file (Dentsply Sirona Endodontics) was used to create a pathway to the level of the fractured instrument and softened coronal gutta-percha was removed (Figure 9).

A similar technique as described in case report 1 was used to bypass and remove the fragment in the mesio-buccal root. In the disto-buccal root a similar technique was followed to scout for space around or through the fractured spiral filler and reach full working length. The 0.6 C+ file sequence was followed by a pre-curved K-file sequence through the fractured fragment untill a size 30 K-file (Dentsply Sirona Endodontics, Ballaigues, Switzerland) was reached to full working length. Glyde 15% EDTA paste was used as lubricating agent and in between each file sequence, the root canal space was irrigated using 6% sodium hypochlorite (Vista Dental Products, Racine, USA), patency confirmed with

11

12

Figure 11: Working length determination and engagement of the fractured spiral filler with a size 30 Hedstrom file.

Figure 12: Completed obturation with System B continuous wave technique and Obtura III.

8

9

10 Figure 8: Pre-operative radiograph revealed a fractured spiral filler in the disto-buccal canal as well as a fractured endodontic instrument in the mesio-buccal canal.

Figure 9: Obturation material removed and fractured fragments exposed using the number 1 altered Gates Glidden bur.

Figure 10: A new size 30 Hedstrom file used to engage the fragment after the initial path of insertion was created to a size 30 K-file.

a size 10 K-file (Dentsply Sirona Endodontics, Ballaigues, Switzerland), recapitulation performed and the root canal re-irrigated to remove debris. A new size 30 Hedstrom file (Dentsply Sirona Endodontics, Ballaigues, Switzerland) (Figure 10) was pre-curved and gentle apical pressure was applied in an effort to engage the fragment (Figure 11).

A Steiglitz fractured instrument retrieval forceps (Tinman Dental, Redding, USA) was used to lift the fragment coronally using the remaining tooth structure as support. Shaping of all canals was completed using the ProTaper Universal system (Dentsply Sirona Endodontics, Ballaigues, Switzerland) and all root canals were irrigated in a similar technique as described above. The canals were dried using large paper points and a final rinse with 17% liquid EDTA (Vista Dental Products, Racine, USA) was performed in an effort to remove the smear layer. Obturation was completed using the continuous wave technique with System B (Kerr Dental, Orange, USA) and Obtura III (Obtura Spartan Endodontics, Algonquin, USA) (Figure 12).

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Discussion To encounter instrument fracture in clinical practice is not uncommon. In a survey that was conducted in the United Kingdom where clinicians were ask to report on the incidence of instrument fracture during endodontic treatment, 89% reported that they have experienced the unfortunate event.12 Several factors can attribute towards instrument failure. These factors can include the creation of inadequate access into the root canal system, anatomical challenges and extreme root curvatures, multiple treatments of the same instrument and the skill set and experience of the treating clinician.13,14 VarelaPatiĂąo et al.15 also described the importance of glide path preparation to reduce the fracture of endodontic instruments.

These authors found that fewer fractures occurred when using rotary instruments when a wide and smooth-walled glide path was created and the canal was pre-flared before the introduction of rotary files. In the presented cases, it can be

speculated that inadequate access, lack of proper glide path and increased torsional stress could have attributed to instrument fracture(s), although other factors could also have played a role. Yum et al.16 have concluded that torsional stress and torsional failure are more prevalent in straight canals. Further, the use of spiral fillers must be used with great care in endodontics as they require experience and good tactile sensation to avoid instrument fracture. The instrument possesses a very low fracture resistance to torsional fatigue and any engagement to the root canal wall can result in instrument separation as observed in case report 2.

The use of the Dental Operating Microscope in endodontics has been advocated by numerous authors in the literature and provided a breakthrough in endodontic treatments. This invaluable piece of equipment has been advocated for the treatment of perforations, removal of fractured instruments, location of orifices and other

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applications in endodontics.17,18,19 Once the decision was made for the removal of a fractured instrument in the presented case, magnification and optimal illumination played a vital role. The creation of the staging platform and use of ultrasonics required proper illumination and magnification and avoid further iatrogenic damage. Further, proper vision under magnification allowed the location of the space between the fractured instrument flutes and created a pathway for small hand instruments (0.6 C+ file and 0.6 K-file). It can be speculated that without proper vision the fractured segment could not have been predictably bypassed or removed.

One of the treatment options to consider in a case presenting with a fractured instrument is bypassing the segment. Often small manual instruments cannot bypass large fragments especially when these instruments fractured due to tight contact to the root canal wall. The instrumentation of root canals of smaller diameter generates more torsional stress during the cleaning and shaping procedure than when dealing with root canals of larger diameter.20 Attempts to remove these large fragments of fractured instruments with ultrasonics can cause excessive removal of tooth structure and weakening of the root.13,21 In the presented case, a small 0.6 C+ file was used for scouting between the flutes and finding a pathway for small K-files to follow. This instrument was chosen for its unique properties and increased resistance to buckling. Buckling resistance can be defined as elastic lateral deformation when an endodontic instrument is subjected to forces along its axis.22 In a study conducted

by Lopes et al.23 pathfinding endodontic instruments were compared for buckling resistance. In this particular study it was found that C+ plus files showed increased buckling resistance compared to other instruments investigated. In case report 1, the 0.6 C+ instrument managed to bypass the fractured instrument and allowed subsequent instruments for successful removal. It must be emphasized that the C+ file is used for scouting and engagement, but matching size K-files must replace the C+ files once progress is made.

According to the literature, there is no standardized method of instrument removal from root canal systems and often require some initiative from the treating clinician.9,10 However, various techniques and equipment have been suggested including the Masserann Kit manufactured by Micromega, but even the availability of specialized equipment does not guarantee success. Minimally invasive endodontic access must also be considered when using the Masserann kit. This system must be used with great care in

teeth with small diameter roots, curved roots or where instruments fractured in the apical region. A great deal of root dentin is removed with increased risk of perforation and root fracture.24 The creation of a staging platform25 with an altered Gates Glidden bur size 3 should be considered as a maximum diameter for the platform. This technique should only be considered in cases where the fractured instrument can be visualized. Removal of fractured instruments beyond curvatures where no direct vision is possible can be very challenging. There is a high risk of procedural errors and complications and the creation of a staging platform should be carefully considered. In the present case, an effective approach was followed for removal. It must be emphasized that successful removal of fractured instruments requires an adequate skill set, experience and thorough understanding of the use of specialized equipment.

Conclusion The case reports illustrate successful effective approaches to remove 2 different instruments from root canals whilst limiting the loss of tooth structure during removal.

References 1. Iqbal A. The factors responsible for endodontic treatment failure in the permanent dentitions of the patients reported to the college of dentistry, the university of aljouf, kingdom of Saudi Arabia. J Clin Diagn Res 2016; 10(5): 146-148.

2. Sjögren U, Hägglund B, Sundqvist G, Wing K. Factors affecting the long-term results of endodontic treatment. J Endod 1990; 16(10): 498–504.

3. Siqueira JF. Aetiology of root canal treatment failure: why welltreated teeth can fail. Int Endod J 2001; 34(1): 1–10.

4. Grossman LI. Guidelines for the prevention of fracture of root canal instruments,” Oral Surg Oral Med Oral Pathol 1969; 28(5): 746–752.

5. Parashos P, Gordon I, Messer HH. Factors influencing defects of rotary nickel-titanium endodontic instruments after clinical use. J Endod 2004; 30(10): 722–725.

6. Suter B, Lussi A, Sequeira P. Probability of removing fractured instruments from root canals. Int Endod J 2005; 38(2): 112–123.

7. Saunders JL, Eleazer PD, Zhang P, Michalek S. Effect of a separated instrument on bacterial penetration of obturated root canals.

J Endod 2004; 30(3): 177–179.

8. Frota LMA, Aguiar BA, Aragão MGB, de Vasconcelos BC. Removal of Separated Endodontic K-File with the Aid of Hypodermic Needle and Cyanoacrylate. Case Rep Dent 2016; volume 2016: 1-5.

9. Hülsmann M. Removal of fractured instruments using a combined automated/ultrasonic technique. J Endod 1994; 20(3): 144–146.

10. Gencoglua N, Helvacioglub D. Comparison of the different techniques to remove fractured endodontic instruments from root canal systems. Eur J Dent 2009; 3: 90-95.

11. Shiyakov KK, Vasileva RI. Success for removing or bypassing instruments fractured beyond the rootcanal curve – 45 clinical cases.

J of IMAB 2014; 20(3): 567-571.

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12. Madarati AA, Watts DC, Qualtrough AJ. Opinions and attitudes of endodontists and general dental practitioners in the UK towards the intra-canal fracture of endodontic instruments. Part 1. Int Endod J 2008; 41: 693-701.

13. Parashos P, Messer HH. Rotary NiTi instrument fracture and its consequences. J Endod 2006: 32: 1031-1043.

14. Nevares G, Cunha RS, Zuolo ML, Bueno CE. Success rates for removing or bypassing fractured instruments: a prospective clinical study. J Endod 2012; 38: 442-444.

15. Varela-PatiĂąo P, Martin-Biedma B, Rodriguez LC, Cantatore G, Bahillo JG. The influence of a manual glide path on the separation rate of Ni-Ti rotary instruments. J Endod 2005; 31, 114-116.

16. Yum J, Cheung GS, Park J, Hur B, Kim H. Torsional strength and toughness of nickel-titanium rotary files. J Endod 2011; 37: 382386.

17. Castellucci A. Mag-nification in endodontics: the use of the operating microscope. Pract Proced Aesthet Dent 2003; 15(5): 377384.

18. Carr GB, Murgel, CAF. The use of the operating microscope in endodontics. Dent Clin N Am 2010; 54: 191-214.

19. Monea M, Hantoiu T, Stoica A, Sita D, Sitaru A. The impact of operating microscope on the outcome of endodontic treatment performed by postgraduate students. Eur Sci J 2015; 11(27): 305311.

20. Sattapan B, Palamara JEA, Messer HH. Torque during canal instrumentation using rotary nickel-titanium files. J Endod 2000; 26, 156-160.

21. Madarati AA, Qualtrough AJ, Watts DC. Vertical fracture resistance of roots after ultrasonic removal of fractured instruments. Int Endod J 2010; 43: 424-429.

22. Beer FP, Johnston ER. Mechanics of Materials, 3rd ed. New York: Mc Graw-Hill; 1992.

23. Lopes HP, Elias CN, Mangelli M, Lopes WSP, Amaral G, Souza LC, Siqueira JF. Buckling resistance of pathfinding endodontic instruments. J Endod 2012; 38: 402–404.

24. Pai AR, Kamath MP, Basnet P. Retrieval of a separated file using Masserann technique: A case report. Kathmandu Univ Med J 2006; 4: 238-242.

25. Ruddle CJ. Micro-endodontic nonsurgical retreatment. Dent Clin North Am 1997; 41: 429-454.

CLINICAL

Adhesive dentistry meets restorative dentistry and endodontics – part two Osvaldo Zmener1 and Cornelis H Pameijer2

Abstract While there are many similarities with restorative dentistry, endodontics has its own particular problems and limitations with the use of adhesives. Access to the root canal affects acid treatment, rinsing and depth of cure of light curing materials. Light curing resin materials are preferred in restorative dentistry, while dual-curing resins are recommended in endodontics. As to hydrolysis, the effect of MMPs and bacterial leakage, endodontics is equally affected with the use of resins. It is important that practitioners understand the differences between the two specialties when handling these materials.

Key words: Dentine, dentine bonding, endodontics, hybrid layer, resin/dentine interface.

Adhesive dentistry meets the root canal

1

Osvaldo Zmener DDS, Dr Odont, is Head Professor, Postgraduate Program for Specialized Endodontics, School of Dentistry, University of El Salvador/AOA, Buenos Aires, Argentina.

Private Practice limited to endodontics, Buenos Aires, Argentina.

2

Cornelis H Pameijer DMD, MScD, DSc, PhD, Professor Emeritus, University of Connecticut School of Dental Medicine, USA.

Much of what has been presented in ‘Adhesive dentistry meets restorative dentistry and endodontics – part one’ applies to endodontics.

During the last four decades, new materials have been introduced as alternatives to the most widely and traditionally used root canal filling materials (Taintor and Ross, 1978). Gutta Percha does not bond to root dentine and endodontic sealers do not bond to Gutta Percha or to root canal walls, thus allowing for fluid and bacterial leakage. Coronal and apical leakage are both contributing factors to a unfavourable prognosis of endodontic therapy. Recently, the application of adhesive dentistry in endodontics has been improved by the introduction of a new generation of hydrophilic methacrylate-based endodontic sealers and dentine adhesives with the intent to promote the formation of a hybrid layer and enabling the penetration of resin tags into smear layer-free dentinal tubules. Mounce (2007) suggested that adhesive techniques, which are currently being used in restorative dentistry, have now definitively reached the root canal system giving favourable opportunities to improve the resistance to bacterial penetration and to reinforce the root structure. However, clinicians should realise that bonding to root dentine is very different from bonding to coronal dentine. Bonding to root dentine is seriously compromised by polymerisation shrinkage stresses that occur during polymerisation (Condon and Ferracane 2000; Feilzer and Dauviller 2003). The severity of polymerisation stresses is dependent on cavity design (the so called C-factor) and the resin-based sealer thickness (Feilzer et al, 1987; Alster et al, 1997). The Cfactor is the ratio of the bonded to unbonded surface area. Furthermore, as the thickness of the sealer is reduced the shrinkage stresses are also reduced (Tay et al, 2005). The use of indirect bonding methods to compensate for polymerisation stresses may be another method for optimising bond strength to the root canal dentine (Bouillaguet et al, 2007).

Effective smear layer removal and root dentine conditioning before obturation are important steps to improve the penetration of hydrophilic methacrylate-based sealers into the dentinal tubules, thus adhering to the etched and chelating with intertubular

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dentine. In contrast to the coronal areas, the apical third frequently shows irregular dentine structure and fewer dentinal tubules. Some studies have demonstrated that the hybrid layer is thinner in the apical area than the coronal third (Yoshiyama et al, 1996; Ferrari et al, 2000). However, according to Bitter et al (2004) these differences are of minor importance since bonding is determined by the inherent properties of the materials used.

Moreover, although dentine of the apical and middle thirds is frequently sclerotic (Paque et al, 2006) it has also been reported that adhesion to root canal dentine is comparable to that of coronal dentine (Yoshiyama et al, 1996). However, effective bonding of adhesives in the middle and apical thirds of the root canal system is not so easy to obtain. Since effectiveness of a curing light is limited to the coronal third, dual or self-curing adhesives or adhesive sealers must be used. Self-curing resin-based sealers provide some additional advantages. They have less monomer conversion of free radicals compared to light-curing materials. This property is similar to bonding materials in restorative dentistry (Braga et al, 2002) and is responsible for the reduction of contraction stresses. However, the presence of more unreacted monomer is a disadvantage.

Endodontic irrigation solutions have a different effect on bond strength to dentine (Santos et al, 2006). Sodium hypochlorite (NaOCI) is widely used at different concentrations and is successful in dissolving soft tissues (Naenni et al, 2004; Clarkson et al, 2006), as well as having antibacterial properties (Byström and Sundqvist 1983). NaOCl is problematic when resin adhesive materials or resin-based sealers are used. NaOCl is a potent oxidising agent and the oxygen remains on the root canal walls after rinsing, causing polymerisation inhibition of resin-based materials (Ari et al, 2003). NaOCl must be totally removed before filling the root canal space with resin-based materials or resin-based sealers.

The use of 17% or 19% ethylendiaminotetracetic acid solutions (EDTA) for one minute followed by a final copious rinsing with sterile saline has been shown to be effective for this purpose (Baumgartner and Mader, 1987). Since NaOCl only removes the organic component of the smear layer, the chelating action of EDTA helps eliminating the inorganic portion of the smear layer, which can also be contaminated with bacteria. Unfortunately, it has also been demonstrated that the action of EDTA may produce degradation of dentine (Eldeniz et al, 2005), which in turn can be a problem for effective bonding. The remaining oxygen after NaOCl treatment can also be reduced by the

action of ascorbic acid (Perdigao et al, 2000), however, more research on this subject is necessary. Finally, the use of chloroform for retreatment of Gutta Percha filled canals also constitutes an impediment for proper polymerisation of resinbased materials and subsequent bonding to dentine (Erdemir et al, 2004).

Summary and conclusions The use of adhesives in endodontics is essentially confronted with the same advantages and disadvantages and the same problems as in restorative dentistry. One notable exception in restorative dentistry is the advantage of bonding to enamel, which presents fewer problems. Location in the root canal, apical, mid or coronal, determine the effectiveness of the bond, while age, sclerotic dentine, the role of MMPs, use of irrigation solutions and previous root canal treatment are some of the additional factors to be considered.

References Alster D, Verhoven BA, Feilzer AJ, Davidson CL (1997).

Influence of compliance of the substrate materials on polymerization contraction stress in thin resin composite layers. Biomat 18: 337 – 341 Ari H, Yaser E, Belli S (2003). Effects of NaOCl on bond strengths of resin cements for root canal dentine. J Endod 29: 248 – 251 Baumgartner JC, Mader CL (1987). A scanning electron microscopic evaluation of four root canal irrigation regimens.

J Endod 13: 147 – 157 Bitter K, Paris S, Martus P, Schartner R, Kielbassa AM (2004). A Confocal Laser Scanning Microscope investigation of different dental adhesives bonded to root canal dentine. Int Endod J 37: 840 – 848 Bouilleguet S, Bertossa B, Krejci I, Wataha JC, Tay FR, Pashley DH (2007). Alternative adhesive strategies to optimize bonding to radicular dentine. J Endod 33: 1227 – 1230 Braga RR, Ferracane JL, Condon JR (2002). Polymerization contraction stress in dual-cure cements and its effect on interfacial integrity of bonded inlays. J Dent 30: 333 – 340 Byström A, Sundqvist G (1983). Bacteriologic evaluation of the effect of 0.5 sodium hypochlorite in endodontic therapy. Oral Surg Oral Med and Oral Pathol 55: 307– 312 Clarkson RM, Moule AJ, Podlich H, Kellaway R, McFarlane R, Lewis D, Rowell J (2006). Dissolution of porcine incisor pulps in sodium hypochlorite solutions of varying compositions and concentrations. Austr Dent J 51:

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245 – 251 Condon JR, Ferracane JL (2000). Assessing the effect of composite formulation on polymerization stress. J Am Dent Assoc 131: 497 – 503 Eldeniz AU, Erdemir A, Belli S (2005). Effect of EDTA and citric acid solutions on the microhardness and the roughness of human root canal dentine. J Endod 31: 107 – 110 Erdemir A, Eldeniz AU, Belli S, Pashley DH (2004). Effect of solvents on bonding to root canal dentine. JEndod 30: 589 – 592 Feilzer AJ, De Gee AJ, Davidson CL (1987). Setting stress in composite resin in relation to configuration of the restoration. J Dent Res 66: 1636 – 1639 Feilzer AJ, Dauviller BS (2003). Effect of TEGDMA/BisGMA ratio on stress development and vicoelastic properties of experimental two-paste composites.

J Dent Res 82: 824 – 828 Ferrari M, Mannocci F, Vichi A, Cagidiaco MC, Mjör IA (2000). Bonding to root canal: structural characteristics of the substrate. Am J Dent 13: 255 – 260 Mounce R (2007) .Say what you will: the future of endodontic obturation is bonded. Endod Pract 10: 672 Naenni N, Thoma K Zehnder M (2004). Soft tissue

dissolution capacity of currently used and potential endodontic irrigants. J Endod 30: 785 – 787 Paque F, Luder HU, Sener B, Zehnder M (2006). Tubular sclerosis rather than the smear layer impedes dye penetration into the dentine of endodontically instrumented root canals.

Int Endod J 39: 18 – 25 Perdigão J, Lopes M, Geraldeli S, Lopes GC, GarciaGodoy F (2000). Effect of a sodium hypochlorite gel on dentine bonding. Dent Mat 16: 311 – 323 Santos JN, Carrilho MRO, De Goes MF, Zaia AA, Gomes BPF, Souza-Filho FJ, Ferraz CCR (2006). Effect of chemical irrigants on the bond strength of a self-etching adhesive to pulp chamber dentine. J Endod 32: 1088 – 1090 Taintor JF, Ross PN (1978). Opinions and practices of American Endodontic Diplomates. Dent J 44: 321 – 325 Tay FR, Loushine RJ, Monticelli F, Weller RN, Breschi L, Ferrari M, Pashley DH (2005). Effectiveness of resin – coated gutta-percha cones and a dual – cured, hydrophilic methacrylate resin – based sealer in obturating root canals.

J Endod 31: 659 – 664 Yoshiyama M, Carvalho RM, Sano H, Horner JA, Brewer PD, Pashley DH (1996). Regional bond strengths of resins to human root dentine. J Dent 24: 435 – 442 Reprinted with permission from ENDODONTIC PRACTICE May 2018

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Essential guidelines for using cone beam computed tomography (CBCT) in implant dentistry. Part 2: Clinical considerations Johan Hartshorne1 Summary The purpose of Part 2 of this series is to provide dentists with clinical guidelines and recommendations pertaining to: (i) radiographic selection criteria; (ii) indications for CBCT; (iii) how to read a data volume; (iv) application and use; and (v) the advantages and limitations of CBCT in implant dentistry. The knowledge gained and guidelines provided will enhance dentists understanding on when to use a CBCT, how to systematically analyse and read the data volume in order to maximize diagnostic and treatment planning benefits of this technology, whilst optimizing patient safety and minimizing radiation-related patient risk. The potential benefits for accurate assessment, diagnosis of pathologies, identification of anatomical landmarks and neurovascular structures, as well as topographical and morphological deviations in alveolar bone, in pre-surgical treatment planning are undisputed and has resulted in CBCT becoming the new professional standard of care as imaging modality for diagnosis and pre-surgical treatment planning in implant dentistry. A protocol is proposed on how to do a structured review and read a CBCT data volume to ensure that pathosis or critical anatomical structures are not missed that may impact on, and to enhance diagnosis, treatment planning and treatment outcomes. Additionally, CBCT imaging and 3D computer software has significantly increased the accuracy and efficiency of diagnostic and treatment capabilities, thereby contributing towards more predictable treatment outcomes and improved patient care in implant dentistry. With this technology, adequately trained dentists can enhance their practice and best serve the interests of their patients.

Introduction

1

Johan Hartshorne B.Sc., B.Ch.D., M.Ch.D., M.P.A., Ph.D., (Stell), FFPH.RCP (UK) General Dental Practitioner, Intercare Medical and Dental Centre, Tyger Valley, Bellville, 7530 South Africa jhartshorne@kanonberg.co.za

The role of 3D CBCT imaging as a new diagnostic tool in modern day dentistry cannot be overemphasized and has increasingly been referred to as the ‘standard of care’ for diagnostic maxillofacial imaging.1,2,3 It serves as an essential diagnostic tool for clinical assessment and treatment planning and has revolutionized every aspect of how dental implant practices are performed.4,5,6 Traditionally pre-operative information for dental implant diagnostics and treatment planning have been obtained from clinical examination, dental study model analysis, and two-dimensional (2D) imaging such as intra-oral peri-apical, lateral cephalometric, and panoramic radiography. These radiographic procedures, used individually or in combination, suffer from the same inherent limitations common to all planar twodimensional (2D) projections namely, magnification, distortion and angulation discrepancies, superimposition, and misrepresentation of structures.7 When an implant is to be placed in proximity to a vital structure, such as a nerve, artery, or sinus cavity; or where there are bone morphology discrepancies; radiographic information from traditional 2D radiographic imaging is limited due to its inadequacy to properly assess the distance in proximity to vital neuro-vascular or anatomical structures, or when implant placement is potentially violating critical cortical bone margins. The resulting errors from

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the reliance on the traditional imaging leads to potential complications, soft-tissue insufficiency, implant failure, and paresthesia.8,9 Complications may lead to an unsatisfactory patient outcome, referral to other specialists, and subsequent medico-legal claims.2,10 The introduction and widespread use of CBCT imaging over the last decade has enabled clinicians to diagnose and evaluate the jaws in three dimensions, thus replacing computed tomography (CT) as the standard of care in implant dentistry.11 Furthermore, CBCT imaging has revolutionized dento-maxillofacial radiology by overcoming the major limitations of conventional 2-D intraoral, cephalometric and panoramic radiograph12, thereby facilitating accurate pre-surgical treatment planning that is key to successful dental implant rehabilitation. Published studies have reported improved clinical efficacy and diagnostic accuracy of CBCT13,14, compared with standard radiographic techniques for the evaluation of implant sites with challenging unknown anatomical boundaries and/or pathological entities, and for ideal positioning of dental implants.15,16 The value of CBCT imaging as a diagnostic tool has also been reported for various other fields of dentistry such as oralmaxillofacial surgery, dental traumatology, endodontics, temporo-mandibular joint, periodontology, orthodontics, airway analysis and fabrication of implant surgical guides.7,17 As in any new technology introduced to a profession, the education lags far behind the technological advance. This is especially true of cone beam imaging. Dentists are quick to grasp the advantages and applications of using cone beam technology but, once adopted, often make the following statements: “These images are great, but what am I looking at, and where can I get more information on interpreting the scan?�18 An important basic requirement of using CBCT imaging as a diagnostic tool is that practitioners should have appropriate training to develop critical skills for operating CBCT equipment, managing imaging software and acquiring a high level of competence and confidence in using and interpreting CBCT images. Such training should include a thorough review of normal maxillofacial anatomy, common anatomic variants, and imaging signs of diseases and abnormalities. This is particularly important for CT and CBCT imaging because of the complexity of structures within the expanded FOVs.19

of the scientific literature and provide clinical guidelines pertaining to: (i) selecting the appropriate radiographic imaging modality; (ii) indications for using CBCT; (iii) how to read and analyze a CBCT data volume; (iv) clinical application and use; and (v) the advantages and limitations of CBCT in implant dentistry. The knowledge gained and guidelines provided will enhance clinicians understanding when to use a CBCT, how to systematically analyse and read the data volume in order to maximize diagnostic and treatment planning benefits of this technology whilst optimizing patient safety and minimizing radiation-related patient risk. Radiographic images used were obtained from a Kodak Carestream CS9300 CBCT unit.

Guidelines for selecting appropriate radiographic imaging modalities and indications for using CBCT The goal of radiographic selection criteria is to identify appropriate imaging modalities that complement diagnostic and treatment goals prior to and at each stage of dental implant therapy. The following consensus-derived clinical guidelines and recommendations allow practitioners to select the appropriate imaging modality (with particular relevance to CBCT) at each phase of dental-implant therapy.20 The American Association of Endodontists (AEE) and the American Association of Oral and Maxillofacial Radiology (AAOMR) have also jointly developed a position statement to guide clinicians on the use of CBCT in endodontics and to support decision-making when to treat or to extract.21 Additional guidelines have also been published by the European Society of Endodontology.22

Initial examination The purpose of the initial radiographic examination is to assess the overall status of the remaining dentition, to identify and characterize the location and nature of the edentulous regions, and to detect regional and site-specific anatomic structures and pathologies. The initial diagnostic imaging examination is best achieved with panoramic radiography and may be supplemented with periapical radiography.20 The use of CBCT is not recommended as an initial diagnostic imaging examination. However, CBCT may be an appropriate primary imaging modality in specific circumstances, for example when multiple treatment needs are anticipated or when jawbone or sinus pathology is suspected.11

Endodontic assessment decision to treat or to extract Purpose The purpose of Part 2 of this series is to provide an overview

Radiographic imaging is an indispensable component of endodontic diagnosis and treatment planning, i.e. decision

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to do endodontic treatment or to extract, partial extraction therapies, and consideration of dental implant therapy. The AAE and AAOMR21 recommend that intraoral and panoramic radiography be used for the initial evaluation of the endodontic and dental implant patient. Both of these position statements emphasize that CBCT imaging should be used only when the diagnostic information is inadequate by conventional intraoral (periapical X-rays) or extraoral (panoramic) radiography, and when the additional information from CBCT is likely to aid diagnosis and decision making for endodontic treatment or extractions, and planning for immediate or future dental implants therapy. A CBCT with limited FOV is the preferred imaging protocol for most endodontic applications.23 Thus, CBCT imaging should be prescribed for patients who present with nonspecific or poorly localized clinical signs and symptoms of periapical pathology, but in whom conventional radiography fails to identify such pathology.

CBCT is particularly useful in investigating the potential cause for endodontic treatment failures. However, the clinician must recognize that the diagnostic accuracy is influenced by the presence of beam hardening artifacts from metal posts or gutta percha.

Pre-surgical site-specific imaging Pre-surgical site-specific imaging must provide information supportive of dental implant diagnostics and treatment planning goals. Such information includes: (i) quantitative bone volume availability (height and width); (ii) edentulous saddle length; (iii) orientation of the residual alveolar ridge; (iv) anatomical and pathological conditions that can restrict implant placement; and (v) to facilitate prosthetic treatment planning. CBCT is recommended as the imaging modality of choice for pre-surgical diagnostics and treatment planning of potential dental implant sites.20 CBCT imaging is also indicated if bone reconstruction and augmentation procedures (e.g., ridge preservation or bone grafting) are required to treat bone volume deficiencies before or with implant placement. The use of CBCT before bone grafting helps define both the donor and recipient sites, allows for improved planning for surgical procedures, and reduces patient morbidities.

Panoramic views of the posterior maxilla will underestimate the amount of bone available for implant placement and, if relied on, will therefore overestimate the number of clinical situations requiring a sinus augmentation. CBCT can overcome this problem as it provides more accurate measurements of the available bone volume and, in a

proportion of borderline cases, will show that implants can be placed without recourse to sinus surgery.24, 25 Because cross-sectional imaging offers improved diagnostic efficacy, it is the preferred method for preoperative assessment for sinus augmentation surgery.

Postoperative imaging The purpose of postoperative imaging after dental implant placement is to confirm the location of the fixture and crestal bone levels at implant insertion.

Intraoral periapical radiography is recommended for this purpose and is commonly referred to as the baseline image.

Intraoral periapical radiography is also recommended for periodic postoperative assessment of the bone-implant interface and marginal peri-implant bone height implants.20 Panoramic radiographs may be indicated for screening of more extensive implant therapy cases. Titanium implant fixtures inherently produce artifacts such as beam-hardening and streak artifacts with CBCT, obscuring subtle changes in marginal and peri-implant bone. In addition, the resolution of CBCT images for the detection of these findings is inferior to intraoral radiography.

CBCT imaging however, is indicated if the patient presents with implant mobility or altered sensation, especially if the fixture is in the posterior mandible.20,23 to facilitate assessment, characterizing the existing defect, and planning for surgical removal and corrective procedures.

Indications for CBCT in implant dentistry Harris and co-workers26 provide the following guidelines for clinical situations where patients might potentially benefit from CBCT imaging for diagnosis and treatment planning. (i) When the clinical examination and conventional radiography have failed to adequately demonstrate relevant anatomical boundaries and the absence of pathology. (ii) When reference to such images can provide additional information that can help to minimize the risk of damage to important anatomical structures and which is not obtainable when using conventional radiographic techniques. (iii) In clinical borderline situations where there appears to be limited bone height and/or bone width available for successful implant treatment. (iv) Where implant positioning can be improved so that biomechanical, functional, and esthetic treatment results are optimized.

The diagnostic information can be enhanced by use of radiographic templates, computer-assisted planning, and surgical guides.26

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Figure 1: Orthogonal planes (10 x 10 FOV): Axial or horizontal plane (top to bottom cross sections)(upper left), 3D Rendering (upper right), Coronal or frontal plane (front to back cross sections) (lower left), and Saggital plane (right to left or buccal to lingual cross sections) (lower right)

The CBCT scan (data volume) provides cross sections through various planes allowing 3-dimensional evaluation of hard and soft tissues. There are three orthogonal planes (Fig.1): (i) axial or horizontal plane that provides cross sections of the data volume from top to bottom of the FOV; (ii) coronal or frontal or side view, that provides cross sectional views from front to back of the FOV; (iii) sagittal view provides cross sections from buccal to lingual, or left to right of the FOV. Besides the three planes there is also a 3D rendering (Fig.1 – Upper right) A structured or systematic approach for reading a CBCT scan is recommended because there is a huge amount of anatomy contained within the scanned volume and unless a structured approach is used, it is likely that you will miss some information that could impact on your diagnosis and treatment planning.

How to do a structured review of a CBCT data volume All CBCT volumes, regardless of clinical application, should be evaluated in a structured fashion for signs of abnormalities and to ensure that no available diagnostic and treatment planning information is missed. Dental practitioners must not be caught in the trap of only looking at the data they are interested in, such as an impacted tooth or implant site evaluation, or characterization of some pathologic entity that they found in another radiograph. They must examine all the data in the scan and must do so in a systematic and somewhat structured fashion.18 Reviewing CBCT scans can be performed by an adequately trained dentist or specialist treating the patient, or alternatively, a specialist maxillofacial radiologist.20 Critical skills that dentists need for reviewing CBCT scans are: (i) know what they are looking at; (ii) mastering the CBCT imaging software and speaking the CBCT language; (iii) how to manipulate and work through the data volume; (iv) reading the CBCT; (v) analyzing and interpreting the data; (vi) understanding the different anatomical structures that can cause problems in implant placement surgery; and (vii) applying the imaging software to do virtual implant treatment planning. A wide range of video tutorials are available on You Tube and the Internet on how to use CBCT 3D Imaging Software.

To meet these CBCT reviewing objectives, clinicians need to acquire the necessary skills and images should have appropriate diagnostic quality and not contain artifacts that could compromise anatomic-structure assessments. Images should also extend beyond the immediate area of interest to include areas that could be affected by implant placement or vice versa.

Protocol for structured reviewing of a CBCT data volume Each section of the data volume (FOV) must be reviewed and analyzed for possible clinically significant findings. This requires discipline, and it may take some time and practice to establish a pattern so as to make it almost “second nature” to follow this process. In reviewing each of the anatomical structures in the FOV, special attention is paid to the “main complaint” or the reason for the scan acquisition. The purpose of a structured reviewing process is to prevent overlooking significant diagnostic findings that may have an impact on the success or predictability of outcome of implant treatment and any other abnormalities that may lead to medico-legal actions. The following reviewing protocol is based on the Kodak Carestream CS9300-3D unit. (i) Clinical history: Start by reviewing the clinical history, what is the purpose of the data acquisition, which teeth have been removed when, to explain areas of bone loss with healing and/or residual alveolar bone defects. Know if previous bone grafts or socket augmentations were done previously. (ii) Orientation: Open the patient’s data volume. The default scan is usually on ‘Orthogonal Slicing” (Fig.2). Select ‘Curved Slicing’ on the upper menu bar (Fig.3). Identify the three cross-sectional planes: axial is upper left, sagittal is upper right, 3D rendering is lower left, and coronal is lower right (Fig.3). Identify where is left and right and buccal a lingual, and the horizontal (yellow) and vertical (blue and red) lines and cursor buttons used for scouting and orientation vertically and horizontally along the planes.

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Figure 2: Opening the patients data volume defaults on orthogonal slicing. (5x5 FOV) Figure 3: Orientation of patient’s data volume on ‘Curved Slicing’ (5 x 5 FOV) - axial plane (upper left), sagittal plane (upper right), 3D rendering (lower left) and coronal plane (lower right) Figure 4: Activate “Manually Create Arch” on the tools (5 x 5 FOV)

Scout the axial (Top to bottom) (yellow cursor line), coronal (front to back) (red cursor line) and sagittal (right to left) (blue cursor line) planes by moving the horizontal and vertical lines to orient yourself where you are and what you are looking at. (iii) Set arch on the axial plane: Select the ‘Manually Create Arch’ icon on the tool menu on the left side of the image.

(Fig.4) A text box will pop up with prompt: ‘Delete Previous Arch’ Select OK. Move the blue cursor button on the horizontal bar below the axial cross section to get a good cross sectional view of the roots on the arch (Fig.4). Click and draw an arch through the center of the root from left to right side (Fig.5). (iv) Scouting the coronal cross section: Go to the sagittal plane (upper right cross section) (Fig.6). Move the vertical cursor (Blue) from left to right on the FOV to review the coronal cross section (lower right) to identify clinically significant pathosis and neurovascular structures (Fig.6).

Return again to the center of the area of interest with the vertical line in the sagittal cross sectional plane. (v) Scouting the sagittal cross section: Go to the coronal cross section (lower light) (Fig.6). Move the red cursor of the vertical line from buccal to lingual (left to right) to review the upper sagittal cross section to identify any clinically significant pathosis and neurovascular structures. Return again to the center of the area of interest with the red vertical line in the coronal cross sectional plane. (Fig.6) At this stage the ’Nerve Canal Tool’ icon can be activated to plot the inferior alveolar nerve. (Fig.7) (vi) Review area of interest (Implant site): Lastly scout and assess the region of interest (implant site) and adjacent teeth.

4

Note any morphological abnormalities, neurovascular structures, anatomical structures (sinus, nasal), and residual alveolar ridge morphology or other clinically significant findings that may have an impact on implant treatment planning. Move the horizontal line of the sagittal cross section (upper right) to 1mm below the crestal level. (Fig.6) (vii) Implant treatment planning: Software tools can now be applied to facilitate implant treatment planning. Activate the ‘Measurement Mode’ icon in the ‘Tools Menu’ (Fig.7). Go to the axial cross section (upper left) and click buccal and then palatal to measure the bucco-palatal width. Go to sagittal cross section (upper right) and click mesial to distal of the implant site to measure the saddle length of the residual alveolar ridge (Fig.7). Go to the coronal cross section (lower right) and measure the width and length of the residual alveolar bone (Fig.7). If the implant site is in the lower posterior mandible then measure from the crestal level to 2 mm above the inferior alveolar nerve. The correct implant diameter and length can now be selected for this implant site. (viii) Virtual implant selection and placement: Position the vertical line in the correct position of the osteotomy site in the coronal cross section (Lower right). Activate the ‘Implant Placement Tool’ icon in the ‘Tool Menu’ (Fig.8). Select the desired implant type, diameter and length according to the abovementioned measurements. Adjust fine tuning of the implant in its correct three dimensional position by checking all three planes (axial, sagittal and coronal (Fig.9). A stent can also be used to position the vertical line in the correct position where the implant must be placed. (Figure 10) Check placement of the implant in all three planes to assess whether the cortical plate, anatomical structures such as the sinus and nasal cavity, neurovascular structures and neighboring teeth are not violated and that the implant is

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Figure 5: Setting the arch on the axial plane by clicking on centre of the roots to draw an arch (red dots and line).

Figure 6: Scouting the data volume & reviewing the area of interest.

Figure 7: Activating ‘Nerve Canal Tool’ icon to plot the inferior alveolar nerve and ‘Measurement mode’ icon for measuring the implant osteotomy site. Typical implant treatment planning measurements –are saddle length (mesio-distal) (upper right), residual alveolar bone width (bucco-lingual) and vertical length (occlusal-apical) (lower right).

placed in the correct 3D position in the residual alveolar bone for optimal implant stability and a successful prosthetic restoration. Go to the menu bar above the sagittal cross section (upper right) and select ‘Set Integration’ and select 15mm on the scroll down menu to activate ray sum for the sagittal cross section to simulate a typical panoramic X-ray.

The magnification tool can be used to better assess the area of interest (Fig.11) The virtual implant planning and placement can now be communicated visually and discussed with the patient.

Application of CBCT imaging in implant dentistry Successful and predictable implant dentistry requires accurate pre-surgical diagnostics and treatment planning information of the amount of bone available, bone density and the proximity to anatomical structures. Health care providers are also obligated to acquire adequate information from patients to provide a basis for informed patient consent.18 Clinical complexity, regional anatomic considerations, potential risk of complications and aesthetic considerations in the location of implants are factors that determine the individual clinicians needs for information supplemental to that already obtained from the clinical and radiographic examinations (peri-apical and panoramic) to

formulate a diagnosis and to assist in implant therapy treatment planning.27 The introduction and widespread use of cone beam computed tomography (CBCT) over the last decade has enabled clinicians to diagnose and evaluate the jaws in three dimensions, thus replacing computed tomography (CT) as the standard of care for implant dentistry.11 Additionally, multiplanar imaging-reformatting (MPR) of CBCT has significantly increased diagnostic accuracy and efficiency13,14 and offers an unparalleled diagnostic approach when dealing with previously challenging unknown anatomical boundaries and/or pathological entities.15 This has prompted several different organizations to develop clinical guidelines and recommendations for the appropriate use of CBCT for assessing potential dental implant sites. These include the American Academy of Oral and Maxillo-Facial Radiology (AAOMR),20 European Academy of Osseointegration (EAO),26 International Congress of Oral Implantologists (ICOI),28 the Academy for Osseointegration (AO)29 and the International Team for Implantology.”(ITI).11 Cone beam computed tomography (CBCT) has applications in several aspects of dentistry. To appropriately use this technology, clinicians should be able to identify those

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Figure 8: Activate the ‘implant placement tool’ icon to select the type of implant, implant diameter and length.

Figure 9: Virtual implant placement in the correct 3D position.

Figure 10: Using a radiographic stent for virtual implant placement.

Figure 11: Using the magnification tool to assess views in close-up to check that the implant is placed in the correct 3D position.

situations where the information from CBCT is likely to provide useful information, and where this additional information translates into enhanced diagnoses, treatment plans and treatment outcomes.23 The application or use of CBCT in implant dentistry includes: (i) pre-surgical diagnostics and treatment planning; (ii) computer-assisted treatment planning; and (iii) postoperative evaluation focusing on implant failures and complications due to damage of neurovascular structures.13,16

the residual alveolar ridge limiting implant placement.16

Pre-surgical diagnostics and treatment planning Radiographic assessment of the 3D implant position, angulation, and restorative space is essential during presurgical diagnostics and treatment planning of implant sites within the residual alveolar bone. Positioning of single implants within the dental arch can be challenging considering the proximity to adjacent tooth roots, vital structures, occlusal plane, and relative position within the arch.30 CBCT imaging therefore must provide information supportive of the following goals, namely (i) to establish the quantitative bone availability (morphologic characteristics) of the residual alveolar ridge; (ii) to determine the orientation of the residual alveolar ridge; and to (iii) identify local anatomic or pathologic boundaries within

Quantitative bone availability of the residual alveolar ridge (amount of bone available at the implant site Effective pre-surgical assessment requires that clinicians interpret implant sites for many factors related to predictable and successful implant restorations, including adequate bone volumes, distance away from teeth/implants, sufficient prosthetic space for restoration, and precise implant placement. Essential pre-surgical assessment should include an evaluation of the saddle length (mesio-distal), vertical bone height (occlusal-apical), and horizontal width (buccolingual) bone availability of the proposed implant recipient site (Fig.7) to facilitate proper planning, correct implant selection, 3D placement of the dental implant (Fig.9) and the necessity for implant site development.20,30 Most CBCT viewing and analyses software packages feature measurement tools that can be used to easily determine the height and width of bone and the proximity of the proposed implant placement site to adjacent vital structures. With this software the clinician can accurately visualize the 3D alveolar ridge bone contour of a patient and make determinations about surgical entry, implant

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diameter and length, and prosthetic requirements before the surgical procedure.30 CBCT also provides a qualitative assessment of the type of bone (bone quality) and local trabecular architecture (Fig.12a-12c and 13a-13d) to assist in selecting the correct implant type to optimize implant stability. The standard practice is to visually analyze trabecular density and sparseness at the edentulous site. Some studies have explored the feasibility of measuring CBCT gray values at the edentulous area to infer bone quality.31,32 However, there is strong evidence that the relationship between gray value and object density is markedly influenced by several factors, including exposure parameters, FOV and anatomic location.33,34,35,36 Thus, current gray value approaches to quantitatively assess bone quality are unreliable.

CBCT is an essential tool to identify the extent and size of bone defects at potential implant sites that may require augmentation or site development to prepare it for simultaneous or later implant placement.26 Examples where augmentation or site development procedures are required are horizontal bone volume deficiencies (Fig.14), fenestration defects (marginal bone intact) (Fig.15), dehiscence bone defects (denuded areas extend through the marginal bone (Fig. 16a & 16b), post extraction site ((fig.17), vertical bone deficiency (Fig.18), and combined horizontal and vertical bone deficiencies of the alveolar ridge (Fig.19), and sinus floor elevations (Fig.20).

The use of CBCT before bone block grafting helps define both the donor and recipient sites, allows for improved planning for surgical procedures, and reduces patient morbidities.

radiographs, but CBCT provides the advantage of showing the type of alveolar ridge pattern present. Cross-sectional images (coronal view) provide the implantologist with the appearance of ridge patterns, such as irregular ridge (Fig.21a, 21b), narrow crestal ridge (Fig. 21c, 21d)), and knife shape ridge (Fig.21e and Fig.22). Also, the loss of cortical plates and undulating concavities (Fig.23) can also be appreciated on cross-sectional images, and they cannot be seen on panoramic images. In the case of a compromised jaw bone (in terms of quality and/or quantity of bone), the panoramic technique is an inefficient imaging tool. In case of potential risks in treatment plan 3D imaging may prove indispensable.

Bone quality is not only a matter of mineral content, but also of structure. It has been shown that the quality and quantity of bone available at the implant site are very important local patient factors in determining potential implant stability and the success of dental implants. Bone quality is categorized into four groups: groups 1–4 or types 1–4 (Bone Quality Index):37 Type 1: homogeneous cortical bone; (Fig.13a ) Type 2: thick cortical bone with marrow cavity; (Fig.13b) Type 3: thin cortical bone with dense trabecular bone of good strength (Fig.12a, 13c); and Type 4: very thin cortical bone with low-density trabecular bone of poor strength. (Fig.12c) In the jaws, an implant placed in poor-quality bone with thin cortex and low-density trabeculae (Type 4 bone) has a higher chance of failure compared with the other types of bones. This low-density bone is often found in the posterior maxilla, and several studies report higher implant failure rates in this region.37

Ridge morphology (Bone shape and quality) Shape and quality of the bone available

Topography and orientation of the residual alveolar bone

The bucco-lingual ridge pattern cannot be viewed on 2D

12a

The orientation and residual topography of the alveolar-basal bone complex must be assessed to determine whether or not

12b

12c

Figure 12: Qualitative pre-surgical assessment of alveolar bone and trabecular architecture in the maxilla Figure 12a: (Type 2 bone). Figure 12b: (Type 3 bone). Figure 12c: (Type 4 bone).

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13b

13c

13d

Figure 13: Qualitative pre-surgical assessment of alveolar bone density and trabecular architecture in the mandible. Figure 13a: (Type 1 bone). Figure 13b: (Type 2 bone). Figure 13c: (Type 3 bone). Figure 13d: (Type 4 bone).

there are variations that could compromise the alignment of the implant fixture with the planned prosthetic restoration. This is particularly important in the mandible (e.g., submandibular gland fossa) (Fig.24) and anterior maxilla (e.g., labial cortical bone concavity).20 (Fig.25) Information on the topography and orientation of the residual alveolar bone is important to optimize implant selection and placement.

Anatomical considerations, boundaries and limitations (important anatomic landmarks Each location in the dental alveolus has unique morphologic and topographical characteristics owing to edentulousness and specific regional anatomic features that need to be identified and assessed in the diagnostic and treatment planning phase of dental-implant therapy.20 The clinician must have full knowledge of oral-bone anatomy, boundaries and limitations so that any osseous-topography, bone-volume excesses/deficiencies can be identified, to facilitate optimal implant placement and to avoid surgical complications.20 A comprehensive overview of the Oral and Maxillofacial

Figure 14: Horizontal bone volume deficiency requiring augmentation.

anatomy is provided in the literature.15, 37,38,39,40,41,42 For the purposes of this article only the critical anatomical elements related dental implantology is presented.

Anterior maxilla The maxillary anterior region (commonly referred to as the esthetic zone) often presents both surgical and prosthetic implant-assessment complexities.43,44 Subsequent to tooth loss, decrease in the height and/or width of the alveolar process and the development of a labial concavity often necessitate bone augmentation to facilitate implant placement.45 (Fig.25) The morphology and dimension of the nasopalatine (incisive canal) (Fig.26a-26d)46,47,48,49 and the location of the floor of the nasal fossae may also compromise bone availability for implant placement.

Posterior maxilla Atrophy of the edentulous posterior alveolar ridge and pneumatization of the maxillary sinus are the most common causes of lack of bone availability for implant placement in the

Figure 15: Fenestration defect (marginal bone intact) requiring buccal bone augmentation.

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Figure 16a: 3D rendering of a dehiscence defect (denuded areas extend through marginal bone) requiring horizontal buccal bone augmentation.

posterior maxilla. Additionally, the maxillary posterior region has the lowest bone density (Fig. 12c) and the highest implant failure rate.50 Sinus floor elevation surgery along with bone grafting is a well-accepted technique before, or simultaneously with implant placement to increase support in an atrophic maxilla.

Knowledge about the sinus anatomy and residual alveolar ridge is critical before the conduction of surgical procedures.

CBCT images provide an accurate 3-dimensional (3D) representation of the anatomy and are suitable for the detection of morphologic variations in the maxillary sinus to assist with presurgical assessment for sinus augmentation surgery, implant planning and placement.40,42 The available residual alveolar ridge in the posterior maxillary premolar and molar regions are limited superiorly by the floor of the maxillary sinus. (Fig.20 ) Anatomical variations of the maxillary sinuses such as the presence of septa (also known as Underwood septa), number, location and shape, particularly in the inferior sinus wall, complicate sinus floor elevation surgical procedures.23 Sinus septa are bony projection commonly found in the inferior or lateral sinus walls separating the maxillary sinus into 2 or more compartments (Fig.27). Studies show that approximately 45 per cent of patients had at least one septum.51 Strong sinus membrane adhesion at the location of septa, particularly of the inferior sinus wall, may cause perioperative complications, therefore the presence, extent and location of septa must be accurately detected in presurgical radiographic imaging to facilitate proper selection of the surgical technique and prevention of unwanted peri-operative complications and thus increase success rate of sinus surgeries.41,51 Medium-sized or long septa may necessitate a modified surgical approach.

Detection of septa may also influence the decision about the

Figure 16b: 3D rendering of a dehiscence defect (denuded areas extend through marginal bone) requiring horizontal buccal bone augmentation.

location of the window in the lateral window approach during sinus floor elevation surgery.

Assessment of the anterior recess of the maxillary sinus is also important if markedly angled implants are considered for implant-supported edentulous prostheses.)

CBCT can also provide information on arterial channels in the lateral wall of the sinus, presence of apical pathosis (Fig.28) as well as on the health of the sinus such as absence of sinus membrane thickening(Fig.29). In some clinical situations, when there is evidence of sinus pathology, or it is the clinicians opinion that sinus drainage is impaired and may jeopardize the outcome of the procedure to be undertaken, there may be a justification to extend the FOV to include the whole of the sinus including the osteo-meatal complex.52,53,54

Anterior mandibula The anterior mandible is a relatively safe location for implant placement. However, proper diagnostics are essential to avoid intraoperative and postoperative hemorrhage, neurosensory loss, and risk of perforating the cortical plate.

The locations of osseous structures (buccal and lingual cortical plates) (Fig.30) and neurovascular structures include the lingual foramen (Fig.30), the terminal branch of the inferior alveolar nerve at the mental foramen and the anterior loop (Fig.31, 32). The mental foramen is a strategically important landmark during osteotomy procedures in the mandible. Its location and the possibility that an anterior loop of the mental nerve may be present mesial to the mental foramen needs to be considered before implant surgery to avoid nerve injury.55

Posterior mandibula In the posterior mandible, there are several anatomic

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Figure 17: Axial view of a post extraction site at 8 weeks (5x5 FOV).

Figure 18: Vertical bone deficiency in the posterior maxilla.

Figure 19: Combined horizontal and vertical alveolar ridge bone discrepancy in the posterior maxilla.

Figure 20: Vertical alveolar bone deficiencies in the posterior maxilla requiring sinus floor elevation (5 x 10 FOV).

structures that can compromise prosthetically driven, dentalimplant placement. The most important landmarks in the posterior mandibular are the inferior alveolar canal and the submandibular gland fossa (Fig.33, 34, 35). Both these structure can present with anatomic variations that may restrict implant placement and result in complications.

Correct identification of the inferior alveolar (mandibular) canal may assist the clinician to avoid damaging the nerve during surgery and thereby preventing the occurrence of complications such as impaired sensory function and paresthesia of the lower lip and the neighbouring soft tissues,56 It is advisable to measure from the crest of the alveolar bone to the coronal aspect of the IAN and subtract 2 mm to provide a safety zone.

The submandibular fossa is denoted by a lingual concavity or undercut in the posterior mandible and contains the submandibular gland. (Fig.33,34,35)

Physiological, biological and pathological considerations Other local anatomic boundaries and limitations or pathologic conditions that could potentially restrict implant

placement and cause complications include: (i) inadequate distance between neighbouring teeth; (ii) angulation of roots; (iii) apical pathology on neighbouring teeth (Fig.28,36); (iv) impacted teeth (Fig. 36, 37) (iv) residual roots; and (v) presence of foreign material (Fig.38).

Computer assisted prosthetic and surgical treatment planning Apart from the diagnostic capabilities, dental CBCT may also offer therapeutic capabilities through computer assisted surgical and prosthetic treatment planning via computer-aided design/computer-aided manufacturing solutions.13,26 CBCT DICOM data is merged with stereolithography (STL) files from an Intra-Oral optical scanner to produce a 3D rendering (3-D Conversion) model of the jaw for virtual planning.30 Virtual planning software is used to construct a virtual wax-up and to place the implant fixture its correct 3Dposition on the virtual 3-D model. Information to be gathered from the combination of high-quality CBCT images and STLfiles should include locations of vital structures, desired implant positions and dimensions, the need for augmentation therapy,

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21a

Figure Figure Figure Figure Figure

21b

21c

21d

21e

21a: Coronal view of an irregular alveolar ridge in the maxilla.

21b: Coronal view of an irregular alveolar ridge in the mandibula.

21c: Coronal view of a narrow crestal alveolar ridge in the mandibula.

21d: Coronal view of a narrow crestal alveolar ridge in the maxilla.

21e: Coronal view of a knife–shape crestal alveolar ridge in the mandibular.

and the planned prostheses.11 Once the design is completed it is submitted to a milling machine or a digital printer for fabrication of a surgical guide. The guide can be bone, tooth or mucosal supported. The actual surgical guide is milled or printed, all with round cylinders, allowing dedicated instrumentation (drill bits) to be precisely guided, creating osteotomies and guiding the implant in its correct or ideal 3Dposition during placement.11 Implants placed utilizing computer-guided surgery with a follow-up period of at least 12 months demonstrate a mean survival rate of 97.3% (n = 1,941), which is comparable to implants placed following conventional procedures.11 To improve image data transfer, clinicians should request radiographic devices and third-party dental implant software applications that offer fully compliant DICOM data export.11 It is important to realize that errors can occur when transferring information from a cross-sectional computer image to the

Figure 22: Knife–shape crestal alveolar ridge in the posterior maxilla.

surgical situation. The surgeon should be aware of these and be careful to allow an adequate “safety margin” in all cases.26 The use of guided surgery for implant placement is increasing because of a number of clinical advantages, including increased practitioner confidence and reduced operating time.

Post-operative radiographic assessment of implant failures and complications (i) Altered sensation and possible damage to neurovascular structures CBCT may offer surgical guidance and therapeutic possibilities and cases of altered sensation and possible damage to neurovascular structures. Current evidence supports the protocol that a CBCT be used following the neurosensory assessment to pinpoint lesion location as well as confirmation of IAN injury.57 Proper pre-surgical planning,

Figure 23: Serial axial images of the maxilla showing undulating buccal bone concavities due to missing anterior teeth (5 x 10 FOV).

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timely diagnosis, and treatment are key factors in avoiding and managing neurovascular complications and damage after implant placement (Fig.38).57

restorations. This prevents misaligned implants, which may be difficult or impossible to restore, and avoids poor aesthetics and function.

(ii) Infection or post-operative integration failure

Prevention of injury to nerves: Using the CBCT, the surgeon maps out the path of the sensory nerves in the jawbone and selects the right implant length. Conventional X-rays are flat and distorted and are poor diagnostic images for predicting the position of the nerves. Nerve damage from dental implant placement results in partial or complete numbness of the lip and chin area, which can be potentially permanent.

CBCT is a mandatory imaging technique to prevent this serious complication.

CBCT is indicated for implant failure cases, infection or postoperative integration failure, owing to either biological or mechanical causes. A CBCT can provide therapeutic assistance with characterizing the existing defect, plan for surgical removal and corrective procedures, such as ridge preservation or bone augmentation, and assess what the implications of surgical intervention is on adjacent structures.

Cross-sectional imaging, optimally CBCT, should also be considered if implant retrieval is anticipated.20

Prevent implant penetration into the sinus: CBCT provides (iii) Implant displacement The use of CBCT scans are helpful in post-operative evaluation of implant displacement into the sinus or nasal cavity (Fig.39).58

(iv) Perforations The major potential risks of encountering a lingual plate perforation (Fig.40) are massive haemorrhage of the submental and sublingual arteries (anterior mandible)59 and airway obstruction60 Perforation of the lingual concavity above the mylohyoid ridge might injure the lingual nerve.61 If the extruded implant is left unattended, the infection might spread to the parapharyngeal and retropharyngeal space, leading to more severe complications, such as mediastinitis, mycotic aneurysm formation with possible subsequent rupture of the internal carotid artery, and internal jugular vein thrombosis with septic pulmonary embolism or upper airway obstruction.62

an accurate picture of the maxillary sinus and its position in relation to the available bone. The surgeon can make an accurate measurement and select the right implant length to avoid puncturing the maxillary sinus. Penetration of the maxillary sinus can lead to sinusitis or other inflammatory conditions. The surgeon can also plan for necessary bone grafting if there is insufficient bone to support the implant.

Conventional X-rays are highly inaccurate for these purposes and do not provide the information necessary for the safe placement of dental implants in the posterior maxilla.

Selection of the right size implant for optimal support: The longevity and success of dental implants require maximal integration and stability in the bone. CBCT allows the surgeon to measure the available bone and select the widest and longest implant appropriate for the site. This, in turn, helps to support the high bite (occlusal) forces and avoid potential failure from overload. Implant size selection should

Advantages and limitations of CBCT in implant dentistry There are six major benefits of cone beam CT scan (CBCT) for dental implant planning and placement:63

Precision placement of implants in the bone: CBCT allows the surgeon to accurately measure and localize the available bone and accurately place the implant in a correct 3D position. This is verified by virtual implant placement.

Proper orientation of the implant with its overlying restoration: A CBCT can be merged with an optical scan of the patient’s teeth (digital impression) to create a complete bone, teeth, and soft tissue digital model. This will facilitate precise postioning of implants to support planned

24

25

Figure 24: Coronal view of the topography and orientation of the residual alveolar bone in the submandibular gland fossa area.

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Figure 26a: Axial view of morphology of the nasopalatine canal (incisive canal) in the anterior maxilla (5 x 10 FOV).

Figure 26b: Coronal view of morphology of the nasopalatine canal (incisive canal) in the anterior maxilla (5 x 10 FOV).

Figure 26c: Serial axial views of the nasopalatine canal.

Figure 26d: Serial coronal views of implant placement planning in relation to the nasopalatine canal in the anterior maxilla.

Figure 27: Sinus septa in the inferior sinus wall.

Figure 27: Apical pathosis in the posterior maxilla.

not be guesswork! Implant selection is made based on precise measurements, biological requirements, bite scheme, and individual patient needs.

a mandatory diagnostic imaging for every implant treatment.

Not using CBCT for planning is unwise for the surgeon and creates unnecessary risk for the patient and clinician.

Improved clinical outcomes and reduced risk of complications

Communitation of data volume

CBCT offer a more accurate, predicatable outcome and safer means to dental implant placement. CBCT should be

CBCT allows the ability to communicate DICOM data imaging information for prosthetic restorative planning, and design and manufacturing of surgical guides.

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Figure 29: Implant planning in the posterior maxilla and sinus membrane thickening.

Figure 30: Buccal and lingual cortical plates in the anterior mandibula and lingual foramen.

Figure 31: Mental foramen and anterior loop and terminal branch of the inferior alveolar nerve.

Figure 32: Serial coronal cross sections of mental foramen in the anterior mandibula.

Limitations of CBCT Requires training and has a learning curve It requires new competencies from the clinician and the value of information obtained is interpretation sensitive. This requires training and new knowledge from the clinician.64

Large FOV may requires expertise and specialized monitoring equipment Referral to an Oral Maxillofacial Radiologist may be indicated for need of expertise and because a proper monitor, ambiente lighting, and equipment settings may be available only in a specialist radiologist environment64, especially where larger FOV are required for advanced and full dental reconstructions.

Poor soft tissue contrast One major disadvantage of CBCT is that it can only demonstrate limited contrast resolution. If the objective of the examination is hard tissue only, then CBCT would not be a problem. However, CBCT is not sufficient for soft tissue evaluation.7,65 It provides limited resolution to deeper (inner) soft tissues and MRI and CT are better for soft tissue imaging.64

Imaging artifacts Streaking and motion artefacts, although limited, cannot be avoided. These artifacts contribute to image quality degradation and can lead to inaccurate or false 64,68 diagnosis.

Bone density and grayscale CBCT is commonly used for the assessment of bone quality primarily for pre-implant treatment planning. Traditionally bone quality has been based on bone density, estimated through the use of Hounsfield units derived from multidetector CT (MDCT) data sets. However, due to crucial differences between MDCT and CBCT, which complicate the use of quantitative gray scale values (GV) for assessment of bone density with CBCT.66 Experimental and clinical research suggest that the qualitative use of GV in CBCT to assess bone density should be avoided at this stage.66 Current scientific literature suggests a paradigm shift of bone quality assessment from a density-based analysis to structural evaluation.66

Radiation dose The radiation dose from CBCT is lower than conventional

58 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 13, NO. 4

HARTSHORNE

Figure 33: Inferior alveolar canal and submandibular gland fossa in the posterior mandibula.

Figure 34: Inferior alveolar canal and mental foramen showing the anterior loop of the mental nerve.

Figure 35: Implant planning in the posterior mandibular showing implants in relation to the inferior alveolar canal and the submandibular glad fossa.

Figure 36: Apical pathosis en impacted premolars.

Figure 37: Axial view of impacted premolars in relation to the osteotomy sites.

Figure 38: Foreign body located in the osteotomy site.

CT, but is significantly higher than traditional radiographic modalities (peri-apical, Panoramic).64

Conclusions CBCT

imaging

technology

computer

software

has

significantly increased the accuracy and efficiency of diagnostic and treatment capabilities, thereby offering an unparalleled diagnostic approach when dealing with previously challenging unknown anatomical and/or pathological entities in implant dentistry. The potential

60 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 13, NO. 4

HARTSHORNE

Figure 38: Using CBCT for neurosensory assessment and confirmation of inferior alveolar nerve injury.

(With permission from Dr Howard Gluckman).

Figure 39: Using CBCT for post-operative assessment of complications such as implant placement into the nasal cavity (With permission from Dr Howard Gluckman).

Figure 40: Implant perforating the lingual cortical plate (With permission from Dr Howard Gluckman).

benefits for accurate assessment, diagnosis of pathologies, identification of anatomical landmarks and neurovascular structures, as well as topographical and morphological deviations in alveolar bone, in pre-surgical treatment planning are undisputed. CBCT has thus become the new professional standard of care as imaging modality for diagnosis and pre-surgical treatment planning in implant dentistry.

The decision to prescribe a CBCT scan must be based on the patient’s history and clinical examination and justified on an individual basis taking due consideration of diagnostic and pre-surgical treatment planning needs and benefits, radiation risk and cost. Effective assessment of proposed implant sites requires that clinicians interpret implant sites for many factors related to successful implant restorations, including adequate bone volumes, distance away from teeth/implants, sufficient prosthetic space for restoration, and precise implant placement. A protocol is proposed on how to do a structured review and read a CBCT data volume to

ensure that pathosis or critical anatomical structures are not missed that may impact on, or enhance diagnosis, treatment planning and treatment outcomes.

CBCT is increasingly being accepted as the new professional standard of care in implant dentistry. With this technology, adequately trained clinicians can enhance their practice and best serve the interests of their patients.

However, with growing technological and software development and increasing utilization of this indispensible technology, it is important that the dental profession develop evidence-based guidelines and Figure 41: Streaking artefact recommendations for its proper from dental implant. and effective use.

VOL. 13, NO. 4 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION 61

PRODUCTS

GKE

RENFERT

ULTRASONIC BATH - CLEANING PROCESS MONITORING INDICATORS

SYMPRO

Denture Cleaning Unit Compact, high-performance cleaning unit especially suitable for dentures, orthodontic appliances and other dental restorations.

Designed to help you monitor your cleaning process Indicators are available in 4 different colours and can be tailored to monitor the cleaning efficacy of your ultrasonic cleaning process.

Recommended for use at least once per day or in every load to ensure no changes in process parameters have occurred. A failed result indicates sub-optimal performance of the process, prompting the end-user to consider all parameters – Does the detergent require changing? Was the correct dose used? Are the transducers performing optimally? Indicators do not replace mandatory daily checks on machine performance, but can enhance how you monitor your process, and identify where the cleaning process may be compromised.

Advantages • Validated, hygienic treatment of bowls (cleaning bowl for 2 dentures, minicup for 4 single crowns or for bridge of 4 elements), needles and tweezers.

• Up to 80% time savings compared to conventional methods thanks to effective and automated cleaning process.

• Increased customer retention with a prophylaxis service for denture wearers.

Details • Cost-effective cleaning of small objects in the optional SYMPRO mini cup.

• Optimal and fast cleaning performance due to an inclined bowl at 35°.

DIRECTA

QUINTESSENCE BOOKS

HYGOVAC® BIO

BOTULINUM TOXIN FOR FACIAL HARMONY Altamiro Flávio

New, fossil free aspirator tubes made from renewable resources Manufacturers of products can make a difference regarding global warming caused by greenhouse gases. By using aspirator tubes made in bio-based polyethylene, we can reduce the level of carbon dioxide in the atmosphere and help save our planet for future generations.

The new Hygovac® BIO uses plastic made with alcohol derived from sugar canes. Hygovac® Bio by Orsing gives the option to choose a length which suits the treatment, now available in two new sizes, 120 mm and 95 mm.

This book outlines the many clinical uses for Botox, with detailed illustrations and case presentations to support each procedure. The first part of the book covers systematic facial analysis, photographic documentation, and how to plan treatment. Special attention is paid to the anatomy and physiology of the face and the identification of injection points. Detailed treatment instructions for dosage, syringe type, and needle size are included for each procedure, as well as guidelines on how to evaluate results anthropometrically to determine whether esthetic treatment goals have been met. This stunning book will change the way you approach facial analysis and widen your esthetic treatment options for patients.

All products available from: HENRY SCHEIN • Tel: 1300 65 88 22 • www.henryschein.com.au

62 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 13, NO. 4

PRODUCTS

BIOHORIZONS

ENDOSEQUENCE

TAPERED 4.2 IMPLANT

BC SEALER

Calcium silicate radiopaque sealer dispensed from single premixed paste syringe

BioHorizons new Tapered 4.2 implants feature aggressive, self-tapping buttress threads that provide progressive insertion torque and compressive loading for primary stability. The platform-switched Laser-Lok collar creates a connective tissue attachment and retains crestal bone. Tapered 4.2 implants use the BioHorizons 3.5mm conical internal hex connection, maintaining compatibility with existing components and can be placed using existing BioHorizons Tapered surgical kits.

Introducing a revolutionary premixed and injectable root canal sealer utilizing new bioceramic nanotechnology! EndoSequence BC Sealer’s nano particle size allows it to flow readily into canal irregularities and even dentinal tubules and unlike traditional sealers; EndoSequence BC Sealer has absolutely no shrinkage! This highly radiopaque and hydrophilic sealer chemically bonds to both dentin and to our bioceramic gutta percha. It uses the moisture naturally present in dentin to initiate and complete its setting reaction and it is anti-bacterial during setting due to its highly alkaline pH. White colour with excellent ease of use.

DIRECTA

QUINTESSENCE BOOKS

CALASEPT SINGLE DOSE

OROFACIAL PAIN: GUIDELINES FOR ASSESSMENT, DIAGNOSIS, AND MANAGEMENT, SIXTH EDITION

Calasept Plus is pure calcium hydroxides, a ready-to-use paste in an air tight syringe for direct application through the Flexi-Tip. With its multi purpose Calasept Plus can be used for temporary root-filling, pulp capping, pulp protection, insulation in deep cavities and for stepwise excavation. The new Calasept Plus single dose packaging will always give a fresh syringe for time saving, precise and safe applications.

• Long-lasting and very effective • Smoother consistency • Precise and deep application with Flexi-Tip • Five indications – only one product *Pack of 3 x 0.4ml Syringe

Reny De Leeuw & Gary Klasser Following in the tradition of the previous editions, this book offers the latest research and most up-to-date information on orofacial pain, including a concise overview of each condition as well as its symptoms, comorbidities, differential diagnosis, and treatment options.

Every chapter has undergone critical updates to reflect the developments in the expanding field of orofacial pain, including the glossary. These updates include the addition of new diseases such as first-bite syndrome, revised information on genetic factors to reflect new insights gleaned from the OPPERA studies, expanded information on management strategies for certain conditions, and revisions to screening tools for biobehavioral factors.

All products available from: HENRY SCHEIN • Tel: 1300 65 88 22 • www.henryschein.com.au

64 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 13, NO. 4