Orthodontics
Ailbhe McMullin David Waring and Ovais Malik
Invisible Orthodontics Part 2: Lingual Appliance Treatment Abstract: The aim of this second article of the three part series is to sum up the current developments in lingual orthodontics. This article attempts to review the development, advantages and disadvantages, bonding techniques, bracket mechanics, patient factors and types of lingual appliance systems available. In addition, the article shows examples of treated cases with lingual appliances. Clinical Relevance: Lingual appliances are a useful addition to the armamentarium of invisible orthodontic appliances, with significant developments over the last few years. Clinicians need to be aware of the advances and predictable results achievable with lingual appliances. Dent Update 2013; 40: 391–402
A review of the literature1 suggests that, as far back as 1726, Fauchard introduced using appliances on the lingual surfaces of teeth. However, it was Fujita2 in the 1970s who is credited with pioneering modern lingual treatment with lingual brackets and ‘mushroom-shaped’ archwires. Interestingly, this came about to address the demands
Ailbhe McMullin, BDentSc(Hons), MFDS RCS(Ire), Specialist Registrar in Orthodontics, University of Manchester Dental Hospital, David T Waring, BChD, MDentSci, MFDS RCS(Eng), MOrth RCS(Ed), FDS(Orth) RCS(Ed), Consultant in Orthodontics, University of Manchester Dental Hospital and Northenden House Orthodontics, Sale Road, Manchester M23 0DF and Ovais H Malik, BDS, MSc(Orth), MFDS RCS(Ed), MOrth RCS(Eng), MOrth RCS(Ed), FDS(Orth) RCS(Eng), Consultant in Orthodontics, University of Manchester Dental Hospital, Salford Royal NHS Foundation Trust, Stott Lane, Manchester M6 8HD and Northenden House Orthodontics, Sale Road, Manchester M23 0DF. June 2013
of martial artists undertaking orthodontic treatment. The poor outcome of completed cases triggered a drop in interest in the 1990s, but with technological advances there has been a recent resurgence in the use of lingual appliances.
Bracket mechanics Since the initial suggestion that brackets could be placed behind the teeth in the 70s, several American orthodontists formed the Lingual Task Force to promote the use of lingual appliances. This has led to the development of numerous lingual appliance systems. Table 1 gives a breakdown of the brackets currently available. Ormco Corporation (Orange, CA, USA) produced one of the first bracket systems following work undertaken by Kurz et al;5 this was placed as an edgewise appliance. As access is difficult and there is a lack of direct visualization of the lingual surfaces, numerous indirect bonding set-up systems have developed as an alternative to direct bonding. Published research has suggested significant improvement in bracket position with reduced torque and rotational errors using an indirect bonding system.6 A high degree of accuracy
can therefore be achieved using these techniques in bracket positioning. The chairside bond-up time is also reduced. Table 2 lists some of the main bracket set-up systems and outlines their main features. Actual bonding protocols have also advanced over the last decade. Previous problems relating to the increased debonding of brackets negatively influenced the lingual technique in the US during the 1980s.9 The standard technique was difficult to employ with bracket positional discrepancies and inaccuracies in finishing. There are both clinical and biomechanical differences between labial and lingual orthodontics. Lingual tooth surfaces have a greater slope than the labial side and a more irregular anatomical form. The built in bracket prescription tends to be expressed later in lingual treatment.10 It is harder to correct rotations due to the small arch perimeter and the decreased interbracket distance. Kurz and Bennett suggest the shorter interbracket distance decreases torque control and leads to a more obtuse interincisal angle and more upright incisors, especially in extraction cases.11 In the horizontal plane, the inter bracket distance is reduced compared to labial orthodontics, which produces less DentalUpdate 391
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Orthodontics
Conventional Brackets1
Ormco 7th Generation Lingual Bracket
Evolved from Kurz lingual bracket design Hooks on bracket help secure the archwire A rhomboid-shaped bite plane helps with overbite reduction, incisor intrusion and aids expansion Optional tube on molar brackets for transpalatal arches
Incognito/iBraces
3D scanning and CAD-CAM technology with prototyping used to generate customized brackets made of a very hard alloy with high gold content Tip and torque prescriptions are individualized Vertical slot with vertical archwire insertion direction A computer-controlled robot bends customized archwires
Self-Ligating Brackets3,4
Forestadent Philippe 2D SL Bracket Forestadent 2D Lingual SL Bracket − 3rd Generation Adenta Evolution LT – 2nd Generation
Wings are closed against the base to hold the archwire Lacks 3D control as there is no slot 4 types − standard, narrow single wing, large twin & three wing
Figure 1. ‘Mushroom-shaped’ archwire.
Options include a T-hook for securing elastic chain, a gingival hook for intermaxillary elastics or a plus bracket to apply individual torque
compounding known difficulties with anterior torque control in lingual appliances. The mushroom archwire formation has an area of weakness between the canines and premolars, which is prone to fracturing. More recently, lingual straightwire techniques have evolved with modifications in the bonding heights and the positioning of canine and premolar attachments to eliminate the use of mushroom loop archwires.8 Brackets are placed as close as possible to the tooth surface, which reduces the slot-tooth distance, improving 3D control of tooth positions. Mechanics are easier with straight archwires and it is suggested that there is improved patient comfort. Table 3 outlines the types of cases which are suitable for lingual therapy, and those that are not. The advantages and disadvantages are listed in Table 4. As with any new technique, there is a learning curve associated with switching from labial to lingual appliance therapy. Access and visualization of the working area are reduced and there is a different range of factors to which to adapt.
One piece bracket with clip opening at the incisal edge Allow archwire insertion from occlusal direction In crowded cases it can be difficult to close all the clips Can accept auxiliary springs for extra torque and tip control Increased maxillary incisor torque, decreased buccolingual thickness and a stronger clip
Ormco Scuzzo/ Passive self-ligating 3D system with interbracket distance maximized Takemoto All brackets feature a hook and a gingivally offset pad for more incisal bracket Bracket (STb) placement STb Light Lingual Full-arch system using very light forces STb Social 6 Used on anterior teeth with minor to moderate crowding or spacing GAC In-Ovation-L Bracket
Twin horizontal slot with interactive clip for ease of opening Minimal buccolingual width and low profile allows for larger archwire perimeter and increased interbracket distance
Gestenco Phantom Bracket
Polyceramic system Rounded margins to improve patient comfort
Table 1. Types of lingual bracket systems.
flexibility in the archwire. Therefore a more flexible wire should be used to compensate for this and allow for physiological tooth movement. A 3D finite element model study12 found identical loads in labial and lingual orthodontics produce very different results − translation and uncontrolled tipping with intrusion, respectively. When retracting incisors it is suggested that one uses mild
392 DentalUpdate
forces and that the root torque is increased. Most bracket systems rely on the use of ‘mushroom-shaped’ archwires with canine, premolar and molar offsets (Figure 1) as their set-up method is based on individualized resin pads to compensate for the differences in tooth thicknesses. This results in particularly the incisor attachments being further from the lingual surfaces,
Patient factors Patients do report problems with lingual appliances, including altered speech, tongue soreness, difficulty maintaining oral hygiene and adherence of food between brackets. Lingual brackets alter the morphology of the lingual surface and the second articulation zone, leading to difficulty with speech performance, in June 2013
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Orthodontics
Lab System Set-Up Model?
Mode of Positioning
Advantages
Disadvantages
CLASS System √ Separate metal plates aid anterior/posterior positioning (Custom Lingual Transfer to original model via acrylic caps Appliance Set-up Service)
1st order bends not needed in labial segment as tooth thickness factored in
Multi-step process Errors in transfers cumulative
TARG System Χ Brackets at same distance from incisal/occlusal plane (Torque Silicone/ thermoplastic transfer tray Angulation Reference Guide)
Possible to prescribe torque & angulation for each tooth individually
Many 1st order bends required as thickness of teeth not factored in
BEST System Χ Caliper to measure tooth thickness No need for bends in (Bonding with Built-in compensation for differences in tooth thickness anterior section of Equal Specific wire Thickness)
Archwire bends between canine and premolar, premolar and molar required
LBJ (Lingual Χ Set of 6 anterior, 1 universal posterior jig plus a special ruler Bracket Jig) Transfers Andrews labial prescription to lingual
Limited number of jigs available
TOP (Transfer Optimized Positioning)
√ Virtual target set-up
Allows indirect and direct bracket positioning
TARG Professional used High levels of Slots aligned in virtual archwire plane with height, precision angulation and torque set 1st order adaptation performed manually
Customized brackets with high gold content expensive
KIS System √ All brackets positioned at once (Korean Indirect Bonding Set-Up)
Simpler and faster Allows for bracket height differences
Special model gauge required for precise set-up model
Hiro System √ Full-sized rigid rectangular wire used to aid bracket positioning Individual bracket transfer trays made
No need for 1st order bends in labial segment (customized resin pads)
Initial bond-up appointment longer Need new tray if debond occurs
Orapix System √ Model scanned to create 3D data file (3Dxer) Virtual 3Txer software creates virtual set-up & transfer trays set-up Manually position brackets in trays
Straightwire principles can be used Compatible with any bracket system
Orapix software required by clinician to finalize the set-up Expensive lab costs
Table 2. Overview of bracket set-up systems for lingual appliances.7,8 Favourable Cases for Lingual13
Unfavourable Cases for Lingual13
Mild incisor crowding and anterior deep bite Long uniform lingual tooth surfaces without fillings, crowns or bridges Good periodontal health Keen, compliant patient Patients can adequately open their mouths and extend their necks
Short abraded and irregular lingual surfaces Heavily filled/restored dentitions Limited ability of patient to open his/her mouth Patients with cervical ankylosis/neck problems Incompletely erupted dentitions
Table 3. Favourable and unfavourable cases for lingual appliance treatment. Advantages of Lingual Therapy
Disadvantages of Lingual Therapy
Aesthetic Bracket design can help with bite opening and intrusion of teeth Accurate bracket positioning systems available Lower incidence of white spot lesions compared to labial therapy14 Adaptable − can combine upper lingual with lower labial appliances
Expensive and require laboratory input Access and direct visualization limited for operator Alters speech15 Patient discomfort especially tongue soreness16 Difficulty maintaining oral hygiene Mechanics differ from labial therapy
Table 4. Advantages and disadvantages of lingual appliance treatment.
June 2013
particular ‘s’ and ‘t’ sounds. Both patients and speech professionals rate speech as poorer with lingual appliances, with most but not all overcoming speech issues by debond.15,16 This contrasts with labial appliance patients who report some speech alteration initially which recovers within a month. The onset of pain has been found to be earlier with lingual compared to labial appliances.17 There does, unsurprisingly, seem to be a difference in the areas of discomfort between lingual and labial fixed appliances, with tongue soreness and speech difficulties greater in lingual appliances and cheek and lip soreness greater in labial appliances.18 Tongue soreness, a particularly uncomfortable feature, is often graded as severe and can persist until lingual appliance removal. A significant negative correlation has been established between SNA and SNB angle and the restriction of tongue space DentalUpdate 393
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Orthodontics
with those with SNB less than one deviation below normal values experiencing more severe restriction of the tongue space.19 The newer lingual appliance systems that are custom made to fit an individual lingual tooth surface tend to be able to incorporate a lower profile of bracket. This has been shown to produce fewer tongue restriction problems, speech disturbances and impairments in chewing and biting.20 While much of the published research in lingual orthodontics has concentrated on the bracket mechanics, there has been little assessment of patient factors, although there appears to be increasing interest in the qualitative aspects of this system. Previously, in a patient-based study,21 it was suggested that the lingual technique appealed to a certain patient type, with females accounting for a higher patient uptake (75%), although this is also a widespread finding in labial fixed appliances. Clearly, the aesthetic aspect was the major factor in undertaking treatment with lingual appliances, as 53% of the patients would have refused orthodontic treatment with conventional/ceramic brackets placed labially. The initial irritations were mainly affecting the tongue (65%), but also speech impairment (24%) induced by the lingual appliance. It is generally accepted that placement of a single arch in separate visits rather than bonding of both arches in a single visit assists in patient comfort.22 The ideal malocclusion for lingual appliance treatment is a low angle deep bite case. In addition, Class I or Class II cases with pre-molar extractions are appropriate simple, predictable cases to begin therapy with lingual orthodontics, whereas full pre-molar extractions, posterior crossbites, anterior open bites and increased mandibular plane angle cases are difficult lingual appliance cases.23
Custom-made appliances New lingual bracket systems are continuously being developed including simpler methods of bonding and ligation methods. Using the latest technology in CAD/CAM processes, Weichmann has produced a system (Incognito) that combines low profile customized brackets with an indirect bonding system.24 This has the advantages of: Lower profile of bracket for patient comfort;
394 DentalUpdate
Accurate re-bonding of brackets with a health was satisfactory, despite less then bracket base to fit exactly the tooth surface; desirable hygiene levels. Improved finishing; The aim of treatment was Precise initial placement using a transfer tray; alignment of upper and lower arches with Increased torque control with customized Class 1 incisors and molar relationship. bracket slot. Owing to the severity of crowding in both Indirect bonding requires upper and lower arches, all first premolars excellent technique with adequate moisture were extracted. The treatment plan involved control and effective teamwork. The tooth an upper lingual appliance (Incognito, surface should be appropriately prepared for the bonding, with use of a sand blaster a followed by the recommended bonding technique. Customized brackets have the advantage of requiring less filler/resin to compensate for the lingual surface and, as a result, have a lower profile bracket. A customized approach also allows straightwire mechanics to be used − especially useful in the buccal segments during space closure. The Incognito system provides a series of archwires, which reduces the need for wire bending, which can be especially difficult in lingual orthodontics.
Non-customized appliances
b Lingual appliance brackets have been popularized recently as direct placement non-customized brackets. These have the advantages of being less expensive and can be used for simple alignment of mild crowding cases. Examples include Forestadent Philippe 2D brackets and the STb (Scuzzo/Takemoto) system (Table 1). They can also be prepared for indirect bonding using a transfer jig. As a result of the bracket base being a standard uniform surface, there will be an increase in filler to compensate for the tooth surface and less predictable bonding. There are also the patient factors as discussed previously. These will continue c to develop and produce improved noncustomized bracket systems and pre-formed archwire sequences.
Case 1 (Figures 2−11) This young adult female was concerned about crowding of her upper and lower teeth. She did not want to wear a conventional upper fixed appliance. Intraorally she presented with a mild Class III incisor relationship with severe crowding of her upper arch and moderate crowding of the lower arch. In the upper arch, both the upper canines were excluded from the line of the arch and displaced labially. Periodontal
Figure 2. (a-c) Pre-treatment extra-oral views of Case 1.
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Orthodontics
a
b Figure 5. Alignment stage in the upper arch with 0.018” NiTi archwire.
c
Figure 7. Mid-treatment extra-oral view showing the invisible nature of the upper lingual appliance.
Figure 6. Complete alignment of upper arch being achieved with rectangular NiTi archwire.
d
a
d
b
e e c
Figure 3. (a-e) Intra-oral views of Case 1 showing severe crowding of the upper arch and moderate crowding of the lower arch.
Figure 8. (a-e) Near end treatment intra-oral photos. Tooth-coloured fixed appliance being used for treating the lower arch. Rectangular stainless steel archwires in both lower fixed and upper lingual appliance.
a
Figure 4. Upper lingual appliance (Incognito) with 0.012” initial aligning archwire.
June 2013
b
c
Figure 9. (a-c) End of treatment extra-oral views of Case 1.
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Orthodontics
3M, TOP Service) and lower conventional tooth-coloured fixed appliance. Treatment progressed very well and the labially displaced canines were aligned within seven months. A very successful outcome of treatment was achieved. The patient was fitted with upper and lower fixed bonded retainers from canine to canine. In addition, the patient was given vacuum-formed retainers to be worn on a night-time basis.
Case 2 (Figures 12−19)
6.
7.
and development. J Clin Orthod 1982; 16: 735−740. Shpack N, Geron S, Floris I, Davidovitch M, Brosh T, Vardimon AD. Bracket placement in lingual vs labial systems and direct vs indirect bonding. Angle Orthod 2007; 77: 509−517. Buso-Frost L, Fillion D. An overall view of the different laboratory procedures used in conjunction with lingual orthodontics. Semin
8.
9. 10.
11.
a
This patient presented with a Class II division 1 incisor relationship. She was very keen to have orthodontic treatment but was not prepared to wear conventional upper labial arch appliances. With the degree of crowding and transverse discrepancy other invisible appliances, such as Invisalign, b were not going to be an option. The treatment plan involved lower conventional tooth-coloured appliances and upper lingual appliance. The upper lingual fixed appliance was Incognito (3M, TOP Service) which was custom-made to fit the lingual surfaces of the teeth precisely. Treatment was undertaken on a non-extraction approach and progressed very rapidly. An excellent c outcome was achieved within 12 months and upper fixed and removable retainers were fitted.
12.
13.
14.
15.
16.
Conclusion This article has demonstrated the route of development that lingual orthodontic appliances have taken over the d last 30 years. Clearly, improved technology in the construction of the brackets and improved bonding techniques has made the use of the appliance far more user-friendly with predictable results.
Orthod 2006; 12: 203−210. Fillion D. Clinical advantages of the Orapixstraight wire lingual technique. Int Orthod 2010; 8: 125−151. Fillion D. Up-to-date lingual indirect bonding procedure. J Lingual Orthod 1999; 1: 4−8. Geron S. Finishing with lingual appliances, problems and solutions. Semin Orthod 2006; 12: 191−202. Gorman JC, Smith RJ. Comparison of treatment effects with labial and lingual fixed appliances. Am J Orthod Dentofacial Orthop 1991; 99: 202−209. Liang W, Rong Q, Lin J, Xu B. Torque control of maxillary incisors in lingual and labial orthodontics: a 3-dimensional finite element analysis. Am J Orthod Dentofacial Orthop 2009; 135: 316−322. Echarri P. Lingual orthodontics: patient selection and diagnostic considerations. Semin Orthod 2006; 12: 160−166. Van der Veen MH, Attin R, Schwestha-Polly R, Wiechmann D. Caries outcome after orthodontic treatment with fixed appliances: do lingual brackets make a difference? Eur J Oral Sci 2010; 118: 298−303. Hohoff A, Seifert E, Fillion D, Stamm T, Heinecke A, Ehmer U. Speech performance in lingual orthodontic patients measured by sonography and auditive analysis. Am J Orthod Dentofacial Orthop 2003; 123: 146−152. Miyawaki S, Yasuhara M, Koh Y. Discomfort caused by bonded lingual orthodontic appliances in adult patients as examined by retrospective questionnaire. Am J Orthod
a
References 1.
2.
3. 4. 5.
Echarri P. Revisiting the history of lingual b orthodontics: a basis for the future. Semin e Orthod 2006; 12: 153−159. Fujita K. New orthodontic treatment with lingual brackets and mushroom archwire technique. Am J Orthod 1979; 76: 657−675. Geron S. Self-ligating brackets in lingual orthodontics. Semin Orthod 2008; 14: 64−72. McCrostie HE. Lingual orthodontics: the future. Figure 11. (a, b) Before and after occlusal view Semin Orthod 2006: 12: 211−214. Figure 10. (a-e) End of treatment intra-oral views showing complete relief of crowding achieved Kurz C, Swartz ML, Andreiko C. Lingual of Case 1. with a lingual appliance. orthodontics: a status report. Part 2. Research
398 DentalUpdate
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Orthodontics
a
c
b
Figure 12. (a-c) Pre-treatment extra-oral views of Case 2.
a
a
d
b
b
c
e c
d
Figure 13. (a-e) The patient presented with a Class II division 1 incisor relationship with upper and lower moderate to severe crowding.
e Dentofacial Orthop 1999; 115: 83−88. 17. Wu AKY, McGrath C, Wong RWK, Wiechmann D, Rabie ABM. A comparison of pain experience by patients treated with labial and lingual orthodontic appliances. Eur J Orthod 2010; 32: 403−407. 18. Caniklioglu C, Oztürk Y. Patient discomfort: a comparison between lingual and labial fixed appliances. Angle Orthod 2005; 75: 86−91. 19. Wiechmann D, Gerb J, Stamm T, Hohoff A. Prediction of oral discomfort and dysfunction in lingual orthodontics: a preliminary report. Am J
June 2013
Orthod Dentofacial Orthop 2008; 133: 359−364. 20. Stamm T, Hohoff A, Ehmer U. A subjective comparison of two lingual bracket systems. Eur J Orthod 2005; 27: 420−426. 21. Fritz U, Diedrich P, Wiechmann D. Lingual technique − patients’ characteristics, motivation and acceptance. Interpretation of a retrospective survey. J Orofacial Orthop 2002; 63: 227−233. 22. Shum LM, Wong R, Hagg U. Lingual orthodontics − a review. Hong Kong Dent J 2004; 1: 13−20.
Figure 14. (a-e) The lower arch is being aligned with a tooth-coloured lower labial fixed appliance and the upper arch with the lingual appliance (IncognitoTM).
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Orthodontics
a 23. Gorman JC, Hilgers JJ, Smith JR. Lingual orthodontics: a status report. Part 4. Diagnosis and treatment planning. J Clin Orthod 1983; 17: 26−35. 24. Wiechmann D, Rummel V, Thalheim A, Simon J-S, Wiechmann L. Customized brackets and archwires for lingual orthodontic treatment. Am J Orthod Dentofacial Orthop 2003; 124: 593−599.
b
c
e
d
Figure 15. (a-e) The lower arch is aligning well and space is being created for alignment of the LR6. A rectangular NiTi wire is placed in the upper lingual appliance.
Figure 16. The extra-oral view to show the invisible nature of the lingual appliance.
Figure 17. A fixed and removable retainer (Manchester Retainer) is employed to maintain the position of the teeth.
402 DentalUpdate
a
d
b
e
c
Figure 18. (a-e) The post-treatment intra-oral views. Good alignment of the upper and lower arches has been achieved. The patient is due to have new composite restoration placed in the upper labial segment.
Figure 19. Post-operative extra-oral view.
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Ailbhe McMullin David Waring and Ovais Malik
Invisible Orthodontics Part 2: Lingual Appliance Treatment Abstract: The aim of this second article of the three part series is to sum up the current developments in lingual orthodontics. This article attempts to review the development, advantages and disadvantages, bonding techniques, bracket mechanics, patient factors and types of lingual appliance systems available. In addition, the article shows examples of treated cases with lingual appliances. Clinical Relevance: Lingual appliances are a useful addition to the armamentarium of invisible orthodontic appliances, with significant developments over the last few years. Clinicians need to be aware of the advances and predictable results achievable with lingual appliances. Dent Update 2013; 40: 391–402
A review of the literature1 suggests that, as far back as 1726, Fauchard introduced using appliances on the lingual surfaces of teeth. However, it was Fujita2 in the 1970s who is credited with pioneering modern lingual treatment with lingual brackets and ‘mushroom-shaped’ archwires. Interestingly, this came about to address the demands
Ailbhe McMullin, BDentSc(Hons), MFDS RCS(Ire), Specialist Registrar in Orthodontics, University of Manchester Dental Hospital, David T Waring, BChD, MDentSci, MFDS RCS(Eng), MOrth RCS(Ed), FDS(Orth) RCS(Ed), Consultant in Orthodontics, University of Manchester Dental Hospital and Northenden House Orthodontics, Sale Road, Manchester M23 0DF and Ovais H Malik, BDS, MSc(Orth), MFDS RCS(Ed), MOrth RCS(Eng), MOrth RCS(Ed), FDS(Orth) RCS(Eng), Consultant in Orthodontics, University of Manchester Dental Hospital, Salford Royal NHS Foundation Trust, Stott Lane, Manchester M6 8HD and Northenden House Orthodontics, Sale Road, Manchester M23 0DF. June 2013
of martial artists undertaking orthodontic treatment. The poor outcome of completed cases triggered a drop in interest in the 1990s, but with technological advances there has been a recent resurgence in the use of lingual appliances.
Bracket mechanics Since the initial suggestion that brackets could be placed behind the teeth in the 70s, several American orthodontists formed the Lingual Task Force to promote the use of lingual appliances. This has led to the development of numerous lingual appliance systems. Table 1 gives a breakdown of the brackets currently available. Ormco Corporation (Orange, CA, USA) produced one of the first bracket systems following work undertaken by Kurz et al;5 this was placed as an edgewise appliance. As access is difficult and there is a lack of direct visualization of the lingual surfaces, numerous indirect bonding set-up systems have developed as an alternative to direct bonding. Published research has suggested significant improvement in bracket position with reduced torque and rotational errors using an indirect bonding system.6 A high degree of accuracy
can therefore be achieved using these techniques in bracket positioning. The chairside bond-up time is also reduced. Table 2 lists some of the main bracket set-up systems and outlines their main features. Actual bonding protocols have also advanced over the last decade. Previous problems relating to the increased debonding of brackets negatively influenced the lingual technique in the US during the 1980s.9 The standard technique was difficult to employ with bracket positional discrepancies and inaccuracies in finishing. There are both clinical and biomechanical differences between labial and lingual orthodontics. Lingual tooth surfaces have a greater slope than the labial side and a more irregular anatomical form. The built in bracket prescription tends to be expressed later in lingual treatment.10 It is harder to correct rotations due to the small arch perimeter and the decreased interbracket distance. Kurz and Bennett suggest the shorter interbracket distance decreases torque control and leads to a more obtuse interincisal angle and more upright incisors, especially in extraction cases.11 In the horizontal plane, the inter bracket distance is reduced compared to labial orthodontics, which produces less DentalUpdate 391
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Orthodontics
Conventional Brackets1
Ormco 7th Generation Lingual Bracket
Evolved from Kurz lingual bracket design Hooks on bracket help secure the archwire A rhomboid-shaped bite plane helps with overbite reduction, incisor intrusion and aids expansion Optional tube on molar brackets for transpalatal arches
Incognito/iBraces
3D scanning and CAD-CAM technology with prototyping used to generate customized brackets made of a very hard alloy with high gold content Tip and torque prescriptions are individualized Vertical slot with vertical archwire insertion direction A computer-controlled robot bends customized archwires
Self-Ligating Brackets3,4
Forestadent Philippe 2D SL Bracket Forestadent 2D Lingual SL Bracket − 3rd Generation Adenta Evolution LT – 2nd Generation
Wings are closed against the base to hold the archwire Lacks 3D control as there is no slot 4 types − standard, narrow single wing, large twin & three wing
Figure 1. ‘Mushroom-shaped’ archwire.
Options include a T-hook for securing elastic chain, a gingival hook for intermaxillary elastics or a plus bracket to apply individual torque
compounding known difficulties with anterior torque control in lingual appliances. The mushroom archwire formation has an area of weakness between the canines and premolars, which is prone to fracturing. More recently, lingual straightwire techniques have evolved with modifications in the bonding heights and the positioning of canine and premolar attachments to eliminate the use of mushroom loop archwires.8 Brackets are placed as close as possible to the tooth surface, which reduces the slot-tooth distance, improving 3D control of tooth positions. Mechanics are easier with straight archwires and it is suggested that there is improved patient comfort. Table 3 outlines the types of cases which are suitable for lingual therapy, and those that are not. The advantages and disadvantages are listed in Table 4. As with any new technique, there is a learning curve associated with switching from labial to lingual appliance therapy. Access and visualization of the working area are reduced and there is a different range of factors to which to adapt.
One piece bracket with clip opening at the incisal edge Allow archwire insertion from occlusal direction In crowded cases it can be difficult to close all the clips Can accept auxiliary springs for extra torque and tip control Increased maxillary incisor torque, decreased buccolingual thickness and a stronger clip
Ormco Scuzzo/ Passive self-ligating 3D system with interbracket distance maximized Takemoto All brackets feature a hook and a gingivally offset pad for more incisal bracket Bracket (STb) placement STb Light Lingual Full-arch system using very light forces STb Social 6 Used on anterior teeth with minor to moderate crowding or spacing GAC In-Ovation-L Bracket
Twin horizontal slot with interactive clip for ease of opening Minimal buccolingual width and low profile allows for larger archwire perimeter and increased interbracket distance
Gestenco Phantom Bracket
Polyceramic system Rounded margins to improve patient comfort
Table 1. Types of lingual bracket systems.
flexibility in the archwire. Therefore a more flexible wire should be used to compensate for this and allow for physiological tooth movement. A 3D finite element model study12 found identical loads in labial and lingual orthodontics produce very different results − translation and uncontrolled tipping with intrusion, respectively. When retracting incisors it is suggested that one uses mild
392 DentalUpdate
forces and that the root torque is increased. Most bracket systems rely on the use of ‘mushroom-shaped’ archwires with canine, premolar and molar offsets (Figure 1) as their set-up method is based on individualized resin pads to compensate for the differences in tooth thicknesses. This results in particularly the incisor attachments being further from the lingual surfaces,
Patient factors Patients do report problems with lingual appliances, including altered speech, tongue soreness, difficulty maintaining oral hygiene and adherence of food between brackets. Lingual brackets alter the morphology of the lingual surface and the second articulation zone, leading to difficulty with speech performance, in June 2013
© MA Healthcare Ltd. Downloaded from magonlinelibrary.com by 144.082.238.225 on September 11, 2017. Use for licensed purposes only. No other uses without permission. All rights reserved.
Orthodontics
Lab System Set-Up Model?
Mode of Positioning
Advantages
Disadvantages
CLASS System √ Separate metal plates aid anterior/posterior positioning (Custom Lingual Transfer to original model via acrylic caps Appliance Set-up Service)
1st order bends not needed in labial segment as tooth thickness factored in
Multi-step process Errors in transfers cumulative
TARG System Χ Brackets at same distance from incisal/occlusal plane (Torque Silicone/ thermoplastic transfer tray Angulation Reference Guide)
Possible to prescribe torque & angulation for each tooth individually
Many 1st order bends required as thickness of teeth not factored in
BEST System Χ Caliper to measure tooth thickness No need for bends in (Bonding with Built-in compensation for differences in tooth thickness anterior section of Equal Specific wire Thickness)
Archwire bends between canine and premolar, premolar and molar required
LBJ (Lingual Χ Set of 6 anterior, 1 universal posterior jig plus a special ruler Bracket Jig) Transfers Andrews labial prescription to lingual
Limited number of jigs available
TOP (Transfer Optimized Positioning)
√ Virtual target set-up
Allows indirect and direct bracket positioning
TARG Professional used High levels of Slots aligned in virtual archwire plane with height, precision angulation and torque set 1st order adaptation performed manually
Customized brackets with high gold content expensive
KIS System √ All brackets positioned at once (Korean Indirect Bonding Set-Up)
Simpler and faster Allows for bracket height differences
Special model gauge required for precise set-up model
Hiro System √ Full-sized rigid rectangular wire used to aid bracket positioning Individual bracket transfer trays made
No need for 1st order bends in labial segment (customized resin pads)
Initial bond-up appointment longer Need new tray if debond occurs
Orapix System √ Model scanned to create 3D data file (3Dxer) Virtual 3Txer software creates virtual set-up & transfer trays set-up Manually position brackets in trays
Straightwire principles can be used Compatible with any bracket system
Orapix software required by clinician to finalize the set-up Expensive lab costs
Table 2. Overview of bracket set-up systems for lingual appliances.7,8 Favourable Cases for Lingual13
Unfavourable Cases for Lingual13
Mild incisor crowding and anterior deep bite Long uniform lingual tooth surfaces without fillings, crowns or bridges Good periodontal health Keen, compliant patient Patients can adequately open their mouths and extend their necks
Short abraded and irregular lingual surfaces Heavily filled/restored dentitions Limited ability of patient to open his/her mouth Patients with cervical ankylosis/neck problems Incompletely erupted dentitions
Table 3. Favourable and unfavourable cases for lingual appliance treatment. Advantages of Lingual Therapy
Disadvantages of Lingual Therapy
Aesthetic Bracket design can help with bite opening and intrusion of teeth Accurate bracket positioning systems available Lower incidence of white spot lesions compared to labial therapy14 Adaptable − can combine upper lingual with lower labial appliances
Expensive and require laboratory input Access and direct visualization limited for operator Alters speech15 Patient discomfort especially tongue soreness16 Difficulty maintaining oral hygiene Mechanics differ from labial therapy
Table 4. Advantages and disadvantages of lingual appliance treatment.
June 2013
particular ‘s’ and ‘t’ sounds. Both patients and speech professionals rate speech as poorer with lingual appliances, with most but not all overcoming speech issues by debond.15,16 This contrasts with labial appliance patients who report some speech alteration initially which recovers within a month. The onset of pain has been found to be earlier with lingual compared to labial appliances.17 There does, unsurprisingly, seem to be a difference in the areas of discomfort between lingual and labial fixed appliances, with tongue soreness and speech difficulties greater in lingual appliances and cheek and lip soreness greater in labial appliances.18 Tongue soreness, a particularly uncomfortable feature, is often graded as severe and can persist until lingual appliance removal. A significant negative correlation has been established between SNA and SNB angle and the restriction of tongue space DentalUpdate 393
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Orthodontics
with those with SNB less than one deviation below normal values experiencing more severe restriction of the tongue space.19 The newer lingual appliance systems that are custom made to fit an individual lingual tooth surface tend to be able to incorporate a lower profile of bracket. This has been shown to produce fewer tongue restriction problems, speech disturbances and impairments in chewing and biting.20 While much of the published research in lingual orthodontics has concentrated on the bracket mechanics, there has been little assessment of patient factors, although there appears to be increasing interest in the qualitative aspects of this system. Previously, in a patient-based study,21 it was suggested that the lingual technique appealed to a certain patient type, with females accounting for a higher patient uptake (75%), although this is also a widespread finding in labial fixed appliances. Clearly, the aesthetic aspect was the major factor in undertaking treatment with lingual appliances, as 53% of the patients would have refused orthodontic treatment with conventional/ceramic brackets placed labially. The initial irritations were mainly affecting the tongue (65%), but also speech impairment (24%) induced by the lingual appliance. It is generally accepted that placement of a single arch in separate visits rather than bonding of both arches in a single visit assists in patient comfort.22 The ideal malocclusion for lingual appliance treatment is a low angle deep bite case. In addition, Class I or Class II cases with pre-molar extractions are appropriate simple, predictable cases to begin therapy with lingual orthodontics, whereas full pre-molar extractions, posterior crossbites, anterior open bites and increased mandibular plane angle cases are difficult lingual appliance cases.23
Custom-made appliances New lingual bracket systems are continuously being developed including simpler methods of bonding and ligation methods. Using the latest technology in CAD/CAM processes, Weichmann has produced a system (Incognito) that combines low profile customized brackets with an indirect bonding system.24 This has the advantages of: Lower profile of bracket for patient comfort;
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Accurate re-bonding of brackets with a health was satisfactory, despite less then bracket base to fit exactly the tooth surface; desirable hygiene levels. Improved finishing; The aim of treatment was Precise initial placement using a transfer tray; alignment of upper and lower arches with Increased torque control with customized Class 1 incisors and molar relationship. bracket slot. Owing to the severity of crowding in both Indirect bonding requires upper and lower arches, all first premolars excellent technique with adequate moisture were extracted. The treatment plan involved control and effective teamwork. The tooth an upper lingual appliance (Incognito, surface should be appropriately prepared for the bonding, with use of a sand blaster a followed by the recommended bonding technique. Customized brackets have the advantage of requiring less filler/resin to compensate for the lingual surface and, as a result, have a lower profile bracket. A customized approach also allows straightwire mechanics to be used − especially useful in the buccal segments during space closure. The Incognito system provides a series of archwires, which reduces the need for wire bending, which can be especially difficult in lingual orthodontics.
Non-customized appliances
b Lingual appliance brackets have been popularized recently as direct placement non-customized brackets. These have the advantages of being less expensive and can be used for simple alignment of mild crowding cases. Examples include Forestadent Philippe 2D brackets and the STb (Scuzzo/Takemoto) system (Table 1). They can also be prepared for indirect bonding using a transfer jig. As a result of the bracket base being a standard uniform surface, there will be an increase in filler to compensate for the tooth surface and less predictable bonding. There are also the patient factors as discussed previously. These will continue c to develop and produce improved noncustomized bracket systems and pre-formed archwire sequences.
Case 1 (Figures 2−11) This young adult female was concerned about crowding of her upper and lower teeth. She did not want to wear a conventional upper fixed appliance. Intraorally she presented with a mild Class III incisor relationship with severe crowding of her upper arch and moderate crowding of the lower arch. In the upper arch, both the upper canines were excluded from the line of the arch and displaced labially. Periodontal
Figure 2. (a-c) Pre-treatment extra-oral views of Case 1.
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Orthodontics
a
b Figure 5. Alignment stage in the upper arch with 0.018” NiTi archwire.
c
Figure 7. Mid-treatment extra-oral view showing the invisible nature of the upper lingual appliance.
Figure 6. Complete alignment of upper arch being achieved with rectangular NiTi archwire.
d
a
d
b
e e c
Figure 3. (a-e) Intra-oral views of Case 1 showing severe crowding of the upper arch and moderate crowding of the lower arch.
Figure 8. (a-e) Near end treatment intra-oral photos. Tooth-coloured fixed appliance being used for treating the lower arch. Rectangular stainless steel archwires in both lower fixed and upper lingual appliance.
a
Figure 4. Upper lingual appliance (Incognito) with 0.012” initial aligning archwire.
June 2013
b
c
Figure 9. (a-c) End of treatment extra-oral views of Case 1.
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Orthodontics
3M, TOP Service) and lower conventional tooth-coloured fixed appliance. Treatment progressed very well and the labially displaced canines were aligned within seven months. A very successful outcome of treatment was achieved. The patient was fitted with upper and lower fixed bonded retainers from canine to canine. In addition, the patient was given vacuum-formed retainers to be worn on a night-time basis.
Case 2 (Figures 12−19)
6.
7.
and development. J Clin Orthod 1982; 16: 735−740. Shpack N, Geron S, Floris I, Davidovitch M, Brosh T, Vardimon AD. Bracket placement in lingual vs labial systems and direct vs indirect bonding. Angle Orthod 2007; 77: 509−517. Buso-Frost L, Fillion D. An overall view of the different laboratory procedures used in conjunction with lingual orthodontics. Semin
8.
9. 10.
11.
a
This patient presented with a Class II division 1 incisor relationship. She was very keen to have orthodontic treatment but was not prepared to wear conventional upper labial arch appliances. With the degree of crowding and transverse discrepancy other invisible appliances, such as Invisalign, b were not going to be an option. The treatment plan involved lower conventional tooth-coloured appliances and upper lingual appliance. The upper lingual fixed appliance was Incognito (3M, TOP Service) which was custom-made to fit the lingual surfaces of the teeth precisely. Treatment was undertaken on a non-extraction approach and progressed very rapidly. An excellent c outcome was achieved within 12 months and upper fixed and removable retainers were fitted.
12.
13.
14.
15.
16.
Conclusion This article has demonstrated the route of development that lingual orthodontic appliances have taken over the d last 30 years. Clearly, improved technology in the construction of the brackets and improved bonding techniques has made the use of the appliance far more user-friendly with predictable results.
Orthod 2006; 12: 203−210. Fillion D. Clinical advantages of the Orapixstraight wire lingual technique. Int Orthod 2010; 8: 125−151. Fillion D. Up-to-date lingual indirect bonding procedure. J Lingual Orthod 1999; 1: 4−8. Geron S. Finishing with lingual appliances, problems and solutions. Semin Orthod 2006; 12: 191−202. Gorman JC, Smith RJ. Comparison of treatment effects with labial and lingual fixed appliances. Am J Orthod Dentofacial Orthop 1991; 99: 202−209. Liang W, Rong Q, Lin J, Xu B. Torque control of maxillary incisors in lingual and labial orthodontics: a 3-dimensional finite element analysis. Am J Orthod Dentofacial Orthop 2009; 135: 316−322. Echarri P. Lingual orthodontics: patient selection and diagnostic considerations. Semin Orthod 2006; 12: 160−166. Van der Veen MH, Attin R, Schwestha-Polly R, Wiechmann D. Caries outcome after orthodontic treatment with fixed appliances: do lingual brackets make a difference? Eur J Oral Sci 2010; 118: 298−303. Hohoff A, Seifert E, Fillion D, Stamm T, Heinecke A, Ehmer U. Speech performance in lingual orthodontic patients measured by sonography and auditive analysis. Am J Orthod Dentofacial Orthop 2003; 123: 146−152. Miyawaki S, Yasuhara M, Koh Y. Discomfort caused by bonded lingual orthodontic appliances in adult patients as examined by retrospective questionnaire. Am J Orthod
a
References 1.
2.
3. 4. 5.
Echarri P. Revisiting the history of lingual b orthodontics: a basis for the future. Semin e Orthod 2006; 12: 153−159. Fujita K. New orthodontic treatment with lingual brackets and mushroom archwire technique. Am J Orthod 1979; 76: 657−675. Geron S. Self-ligating brackets in lingual orthodontics. Semin Orthod 2008; 14: 64−72. McCrostie HE. Lingual orthodontics: the future. Figure 11. (a, b) Before and after occlusal view Semin Orthod 2006: 12: 211−214. Figure 10. (a-e) End of treatment intra-oral views showing complete relief of crowding achieved Kurz C, Swartz ML, Andreiko C. Lingual of Case 1. with a lingual appliance. orthodontics: a status report. Part 2. Research
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Orthodontics
a
c
b
Figure 12. (a-c) Pre-treatment extra-oral views of Case 2.
a
a
d
b
b
c
e c
d
Figure 13. (a-e) The patient presented with a Class II division 1 incisor relationship with upper and lower moderate to severe crowding.
e Dentofacial Orthop 1999; 115: 83−88. 17. Wu AKY, McGrath C, Wong RWK, Wiechmann D, Rabie ABM. A comparison of pain experience by patients treated with labial and lingual orthodontic appliances. Eur J Orthod 2010; 32: 403−407. 18. Caniklioglu C, Oztürk Y. Patient discomfort: a comparison between lingual and labial fixed appliances. Angle Orthod 2005; 75: 86−91. 19. Wiechmann D, Gerb J, Stamm T, Hohoff A. Prediction of oral discomfort and dysfunction in lingual orthodontics: a preliminary report. Am J
June 2013
Orthod Dentofacial Orthop 2008; 133: 359−364. 20. Stamm T, Hohoff A, Ehmer U. A subjective comparison of two lingual bracket systems. Eur J Orthod 2005; 27: 420−426. 21. Fritz U, Diedrich P, Wiechmann D. Lingual technique − patients’ characteristics, motivation and acceptance. Interpretation of a retrospective survey. J Orofacial Orthop 2002; 63: 227−233. 22. Shum LM, Wong R, Hagg U. Lingual orthodontics − a review. Hong Kong Dent J 2004; 1: 13−20.
Figure 14. (a-e) The lower arch is being aligned with a tooth-coloured lower labial fixed appliance and the upper arch with the lingual appliance (IncognitoTM).
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Orthodontics
a 23. Gorman JC, Hilgers JJ, Smith JR. Lingual orthodontics: a status report. Part 4. Diagnosis and treatment planning. J Clin Orthod 1983; 17: 26−35. 24. Wiechmann D, Rummel V, Thalheim A, Simon J-S, Wiechmann L. Customized brackets and archwires for lingual orthodontic treatment. Am J Orthod Dentofacial Orthop 2003; 124: 593−599.
b
c
e
d
Figure 15. (a-e) The lower arch is aligning well and space is being created for alignment of the LR6. A rectangular NiTi wire is placed in the upper lingual appliance.
Figure 16. The extra-oral view to show the invisible nature of the lingual appliance.
Figure 17. A fixed and removable retainer (Manchester Retainer) is employed to maintain the position of the teeth.
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a
d
b
e
c
Figure 18. (a-e) The post-treatment intra-oral views. Good alignment of the upper and lower arches has been achieved. The patient is due to have new composite restoration placed in the upper labial segment.
Figure 19. Post-operative extra-oral view.
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