- Email: [email protected]
Lingual Orthodontics: Patient Selection and Diagnostic Considerations
Lingual Orthodontics: Patient Selection and Diagnostic Considerations Pablo Echarri Special considerations regarding the diagnosis and treatment planning in lingual orthodontics are presented in this article. The subject is discussed under sections covering general, periodontal, gingival, dental, and skeletal factors. While these are relevant to both labial and lingual techniques, it is essential to be aware of their impact on the lingual technique. Under the umbrella of these groups, special consideration is given to the influence of the restorative status with special reference to the presence of crowns and large restorations, dentoalveolar discrepancies, as well as the influence of vertical, anteroposterior, and transverse features of presenting malocclusions. The application of the lingual technique in cases requiring orthognathic surgery and preprosthetic orthodontics is also discussed. (Semin Orthod 2006;12:160-166.) © 2006 Elsevier Inc. All rights reserved.
ost malocclusions that can be treated by conventional labial techniques can also be treated with lingual orthodontic techniques,1 however, not all patients can be treated with lingual orthodontics, particularly patients with expected low discomfort tolerance. The latest advances in bracket design, new metal alloys for arch wires and new mechanics have not only simplified the technical aspect of lingual orthodontics but have also contributed to a marked reduction in patient discomfort and improved patient cooperation.
M
Favorable Cases ● ● ● ● ● ● ●
Cases with mild incisor crowding and with anterior deep bite Long and uniform lingual tooth surfaces without fillings, crowns, or bridges Good gingival and periodontal health Keen, compliant patient Skeletal Class I pattern Mesocephalic or mild/moderate brachycephalic skeletal pattern Patients who are able to adequately open their mouths and extend their neck
Unfavorable Cases Patient Selection The majority of malocclusions can be treated with lingual orthodontics, but certain cases are more amenable than others.
● ● ● ●
Post Graduate Department of Orthodontics, University of Barcelona, Spain. Address correspondence to Pablo Echarri, DDS, Museu, 6 1o1a, 08912 Badalona, Barcelona, Spain. Phone: 00 34 93 384 47 05; Fax: 00 34 93 464 22 42; E-mail: echarri@ centroladent.com © 2006 Elsevier Inc. All rights reserved. 1073-8746/06/1203-0$30.00/0 doi:10.1053/j.sodo.2006.05.003
160
● ● ●
Dolichocephalic skeletal pattern Maximum anchorage cases, unless treated with micro implants Short, abraded, and irregular lingual tooth surfaces Presence of multiple crowns, bridges, and large restorations Patients with a low level of compliance Patients with limited ability to open the mouth (trismus) Patients with cervical ankylosis or other neck injuries that prevent neck extension
Lingual orthodontics is a technically demanding technique and clinicians need to be particularly selective when establishing the suitability of a
Seminars in Orthodontics, Vol 12, No 3 (September), 2006: pp 160-166
Patient Selection and Diagnostic Considerations
patient for this form of treatment. At the case discussion appointment, it is important to establish what the patient expects from the treatment and to balance these ideas with the orthodontist’s assessment of the realistic goals achievable. The clinician must try to evaluate the patient’s level of cooperation and level of discomfort tolerance. The patient must be made aware of the impact this form of treatment may have on their work situation, with particular regard to speech impediment and appointment times and that chairside time for appointments may be longer than for conventional orthodontic treatment. Cosmetic problems such as stains, discolorations, asymmetries, atypical dental shapes, and gingival esthetics must be identified. These issues should be fully discussed and the patient offered treatment alternatives that may involve interdisciplinary cooperation with other dentists or specialists. As for any orthodontic case the number of teeth present and the integrity of their crowns, roots, and periodontal support must be taken into account. The alveolar bone height must be assessed as well as the thickness of the bone in dentulous and edentulous spaces. The molar malpositions must also be carefully evaluated and possible alternative solutions should be presented to the patient.
Diagnosis Diagnosis and treatment planning is an important issue for all orthodontic treatment techniques and even more so in lingual orthodontics. Essentially it involves establishing an ideal goal and then determining a method of achieving the goal. Diagnostic considerations for lingual orthodontics1,2 can be classified and discussed under the following headings: ● ● ● ● ● ● ● ● ●
General, with particular reference to esthetics Periodontal and gingival Dental, with particular reference to the presence of crowns and large restorations Dentoalveolar discrepancy Vertical skeletal/dental problems Anteroposterior skeletal/dental problems Transverse skeletal/dental problems Surgical cases Preprosthetic cases
161
General Considerations These are the same considerations that apply to labial orthodontics, especially those concerning adult orthodontics. Special consideration should be given to patient selection as listed.
Esthetic Factors One of the most important factors in the treatment of adult patients is their esthetic concerns. The majority of adult patients seek orthodontic treatment with the desire to improve their facial and dental esthetics. Essentially the requirements for achieving a beautiful smile are as follows: ● ● ● ● ● ● ●
Beautiful individual teeth Beautifully aligned and leveled teeth Intact gingival papillae, and leveling of the gingival tissue line Beautiful teeth and gingival exposure in rest position, conversation, and smiling Sufficient dental arch width Sufficient lip support Beautiful lips and perilabial tissues
Arnett3 has emphasized that clinicians should listen to the patient to understand what is really important to them. There are many patient questionnaires available that enable the orthodontist to appreciate and evaluate the patient’s expectations. The patient’s esthetics cannot be adequately observed from the clinician’s conventional position at the side of the chair. These observations must be made from the front as well as the side and at the same height as the patient. It is also very important to standardize the clinical photographs that are used to study and evaluate facial esthetics.4 Apart from the intraoral photographs, the extraoral photographs should include the following: ● ● ● ● ●
Frontal photograph Profile photograph ¾ photograph Photograph of lips at rest, saying, for example, “emma” Photograph of smiling lips, saying, for example, “cheese”
At the clinical examination it is essential to evaluate the position and exposure of the teeth dur-
162
P. Echarri
ing casual conversation. When examining tooth exposure, the dental crown height, incisal edges, axial tips, midlines, cuspid and molar torque, smile line, and left/right symmetry should be carefully observed.
● ●
Periodontal and Gingival Considerations Before starting active orthodontic treatment, the patient should have a healthy periodontium and should be able to maintain a high level of oral hygiene. It may be necessary to refer the patient to a periodontist to achieve and maintain the best possible periodontal status. When establishing a treatment plan the clinician should be mindful of the tooth movements that will occur and their effect on the periodontal and gingival tissues with particular reference to intrusion, extrusion, and space closure. Gingival recession is generally more frequent on the labial tooth surface and consequently the lingual technique is often indicated in patients with a predisposition to gingival recession. With lingual brackets, the risk of gingival inflammation is transferred to the lingual aspect, where bone resorption and gingival recession are generally less frequent. However, once brackets are placed on the lingual surfaces, the risk of possible gingival inflammation may increase due to difficulty with oral hygiene maintenance, proximity of the brackets to the gingival margin, and failure to remove the flash paste (the excess of adhesive that flows toward the gingival sulcus during the indirect bonding process). Gingival inflammation and bunching up of the soft tissues is also observed during closure of a diastema or extraction space. Gingival irritation can be minimized by taking the following precautions: ●
● ●
Bend the lingual bracket hooks when positioning them on the plaster cast, to avoid gingival impingement and reduce tongue irritation. New brackets, such as the Scuzzo/Takemoto bracket (STb) (Ormco Corp, 1332 South Lone Hill Ave, Fairview, NJ 07022), have no hooks, which in turn reduces possible pressure on the gingival tissues and facilitates good oral hygiene. Teach the patient correct oral hygiene techniques. Provide the patient with the necessary elements for good oral hygiene, such as adequate
●
toothbrushes (interproximal toothbrushes), floss threaders, and so on. The use of water picks and mouthwash is also necessary. Carry out prophylaxis in the clinic, especially at each archwire change. The correct adjustment of the bracket transfer tray, the use of liquid adhesives, and the use of the correct quantity of adhesive will minimize the quantity of flash paste and subsequent inflammation. The double-tray system is especially designed to eliminate all the excess of flash paste during the bonding procedure.5 During space closure, carefully maintain and control the effect of tooth movement on the gingival tissues to minimize any possible inflammation.
Dental Considerations Patients with a high risk for caries, with histogenetic or color alterations of the teeth (amelogenesis imperfecta and so on), or with decalcifications can be treated with lingual orthodontics, since the caries and decalcification hazard is transferred to the lingual surface, where the esthetic and therapeutic solutions are always easier to manage, being the nonvisible surfaces of the teeth. The most suitable teeth for lingual orthodontics are those with long and smooth surfaces. Incisors with lingual surfaces shorter than 7 mm should be reconstructed, as well as the mandibular bicuspids with short lingual surfaces. These teeth may be modified by provisional reconstruction of a lingual cusp to facilitate lingual bracket placement. The new STb brackets (Ormco Corp) are reasonably small and can be accommodated on shorter teeth. In exceptional cases, molars with very short lingual surfaces may be bonded on the buccal aspect (Takemoto technique). Some clinicians recommend carrying out a gingivectomy to increase the lingual crown surface height before bonding, but the author does not recommend this procedure. The presence of prominent cingulae, marked marginal ridges, or prominent cusps of Carabelli are unfavorable, and if possible, they should be reduced or recontoured. In certain malocclusions some teeth may show excessive linguoversion (negative torque). This problem can be solved by an initial stage of
Patient Selection and Diagnostic Considerations
selective expansion to facilitate lingual bonding; if indicated, these teeth may be allowed to relapse or moved back to their original position. Crowding with multiple rotations is an indication for using a progressive bonding technique. It is essential to take into account the tooth shape. Rectangular teeth will generally contribute to a pleasing esthetic smile after alignment and rotation control. Triangular teeth may show black gingival triangles, and barrel-shaped teeth will show black occlusal triangles. The latter two issues should be taken into account at the initial treatment planning stage. The prominence of the black triangles may be reduced by interdental stripping and reapproximation or cosmetic fillings and facings, depending on the site and degree of dentoalveolar discrepancy.
Crowns and Restorations Many of the adult cases presenting for lingual orthodontics have mutilated malocclusions, and treatment planning for these cases, particularly when using the lingual technique, requires special consideration. The presence of crowns, bridges, and large restorations impact negatively on achieving good adhesion and these need to be treated with special bonding techniques for plastic, metallic, or porcelain surfaces. It may be necessary to consider the replacement of existing prostheses to achieve a satisfactory postorthodontic occlusion and center line correction. If the existing prosthetic crown anatomy of a tooth is very different from the contralateral tooth, its replacement should be considered. Bridges may be sectioned, taking into account the dental movements that are planned and the anchorage implications. Fractured or microdontic teeth should be provisionally reconstructed before starting the treatment, or immediately after gaining the necessary space, and substituted by definitive crowns at the end of the treatment. Dental restorative replacements should form part of the initial treatment plan and the patient should be appropriately informed.
Dentoalveolar Discrepancy All the methods used in labial orthodontics for the correction of dentoalveolar discrepancies can also be used in lingual therapy. Protrusion, expansion, distalization, stripping, or extrac-
163
tions are all modalities of treatment that can apply to both labial as well as lingual techniques. Currently the general concern with facial esthetics and the trend to maintain anterior lip support is reflected in the preference for a nonextraction approach to orthodontic treatment. This approach is easily and readily accommodated with the lingual technique. During the process of aligning crowded or overlapping maxillary incisors, the appearance of interdental spaces at the gingival margin, referred to as “black triangles,” becomes an esthetic concern for many patients. With the lingual technique, in the absence of labial brackets, the black triangles are readily noticed and for this group of patients, these concerns are often more acute. As with labial techniques, interdental stripping and root paralleling go some way to addressing the problem. Treating malocclusions presenting as bimaxillary protrusion often necessitate the extraction of premolar teeth. While the treatment duration for these types of extraction cases may be longer than for nonextraction cases, with the lingual appliance it is possible to successfully reduce the protrusion and maintain or correct anterior tooth torque.
Vertical Considerations Using the Kurz 7th generation lingual bracket (Ormco Corp), the built-in bite planes on the upper incisor and cuspid brackets will interfere with the occlusion and result in a posterior open bite the extent of which will vary with the degree of initial overbite. The lingual brackets on the maxillary incisors should be bonded to allow a vertical distance of 2 mm from the incisal edge to the bracket, which allows the case to finish with a normal overbite and good posterior occlusion. In cases with high cusps and a severely increased overbite, the distance of the bracket bite plane from the incisal edge may be increased proportionally. The STb (Ormco Corp) brackets do not have a built-in bite plane, and the Stealth bracket (American Orthodontics, 1714 Cambridge Ave, Sheboygm, WI 53082) has a removable bite plane. Management of the posterior open bite created after bracket placement is dependent on the degree of disocclusion. If the molars are separated by approximately 2 mm, the posterior occlusion will be reestablished in approximately
164
P. Echarri
20 to 30 days from bonding. The greater the posterior disocclusion, the more time it takes to restore posterior occlusal contact. If at least three lower incisors make contact with upper bracket bite planes and the posterior disocclusion is not excessive, the protective proprioceptor mechanism within the periodontium will prevent any periodontal trauma. However, if only one lower incisor makes the contact with the upper incisor bracket bite planes (due to incisor irregularity), the patient will feel some discomfort and there is a possibility of periodontal trauma. The same situation may arise if the posterior disocclusion exceeds 3 mm. In such cases it is advisable to build up the occlusal surface of the lower left and right first molars with a light-cure resin or glass ionomer cement to balance the occlusion until the alignment of the mandibular incisors is corrected. As the appliance reduces the overbite, the posterior occlusal buildup should be progressively trimmed. A soft diet is recommended during the first few days. With a combination of molar extrusion and a little incisor intrusion, there will be an increase in the anterior facial vertical dimension. Although this is indicated and desirable in patients with brachycephalic morphology, it is contraindicated in patients who have a predisposition to an increased anterior vertical facial pattern. In such patients, it is necessary to carefully control the vertical molar anchorage by considering occlusal buildup on the second molars, the use of transpalatal bars, space closure as well as minimal use of Class II, III, or vertical intermaxillary elastics. At the treatment planning stage, the clinician should be aware that molar extrusion may contribute to mandibular posterior rotation, which in turn increases the overjet and may lead to excessive lingual tipping of the maxillary incisors. In anterior open bite cases, posterior disocclusion is not an issue at the start of treatment, but as the overbite increases and exceeds 2 mm, then some molar disocclusion may occur.
a Class II problem. Certain patients have a postured bite and therefore it is necessary to deprogram these patients and to carefully evaluate their true centric relationship. Patients may posture their mandible forward and mask a Class II malocclusion. The true initial overjet and overbite should be assessed. An anterior open bite on a Class I skeletal base, although one of the most difficult malocclusions to treat in lingual orthodontics, does not present any problem regarding the initial bonding, irrespective of the overjet. Deep overbite malocclusion on a Class I skeletal base may present with three options, depending on the overjet. ●
●
Normal overjet (Fig 1): If after bonding the maxillary brackets, the posterior disclusion does not exceed 3 mm and there is anterior contact between two or more lower incisors with the same number of maxillary incisor bracket bite planes, it is not necessary to add any molar occlusal buildup. If disclusion exceeds 3 mm, or there is only one incisor contact, then the occlusal surface of the mandibular left and right molars should be built up creating three occlusal contacts (tripodisation). These posterior cement onlays or buildups should be progressively reduced as more incisor occlusal contacts are achieved and the anterior deep bite is corrected. Increased overjet (Fig 2): In such cases there is no anterior contact, but as the maxillary incisors are retracted and the overjet reduced, the
Anteroposterior Discrepancy Skeletal Class I This group is the easiest to treat; however, the clinician must remember that mandibular posterior rotation can transform a Class I case into
Figure 1. In cases with an increased overbite and normal overjet, where the vertical dimension is significantly decreased, it might be necessary to place molar occlusal buildups. (Color version of figure is available online.)
Patient Selection and Diagnostic Considerations
165
exclusively orthodontic treatment. These cases require orthognathic surgery. Dentofacial orthopedics cannot be considered as an option in adult patients.
Transverse Considerations
Figure 2. In cases with an increased overbite and increased overjet, the molar and premolar buildups are used to facilitate maxillary incisor retraction by opening the bite and avoiding possible impingement of the mandibular incisors behind the maxillary incisor brackets. (Color version of figure is available online.)
Posterior cross bites can be treated before starting lingual treatment. The author uses the bonded Hyrax-type palatal expander.1 If the decision is to undertake rapid maxillary expansion before bonding lingual brackets, the impressions for bracket positioning should not be taken until the expansion is completed. The teeth should be maintained in a stable position between the impression taking and bracket bonding to achieve accurate transfer tray positioning. As an alternative, it is possible to use the single-tooth transfer tray technique.6,7
Surgical Cases
●
maxillary brackets can become interposed between the upper and lower teeth, and contribute to accidental debonding, lower incisor tooth wear, or in some cases, because of proprioceptive reflexes, guide the mandible into a more posterior position. This may in turn contribute to the development of temporomandibular joint (TMJ) symptoms; in such cases there is an indication to build up the occlusal surfaces of the left and right first mandibular molars and the first bicuspids. Since the occlusion cannot be stabilized with three contacts (one anterior and two posteriors), as in the case described previously, it should be stabilized with four duly balanced contacts. Decreased overjet (Fig 3): If a patient presents with an anterior cross bite and a deep bite, it is necessary to create four points of occlusal contact by building up the occlusal surface of the posterior teeth; this also facilitates the correction of negative overjet.
The diagnosis and treatment planning is performed in the usual manner; however, it must be borne in mind that many surgeons may refuse to carry out the surgery with lingual brackets bonded in the mouth. Consultation and joint planning with the oral surgeon should be performed before the start of treatment. ●
●
With these cases, the best possible presurgical tooth position should be achieved to minimize the postsurgical orthodontic treatment time. The patient must be consulted on the possibility of bonding labial brackets just before surgery to assist with the postsurgical fixation.
Skeletal Classes II and III If these cases present as relatively mild malocclusions, they can be corrected with extractions or intermaxillary elastics, compensating for the abnormal relationship between the maxilla and mandible. The more severe the skeletal discrepancy, the more compromised will be the end result from
Figure 3. In cases of an increased overbite and anterior cross bite, molar and premolar buildups are used to open the bite and facilitate the correction of the cross bite. (Color version of figure is available online.)
166
P. Echarri
If the lingual appliance is retained, surgical fixation should be performed with miniplates and screws rather than with intermaxillary wires. For intermaxillary fixation, the author prefers to use miniscrew implants placed in the maxilla and mandible at the time of surgery. These may be supplemented with bonded labial buttons.
on both the patient and the orthodontist. In this presentation, the author has highlighted some of the special requirements, with regard to patient selection and diagnostic considerations, which should be taken into account in the treatment of malocclusions using lingual orthodontics.9
Preprosthetic Cases
References
Lingual orthodontic treatment is often indicated in patients requiring preprosthetic tooth movement. The author has established the principles of preprosthetic segmental lingual treatment mechanics, which are rapid, economical, and comfortable for the patient and, therefore, very well accepted.1,7,8 Furthermore, lingual orthodontic techniques can be successfully combined with micro implants in many preprosthetic cases.
1. Echarri P: Lingual Orthodontics. Complete Technique, Step By Step. Barcelona, Nexus Ediciones, 2003 2. Kurz K: Lingual Orthodontics Course Syllabus. Glendora, CA, Ormco, Division of Sybron Co, 1989 3. Arnett GW, McLaughlin RP: Facial and Dental Planning for Orthodontists and ORL Surgeons. Canada, Mosby, 2004 4. Echarri P: Diagn¢stico en Ortodoncia. Tratamiento Multidisciplinario. II Edition. Barcelona, Nexus Ediciones, 2002 5. Echarri P, Kim TW: Double transfer trays for indirect bonding. J Clin Orthod 38:8-13, 2004 6. Hiro T, Takemoto K: Resin core indirect bonding system improvement of lingual orthodontic treatment. J Jpn Orthod Soc 57:83-91, 1998 7. Kim TW, Bae GS, Jaehyung C: New Indirect bonding method for lingual orthodontics. J Clin Orthod 34:348350, 2000 8. Echarri P: Segmental lingual orthodontics in preprosthetic cases. J Clin Orthod 32:716-719, 1988 9. Echarri P: Chapter 13.1. : Segmental Lingual Orthodontics in Multidisciplinary Cases, in Romano R (ed): Lingual Orthodontics. Ontario, BC Decker, 1998
Conclusions Lingual orthodontics is a component of general orthodontics and as such it is subject to all the principles that govern correct patient selection and diagnosis. However, when compared with labial techniques, there are considerable differences in the technique and the clinical demands
ost malocclusions that can be treated by conventional labial techniques can also be treated with lingual orthodontic techniques,1 however, not all patients can be treated with lingual orthodontics, particularly patients with expected low discomfort tolerance. The latest advances in bracket design, new metal alloys for arch wires and new mechanics have not only simplified the technical aspect of lingual orthodontics but have also contributed to a marked reduction in patient discomfort and improved patient cooperation.
M
Favorable Cases ● ● ● ● ● ● ●
Cases with mild incisor crowding and with anterior deep bite Long and uniform lingual tooth surfaces without fillings, crowns, or bridges Good gingival and periodontal health Keen, compliant patient Skeletal Class I pattern Mesocephalic or mild/moderate brachycephalic skeletal pattern Patients who are able to adequately open their mouths and extend their neck
Unfavorable Cases Patient Selection The majority of malocclusions can be treated with lingual orthodontics, but certain cases are more amenable than others.
● ● ● ●
Post Graduate Department of Orthodontics, University of Barcelona, Spain. Address correspondence to Pablo Echarri, DDS, Museu, 6 1o1a, 08912 Badalona, Barcelona, Spain. Phone: 00 34 93 384 47 05; Fax: 00 34 93 464 22 42; E-mail: echarri@ centroladent.com © 2006 Elsevier Inc. All rights reserved. 1073-8746/06/1203-0$30.00/0 doi:10.1053/j.sodo.2006.05.003
160
● ● ●
Dolichocephalic skeletal pattern Maximum anchorage cases, unless treated with micro implants Short, abraded, and irregular lingual tooth surfaces Presence of multiple crowns, bridges, and large restorations Patients with a low level of compliance Patients with limited ability to open the mouth (trismus) Patients with cervical ankylosis or other neck injuries that prevent neck extension
Lingual orthodontics is a technically demanding technique and clinicians need to be particularly selective when establishing the suitability of a
Seminars in Orthodontics, Vol 12, No 3 (September), 2006: pp 160-166
Patient Selection and Diagnostic Considerations
patient for this form of treatment. At the case discussion appointment, it is important to establish what the patient expects from the treatment and to balance these ideas with the orthodontist’s assessment of the realistic goals achievable. The clinician must try to evaluate the patient’s level of cooperation and level of discomfort tolerance. The patient must be made aware of the impact this form of treatment may have on their work situation, with particular regard to speech impediment and appointment times and that chairside time for appointments may be longer than for conventional orthodontic treatment. Cosmetic problems such as stains, discolorations, asymmetries, atypical dental shapes, and gingival esthetics must be identified. These issues should be fully discussed and the patient offered treatment alternatives that may involve interdisciplinary cooperation with other dentists or specialists. As for any orthodontic case the number of teeth present and the integrity of their crowns, roots, and periodontal support must be taken into account. The alveolar bone height must be assessed as well as the thickness of the bone in dentulous and edentulous spaces. The molar malpositions must also be carefully evaluated and possible alternative solutions should be presented to the patient.
Diagnosis Diagnosis and treatment planning is an important issue for all orthodontic treatment techniques and even more so in lingual orthodontics. Essentially it involves establishing an ideal goal and then determining a method of achieving the goal. Diagnostic considerations for lingual orthodontics1,2 can be classified and discussed under the following headings: ● ● ● ● ● ● ● ● ●
General, with particular reference to esthetics Periodontal and gingival Dental, with particular reference to the presence of crowns and large restorations Dentoalveolar discrepancy Vertical skeletal/dental problems Anteroposterior skeletal/dental problems Transverse skeletal/dental problems Surgical cases Preprosthetic cases
161
General Considerations These are the same considerations that apply to labial orthodontics, especially those concerning adult orthodontics. Special consideration should be given to patient selection as listed.
Esthetic Factors One of the most important factors in the treatment of adult patients is their esthetic concerns. The majority of adult patients seek orthodontic treatment with the desire to improve their facial and dental esthetics. Essentially the requirements for achieving a beautiful smile are as follows: ● ● ● ● ● ● ●
Beautiful individual teeth Beautifully aligned and leveled teeth Intact gingival papillae, and leveling of the gingival tissue line Beautiful teeth and gingival exposure in rest position, conversation, and smiling Sufficient dental arch width Sufficient lip support Beautiful lips and perilabial tissues
Arnett3 has emphasized that clinicians should listen to the patient to understand what is really important to them. There are many patient questionnaires available that enable the orthodontist to appreciate and evaluate the patient’s expectations. The patient’s esthetics cannot be adequately observed from the clinician’s conventional position at the side of the chair. These observations must be made from the front as well as the side and at the same height as the patient. It is also very important to standardize the clinical photographs that are used to study and evaluate facial esthetics.4 Apart from the intraoral photographs, the extraoral photographs should include the following: ● ● ● ● ●
Frontal photograph Profile photograph ¾ photograph Photograph of lips at rest, saying, for example, “emma” Photograph of smiling lips, saying, for example, “cheese”
At the clinical examination it is essential to evaluate the position and exposure of the teeth dur-
162
P. Echarri
ing casual conversation. When examining tooth exposure, the dental crown height, incisal edges, axial tips, midlines, cuspid and molar torque, smile line, and left/right symmetry should be carefully observed.
● ●
Periodontal and Gingival Considerations Before starting active orthodontic treatment, the patient should have a healthy periodontium and should be able to maintain a high level of oral hygiene. It may be necessary to refer the patient to a periodontist to achieve and maintain the best possible periodontal status. When establishing a treatment plan the clinician should be mindful of the tooth movements that will occur and their effect on the periodontal and gingival tissues with particular reference to intrusion, extrusion, and space closure. Gingival recession is generally more frequent on the labial tooth surface and consequently the lingual technique is often indicated in patients with a predisposition to gingival recession. With lingual brackets, the risk of gingival inflammation is transferred to the lingual aspect, where bone resorption and gingival recession are generally less frequent. However, once brackets are placed on the lingual surfaces, the risk of possible gingival inflammation may increase due to difficulty with oral hygiene maintenance, proximity of the brackets to the gingival margin, and failure to remove the flash paste (the excess of adhesive that flows toward the gingival sulcus during the indirect bonding process). Gingival inflammation and bunching up of the soft tissues is also observed during closure of a diastema or extraction space. Gingival irritation can be minimized by taking the following precautions: ●
● ●
Bend the lingual bracket hooks when positioning them on the plaster cast, to avoid gingival impingement and reduce tongue irritation. New brackets, such as the Scuzzo/Takemoto bracket (STb) (Ormco Corp, 1332 South Lone Hill Ave, Fairview, NJ 07022), have no hooks, which in turn reduces possible pressure on the gingival tissues and facilitates good oral hygiene. Teach the patient correct oral hygiene techniques. Provide the patient with the necessary elements for good oral hygiene, such as adequate
●
toothbrushes (interproximal toothbrushes), floss threaders, and so on. The use of water picks and mouthwash is also necessary. Carry out prophylaxis in the clinic, especially at each archwire change. The correct adjustment of the bracket transfer tray, the use of liquid adhesives, and the use of the correct quantity of adhesive will minimize the quantity of flash paste and subsequent inflammation. The double-tray system is especially designed to eliminate all the excess of flash paste during the bonding procedure.5 During space closure, carefully maintain and control the effect of tooth movement on the gingival tissues to minimize any possible inflammation.
Dental Considerations Patients with a high risk for caries, with histogenetic or color alterations of the teeth (amelogenesis imperfecta and so on), or with decalcifications can be treated with lingual orthodontics, since the caries and decalcification hazard is transferred to the lingual surface, where the esthetic and therapeutic solutions are always easier to manage, being the nonvisible surfaces of the teeth. The most suitable teeth for lingual orthodontics are those with long and smooth surfaces. Incisors with lingual surfaces shorter than 7 mm should be reconstructed, as well as the mandibular bicuspids with short lingual surfaces. These teeth may be modified by provisional reconstruction of a lingual cusp to facilitate lingual bracket placement. The new STb brackets (Ormco Corp) are reasonably small and can be accommodated on shorter teeth. In exceptional cases, molars with very short lingual surfaces may be bonded on the buccal aspect (Takemoto technique). Some clinicians recommend carrying out a gingivectomy to increase the lingual crown surface height before bonding, but the author does not recommend this procedure. The presence of prominent cingulae, marked marginal ridges, or prominent cusps of Carabelli are unfavorable, and if possible, they should be reduced or recontoured. In certain malocclusions some teeth may show excessive linguoversion (negative torque). This problem can be solved by an initial stage of
Patient Selection and Diagnostic Considerations
selective expansion to facilitate lingual bonding; if indicated, these teeth may be allowed to relapse or moved back to their original position. Crowding with multiple rotations is an indication for using a progressive bonding technique. It is essential to take into account the tooth shape. Rectangular teeth will generally contribute to a pleasing esthetic smile after alignment and rotation control. Triangular teeth may show black gingival triangles, and barrel-shaped teeth will show black occlusal triangles. The latter two issues should be taken into account at the initial treatment planning stage. The prominence of the black triangles may be reduced by interdental stripping and reapproximation or cosmetic fillings and facings, depending on the site and degree of dentoalveolar discrepancy.
Crowns and Restorations Many of the adult cases presenting for lingual orthodontics have mutilated malocclusions, and treatment planning for these cases, particularly when using the lingual technique, requires special consideration. The presence of crowns, bridges, and large restorations impact negatively on achieving good adhesion and these need to be treated with special bonding techniques for plastic, metallic, or porcelain surfaces. It may be necessary to consider the replacement of existing prostheses to achieve a satisfactory postorthodontic occlusion and center line correction. If the existing prosthetic crown anatomy of a tooth is very different from the contralateral tooth, its replacement should be considered. Bridges may be sectioned, taking into account the dental movements that are planned and the anchorage implications. Fractured or microdontic teeth should be provisionally reconstructed before starting the treatment, or immediately after gaining the necessary space, and substituted by definitive crowns at the end of the treatment. Dental restorative replacements should form part of the initial treatment plan and the patient should be appropriately informed.
Dentoalveolar Discrepancy All the methods used in labial orthodontics for the correction of dentoalveolar discrepancies can also be used in lingual therapy. Protrusion, expansion, distalization, stripping, or extrac-
163
tions are all modalities of treatment that can apply to both labial as well as lingual techniques. Currently the general concern with facial esthetics and the trend to maintain anterior lip support is reflected in the preference for a nonextraction approach to orthodontic treatment. This approach is easily and readily accommodated with the lingual technique. During the process of aligning crowded or overlapping maxillary incisors, the appearance of interdental spaces at the gingival margin, referred to as “black triangles,” becomes an esthetic concern for many patients. With the lingual technique, in the absence of labial brackets, the black triangles are readily noticed and for this group of patients, these concerns are often more acute. As with labial techniques, interdental stripping and root paralleling go some way to addressing the problem. Treating malocclusions presenting as bimaxillary protrusion often necessitate the extraction of premolar teeth. While the treatment duration for these types of extraction cases may be longer than for nonextraction cases, with the lingual appliance it is possible to successfully reduce the protrusion and maintain or correct anterior tooth torque.
Vertical Considerations Using the Kurz 7th generation lingual bracket (Ormco Corp), the built-in bite planes on the upper incisor and cuspid brackets will interfere with the occlusion and result in a posterior open bite the extent of which will vary with the degree of initial overbite. The lingual brackets on the maxillary incisors should be bonded to allow a vertical distance of 2 mm from the incisal edge to the bracket, which allows the case to finish with a normal overbite and good posterior occlusion. In cases with high cusps and a severely increased overbite, the distance of the bracket bite plane from the incisal edge may be increased proportionally. The STb (Ormco Corp) brackets do not have a built-in bite plane, and the Stealth bracket (American Orthodontics, 1714 Cambridge Ave, Sheboygm, WI 53082) has a removable bite plane. Management of the posterior open bite created after bracket placement is dependent on the degree of disocclusion. If the molars are separated by approximately 2 mm, the posterior occlusion will be reestablished in approximately
164
P. Echarri
20 to 30 days from bonding. The greater the posterior disocclusion, the more time it takes to restore posterior occlusal contact. If at least three lower incisors make contact with upper bracket bite planes and the posterior disocclusion is not excessive, the protective proprioceptor mechanism within the periodontium will prevent any periodontal trauma. However, if only one lower incisor makes the contact with the upper incisor bracket bite planes (due to incisor irregularity), the patient will feel some discomfort and there is a possibility of periodontal trauma. The same situation may arise if the posterior disocclusion exceeds 3 mm. In such cases it is advisable to build up the occlusal surface of the lower left and right first molars with a light-cure resin or glass ionomer cement to balance the occlusion until the alignment of the mandibular incisors is corrected. As the appliance reduces the overbite, the posterior occlusal buildup should be progressively trimmed. A soft diet is recommended during the first few days. With a combination of molar extrusion and a little incisor intrusion, there will be an increase in the anterior facial vertical dimension. Although this is indicated and desirable in patients with brachycephalic morphology, it is contraindicated in patients who have a predisposition to an increased anterior vertical facial pattern. In such patients, it is necessary to carefully control the vertical molar anchorage by considering occlusal buildup on the second molars, the use of transpalatal bars, space closure as well as minimal use of Class II, III, or vertical intermaxillary elastics. At the treatment planning stage, the clinician should be aware that molar extrusion may contribute to mandibular posterior rotation, which in turn increases the overjet and may lead to excessive lingual tipping of the maxillary incisors. In anterior open bite cases, posterior disocclusion is not an issue at the start of treatment, but as the overbite increases and exceeds 2 mm, then some molar disocclusion may occur.
a Class II problem. Certain patients have a postured bite and therefore it is necessary to deprogram these patients and to carefully evaluate their true centric relationship. Patients may posture their mandible forward and mask a Class II malocclusion. The true initial overjet and overbite should be assessed. An anterior open bite on a Class I skeletal base, although one of the most difficult malocclusions to treat in lingual orthodontics, does not present any problem regarding the initial bonding, irrespective of the overjet. Deep overbite malocclusion on a Class I skeletal base may present with three options, depending on the overjet. ●
●
Normal overjet (Fig 1): If after bonding the maxillary brackets, the posterior disclusion does not exceed 3 mm and there is anterior contact between two or more lower incisors with the same number of maxillary incisor bracket bite planes, it is not necessary to add any molar occlusal buildup. If disclusion exceeds 3 mm, or there is only one incisor contact, then the occlusal surface of the mandibular left and right molars should be built up creating three occlusal contacts (tripodisation). These posterior cement onlays or buildups should be progressively reduced as more incisor occlusal contacts are achieved and the anterior deep bite is corrected. Increased overjet (Fig 2): In such cases there is no anterior contact, but as the maxillary incisors are retracted and the overjet reduced, the
Anteroposterior Discrepancy Skeletal Class I This group is the easiest to treat; however, the clinician must remember that mandibular posterior rotation can transform a Class I case into
Figure 1. In cases with an increased overbite and normal overjet, where the vertical dimension is significantly decreased, it might be necessary to place molar occlusal buildups. (Color version of figure is available online.)
Patient Selection and Diagnostic Considerations
165
exclusively orthodontic treatment. These cases require orthognathic surgery. Dentofacial orthopedics cannot be considered as an option in adult patients.
Transverse Considerations
Figure 2. In cases with an increased overbite and increased overjet, the molar and premolar buildups are used to facilitate maxillary incisor retraction by opening the bite and avoiding possible impingement of the mandibular incisors behind the maxillary incisor brackets. (Color version of figure is available online.)
Posterior cross bites can be treated before starting lingual treatment. The author uses the bonded Hyrax-type palatal expander.1 If the decision is to undertake rapid maxillary expansion before bonding lingual brackets, the impressions for bracket positioning should not be taken until the expansion is completed. The teeth should be maintained in a stable position between the impression taking and bracket bonding to achieve accurate transfer tray positioning. As an alternative, it is possible to use the single-tooth transfer tray technique.6,7
Surgical Cases
●
maxillary brackets can become interposed between the upper and lower teeth, and contribute to accidental debonding, lower incisor tooth wear, or in some cases, because of proprioceptive reflexes, guide the mandible into a more posterior position. This may in turn contribute to the development of temporomandibular joint (TMJ) symptoms; in such cases there is an indication to build up the occlusal surfaces of the left and right first mandibular molars and the first bicuspids. Since the occlusion cannot be stabilized with three contacts (one anterior and two posteriors), as in the case described previously, it should be stabilized with four duly balanced contacts. Decreased overjet (Fig 3): If a patient presents with an anterior cross bite and a deep bite, it is necessary to create four points of occlusal contact by building up the occlusal surface of the posterior teeth; this also facilitates the correction of negative overjet.
The diagnosis and treatment planning is performed in the usual manner; however, it must be borne in mind that many surgeons may refuse to carry out the surgery with lingual brackets bonded in the mouth. Consultation and joint planning with the oral surgeon should be performed before the start of treatment. ●
●
With these cases, the best possible presurgical tooth position should be achieved to minimize the postsurgical orthodontic treatment time. The patient must be consulted on the possibility of bonding labial brackets just before surgery to assist with the postsurgical fixation.
Skeletal Classes II and III If these cases present as relatively mild malocclusions, they can be corrected with extractions or intermaxillary elastics, compensating for the abnormal relationship between the maxilla and mandible. The more severe the skeletal discrepancy, the more compromised will be the end result from
Figure 3. In cases of an increased overbite and anterior cross bite, molar and premolar buildups are used to open the bite and facilitate the correction of the cross bite. (Color version of figure is available online.)
166
P. Echarri
If the lingual appliance is retained, surgical fixation should be performed with miniplates and screws rather than with intermaxillary wires. For intermaxillary fixation, the author prefers to use miniscrew implants placed in the maxilla and mandible at the time of surgery. These may be supplemented with bonded labial buttons.
on both the patient and the orthodontist. In this presentation, the author has highlighted some of the special requirements, with regard to patient selection and diagnostic considerations, which should be taken into account in the treatment of malocclusions using lingual orthodontics.9
Preprosthetic Cases
References
Lingual orthodontic treatment is often indicated in patients requiring preprosthetic tooth movement. The author has established the principles of preprosthetic segmental lingual treatment mechanics, which are rapid, economical, and comfortable for the patient and, therefore, very well accepted.1,7,8 Furthermore, lingual orthodontic techniques can be successfully combined with micro implants in many preprosthetic cases.
1. Echarri P: Lingual Orthodontics. Complete Technique, Step By Step. Barcelona, Nexus Ediciones, 2003 2. Kurz K: Lingual Orthodontics Course Syllabus. Glendora, CA, Ormco, Division of Sybron Co, 1989 3. Arnett GW, McLaughlin RP: Facial and Dental Planning for Orthodontists and ORL Surgeons. Canada, Mosby, 2004 4. Echarri P: Diagn¢stico en Ortodoncia. Tratamiento Multidisciplinario. II Edition. Barcelona, Nexus Ediciones, 2002 5. Echarri P, Kim TW: Double transfer trays for indirect bonding. J Clin Orthod 38:8-13, 2004 6. Hiro T, Takemoto K: Resin core indirect bonding system improvement of lingual orthodontic treatment. J Jpn Orthod Soc 57:83-91, 1998 7. Kim TW, Bae GS, Jaehyung C: New Indirect bonding method for lingual orthodontics. J Clin Orthod 34:348350, 2000 8. Echarri P: Segmental lingual orthodontics in preprosthetic cases. J Clin Orthod 32:716-719, 1988 9. Echarri P: Chapter 13.1. : Segmental Lingual Orthodontics in Multidisciplinary Cases, in Romano R (ed): Lingual Orthodontics. Ontario, BC Decker, 1998
Conclusions Lingual orthodontics is a component of general orthodontics and as such it is subject to all the principles that govern correct patient selection and diagnosis. However, when compared with labial techniques, there are considerable differences in the technique and the clinical demands