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Orthodontic treatment for a patient with hypodontia involving the maxillary lateral incisors

2011; Elsevier BV; Volume: 139; Issue: 5 Linguagem: Inglês

10.1016/j.ajodo.2009.10.042

1097-6752

Saud A. Al-Anezi,

Oral and Maxillofacial Pathology

Developmental absence of maxillary lateral incisors is not uncommon in orthodontic patients. Treatment depends on a number of factors, including skeletal pattern, type of malocclusion, overjet, and the shape and color of the canines. Management can be broadly divided into space closure, space opening or redistribution, and prosthetic replacement. The purpose of this article was to report the treatment of a girl with an Angle Class I malocclusion with missing maxillary lateral incisors and severe crowding in the mandibular labial segment. Treatment included preadjusted fixed appliances, extraction of the mandibular first premolars, and space closure of the maxillary labial segment space with the canines substituted for the maxillary lateral incisors. Developmental absence of maxillary lateral incisors is not uncommon in orthodontic patients. Treatment depends on a number of factors, including skeletal pattern, type of malocclusion, overjet, and the shape and color of the canines. Management can be broadly divided into space closure, space opening or redistribution, and prosthetic replacement. The purpose of this article was to report the treatment of a girl with an Angle Class I malocclusion with missing maxillary lateral incisors and severe crowding in the mandibular labial segment. Treatment included preadjusted fixed appliances, extraction of the mandibular first premolars, and space closure of the maxillary labial segment space with the canines substituted for the maxillary lateral incisors. Hypodontia is the developmental absence of at least 1 tooth.1Goodman J.R. Jones S.P. Hobkirk J.A. King P.A. Hypodontia: clinical features and the management of mild to moderate hypodontia.Dent Update. 1994; 21: 381-384Google Scholar The incidence of missing maxillary lateral incisors is 1% to 2% in white populations.2Zilberman Y. Cohen B. Becker A. Familial trends in palatal canines, anomalous lateral incisors, and related phenomena.Eur J Orthod. 1990; 12: 135-139Crossref PubMed Scopus (116) Google Scholar The etiology of hypodontia can be genetically determined and arises as a familial condition. The condition is more common bilaterally than unilaterally and can be associated with impacted maxillary canines. This condition causes several problems, including unsightly spacing between the anterior teeth, and drifting and rotation of the central incisors and the canines. In unilateral cases, these effects are asymmetric and can result in a midline shift. Furthermore, dental health problems might arise because of food impaction as a result of tipped teeth. A suspected absence of the maxillary permanent lateral incisor should be confirmed radiographically if the tooth has failed to erupt by the age of 9 years, or within 6 months of the contralateral tooth.3Isaacson K.G. Thom A.R. Horner K. Whaites E. Orthodontic radiographs: guidelines. British Orthodontic Society, London, United Kingdom2008Google Scholar The management of missing maxillary lateral incisors often needs a multidisciplinary approach and can be broadly divided into space closure, space opening, and space redistribution. A number of factors should be considered in the management of such patients.4Carter N.E. Gillgrass T.J. Hobson R.S. Jepson N. Meechan J.G. Nohl F.S. et al.The interdisciplinary management of hypodontia: orthodontics.Br Dent J. 2003; 194: 361-366Crossref PubMed Scopus (50) Google Scholar These include patient factors: age, medical history, motivation, and attitude toward orthodontic treatment. Other factors include skeletal pattern, type of malocclusion, number of missing teeth, size, shape, and the gingival margin of the maxillary canines. In this case report, an adolescent girl complained of the appearance of her maxillary anterior teeth because of developmentally absent lateral incisors and crowding in the mandibular arch. This girl, aged 14.6 years, had an Angle Class І malocclusion on a mild Class ІІ skeletal pattern with reduced Frankfort mandibular plane angle and lower anterior face height. There was no facial asymmetry, and the lips were competent with a low smile line (Fig 1). In the intraoral assessment, her oral hygiene was fair but needed improvement before orthodontic treatment. The erupted teeth were as follows.Tabled 16 5 4 3 11 3 4 5 67 6 5 4 3 2 11 2 3 4 5 6 7 Open table in a new tab Both maxillary and mandibular left first molars were hypoplastic but not carious. Fissure sealants were present occlusally in all first molars. From the history and clinical examination, these teeth did not cause any problem to the patient (eg, sensitivity), and the long-term prognosis was good. The maxillary arch had spacing, whereas the mandibular arch was severely crowded. Overjet was 5.5 mm, and overbite was deep with palatal impingement. The molar relationship was Class I on both sides, and the incisor relationship was Class II Division 2 (Fig 2). The maxillary canines were in crossbite. Furthermore, the maxillary left central incisor and the maxillary right second premolar were rotated; these might cause some concern in terms of stability and risk of relapse. The mandibular left second premolar was partially erupted. In addition, space analysis showed that the space requirement in the mandibular arch was 14 mm. The dental panoramic tomogram confirmed the presence of all permanent teeth except the maxillary lateral incisors and the third molars. Teeth yet to erupt were the maxillary and mandibular second molars and the mandibular third molars (Fig 3). Root length and morphology appeared normal. In the cephalometric assessment (Fig 4 and Table). The ANB value was 3°, which suggested a Class І skeletal pattern. However, by applying the Eastman correction (SN/Max 10°), the corrected ANB was 5°, which indicated a mild Class ІІ skeletal pattern.5Mills J.R. The application and importance of cephalometry in orthodontic treatment.Orthodontist. 1970; 2: 32-47PubMed Google Scholar The mandibular incisor inclination was retroclined at 80°. The maxillary left central incisor was proclined at 118°, and the maxillary right central incisor appeared retroclined. The lower anterior face height was reduced, and the mandibular incisor to the APo line was within normal limits. The lower lip was positioned posteriorly to the E-line.Fig 4Pretreatment cephalometric tracing.View Large Image Figure ViewerDownload Hi-res image Download (PPT)TableCephalometric analysisVariablePretreatmentNormal∗Normal values for white subjects taken from Houston et al.13PredebondOverall changeSNA86°82° ± 3°85°−1°SNB83°79° ± 3°82°−1°ANB3°3° ± 1°3°0Maxillary incisor to maxillary plane angle118°108° ± 5°113°−5°Mandibular incisor to mandibular plane angle80°92° ± 5°90°−10°Interincisal angle142°133° ± 10°130°−12°Maxillary-mandibular planes angle20°27° ± 5°23°3°Face height ratio52%55%54%2%Mandibular incisor to APo line−2 mm0–2 mm1 mm3 mmLower lip to Ricketts' E-plane−4 mm−2 mm−1 mm3 mmSNA, Sella–nasion–A-point; SNB, sella–nasion–B-point; ANB, A-point–nasion–B-point; APo, A-point–pogonion.∗ Normal values for white subjects taken from Houston et al.13Houston W.J. Stephens C.D. Tulley W.J. A textbook of orthodontics. United Kingdom, Wright, Oxford1992Google Scholar Open table in a new tab SNA, Sella–nasion–A-point; SNB, sella–nasion–B-point; ANB, A-point–nasion–B-point; APo, A-point–pogonion. The malocclusion was complicated by the developmentally absent maxillary lateral incisors, increased and complete overbite, severe crowding in the mandibular arch and the crossbite involving the maxillary canines. The genetically inherited skeletal pattern and the reduced vertical proportions contributed to the malocclusion. In addition, the high lower lip line contributed to the retroclination of the maxillary right central incisor. The treatment objectives included (1) accept the patient's profile, (2) relieve the crowding in the mandibular labial segment, (3) level and align, (4) reduce the overbite, (5) reduce the overjet and correct the crossbite involving the maxillary canines, (6) close the maxillary spacing, (7) substitute the maxillary canines as lateral incisors, and (8) retain. The decision to close the space in the maxillary labial segment was based on the fact that the patient had a mild Class ІІ skeletal pattern with a slightly increased overjet. In addition, the shape and the color of the maxillary canines were considered favorable in terms of esthetics. Restorative treatment was planned to reshape the maxillary canines and camouflage their appearance. The severity of crowding in the mandibular labial segment indicated the necessity to extract the mandibular left and right first premolars. The patient was treated with a fixed appliance with a 0.022-in slot McLaughlin, Bennett, Trevisi (MBT) prescription.6Bennett J.C. McLaughlin R.P. Orthodontic management of the dentition with the preadjusted appliance. Mosby, St Louis2001Google Scholar The maxillary fixed retainer was chosen to minimize the risk of relapse of the severely rotated maxillary left central incisor. In addition, the patient was provided with maxillary and mandibular Essix retainers (DENTSPLY Limited, Surrey, United Kingdom). from the first molar to the first molar to wear at night only. As an alternative, space opening in the maxillary arch and replacement of the maxillary lateral incisors with implants might have been considered. However, the severity of the mandibular arch crowding necessitated the extraction of the mandibular premolars. As a consequence, there was a need to compensate for the extractions in the mandibular arch with extractions in the maxillary arch, because the malocclusion was essentially Class I. Because the maxillary lateral incisors were developmentally absent, further extractions in the maxillary arch were not required. In addition, the color and morphology of the maxillary canines were encouraging to use them as lateral incisors. The treatment progressed well without major complications. The patient was cooperative, and her oral hygiene improved as the treatment progressed. Overbite reduction started slowly at the beginning of treatment (Fig 5). The banding of the mandibular second molars helped in controlling the overbite. The use of Class ІІ intermaxillary traction helped to reduce the overjet and close the maxillary space. This also had the effect of extruding the mandibular molars and ultimately helped with the overbite reduction. A reverse curve of Spee was placed in the mandibular archwire to further reduce the overbite.7Parker C.D. Nanda R.S. Currier G.F. Skeletal and dental changes associated with the treatment of deep overbite malocclusion.Am J Orthod Dentofacial Orthop. 1995; 107: 382-393Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar This was necessary before the space closure phase of treatment. During treatment, space closure in the mandibular arch progressed well. However, space closure in the mandibular right quadrant was slow. Radiographic assessment showed that the roots of the mandibular right canine and the second premolar were too close together. This was rectified with bracket repositioning and artistic bends in the archwire as the space was closed. The duration of active treatment was 23 months, and the treatment objectives were achieved. The patient's profile was maintained (Fig 6). At the end of treatment, the maxillary labial segment space was closed by movement of the canines mesially. The incisor relationship was Class I. The overjet at the end of treatment was 2 mm. The mandibular crowding was relieved, and the mandibular incisors were aligned (Fig 7). The overbite was dramatically reduced. The bilateral crossbites involving the mandibular canines were eliminated, and the dental midlines were coincident.Fig 7Posttreatment models.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The decision to close the space was based on a number of factors. Firstly, the patient had a Class II skeletal pattern; hence, space opening to place implants might worsen her profile. Furthermore, there was a slight increase in the overjet; therefore, space closure would also lead to a reduction in the overjet. The smile line was low, so that the discrepancies in the gingival margins of the canines and the central incisors would not be apparent. Another important advantage of space closure was that the gingival tissue and interdental papillae would change in synchrony with the patient's own teeth over her lifetime.8Rosa M. Zachrisson B.U. Integrating esthetic dentistry and space closure in patients missing maxillary lateral incisors.J Clin Orthod. 2001; 35: 221-234PubMed Google Scholar However, there are potential disadvantages with the space-closure approach. Moving the canine mesially next to the central incisor might not be esthetically pleasing, since the cusps are prominent and these teeth are naturally darker than the lateral incisor. In this patient, the morphology and the color of the maxillary canines were encouraging. A restorative camouflage consisting of careful grinding, composite buildup, and bleaching was an integral part of the treatment plan. Nonetheless, the patient was satisfied with the outcome of the grinding and reshaping of the canines without the need for composite buildup or bleaching. Another potential disadvantage is that placing the first premolar in the position previously occupied by the canine might result in heavy occlusal forces, since canine-protected occlusion is not possible. The roots of the first premolars are thinner and smaller; therefore, there is a concern of potential damage to the periodontal health. However, a long-term study failed to demonstrate this effect, and some studies are in favor of the space-closure option.9Robertsson S. Mohlin B. The congenitally missing upper lateral incisor. A retrospective study of orthodontic space closure versus restorative treatment.Eur J Orthod. 2000; 22: 697-710Crossref PubMed Scopus (209) Google Scholar Finally, there is a risk of space reopening in any space-closure treatment. In this patient, because of the rotated maxillary left central incisor, there was even a greater risk. Therefore, the decision was made to place a fixed retainer consisting of a braided stainless steel (0.0175 in) wire from canine to canine to minimize the risk of relapse. In the mandibular arch, it was necessary to extract the first premolars to relieve the severe crowding in the incisor region and to flatten the occlusal plane. In addition, because the decision was made to close the space in the maxillary labial segment, extraction in the mandibular arch was indicated to maintain the Class I buccal segment relationship. During treatment, both the SNA and SNB values were reduced by 1°; the ANB value remained unchanged. When the Eastman correction was applied, the corrected ANB value was 5°. The maxillary and mandibular plane angles and the lower anterior face height increased slightly during treatment (Fig 8). This reflected the small amount of vertical growth as seen on the superimposition on the anterior cranial base. Toward the end of treatment, the mandibular incisors had proclined by 10° to 90°. The maxillary left central incisor was retroclined by 5° as a result of the overjet reduction. The interincisal angle was also reduced to an average value of 130° (Fig 9). The reduction in the interincisal angle and the normal edge centroid relationship should help to maintain the overbite reduction.10Houston W.J.B. Incisor edge-centroid relationships and overbite depth.Eur J Orthod. 1989; 11: 139-143PubMed Google ScholarFig 9Predebond cephalometric analysis.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The overall superimposition demonstrated that growth had occurred, which was in a downward and forward direction (Fig 10). The maxillary superimposition registered on the anterior surface of the zygomatic process of the maxilla showed a downward and slightly forward direction of movement. The maxillary incisors were extruded slightly from the Class ІІ intermaxillary traction, and the roots were torqued palatally. The maxillary molars were extruded slightly and remained relatively unchanged in the anteroposterior direction. Because a preadjusted fixed appliance with an MBT prescription was used, it allowed the opportunity to apply subtle tooth movements to improve the esthetics. The maxillary canine brackets were inverted to give a positive canine torque to reduce the canine eminence. This was supplemented with additional palatal root torque in the maxillary archwire. Moreover, the maxillary first premolars were rotated mesially, and buccal root torque applied to prevent any nonworking-side interferences on excursive movements of the mandible. The patient was extremely happy with the outcome, and the appliances were removed. The maxillary fixed retainer was bonded, and the patient was provided with maxillary and mandibular Essix retainers from the first molar to the first molar to wear during the night. There are claims in the literature that Essix retainers are more effective in maintaining the labial segments and are cost-effective, and patients preferred them over Hawley retainers.11Rowland H. Hichens L. Williams A. Hills D. Killingback N. Ewings P. et al.The effectiveness of Hawley and vacuum-formed retainers: a single-center randomized controlled trial.Am J Orthod Dentofacial Orthop. 2007; 132: 730-737Abstract Full Text Full Text PDF PubMed Scopus (116) Google Scholar, 12Hichens L. Rowland H. Williams A. Hollinghurst E. Ewings P. Clark S. et al.Cost-effectiveness and patient satisfaction: Hawley and vacuum-formed retainers.Eur J Orthod. 2007; 29: 372-378Crossref PubMed Scopus (132) Google Scholar Arrangements have been made to review the patient regularly during the retention phase of treatment. Furthermore, she was referred to her general dental practitioner for regular checkup appointments. An adolescent girl came with a Class I malocclusion complicated by developmentally absent maxillary lateral incisors and severe crowding in the mandibular labial segment. The treatment involved the use of preadjusted fixed appliances, extraction of the mandibular right and left first premolars, closing of the maxillary labial segment space, and canine substitutions for the maxillary lateral incisors.