Orthodontic Treatment for a Patient with Hypodontia Involving the Maxillary Lateral Incisors

CASE REPORT

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

Saud A. Al-Anezi Kuwait City, Kuwait

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. (Am J Orthod Dentofacial Orthop 2011;139:690-7)

ypodontia is the developmental absence of at factors include skeletal pattern, type of malocclusion, Hleast 1 tooth.1 The incidence of missing maxil- number of missing teeth, size, shape, and the gingival lary lateral incisors is 1% to 2% in white popula- margin of the maxillary canines. In this case report, an tions.2 The etiology of hypodontia can be genetically adolescent girl complained of the appearance of her determined and arises as a familial condition. The condi- maxillary anterior teeth because of developmentally ab- tion is more common bilaterally than unilaterally and sent lateral incisors and crowding in the mandibular arch. can be associated with impacted maxillary canines. This condition causes several problems, including un- DIAGNOSIS AND ETIOLOGY sightly spacing between the anterior teeth, and drifting This girl, aged 14.6 years, had an Angle Class _ mal- and rotation of the central incisors and the canines. In occlusion on a mild Class __ skeletal pattern with reduced unilateral cases, these effects are asymmetric and can re- Frankfort mandibular plane angle and lower anterior sult in a midline shift. Furthermore, dental health prob- face height. There was no facial asymmetry, and the lems might arise because of food impaction as a result of lips were competent with a low smile line (Fig 1). In tipped teeth. A suspected absence of the maxillary per- the intraoral assessment, her oral hygiene was fair but manent lateral incisor should be confirmed radiograph- needed improvement before orthodontic treatment. ically if the tooth has failed to erupt by the age of 9 years, The erupted teeth were as follows. or within 6 months of the contralateral tooth.3 The management of missing maxillary lateral incisors 65431 13456 often needs a multidisciplinary approach and can be 7654321 1234567 broadly divided into space closure, space opening, and Both maxillary and mandibular left first molars were space redistribution. A number of factors should be hypoplastic but not carious. Fissure sealants were pres- considered in the management of such patients.4 These ent occlusally in all first molars. From the history and include patient factors: age, medical history, motivation, clinical examination, these teeth did not cause any prob- and attitude toward orthodontic treatment. Other lem to the patient (eg, sensitivity), and the long-term prognosis was good. The maxillary arch had spacing, Specialist orthodontist, Orthodontics Department, Bneid Al-Gar Specialty Dental Center, Ministry of Health, Kuwait. whereas the mandibular arch was severely crowded. The authors report no commercial, proprietary, or financial interest in the prod- Overjet was 5.5 mm, and overbite was deep with palatal ucts or companies described in this article. impingement. The molar relationship was Class I on both Reprint requests to : Saud A. Al-Anezi, Orthodontics Department, Bneid Al-Gar Specialty Dental Center, Ministry of Health, PO Box 11610, Dasma 35156, sides, and the incisor relationship was Class II Division 2 Kuwait; e-mail, [email protected]. (Fig 2). The maxillary canines were in crossbite. Further- Submitted, June 2009; revised, September 2009; accepted, October 2009. more, the maxillary left central incisor and the maxillary 0889-5406/$36.00 Copyright Ó 2011 by the American Association of Orthodontists. right second premolar were rotated; these might cause doi:10.1016/j.ajodo.2009.10.042 some concern in terms of stability and risk of relapse.

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Fig 1. Pretreatment clinical photographs.

The mandibular left second premolar was partially erup- and the mandibular incisor to the APo line was within ted. In addition, space analysis showed that the space normal limits. The lower lip was positioned posteriorly requirement in the mandibular arch was 14 mm. to the E-line. The dental panoramic tomogram conﬁrmed the pres- The malocclusion was complicated by the develop- ence of all permanent teeth except the maxillary lateral mentally absent maxillary lateral incisors, increased incisors and the third molars. Teeth yet to erupt were and complete overbite, severe crowding in the mandib- the maxillary and mandibular second molars and the ular arch and the crossbite involving the maxillary ca- mandibular third molars (Fig 3). Root length and mor- nines. The genetically inherited skeletal pattern and phology appeared normal. In the cephalometric assess- the reduced vertical proportions contributed to the mal- ment (Fig 4 and Table). The ANB value was 3, which occlusion. In addition, the high lower lip line contributed suggested a Class _ skeletal pattern. However, by apply- to the retroclination of the maxillary right central incisor. ing the Eastman correction (SN/Max 10), the corrected ANB was 5, which indicated a mild Class __ skeletal pat- TREATMENT OBJECTIVES tern.5 The mandibular incisor inclination was retroclined The treatment objectives included (1) accept the pa- at 80. The maxillary left central incisor was proclined at tient’s proﬁle, (2) relieve the crowding in the mandibular 118, and the maxillary right central incisor appeared labial segment, (3) level and align, (4) reduce the over- retroclined. The lower anterior face height was reduced, bite, (5) reduce the overjet and correct the crossbite

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Fig 2. Pretreatment models. involving the maxillary canines, (6) close the maxillary severity of the mandibular arch crowding necessitated spacing, (7) substitute the maxillary canines as lateral the extraction of the mandibular premolars. As a conse- incisors, and (8) retain. quence, there was a need to compensate for the extrac- The decision to close the space in the maxillary labial tions in the mandibular arch with extractions in the segment was based on the fact that the patient had maxillary arch, because the malocclusion was essentially a mild Class __ skeletal pattern with a slightly increased Class I. Because the maxillary lateral incisors were devel- overjet. In addition, the shape and the color of the max- opmentally absent, further extractions in the maxillary illary canines were considered favorable in terms of es- arch were not required. In addition, the color and mor- thetics. Restorative treatment was planned to reshape phology of the maxillary canines were encouraging to the maxillary canines and camouflage their appearance. use them as lateral incisors. The severity of crowding in the mandibular labial segment indicated the necessity to extract the mandibular TREATMENT PROGRESS fi left and right rst premolars. The patient was treated The treatment progressed well without major compli- with a fixed appliance with a 0.022-in slot McLaughlin, 6 cations. The patient was cooperative, and her oral hy- Bennett, Trevisi (MBT) prescription. The maxillary giene improved as the treatment progressed. Overbite fi xed retainer was chosen to minimize the risk of relapse reduction started slowly at the beginning of treatment of the severely rotated maxillary left central incisor. In (Fig 5). The banding of the mandibular second molars addition, the patient was provided with maxillary and helped in controlling the overbite. The use of Class __ in- mandibular Essix retainers (DENTSPLY Limited, Surrey, termaxillary traction helped to reduce the overjet and fi fi United Kingdom). from the rst molar to the rst molar close the maxillary space. This also had the effect of ex- to wear at night only. truding the mandibular molars and ultimately helped with the overbite reduction. A reverse curve of Spee TREATMENT ALTERNATIVES was placed in the mandibular archwire to further reduce As an alternative, space opening in the maxillary arch the overbite.7 This was necessary before the space clo- and replacement of the maxillary lateral incisors with im- sure phase of treatment. During treatment, space closure plants might have been considered. However, the in the mandibular arch progressed well. However, space

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Fig 4. Pretreatment cephalometric tracing.

DISCUSSION 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 in- Fig 3. Pretreatment dental panoramic tomograph and lat- crease in the overjet; therefore, space closure would eral cephalometirc radiograph. also lead to a reduction in the overjet. The smile line was low, so that the discrepancies in the gingival mar- gins of the canines and the central incisors would not closure in the mandibular right quadrant was slow. Ra- be apparent. Another important advantage of space clo- diographic assessment showed that the roots of the sure was that the gingival tissue and interdental papillae mandibular right canine and the second premolar were would change in synchrony with the patient’s own teeth too close together. This was rectified with bracket repo- over her lifetime.8 sitioning and artistic bends in the archwire as the space However, there are potential disadvantages with the was closed. space-closure approach. Moving the canine mesially next to the central incisor might not be esthetically TREATMENT RESULTS pleasing, since the cusps are prominent and these teeth The duration of active treatment was 23 months, and are naturally darker than the lateral incisor. In this pa- the treatment objectives were achieved. The patient’s tient, the morphology and the color of the maxillary ca- profile was maintained (Fig 6). At the end of treatment, nines were encouraging. A restorative camouflage the maxillary labial segment space was closed by move- consisting of careful grinding, composite buildup, and ment of the canines mesially. The incisor relationship bleaching was an integral part of the treatment plan. was Class I. The overjet at the end of treatment was 2 Nonetheless, the patient was satisfied with the outcome mm. The mandibular crowding was relieved, and the of the grinding and reshaping of the canines without the mandibular incisors were aligned (Fig 7). The overbite need for composite buildup or bleaching. was dramatically reduced. The bilateral crossbites in- Another potential disadvantage is that placing the volving the mandibular canines were eliminated, and first premolar in the position previously occupied by the dental midlines were coincident. the canine might result in heavy occlusal forces, since

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Table. Cephalometric analysis

Variable Pretreatment Normal* Predebond Overall change SNA 86 82 6 3 85 À1 SNB 83 79 6 3 82 À1 ANB 3 3 6 1 3 0 Maxillary incisor to maxillary plane angle 118 108 6 5 113 À5 Mandibular incisor to mandibular plane angle 80 92 6 5 90 À10 Interincisal angle 142 133 6 10 130 À12 Maxillary-mandibular planes angle 20 27 6 5 23 3 Face height ratio 52% 55% 54% 2% Mandibular incisor to APo line À2mm 0–2 mm 1 mm 3 mm Lower lip to Ricketts’ E-plane À4mm À2mm À1mm 3mm SNA, 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.13

Fig 5. Progress intraoral photographs showing the maxillary and mandibular 0.020 3 .0.020-in nickel- titanium archwires.

canine-protected occlusion is not possible. The roots of In addition, because the decision was made to close the the first premolars are thinner and smaller; therefore, space in the maxillary labial segment, extraction in the there is a concern of potential damage to the periodontal mandibular arch was indicated to maintain the Class I health. However, a long-term study failed to demon- buccal segment relationship. strate this effect, and some studies are in favor of the During treatment, both the SNA and SNB values were space-closure option.9 reduced by 1; the ANB value remained unchanged. Finally, there is a risk of space reopening in any When the Eastman correction was applied, the corrected space-closure treatment. In this patient, because of the ANB value was 5. The maxillary and mandibular plane rotated maxillary left central incisor, there was even angles and the lower anterior face height increased a greater risk. Therefore, the decision was made to place slightly during treatment (Fig 8). This reflected the small a fixed retainer consisting of a braided stainless steel amount of vertical growth as seen on the superimposi- (0.0175 in) wire from canine to canine to minimize the tion on the anterior cranial base. Toward the end of risk of relapse. In the mandibular arch, it was necessary treatment, the mandibular incisors had proclined by to extract the first premolars to relieve the severe crowd- 10 to 90. The maxillary left central incisor was retro- ing in the incisor region and to flatten the occlusal plane. clined by 5 as a result of the overjet reduction. The

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Fig 6. Posttreatment clinical photographs. interincisal angle was also reduced to an average value The maxillary canine brackets were inverted to give of 130 (Fig 9). The reduction in the interincisal angle a positive canine torque to reduce the canine eminence. and the normal edge centroid relationship should help This was supplemented with additional palatal root tor- to maintain the overbite reduction.10 que in the maxillary archwire. Moreover, the maxillary The overall superimposition demonstrated that first premolars were rotated mesially, and buccal root growth had occurred, which was in a downward and for- torque applied to prevent any nonworking-side interfer- ward direction (Fig 10). The maxillary superimposition ences on excursive movements of the mandible. registered on the anterior surface of the zygomatic pro- The patient was extremely happy with the outcome, cess of the maxilla showed a downward and slightly for- and the appliances were removed. The maxillary fixed re- ward direction of movement. The maxillary incisors were tainer was bonded, and the patient was provided with extruded slightly from the Class __ intermaxillary trac- maxillary and mandibular Essix retainers from the first tion, and the roots were torqued palatally. The maxillary molar to the first molar to wear during the night. There molars were extruded slightly and remained relatively are claims in the literature that Essix retainers are more unchanged in the anteroposterior direction. effective in maintaining the labial segments and are Because a preadjusted fixed appliance with an MBT cost-effective, and patients preferred them over Hawley prescription was used, it allowed the opportunity to ap- retainers.11,12 Arrangements have been made to review ply subtle tooth movements to improve the esthetics. the patient regularly during the retention phase of

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Fig 7. Posttreatment models.

Fig 8. Predebond lateral cephalometric radiograph.

Fig 9. Predebond cephalometric analysis.

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segment space, and canine substitutions for the maxillary lateral incisors. I thank the patient, her family, and all the staff in the orthodontics department at the Royal United Hospital, Bath, United Kingdom.

REFERENCES 1. Goodman JR, Jones SP, Hobkirk JA, King PA. Hypodontia: clinical features and the management of mild to moderate hypodontia. Dent Update 1994;21:381–4. 2. Zilberman Y, Cohen B, Becker A. Familial trends in palatal canines, anomalous lateral incisors, and related phenomena. Eur J Orthod 1990;12:135-9. 3. Isaacson KG, Thom AR, Horner K, Whaites E. Orthodontic radiographs: guidelines. London, United Kingdom: British Orthodontic Society; 2008. 4. Carter NE, Gillgrass TJ, Hobson RS, Jepson N, Meechan JG, Nohl FS, et al. The interdisciplinary management of hypodontia: orthodontics. Br Dent J 2003;194:361-6. 5. Mills JR. The application and importance of cephalometry in orthodontic treatment. Orthodontist 1970;2:32-47. 6. Bennett JC, McLaughlin RP. Orthodontic management of the dentition with the preadjusted appliance. St Louis: Mosby; 2001. 7. Parker CD, Nanda RS, Currier GF. Skeletal and dental changes associated with the treatment of deep overbite malocclusion. Am J Orthod Dentofacial Orthop 1995;107:382-93. 8. Rosa M, Zachrisson BU. Integrating esthetic dentistry and space Fig 10. Overall superimposition of pretreatment (black) closure in patients missing maxillary lateral incisors. J Clin Orthod and predebond (red) cephalometric radiographs, regis- 2001;35:221-34. tered on the stable structures in the anterior cranial base. 9. Robertsson S, Mohlin B. The congenitally missing upper lateral incisor. A retrospective study of orthodontic space closure versus restorative treatment. Eur J Orthod 2000;22:697-710. treatment. Furthermore, she was referred to her general 10. Houston WJB. Incisor edge-centroid relationships and overbite dental practitioner for regular checkup appointments. depth. Eur J Orthod 1989;11:139-43. 11. Rowland H, Hichens L, Williams A, Hills D, Killingback N, Ewings P, CONCLUSIONS et al. The effectiveness of Hawley and vacuum-formed retainers: a single-center randomized controlled trial. Am J Orthod Dentofa- An adolescent girl came with a Class I malocclusion cial Orthop 2007;132:730-7. complicated by developmentally absent maxillary lateral 12. Hichens L, Rowland H, Williams A, Hollinghurst E, Ewings P, incisors and severe crowding in the mandibular labial Clark S, et al. Cost-effectiveness and patient satisfaction: Hawley and vacuum-formed retainers. Eur J Orthod 2007; segment. The treatment involved the use of preadjusted 29:372-8. ﬁxed appliances, extraction of the mandibular right and 13. Houston WJ, Stephens CD, Tulley WJ. A textbook of orthodontics. left ﬁrst premolars, closing of the maxillary labial Wright, Oxford: United Kingdom; 1992.

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