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Adolescent Hypodontia: Management

Fig. 1a: Clinical view of malocclusion at initial presentation.
Clare McNamara, UK, Timothy Foley, Canada & Catherine M. McNamara, Ireland

Clare McNamara, UK, Timothy Foley, Canada & Catherine M. McNamara, Ireland

Thu. 19. February 2009

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Teamwork is essential in the management of hypodontia. Multidisciplinary consultation at the treatment planning stage and coordination and appropriate timing of subsequent inter-disciplinary dental care enables the clinician to provide optimum care. This is particularly critical in the management of hypodontia in adolescence, where a prolonged period of time is involved. This is illustrated in our case report of a 12-year-old Caucasian female. She required a combination of or­thodontic, oral surgery and restorative care to successfully treat her marked hypodontia.

Hypodontia is defined as the developmental absence of one or more teeth.1 The prevalence of hypodontia in the permanent dentition has been reported to range from 2.3% to 11.3%, depending on the population investigated.2–5

The aetiology of hypodontia is unknown,6 however a definite familial trend for hypodontia has been reported.7 Permanent first premolars, first molars and canines are very rarely developmentally absent. Their absence is usually associated with severe hypodontia or oligodontia.8

A meta-analysis by Polder9 on reported data between 1936 and 2002 found that the prevalence of hypodontia in Europe and Australia was higher than in North America. Hypodontia may occur in isolation or in association with syndromes such as ectodermal dysplasia, Down’s syndrome, Ellis van Crevald syndrome and con­ditions such as cleft lip and palate.5,10–13

Hypodontia presents a range of challenges for a clinician.5 A variety of treatment options are available. However, the most appropriate option will depend upon the severity of the case.

Simple restorative adhesive bridges may resolve the needs of mild hypodontia cases. Orthodontic treatment may provide the solution by moving adjacent teeth and closing the spaces. In more severe cases, a combined orthodontic/restor­ative/surgical approach may be necessary with orthodontic treatment needed to relocate space in preparation for later conventional fixed prostheses or implants.2,14–16

This case report of an adolescent Caucasian female who presented with significant hypodontia illustrates the importance of an accurate diagnosis and an effective treatment plan. These relied on appropriate coordination and timing of intervention between the dental specialists, orthodontist, oral surgeon and prosthodontist to achieve a successful outcome.

The timing of extraction of retained primary teeth is also significant to treatment outcome. This case report illustrates that sometimes it is better to delay the removal of retained primary teeth in order to maintain the surrounding dentoal­veolar bone until implants are feasible.

Case Report

A Caucasian female, aged 12 years 9 months, was referred by her family dentist for orthodontic care to the Graduate Orthodontic Clinic, University of Western Ontario. Her general medical history was not signif­icant. No family history of any oral or dental anomalies was found. Her past dental history was not significant. She was a regular dental attendee. She had no history of dental extractions.

Extra-oral examination revealed a well-balanced face with normal facial profile and normal skeletal dental base relationships. Intra-oral examination revealed a Class I malocclusion in the late mixed dentition (Figs. 1a–c).

A 2 mm maxillary median diastema was present and the maxillary left lateral incisor, 22, was microdontic. Oral hygiene and gingival status were good and no caries was found.

Radiographic examination confirmed that twelve teeth were developmentally missing: 18, 17, 12, 25, 27, 28, 31, 35, 38, 41, 45 and 48. Significant external root resorption was found in the retained primary teeth, 75 and 85 (Fig. 1b).

Given the patient’s presenting malocclusion, a multidisciplinary team approach involving orthodontics, oral surgery and advanced restorative dentistry was essential to the consultation process, treatment planning and later clinical management of this case.

The various treatment options open to the patient were considered. Selective extractions of the retained primary teeth, or their retention with build-ups, were inappropriate options given the severity of the hypodontia and the poor outcome that would arise. Also, the root form of two of the three retained primary molars was poor, rendering their long-term retention uncertain.

Limiting treatment to just one dental speciality such as orthodontics was unrealistic. Orthodontics alone could not close the spaces or deal appropriately with the anterior occlusal asymmetry arising from the absent.12

Therefore, in consultation with the patient a combined orthodontic/restorative/surgical team approach to care was undertaken. The objectives of orthodontic treatment were to correct the malocclusion and align the teeth in preparation for later prosthodontic care.

To assist the multidiscip­linary consultation process, a diagnostic set-up was carried out and an agreed treatment plan was achieved involving all three specialties (Figs. 2a & b). The orthodontic treatment embarked upon was a non-extraction approach using a pre-adjusted fixed appliance system (Fig. 3a).

Treatment commenced with the patient aged 13 years and 1 month. The patient was reviewed regarding her prosthodontic/restorative needs during orthodontic treatment and prior to debond (Figs. 3a–c). Debond was completed when the patient was 15 years and 5 months (Fig. 4a).

Due to the poor esthetics of 71 anf 81, both were extracted following debond (Fig. 4b). Conventional orthodontic retainers, with replacement dental units were fitted initially, with a view to the long-term insertion of implants and placement of final supra-structure fixtures (Fig. 5). The orthodontic goals during both the active and retentive phases were achieved.

The patient was followed in retention while awaiting maturation of her gingival unit and completion of her skeletal growth. Two years following debond the patient was assessed by the Fixed Prosthodontic and Oral Surgery Departments regarding the final management of the edentulous spaces.

At age 19 years, three implants were placed in the 12, 45 and the mandibular midline area. Due to the lack of dentoalveolar bone in the mandib­ular midline area, an augmentation bone graft harvested from the right external oblique ridge was necessary and was carried out six months prior to implant insertion. No sur­gical complications arose. Sub­sequently, coronal fixtures were placed in 12, 31, 41 and 45 (Figs. 6a & b).

The microdontic 22 was built up to ensure symmetry with 12 (Fig. 6a). For now, the mandibular left primary second molar, which has good function, is being retained. Long-term it is planned to replace this tooth with an implant. The patient, now aged 23 years, continues to be reviewed on an annual basis.

Discussion

This case report illustrates the necessity for a multidisci­plinary team approach to care of hypodontia, not alone at the treatment planning stage but throughout the entire course of treatment. The main objectives in the management of any hypodontia case are to improve esthetics and restore masticatory function, both of which were achieved for this patient.

Given that the patient presented in early adolescence, the timing of treatment and the coordination of care were ad­ditional critical components. Orthodontic treatment involved significant time, 2 years and 4 months, while implants and final prosthodontic restorations needed to be delayed until gingival maturation and skel­etal development were complete.

Good coordination was achieved between all three dental specialties from the beginning and through to the patient reaching adulthood. In cooperation with the patient, a combined agreed treatment plan was embarked upon and the patient was reviewed at planned intervals both during active orthodontic treatment and later during retention.

All the pre-treatment or­thodontic goals were achieved and without complication. Both arches were correctly aligned and coordinated. Normal buccal and incisor relationships were restored. The result was both occlusally and periodontally stable, while providing appropriate access for later implant insertion. Restorative and oral surgery care was timed appropriately and both specialities were delivered without complication.

One complication arose in the management of this case. Bone levels in the mandibular midline area pretreatment were low (Fig. 1b). Further bone loss occurred following the extraction of the primary central incisors and prior to implant insertion, resulting in the definitive need for dentoalveolar bone augmentation.

The coordination of the two mandibular primary central incisor extractions nearer to the time of implant insertion may have been the better option. However, for patient esthetics, these teeth were removed and esthetic replacements placed on retainers.

Conclusions

Marked hypodontia demands coordinated treatment planning and appropriate timing of delivery of care between dental specialities. Management of hypodontia in adolescent patients, where skeletal growth and gingival maturation are not yet complete, augments the need for good teamwork between dental specialities and over a prolonged period of time. This case report illustrated the principles in case management.

The following guidelines are suggested:

• Multidisciplinary referral/or consultation is important in treatment planning.
• Treatment planning for space management is best achieved prior to initiating orthodontic treatment.
• A diagnostic set-up is an essential adjunct to the treatment planning process.
• Tooth size measurements provide valuable data for evaluating the final tooth position and morphology.
• Careful consideration should be given to the timing of extraction of primary teeth and, if possible, coincide their removal with the time of implant insertion.

Editorial note: The original version of this article was published in the Journal of the Canadian Dental Association in Oc­tober 2006: http://www.cda-adc.ca/jcda/vol-72/issue-8/740.pdf.

Contact info

Clare McNamara
Department of Child Dental Health
Bristol Dental Hospital
University of Bristol
Lower Maudlin Street
Bristol, BS1 2LY
UK

Tel./Fax: +44 353 61 315 113
E-mail: tgmcnamara@eircom.net

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