[Hypodontia: therapeutic strategy elaborated from 30 cases]

Hypodontia is defined as the absence of at least six permanent teeth due to the hypodevelopment of tooth germs. The prevalence is weak and varies according to the ethnic origin. This familial abnormality is due to various mutations or polymorphisms of genes. It may be associated with other dental abnormalities. In children, it is responsible for growth, mastication, and phonation disorders, hypo-alveolia and lingual interposition in the toothless sites. We report the management of 30 patients presenting with oligodontia.

The diagnosis was made on clinical and paraclinical data. The vertical and transversal facial dimensions, the three facial proportions, labial morphology, the number and localization of teeth, and occlusion were analyzed for future orthognathic and implant rehabilitation. The occlusion was studied transversally and vertically on dental casts. Rehabilitation with implant supported dental prostheses was chosen when conditions were met. The therapeutic protocol could include up to four chronological phases: the early prosthetic phase, the orthodontic phase, the surgical phase, and the implant and prosthetic phase.

The 30 patients' age (13 male and 17 female patients) ranged from six to 20 years. An average of 15 dents were missing (6 to 28). Except for one case, all the third molars were missing. In 66% of the cases, the second molar was missing, in 33% for the first molar. In 66% of the cases, two lateral maxillary incisors were missing. There were no premolars in 50% of the patients. Agenesis of premolars and molars induced posterior bone insufficiency in the mandibula. Dysmorphosis was always present with vertical growth disorders. Six patients were not given orthodontic treatment because they did not have enough teeth. Orthognathic surgery was used in 14 cases (46.7%). Seventeen patients (56.7%) underwent apposition graft. In three patients, a high position of the alveolar nerve required nerve derivation. Implants were inserted in 14 patients (46.7%). The total number of implants was 155.

Rehabilitation with implant supported dental prostheses is a good treatment for oligodontia. It requires an interdisciplinary approach (including a maxillo-facial surgeon, an orthodontist, a dentist, and a prosthesis specialist). The patient's motivation as well as that of his family is crucial.