Treatment of mandibular asymmetries during growth. A longitudinal study.

Abstract

The purpose of this work was to investigate whether some mandibular asymmetries are adaptive to mandibular displacement during growth and can consequently be treated by orthopaedic means. Eleven growing subjects with mandibular asymmetry and a lateral chin deviation were selected: they all showed a malocclusion consistent with an ipsilateral mandibular displacement at an earlier age. Posteroanterior and lateral cephalometric radiographs and TMJ oblique lateral transcranial radiographs (TRs) were taken in intercuspal position. On the posteroanterior radiographs 7 points were selected to define three areas (mandibular, upper cranial and craniomandibular) bilaterally. The position of the highest condylar point inside the glenoid fossa was also digitized and assessed. A ‘position of symmetry’ was determined on the posteroanterior radiographs and repositioning splints were constructed to permanently hold the mandible of the subjects in this position. Orthodontic treatment followed so that the intercuspal position would finally coincide with the position of symmetry. Radiographic data were collected and processed again after splint insertion and at the end of a mean observation period of 37.6 months (s.d. 8.89). Further radiographs were taken at intervals of 6–12 months. After the observation period a consistent improvement in mandibular symmetry had occurred in 9 out of 11 patients. This was due to compensatory mandibular and condylar growth on the side where these had been hampered as a consequence of mandibular displacement.