Adaptive condylar growth and mandibular remodelling changes with bionator therapy--an implant study.

The purpose of this study was to describe condylar growth and mandibular remodelling changes associated with bionator therapy. Twenty-five patients (15 males and 10 females) between 6.9 and 11.2 years of age with Class II division 1 malocclusions were randomly allocated to either control (n = 11) or treatment (n = 14; bionator only) groups and followed longitudinally for approximately 1 year. Treatment consisted of a bionator only, constructed to clear the buccal dentition by 2 mm and to position the mandible into an edge-to-edge incisor relationship. Using metallic implants for superimposition, mandibular growth, displacement, and true rotation were evaluated cephalometrically. The results showed significant changes in the direction (more posterior) but not in the overall amount of condylar growth. The bionator appliance produced greater than expected posterior drift of landmarks in the condylar and gonial regions. Cranial base superimposition showed greater than expected anterior mandibular displacement, but little or no true mandibular forward rotation with bionator therapy. The bionator appliance alone produced changes in condylar growth direction and remodelling changes associated with mandibular rotation and displacement.