Stabilisation of sagittal split advancement osteotomies with miniplates: a prospective, multicentre study with two-year follow-up. Part III--condylar remodelling and resorption.

This prospective study implied a two-year follow-up in a group of patients that underwent a Bilateral Sagittal Split Osteotomy (BSSO) for advancement of the mandible that were treated in seven institutions following the same treatment protocol (using two miniplates). The aim of Part III of this study was to define a Condylar Morphology Scale (CMS) and to analyse radiological changes in the TMJ after BSSO in relation to postoperative relapse and to determine the incidence of morphologic changes and its risk factors. It was concluded that the used 3-point CMS served its purpose well. In eight patients (4%) resorption of the condyle developed postoperatively. The value of preoperative cephalograms to predict condylar alterations appeared to be limited (12% explained variance). Patients treated at a relative low age (< or = 14 years) appeared to be at risk for the occurrence of condylar alterations including resorption. A steep mandibular plane angle and the low facial height ratio (post:ant) were also significantly related to the occurrence of condylar alteration, but the multi variance regression showed that these parameters had only limited value. The occurrence of pain and TMJ sounds in the first few months postoperatively are highly suspicious for condylar changes to occur in the next months.