[Application of cephalometric study of the rest position to diagnosis of reversed occlusion cases]

A cephalometric study of reversed occlusion in the rest position was performed. Materials consisted of cephalograms which were taken from 20 Japanese with reversed occlusion Study was made of the 2 dimensional changes in cephalograms before and after treatment, in order to determine its value for the estimation of the mandibular position after treatment of reversed occlusion, for therapeutic purposes, and also its value as a rotational element in preparation of Ricketts' V.T.O. Superimposed cephalometric tracings were made in the pretreatment and posttreatment rest positions. Using these, the method was evaluated for current use in analysis. The superimposition of tracings enabled estimation of the mandibular position and habitual position with an accuracy of 80% (16/20 cases). Coincidence of posttreatment mandibular position and pretreatment rest position was obtained in all adult cases. Utilization of the rest position for preparation of Ricketts' V.T.O. made it possible to estimate the growth direction and the mandibular position with an accuracy of 65%. Superimposition of pretreatment rest position and posttreatment habitual occlusal position led to coincidence of V.T.O. 84% of the time. Case analysis by means of Rákosi's functional analysis was effective for the determination of the relative therapeutic difficulty and the therapeutic approach. Utilization of the rest position, in addition to Kim's ODI and APDI values proved to be capable of determining the exact therapeutic plan at a probability of 70%. The above results revealed that the preoperative rest position was effective, not only for functional analysis, but also for the estimation of the therapeutic goal for adult cases and of the first stages-completion (at the overjet correction) for young cases.