Analysis of mandibular position of patients with Angles Class I and ClassII,Di vision 1 malocclusion

Objective To study changes of condyle position and occlusion betw een centric jaw relation and maximum intercuspation positions. Methods The power centric registration advocated by Roth was used to take centric relation bite re gistration for 50 patients (25 Class I and 25 ClassⅡ,Division 1) and diagnosti c models were mounted and analysed with Panadent articulator and condyle positio n indicator. Results Nearly all patients had CR-MI difference s in all three planes of space. 70% of the sagittal displacement was within 2. 0 mm an d 87% of the transverse displacement was within 1.0 mm. Most of the condyles m ov ed posteriorly and inferiorly. 65% of the initial contacts in CR occured on the most posterior molar on single side. Correlation was found between some varia bles of condylar displacement and occlusion changes. No significant difference was observed in condylar position and occlusion changes between Class I and Clas sⅡ,Dvison 1 patients. Conclusions The occlusion in centric j aw relation should be analysed before treatment to reveal the disharmony between occlusion and jaw position.