Preliminary Study Of Cephalometric Analyses On Effects Of Orthopedic Treatment On Mandibular Rotation And Condylar Growth In Angle Class Ⅱ Division 1 Malocclusions

Aim: This retrospective cephalometric study was to investigate the effects of orthopedic treatment on mandibular rotations and condylar gowth in ClassⅡ~1 malocclusions by Bjork structural superimposition method. And to get a better understanding of the relationship between mandibular rotations and condylar gowth as well as the mechanism of orthopedic treatment.Material and Method: 29 patients treated successfully with active orthopedic appliance (14 boys and 15 girls; mean age 10.8±1.3 at pretreatment) were selected and the lateral cephalograms were taken before and after the treatment. 17 untreated patients (8 boys and 9 girls; mean age 12.5±1.5 at preobservation) were included as the control. Cephalometric analyse were done based on superimposition of the films on the stable structure of the cranial base and mandible. rotation and intramatrix rotation) (—0.194±2.83°,—1.1±3.48°) and a backward trend of matrix rotation (0.91±3.04°) were exhibited in treated group, while a backward trend of mandibular rotations were showed in control. There was no statistically significant difference of mandibular rotation between the two groups.2. The treated group demonstrated a significantly upward and backward condylar growth direction(17.97+45.7°) and larger condylar growth amount (7.26±3.94mm) compared with the untreated group.3. There was a positive correlation between total rotation and the intramatrix rotation, In treated group, the intramatrix rotation still showed a negative relation to matrix rotation.4. There was a positive correlation between condylar growth direction and intramatrix rotation in both groups, while in treated group there still had a positive connection between total rotation and condylar growth direction. There were no relationship between condylar growth intensity and mandibular rotation in both groups.Conclusion:1. Orthopetic treatment had no significant effects on mandibular rotations, made condylar growth more upword and backward and intensity increased significantly.2. Mandibular intramatrix rotaion showed a positive correlation with total rotation, and a negative relation to matrix rotaion in treated group. 3. There was a positive correlation between condylar growth direction and two kinds of mandibular rotations(total rotation and intramatrix rotation ), and no correlation was found between condylar growth intensity and mandibular rotations.