ABSTRACT
Objective To evaluate the reliability of the panoramic radiographs for diagnosing mandibular asymmetry.Methods A total of 25 cases with no asymmetry in chief complaint or in appearance were selected for symmetry group.Pa and PAC from 16 cases of facial asymmetry were selected for asymmetric group.Marker points were fixed,a reference line and the reference plane drawn,and then relevant measurement items determined.The repeatability of the fixed position was observed.The difference of all measurement items between the left and right on Pa in symmetry group and asymmetric group were compared respectively and the asymmetric rate of corresponding measuredvalues on two sides between two groups were observed too.Correlation test was used to evaluate the measured-values on Pa and PAC in asymmetric group.Results Dispersion became smaller with the help of reference line and reference plane.And the dispersion was larger when Me was used as a marker other than MF.Most measured-values in symmetry group on Pa and all measured-values in asymmetric group on Pa showed statistically significant difference (P＜ 0.05).The mean difference of CP-GoP distance representing the vertical measured-value was 4.73 mm (P＜0.01); and the mean difference of GoP-MF distance representing the horizontal measured-value was 5.77 mm (P＜0.01).The horizontal measurements on PA and PAC showed closer correlation (r=0.78～0.85,P＜0.01) while the vertical was poorer (r=0.64,P＜0.01).Conclusions This study suggests that marking assisted with reference line and reference plane could get a more repeatable fixed-point on Pa.MF point could be used as a fixed-point for measuring mandibular asymmetry on Pa and the Pa measurement can be used to evaluate mandibular asymmetry.