Objectives:The purpose of this study was to get standard data for the 3D analysis of asymmetry and obtain mean values of 3D-CT image measurements of mandible and the normal range of the asymmetry of right and left side from normal occlusion individuals.
Methods:CT of the 60 normal occlusion individuals who didn't have any apparent asymmetry were taken. The CT-images were transmitted to personal computers and then reconstructed into 3D-CT by using V-worksTM(Cybermed Inc., Seoul, Korea). Through the computer processing, a total of 23 liner and angular measurements were obtained. Next, a mean value and a standard deviation of each measurement were carried out according to male and female. Last, the difference value of the left and right side and difference from the comparison of male to female were analyzed.
Results:1. The comparison of each measurement between right and left sides didn't show the statistically significant difference from all measurements.
2. The results from the comparison of linear measurements of male to those of female showed that measurements of male were greater than those of female at all the linear measurements.
3. The result from the comparison of the angular measurements of male to those of female which represent the shape of mandible showed that there were a little differences at a lateral ramal inclination, but female's measurements were greater than those of male at gonial angle and frontal ramal inclination.
4. The right and left difference values which could be used as standard measurements of asymmetric diagnosis showed a little numerical values that were approximately 1.0-3.0mm at linear measurements and 1.0-3.0¢ªat angular measurements.
Conclusions:These results suggest that the right and left difference of measurements obtained from normal occlusion individuals using by 3D images of mandible could be used as references for an orthodontic diagnosis and a treatment planning for asymmetry.