Objective: To study craniofacial structures of Uygur adults with normal occlusion and establish the standard cephalometric values to evaluate the craniofacial soft and hard tissue structures of normal Uygur adults.
Methods: Lateral cephalometric radiographs of 93 Uygur adults with normal occlusion (43 men and 50 women) were evaluated with the same standard. Their age ranged from 18 to 25 years old, and they had normal and well-balanced faces without receiving any orthodontical treatment. The lateral cephalogram of each normal adult was traced digitized and measured by the same computer system, then the indexes of craniofacial structures were analyzed by multifactor cluster analysis. 18 typical items were chosen to analyze the characters of the craniofacial structures of Uygur adults with normal occlusion. At the same time, Bayers discriminant analysis was used to identify and evaluate the cluster results.
Results: Uygur adults with normal occlusion were divided into three patterns according to the multifactor cluster analytic results: horizontal tendency pattern (40%), medial pattern (43%) and vertical tendency pattern (17%). When the horizontal tendency pattern was compared with the medial pattern, it showed that the height of S-Go increased (P < 0.05), while the height of ANS-Xi-Pm decreased (P < 0.05); The proportion of S-Go/N-Me increased (P < 0.01). The angle of Ar-Go-Me and Y axis decreased (P < 0.05), which meant that the mandible rotated in the counter-clockwise direction. SN-MP, PP-MP, OP-MP, MP-FH all decreased (P < 0.01), which meant that the SN plane, the PP plane, the occlusion plane and the MP plane all had the trend of hypodivergence. When the vertical tendency pattern was compared with the medial pattern, the height of Ar-Fo decreased (P < 0.01), while the height of ANS-Me increased (P < 0.01); The angle of Ar-Go-Me, Y axis, SN-MP, PP-MP, OP-MP and MP-FH all increased (P < 0.01). These results showed that the mandible rotated in the clockwise direction and the SN plane, the PP plane, the occlusion plane, and the MP plane all had the trend of hyperdivergence. At last, according to the different skeletal patterns, the normal cephalometric values of Uygur adults with normal occlusion were established.
Conclusion: Significantly craniofacial structure difference exist in the adults with normal occlusion. Therefore, it is necessary to establish the normal cephalometric values of Uygur adults with normal occlusion according to different skeletal patterns.