Cephalometric Analysis Of Skeletal Class Ⅲ Malocclusion With Different Vertical Types Among Adolescences

A cephalometic study was carried out to find the structural features of skeletal class â…¢ malocclusion with different vertical types among adolescences. In this study, 43 normal occlusions and 56 skeletal class â…¢ malocclusions, which were selected as samples, were taken cephalometric films . According to the growth pattern, the skeletal class â…¢ malocclusions were divided into three groups: average growth pattern(n=21), horizontal growth pattern(n=19) and vertical growth pattern(n=16). Cephalometric analysis and compare were performed with Enlow's counterpart analysis method and other characteristic indexes. The following result of statistical analysis can be showed from this investigation: 1. The Ba-S-N angle of the horizontal pattern group becomes smaller in skeletal class â…¢ malocclusion group than that in normal occlusion group(P<0.05). The difference of the Ba-SE-FMS angle is non-significant between normal occlusion group andskeletal class â…¢ malocclusion group(P>0.05). The lengths of So-Cd in both groups are equal(P>0.05). 2. The lengths of UA-FA, SE-X and So-Ra between the normal occlusion group and malocclusion group are non-significantly different(P>0.05). The proportions among three counterparts has abnormally showed in the skeletal horizontal malocclusion group (all P values <0.01). 3. Difference of the lower facial height between normal occlusion group and malocclusion group is non-significant (P>0.05). The upper facial height and the whole facial height in skeletal horizontal malocclusion group decrease significantly (P<0.01). However, the length of S-Go in skeletal vertical malocclusion group is shorter than that in normal occlusion group (P<0.05). In both horizontal and vertical skeletal malocclusion groups, the proportions of N-ANS/N-Me and ANS-Me/N-Me increase significantly (P<0.05). 4. In skeletal class â…¢ malocclusion, generally, the upper teeth incline forward, and the lower teeth incline backward. The alveolar heights of U1, U4 and U6 are non-significantly different (P>0.05). 5. The FOP-NOA and FOP-FH in skeletal horizontal malocclusion group decrease significantly (P<0.05). In both average and vertical skeletal malocclusion groups, the FOP-MP angle increases significantly (P<0.05 and P<0.01, respectively). This study revealed some conclusions that followed: 1. Change of the cranial basis of skeletal class â…¢ malocclusion is non-significant in vertical dimension. 2. Lengths of UA-FA,SE-X and So-Ra between the normal occlusion group and malocclusion group are similar. 3. The upper alveolar heights are non-significantly different , and the lower alveolar height decreases significantly. 4. In both horizontal and vertical skeletal malocclusion groups, the lower facial height increases against the upper facial height. 5. The occlusion plane rotates counterclockwise and has a horizontal tendency in three vertical facial patterns of skeletal class III malocclusion.