The purpose of this study is to define the characteristics of the skeleton and soft tissues of severe adult class III malocclusion. The materials selected for this study were lateral cephalograms of 112 adult class III malocclusion patients with ANB difference below -2 degrees. and the mean age was 22.9 years old. The normal control samples consisted of lateral cephalograms of 50 adults in normal occlusion and the mean age was 22.1 years old. The Horizontal reference line was FH line and the vertical reference line was nasion perpendicular to FH line.
The skeletal and soft tissue characteristics of Class III malocclusion are as follows
1. In the skeletal profile evaluated by vertical reference line (Nasion perpendicular to FH), the forehead and maxilla was similar to normal, but the mandible was protruded significantly.
2. The soft tissue profile is concave. The thickness of soft tissue covering forehead area and nose is within normal
range. but the upper lip is thicker and the nasolabial angle is smaller than normal. The lower lip and inferior
labial sulcus is thinner than normal. The degree of eversion of lower lip is lesser than normal.
3.´ The cranial base of class III malocclusion is shorter and saddle angle is smaller than normal.
4. The location of midface evaluated in relations to cranial base is within normal range but, the length of midface
is shorter than normal when compared from the deep portion of the facial skeleton.
5. The location of maxilla in reference to cranial base is within normal range but the length of maxilla was shorter
in class III malocclusion.
6. The mandible was protruded, ramus height and body length, gonial angle were greater than normal, and the chin angle was smaller.
7. Upper, incisor was proclined, lower incisor was retroclined.
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