Methods: 3D CT from mandibular prognathism and retrognathism paitents and normal control volunteers was used. We reconstructed 3D image and measured the length and angles of mandibular structure according to the facial growth and development. Then we compared the structural characteristics of mandible between the types of the deformity.
Results: Class III group was the one with the longest condyle length and class II the shortest. Coronoid lengths of three groups were similar. But the angular length showed the different that class I was relatively longer than class II and III. The relative length of condyle to coronoid in class I , II, and III group was 1:1.08, 1:0.92 and 1:1.16 respectively. And the angulation of condylar head and condyle-coronoid angle in class III group was smaller than other groups and class II the largest. It can suggest the angulation of condyle and coronoid is differently modified in each DFD group. But condylar axis with FH plane was almost the same, which means the direction of condylar growth may not be affected by the type of deformity.
Conclusion: We confirmed some meaningful mandibular landmarks, lengths, and angles, which are thought to be related with the mandibular development and growth by 3D CT and compared them in DFD patients with normal controls.