Effects of orthodontic intermaxillary class III mechanics on craniofacial structures. Part II - computerized cephalometrics.

Abstract

The relation between active growth and induced anatomic changes was examined using a computerized cephalometric analysis of ten Class III cases treated with intermaxillary traction. The following can be concluded from this investigation: 1. Mandibular growth was redirected and mandibular opening was observed due to maxillary molar extrusion and counterclockwise rotation of the maxilla. 2. Condylar repositioning was noted to occur in all cases due to the effect of the external pterygoid muscle and a possible translatory movement during mandibular rotation. 3. Counterclockwise palatal development occurred in most of the treated cases through vertical action of the Class III mechanism. 4. The effect of the Class III traction was also observed in the mandibular incisor and molar teeth. The incisors retruded and the molars either were located in the predicted position or farther distally. 5. The soft tissue profile was less concave than the predicted value due to less mandibular growth and more retruded incisors in the treated cases. 6. Evidence was shown that a positive relationship exists between computerized cephalometrics and photoelastic techniques in the analysis of ten treated cases. This relationship is based on the fact that specific changes which took place during treatment were found to be consistent with the results of the photoelastic analysis.