A study on the effect of the chincap by finite element analysis in juvenile skeletal Class III patients

Choi, Jeong Ho; Yang, Won Sik

Abstract

This study was conducted to investigate the changes in the structural parts of the craniofacial skeleton subsequent to chincap therapy in the juvenile skeletal Class Ill Patients. The subject consisted of 29 Korean children(14 males, 15 females) who had skeletal Class M malocclusion and were undergone chincap therapy from the beginning of the treatment (and an auxiThary upper removable appliance, if necessary). The control group was composed of 21 children(10 males, 11 females) with skeletal Class Ill malocclusion who had no orthodontic treatment. Cephalometric data at the mean age of 7 and 2 years later were analyized by finite element method, and compared between groups by independent group t-test(p<0.05). The results of the present study were as follows; 1. There were no significant changes in the cranial base, posterior face, upper anterior face, ramus, chin and soft tissues by the chincap therapy. 2. The mandibular body showed significant differences in the minimum extention ratio and the overall shape ratio. This means that the vertical direction of growth was retarded by the chincap therapy. 3. The major direction of the growth in the maxillary basal bone was significantly more horizontal in the experimental group, which suggests that the vertical growth of maxilla was inhibited. 4. There was statistical difference in the major direction of the growth of the anterior face between groups. This may be due to the significant difference in the major direction of growth of the lower anterior face, supposed to be resulted from the mandibular rotation and/or displacement by the chincap therapy. The change in the oral functional space seemed to be caused by the same reason. 5. From the standpoint of these results, the retardation of growth, the changes of the growth direction and the morphological changes could be accepted partly, but the major effect of the chincap seems to be the rotation and the displacement of the mandible.