Abstract

This study compared the cephalometric changes achieved using fixed versus removable appliances to correct deep overbite in growing patients. Forty-five patients treated with cervical headgear/tandem mechanics and 50 patients treated with a bionator appliance were compared with 95 control subjects from the Bolton Study. Treatment differences were determined using a cephalometric analysis that isolated vertical changes in overbite as the composite result of 6 variables: maxillary skeletal change, tipping of the upper incisors, bodily movement of the upper incisors, mandibular skeletal change, lower incisor tipping, and bodily movement of the lower incisors. The interaction of treatment type with facial type was also examined. In the headgear/tandem group, overbite was corrected by a combination of intrusion of the upper incisors and increases in mandibular skeletal change. Treatment with the bionator resulted in correction of the overbite by relative intrusion of the upper and lower incisors and increases in mandibular skeletal change. There were no significant interactions with facial type in the headgear group. Gonial angle and lower tipping were influenced by facial type in the bionator group. These results demonstrate that fixed and removable appliances produce both qualitative and quantitative differences in treatment response. Further studies are planned to create a rational decision tree that can be used to aid the clinician in the differential diagnosis and treatment of deep overbite.