“Effective” TMJ and Chin Position Changes in Class II Treatment

Abstract

To evaluate the "effective" temporomandibular joint (TMJ) changes (the sum of condylar modeling, glenoid fossa modeling, and condylar position changes within the fossa), and their influence on chin position in patients with a Class II division 1 malocclusion treated orthodontically with a multibracket appliance and Class II elastics (Tip-Edge) and orthopedically with a fixed functional appliance (Herbst). Two groups of successfully treated subjects were evaluated: Tip-Edge (n = 24) and Herbst (n = 40). The Bolton Standards served as a control group. Lateral head films obtained before treatment and after an observation period of 2.6 years (Herbst also after 0.6-year period) were analyzed. In comparison with the Herbst and control groups, the Tip-Edge group exhibited less favorable sagittal "effective" TMJ growth and chin position changes necessary for skeletal Class II correction. Orthodontic therapy with a multibracket appliance and Class II elastics seems not to have any favorable sagittal orthopedic effect on the mandible, while bite jumping with the Herbst appliance has a favorable sagittal orthopedic effect on a short-time basis.