Stability of changes associated with chin cup treatment.

Twenty-four Japanese girls with anterior crossbite (Class III malocclusion) were selected for this study of the stability of changes associated with chin cup therapy. Pretreatment cephalometric measurements of the study sample were compared with those in a normal group. In addition, angular and linear measurements were also compared to assess the effectiveness of chin cup therapy in improving Class III skeletal components during the postretention period. The subjects showed characteristic values found in Class III malocclusion for SNB, ANB, and NPg to FH, and these values were significantly different from those in the normal group. The subjects who were past puberty showed more severe Class III skeletal patterns for ANB compared with the prepubertal subjects, and their initial Class III skeletal components showed more satisfactory improvement, including 2.0 degrees increase of SNA and 1.8 degrees increase of ANB during the postretention period.