Vertical lip height and dental height changes in relation to the reduction of overjet and overbite in Class II, Division 1 malocclusion.

Changes in vertical lip height in relation to dental height, overjet, and overbite of orthodontically treated Class II, Division 1 malocclusions are evaluated through cephalometric roentgenograms of twenty-two male patients. Treatment entailed extraction of the four first premolars and use of the edgewise technique. The results are statistically analyzed, and correlations between various binary combinations are subjected to the 1 percent confidence limit. On the basis of this study, it is concluded that (1) the reduction of overjet, overbite, and dental height with orthodontic treatment is statistically significant at the 1 percent level; (2) the reduction of overjet to that of overbite shows a mean ratio of 1.83 to 1. On the other hand, a reduction of 1 mm, in dental height is accompanied by an average reduction of 3.98 mm. in overjet and of 2.17 mm. in overbite; (3) there is also an insignificant increase in vertical lip height accompanied by a decrease in dental height. The relation is statistically insignificant, however.