Lower incisor angulation differences in Class II Division 1 malocclusions with and without full ‘lip trap’

A cephalometric study was designed to investigate whether a difference in lower incisor angulation exists in Class II division 1 malocclusion subjects with and without the presence of a Iower lip trap. Chinese subjects (N=40) with Class II division 1 malocclusions who demonstrated a complete lower lip trap were compared to an equal number of subjects with a partial lip trap. Intergroup comparisons of several cephalometric parameters indicated the presence of statistically significant differences in both the degree of lower incisor proclination/retroclination (p<0.01) and the magnitude of the overjet (p<0.05). In the complete lip trap group, the )ower incisor was more retroclined and the overjets were also statistically larger than the partial lip trap group.