OBJECTIVETo study the incisal jaw morphology of subjects with normal occlusion and to discuss the relationship between different vertical facial skeletal types and different incisal jaw cluster types.

METHODSAfter studied by radiographic cephalometry, the incisal jaw morphology of 169 subjects with normal occlusion in early permanent dentition were analyzed by K-mean cluster analysis.

RESULTSMorphology of maxillary or mandibular incisal jaws could be divided into four types separately, including division I, division II, division III and division N. In maxilla or in mandible, the incisal jaw morphology of division I was characterized by wideness and shortness. In contrast, division II was characterized by thinness and length. As for division III and division IV, both of two were intermediate types between division I and division II . In maxilla, it was found that division II was the majority (86.49%) in the high-angle subjects, division III was the majority (47.67%) in the average-angle subjects, and division I and III were the majority (82.61%) in the low-angle subjects. In mandible, it was found that division II was the majority (51.35%) in the high-angle subjects, division IV was the majority (48.84%) in the average-angle subjects, and division III and IV were the majority (69.57%) in the low-angle subjects.

CONCLUSIONOwing to the obvious characteristics of morphology in each cluster types and in each vertical facial skeletal types, different clinic considerations must be put forward when we want to move the incisor.