Abstract:

Objective　To study the incisal jawmorphology of subjectswith normal occlusion and to discuss the relationship be- tween different vertical facial skeletal types and different incisal jaw cluster types.Methods　After studied by radiographic cephalometry, the incisal jawmorphology of 169 subjects with normal occlusion in early permanent dentition were analyzed by K- mean cluster analysis.Results　①Morphology of maxillary ormandibular incisal jaws could be divided into fourtypes separately, including divisionⅠ、divisionⅡ、divisionⅢand divisionⅣ. In maxilla or in mandible, the incisal jawmorphology of divisionⅠ was characterized by wideness and shortness. In contrast, divisionⅡwas characterized by thinness and length. As for divisionⅢ and divisionⅣ, both of twowere intermediate types between divisionⅠand divisionⅡ.②Inmaxilla, itwas found that divisionⅡ was the majority(86·49%)in the high-angle subjects, divisionⅢwas the majority(47·67%)in the average-angle subjects, and divisionⅠandⅢwere the majority(82·61%)in the low-angle subjects. Inmandible, itwas found that divisionⅡwas the major- ity(51·35%)in the high-angle subjects, divisionⅣwas the majority(48·84%)in the average-angle subjects, and divisionⅢand Ⅳwere the majority(69·57%)in the low-angle subjects.Conclusion　Owingtothe obvious characteristics ofmorphology in each cluster types and in each vertical facial skeletal types, different clinic considerationsmust be put forwardwhenwewanttomove the incisor.

Key words: normal occlusion, jawmorphology, cluster analysis