The purpose of this study was to identify the difference of vertical movement of mandible according to Angle´s molar relationship and by skeletal factors affect to vertical movement of mandible. 172(age ranged from 20 to 30) subjects who go to college within territory of Kwangju city without any experience of temporomandibular disorder, extraction and orthodontic treatment. were selected for this study. The subjects were classified into class Ⅰ(male:30, female:49), class Ⅱ(male:18, female:24) and class Ⅲ(male:18, female:33) according to Angle´s molar relationship. The distance was measured between incisal edge of maxillary and mandibular central incisor and between bottom of central fossa of maxillary and mandibular 1st molar with ruler. The arch length and width were measured on the diagnostic cast. Cephalometrics were taken and traced. Landmarks were identified and analyzed.
1. Maximal interincisal opening of male is larger than that of female in class Ⅰ, class Ⅱ and class Ⅲ. Among each group maximal interincisal distance is the largest in class Ⅲ. Maximal intermolar distance of male is superior to that of female in class Ⅰ, class Ⅱ, and class Ⅲ, but there is no significant difference among them.
2. On maximal opening movement of Angle´s classification class Ⅰ, class Ⅱ, total mandibular length, mandibular ramal length, mandibular inferior border length and upper arch width were important variables and facial length, upper arch length and lower arch length had negative relationship to that. On maximal opening movement of Angle´s class Ⅲ, the upper arch length, the lower arch length and anterior facial length were important variables especially when compared with class Ⅰ and Ⅱ, and upper arch width had negative relationship.
There results suggest that maximal opening movement is affected by facial morphology in all classes, but each group is affected by different facial skeletal variables. Accordingly, facioskeletal variables might be considered as diagnosis and treatment to improve the amount of mouth opening.
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