The incidence of third molar absence in the subjects with different vertical skeletal face types / 实用口腔医学杂志

ABSTRACT

Objective:To survey the relation of different vertical skeletal facial type and the third molar agenesis.Methods:The vertical face type of 207 subjects was divided into high angle(n=45),average angle(n=99)and low angle(n=63)groups by the assessments of MP-SN angle.The assessment of the third molar was made from panoramic radiographs,then the third molar agenesis rate of different vertical skeletal facial types was analysed.Chi-square criterion examination was conducted with SPSS 17.0 software. Results:In the high angle group,whether in the maxillary or mandibular,unilateral or bilateral,the absent percentage of third molar was higher than that in low angle group(P<0.05).In the females the bilateral maxillary third molar absent percentage was higher than in the males(P<0.05).The absent percentage of maxillary third molar was higher than that of the mandibular third molar(P<0.05).Conclusion:The third molar absence depends on vertical skeletal facial type.The absent percentage of third molar in the in-dividuals with high angle type is higher than that in those with low angle type(P<0.05).