Determination of dimensions and angles of mandible in the fetal period

The aim of the present study was to determine the dimensions of the mandible during the fetal period, the relationship between the growth rates of the angle of the mandible and the dimensions of the mandible. Furthermore the angle of union of the two halves of the body of the mandible on the horizontal mandibular plane, which was not described elsewhere, is explored in this study. One hundred and sixty-one human fetuses (83 males and 78 females) without any cranio-facial or mandibular asymmetry, external pathology or anomaly and aged between 9 and 40 weeks of gestation were used in the study. Cases were stratified into four groups according to their developmental ages, that is, first trimester, second trimester, third trimester, and term fetuses. Cranio-facial parameters in addition to bi-condylar, bi-gonial, bi-mental tubercular, condyle-gonion, gonion-mental tubercle, condyle-mental tubercle, gonion-pogonion distances were measured. The degree of the angle of the mandible, angle of union of the two halves of the body of the mandible and sagittal length of the base of the mandible were calculated. The means of the parameters with respect to gestational weeks and groups were computed. While there were no sex differences in any of the parameters (P>0.05) there were very significant relationships between gestational age and parameters (P