Developmental advancement of the male dentition in the first trimester.

During postnatal development the female is more advanced than the male in calcification and eruption of all permanent teeth, except for the third molar. In deciduous teeth the direction is reversed; males are slightly more advanced (H. V. MEREDITH, J Dent Res 25:4366, 1946). The direction and the magnitude of prenatal dental dimorphism is of interest, but has not been systematically explored. When reviewing first-trimester human embryos, abnormal specimens were excluded after gross and microscopic examinations. Histologic sections of 52 males and females were then available in the 14 to 58 mm crown-rump (C-R) range. The embryos were matched for sex and for size within + 1.0 mm and comparisons of dental development were made on a matched basis. Except for the embryos where suitable sex and size matches could not be made, males were advanced in all deciduous