Sexual dimorphism in the tooth crown dimensions of the second deciduous and first permanent molars of Taiwan Chinese.

Sexual dimorphism in the crown components in the second deciduous molar (dm2) and the first permanent molar (M1) of the dental casts taken from Chinese living in Kaohsiung (Taiwan) was investigated. Mesiodistal and buccolingual crown diameters, and 4 main-cusp sizes in the maxillary molars and mesiodistal diameters of the trigonid and talonid in the mandibular molars were measured using a digital caliper (0.01 mm). Percentage sexual differences were calculated. With the exception of trigonid mesiodistal diameters, the mean values of males were larger than females. In both of dm2 and M1 the mean values of the trigonid mesiodistal diameters were slightly larger in females than in males, but the differences were not significant. Percentage sexual dimorphism was smaller in the mesiodistal diameters than in the buccolingual in both dm2 and M1. The crown components showed larger sexual difference in dm2 than in M1, while in the maxilla the external crown size showed larger sexual difference in M1 than in dm2. The buccal cusps showed larger sexual difference than the lingual in the maxillary molars and the talonid showed larger sexual difference than the trigonid in the mandibular. Sexual dimorphism of dm2 and M1 in their crown components displayed similar pattern, although the different degree was noted. This result is thought to relate to the fact these molars belong to the first dentition embryologically.