Sexual dimorphism in mesiodistal dentin and enamel thickness.

This study evaluates sexual dimorphism in mesiodistal diameter, enamel thickness and dentin thickness of the permanent posterior mandibular dentition in order to gain a better understanding of variation in mesiodistal tooth size. The results relate to a sample of 59 males and 39 females, 20-35 years of age. Bitewing radiographs of the right permanent mandibular premolars and molars were illuminated and transferred at a fixed magnification to a computer via a video camera. Enamel and dentin landmarks were identified and digitized on the plane representing the maximum mesiodistal diameter of each tooth. The results showed significant sex differences (p < 0.01) in mesiodistal diameter favouring males over females. Dimorphism was more pronounced for the molars than for the premolars. Enamel thickness, which is 0.4-0.7 mm greater for the molars than premolars, shows no significant sex differences. Dentin is significantly thicker in males than females, and is 3.5-4.0 mm thicker in molars than premolars. It is concluded that sexual dimorphism in mesiodistal tooth sizes is due to differences in dentin thickness and not enamel thickness.