A study in 47,XYY men of the expression of sex-chromosome anomalies in dental occlusion.

Occlusal traits were determined for 47,XYY men and compared with previous determinations of occlusal morphology in other sex-chromosome anomalies and in normal women and men. The 47,XYY men, like 47,XXY men, tended to have a mesial molar occlusion and a mandibular overjet more often than did other groups, while 45,X women (Turner patients) clearly had the highest frequency of distal occlusion and large overjet. The 47,XXY men had the highest frequency of most occlusal anomalies. As a whole, these and earlier findings suggest that the number of X or Y chromosomes is associated negatively with distal occlusion and lateral crossbite, whereas a positive association was found with mesial molar occlusion and scissors bite.