Root growth in the teeth of 46,XY females.

The subjects of this study are women with a male sex chromosome complement or 46,XY females who show the complete form of the testicular feminization syndrome (CTF). The basic endocrine defect is end organ insensitivity to androgens. They are on average tall individuals and also show an increase in head and face dimensions relative to normal females. A size increase is likewise evident in permanent tooth crowns and here we report permanent tooth root lengths in eight 46,XY females, their five female relatives and population control females and males. Measurements were made from panoramic radiographs by a digital calliper according to established procedures on both sides of the jaws. The results show increased root lengths of 46,XY females relative to control females with values similar to those in population control males. The root and crown findings point to evident irreversible growth excesses in 46,XY females beginning 3 years after birth up to the age of 14 years expressing an effect which apparently is influencing in a continuous way. Excess root growth conceivably would develop independently of the possible androgen influence, and it is suggested that the increase results from the direct effect of the genes on the Y chromosome. It is possible that these genes on the Y chromosome are the same that promote tooth crown growth.