Hormonal Control of Tooth Eruption

Abstract

Replacement therapy in hypophysectomized rats served to identify the individual hormones controlling their odontogenic defects. It had the same qualitative effect shortly after the operation as well as after long postoperative intervals. Growth hormones resulted in an increase in size without hastening the eruption rate. In the young as well as the old groups the latter remained identical with that in the untreated hypophysectomized controls. Histologically, a "rejuvenation" of the connective tissues, without activation of amelo-genesis, was observed. Admn. of growth hormone to intact animals had similar effects. Thyroxin treatment increased the tooth dimensions and accelerated the eruption rate 36% in the young groups and 46% in the old group. Amelogenesis showed an improved pattern, and the vascularization of the tissues was restored. The combination of both hormones showed opt. effects on eruption rate, and growth was characterized histologically by an amazing restoration of the completely atrophied enamel organ. These observations thus lead to the conclusion that tooth eruption is presided over by the synergism of 2 hormones: the pituitary growth hormone, which stimulates the basic process of growth, and the thyroid hormone, which controls differentiation or maturation.