A Histologic Investigation of Orthodontic Tooth Movement in Hypothyroid Macaque Speciosa Monkeys

Abstract

This study was undertaken to histologically evaluate orthodontic tooth movement in hypothyroid and in normal Macaque speciosa monkeys. The experimental animals were rendered hypothyroid by radiosurgically altering the thyroid gland. A clinically acceptable orthodontic force was delivered to the anterior teeth of the monkeys. After the desired movement, a histologic investigation was made to correlate tissue responses with pressure, tension and root resorption. There was no significant difference among the three experimental animals. Likewise, there was no significant difference between the control animal and the three experimental animals. Osteoblastic and osteoclastic activity occurred to a comparable degree in both the experimental and control animals and was within normal limits for the amount of orthodontic tooth movement achieved. Root resorption was evident in both orthodontically treated and non-treated teeth in both the experimental and control animals. The root resorption observed was not significantly different, quantitatively or strategically, between the experimental and the control animals. Repair of root resorption was evident in both the experimental and control animals.