Effects of Transmucosal Thyroxine Administration on the Tooth Movement in an Animal Model

Objective The aim of this study was to investigate the effects of transmucosal administration of thyroxine on the tooth movement and osteoclastic activity in Beagle dogs. Materials and Methods Eight Beagles were randomly divided into control group ( n = 4) and thyroxine group (4-week group, n = 2 and 8-week group, n = 2). Buttons were bonded on the labial surfaces of the second premolar and anchorage teeth. Nickel-titanium closed-coil springs were connected. In the thyroxine group, thyroxine tablets were bonded to the hooks attached to the second premolar. Results The mean rate of orthodontic tooth movement (OTM) in the thyroxine group was slightly higher than that in the control group. Microscopic evaluation showed that the number of osteoclasts in the thyroxine group significantly increased. Conclusion The protocol for transmucosal administration of thyroxine could not significantly accelerate OTM. An increase in the number of osteoclasts was observed through microscopic evaluation during the 4 th week.