title: The effect of thyroid hormone on orthodontic tooth movement in rats.
abstract: The major goals of this study were to determine the effects of different doses of thyroxin on the rate of orthodontic tooth movement and the force-induced root resorption. In this study fifty male Sprague--Dawley rats were divided into five groups: a normal group with no intervention; a control group in which appliances were placed and 10 ml/kg i.p./day normal saline was injected; and three thyroxin groups in which appliances were placed and 5, 10 and 20/microgram/kg i.p./day L-thyroxin were administered, respectively. A fixed orthodontic appliance consisting of a 5 mm closed-coil spring was ligated between the maxillary incisor and maxillary first molar to deliver an initial force of 60 gm. The results showed that administration of 20/microgram/kg i.p./day L-thyroxin significantly increased the amount of orthodontic tooth movement (p < 0.001). The extent of root resorption as seen from scanning electron micrographs decreased with thyroxin administration.
authors.affiliation: Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Shirazi
authors.forename: A R
authors.initials: AR
authors.lastname: Dehpour
authors.forename: F
authors.initials: F
authors.lastname: Jafari
mesh_terms: D015502:Absorptiometry, Photon; D000539:Alveolar Process / Q000187:drug effects; D000704:Analysis of Variance; D000818:Animals; D016723:Bone Remodeling / Q000187:drug effects*; D008297:Male; D008855:Microscopy, Electron, Scanning; D009967:Orthodontic Appliances; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013974:Thyroxine / Q000008:administration & dosage / Q000494:pharmacology*; D014086:Tooth Mobility; D014087:Tooth Movement Techniques / Q000379:methods*
chemical_list: D013974:Thyroxine