Effect of alendronate on orthodontic tooth movement in rats.
BACKGROUND
Osteoclastic activity is required for orthodontic force to move teeth through alveolar bone. Bisphosphonates are drugs that inhibit osteoclast maturation, function, and survival. The aim of this study was to assess orthodontic tooth movement in rats receiving bisphosphonate treatment.


METHODS
Two groups of Sprague-Dawley rats were used. The rats in the treatment group received 7 mg per kilogram of body weight per week of alendronate sodium, and those in the control group received no drugs. A coil spring exerting a constant 50-g force was activated across the span from the central incisors to the first molar. As the first molar tipped mesially, a diastema between the first and second molars was created. Vinyl polysiloxane impressions were poured in die stone, and the diastema was measured indirectly with a charged-couple device microscope camera and Optimas software (Media Cybernetics, Newburyport, Mass).


RESULTS
Statistical analysis with repeated-measures analysis of variance showed less orthodontic tooth movement in the alendronate group compared with control group (0.06 vs 0.24 mm at 2 weeks, and 0.45 vs 1.06 mm at 4 weeks; P = 0.0004 for the alendronate vs control main effect).


CONCLUSIONS
This study demonstrated an inhibitory effect of alendronate administration on orthodontic tooth movement in a rat model.
Karras
Jeremy C
JC
Assistant professor, Division of Orthodontics, School of Dentistry, University of Minnesota, Minneapolis, USA. karrasjr@yahoo.com
Miller
James R
JR
Hodges
James S
JS
Beyer
John P
JP
Larson
Brent E
BE
D019386:Alendronate / Q000494:pharmacology*; D000539:Alveolar Process / Q000187:drug effects*; D000704:Analysis of Variance; D000818:Animals; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D016723:Bone Remodeling / Q000187:drug effects*; D008437:Maxilla / Q000187:drug effects; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D014087:Tooth Movement Techniques
D050071:Bone Density Conservation Agents; D019386:Alendronate