Orthodontic tooth movement in cholestatic and cirrhotic rats

To investigate whether cirrhosis and cholestasis could influence orthodontic tooth movement.

Basic science, animal experimental study.

This study was conducted in the Department of Pharmacology, School of Medicine at Tehran University of Medical Sciences in 2007.

A total of 40 male Sprague-Dawley rats (150-200 g) were divided into five experimental groups: non-operated, cholestatic-sham, cirrhotic-sham, cholestatic and cirrhotic groups.

An orthodontic appliance, consisting of a 5 mm nickel titanium closed coil spring, was ligated between the maxillary right incisor and first molar of each rat to deliver an initial force of 60 g. The cholestatic and cirrhotic groups underwent a bile duct ligation operation and received an orthodontic appliance for 7 days (cholestatic group) and 28 days (cirrhotic group) after surgery. Two other groups underwent a sham operation and had an orthodontic appliance inserted after 7 (cholestatic-sham) and 28 days (cirrhotic-sham). A fifth control group underwent neither bile duct ligation operation nor sham operation.

The cirrhotic group showed significantly increased orthodontic tooth movement (OTM), compared to all other study groups (P<0.001). The mean OTM in the cholestatic group was significantly higher than in the other three groups (two sham groups and unoperated one) (P<0.01). Bone density was also significantly decreased in the bile duct ligated (cirrhotic and cholestatic) groups (P<0.01).

Our data demonstrated that biliary cirrhosis could cause a significant increase in the OTM and decrease in the bone density in rats, though there was no significant alteration in bone resorption or osteoclasts detected in such animals.