Abstract

The purpose of this study was to investigate the effects of dietary L-arginine as nitric oxide (NO) precursor on orthodontic tooth movement in rats. 36 male ten-week old Wistar rats were randomly divided into experimental and control groups. The experimental group received 2% (w/w) dietary L-arginine in drinking water six days before the insertion of springs to elevate their blood level. On the seventh day, in both groups, maxillary incisors was moved by the insertion of springs and 12 days after insertion of springs, the rats were sacrificed, then the mesioincisal distance between maxillary incisors was measured. Afterwards, 12 and six rats from both groups were selected randomly for preparing histological section to count osteoclasts under a light microscope and for examining the surface area of root resorption lacunae under a scanning electron microscope, respectively. The data on the extent of orthodontic tooth movement and the number of osteoclasts were analyzed by independent sample t test and findings on root resorption were analyzed by using Mann-Whitney U test. The results showed that in L-arginine group, the orthodontic tooth movement (p < 0.001) and the number of osteoclasts (p < 0.05) were significantly higher when compared with the control grou. However, there was no significant difference between the two groups in terms of the surface area of resorption lacunae.

Key words: L-Arginine, dietary, orthodontic tooth movement, nitric oxide, root resorption, osteoclast, nitric oxide synthase (NOS).