Effect of nicotine on orthodontic tooth movement and bone remodeling in rats

Abstract

Objective To quantitatively analyze the effect of nicotine on orthodontic tooth movement (OTM) and bone remodeling in rats using micro-computed tomography and tartrate-resistant acid phosphatase immunostaining. Methods Thirty-nine adult male Sprague–Dawley rats were randomized into three groups group A, 0.5 mL normal saline (n = 9, 3 per 3, 7, and 14 days); group B, 0.83 mg/kg nicotine (n = 15, 5 per 3, 7, and 14 days); and group C, 1.67 mg/kg nicotine (n = 15, 5 per 3, 7, and 14 days). Each animal received daily intraperitoneal injections of nicotine/saline from the day of insertion of identical 30-g orthodontic force delivery systems. A 5-mm nickel-titanium closed-coil spring was applied between the left maxillary first molar (M1) and the two splinted incisors. The rate of OTM and volumetric bone changes were measured using micro-computed tomography. Osteoclasts were counted on the mesial alveolar bone surface of the distobuccal root of M1. Six dependent outcome variables, including the intermolar distance, bone volume fraction, bone mineral density, trabecular thickness, trabecular volume, and osteoclast number, were summarized using simple descriptive statistics. Nonparametric Kruskal–Wallis tests were used to evaluate differences among groups at 3, 7, and 14 days of OTM. Results All six dependent outcome variables showed no statistically significant among group-differences at 3, 7, and 14 days. Conclusions The findings of this study suggest that nicotine does not affect OTM and bone remodeling, although fluctuations during the different stages of OTM in the nicotine groups should be elucidated in further prospective studies.

Effect of cigarette smoking on alveolar bone thickness and density in patients undergoing leveling and alignment of crowded lower anterior teeth: a controlled clinical trial

“…They are also in agreement with the results of a review conducted by Yoon et al., 47 which showed that tobacco consumption is a risk factor for bone fractures regardless of body mass and bone density. However, the results of the present study differ from the results of a study by Lee et al., 48 which was conducted on experimental animals and showed no effect of nicotine on bone remodeling during orthodontic tooth movement. The reason for the difference in the study findings may be because their study was conducted on experimental animals.…”

“… 49 – 51 These results are similar to the results reported by Rosa et al., 52 who showed that smoking had a detrimental effect on both alveolar bone height and density when comparing smoking students and nonsmokers. Additionally, our findings are similar to the results of the above-mentioned review conducted by Yoon et al., 47 which showed that smoking is associated with decreased bone density depending on the duration and dose of smoking, whereas they differ from the results of the study by Lee et al., 48 which showed no effect of nicotine on alveolar bone density during orthodontic movement. As noted above, the reason for this discrepancy can be because this study was conducted on experimental animals.…”