Effects of nicotine on osteogenesis

Abstract

The purpose of this study was to demonstrate the inhibiting effects of systemically administered nicotine on osteogenesis and angiogenesis. The orthopedic expansion of a suture is a non-invasive method directly related to orthodontic treatment. This study examined the actions of nicotine related to the vascularly related osteogenic response elicited by orthopedic expansion. Sixty seven male,6-8 week old, Sprague-Dawley received 2 different dosages of nicotine (6 and 12 mg/kg/day), for a period of 14 days. Nicotine was delivered subcutaneously with the use of Alzet® Osmotic minipumps. Control animals received minipumps filled with saline. Fluorochrome labels were administered during the two-week period to mark bone formation. Ten days after minipump implantation a second surgery was performed and ring-type elastic separators were placed between the maxillary central incisors of forty-six animals. Twenty-three and ninety-five hours after expansion the animals were injected BrdU and terminated 1 hour later. The maxillae were demineralized and embedded in paraffin. The femurs and tibias were cleaned from soft tissue and embedded in methyl methacrylate. The results of this study indicate that nicotine has a dose-dependent inhibiting effect on both the osteogenic and angiogenic process in the expanded suture. After 96 hours of expansion these effects are only partially reversed. Nicotine inhibits vascular invasion and depresses osteoblast recruitment. The study indicated that there may also be a direct suppression of osteoblasts, but the principal anti-osteogenic effect of nicotine is an inhibition of the vascular proliferation and osteoblast histogenesis, associated with mechanically induced osteogenesis