Localization of nitric oxide synthase in the periodontal tissues of orthodontically moved and stationary teeth

Abstract

There is ample evidence that the inflammatory response and vascular supply of the periodontal tissues is crucial to mediating the effects of applied force. The connection between mechanical forces and vascular activity, however, is not well defined. Nitric oxide (NO), a molecule only recently recognized as a chemical messenger within biologic systems, has been shown to be central to these processes in many parts of the body, but not during tooth movement. Therefore, the aim of this investigation was to identify the sites of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) activity in the periodontal tissues of moved and stationary teeth immunohistochemically. Our data show that the periodontal tissues of stationary rat molar teeth exhibit the presence of less eNOS and iNOS. There is an increased amount of eNOS produced after rat molar tooth movement in blood vessel walls. Similarly, increased amounts of iNOS produced after rat molar tooth movement in the periodontal ligament and connective tissue between roots of moved teeth as well as around blood vessels could be seen. The presence of eNOS and iNOS was consistently seen in the odontoblast layer of pulp chambers of moved and stationary teeth. Our results indicate a possible role of NO in periodontal remodeling during tooth movement.