Abstract
It is known that occlusal interference is related to some systemic symptoms. However, there are few reports on the mechanisms of these systemic symptoms. In particular, the mechanisms for abnormality of the autonomic nervous system induced by occlusal interference still remain unclear. This study was designed to examine the influence of occlusal interference on the autonomic function and to clarify its mechanisms in 52 unanaesthetized rats. The blood pressure was measured as one of the autonomic functions, from the caudal artery by the tail-cuff method before, during and after insertion of bite-raising splints. The unilateral bite-raising splints (1, 2 or 3mm in vertical dimension) were set on the upper teeth to produce an occlusal interference to be sustained for 20 days. The blood pressure of the 1mm unilateral bite-raising group did not change significantly between before and during insertion of the splints. Unilateral bite-raising of 2mm and 3mm resulted in a significant increase of blood pressure. After removal of the splints, the blood pressure returned to the pre-insertion level. Unilateral bite-raising also produced a statistically significant reduction of the body weight during insertion period of the splints. However, when the effect of fasting on the blood pressure was examined, the blood pressure did not change significantly, whereas the body weight decreased remarkably during fasting. This result indicates that the increase of blood pressure depended primarily on unilateral bite-raising. Furthermore, α- and β-adrenergic antagonists, prazosin and propranolol, respectively, were used to determine the mechanisms of increase of blood pressure induced by occlusal interference. The increased blood pressure decreased significantly after the administration of prazosin. There was no statistically significant difference of heart rate between before and after administration of prazosin. Propranolol also significantly reduced the blood pressure, however, no statistically significant difference was observed in the heart rate. The result suggests that activation of the autonomic nervous system is involved in the increase of blood pressure induced by insertion of unilateral bite-raising splints, and that the increase of blood pressure induced by occlusal interference is mediated by activation of the sympathetic nervous system.
