Local opioids in a model of periodontal disease in rats.

There is growing evidence for the participation of opioid receptors in the development of inflammation. The present study was designed to clarify the role played by opioid receptors in periodontal disease. Periodontal disease was induced by placing a sterile silk ligature around the cervix of the second maxillary tooth on day 0. Morphine was administered either systemically or locally before and after the onset of periodontal disease. The results showed that in both patterns, morphine treatment reduced fiber attachment and alveolar bone loss, without affecting the increased leukocyte count in the gingivae. Naltrexone, a specific opioid antagonist, reversed the inhibitory effects induced by morphine in diseased rats, while the increased number of inflammatory cells remained unaffected. These results point to a possible role for local opioids in experimental periodontal disease.