DEVELOPMENT OF PERIRADICULAR LESIONS IN IMMUNOSUPPRESSED RATS

Problem. The role of bacteria has been well established in pulpal and periapical diseases, but the contribution of the host defenses is less clear. Objectives. The purpose of this study was to compare periradic ular lesion development in immunosuppressed rats with that in normal r ats. Study Design, Fifteen rats were given weekly injections of Cytoxa n (Bristol Laboratories) to suppress their immune systems. The pulps o f mandibular first molars of these animals and another 15 rats that ha d received no medications were exposed and left open to their oral flo ra. The rats were killed at 2, 4, and 6 weeks. Radiographic analysis w as performed by means of a computer linked to a digitizing board and s tylus. In addition, specimens were decalcified, sectioned, stained, an d examined under a microscope with a grid to quantify relative percent ages of surface areas of bone, root, periodontal ligament, marrow spac es, soft tissue, and inflammatory infiltrate. Results, Statistical ana lysis showed a significantly greater radiographic bone loss in the imm unosuppressed group only at 4 weeks. No significant histologic differe nces were found between the two groups. Conclusion. Our results sugges t that reduction of circulating leukocytes may not significantly affec t the development of periradicular pathosis in rats.