RESUMO
OBJECTIVE: To quantify COX-2 mRNA in lesions of chronic apical periodontitis and relate the findings to the histological findings. METHODS: A total of 13 periapical lesions including 10 periapical granulomas and 3 periapical cysts were obtained. Normal periodontal ligament tissues from extracted third molars were used as control tissues. The expression of COX-2 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) technique. The relationships between the expression of COX-2 mRNA and histological findings (including the type of histology, the degree of inflammatory infiltrates), the size of radiolucent of the lesions and the clinical findings of the involved tissues were analyzed. The expression of COX-2 at cell level was detected by immunohistochemistry. RESULTS: A significant higher level of COX-2 mRNA was found in periapical granulomas and in periapical cysts , but no significant difference was detected between those two groups. COX-2 mRNA in the group with moderate inflammation cell infiltration was higher than that of light and heavy inflammation cell infiltration (0.76+/-0.11 vs 0.11+/-0.01, 0.76+/-0.11 vs 0.23+/-0.06, P<0.05). The elevated COX-2 mRNA levels were detected in lesions with clinical symptoms. COX-2 -positive cells were detected in the epithelial cells and inflammatory cells. CONCLUSION: COX-2 might play more important roles in the pathogenesis and development of periapical lesions.