Higher expression of galectin-3 and galectin-9 in periapical granulomas than in radicular cysts and an increased toll-like receptor-2 and toll-like receptor-4 expression are associated with reactivation of periapical inflammation.

INTRODUCTION: Cysts and periapical granulomas are inflammatory reactions that develop in response to periapical infection by microbial species in dental root canal. It is known that toll-like receptors (TLRs) are pathogen recognition molecules and that galectins are lectins that can be associated with the inflammatory process, stimulating or inhibiting the immune system. The objective of this study was to evaluate the in situ expression of TLRs and galectins in radicular cysts and periapical granulomas. METHODS: We analyzed 62 cases (30 radicular cysts, 27 periapical granulomas, and 5 control cases). Indirect immunohistochemistry was used to evaluate the expression of TLRs (TRL-2 and TLR-4) and galectins (Gal-3 and Gal-9). RESULTS: The expression of Gal-3 and Gal-9 was significantly higher in periapical granulomas and radicular cysts than in the control group. Similarly, both Gal-3 and Gal-9 were expressed significantly more in periapical granulomas than in radicular cysts. The expression of TLR-2 was significantly higher in periapical granulomas and radicular cysts than in the control group, and it was also significantly higher in radicular cysts with sinus tract than in the cases without sinus tract. Furthermore, the expression of TLR-4 was significantly higher in the cases of periapical granulomas with sinus tract than in the cases without sinus tract. CONCLUSIONS: Gal-3/Gal-9 and TLR-2/TLR-4 expression in the periapical granulomas and radicular cysts is associated with reactive periapical inflammation. Pathobiology of periapical disease is a very complex interplay of many bioactive molecules involved in immunoinflammatory responses. Up-regulation of these bioactive molecules might be an important modulator of inflammatory periapical lesions.

The effect of endodontic therapy on periapical exudate neutrophil elastase and prostaglandin-E2 levels.

This study aimed to investigate periapical exudate neutrophil elastase (NE) and prostaglandin E2 (PGE2) levels and their relationships with clinical symptoms, and to determine the changes of their levels following first treatment visit. Periapical exudate samples were collected from the canals of 34 nonvital single-rooted teeth at two sequential treatment visits. Periapical exudate NE and PGE2 levels were found to be higher in the presence of clinical symptoms (pus discharge, swelling) (p < 0.05). The canals of teeth with larger periapical radiolucent area (>or=1 cm) contained more PGE2 levels than with smaller ones (<1 cm) (p < 0.05). Periapical exudate NE levels were significantly correlated with PGE2 levels (p < 0.05), and their levels at first treatment visit did not change following root canal therapy (p > 0.05). The periapical exudate NE and PGE2 levels may regulate periapical disease expression, but the results of this study were unable to reveal this association.