Effect of nitric oxide inhibitor and donor substances on the inflammatory process caused by endodontic irrigants

Nitric oxide (no) has been considered a key molecule in inflammation. objective: the aim of this study was to evaluate the effect of treatment with l-name and sodium nitroprussiate,substances that inhibit and release no,respectively,on tissue tolerance to endodontic irrigants. material and methods: the vital dye exudation method was used in a rat subcutaneous tissue model. injections of 2% evans blue were administered intravenously into the dorsal penial vein of 14 male rats (200-300 g). the no inhibitor and donor substances were injected into the subcutaneous tissue in the dorsal region,forming two groups of animals: g1 was inoculated with l-name and g2 with sodium nitroprussiate. both groups received injections of the test endodontic irrigants: acetic acid,15% citric acid,17% edta-t and saline (control). after 30 min,analysis of the extravasated dye was performed by light absorption spectrophotometry (620 nm). results: there was statistically significant difference (p<0.05) between groups 1 and 2 for all irrigants. l-name produced a less intense inflammatory reaction and nitroprussiate intensified this process. conclusions: independently of the administration of no inhibitors and donors,edta-t produced the highest irritating potential in vital tissue among the tested irrigating solutions.