<b>Histological evaluation of the rat dental pulp after indirect capping with sildenafil or L-NAME incorporated into a bioadhesive thermoresponsive system

Abstract

 We evaluated the histological dental pulp state in vivo after indirect pulp capping using sildenafil or L^G-nitro-L-arginine (L-NAME), incorporated into a new bioadhesive thermoresponsive system (BTS). Male Wistar rats were subjected to an upper and lower first molar class I cavity preparation followed by indirect pulp capping with sildenafil or L-NAME. Calcium hydroxide (CaOH₂) was used as a control. The teeth and surrounding bone were properly dissected and processed for Nissl’s staining. Pulp state was evaluated considering the morphological aspects of the inflammatory response, type of inflammatory infiltrate, organization of the odontoblast layer, blood vessel condition, and presence of abscesses or necrosis. The results were expressed as average of observations. The most intense inflammatory response was observed 3 days after the cavity preparation. No identified changes were detected in the dental pulp response of the molars treated with L-NAME compared with those treated with CaOH₂. A dual effect was observed in the teeth treated with sildenafil. While low sildenafil concentration (0.015% w w^-1) promoted effects comparable to CaOH₂, at a higher concentration (0.15% w w^-1), sildenafil caused a severe inflammatory response and pulp necrosis. This pioneering suggest that NO pathway activity may be a determinant in the process of dental pulp healing.