RESUMEN

Background: Recently, vital pulp therapy is widely used all over the world. It aims to maintain the viability and function of the injured dental pulp tissue. Direct pulp capping is recognized as one of the most common used techniques in this approach. Aim of the study: we aimed to compare the histopathological response of the dental pulp following direct pulp capping using two different capping materials; the exogenous nitric oxide (NOC-18) and Mineral Trioxide Aggregate (MTA) in dogs' teeth. Methods and materials: The pulp of thirty-two premolars and canines from four dogs (eight teeth per each dog) the pulp was exposed and treated with either exogenous nitric oxide (NOC-18) and MTA (four teeth in each group). The treated teeth were extracted and prepared for histologic evaluation after one month and three months, respectively. The histologic study evaluated the formation of dentine bridge, the degree of pulpitis, calcification of the coronal pulp tissue and odontoblasts layer activity. We have the ethical approval to achieve this research from the scientific committee in Faculty of Dentistry, Damascus University. Results: The results showed that the active statue of odontoblasts layer in NOC-18 group was significantly more than in MTA group after a month of recall (P: 0.003). No significant difference was found between MTA and NOC-18 categories in the formation of dentine bridge after 3 months (P: 1.000). Conclusion: Exogenous nitric oxide (NOC-18) maybe has a positive impact on formation of calcified bridge and efficacy of odontoblasts layer on directly capped dog's teeth. Exogenous NO donors might offer alternative to current pulp capping agents in Vital Pulp Therapy in endodontic.