Purpose: To evaluate histopathologically the dental pulp response to bioactive glass nanoparticles in the resin composite restoration and the adhesive as a direct pulp capping material regarding inflammatory cell infiltrate, hard tissue formation and Pulp tissue disorganization. Material and methods: Four mongrel male dogs were selected for this study with a total of 40 teeth were divided into two groups (n=20) according to the treatment protocol (P); (P1) treated with light cured calcium hydroxide (control group) and (P2): treated with resin composite and its adhesive containing bioactive glass. The histopathological findings were studied for each specimen at two times intervals (T); (T1) fourteen days and (T2) sixty days. Split mouth technique was followed. The manufacturer's instructions were followed during applying the materials. Animals were sacrificed at each time interval and teeth were collected for histopathological finding. Results: adhesive and resin composite restoration containing bioactive glass group showed significantly less inflammatory cell infiltrate, less pulp tissue disorganization and better calcific bridge formation than Calcium hydroxide group. When the effect of time was considered, inflammation was significantly decreased from fourteen days to sixty days while hard tissue formation was significantly increased for both materials. Also pulp tissue disorganization was decreased significantly and showed more normal pulp tissue morphology from fourteen days and to sixty days. Conclusion: resin composite restoration and its adhesive containing nanoparticles of bioactive glass could be used as a direct pulp capping material.