Physicochemical effects of nano type-B bone substitute on pulp protective cement formulations

The current research investigated the effects of the addition of nano-carbonated hydroxyapatite (nCHAp) along with influences on physioterico-chemical properties that are applicable to vital pulp therapy in mineral trioxide aggregate (MTA Angelus). Settling time and solubility analyses, pH, compressive strength and surface microhardness were carried out in samples containing 1, 2, 3, 4, and 5 wt% nCHAp. Results were proven to be concentration-dependent, where the 3% nCHAp provided the best results with a significant increase of setting time (64%), decreasing solubility to 0.88±0.15% (672 h), and pH was maintained greater than 9.2 during the 28 days, together with a considerable enhancement of compressive strength (74.00±1.33 MPa) or surface microhardness (78.12±0.97 kg/mm2 at 28 days). High concentrations (more than 4%) had a negative influence on both mechanical stability and the pH stability, a fact related to particle agglomeration and over-substitution. The findings indicate that incorporation of 3% nCHAp into MTA enhances its physicochemical characteristics without altering the main features needed in pulp therapy.