Effect of synthetic amorphous calcium phosphate nanoparticles on the physicochemical and biological properties of resin-modified glass ionomer cements.

The aim of this study was to find an optimum dose of the synthetic amorphous calcium phosphate (ACP) nanoparticles to be incorporated in resin-modified glass ionomer cements (RMGICs) for triggering the release of PO43-/Ca2+, alkaline phosphatase (ALP) activity and osteogenic differentiation of mesenchymal stem cells (hMSCs) without significantly affecting the essential properties of the cements. RMGICs were formulated from the powder composed of melt-derived strontium fluoro-aluminosilicate glass (SFAG) and synthetic ACP nanoparticles (0-20 wt%), as well as commercial polyalkenoic acid liquid. The effect of ACP incorporation on the workability, microstructure, Ca2+/PO43-/F- ion release and compressive strength was investigated. The response of hMSCs to the optimized cements was assessed by MTT cytotoxicity, ALP activity, and staining tests. The working time of the formulated RMGICs decreased significantly upon increase of ACP content from 5 to 20%. ACP (5%)-incorporated RMGICs showed improved photopolymerization and setting. An insignificant reduction was recorded in the compressive strength of RMGICs with addition of 1.5-5% ACP. The fluoride release didn't significantly decrease due to addition of 5% ACP. Upon incorporating 5% ACP, the biocompatibility of RMGICs rose to about 20%. In addition, ALP activity and osteogenic differentiation of hMSCs noticeably increased after exposure to ACP-incorporated RMGIC. ACP (5%)-incorporated RMGICs could be promising candidates for both restorative and regenerative dentistry owing to the optimum mechanical strength, prolonged ion release, and their effective role in the cell differentiation and biomineralization demanded for pulp regeneration.