Poly(methyl methacrylate)/biphasic calcium phosphate (PMMA/BCP) coating has been prepared by mixing BCP in situ with the poly(methyl methacrylate) obtained from methyl methacrylate (MMA) polymerization. For comparative studies, concentration of BCP into PMMA matrix was varied in order to determine the influence of BCP incorporation into PMMA matrix on the hardness and friction behavior. The micro-hardness of PMMA/BCP coatings on stainless steel was evaluated using a Vickers hardness tester, while the wear tests for PMMA/BCP coatings on stainless steel were carried out on a CSM tribometer in dry conditions with normal load of 2 N. The incorporation of BCP into the polymer matrix significantly improves the microhardness of PMMA increasing to 15 % with 0.25 wt.% of BCP content. Whereas, the lowest friction coefficient value µk = 0.35 was obtained for PMAA/BCP with 0.35wt.% of BCP.

In this work is discussed the synthesis of a novel antishrinking agent (SOC DA) and the evaluation of its performance in an acrylic dental resin. SOC DA was photopolymerized in conjunction with the components of a conventional acrylic resin, which includes a mixture of diacrylate monomers [glycerolate bisphenol A dimethacrylate (BIS-GMA) / Urethane dimethacrylate (UDMA) / triethyleneglycol dimethacrylate (TEGDMA)] in 50/30/20 molar ratio). SOC DA was added in a range between 5.0-20.0 mol % with respect to the total amount of moles of the acrylic monomers. It was found that increasing concentrations of SOC DA, promoted higher conversions of the dimethacrylate monomers without decreasing the photopolymerization rate of the acrylate monomers. The study of the effect of SOC DA on the mechanical properties of the dental composite filled with 70 % of silicon dioxide, revealed that the presence of the antishrinking agent improved both the compressive and the flexural strength of the dental materials. Besides, it was found that by using the SOC DA at 20%, the shrinkage was reduced 52%, compared with the same formulation without SOC DA.