engleski

Physical, chemical and electrical properties of experimental composite materials based on amorphous calcium phosphate

Composite materials with amorphous calcium phosphate (ACP) release remineralizing ions that can be deposited in demineralized dental hard tissues and thus aid in the prevention of secondary caries. The main shortcomings of this class of experimental biomaterials are insufficient mechanical properties and fast degradation in the oral environment. The ACP-composites can be admixed with reinforcing fillers to improve mechanical properties and durability The aim of this study was to investigate various properties of experimental ACP-composites that are important for their clinical applicability. Specifically, the effect of 10 wt% of reinforcing fillers comprising of barium glass and silica on the degree of conversion (DC), depth of cure, optical properties, and temperature rise during light curing were investigated. Additionally, a novel approach using impedance spectroscopy was used to explore the polymerization kinetics and microstructural characteristics of ACP-composites. ACP-composites attained very high DC (about 80%), and the DC was not considerably diminished by the addition of inert fillers. Curing efficiency at depth for ACP-composites was comparable to that of conventional composites, with depths of cure of 2-3 mm. Temperature rise that was produced during light curing of ACP-composites was no more harmful to dental pulp than that of conventional composites. Light transmittance of ACP-composites was in the range of conventional composites. Real-time light transmittance measurements were shown to provide useful information on polymerization kinetics. ACP-composites have shown different polymerization kinetics than the materials that contain only reinforcing fillers, with possible consequences on polymerization shrinkage and polymeric network structure. Impedance spectroscopy was demonstrated as a valuable tool for investigating various characteristics of ACP-composites. Impedance data used for describing the extent of polymerization correlated well with the DC data obtained by Raman spectroscopy. Kinetic parameters obtained by impedance measurements correlated well with light transmittance. Impedance measurements proved to be useful for quantifying the amount of water introduced to the composite by ACP fillers.

amorphous calcium phosphate ; remineralizing composite ; degree of conversion ; light transmittance ; temperature ; impedance spectroscopy

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