Bioactive composites containing TEGDMA-functionalized calcium phosphate particles: Degree of conversion, fracture strengthand ion release evaluation

Abstract

Objective. To evaluate the strength and ion release of experimental composites containingTEGDMA-functionalized calcium phosphate particles.Methods. Seven composites containing equal parts (in mols) of BisGMA and TEGDMA and60 vol% of fillers were manipulated. Filler phase was constituted by silanized barium glassand 0% (control), 10% or 20% (volume) of dicalcium phosphate dihydrate (DPCD) particles,either non-functionalized or functionalized with two different TEDGMA contents. DCPDparticles were synthesized and characterized by X-ray diffraction (XRD), elemental analysis,surface area and dynamic light scattering. Composites were tested for degree of conversion(DC) by near-FTIR. Biaxial flexural strength (BFS) was determined after 24 h and 28 days inwater. Calcium and phosphate release after 7 days was assessed using inductively coupledplasma optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey test(alpha:5%).Results. XRD confirmed the crystalline structure corresponding to DCPD. Elemental analysisrevealed particles with zero, 14% or 22% TEGDMA, with similar D50(around 19 m) andsurface areas from 3.5 to 11.4 m2/g. The presence of DCPD did not reduce DC. After 24 h,functionalization (both 14% and 22% TEGDMA) improved composite strength in comparisonto non-functionalized DCPD, both at 10% and 20% levels. After 28 days, BFS of materialscontaining 10% functionalized DCPD were statistically similar to the control containing onlybarium glass. Among composites containing 10% DCPD, particle functionalization with 14%TEGDMA did not jeopardize ion release.