Remineralizing amorphous calcium phosphate based composite resins: the influence of inert fillers on monomer conversion, polymerization shrinkage, and microhardness

Abstract

AimTo determine if the addition of inert fillers to a bioactive dental restorative composite material affects its degree of conversion (DC), polymerization shrinkage (PS), and microhardness (HV).MethodsThree amorphous calcium phosphate (ACP)-based composite resins: without added fillers (0-ACP), with 10% of barium-glass fillers (Ba-ACP), and with 10% of silica fillers (Si-ACP), as well as commercial control (Ceram•X, Dentsply DeTrey) were tested in laboratory conditions. The amount of ACP (40%) and the composition of the resin mixture (based on ethoxylated bisphenol A dimethacrylate) was the same for all ACP materials. Fourier transform infrared spectroscopy was used to determine the DC (n = 40), 20 min and 72 h after polymerization. Linear PS and Vickers microhardness (n = 40) were also evaluated. The results were analyzed by paired samples t test, ANOVA, and one-way repeated measures ANOVA with Student-Newman-Keuls or Tukey’s post-hoc test (P = 0.05).ResultsThe addition of barium fillers significantly increased the DC (20 min) (75.84 ± 0.62%) in comparison to 0-ACP (73.92 ± 3.08%), but the addition of silica fillers lowered the DC (71.00 ± 0.57%). Ceram•X had the lowest DC (54.93 ± 1.00%) and linear PS (1.01 ± 0.24%) but the highest HV (20.73 ± 2.09). PS was significantly reduced (P < 0.010) in both Ba-ACP (1.13 ± 0.25%) and Si-ACP (1.17 ± 0.19%) compared to 0-ACP (1.43 ± 0.21%). HV was significantly higher in Si-ACP (12.82 ± 1.30) than in 0-ACP (10.54 ± 0.86) and Ba-ACP (10.75 ± 0.62) (P < 0.010).ConclusionIncorporation of inert fillers to bioactive remineralizing composites enhanced their physical-mechanical performance in laboratory conditions. Both added fillers reduced the PS while maintaining high levels of the DC. Silica fillers additionally moderately improved the HV of ACP composites.

A review of bioceramics-based dental restorative materials

“…Among these nano-amorphous calcium phosphate (NACP) had been used in 15 studies 19,[21][22][23][24][25][26][27][28][29][30][31]57,58,62) , and the rest were based on micro-ACP. Moreover, zirconia 8,[32][33][34][35][36][37][38][39][40] and silica 8,39,41) had been hybridized with ACP to improve the mechanical and biological properties Nano-silver particles 27,57) and HA powder 42) were also mixed with ACP to analyze the antibacterial and mechanical properties, respectively. In vivo studies were found related to human 16,17) and rat models 18,19) .…”

Incorporation of Copper-Doped Mesoporous Bioactive Glass Nanospheres in Experimental Dental Composites: Chemical and Mechanical Characterization

“…The issue of secondary caries has enticed our research group to develop remineralizing bioactive materials with the addition of amorphous calcium phosphate (ACP) [ 3 , 4 , 5 , 6 ] and 45S5 bioactive glass (BG) fillers [ 7 , 8 , 9 , 10 , 11 ]. The supersaturated calcium and phosphate ion concentrations released by ACP resin composites have been shown to induce hydroxyapatite formation and remineralization [ 12 ].…”

“…Silica nanofillers (SiO 2 ) have been shown to enhance apatite formation on the surface of both ACP and BG composites [ 4 ]. However, the amorphous structure and solubility of ACP fail to provide strong mechanical properties of resin composites [ 3 , 4 , 5 ]. Similar behavior was demonstrated by BG resin composites, whose mechanical properties and degree of conversion (DC) deteriorated in a dose-dependent manner with the increase in BG ratio [ 8 , 10 ].…”

Review of nano‐technology applications in resin‐based restorative materials

“…119,120 Silanized inert fillers in the original ACP formulation Circumvented polymerization shrinkage, which is an undesirable consequence of high conversion rates. 38 Whiskers with nDCPA Fast release of Ca and PO 4 ions, due to the large surface area of the nDCPA particles, 119 which has been shown to re-precipitate and form hydroxyapatite inside tooth lesions outside the margins of the restoration. 121 Zirconia-silica clusters (0.…”