Polymerization and shrinkage kinetics and fracture toughness of bulk-fill resin-composites

To determine degree of conversion (DC), maximum polymerization rate (RPmax), shrinkage (PS), (PS Rmax) and fracture toughness (KIC) different types bulk-fill (BF) composites plus the effect viscosity reduction techniques. BF specimens were created in 2 mm deep molds: SonicFill 3 (SF3), Viscalor (VC), One Bulk Fill (OBF) Beautifil (BBR). SF3 was applied via sonic insertion using a handpiece (Kerr Corp. USA). pre-heated Caps Warmer T3 mode (at 68 °C) for 30 s (T3–30 s) min (T3–3 min), respectively. Specimens irradiated at zero distance from upper surface with an Elipar S10 LED unit (3 M ESPE, USA) mean irradiance 1200 mW/cm2 40 s. Real-time kinetics DC 5 24 h post-irradiation (DC5 DC24 h) measured ATR-FTIR (n = 3). PS up to 1 on thick discs bonded-disk technique 3) Rmax obtained by numerical differentiation For toughness, single-edge-notched (32 × 6 ×3 mm) each composite prepared three-point bending after 7 d water storage 5). Data analysed One-way ANOVA, independent T-tests Tukey post-hoc tests (p < 0.05). showed significantly highest DC5 min, RPmax 0.05), followed OBF Regardless pre-heating, VC comparable BBR > There no significant difference these composites, except had However, varied among materials 0.047) Rmax. Regarding lowest KIC whereas other similar Strong correlations filler content (wt%)-PS/KIC found. Different pre-heating times influences %, RPmax, PS, Significance. shrinkage. A highly filled giomer (BBR) others KIC. Pre-heating adverse effects properties. Sonication are beneficial techniques enhance flowability without either increasing or reducing toughness.