Mechanical properties of experimental composites containing bioactive glass after artificial aging in water and ethanol.

Abstract

To evaluate the effect of bioactive glass 45S5 (BG) in experimental composites on flexural strength (FS), flexural modulus (FM), modulus of resilience (MR), and material reliability after artificial aging in water for 1, 7, and 30days, and an additional accelerated aging for 3days in a 75vol% ethanol-water solution. Five experimental light-curable composites were prepared with 0-40wt% of BG and a total filler load of 70wt%. The resinous matrix was Bis-GMA/TEGDMA in 60:40 by weight. Mechanical properties were evaluated using a three-point bending test (ISO/DIN 4049:1998) with n = 20. Weibull statistics were used to assess material reliability. Additionally, the degree of conversion (DC) was assessed 24h post-cure using FT-Raman spectroscopy. FS and FM decreased linearly as the amount of BG was increased. The ISO 4049 requirement for a minimum FS of 80MPa was fulfilled in experimental composites with up to 20wt% of BG. Degradation of FS and FM with artificial aging was more extensive in materials with higher BG amounts. MR decreased as a function of BG amount and artificial aging. Material reliability (Weibull modulus) was stable through aging for composites with up to 10wt% of BG. DC was negatively influenced by the BG amount and ranged from 64 to 81%. Increasing the amount of unsilanized BG fillers from 0 to 40wt% resulted in a progressive decline in mechanical properties and a more extensive degradation during artificial aging. Bioactive fillers diminished the mechanical properties in a dose-dependent manner.