Degree of conversion of bulk-fill compared to conventional resin-composites at two time intervals

Objective The purpose of this study was to assess the degree of conversion (DC) over time, using FTIR spectroscopy for bulk-fill flowable resin composite materials compared to conventional flowable and regular resin composite materials. Methods Eight resin composites were investigated including flowable bulk-fill materials SureFil SDR (SDR), Venus bulk-fill (VBF), x-tra base (XB), and Filtek Bulk Fill (FBF). Conventional flowable and regular composite materials included: Venus Diamond flow (VDF), Grandioso flow (GRF), Venus Diamond (VD), and Grandioso (GR). Degree of conversion (DC) was assessed by Fourier transform infrared spectroscopy using attenuated total reflectance technique. DC was measured for samples immediately post-cure (n = 3), and after 24 h storage period at 37 °C (n = 3). Results were analysed using one-way analysis of variance (ANOVA), Bonferroni post hoc test, and independent-samples t-test at α = 0.05 significance level. Results Immediately post-cure, the mean DC values of the different materials were in the following order: GRF > VDF > SDR > VBF > XB > GR > FBF <VD and ranged from 34.7 to 77.1%. 24 h post-cure, DC values were in the following order: GRF > VBF > VD > SDR > VDF > GR > XB <FBF and ranged from 50.9 to 93.1%. GRF showed significantly higher DC values than all other materials at both time intervals while XB and FBF showed significantly lower values at 24 h post-cure. Significance The 24 h post-cure DC values of the bulk-fill composites SDR and VBF are generally comparable to those of conventional composites studied; however, the 24 h post-cure DC values of XB and FBF were lower compared to the other materials.