Microhardness and Compressive Strength of Bulk Fill Glass Hybrid Material and Other Direct Restorative Materials

Abstract

Background: This study aims to compare the compressive strength and microhardness of four tooth-colored restorative materials: bulk fill glass hybrid (GH), resin-modified glass ionomer (RMGIC), conventional glass ionomer (CGIC), and resin-based composite (RBC). Methods: Stainless steel molds were used to prepare 20 specimens for each material. Half of the specimens were subjected to 10,000 thermal cycles; the materials were subjected to compressive strength and microhardness tests. Mean values were statistically compared using a one-way ANOVA Test and Bonferroni pairwise comparisons. Results: GH (147.03 ± 20.19 MPa) had lower compressive strength than RBC (264.82 ± 30.95 MPa) but showed no significant difference with CGIC (130.19 ± 30.38 MPa) and RMGIC (183.52 ± 18.45 MPa). RMGIC’s compressive strength also significantly fell short of RBC (p < 0.05), but it significantly increased after thermocycling (160.14 to 183.52 MPa). As for microhardness, no significant difference was found between the groups. Thermocycling significantly increased the microhardness of CGIC (from 24.27 to 31.8 ± 2.66). Conclusion: Resin-based materials outperformed the other materials. Glass hybrid restorative material performed as well as resin-modified glass ionomer regarding compressive strength; however, further studies are necessary before considering glass hybrids for use as a permanent restoration.