Microhardness and Polishability of Bioactive-Glass Composites and Commercial Composite

Objectives: Composite dental restorations are composed of varying ratios of monomer and filler. The use of bioactive glass (BAG) as a filler in composite is of interest due to its antimicrobial properties and ability to release ions. Development of a BAG-containing composite may result in increased longevity of resin composite dental restorations. This study compared the microhardness and polishability of 12 novel BAG-containing composites with Empress Direct composite (Ivoclar Vivadent, Amherst, NY).
Methods: Twelve novel BAG-containing composites were fabricated using two different monomer mixtures; 2:1 or 3:1 EBPADMA:bis-GMA. Monomer mixtures contained either small, large, or a combination of small and large BAG particles (see Table 1). A custom PVS mold was used to fabricate 46 discs (10x2mm) from the composites on Table 1 (n = 3-5 each). Empress discs served as a control. All discs were light polymerized for 5 minutes using a Solidilite V light-curing unit (Shofu, Kyoto, Japan). Samples were aged in RO water for 24 hours (37°C). Discs were embedded in acrylic cylinders and polished with an Eco-Met 250 Polisher Grinder (Buehler, Lake Bluff, IL) finishing with P4000 grit paper.

Polishability (gloss) was measured using a Novo-Curve Glossmeter (Rhopoint Instruments, Troy, MI) over a 2x2mm area, at 0, 45, and 90 degrees. Knoop microhardness was measured on a Wilson VH1202 Micro Hardness Tester (0.025N load, 15 sec. dwell time, 6 indentations/disc). Data were compared using ANOVA and post-hoc Tukey (α=0.05).
Results: In general, composites with BAG65 were harder than those with BAG85. Monomer ratio had no effect on hardness. Empress was significantly harder than the experimental composites. For gloss, large particle composites had significantly lower gloss, and hybrid and small particle composites of 3:1 had the highest, along with Empress (See Table).
Conclusions: BAG-containing hybrid composites may provide sufficient hardness and polishability to be used clinically.