Biofilm-Inhibitory Effect of Dental Composites Containing Gallium-Doped Bioactive Glass

Objectives: To characterize the antibacterial and biofilm-inhibition effects of the experimental dental composites containing gallium-doped bioactive glass (Ga-bioglass).
Methods: The Ga-bioglass (Na₂O-SiO₂-CaO-P₂O₅-Ga₂O₃) was synthesized using a sol-gel method, calcinated at about 700°C, ground using a planetary ball mill, and sieved to the fine powder (mean ~3.4 µm). SEM/EDS analysis showed the Ga-bioglass containing 15.5% Ga₂O₃. The control composite was formulated with 29% commercial dental monomers (BisGMA:EBPAGMA:HDDMA = 4:4:2), 1% photo initiator, and 70% commercial UltraFine F-releasing glass filler (SCHOTT AG, Germany). Experimental composites were formulated by replacing part of the filler contents with 10%, 20%, 25%, and 30% Ga-bioactive glass. To test the biofilm-inhibition effects, light-cured composites discs (10 mm diameter, 1.5 mm thick, n=4) were UV-sterilized and placed vertically in 3 mL culture medium inoculated with S. mutans. After 24-hour incubation at 37^oC with 5% CO₂, S. mutans biofilms were briefly sonicated; and serial dilutions of the suspension were plated and incubated for 36 hours. S. mutans biofilm formation in colony forming units (CFU) were recorded and further analyzed using ANOVA and Tukey test (a=0.05).
Results: As shown in Table 1, dental composites containing Ga-bioglass had significantly lower S. mutans biofilms than the control (p<0.05), which indicates significant biofilm-inhibitory effect of the Ga-bioglass.
Conclusions: Conclusion: The dental composites containing 10-25% Ga-bioglass all have significant inhibitory effects against S. mutans biofilms.