Mechanical Properties of Antibacterial Dental Composites Containing Gallium-Doped Bioactive Glass

Objectives: To study the mechanical properties of antibacterial 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 and sieved to fine powder (mean ~3.4µm). SEM/EDS analysis showed that the Ga-bioglass contains 15.5% Ga₂O₃. The control composite was formulated with 29% commercial dental monomers (BisGMA:EBPAGMA:HDDMA = 4:4:2), 1% photoinitiators, and 70% commercial UltraFine F-releasing glass filler (SCHOTT AG, Germany). Experimental composites were formulated by replacing part of the filler contents in the control with 10%, 20%, 25%, and 30% Ga-bioglass. Additional 5% synthesized antimicrobial monomers C16DC2 or DD11, or 3% gallium-chelate monomer were added to the 20%Ga-bioglass composite (composition shown in Table 1). The composite specimens (2×2×25mm, n=12) were prepared by light-cure tested for flexural strength and flexural modulus on Instron 5566 after 24h storage in de-ionized water at 37^oC. The data were analyzed using ANOVA and Tukey’s HSD test (a=0.05).
Results: Table 1 shows the flexural strength and flexural modulus of experimental antibacterial dental composites.
Conclusions: The experimental composite containing up to 20% Ga-bioglass and 5% DD11 have similar mechanical properties to the control. Further increase of the amount of Ga-bioglass filler or adding 5% antimicrobial monomer C16DC2 or 3% Ga-chelate monomer will significantly decrease the mechanical properties.