A New Bioactive Glass inhibits Growth of Cariogenic Bacteria

Abstract

Objectives: To investigate the antibacterial effect of a new bioactive glass on cariogenic bacteria. Methods: The test material was a newly developed bioactive glass named Huaxi bioactive glass-ceramic (HX-BGC) and its antibacterial effect was compared with that of Bioactive glass 45S5 (BAG-45S5) and deionized water (negative control). The initial concentration of the HX-BGC and BAG-45S5 suspension was 250mg/ml. The MIC was determined by a microdilution method and growth test of S. mutans in agar plate was used to determine the MBC. After determining the MBC, four species of cariogenic bacteria (S. mutans, S. sobrinus, L. acidophilius, L. rhamnosus) were put into different tubes of BHI broth, some with HX-BGC added at different concentrations, some with BAG-45S5 added at half of the MBC and some with nothing added, for assessment of bacterial growth and acid production. The bacterial suspensions were cultured anaerobically at 37°C. Measurements of optical density (at 660nm) by a microplate reader and the pH of the supernatant were carried out at 6, 12, 24, and 48h. Results: Due to the turbidity induced by precipitation of HX-BGC and BAG-45S5 in the suspension, determination of their MIC was not possible. The MBC of HX-BGC and BAG-45S5 were 15.6mg/ml and 31.25mg/ml, respectively. The mean optical density value of the HX-BGC and BAG-45S5 suspensions did not change during the 48 hours of culturing while that of the BHI suspension increased from 0 to 0.594. The mean pH value of the BHI suspensions dropped from 7.18 to 3.86 but those of HX-BGC and BAG-45S5 suspensions kept steady at around 9 and around 10, respectively. Conclusions: The study HX-BGC can inhibit acid production and growth of cariogenic bacteria.