Methods: S. mutans biofilms were formed in 25 % THYE (Todd Hewitt Broth + 5 mg/mL yeast extract) with 30 mmol/L sucrose and varying concentrations of bisphenol A glycerolate dimethacrylate (BisGMA), triethyleneglycol dimethacrylate (TEGDMA), camphorquinone (CQ), or ethyl 4-N,N-dimethylaminobenzoate (4E). Controls were grown without additives. At 4 h and 24 h, biofilms were evaluated for metabolic activity (MTT assay-3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), overall biomass (crystal violet), and growth medium pH. Three experiments (each with n=4) were performed. Viability analysis was performed on select samples using laser scanning confocal microscopy. One-way analysis of variance was applied with Tukey-Kramer multiple comparisons (P<0.05 indicates significance).
Results: TEGDMA (500 µg/mL) significantly reduced metabolic activity but not biomass at 24 h. BisGMA (50 µg/mL) significantly reduced biofilm metabolic activity and biomass at 24 h. CQ (100 µg/mL) had the opposite effect, with significantly reduced metabolic activity and biomass at 4 h followed by significantly higher metabolic activity at 24 h, suggesting a delay in biofilm growth. 4E (up to 10 µg/mL) had no detectable effect. Viability staining at 24 h supported these results, with an increase in membrane-compromised cells with 50 µg/mL BisGMA and an increase in live cells for 100 µg/mL CQ.
Conclusions: Monomers and photoinitiators that can leach from dental polymeric materials can alter oral biofilm growth. These material-directed changes in biofilm activity may play an important role in the formation of pathogenic oral biofilms and the development of recurrent caries.
Acknowledgements: Interagency Agreement between the National Institute of Dental and Craniofacial Research and NIST [Y1-DE-7005-01].
Keywords: Bacterial, Biofilm, Caries organisms, Dental materials and Polymers
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