Streptococcus mutans Biofilm formation dental enamel Vs Hidroxiapatite disc

Method:

Streptococcus mutans was cultured on BHI 159 AU (Brain Heart Infusion) and Lactobacillus acidophilus in infusion CO14919 MRS. Artificial saliva was prepared to mount the experiment. An inoculum of S. mutans was used as Treatment 1; S. mutans and L. acidophilus 1:1 for Treatment 2; and finally L. acidohilus for treatment 3 within 6-well sterile culture plates with stirring and incubation at 37°C for 6 and 24 Hrs. These plates contained the hydroxyapatite disks and 2 mm slices of natural tooth enamel to create a model of oral cavity conditions. All experiments were done in triplicate. After incubation, samples were centrifuged at 1200 rpm to determine biofilm; samples were observed by stereomicroscope and cells were stained with DAPI.

Result: S. mutans formed a biofilm at 6 and 24 hours only on the enamel surface and not on hydroxyapatite (Treatment 1). It could be seen that both at 6 and 24 hrs, biofilm formation was better on the enamel surfaces in the presence of L. acidophilus (Treatment 2). L. acidophilus did not form a biofilm in any of the two surfaces at either of the two times (Treatment 3).

Conclusion: S. mutans formed biofilm on the enamel surface and not  on hydroxyapatite. Biofilm formation was significantly better in the presence of L. acidopilus. L. acidophilus was not able to form biofilm on any of the two surfaces. S. mutans, in the presence of L. acidophilus, improves its adherence.