Method: S. mutans strains NUM-Smk 51, NUM-Smk 52 and NUM-Smk 89 (serotype k) were used. UA159 serotype cwas used as a control strain. Biofilm formation was established by crystal violet staining. The nicotine concentrations investigated in this study ranged between 0-32 mg/ml.
Result: All strains expressed significantly higher (p < 0.05) biofilm as the nicotine concentration increased up to 8 mg/ml. The NUM-Smk 51 strain exhibited the least biofilm formation among the three strains, and significantly less than the control UA159 strain up to 8 mg/ml in total growth (planktonic and biofilm formation) and 4 mg/ml in biofilm formation. Moreover, it was the most affected strain in the presence of nicotine with 73.35% and 121.78% increase in total growth and biofilm, respectively.
Conclusion: Overall, the growth and biofilm formation of the three S, mutans serotype k strains are affected by increased nicotine, while the NUM-Smk 51 strain was the most nicotine-sensitive strain. These results provide evidence on the effect of nicotine on an organism associated with AT and IE, both diseases strongly linked with smoking.