Effects of Bovine Lactoferrin on Acid Fermentation and Enamel Demineralization

Objectives: The purposes of this study were to evaluate the effects of bovine lactoferrin, as an antimicrobial inhibitor, on acid fermentation and on enamel demineralization using Streptococcus mutans in culture system and in artificial mouth model system. Methods: In culture system, cell suspension of S. mutans MT8148, PBS (control) or lactoferrin solution, and heart infusion broth with sucrose were incubated at 37°C for 18 hours. There were 1% of the final concentrations of sucrose and lactoferrin in the tube. In artificial mouth model system, two identical artificial mouths were used. Each artificial mouth consisted of a vessel and a 9mm flat bulb pH electrode with an 18mm diameter Teflon holder. Four enamel slabs were seated on the Teflon holder. The pH electrode was set upside down in the center of the artificial mouth. PBS or lactoferrin solution, cell suspension of S. mutans MT8148, and heart infusion broth supplemented with sucrose were supplied separately and constantly for 18 hours. The final concentrations of sucrose and lactoferrin on the electrode were 1%, the same as the experiment in culture system. The following parameters were determined for evaluation, the amount of artificial biofilm, the changes in pH underneath the biofilm, the changes in enamel microhardness measured by a Vicker's hardness tester. Outcome was statistically analyzed by Student's t-test. Results: Bovine lactoferrin (1%) delayed the pH decrease in culture system and in artificial mouth model system. The artificial biofilm accumulation was not reduced by bovine lactoferrin in artificial mouth model system. The changes in microhardness on enamel slabs in bovine lactoferrin group (11.82±5.15) were significantly less hardness reduction than those in control group (47.2±8.18) (p < 0.001). Conclusion: The results of this study suggest that bovine lactoferrin might have inhibitory effects against acid fermentation and demineralization of enamel by S. mutans.