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Background Recent preventive strategies for dental caries focus on targeting the mechanisms underlying biofilm formation, including inhibiting bacterial adhesion. A promising approach to prevent bacterial adhesion is to modify the composition of acquired salivary pellicle. This in vitro study investigated the effect and possible underlying mechanism of pellicle modification by casein phosphopeptide (CPP) on Streptococcus mutans (S. mutans) initial adhesion, and the impact of fluoride on the efficacy of CPP.Methods The salivary pellicle-coated hydroxyapatite (s-HA) disc was modified by 2.5% CPP or 2.5% CPP supplemented with 900 ppm fluoride solutions. After cultivation of S. mutans, the adherent bacteria were visualized by scanning electron microscopy (SEM) and quantitatively evaluated using the plate count method. Confocal laser scanning microscopy (CLSM) was used to evaluate the proportions of total and dead S. mutans. The concentrations of total, free, and bound calcium and fluoride in CPP and fluoride-doped CPP solutions were determined. The water contact angle and zeta potential of s-HA with and without modification were measured. The data were statistically analyzed using one-way ANOVA followed by a Turkey post hoc multiple comparison test.Results Initial adhesion of S. mutans to s-HA was inhibited in response to pellicle modification by CPP and fluoride-doped CPP, and the latter was more efficient. CLSM analysis showed that the proportion of dead S. mutans did not differ between the groups. Water contact angle and zeta potential decreased after pellicle modification, and both were lowest in the fluoride-doped CPP group.Conclusions Pellicle modification by CPP inhibited S. mutans initial adhesion to s-HA, possibly by reducing hydrophobicity and negative charge on the s-HA surface, and incorporating fluoride into CPP enhanced its anti-adhesion effect. |
