Objective To study the inhibitory effect of erythritol by contrast to xylitol on the adherence of Streptococcus mutans（S.mutans）. Methods S.mutans were incubated respectively in mass fraction of 2%, 4%, 6%, 8% erythritol or xylitol culture medium and the negative control group in TPY liquid medium tubes under anaerobic conditions for 24 hours. Wash the tubes in which there were S.mutans biofilms with phosphate buffer solution （PBS） for 3 times. Add PBS into the tubes, then put them on ultrasonic oscillator. Collect stock solutions in the tubes and dilute them in the ratio of 10%, then take 50 μL and anaerobic culture on TPY solid medium for 48 hours. Compare the inhibitory effect of erythritol and xylitol through colony-forming unit（CFU） value which was got by colony counting method. The S.mutans CFU value curves of erythritol, xylitol and negative control group were made. Results The CFU values of erythritol group and xylitol group were significantly lower than that of the negative control group. The CFU values gradually decreased while the mass fraction of erythritol and xylitol increased. The two results mentioned above both had statistical significance. The CFU values of xylitol group were lower than that of erythritol group in the same mass fraction of 2%, 4%, 6%, 8%. But the CFU values of erythritol group and xylitol group in mass fraction of 2% and 4% did not have significant difference. Conclusion Erythritol and xylitol have inhibitory effects on the adherence of S.mutans. And the effects enhance as mass fraction increase. The inhibitory effects of erythritol and xylitol have no significant difference in mass fraction of 2% and 4%, while the inhibitory effect of xylitol are better than that of erythritol in mass fraction of 6% and 8%.
