【Objective】 To determine the effect of sucrose concentration on cariogenicity of Streptococcus mutans in dental plaque of S-ECC. 【Methods】 Plaque samples were collected from 67 children aged from 3 to 5. Strains of Streptococcus mutans were identified

purified and then cultured in PYG medium with 1%

5%

10%

and 20% sucrose. The pH value of supernatant was measured to evaluate acidogencity of Streptococcus mutans

and OD600 to evaluate the propagating status. The quantities of water insoluble glucans (WIG) were measured by anthrone method. Turbidimetry was used to measure the adhesive ability. 【Results】 Acidogenicity

propagation

WIG synthesis

and adhesion ratio of Streptococcus mutans from S-ECC group were statistically higher than caries free group. The cariogenicity of Streptococcus mutans enhanced with the increase of sucrose concentration. In 5% sucrose group

pH decreased to critical pH5.5. Propagation

WIG synthesis and adhesion ratio increased a lot

especially in S-ECC group. When sucrose concentration was above 5%

?驻pH

OD600

WIG and adhesion ratio still increased

however

the growth rate became slow down. 【Conclusion】 The cariogenicity of Streptococcus mutans was dose-dependent with sucrose levels

and the concentration of which exceeded 5% is considered to be more cariogenic and important for S-ECC prevention.