乳酸链球菌对大鼠人工龋发生的影响

目的研究益生菌乳酸链球菌（L.lactis）对大鼠窝沟龋发生的影响。 方法选取出生21 d SD大鼠20只，按照随机数字表法随机均分为对照组、L.lactis组（Ll组）、血链球菌（S.sanguis）+变异链球菌（S.mutans）+内氏放线菌（A.naeslundii）组（SSA组）及S.sanguis + L.lactis + S.mutans + A.naeslundii组（SLSA组），每组5只大鼠。大鼠口腔内接种相应菌液并喂食致龋饲料2000#，连续喂养6周，Keyes计分法将龋病进展划分为釉质层（E）、牙本质浅层（Ds）、牙本质中层（Dm）和牙本质深层（Dx）4个级别，对4组各60颗大鼠磨牙窝沟龋进行记分，评价L.lactis对人工诱导大鼠窝沟龋发生的影响，同时每周记录大鼠体质量1次。数据以单因素方差分析（One-Way ANOVA）及LSD-t检验进行统计分析。 结果对照组窝沟龋E级、Ds级、Dm级Keyes计分均值（45.20 ± 3.35）、（41.40 ± 2.41）、（14.80 ± 4.32）]高于Ll组对应级别均值（37.60 ± 6.27）、（30.00 ± 7.62）、（3.80 ± 4.38）]，差异有统计学意义（E级：t= 2.739，P= 0.010；Ds级：t= 4.108，P<0.001；Dm级：t= 3.964，P<0.001）。SSA组E级、Ds级、Dm级Keyes计分结果均值分别为（46.60 ± 1.62）、（44.80 ± 2.14）、（12.80 ± 2.79），高于SLSA组对应级别均值（38.60 ± 5.50）、（31.40 ± 5.27）、（5.20 ± 2.17）]，差异有统计学意义（E级：t= 4.944，P<0.001，Ds级：t= 6.606，P<0.001，Dm级：t= 3.747，P= 0.001）。对照组体质量增加值（156 ± 14）g]与Ll组体质量增加值（161 ± 25）g]比较，差异无统计学意义（t= 0.410，P= 0.687）；SSA组体质量增加值（158 ± 24）g]与SLSA组体质量增加值（152 ± 25）g]比较，差异无统计学意义（t= 0.410，P= 0.687）。 结论益生菌L.lactis可能对大鼠人工龋病发生有一定的防治作用。

The inhibitory effects of Lactococcus lactis on caries development in rats

ObjectiveTo investigate the effect of Lactococcus lactis (L.lactis) on fissure caries. MethodTwenty SD rats of 21-day-old were randomly divided into 4 groups by the random number table, and 5 rats in each group: Control group (no caries) , L.lactis (Ll) (inoculating L.lactis) , Streptococcus sanguis + Streptococcus mutans + Actinomyces naeslundii (SSA group) (inoculating Streptococcus sanguis, Streptococcus mutans and Actinomyces naeslundii) and Streptococcus sanguis + L.lactis + Streptococcus mutans + Actinomyces naeslundii (SLSA group) (inoculating Streptococcus sanguis, L.lactis, Streptococcus mutans and Actinomyces naeslundii) . All SD rats were fed with cariogenic forage 2000# mixed with the above four group of bacteria. After 6 weeks, the fissure caries and their severity (E, Enamel caries; Ds, slight dentinal caries; Dm, moderate dentinal caries; Dx, extensive dentinal caries) were checked according to Keyes′ system, and further evaluate the effects of L.lactis on dental caries development in SD rats. Each group has 60 teeth. The weight of the rats was measured everyweek. The data were analyzed by One-Way ANOVA and LSD-t test. ResultsThe mean value of E, Ds and Dm levels of control group were 45.20 ± 3.35, 41.40 ± 2.41 and 14.80 ± 4.32, and the mean value of E, Ds and Dm levels of Ll was 37.60 ± 6.27, 30.00 ± 7.62 and 3.80 ± 4.38. The control group was significantly higher than Ll group (E: t= 2.739, P= 0.010; Ds: t= 4.108, P<0.001; Dm: t= 3.964, P<0.001) . At E, Ds and Dm levels, the mean value of SSA group (46.60 ± 1.62) , (44.80 ± 2.14) , (12.80 ± 2.79) ] was higher than SLSA group (38.60 ± 5.50) , (31.40 ± 5.27) , (5.20 ± 2.17) ] (E: t = 4.944, P<0.001; Ds: t = 6.606, P<0.001; Dm: t = 3.747, P = 0.001) . The gaining weight (g) of control and Ll group were (156 ± 14) and (161 ± 25) separately, and both did not show statistical difference (t= 0.410, P= 0.687) . The gaining weight (g) of SSA and SLSA were (158 ± 24) and (152 ± 25) separately, and both did not show statistical difference (t= 0.410, P= 0.687) . ConclusionL.lactis mayprevent the development of dental caries in SD rats.