菌斑固相、变形链球菌及葡聚糖对酸的缓冲作用

目的研究糖代谢后菌斑固相缓冲力的变化及影响因素。方法采集40名18~21岁的大学生的饥饿牙菌斑,体外10%蔗糖孵育1h。体外制备无糖培养和2%蔗糖培养的变链菌团。以25mmol/L KCl制备菌斑固相、变链菌团和不溶性葡聚糖混悬液及可溶性葡聚糖溶液,用1mmol/LHCl滴定并计数细菌密度,统计学分析。结果变链菌团代谢蔗糖后的缓冲容量为(0·099±0·047)mmol/L,比无蔗糖培养的变链菌团的缓冲容量(0·609±0·202)mmol/L低,且缓冲力随细菌密度降低直线下降,葡聚糖几乎没有缓冲作用[(0·028~0·032)mmol/L]。人牙菌斑固相缓冲力的变化规律与体外纯菌培养研究结果一致。结论菌斑固相缓冲力与所含细菌密度密切相关。

Buffering effects of plaque solid, Streptococcus mutans and glucans

OBJECTIVE: To investigate the buffer capacity of insoluble plaque mass including bacteria and glucans matrix. METHODS: Plaque samples (starved or incubated 1 h with 10% sucrose), Streptococcus mutans (S. mutans) mass, and insoluble/soluble glucans were titrated with 1 mmol/L HCl. Meanwhile, the density of bacteria was counted and related to buffer capacity. RESULTS: The bacteria density had significant effects on acid buffer capacity in dental plaque, but the effect reduced with consuming sugar. S. mutans mass with no sucrose incubating contributed to the buffer capacity of (0.609 +/- 0.202) mmol/L, and S. mutans mass with 2% sucrose had only the buffer capacity of (0.099 +/- 0.047) mmol/L. In the mean time, glucans had no effect on acid buffering (0.028 - 0.032 mmol/L). CONCLUSIONS: The bacteria including S. mutans may be the main contributor to acid buffering in plaque solid.