致龋菌、唾液缓冲能力与婴幼儿龋的相关性研究

目的探讨唾液中变形链球菌、乳酸杆菌和唾液pH值、缓冲能力与婴幼儿龋的关系。方法将178名42～54个月的儿童分为患龋组（患龋牙数≥5）87例和无龋组91人。吐唾法采集非刺激性唾液和嚼蜡法采集刺激性唾液各2ml，用选择性培养的方法检测刺激性唾液中变形链球菌、乳酸杆菌的检出率和计数水平；测定非刺激性及刺激性唾液的pH值和缓冲能力。结果患龋组唾液变形链球菌和乳酸杆菌的检出率分别为96．6％和79．3％，显著高于无龋组的63．7％和27．5％（P〈0．05）；患龋组两种细菌的计数水平比无龋组高近10倍。患龋组和无龋组刺激性唾液的初始pH值和对酸的缓冲能力均显著高于非刺激性唾液（P〈0．001）；患龋组刺激性和非刺激性唾液的初始pH值和缓冲能力均显著低于无龋组（P〈0．05）；无龋组中变形链球菌、乳酸杆菌和唾液pH值、缓冲能力之间无明显的相关性；患龋组刺激性唾液的缓冲能力与变形链球菌的计数水平显著相关（r=0．249，P〈0．05）。结论变形链球菌和乳酸杆菌是婴幼儿龋的重要致病菌；唾液的初始pH值和缓冲能力偏低可能是影响婴幼儿龋的重要因素。

Relationship between cariogenic microbe, salivary buffer capacity and early childhood caries

OBJECTIVE: To investigate the relationship between Mutans streptococcus (MS), Lactobacilli (LB), pH value and buffer capacity of saliva and early childhood caries (ECC). METHODS: A total of 178 children aged from 42 to 54 months were recruited from 14 urban kindergartens in Beijing. The ECC group contained 87 children with more than 5 decayed teeth, and the control group was composed of 91 caries-free children. Unstimulated (UWS, 2 ml) and stimulated (SWS, 2 ml) whole saliva were collected in each subject. The pH value and buffer capacity of saliva were measured using an electro-acidimeter (+/- 0.01pH). RESULTS: MS and LB were isolated from 96.6% and 79.3% of children with ECC, which were significantly higher than those (63.7%, 27.5%) of caries-free children (P < 0.05) respectively. The counts of MS and LB in children with ECC were approximately 10 times higher than that in caries-free children. Initial pH value and buffer capacity of SWS were significantly higher than that of UWS (P < 0.001) in both groups. The pH value and buffer capacity of both UWS and SWS in ECC children were significantly higher than caries-free children (P < 0.05). There were no significant correlations between MS, LB and pH value and buffer capacity of saliva in caries-free children. Significant correlation (r = 0.249, P < 0.05) was found between the numbers of MS and buffer capacity of stimulated saliva in ECC children. CONCLUSIONS: MS and LB were important pathogens for ECC. Lower initial pH value and buffer capacity of saliva may be an important factor of ECC.