Ghasempour Maryam, Rajabnia Ramazan, Irannejad Azin, Hamzeh Mahtab, Ferdosi Elahe, Bagheri Meghdad
Department of Pediatric Dentistry, Babol University of Medical Sciences, Babol, Iran.
Dent Res J (Isfahan). 2013 Jul;10(4):440-5.
One of the causative factors in development of dental caries is microorganisms. Two species of Mutans streptococci including Streptococcus mutans and Streptococcus sobrinus are associated with dental caries in human beings. The aim of this study was to investigate the frequency of S. mutans and S. sobrinus in saliva of children with different caries activity and ability to form biofilm and acid susceptibility of these microorganisms.
This analytical case-control study was performed on 83 preschool children, 4-6 years old. Children were divided into two groups including 41 caries-active and 42 caries-free children. Non-stimulated saliva samples were collected and culture and polymerase chain reaction techniques were used. Statistical analysis was performed using t-test, Chi-square, ANOVA, and Kappa tests.
S. mutans and S. sobrinus were found in 65% and 21.6% of the samples respectively. S. mutans was isolated from 75.6% of caries-active and 54.8% of caries-free children. Figures for S. sobrinus were 29.2% and 14.3% respectively. Acid susceptibility of microorganisms isolated from saliva was 87.43 in caries-active children and 94.30 for caries-free children. Biofilm formation of microorganisms in caries-active and caries-free children was 0.77 and 0.73, respectively.
Frequency of S. mutans in caries-active children was significantly higher than caries-free children, but the difference in frequency of S. sobrinus was not significant. Acid susceptibility of microorganisms in caries-active children was significantly lower, but the ability to form biofilm was not significantly different in two groups.
龋齿发展的致病因素之一是微生物。变形链球菌属的两种细菌，即变形链球菌和远缘链球菌，与人类龋齿有关。本研究的目的是调查不同龋齿活动度的儿童唾液中变形链球菌和远缘链球菌的频率，以及这些微生物形成生物膜的能力和酸敏感性。
本分析性病例对照研究对83名4 - 6岁的学龄前儿童进行。儿童被分为两组，包括41名患龋活跃儿童和42名无龋儿童。收集非刺激性唾液样本，并使用培养和聚合酶链反应技术。采用t检验、卡方检验、方差分析和kappa检验进行统计分析。
分别在65%和21.6%的样本中发现了变形链球菌和远缘链球菌。在75.6%的患龋活跃儿童和54.8%的无龋儿童中分离出了变形链球菌。远缘链球菌的相应数字分别为29.2%和14.3%。从患龋活跃儿童唾液中分离出的微生物的酸敏感性为87.43，无龋儿童为94.30。患龋活跃儿童和无龋儿童中微生物的生物膜形成分别为0.77和0.73。
患龋活跃儿童中变形链球菌的频率显著高于无龋儿童，但远缘链球菌频率的差异不显著。患龋活跃儿童中微生物的酸敏感性显著较低，但两组中形成生物膜的能力没有显著差异。
