目的:对老年人牙菌斑进行群落分析,以了解根面龋微生境构成的多样性。方法:提取25例不同龋敏感性老年人牙菌斑细菌DNA,使用PCR-DGGE技术分析细菌遗传多样性。采用SPSS12.0软件包对不同组间细菌基因型数量做方差分析。结果:分布于根龋组牙菌斑内的细菌基因型比另外2组显著增多。冠龋组与无龋组间无显著性差异。结论:老年人根龋患者牙菌斑细菌群落多样性明显高于冠龋患者及无龋者。 Objective: To analyze the dental plaque in the elderly to understand the diversity of root caries micro-habitat. Methods: Bacterial DNA from 25 cases of dental caries in different caries-sensitive elderly was extracted and the bacterial genetic diversity was analyzed by PCR-DGGE. The number of bacterial genotypes in different groups was analyzed by ANOVA using SPSS12.0 software package. Results: The genotypes of bacteria distributed in the root caries group were significantly higher than the other two groups. No significant difference between crown caries group and caries-free group. Conclusion: The bacterial community diversity of dental caries in elderly patients with root caries is significantly higher than those in caries-bearing patients and caries-free subjects.