Objective To investigate the distribution of rag genotypes of Porphyromonas gingivalis（P.gingivalis） in chronic periodontitis patients. Methods Subgingival plaque samples were collected from 50 chronic periodontitis patients. The occurrence of P.gingivalis was determined by polymerase chain reaction（PCR） using 16S rDNA-specific primers. Distribution of rag genotypes was assessed in P.gingivalis positive samples by PCR. Results The occurrence of P.gingivalis was 70.7%, and the distribution of four rag genotypes among P.gingivalis positive samples was as follows: rag-1 60.4%; rag-2 23.6%; rag-3 44.3%; rag-4 15.1%, respectively. Conclusion P.gingivalis with various rag genotypes was present in subgingival plaque samples from chronic periodontitis patients, and P.gingivalis with rag-1 and rag-3 were more predominant in chronic periodontitis patients, which may be associated with the development of periodontitis.
