[Quantitative study of porphyromonas gingivalis in subgingival plaques of orthodontic adults]

To assess the early variation of clinical periodontal indexes and Porphyronwnas gingivulis (Pgingivalis) in subgingival plaques of orthodontic adults.

11 orthodontic adults were selected. Clinical periodontal indexes of observed teeth were examined at three different time points: Before orthodontic treatment, the first month after treatment and the third month after treatment, and subgingival plaques were collected simultaneously at each time point. Clinical periodontal indexes included four ones: Plaque index (PU), sulcus bleeding index (SBI), probing depth (PD), and attachment loss. We used real-time quantitative polymerase chain reaction to detect and quantitate the number of total bacteria and P.gingivalis in each sample to obtain positive rate of P.gingivalis and the percentage of P. gingiaalis in total bacteria.

PLI and SBI of the first and third month were more than that of the baseline (P < 0.05). PD rose at the first month after treatment (P < 0.05), and then dropped at the third month. PD of all the 11 participants was lower than 2 mm. No attachment loss was found. The positive rate of P.gingivolis was stable (45.5%) and the proportion of Pgingivalis had no significant difference (p > 0.05) at each time point.

Fixed orthodontic appliances caused plaque accumulation, accordingly slight gingiva inflammation and the increasement of P.gingivalis occurred in the early stage, hut none periodontitis was found.