title: [Comparison of periodontal indices and Porphyromonas gingivalis between conventional and self-ligating brackets].
abstract: OBJECTIVE
  To compare the periodontal indices and Porphyromonas gingivalis (P. gingivalis) between the use of self-ligating brackets and conventional brackets.
  
  
  METHODS
  Thirty patients were divided into 2 groups(n=15). Self-ligating brackets were used in the experimental group. Conventional brackets were used in the control group. Clinical periodontal indices, including plaque index (PLI), gingival index (GI) and probing depth (PD) of observed teeth were examined at three different time points: Before orthodontic treatment, the first month after treatment and the third month after treatment. Subgingival plaques were collected simultaneously at each time point. The number of total bacteria and P. gingivalis in each sample were detectd and quantitated by real-time quantitative polymerase chain reaction, the percentage of P. gingivalis in total bacteria was obtained.
  
  
  RESULTS
  Before treatment, the periodontal indices and the percentage of P. gingivalis in total bacteria had no difference between the two groups (P>0.05). After 1 and 3 months respectively, the periodontal indices and the percentage of P. gingivalis in total bacteria increased with time (P<0.05) and were obviously lower than those of the control group (P<0.05).
  
  
  CONCLUSIONS
  Compared with conventional brackets, the self-ligating brackets are better for periodontal health. But it is adverse effect on oral health.
authors.affiliation: Dept.of Orthodontics, General Hospital of Daqing Oil Field, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Shi
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Liu
authors.forename: Jingqiu
authors.initials: J
authors.lastname: Hou
authors.forename: Zhengbin
authors.initials: Z
authors.lastname: Yan
authors.forename: Hui
authors.initials: H
authors.lastname: Peng
authors.forename: Xing
authors.initials: X
authors.lastname: Chang
mesh_terms: D003773:Dental Plaque; D003774:Dental Plaque Index; D006801:Humans; D010512:Periodontal Index; D016966:Porphyromonas gingivalis