title: Periodontal health and relative quantity of subgingival Porphyromonas gingivalis during orthodontic treatment.
abstract: OBJECTIVE
  To examine periodontal changes and the relative quantity of subgingival Porphyromonas gingivalis during orthodontic treatment.
  
  
  METHODS
  The study subjects were recruited consecutively among malocclusion patients seeking orthodontic treatment. Group A comprised 28 subjects (17.6 ± 5.68 years of age) at the beginning of orthodontic treatment, and group B comprised 20 subjects (17.8 ± 4.49 years of age) at the end of orthodontic treatment. Plaque index (Pl.I), gingival index (GI), and probing pocket depth (PPD) were measured before and after appliance placement in group A and before and after appliance removal in group B. Real-time quantitative polymerase chain reaction was used to quantify P. gingivalis in subgingival plaque at each time point.
  
  
  RESULTS
  There was a significant increase in Pl.I and GI during the first 3 months of appliance placement but a significant decrease in Pl.I, GI, and PPD during the first 6 months after appliance removal. The carriage and relative quantity of subgingival P. gingivalis were high at the end of orthodontic treatment, and they decreased significantly after appliance removal. The amount of subgingival P. gingivalis after appliance removal (for a period of 6 months) was higher than the amount measured before appliance placement.
  
  
  CONCLUSIONS
  Fixed orthodontic treatment is conducive to dental plaque accumulation and gingival inflammation. In our study, after removal of orthodontic appliances, periodontal health improved, and the carriage and amount of subgingival P. gingivalis decreased. Nevertheless, the amount of subgingival P. gingivalis remained high for 6 months after appliance removal, and this finding might imply a potential risk to periodontal health in certain patients.
authors.affiliation: Orthodontics Section, First Affiliated Hospital of Dalian Medical University, Dalian, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Liu
authors.forename: Jinglu
authors.initials: J
authors.lastname: Sun
authors.forename: Yilei
authors.initials: Y
authors.lastname: Dong
authors.forename: Hui
authors.initials: H
authors.lastname: Lu
authors.forename: Humin
authors.initials: H
authors.lastname: Zhou
authors.forename: B Frode
authors.initials: BF
authors.lastname: Hansen
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Song
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D058491:Bacterial Load; D002648:Child; D004269:DNA, Bacterial / Q000032:analysis; D003773:Dental Plaque / Q000382:microbiology*; D005260:Female; D005891:Gingivitis / Q000209:etiology*; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000628:therapy; D016910:Orthodontic Brackets / Q000009:adverse effects*; D016133:Polymerase Chain Reaction / Q000379:methods; D016966:Porphyromonas gingivalis / Q000302:isolation & purification; D018709:Statistics, Nonparametric; D014087:Tooth Movement Techniques; D055815:Young Adult
chemical_list: D004269:DNA, Bacterial