title: Multilevel analysis of bacterial counts from chronic periodontitis after root planing/scaling, surgery, and systemic and local antibiotics: 2-year results.
abstract: OBJECTIVE
  To follow changes (over 2 years) in subgingival bacterial counts of five microbial complexes including health-related Actinomyces spp. in deeper pockets (≥5 mm) after periodontal treatments.
  
  
  METHODS
  EIGHT DIFFERENT TREATMENTS WERE STUDIED: (1) scaling+root planing (SRP); (2) periodontal surgery (SURG)+systemic amoxicillin (AMOX)+systemic metronidazole (MET); (3) SURG+locally delivered tetracycline (TET); (4) SURG; (5) AMOX+MET+TET; (6) AMOX+MET; (7) TET; and (8) SURG+AMOX+MET+TET. Antibiotics were given immediately following SRP. Subgingival plaque was collected mesiobuccally from each tooth, except third molars, from 176 subjects, completing the study, at baseline, 3, 6, 12, 18, and 24 months post-treatment and analysed for 40 different bacteria using checkerboard hybridization. A negative binomial (NB) generalized estimating equation (NB GEE) model was used to analyze count data and a logistic GEE was used for proportions.
  
  
  RESULTS
  We observed short-term beneficial changes in the composition of the red complex of up to 3 months by treating subjects with AMOX+MET+TET. Similar short-term improvements with the same treatment were observed for Tannerella forsythia and Treponema denticola of the red complex. SURG had also short-term beneficial effect on Porphyromonas gingivalis. No periodontal treatments applied to severely affected sites promoted the growth of Actinomyces. Smoking elevated counts of both the red and orange complex while bleeding on probing (BOP) and gingival redness were also predictors of more red complex counts. Comparatively similar findings were obtained by analyzing counts and by analyzing proportions.
  
  
  CONCLUSIONS
  Although short-term reductions in the counts of the red complex were observed in sites that were treated with AMOX+MET+TET, long-term significant effects were not observed with any of the eight treatments. Poor oral hygiene in patients with severe chronic periodontitis diminished the beneficial effects of treatment.
authors.affiliation: Faculty of Dentistry, Department of Oral Biology, University of Oslo, Oslo, Norway.
authors.forename: Ibrahimu
authors.initials: I
authors.lastname: Mdala
authors.forename: Ingar
authors.initials: I
authors.lastname: Olsen
authors.forename: Anne D
authors.initials: AD
authors.lastname: Haffajee
authors.forename: Sigmund S
authors.initials: SS
authors.lastname: Socransky
authors.forename: Birgitte Freiesleben
authors.initials: BF
authors.lastname: de Blasio
authors.forename: Magne
authors.initials: M
authors.lastname: Thoresen
keywords: NB GEE; antibiotics; chronic periodontitis; fractional response methods; microbiota; multilevel analysis; periodontal therapy