title: Microbiologic Observations After Four Treatment Strategies Among Patients With Periodontitis Maintaining a High Standard of Oral Hygiene: Secondary Analysis of a Randomized Controlled Clinical Trial.
abstract: BACKGROUND
  The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP), with or without adjunctive metronidazole, when treating chronic destructive periodontitis remains equivocal, as does the long-term association between clinical and microbiologic outcomes after such strategies. The aim of this study is to examine the relationship between clinical and microbiologic outcomes of four different treatment strategies for chronic destructive periodontitis among patients who maintain excellent oral hygiene and low gingival bleeding scores.
  
  
  METHODS
  One hundred eighty-four patients with periodontitis and capable of maintaining a high standard of oral hygiene were randomly allocated to one of four treatment groups: 1) FDIS + metronidazole; 2) FDIS + placebo; 3) SRP + metronidazole; and 4) SRP + placebo. Recordings of plaque, bleeding on probing, probing depth (PD), and clinical attachment level were carried out in four sites per tooth at baseline, 3 and 12 months after treatment. Before treatment, pooled subgingival samples were obtained from the five deepest pockets, which were sampled again 3 and 12 months after treatment. Microbiologic assessments of eight putative periodontal pathogens were performed using the checkerboard DNA-DNA hybridization method.
  
  
  RESULTS
  Levels of bacterial species were already relatively low at baseline. The only microbial factor statistically significantly associated with the clinical outcomes of treatment after 12 months was the association between reductions of Tannerella forsythia and being free from PD ≥5 mm.
  
  
  CONCLUSIONS
  In this clinical trial, the only microbial factor associated with the clinical outcomes after 12 months was a statistically significant association between the reductions of T. forsythia and being free from PD ≥5 mm.
authors.affiliation: Department of Periodontology, Institute of Clinical Odontology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
authors.forename: Hans R
authors.initials: HR
authors.lastname: Preus
authors.affiliation: Department of Oral Microbiology and Immunology, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Dahlen
authors.affiliation: Department of Periodontology, Institute of Clinical Odontology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
authors.forename: Per
authors.initials: P
authors.lastname: Gjermo
authors.affiliation: Department of Dentistry, Health, Aarhus University, Aarhus, Denmark.
authors.forename: Vibeke
authors.initials: V
authors.lastname: Baelum
mesh_terms: D000328:Adult; D000368:Aged; D000890:Anti-Infective Agents / Q000627:therapeutic use; D000891:Anti-Infective Agents, Local / Q000627:therapeutic use; D058491:Bacterial Load / Q000187:drug effects; D002710:Chlorhexidine / Q000627:therapeutic use; D055113:Chronic Periodontitis / Q000382:microbiology* / Q000628:therapy; D003131:Combined Modality Therapy; D003774:Dental Plaque Index; D012534:Dental Scaling / Q000379:methods; D004203:Disinfection / Q000379:methods; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000627:therapeutic use; D008875:Middle Aged; D009910:Oral Hygiene; D017622:Periodontal Attachment Loss / Q000382:microbiology / Q000628:therapy; D010512:Periodontal Index; D010514:Periodontal Pocket / Q000382:microbiology / Q000628:therapy; D010919:Placebos; D016745:Root Planing / Q000379:methods; D000070436:Tannerella forsythia / Q000187:drug effects / Q000302:isolation & purification; D016896:Treatment Outcome
chemical_list: D000890:Anti-Infective Agents; D000891:Anti-Infective Agents, Local; D010919:Placebos; D008795:Metronidazole; D002710:Chlorhexidine
keywords: Alveolar bone loss; anti-bacterial agents; dental scaling; oral hygiene; periodontal attachment loss; root planing