title: Differential benefits of amoxicillin-metronidazole in different phases of periodontal therapy in a randomized controlled crossover clinical trial.
abstract: BACKGROUND
  The specific advantage of administering systemic antibiotics during initial, non-surgical therapy or in the context of periodontal surgery is unclear. This study assesses the differential outcomes of periodontal therapy supplemented with amoxicillin-metronidazole during either the non-surgical or the surgical treatment phase.
  
  
  METHODS
  This is a single-center, randomized placebo-controlled crossover clinical trial with a 1-year follow-up. Eighty participants with Aggregatibacter actinomycetemcomitans-associated moderate to advanced periodontitis were randomized into two treatment groups: group A, antibiotics (500 mg metronidazole plus 375 mg amoxicillin three times per day for 7 days) during the first, non-surgical phase of periodontal therapy (T1) and placebo during the second, surgical phase (T2); and group B, placebo during T1 and antibiotics during T2. The number of sites with probing depth (PD) >4 mm and bleeding on probing (BOP) per patient was the primary outcome.
  
  
  RESULTS
  A total of 11,212 sites were clinically monitored on 1,870 teeth. T1 with antibiotics decreased the number of sites with PD >4 mm and BOP per patient significantly more than without (group A: from 34.5 to 5.7, 84%; group B: from 28.7 to 8.7, 70%; P <0.01). Twenty patients treated with antibiotics, but only eight treated with placebo, achieved a 10-fold reduction of diseased sites (P = 0.007). Consequently, fewer patients of group A needed additional therapy, the mean number of surgical interventions was lower, and treatment time in T2 was shorter. Six months after T2, the mean number of residual pockets (group A: 2.8 ± 5.2; group B: 2.2 ± 5.0) was not significantly different and was sustained over 12 months in both groups.
  
  
  CONCLUSIONS
  Giving the antibiotics during T1 or T2 yielded similar long-term outcomes, but antibiotics in T1 resolved the disease quicker and thus reduced the need for additional surgical intervention.
authors.affiliation: Department of Periodontology, University of Geneva, Geneva, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mombelli
authors.forename: Adnan
authors.initials: A
authors.lastname: Almaghlouth
authors.forename: Norbert
authors.initials: N
authors.lastname: Cionca
authors.forename: Delphine S
authors.initials: DS
authors.lastname: Courvoisier
authors.forename: Catherine
authors.initials: C
authors.lastname: Giannopoulou
mesh_terms: D000328:Adult; D000368:Aged; D016976:Aggregatibacter actinomycetemcomitans / Q000187:drug effects; D000658:Amoxicillin / Q000008:administration & dosage / Q000627:therapeutic use*; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000008:administration & dosage / Q000627:therapeutic use*; D008875:Middle Aged; D016871:Pasteurellaceae Infections / Q000601:surgery / Q000628:therapy; D057747:Periodontal Debridement / Q000379:methods; D010512:Periodontal Index; D010514:Periodontal Pocket / Q000601:surgery / Q000628:therapy; D010518:Periodontitis / Q000382:microbiology / Q000601:surgery / Q000628:therapy*; D010919:Placebos; D013524:Surgical Flaps / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D010919:Placebos; D008795:Metronidazole; D000658:Amoxicillin
keywords: Amoxicillin; case management; metronidazole; periodontitis; randomized controlled trial.