title: Repeated metronidazole and amoxicillin treatment of periodontitis. A follow-up study.
abstract: BACKGROUND
  The prevailing concept is that little or no clear benefit is derived from antibiotic therapy in chronic periodontitis. Studies to determine the effect of metronidazole plus amoxicillin (M+A) on adult periodontitis are questionable because standard design for clinical trials was usually not used. In addition, there is no information about the effect of M+A as the sole therapy for periodontitis.
  
  
  METHODS
  A randomized, triple-blind, controlled clinical trial was used to determine the effect of systemic administration of M+A, as the sole therapy, in progressive adult periodontitis. Forty-six subjects with moderate to advanced adult periodontitis who showed > or =2 mm attachment loss in at least 2 sites in the previous 2 months were entered in the study. Subjects were randomly distributed to a group who received 21 tablets of metronidazole 250 mg plus amoxicillin 500 mg, or to a group receiving a placebo (1 tablet every 8 hours for 1 week). Patients were examined every 2 months for 12 months. The M+A or placebo regimen was repeated at 4 and 8 months. No effort was made to change the oral habits of patients and they received no additional therapy. Differences between groups were assessed using the Mann-Whitney U test. The differences at every 2-month interval within each group were assessed using the ANOVA test.
  
  
  RESULTS
  Seven subjects abandoned the study; at 12 months the M+A group had 20 subjects and the placebo group 19. There were no significant differences in the clinical parameters at baseline between the 2 groups. After 2 months and thereafter, the M+A group showed significant clinical improvement while the placebo group showed a progressive deterioration of periodontal status. At 12 months compared to baseline, subjects of the M+A group showed: 1) a significant overall mean attachment gain of 0.43 mm (P = 0.005); 2) a significant decrease of active sites (P< or =0.03); 3) a significant increase of sites gaining attachment level (P< or =0.01); 4) a significant reduction of pocket depth (P< or =0.00006); and 5) a significant decrease in percentage of bleeding on probing sites (BOP) (P< or =0.0005). Significant differences between both groups at all 2-month evaluations were found in overall mean attachment level (P < or =0.000004), in percent of active sites (P< or =0.03), and in percent of BOP sites (P< or =0.02). Sites exhibiting > or =2 mm of attachment loss in 2 successive or alternate evaluations, and periodontal abscess were noticed only in the placebo group.
  
  
  CONCLUSIONS
  A 1-week course of systemic M+A every 4 months, as the only therapy, arrests the progression of adult periodontitis and significantly improves the clinical parameters of the disease.
authors.affiliation: Department of Conservative Dentistry, Faculty of Dentistry, University of Chile, Santiago. nlopez@interactiva.cl
authors.forename: N J
authors.initials: NJ
authors.lastname: López
authors.forename: J A
authors.initials: JA
authors.lastname: Gamonal
authors.forename: B
authors.initials: B
authors.lastname: Martinez
mesh_terms: D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000627:therapeutic use*; D000704:Analysis of Variance; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D002908:Chronic Disease; D018450:Disease Progression; D004359:Drug Therapy, Combination / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D005884:Gingival Hemorrhage / Q000188:drug therapy; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000627:therapeutic use*; D008875:Middle Aged; D010406:Penicillins / Q000627:therapeutic use*; D010508:Periodontal Abscess / Q000188:drug therapy; D017622:Periodontal Attachment Loss / Q000188:drug therapy; D010514:Periodontal Pocket / Q000188:drug therapy; D010518:Periodontitis / Q000188:drug therapy*; D010919:Placebos
chemical_list: D000890:Anti-Infective Agents; D010406:Penicillins; D010919:Placebos; D008795:Metronidazole; D000658:Amoxicillin