Systemic azithromycin as an adjunct to scaling and root planing in patients with stage III/IV periodontitis: 12-month results of a randomized controlled clinical trial.

OBJECTIVES: To determine whether azithromycin (AZI) as an adjunct to scaling and root planing (SRP), when compared to placebo, decreases the number of sites demonstrating pocket depth (PD) >/= 5 mm and bleeding on probing (BOP) 12 months post-treatment in stage III/IV periodontitis patients. MATERIALS AND METHODS: In a double-blind randomized parallel-arm placebo-controlled trial, 40 stage III/IV periodontitis patients received steps 1 and 2 of periodontal treatment in two sessions within 7 days. Patients then received systemic antibiotic therapy (n = 20; AZI 500 mg/day, 3 days) or placebo (n = 20). Additional instrumentation of residual diseased sites (DS) - sites with PD >/= 5 mm and BOP - was performed at the 3-, 6- and 9-month follow-ups. The primary outcome variable was the number of DS at the 12-month re-evaluation. Using a multivariate multilevel logistic regression model, the effects of gender, age, antibiotic therapy, presence of Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans, smoking, tooth being a molar and interdental location were evaluated. RESULTS: The number of DS after 12 months was similar in the test (median (Me) = 4, interquartile range (IQR) = 0-6) and control (Me = 3, IQR = 1-6.5) groups. Both groups showed substantial but equivalent improvements in periodontal parameters, with no intergroup differences at initially shallow or deep sites. The logistic regression showed a lower odds ratio (OR) for the healing of DS on molars (OR = 0.29; p < 0.001) and in smokers (OR = 0.36; p = 0.048). CONCLUSION: Stage III/IV periodontitis patients showed significant but comparable improvements in periodontal parameters and the number of residual DS at the 12-month revaluation regardless of treatment type. This may have been the result of the additional instrumentation received by patients at residual DS in both treatment groups. CLINICAL RELEVANCE: Treatment with AZI + SRP provided no additional benefits after 12 months in terms of periodontal parameters or the number of persisting sites with PD >/= 5 mm + BOP as compared to SRP plus placebo. TRIAL REGISTRATION: EUDRA-CT: 2015-004306-42; https://www.clinicaltrialsregister.eu/ctr-search/trial/2015-004306-42/SI , registered 17. 12. 2015.