Methodological issues in randomized trials assessing probiotics for periodontal treatment.

BACKGROUND AND OBJECTIVE Probiotics traditionally used in medicine field are now being used in an attempt to control and treat periodontal disease. However, the trials used to analyze the effects of probiotics have been subject to methodological criticism. The aim of this review was to assess the methodological deficiencies in randomized controlled trials evaluating the efficacy and safety of oral administration of probiotics for the treatment of periodontal disease. MATERIAL AND METHODS A manual and electronic literature search (of MEDLINE and The Cochrane Library) was made, to March 2011, for randomized controlled trials presenting clinical, microbiological, immunological and patient-centered data for the efficacy of probiotics compared with a placebo/standard periodontal therapy for the treatment of periodontal disease. RESULTS The literature search yielded only four randomized double-blind, placebo-controlled studies that evaluated the efficacy of probiotics (using Lactobacillus reuteri and Lactobacillus salivarius probiotic strains) in patients with gingivitis. The studies were too methodologically flawed (of mediocre quality) with a high risk of bias for any meaningful conclusions to be reached. These studies lacked adequate descriptions of appropriate randomization, allocation concealment, blinding, formulation and dosage of probiotic and placebo, extent and severity of periodontal disease in patient populations, patient-centered outcomes, results data and potential confounding factors. CONCLUSION The existing randomized controlled trials have important methodological limitations; consequently, there is insufficient evidence to support the efficacy of probiotics in treating periodontal disease. More rigorous scientific research, in accordance with existing guidelines and research recommendations of the present review, is required to examine the safety and efficacy of probiotics before they are embraced in periodontal therapy.