Effects of Probiotic Therapy in the Treatment of Periodontitis: a Study of Clinical, Microbiological and Immunological Profile of the Host Response.

Before the study begins, the selected individuals will be identified by a numeric code and will receive instructions regarding oral hygiene as well as supragingival scaling in all teeth. According to a random numeric table generated by a computer software, the study coordinator will allocate each patient into one of the following groups: Control (Scaling and Root Planing - SRP) or Test (SRP + probiotic therapy). The subjects (Test and Control groups) will receive lozenge containing/not containing. In the Test group, the lozenge will present Bifidobacterium lactis HN019 (HN019). Individuals will be instructed (immediately after the first session of mechanical instrumentation) to consume twice a day for 4 weeks by dissolving the lozenge before bedtime, and when wake up. They will also be instructed not to consume other probiotic product during the study. Clinical, immunological and microbiological parameters will be assessed at baseline (pre-intervention) and after completion of non-surgical periodontal therapy 30 and 90 days. All patients will receive detailed information regarding the study (goals, benefits and risks) according to the Term of Consent. The sample size was determined using the software Graphpad Statemate 2.0 (GraphPad Software, Inc., San Diego, CA, USA). The ideal sample size to ensure an 80% power in the statistical analysis of the data obtained in this study was calculated considering the differences of means and standard deviations between the test and control groups of the study by Vivekananda et al. (2010). The α value was set at 0.05. The average dropout of patients in our previous studies (approximately 20%) was also considered to calculate the sample size. Thus, a sample size of at least 30 patients was considered appropriate for this study. The normality and homoscedasticity of the data obtained will be checked. Comparisons within groups and among groups at different time intervals will be performed through parametric or non-parametric appropriate tests. The significance level will be set at 5% in all tests. All calculations will be performed by SPSS software (SPSS, Chicago IL, USA).