The aim of this randomized placebo- controlled clinical trial is to evaluate the effects of Lactobacillus rhamnosus SP1- containing probiotic sachet as an adjunct to scaling and root planning (SRP). Material and methods: Thirty six gingivitis patients will be recruited and monitored clinically and microbiologically at baseline and 3-6 months after therapy. All patients will receive scaling and periodontal treatment and randomly will be assigned over an experimental (SRP + probiotic, n=18) or control (SRP + placebo, n=18) group. The sachet will be used once per day during 3 months.

Gingivitis is the most prevalent worldwide periodontal disease, is characterized by inflammation of the tissues surrounding the tooth without causing periodontal attachment loss. Preventive and / or therapeutic measures to facilitate or improve their control are therefore very important, much more if you consider that gingivitis and periodontitis are considered part of an ongoing inflammatory process. Treatment of gingivitis, like that of all periodontal diseases has been based on the implementation of control measures personal and professional plaque. Notwithstanding the foregoing, it has been reported that although mechanical therapy achieved significantly decrease the periodontopathogens, this may be only temporary since bacteria can recolonize the treated niches in the oral cavity. In this context, it has emerged as a new treatment strategy complementary use of probiotics such as Lactobacillus rhamnosus, which possess anti-bacterial and anti-inflammatory properties. Generally speaking, probiotics would promote health by competitive exclusion of some or positive pathogenic bacteria. Objective: To evaluate the effect of the administration of Lactobacillus rhamnosus as an adjunct to conventional periodontal therapy in adolescent and young adult patients with gingivitis. Methodology: A randomized double-blind clinical trial to evaluate the effect of sachet probiotic Lactobacillus rhamnosus as an adjunct to conventional periodontal treatment of patients with gingivitis will be performed. Expected Results: Statistically significant decrease in levels of periodontopathogens (P. gingivalis, A. actinomycetemcomitans, T. forsythia and A. viscosus) in the experimental group compared with the control. Association between clinical and microbiological parameters.

Inclusion Criteria:

• Diagnosis of Gingivitis
• Gingival index > 1.5 (> 10 % of the sites examined)
• Index increased bleeding on probing 10% of the sites surveyed
• Probing Depth < 3 mm
• Systemically healthy (except for the presence of gingivitis)
• Patients who have not received periodontal treatment and before no intake of medicines such as antibiotics and / or anti-inflammatory in the last 3 months prior to the start of the study

Exclusion Criteria:

• Patients who develop systemic disease during the study.
• Patients who have to ingest antibiotics and / or antiinflammatories during the study.
• If you are a woman becomes pregnant during the study.