The aim of the study is to compare the effect of a suspension containing chlorhexidine and alcohol and another one containing clorhexidine with no alcohol in dynamic of the subgingival biofilm formation versus a Placebo suspension. The initial subgingival biofilm formation will be evaluated by means of Plaque Free Zone (PFZ).

This is a double blind, cross over, randomized clinical trial. 35 volunteers will stop mechanical supragingival biofilm removal measures for 96h following a complete scaling and polishing of the tooth surfaces. During this period they will be asked to rinse for a minute a Solution containing chlorhexidine and alcohol or a solution with chlorhexidine alcohol-free or placebo. Every 24h the presence of deposits will be registered with special attention to the presence of a plaque free zone between the apical border of the deposits and the gingival margin. Absence of deposits is scored 0, presence of deposits and plaque free zone =1 and presence of deposits and absence of plaque free zone =2 (MALISKA, A. N. et al. Measuring early plaque formation clinically. Oral health preventive dentistry, v. 4, p. 273-278, 2006). The prevalence of scores and the rate of changes from scores 0 and 1 into 2 will be evaluated for significance. Sample size was calculated taking the results from the study o MALISKA, AN (2006) as reference.

Inclusion Criteria:

• age from 18 years;
• non-smokers;
• have good general health;
• present at least 20 natural teeth in the mouth, including the incisors, canines and premolars without restorations, crowns, gingival recession, anatomic defects, gingivitis e/or periodontitis.

Exclusion Criteria:

• • positive history of using antibiotic e/or anti-inflammatory drugs in the month previous to the initial consultation;

  • positive history of allergies at using Triclosan;
  • pregnant or lactating patients;
  • patients in use of fixed orthodontic appliance.