Staining and calculus formation after 0.12% chlorhexidine rinses in plaque-free and plaque covered surfaces: a randomized trial

OBJECTIVES Studies concerning side effects of chlorhexidine as related to the presence of plaque are scarce. The purpose of this study was to compare the side effects of 0.12% chlorhexidine gluconate (CHX) on previously plaque-free (control group) and plaque-covered surfaces (test group). METHODS This study had a single-blind, randomized, split-mouth, 21 days-experimental gingivitis design, including 20 individuals who abandoned all mechanical plaque control methods during 25 days. After 4 days of plaque accumulation, the individuals had 2 randomized quadrants cleaned, remaining 2 quadrants with plaque-covered dental surfaces. On the fourth day, the individuals started with 0.12% CHX rinsing lasting for 21 days. Stain index intensity and extent as well as calculus formation were evaluated during the experimental period. RESULTS Intergroup comparisons showed statistically higher (p<0.05) stain intensity and extent index as well as calculus formation over the study in test surfaces as compared to control surfaces. Thus, 26.19% of test surfaces presented calculus, whereas calculus was observed in 4.52% in control surfaces. CONCLUSIONS The presence of plaque increased 0.12% CHX side effects. These results strengthen the necessity of biofilm disruption prior to the start of CHX mouthrinses in order to reduce side effects.