Comparison of the Substantivity of Several Mouthwashesand their Effect on Microbial Plaque using Epifluorescence Microscope

Several techniques have been used to assess the efficacy and substantivity of mouthwashes. Considering the variability of available mouth rinses, this study aimed to assess the substantivity of several mouthwashes and their effect on microbial plaque using an epifluorescence microscope. This crossover double blind clinical trial evaluated 0.2%, and 0.12% (from 2 different brands) chlorhexidine (CHX), Persica and cetyl pyridinium chloride (CPC) mouth washes as well as normal saline as the negative control. Non-stimulated saliva samples were obtained from 16 candidates at baseline, 30s, 1, 3, 5 and 7h after one time use of mouthwashes. Epifluorescence technique was used to assess the viability of bacteria. For clinical examination following prophylaxis, subjects were asked not to use any oral hygiene measure except for the provided mouthwashes (twice a day) for 4 days. A 10-day washout period was allowed between the use of mouthwashes. Repeated measures ANOVA and Scheffe's test were applied for the comparison of viable bacterial count between the groups and Kruskal Wallis test was used for the assessment of microbial plaque. Persica and 0.12% CHX maintained their substantivity for 3 and 5h, respectively. A significant reduction in bacterial count was observed up to 7h after the use of 0.2% CHX only (P<0.001). On clinical examination, 0.2% and 0.12% CHX mouthwashes had significant differences with the others but had no significant difference with one another (P<0.02). Persica and CPC had similar efficacy (P<0.02). Efficacy of mouthwashes strongly depends on their substantivity. Daily application frequency of other mouth rinses should be increased in order to achieve an efficacy equal to that of CHX.