Effect of repeated treatment with sustained-release chlorhexidine mouth guards on salivary levels of mutans streptococci

The effect of multiple treatments with chlorhexidine mouth guards on salivary levels of mutans streptococci (MS) was studied. Eleven subjects with salivary MS ≤ 10⁵ CFU/ml were randomly assigned to an experimental or control group. Complete-arch mouth guards were coated internally with one of two ethylcellulose varnishes, one containing 30% dry w/w chlorhexidine and one containing no chlorhexidine. Subjects wore the mouth guards up to four times, each time for 7 consecutive nights while sleeping, with at least a 1-week break between treatment weeks. Subjects in the control group subsequently crossed over and also wore the chlorhexidine-containing mouth guards. Each of the week-long mouth guard sessions resulted in a reduction in mean salivary MS levels as follows (log₁₀ CFU/ml): for the experimental group, −1.0, −0.9, −1.0 and −1.2, and for the crossover group, −1.7, −0.6, −0.5 and −0.6. Salivary MS levels were (mean ± SD) 6.4 ± 0.5 at baseline and 3.8 ± 0.5 after the last mouth guard session for the experimental group and 6.0 ± 0.5 and 4.3 ± 0.7, respectively, for the crossover group. For the control group, there was no significant change in MS levels.