Selective Effects of a Mouthwash Based on Pure Chlorine Dioxide. I. Effect on the Oral Mucosa and the Plaque Bacteria. Focused Review and Model Calculations

The health of the oral cavity is largely determined by the composition of microbial community, the oral microbiom, living there. An antimicrobial mouthwash must therefore serve two opposing purposes. On the one hand, it must prevent the overgrowth of microbes, especially pathogenic bacteria, that is, it must kill these microbes. On the other hand, it has to maintain a renewable oral flora of useful bacteria, and for this you have to save at least some of these bacteria. According to published experimental data, which are cited in this article, mouthwash based on pure chlorine dioxide has proven to be able to do this. In our series of articles, we examine what models/mechanisms can explain that mouthwash containing pure chlorine dioxide is able to meet these seemingly contradictory requirements. In addition to reviewing the literature data, we also raise rational hypotheses, which will have to be verified with further scientific and clinical studies in the future. In the first part of our series, we give a general overview of the experimental results published so far, as well as the possible mechanisms of the selectivity of chlorine dioxide. Based on experimental data and theoretical considerations, we point out that pure chlorine dioxide mouthwash has practically no effect on the mucous membrane, but it does affect the bacterial flora of the oral cavity. According to published data, a significant proportion of bacteria survive oral rinses, and rinsing kills pathogenic microbes more effectively than others. The latter can be explained by colonization resistance. Then, with the help of a model calculation based on the diffusion of ClO2 in plaque, we show that the majority of dental plaque bacteria cannot survive a 15-second mouth rinse with mouthwash containing 15 ppm ClO2. In other words, although the survival of a significant proportion of bacteria is obviously enabled by an oral biofilm, dental plaque cannot do so.