The Effect of Chlorine Dioxide (ClO₂) on Different Cariogenic Microorganisms

Various antimicrobial agents are used in order to reduce high levels of cariogenic microorganisms. Objectives: The aim of the present investigation was to evaluate the effect of a new stabilized form of chlorine dioxide (ClO₂) on different oral bacteria both in vitro and in vivo. Methods: The minimal inhibitory concentration (MIC) was studied for 16 different oral laboratory strains. In an in vivo study, 12 subjects participated in a 14-day randomized trial. The subjects rinsed 4 times daily for 2x1 min with 10 ml of 40 ppm ClO₂ (XINIX^®, XINIX AB, Stockholm, Sweden). 1% chlorhexidine (CHX) and distilled water were used as controls. Salivary samples were collected day 0, 3, 7 and 14 and plaque samples day 0 and 14 for determination of total number of CFU, oral streptococci, mutans streptococci, lactobacilli, Actinomyces and Candida. Results: Low MIC-values were found for S. sobrinus and S. mitis, while strains of S. mutans, S. sanguis, S. salivarius, lactobacilli, Actinomyces and Candida were less susceptible. Most of the studied microorganisms in saliva were numerically reduced from day 0 to 14 during frequent rinses with both ClO₂ and CHX. However, only CHX showed statistically significant reduction for total number of CFU (p<0.01), oral streptococci (p<0.01) and mutans streptococci (p<0.001), while no such effect was found for lactobacilli, Actinomyces and Candida. For plaque, both ClO₂ and CHX reduced the total number of CFU, oral streptococci and % mutans streptococci (p<0.001 or p<0.05). Conclusions: The main conclusion from this study is that the new stabilized form of chlorine dioxide can reduce several of the oral microorganisms associated with dental caries in vitro and in vivo. However, the reduction was not of the same magnitude as what was found for chlorhexidine. This study was supported by Patentmedelsfonden för Odontologisk Profylaxforskning and XINIX AB, Sweden.