Caries means demineralization with the formation of cavities and pulp symptoms and necrosis as an end result. The acids in the mouth are mainly produced by oral bacteria like Streptococcus mutans from bacterial biofilms adhering to the tooth. Ozone has been shown to have a very strong bactericidal effect on bacteria causing dental caries. Baysan et al reported that there was a statistically significant reduction of streptococci in root caries lesions and saliva samples after ozone application. The positive clinical effect of ozone with respect to arresting caries progression and the remineralization of caries has been shown in vitro and in vivo. In an in vivo study, Baysan and Lynch found that the application of ozone resulted in a significant reduction of bacterial contamination as well as a reduction in size and severity of root caries lesions. In a subsequent study, Baysan and Lynch reported that the severity of root caries lesions was significantly reduced after ozone application as measured by electrical conductance and laser fluorescence. In several studies, the caries reducing effect of ozone was measured with biochemical methods in root surface caries lesions, the biofilm and saliva after ozone application. See Citation section for references.