Ozone, either in gaseous form or as ozonated water, has been available for use as a treatment for dental caries for a decade. This paper reviews the literature on the subject by examining the findings of publications in the peer review literature. Eighteen papers were identified by a literature search. From the review of these, it was concluded that, while some laboratory studies and some short duration clinical studies have suggested that ozone may be effective in the treatment of root caries or killing of oral micro-organisms, the clinical evidence for the use of ozone in treatment of caries is not compelling.