Purpose: To assess the effect of ozone on the microbial flora and clinical severity of primary root caries.
Methods: 26 patients with 70 primary root carious lesions (PRCLs) were entered. Each PRCL was classified in terms of color, cavitation, size, hardness, distance from the gingival margin and severity. Overlying plaque was then removed and each lesion dried. A biopsy was taken from half of each PRCL using a sterile excavator. Subsequently, the remaining lesions were exposed to ozone gas for a period of either 10 seconds (n = 35) or 20 seconds (n = 35) and a further biopsy was taken.
Results: Using a paired Student t-test, a significant (P < 0.001) difference (mean +/- SE) in total micro-organisms was observed in the ozone-treated samples after either a 10 seconds (log10 4.35 +/- 0.49) or 20 seconds (log10 0.46 +/- 0.26) ozone application compared with the control samples (log10 7.00 +/- 0.24) and (log10 6.00 +/- 0.21) respectively. Using Pearson's correlation tests, there were significant correlations for the reduction in total micro-organisms after 10 seconds of ozone application with cavitation, size, distance from gingival margin and severity of PRCLs (P < 0.05). In conclusion, ozone application either for 10 or 20 seconds dramatically reduced most of the micro-organisms in PRCLs without any side effects recorded at recall intervals between 3 and 5.5 months. Out of the 65 PRCLs reviewed, 33 lesions had become hard, 27 lesions reversed to severity index 1 from severity index 2, and five lesions remained the same following ozone application for a period of either 10 or 20 seconds.