Evaluation of the long term antimicrobial effect of ozone

Objectives: The aim of this in vitro study was to evaluate the antimicrobial effect of HealOzone device on two different microorganisms, 2, 4 and 8 weeks after the treatment, using a tooth cavity model. Methods: Fourty-eight human third molars were divided into four groups (n=12 teeth). The enamel of the occlusal part of the teeth was removed and four cylindrical cavities were prepared on each tooth. The roots of the teeth were removed. After sterilization, the teeth were left in broth culture of 106 CFU/ml of microorganisms at 36°C for 48 hours for allowing the bacteria to invade the cavity. The first cavity of each tooth was used for control of the infection. Two of the groups (group A: control, group B: ozone treatment) were used for incubation with S.mutans and the other two (group C: control, group D: ozone treatment) for incubation with L.casei. After the ozone application (60s) the cavities were filled with composite resin and the teeth were kept in physiologic saline solution at 36°C. After 2, 4 and 8 weeks a restoration of each tooth was removed, dentin chips were collected with an excavator and the number of micro-organisms was determined. The data were statistically analysed (ANOVA, Tukey's, p<0.05). Results: For S. mutans a significant difference was found between the control and treated group (p=0.0021). The effect of ozone treatment was statistically different between the three tested periods (p=0.0003). As far as L.casei is concerned, the treatment with ozone did not exert any significant effect for each tested time period (2 weeks, p=0.134; 4 weeks, p=0.481; 8 weeks, p=0.134). Conclusions: HealOzone can provide a satisfying antimicrobial activity against S.mutans even 8 weeks after the treatment. For the time periods tested, L.casei was found to be resistant against the ozone treatment.