Antibacterial effect of ozone on cariogenic bacterial species

ObjectiveThe aim was to evaluate the antibacterial effect of ozone on cariogenic bacterial species with and without the presence of saliva and a possible effect on the salivary proteins.MethodsSuspensions of Actinomyces naeslundii (ACTCC 12104T), Lactobacilli casei (N CTC 151) and Streptococcus mutans (NCTC 10449), in salt buffer or in saliva, were exposed to ozone gas delivered by the ozone generator Healozone™ 2130C. Aliquots of the suspensions were taken after 10, 30 and 60 s ozone exposures and cultivated on agar plates. Initial number of bacteria per ml was 8.0 × 107 (SD 2.2 × 107) (A. naeslundii), 1.0 × 108 (SD 3.1 × 106) (L. casei) and 1.0 × 108 (SD 7.0 × 105) (S. mutans), respectively. The proteins were separated by SDS electrophoresis and visualized by silver staining.ResultsIn salt buffer 92%, 73% and 64% of the initial numbers of A. naeslundii, S. mutans and L. casei, respectively, were killed already after 10 s ozone exposure, while approximately 99.9% of the bacteria were dead after a 60 s exposure. After 10 and 30 s, but not after 60 s exposure to ozone, S. mutans and L. casei were less efficiently killed in saliva compared to the salt buffer. Various saliva proteins were degraded by ozone after a 60 s exposure.ConclusionsThe cariogenic species S. mutans, L. casei and A. naeslundii were almost eliminated following 60 s of ozone treatment. This killing was reduced in the presence of saliva although increasing the ozone application time to 60 s overcame these reductants in saliva. Detection of altered salivary proteins indicates that saliva components constitute additional targets for ozone.