Influence of the semiconductor TiO2 on Streptococcus mutans

Objectives: It is known that the semiconductor TiO2 has a bactericidal effect on Streptococcus mutans (S. mutans). Our study examined the influence of the TiO2 semiconductors specifically on S. mutans growth. Methods: S. mutans MT8148 was inoculated into phosphate-buffered saline solution. We directly inserted into the bacterial suspension either (a) a welding rod made of TiO2 (group S), or (b) a powder of TiO2, or (c) a stainless steel welding rod (group P, a control). S. mutans growth was estimated on Mitis Salivarius agar medium after anaerobic incubation for 48 h. A biofilm of S. mutans was observed using confocal laser scanning microscopy (CLSM) after incubation with TiO2 powder. In addition, we obtained, at baseline, total counts of Streptococci and S. mutans from stimulated saliva. After 8 weeks, the suspensions containing the semiconductor TiO2 (group S) or the stainless steel (group P) were compared with baseline data. Plaque removed from teeth surface was evaluated by Patient Hygiene Performance (PHP). Results: No significant change in the bacterial count of S. mutans was found in solutions that had rods inserted. TiO2 powder had a pronounced propensity to kill S. mutans in biofilms. Compared to baseline and after 8 weeks, there were no significant changes in total Streptococci or S. mutans counts between group S and group P. The amount of plaque removed from teeth surface was greater for group S than for group P. Conclusion: Influence of the TiO2 was not observed in laboratory strain of S. mutans and number of total Streptococci as well as S. mutans in stimulated saliva.However, it is possible that TiO2 can influence biofilm formation of S. mutans. For prevention of dental caries, toothbrushes using semiconductor TiO2 have an effect on removal of plaque from teeth surface.