Antimicrobial Activity of Newly Developed Root Canal Sealer Containing Titanium-Oxide

Objectives: Even after proper root canal enlargement and cleaning, there is a possibility that some kinds of bacteria would remain in the root canal system because of the complicated structure of root canals. Root canal filling materials with antimicrobial action, therefore, may be an effective way for keeping the root canal aseptic. Titanium Oxide (TiO₂) has lately attracted considerable attention as a new material in dentistry because of its catalytic activity and biocompatibility. In this study we developed a novel root canal sealer containing TiO₂ and evaluated its antimicrobial activity.

Methods: Components of the novel root canal sealer; Powder: 60% anatase-TiO₂ (synthesized), 40% alpha-TCP, Liquid: 60% polyacrylic acid, 15% propylene glycol, 25% distilled water. The physical properties of the sealer had satisfied the requirement of ISO formulation 6876. For comparison, we also examined Canals^®N, which is a popular sealer used in Japan, as a control. Six facultative anaerobic microorganisms were used for the antimicrobial test. The antimicrobial effects of each material were determined by measuring the diameter of zones of inhibition in millimeters. The results were statistically analyzed by using the Bonferroni test, with the level of significance set at 5%.

Results: The new sealer showed significant antimicrobial activity against all of the microorganisms used (p<0.01). It was observed that the powder of the sealer had significantly stronger antibacterial activity than that of Canals^®N. Although alpha-TCP had no antibacterial activity, the anatase-TiO₂ powder had remarkable antibacterial activity.

Conclusions: The newly developed root canal sealer containing anatase-TiO₂ possessed antimicrobial components that had to be released from the sealer matrix to be effective. The data suggest that the TiO₂ powder component of the sealer was responsible for the antimicrobial effects observed. As our new material showed excellent antibacterial characteristics, it might be quite suitable for clinical use as a root canal sealer.