Development of a New Root Canal Sealer Using Zinc Oxide, Eugenol, and Oleic Acid

抄録

 Purpose: Eugenol, found in zinc oxide eugenol (ZOE), a commonly used root canal sealer, has antibacterial properties. However, eugenol can irritate tissues when used in high concentrations. A new ZOE sealer was developed by diluting eugenol with oleic acid to reduce the harmful effects of eugenol, which is released after filling, on periapical tissues. This study aimed to investigate the physical properties and antibacterial effects of this new ZOE sealer.

 Methods: Tests were conducted on the hardening time, flow behavior, radiopacity, solubility, and sealing ability of this new ZOE sealer in accordance with International Organization for Standard (ISO) 6876, and these values were compared with a commonly used control ZOE sealer (Canals). Further, tests related to the clinical application of this sealer were conducted, including a size change test, a test of time-dependent changes in hardness of the sealer immersed in water, a bacterial growth prevention test using three types of bacteria, and a test of sealer effects on curing for two types of composite resins.

 Results: The new ZOE sealer met the requirements of ISO 6876 for all test results except radiopacity. Setting time was shorter for the new ZOE sealer than for the control ZOE sealer, and was within 30 minutes. Viscosity was lower for the new sealer than for the control sealer. Disintegration ratios showed no significant difference between sealers. Unlike the control sealer, the new sealer did not show any dye penetration. The volume of the new sealer, unlike the control sealer, showed a tendency to continuously increase from 7 to 30 days after mixing. No significant difference in hardness was seen between the new and control sealers. Although the amount of eugenol in the new sealer was one-fifth that of the control sealer, antibacterial effects against Prevotella intermedia and Porphyromonas gingivalis were similar to those of the control sealer. The new sealer did not cause any significant change in the curing of composite resins, whereas the control sealer significantly inhibited curing.

 Conclusion: The new ZOE sealer, developed by reducing the eugenol content of the sealer to approximately 30％ using oleic acid and isostearic acid, is clinically applicable because it expands and cures gently, retains antibacterial properties, and does not inhibit the curing of composite resins.