Evaluation of the Sealing Ability of a Dual-Cure Self-Adhesive Methacrylate Resin Sealer Using a Novel Bacterial Leakage Test Model

Background/Objectives: This study aimed to evaluate the bacterial invasion inhibitory ability of MetaSEAL Soft Paste, which is a root canal sealer that has good sealing properties in dye penetration tests, compared with conventional sealers, using a novel bacterial leakage test model. Methods: We compared MetaSEAL Soft Paste (methacrylate-based resin sealer) with Canals (zinc oxide-eugenol-based sealer), AH Plus Jet (epoxy-based resin sealer), and Dentalis NX (calcium hydroxide-based sealer). In the bacterial leakage tests, the center of the root of a bovine incisor was sliced horizontally. The area of the root canal prepared using a diamond point was filled with a sealer, and the specimen was placed on a brain heart infusion agar medium. Specimens with a filter paper disc containing Enterococcus faecalis were maintained until colonization was observed. The antibacterial properties of the sealers were evaluated using the agar diffusion test and the direct contact test. Results: AH Plus Jet tended to take the longest time to show colonies in the bacterial leakage test; however, this result was not significant compared with MetaSEAL Soft Paste. In the direct contact test, significantly fewer bacteria were detected in MetaSEAL Soft Paste and Canals than in AH Plus Jet or positive controls (p < 0.01). Conclusions: This study suggests that the novel bacterial leakage test model is effective for accurately evaluating the ability of sealers to prevent bacterial leakage, and further suggests that the sealing ability of MetaSEAL Soft Paste may not be superior to that of AH Plus Jet.