Influence of Canal Preparation Taper on the Push-Out Bond Strength and Failure Mode of Epoxy Resin- and Calcium Silicate-Based Sealers: An In Vitro Study

Abstract

Root canal preparation taper may influence sealer–dentin interfacial behavior; however, its effect on sealer bond strength remains insufficiently investigated. This study evaluated the influence of 0.04 and 0.06 preparation tapers on the push-out bond strength and failure mode of epoxy resin- and calcium silicate-based sealers. Forty human mandibular incisors were prepared to size 40/0.04 or 40/0.06 and subdivided according to the sealer used (AH Plus or TotalFill BC; n = 10). Canals were filled with sealer only, and slices obtained from the middle and apical root levels were subjected to push-out testing and failure-mode analysis. Sealer type, preparation taper, and root level significantly affected push-out bond strength (all p < 0.001), with a significant sealer × taper interaction (p = 0.007). Increasing taper from 0.04 to 0.06 significantly increased AH Plus bond strength at both root levels, whereas TotalFill BC showed no significant taper-related differences after Bonferroni correction. With 0.06 taper, AH Plus demonstrated significantly greater bond strength than TotalFill BC at both root levels, whereas no significant sealer differences were detected with 0.04 taper. Bond strength was generally higher at the middle level. Preparation taper therefore influenced push-out bond strength in a sealer-dependent manner, indicating that preparation geometry and sealer type interact in determining sealer–dentin interfacial behavior.