Citation: Shieh, K.; Yang, J.; Zhu, E.H.; Peters, O.A.; Hosseinpour, S. Dentinal Tubule Penetrability and Bond Strength of Two Novel Calcium Silicate-Based Root Canal Sealers. Materials 2023, 16, 3309. https:// doi.org/10.3390/ma16093309 Academic Editor: Francesco Inchingolo Received: 26 February 2023 Revised: 15 April 2023 Accepted: 20 April 2023 Published: 23 April 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article Dentinal Tubule Penetrability and Bond Strength of Two Novel Calcium Silicate-Based Root Canal Sealers Karissa Shieh † , Jack Yang † , Elsa Heng Zhu † , Ove Andreas Peters * and Sepanta Hosseinpour * School of Dentistry, The University of Queensland, Brisbane 4006, Australia * Correspondence: o.peters@uq.edu.au (O.A.P.); s.hosseinpourdougolsar@uq.edu.au (S.H.) † These authors contributed equally. Abstract: Background: Once the chemo-mechanical preparation of root canals is finished, achieving a complete seal of the root canal system becomes crucial in determining the long-term success of endodontic treatment. The important goals of root canal obturation are to minimize leakage and achieve an adequate seal. Thus, a material that possesses satisfactory mechanical characteristics, is biocompatible, and has the ability to penetrate the dentine tubules adequately is needed. Aim: This study aimed to compare the penetrability and bond strength between two calcium silicate-based sealers and an epoxy resin-based sealer, as well as examine the relationship between penetrability and bond strength for the different sealers. Method and materials: Thirty-nine recently extracted single-rooted human premolar teeth were instrumented and divided evenly into three groups (n = 13), according to the sealer used for obturation: AH Plus Jet, EndoSequence, and AH Plus Bioceramic Sealer. Three teeth (30 slices) were randomly selected out of each for analysis using confocal laser scanning microscopy to assess penetrability. The remaining ten teeth (90 slices) in each group were subject to push-out tests using a universal testing machine. All teeth were sectioned into nine transverse slices of 0.9 mm thickness for their respective tests (apical, middle, coronal). Results: AH Plus Jet exhibited significantly lower penetrability and significantly higher bond strength compared to EndoSequence BC sealer (p = 0.002) and AH Plus Bioceramic Sealer (p = 0.006). There was no significant difference between EndoSequence BC sealer and AH Plus Bioceramic Sealer in terms of either penetrability or bond strength. No correlation was found between penetrability and bond strength. Conclusions: Within the limitation of this study and regardless of the location in the canal, the bioceramic based root canal sealers appeared to perform better than the epoxy resin-based sealer in terms of dentinal penetration rate. Further studies are required to compare other biomechanical properties of bioceramic sealers including setting characteristics and bacterial leakage. Keywords: penetration; bond strength; confocal; push-out test; calcium silicate-based sealer 1. Introduction Successful endodontic therapy is contingent on the proper disinfection and complete obturation of the root canal system [1]. Root canal sealers play a key role in creating a her- metic barrier between the canal wall and root filling material and in preventing pathogenic microorganisms and their by-products from infiltrating the canal space [2]. Reinfection of a root canal treated tooth is a leading cause of treatment failure and potentiates the need for laborious retreatment [3]. It is, therefore, important to evaluate the effectiveness of available and emerging sealers to both aid clinicians in making informed decisions about material selection and to contribute to the future research and development of endodontic sealers. Nowadays, there are many sealers available of differing chemical compositions. AH Plus Jet ® Root Canal Sealer (AH Plus) is an epoxy-resin-based sealer currently in wide use, owing to its excellent physical and handling properties [2]. As a result, it is often used as a benchmark to compare other formulations against. It is, however, not without its drawbacks, Materials 2023, 16, 3309. https://doi.org/10.3390/ma16093309 https://www.mdpi.com/journal/materials