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Effectiveness of irrigation strategies on the removal of the smear layer from root canal dentin

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Abstract

The aim of this study was to evaluate the removal of the smear layer by some commonly used (needle-and-syringe irrigation, sonic activation, ultrasonically activated irrigation) and new root canal irrigation strategies (negative pressure irrigation and polymer rotary file) using a novel approach by comparing pre- and post-experimental images. Prepared root canals (n = 50) were subjected to a split tooth model and divided into 5 groups (n = 10): (1) needle-and-syringe irrigation (control); (2) sonic activation (SA); (3) negative pressure irrigation with continuous warm activated irrigation and evacuation (CWA); (4) polymer finishing file (FF); (5) ultrasonically activated irrigation (UAI). Smear layer scores and percentage of open dentinal tubules (%ODT) were evaluated by 2 examiners before and after irrigation procedures, from the middle and apical thirds of the root canal, on scanning electron microscopic images. Data were analysed using Kruskal–Wallis and post hoc tests at P = 0.05. Needle-and-syringe irrigation (control) showed no significant difference (both smear score and %ODT) compared to the pre-experimental value (P > 0.05). All other groups showed lower smear scores and higher %ODT, compared to the control (P < 0.05). The lowest smear score and highest %ODT were observed in the CWA group, which was significantly different from all other groups (P < 0.05). SA group showed significantly higher smear scores and lower %ODT than FF or UAI (P < 0.05). CWA showed superior removal of smear layer in the middle and apical thirds of the root canal compared to the other irrigation strategies.

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Acknowledgements

The authors sincerely thank Ms. Samantha Kar Yan Li, Centralized Research Laboratories, Faculty of Dentistry, The University of Hong Kong for the data analysis.

Funding

This study did not receive any funding from internal or external sources.

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Authors and Affiliations

  1. Discipline of Endodontology, Faculty of Dentistry, The University of Hong Kong, Pok Fu Lam, Hong Kong

    Prasanna Neelakantan & Gary S. P. Cheung

  2. Department of Endodontics and Restorative Dentistry, University of Siena, Siena, Italy

    Hani F. Ounsi & Simone Grandini

  3. Department of Endodontics, School of Dental Medicine, Lebanese University, Beirut, Lebanon

    Hani F. Ounsi

  4. Private Practice, Chennai, India

    Sharmila Devaraj

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  1. Prasanna Neelakantan
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  2. Hani F. Ounsi
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  4. Gary S. P. Cheung
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Correspondence to Prasanna Neelakantan.

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Neelakantan, P., Ounsi, H.F., Devaraj, S. et al. Effectiveness of irrigation strategies on the removal of the smear layer from root canal dentin. Odontology 107, 142–149 (2019). https://doi.org/10.1007/s10266-018-0373-2

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