Effect of Endodontic Irrigants on Root Dentin Microhardness: A Systematic Review

Removal of the organic and inorganic components of the smear layer in the course of the endodontic treatment is achieved by the use of different endodontic irrigants. Despite their favorable disinfection abilities, they are reported to alter the biomechanical properties of root canal dentin. The aim of this article is to critically review published in vitro studies comparing effects of different irrigation regimes on dentinal microhardness and to identify, synthesize, and analyse the data available over the five-year period from March 2015 to March 2020. The literature search was done on PubMed - MEDLINE, The Cochrane Library and Science Direct database, then the articles were assessed by two independent reviewers. A total of thirteen papers out of 134 titles met the eligibility criteria. All studies reported reduction of root dentin microhardness after treatment with various endodontic solutions. EDTA reduced dentin microhardness to a greater extent in comparison with other solutions regardless of the application time and the total amount of the chelating agent. Photon-Induced Photoacoustic Streaming proved to be a safe method for additional activation of disinfection solutions.