Microhardness of root dentin depending on root canal treatment technique

Purpose. To analyze literature on the influence of mechanical and chemical root canal treatment and methods of activating irrigation solutions on the microhardness of root dentin.
Material and methods. Literature search was conducted in PubMed, E-library, CyberLeninka, Google Scholar, and Wiley Online Library databases on September 3, 2023, and March 2, 2025, using keywords. Articles in English and Russian were selected for analysis. Inclusion criteria: original articles in periodicals, in vitro and in situ studies, studies on extracted human teeth, studies assessing the microhardness of dentin. The search in the PubMed database yielded 83 publications, 109 were found in the e-library scientific electronic library, 12 in the CyberLeninka database, 141 in Google Scholar, and 217 in the Wiley online library. After excluding duplicates and evaluating the inclusion/exclusion criteria, 17 articles remained.
Results. A review of the literature on the effects of mechanical processing showed that rotary tools remove more dentin than hand tools; reciprocating tools remove more dentin than tools with continuous rotation; TruNatomy files are the safest among rotary tools in terms of dentin microhardness. The use of sodium hypochlorite at a concentration of 2.5% or greater leads to an irreversible decrease in the microhardness of dentin, regardless of the use of ethylenediaminetetraacetic acid (EDTA), although 5% EDTA showed the smallest decrease in the microhardness of dentin. A significant decrease in microhardness was observed in the root canals that underwent ultrasonic activation.
Conclusion. Based on the analyzed literature, we found that all rotary tools, as well as the use of sodium hypochlorite 2.5% or greater and EDTA 17%, lead to a decrease in the microhardness of dentin. The influence of irrigation solution activation techniques on root dentin microhardness has not been sufficiently studied and requires further investigation.
Key words: microhardness of root dentin, hardness of root dentin, strength of root dentin, mechanical treatment of root canal, chemical treatment of root canal, amount of mineral components of dentin, irrigation, ultrasonic activation, sound activation, endoactivator
Conflicts of interest. The authors have no conflicts of interest to declare.
Financing. The study received no funding.