The Ability of Root Canal Cleaning and Shaping Procedures to Initiate Dentinal Radicular Microcracks

The ability of nickel-titanium rotary instruments to initiate dentinal defects during root canal shaping is contradictory. The type of their alloy, taper, tip design, cross-section and kinematics are analyzed in terms of generating unfavorable stress onto the root canal wall. Along with their positive characteristics, some of the most common irrigant solutions for chemical disinfection and removal of debris - sodium hypochlorite and ethylenediaminetetraacetic acid are reported to contribute to dentinal defect formation and to reduce the microhardness of radicular dentin. The effects of the aforementioned irrigants on dentinal matrix in terms of their concentration and application time are overviewed.