Quasi‐3D dynamic photoelastic analysis of stress distribution during preparation of simulated canals with 13 mechanical preparation systems

This study compared the impact of stress on simulated canal walls using nine rotary and four reciprocating systems. Sixty-five transparent blocks with curved canals were grouped by systems. Intra- and inter-observer agreement was high. Most instruments had acceptable performance, but some, like HyFlex EDM 25.12 and Reciproc Blue R25, showed high-stress scores. Statistical analysis found significant differences among systems at different canal thirds. In conclusion, no protocol was stress-free; varying stress levels existed, influenced by factors like taper and motion. Instruments with larger taper, lower speed, reciprocation, and heat-treated NiTi alloy had higher stress patterns.