PROPERTIES OF ENDODONTIC HAND INSTRUMENTS USED IN ROTARY MOTION .1. CUTTING EFFICIENCY

Cutting efficiency of 24 different types of endodontic hand instrument s, which are primarily designed for a rotary (reaming) working action, was investigated under standardized conditions, With a computer-drive n testing device, resin specimens with simulated cylindrical canals we re instrumented using a defined working motion simulating the clinical use of the instruments, Maximum penetration depth was the criterion f or cutting efficiency. Sample size was 12 instruments for each type an d size (#25 and #35). Nitinol K-files showed the least cutting efficie ncy, Stainless steel reamers and especially K-files showed better cutt ing efficiency than Nitinol K-files, Flexible stainless steel instrume nts displayed the best results. With regard to cutting efficiency, fle xible stainless steel instruments were clearly superior to stainless s teel reamers and K-files, and especially to Nitinol K-files.