Cutting efficiency loss of root canal instruments due to bulk plastic deformation, surface damage, and wear.
Cutting efficiency loss of #15 H-type and K-type files was studied as a function of bulk plastic deformation and cutting edge wear. Instrumentation was done by purely extractive filing, without any significant torsional and/or bending strain. Cutting efficiency variations were assessed by means of cutting force measurement, while absolute cutting efficiency was obtained through three-dimensional scanning stylus profilometry. Bulk plastic deformation-induced flute modifications may lower the cutting efficiency of H-type files by approximately 50%. For this instrument special care is required in tip and flute machining to avoid in vivo breakage. On the contrary, within the normal life-span of an instrument of approximately 100 strokes cutting edge wear is seen to be negligible. The existence of such wear is "inferred" indirectly from a 10% drop in extraction efficiency.
Yguel-Henry
S
S
von Stebut
J
J
D003762:Dental Instruments; D003799:Dental Stress Analysis; D004867:Equipment Design / Q000592:standards; D004868:Equipment Failure; D008855:Microscopy, Electron, Scanning; D012390:Root Canal Therapy / Q000295:instrumentation*; D013499:Surface Properties