Fatigue resistance of engine-driven rotary nickel-titanium endodontic instruments.
A comparative study of the fatigue resistance of engine-driven nickel-titanium endodontic instruments was performed, aiming to access the influence of the cutting flute design and of the size of the files that reach the working length in curved canal shaping. Geometrical conditions similar to those found in practice were used. Series 29 #5 ProFile, together with #6 and #8 Quantec instruments, were tested in artificial canals with a 45-degree angle of curvature and 5-mm radius of curvature. It was observed that the size of the instrument, which determines the maximum strain amplitude during cyclic deformation, is the most important factor controlling fatigue resistance. The effect of heat sterilization on the fatigue resistance of the instruments was also examined. The results obtained indicate that the application of five sterilization procedures in dry heat increases the average number of cycles to failure of unused instruments by approximately 70%.
Chaves Craveiro de Melo
Marta
M
Faculty of Dentistry, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Guiomar de Azevedo Bahia
Maria
M
Lopes Buono
Vicente Tadeu
VT
D003722:Dental Alloys / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D004867:Equipment Design; D004868:Equipment Failure; D006244:Hardness; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D018709:Statistics, Nonparametric; D013242:Sterilization / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium