Aim The purpose of the present study was to evaluate resistance to cyclic fatigue of new and used Profile Ni-Ti rotary instruments. Methodology Used instruments were operated in 10 clinical cases using passive instrumentation and a crown-down preparation technique. Cyclic fatigue testing of new and used engine-driven instruments was then performed with a specific device which allowed the instruments to rotate freely inside a stainless steel artificial canal, whilst maintaining conditions close to the clinical situation. Instruments were rotated until fracture occurred and time to fracture was visually recorded with a chronometer. Results A significant reduction of rotation time to breakage (life span) was noted between new and used instruments. In all sizes new instruments were significantly more resistant than used ones (two-sample t-test, P < 0.01). No instrument underwent intracanal failure during clinical use. Conclusions Prolonged clinical use of Ni-Ti engine-driven instruments significantly reduced their cyclic fatigue resistance. Nevertheless, each rotary instrument was successfully operated in up to 10 clinical cases without any intracanal failure.
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|Titolo:||Cyclic fatigue of ProFile rotary instruments after prolonged clinical use|
|Data di pubblicazione:||2001|
|Appartiene alla tipologia:||01a Articolo in rivista|