OBJECTIVES: This study evaluated the effects of curvature location along an artificial canal on @entity1295 ( @entity1295 ) of an Mtwo rotary instrument, verifying the number of cycles to fatigue @entity174 (NCF) and morphologic characteristics of the fractured instruments. STUDY DESIGN: @entity1295 testing of instruments was performed in artificial canals with curvature radii of 10 mm and arc lengths of 11 mm. Mtwo rotary instruments size 40, 0.04 taper were used in 2 groups (n = 10): group A, curvature positioned on middle part; group B, apical curvature. All instruments were rotated until @entity174 . The number of cycles to failure was registered. Data were analyzed by independent sample t test. Fractured surfaces and the helical shafts of the instruments were analyzed by scanning electron microscopy. RESULTS: NCF for groups A and B had significant statistic differences (P < .05). The highest values were found in the group where the curvature was positioned on the apical part of the canal. No plastic deformation was observed on the helical shafts. CONCLUSIONS: The number of cycles to @entity174 of the Mtwo instruments increased when the arc was changed from the middle to the apical part of the canal. The morphologic characteristics of the fractured surfaces were of the ductile type.

Influence of curvature location along an artificial canal on XXXX of a rotary nickel-titanium endodontic instrument.

@entity1295 :: ('MESH:D005221', 'Disease') :: ['cyclic fatigue', 'CF'] @entity174 :: ('MESH:D050723', 'Disease') :: ['fracture']
@entity1295 :: (MESH:D005221,Disease) :: ['cyclic fatigue']
