Cyclic fatigue resistance of two nickel-titanium instruments in different curving angles: a comparative study

Abstract

The cyclic resistance of ProTaper Universal (size 25/08) and ProTaper Next (size 25/06) instruments was compared in artificial canals with different curvatures in this study. A total of 30 ProTaper Universal and 30 ProTaper Next instruments were divided into 6 groups (n = 10) and were operated into artificial canals with 3 different angles of curvature (45°, 60°, 90°). The canal length was kept consistent in this study. The number of cycles to fracture (NCF) was counted until file fracture occurred, at which point, the length of the fragment was measured. The data were analyzed statistically using ANOVA complemented by the Tukey test (p < 0.05). Cross sections of the fractured files were scanned by an electron microscope. In the fatigue test, the ProTaper Next displayed more resistance in 45° and 60° canals (p < 0.05), whereas ProTaper Universal exhibited a better operability in 90° canals (p < 0.05). The average length of the fragments from ProTaper Next was significantly shorter than that from ProTaper Universal in 90° canals (p < 0.05). The cross sections of the fractured surfaces became flatter when the curvature angles decreased from 90° to 45°. ProTaper Next was more reliable when shaping in curved canals, whereas ProTaper Universal was more sui for the preparation of root canals with severe curvatures.

Comparative Evaluation Of Cyclic Fatigue Resistance Of Protaper NEXT And Reciproc R Rotary Files In Simulated Canals With Angle Of Curvatures At 45° And 60°: An Invitro Study

“…Similar results were shown in the study conducted by Cheng Peng et al , ProTaper NEXT files tended to be more resistant when operated in 45°and 60° canals, Considering that the majority of root canals are closer to being 45°or 60° artificial canals. 10 Another study conducted by Huseyin Sinan et al revealed that PTN X2 instruments exhibited greater cyclic fatigue resistance in the apical curvature of an artificial canal with a double curvature 11 ,which is in accordance with the present study.…”

Analysis of Surface Characteristics of ProTaper Universal and ProTaper Next Instruments by Scanning Electron Microscopy

“…Other studies have demonstrated a change in the surface of rotary instruments after use ( 8 ). Although many previous studies have investigated various aspects of the ProTaper Next™ and ProTaper® Universal files, which include canal shaping ability ( 9 ), cyclic fatigue resistance ( 10 ), amount of debris extruded ( 11 ) etc., no studies have investigated how the surface and the alloy features would affect instrument fracture. Hence, the aim of this study was to analyze surface irregularities of these two rotary files before use and after instrumentation in curved canals in extracted human teeth.…”

Analysis of cyclic fatigue resistance of ProTaper Universal and ProTaper Next rotary instruments

“…The results of our study are correlated with the results of the study conducted by Mohamed et al [25] who compared the cyclic fatigue resistance of five different NiTi rotary instruments. In the study by Peng et al [15], the fragment length of ProTaper Next instruments was significantly smaller compared to ProTaper Universal when they were examined in the canal at an angle of 90 degrees. However, there was no statistically significant difference in the length of fractured fragments in canals at an angle of 45 and 60 degrees.…”

“…The instruments are expected to be flexible and have a high cutting efficiency, which would ensure preservation of the initial form of the canal. However, sudden fracture of instruments inside the root canal is a major concern in daily clinical practice [15]. Cyclic fatigue is the main reason of instrument fracture occurring at the point of maximum instrument flexure while rotating within curved root canals [16].…”