Cyclic Fatigue Resistance of Different Glide Path Files in Simulated Double Curved Canal in Continuous Rotary Motion: An In Vitro Study.

AIM: This in vitro study aimed to compare and evaluate the resistance to cyclic fatigue of a newly developed glide path file in a simulated double curvature canal in a cyclic fatigue-testing machine. METHODS: In this in vitro study, a static cyclic fatigue-testing machine with a simulated double curve was created and the samples were divided into the following three groups: Group I-HyFlex EDM; group II-TruNatomy file; and group III-Aurum G files and each instrument is continued to rotate in the canal and a number of cycles to failure (NCF) was calculated and Fractographic analysis was done using scanning electron microscope (SEM), and the results were statistically analyzed. RESULTS: Statistical analysis was done using parametric methods one-way analysis of variance (ANOVA) shows statistical significance between groups and then Tukey's HSD post hoc tests were used for multiple pairwise comparisons. TruNatomy glide path files had the highest cyclic fatigue resistance when compared to HyFlex EDM and Aurum G files. CONCLUSION: The selection of file systems in cleaning and shaping protocols is an enigma to endodontics. From the results of this study, it can be concluded that TruNatomy files had higher cyclic fatigue resistance than other glide path files are canals with double curvature, hence it is suitable for usage in root canals with extreme curvature. CLINICAL SIGNIFICANCE: The selection of file systems in cleaning and shaping protocols is an enigma to endodontics. This in vitro study explored the selection protocols for the execution of root canal preparation. Heat treatment of nickel-titanium (NiTi) endodontic files had improved the cyclic fatigue resistance significantly enhancing the clinical life of file systems.

Evaluation of Root Dentin Thickness and Smear Layer Removal Efficacy of Two Novel Nickel Titanium Rotary Instruments - An In Vitro Cone-Beam Computed Tomography and Scanning Electron Microscopy Study.

OBJECTIVE: This study aimed to compare the two nickel-titanium (NiTi) instruments on root dentin thickness using cone-beam computed tomography (CBCT) and ability to remove the smear layer using scanning electron microscope (SEM). MATERIALS AND METHODS: The effect of two NiTi rotary instruments such as XP Endo shaper and ProTaper Gold (PTG) in retaining adequate dentin thickness and debridement (i.e., removal of smear layer) was evaluated in vitro using CBCT and SEM. After cleaning and shaping of the root canal with adequate irrigation, the effect of two NiTi instrument systems at 3 mm (apical), 6 mm (middle), and 9 mm (coronal) levels on buccal, lingual, mesial, and distal aspects in terms of amount of dentin removal and smear layer removal was evaluated. The data were analyzed using student's unpaired t-test with a significance of P ≤ 0.05. RESULTS: Both NiTi instrument systems had no statistically significant difference in amount of dentin removal at all three levels and on all four aspects. In smear layer removal, PTG had significantly better efficacy compared to XP Endo shaper at the coronal third of root canal. CONCLUSION: Instrumentation with XP Endo Shaper and PTG showed a similar amount of dentin removal. PTG has a significant effect on smear layer removal compared to XP Endo Shaper only at the coronal third of root canal.