Influence of the type of reciprocating motion on the cyclic fatigue resistance of reciprocating files in a dynamic model

Cyclic Fatigue Resistance of Rotary versus Reciprocating Endodontic Files: A Systematic Review and Meta-Analysis

(1) Background: The failure of nickel-titanium (NiTi) rotary files is a complication related to endodontic instruments. The aim of this study was to compare the resistance to cyclic fatigue between rotary and reciprocating file systems. (2) Methods: Specific PICO: Population (P): artificial root canals; Interventions (I): instrumentation with NiTi rotary and reciprocating files; Comparison (C): rotary versus reciprocating files; Outcome (O): cyclic fatigue resistance. Studies were identified through bibliographic research using electronic databases (Medline, Embase, Scopus, SciELO, and WOS). The studies were combined using a random effects model by the inverse variance method. The effect size was the mean of the time to fracture (TTF) and number of cycles to fracture (NCF). Heterogeneity was assessed using the p value of the Q test for heterogeneity and the I2. (3) Results: TTF for rotary files was determined in 474.5 s and 839.1 for reciprocating without statistically significant differences. NCF for rotary systems was determined in 1444.2 and for reciprocating file systems in 4155.9 with statistically significant differences (p = 0.035), making reciprocating files more resistant. (4) Conclusions: Reciprocating files have better resistance to cyclic fatigue than rotary files. When tested in double curvature canals, reciprocating files also showed higher resistance.

Impact of pecking amplitude on cyclic fatigue of new nickel-titanium files

OBJECTIVES

The aim of this study is to determine the cyclic fatigue resistance of Mtwo Minimal in static and dynamic tests, with different amplitudes of pecking movements, at intracanal temperature.

MATERIALS AND METHODS

Two hundred new 25-mm Mtwo Minimal rotary files (#10/0.035, #17.5/0.045, #25/0.05, #40/0.03, #45/0.03) were tested in static and dynamic cyclic fatigue tests at 35°C (±1°C). An artificial stainless-steel canal was used. In the dynamic mode, axial movements were set at 1 and 3 mm. The number of cycles to fracture (NCF) was recorded and statistically analyzed by one-way analysis of variance (p < 0.05).

RESULTS

The 3-mm dynamic test showed significantly increased NCF than the other tests for the #10/0.035, #17.5/0.045, and #25/0.05 files (p < 0.05). The #40/0.03 and #45/0.03 files showed no significant differences in all the tests (p > 0.05).

CONCLUSION

Mtwo Minimal showed higher cyclic fatigue resistance in the dynamic test than the static test, except for the larger instruments. The 3-mm pecking amplitude increased the cyclic fatigue resistance of the smaller instruments.

An Appraisal on Newer Endodontic File Systems: A Narrative Review

AIM

This narrative review aims to explore and elicit the newer endodontic file systems used for root canal treatments.

BACKGROUND

The primary goals of endodontic therapy continue to be the mechanical enlargement and shaping of the intricate endodontic root canal systems to aid in disinfection. Nowadays endodontists have access to a wide range of endodontic file systems for root canal preparations with various design characteristics and benefits.

REVIEW RESULTS

ProTaper Ultimate (PTU) files' tip have a triangular convex cross-section, an offset mass of rotating design, a maximum flute diameter of 1.0 mm, and are constructed of gold wire, hence, commonly applied in conditions with restricted accessibility or an extremely curved canal. TruNatomyhas advantages over other cutting-edge file systems like maximum flute diameter of the corona, reduced distance between active cutting flutes, and shorter handles in comparison to SX instruments. In comparison to PTU files, ProTaper Gold (PTG) files are noticeably more elastic and fatigue-resistant. Compared to files in the F1-F3 range, size S1 and S2 files have a significantly longer fatigue life. MicroMega One RECI is more resistant to cyclic fatigue because of its heat treatment and reciprocating action and the C-wire heat treatment of the former gives it flexibility and controlled memory, enabling the prebending of the file. The RECIPROC blue demonstrated enhanced flexibility, increased fatigue resistance, and lower microhardness while maintaining the same surface qualities.

CONCLUSION

As per the necessity and requirement on case to case basis, every endodontic file system has advantages and disadvantages as mentioned in this narrative review. According to the need, an endodontist can select the file system which is required specifically. Although several studies are comparing these various systems in the literature, this narrative review aims to give the clinician a summary of some recently launched endodontic rotary file systems available in the market and their clinical uses.

CLINICAL SIGNIFICANCE

As per the priority and need of the case, whether removal and extrusion of debris, reduction of micro-organisms, keeping canal anatomy, and cutting efficiency, a specific required file system can be utilized.

Analysis of the Importance of the Motion Used in the Resistance of Different Mechanical Instrumentation Systems in Endodontics: A Comparative Study

Aim: The aim of this study was to compare the cyclic fatigue strength of different reciprocating rotary systems depending on the movement used. Methods: Four study groups were analyzed (n = 30): (1) Reciproc®, (2) Reciproc Blue®, (3) Wave One Gold® and (4) Procodile®. Each group was divided into three subgroups according to the motion used: (A) Reflex Dynamic® (n = 10), (B) ReFlex Smart® (n = 10) and (C) conventional reciprocating motion (n = 10). They were used in a dynamic cyclic fatigue prototype until their fracture, and the time was measured in seconds. The results obtained were analyzed with the ANOVA method, and for two-to-two comparisons, the Tukey method and Weibull statistics were used. Results: Procodile ReFlex Smart had the longest time to failure, and statistically significant differences were found between Procodile ReFlex Smart and the other files and motions (p < 0.05). Conclusion: Smart motions increase cyclic fatigue strength. ReFlex Smart® motion increases the cyclic fatigue strength of reciprocating rotary systems, and Procodile® ReFlex Smart was the most resistant system file.

A Novel Digital Technique to Analyze the Wear of CM-Wire NiTi Alloy Endodontic Reciprocating Files: An In Vitro Study

The present study seeks to describe a novel digital measurement technique for analyzing the wear volume of controlled memory (CM)-wire NiTi alloy endodontic reciprocating files after clinical use. Material and Methods: Ten CM-wire NiTi endodontic reciprocating files were randomly used in ten first upper molar teeth within four root canals. The CM-wire NiTi alloy endodontic reciprocating files were subjected to preoperative and postoperative micro-computed tomography (micro-CT) scans to obtain accurate digital imaging and communication on medicine (DICOM) digital files, which were segmented using intensity-based thresholding and an exclusive OR (XOR) logical operation (Boolean algebra logical operator) to obtain a mask of the location to localize and quantify the wear volume of the CM-wire NiTi alloy endodontic reciprocating files. Gage repeatability and reproducibility statistical analysis was applied to assess the reproducibility and repeatability of this measurement technique. Results: The analysis showed a repeatability and reproducibility of 0.00% for the digital measurement technique used to analyze the wear volume of CM-wire NiTi alloy endodontic reciprocating files after clinical use. Wear was mostly identified at the tip and cutting edges of the CM-wire NiTi alloy endodontic reciprocating files. Conclusions: This novel digital measurement technique is a repeatable, reproducible, and accurate method of quantifying the wear volume of CM-wire NiTi alloy endodontic reciprocating files after clinical use.