Comparative evaluation of the shaping ability of single-file system versus multi-file system in severely curved root canals

Shaping Efficiency of Rotary and Reciprocating Kinematics of Engine-driven Nickel-Titanium Instruments in Moderate and Severely curved Root Canals Using Microcomputed Tomography: A Systematic Review of Ex Vivo Studies

INTRODUCTION

This systematic review aimed to compare reciprocating with continuous rotary instrumentation kinematics, by means of microcomputed tomography evaluations, in extracted human permanent teeth with moderate and severe canal curvatures.

METHODS

The research protocol was registered in the International Prospective Register of Systematic Reviews and given the reference number CRD42023404035. An electronic search was undertaken in MEDLINE (PubMed), EBSCO, Scopus, Web of Science databases until December 2021. Manual screening of issues in endodontic journals and references of relevant articles were assessed individually. The risk of bias (RoB) of the included articles was evaluated with the QUIN tool (Quality Assessment Tool for In Vitro Studies).

RESULTS

Among 1640 retrieved articles, 49 were included in the qualitative synthesis. Fifteen articles had low RoB, 33 articles had medium RoB, and only 1 study was at high RoB. Continuous rotary systems had better centering ability in both moderate and severe canal curvatures and resulted in less apical transportation in severely curved root canals. None of the kinematic systems was capable of instrumenting the entire canal surface area. Reciprocating kinematics systems tended to provide higher increase in surface area of severely curved canals and produced fewer dentinal microcracks in moderately curved canals.

CONCLUSIONS

The evidence presented in this review suggests that continuous rotary system seems to be better than reciprocating system in solving the major issues encountered during root canal instrumentation of extracted teeth with moderate and severe curvatures.

An In Vitro Comparative Assessment of Shaping Capacity of a Single-File System Over Multiple-File System in Root Canals

Objectives

The study's objective was to contrast the two distinct rotary file techniques used to shape mandibular first molars.

Materials and Methods

The investigation involved twenty recently removed mandibular molars. A digital single-lens reflex (DSLR) camera was placed in a fixed position, a muffle block was built, and images of each tooth's three cross sections were obtained. The specimens were split into the following two groups at random: Rotary files from WaveOne were used to prepare group A and Mtwo rotary files were used to prepare group B.

Results

At the coronal, middle, and apical thirds of the root canals, WaveOne file system demonstrated improved centering ability compared with the Mtwo file system (P 0.05).

Conclusion

When compared to the Mtwo file system, WaveOne file system demonstrated improved centering capabilities and needed significantly less time to build the curved canals.

Evaluation of shaping ability of different glide path instruments: a micro-computed tomography study

BACKGROUND

This study aimed to compare the shaping ability of different instruments, TruNatomy Glider (TRN-G), WaveOne Gold Glider (WOG-G), and ProGlider (Pro-G) using micro-computed tomography (micro-CT).

METHODS

The mesial canals of 27 mandibular molars with two separate mesial canals and moderate curvature were included in this study [n = 27 mesiobuccal (MB) and mesiolingual (ML) root canal]. According to the manufacturer's instructions, the glide path was created with TRN-G, WOG-G, and Pro-G glide path instruments (n = 9 MB and ML root canal in each group). Micro-CT scanning was performed before and after preparation. Mesiodistal (MD) and buccolingual (BL) transportation and the centering ratio were measured at three levels within the canal (3, 5 and 7 mm). A three-way robust ANOVA was used to compare the parameters.

RESULTS

TRN-G showed significantly greater transportation in the MD direction than the other instruments throughout the root canal (overall root canal) (p < 0.05). The best centering ability in the BL direction was shown by the WOG-G, regardless of level within the canal and canal distinction (MB vs. ML) (p < 0.05). There was no significant difference between groups according to the level within the canal and canal parameters (p > 0.05). Whether the root canal was MB or ML did not affect centering or transportation (p > 0.05).

CONCLUSIONS

Glide path instruments can be used to shape moderately curved canals with minimal apical transportation and better centering ability. All three tested glide path files can used safely before the shaping file.

Evaluation of Curved Canal Transportation Using the Neoniti Rotary System with Reciprocal Motion: A Comparative Study

The ideal root canal preparation is where the original canal morphology is maintained during the biomechanical preparation. Preparation of curved canals has always been a challenge to clinicians. Better results have been suggested for a single NiTi instrument with reciprocating motion than the conventional continuous rotation method in the preparation of curved root canals. Although the Neoniti rotary system is not suggested to be used with reciprocal motion, running a pilot study, we found that it could be possible. The present study aimed to investigate if shaping curved canals using the Neoniti rotary system with reciprocal motion leads to better results in terms of root canal transportation. One hundred acrylic j-shape canal simulator endoblocks were used in this study. Five preparation sequences were applied: GPS followed by A1#20 (GPS + A1#20), GPS followed by A1#20 and then A1#25 (GPS + A1#20 + A1#25), GPS followed by A1#25 (GPS + A1#25), hand file followed by A1#20 (hand file + A1#20), and GPS followed by A1#20 (with reciprocal motion) (GPS + A1#20(reciprocal)). Pictures were taken from blocks once before and once after preparation from two dimensions. Before-and-after pictures were superimposed in Photoshop software. Measurements were performed in Digimizer. The number of autoreverses and pecking motions was recorded after reviewing the recorded videos. Data were analyzed in SPSS, version 26. A p value of less than 0.05 was considered statistically significant. The group GPS + A1#20 + A1#25 had more transportation compared with the others, at apical, middle, and coronal thirds not only in the frontal view but also in the lateral view. Other groups were not significantly different. The number of peckings and autoreverses was significantly less when A1#25 was used after GPS and A1#20. When A1#20 was used with reciprocal motion, it had less peckings compared with the same file with continuous rotation, and no autoreverses were observed in that group. Using Neoniti files with reciprocal motion might result in less instrument fatigue and favorable results, with respect to canal anatomy preservation. Using A1#20 before A1#25 also will decrease the stress on the instrument during preparation. However, this may lead to significantly more canal transportation.

A Critical Review of Methods for Quantitative Evaluation of Root Canal Transportation

INTRODUCTION

A comparison between root canal transportation studies is nearly impossible because of nonstandardized transportation evaluation methods. The aim of the present review was to search, compare, and critically discuss transportation evaluation methods.

METHODS

A search of PubMed, Web of Science, Scopus, ScienceDirect, and reference lists of articles was conducted up to March 2020 using appropriate key words to identify transportation evaluation methods. The methods in the included articles were extracted, compared, and categorized.

RESULTS

Seventy-four articles using original methods were selected. All studies share 3 main steps: image acquisition, image measurements, and calculation of parameters. Images were acquired by photography, radiography, and computed tomographic imaging. Two types of measurements were used: the amount of removed material and the canal center point distance. The parameters were calculated and reported as distance or ratio. Relationships between the different transportation parameters were found and confirmed with mathematical simulation.

CONCLUSIONS

Although methods were proposed as being novel, similarities between them were found, enabling the classification of the methods and identifying correlations. The canal center point distance is the most suitable for the description of canal transportation because it is comprehensible and it relates to the mathematical concept of translation. Removed material-based measurements are double the value of the canal center point distance. Ratio parameters are not suitable for reporting transportation.

Micro-computed Evaluation of Canal Transportation and Centering Ability of 5 Rotary and Reciprocating Systems with Different Metallurgical Properties and Surface Treatments in Curved Root Canals

INTRODUCTION

The aim of this study was to evaluate the transportation and centering ability of 5 different rotary and reciprocating file systems with different metallurgical properties and surface treatments in curved root canals.

METHODS

Fifty mesiobuccal round canals of upper molars with a curvature of 25°-40° were assigned to 5 experimental groups (n = 12) according to the instrumentation system used: ProTaper Next (Dentsply Sirona, York, PA), Reciproc Blue (RCB [VDW, Munich, Germany]), Reciproc (VDW), TruNatomy (TRN [Dentsply Sirona]), and XP-endo Shaper (FKG, La Chaux-de-Fonds, Switzerland). During instrumentation, 5 mL 2.5% sodium hypochlorite was used in each root canal. The final irrigation protocol included 15% EDTA followed by sodium hypochlorite irrigation. The micro-computed tomographic scanning of the samples was performed before and after instrumentation to analyze the transportation and centering ability at 3 canal levels. The results were analyzed with the 1-way analysis of variance test with the corresponding post hoc test.

RESULTS

Overall, RCB caused significantly more canal transportation compared with the other techniques (P < .05). There were no significant differences between the other techniques (P > .05). ProTaper Next had a significantly better ability to stay within the central axis of the root canal compared with the Reciproc and RCB techniques (P = .046 and P = .017, respectively). In the apical third, all techniques caused similar apical transportation and centering ability (P > .05). In the middle and cervical parts of the canal, the RCB caused significantly greater canal transportation than the other techniques (P < .05).

CONCLUSIONS

Under the limitations of this study, all tested techniques had similar transportation and centering abilities in the apical part of the canal. However, the overall results and those in the middle and coronal parts of the canal indicated that reciprocating instruments resulted in more canal transportation and less centered preparations.

Effectiveness of Parameters in Quantifying Root Canal Morphology Change after Instrumentation with the Aid of a Microcomputed Tomography

The objective of this study was to analyse the effectiveness of some parameters which characterise the change in morphology in human root canals subjected to ProTaper rotary enlargement with the help of an X-ray microfocus computed tomography (MCT) and to introduce a novel parameter that is effective in quantifying changes in root canal morphology. Ten each straight and curved root canals with mature apices chosen from extracted human upper incisor and canine teeth were scanned with MCT before and after canal shaping using ProTaper rotary instruments in order to facilitate three-dimensional digital reconstruction and quantitative gauging of relevant instrumental parameters and changes therein (surface area and volume). Root canal geometry change and the effectiveness of shaping were quantified with Structure Model Index change (ΔSMI) and surface area change to volume change ratio (ΔSA/ΔV). These two parameters were also tested on simulated canals. Postinstrumentation cross-sectional changes were also analysed, but only on the plastic blocks. Statistical analysis of parameters was carried out to verify the significance of results. Analysis of cross-sectional shape of postinstrumented resin simulated canals showed statistically significant decrease in Form Factor (p<0.05) and statistically significant increase in Eccentricity (p<0.005). ΔSMI did not show significant difference between straight and curved canals. SMI values showed bidirectional change during root enlargement which questions the reliability of this metric in analysing instrumentation. Statistically significant (p<0.005) deviations in ΔSA/ΔV were quantified as 1.92 and 3.22 for straight and curved human canals, respectively. Instrumentation-induced canal geometry change was determined to be more pronounced in curved canals using the novel parameter ΔSA/ΔV. This has been proven as being a statistically accurate and reproducible parameter for quantitative characterisation of root canal geometry change and differentiation of preparational efficacy for both straight and curved root canals.