In vitro evaluation of filling material removal and apical debris extrusion after retreatment using Reciproc blue, Hyflex EDM and ProTaper retreatment files

OBJECTIVES

To evaluate the amount of remaining filing material and apical debris extrusion after retreatment using Reciproc Blue, Hyflex EDM and ProTaper Retreatment Files.

MATERIALS AND METHODS

Thirty-six extracted permanent mandibular first molars with moderately curved mesial roots were selected. Mesiobuccal canals were prepared using the ProTaper Next system up to size X2 and filled using gutta-percha and Adseal sealer via cold lateral compaction. Teeth were randomly divided into three equal groups (n = 12): Group 1: Reciproc Blue (RB)(VDW, Germany), Group 2: Hyflex EDM (HEDM)(Coltene/Whaledent, Switzerland), Group 3: ProTaper Universal Retreatment file system + ProTaper Next file system (PTUR + PTN)( Dentsply Maillefer, Switzerland). Eppendorf tubes were used to collect the apically extruded debris. Cone-beam computed tomographic scans were taken prior to and after retreatment and the volume of remaining filling material was assessed at the coronal, middle and apical levels. Statistical analysis was performed using the Kruskal-Wallis test, Friedman's test and Wilcoxon Sign Rank test. Significance level was set at p value 0.05.

RESULTS

There were no statistically significant differences among the three groups in the reduction of the volume of the filling material or in the amount of apically extruded debris.

CONCLUSION

All the tested filing systems showed similar efficacy in removing the filling material, however, none of them could achieve its complete removal. Apical extrusion of debris occurred with all the systems used with no significant difference between the three groups.

Present status and future directions - irrigants and irrigation methods

Irrigation is considered the primary means of cleaning and disinfection of the root canal system. The purpose of this review was to set the framework for the obstacles that irrigation needs to overcome, to critically appraise currently used irrigants and irrigation methods, to highlight knowledge gaps and methodological limitations in the available studies and to provide directions for future developments. Organization of bacteria in biofilms located in anatomic intricacies of the root canal system and the difficulty to eliminate them is the main challenge for irrigants. Sodium hypochlorite remains the primary irrigant of choice, but it needs to be supplemented by a chelator. Delivery of the irrigants using a syringe and needle and activation by an ultrasonic file are the most popular irrigation methods. There is no evidence that any adjunct irrigation method, including ultrasonic activation, can improve the long‐term outcome of root canal treatment beyond what can be achieved by instrumentation and syringe irrigation. It is necessary to redefine the research priorities in this field and investigate in greater depth the penetration of the irrigants, their effect on the biofilm and the long‐term treatment outcome. New studies must also focus on clinically relevant comparisons, avoid methodological flaws and have sufficiently large sample sizes to reach reliable conclusions. Future multidisciplinary efforts combining the knowledge from basic sciences such as Chemistry, Microbiology and Fluid Dynamics may lead to more effective antimicrobials and improved activation methods to bring them closer to the residual biofilm in the root canal system.

A critical analysis of research methods and experimental models to study irrigants and irrigation systems

Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro-omputed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics.

Apical Extrusion of Debris during Root Canal Preparation with ProTaper Next, WaveOne Gold and Twisted Files

(1) Background: Apical extrusion of debris is an example of a complication that may arise during root canal treatment, and it has been proven to be an unavoidable occurrence during endodontic treatment by numerous authors. Even though it may not hinder the long-term outcome of treatment, it may lead directly to increased levels of postoperative pain and, therefore, lower levels of patient acceptance and satisfaction. The aim of the study was to assess the weight of apically extruded debris during root canal preparation with instruments that use different movement kinematics (rotary, reciprocating, and adaptive motion); (2) Methods: The study was performed using the Myers and Montgomery model. Sixty human premolar teeth were inserted into preweighed Eppendorf tubes and randomly classified into three groups. After manual glide-path preparation, teeth in each group were instrumented to working length set 1 mm short of the anatomical apex using the standard sequence provided by the manufacturers (for Group 1: ProTaper Next X1 & X2; for Group 2: WaveOne Gold Primary, for Group 3: Twisted Files SM1-SM3). Root canals were irrigated with 1 mL of 0.9% NaCl solution between each file insertion. The tubes with collected debris were stored in an incubator at 70 °C for 5 days in order to evaporate the liquid component. Measurement of the weight of extruded debris was performed by subtracting the preinstrumentation from the postinstrumentation weight of the tubes. The results were analyzed with Kruskal-Wallis ANOVA, with significance level set at 0.05; (3) Results: The weight of extruded debris was 0.337 mg (SD = 0.148) for Group 1, 0.305 mg (SD = 0.201) for Group 2, and 0.348 mg (SD = 0.135) for Group 3. (4) Conclusions: Engine-driven root canal preparation with the use of instruments ProTaper Next, WaveOne Gold and Twisted Files that use different movement kinematics (rotary, reciprocating, and adaptive motion) was associated with apical extrusion of debris to a similar extent.

PRIASE 2021 guidelines for reporting animal studies in Endodontology: explanation and elaboration

Laws and ethics require that before conducting human clinical trials, a new material, device or drug may have to undergo testing in animals in order to minimize health risks to humans, unless suitable supporting grandfather data already exist. The Preferred Reporting Items for Animal Studies in Endodontology (PRIASE) 2021 guidelines were developed exclusively for the specialty of Endodontology by integrating and adapting the ARRIVE (Animals in Research: Reporting In Vivo Experiments) guidelines and the Clinical and Laboratory Images in Publications (CLIP) principles using a validated consensus-based methodology. Implementation of the PRIASE 2021 guidelines will reduce potential sources of bias and thus improve the quality, accuracy, reproducibility, completeness and transparency of reports describing animal studies in Endodontology. The PRIASE 2021 guidelines consist of a checklist with 11 domains and 43 individual items and a flowchart. The aim of the current document is to provide an explanation for each item in the PRIASE 2021 checklist and flowchart and is supplemented with examples from the literature in order for readers to understand their significance and to provide usage guidance. A link to the PRIASE 2021 explanation and elaboration document and PRIASE 2021 checklist and flowchart is available on the Preferred Reporting Items for study Designs in Endodontology (PRIDE) website (http://pride-endodonticguidelines.org/priase/).

Debris extrusion during root canal preparation with nickel-titanium instruments using liquid and gel formulations of sodium hypochlorite in vitro

This study compared the amount of apically extruded debris during root canal preparation with three single-file systems using liquid and gel-based formulations of sodium hypochlorite (NaOCl) or distilled water. Seventy-two single-canalled roots were divided into three groups: HyFlex EDM (Coltene-Whaledent); Reciproc Blue (VDW); and F-One Blue (Shanghai Fanta) and then divided into three subgroups: NaOCl liquid (Imicrly), NaOCl gel (Cerkamed Medical) and distilled water. The amount of extruded debris was calculated by determining the dry weight of the debris collected. Data were analysed using Kruskal-Wallis test with Bonferroni correction. Debris extrusion occurred in all subgroups. Both the instrument and the irrigant had an impact. The F-One Blue tended to extrude the least debris, though no significant difference was observed in the pairwise comparisons between instruments. NaOCl liquid resulted in significantly more extruded debris than NaOCl gel or distilled water. The results lead us to conclude that the NaOCl gel reduced debris extrusion compared to NaOCl liquid.