Efficacy of the ProTaper retreatment system in removing Thermafil, GuttaCore or vertically compacted gutta-percha from curved root canals assessed by micro-CT

Outcome of root canal retreatment filled with gutta-percha techniques: A systematic review and meta-analysis

OBJECTIVE

The present systematic review and meta-analysis aimed to evaluate the success rate of root canal retreatment filled with gutta-percha and the variables related to retreatment success.

DATA

The PRISMA guidelines were followed for the present review. The study protocol was registered in the International Prospective Database of Systematic Reviews (PROSPERO CRD42021283134). Risk assessment was performed using the Newcastle-Ottawa scale. Funnel plots were used to detect publication bias and asymmetry was assessed using Egger's tests.

SOURCES

PubMed, Scopus, ScienceDirect, Cochrane, and additional sources were searched.

STUDY SELECTION

Studies published until 10 December 2022. Clinical studies evaluating the success of root canal retreatment filled with gutta-percha with at least a 1-year follow-up were selected.

RESULTS

Ten studies and one unpublished study fulfilled the inclusion criteria for quantitative analysis. The success rate of non-surgical root canal retreatment was 71% (95% CI: 66%-76%) with strict criteria and 87% (79% - 93%) with loose criteria for 1-3 years of follow-up, and 77% (66% - 86%) with strict criteria for a 4-5 years of follow-up. Endodontically retreated teeth with periapical lesions had a lower success rate under strict criteria. The tooth type, dental arch, initial periapical index (PAI) score, and the number of visits also affected the treatment success rate under strict criteria. For the loose criteria, teeth with larger periapical lesions and higher initial PAI scores had a lower success rate.

CONCLUSIONS

According to the present systematic review and meta-analysis, non-surgical root canal retreatment results in favourable outcomes. The presence of a periapical radiolucency, periapical lesions >5mm, a higher initial PAI score, multiple-visit retreatments, and mandibular and molar teeth resulted in a lower success rate.

CLINICAL SIGNIFICANCE

Non-surgical root canal retreatment filled with gutta-percha techniques is a relatively predictable procedure with a high success rate. Several variables can affect retreatment success, mainly the presence and size of a periapical lesion and the type of tooth.

Removal of Thermafil obturators using two different techniques: A comparative Ex Vivo study

INTRODUCTION

The aim of this ex vivo study was to compare two techniques for removal of Thermafil obturators from curved root canals in mandibular molars.

METHODS

Sixty mesial root canals in extracted mandibular molars were distributed into matched pairs according to degree and radius of curvature and were prepared to size 35/.04 and obturated with Thermafil obturators size 35. Each tooth was embedded in resin, mounted in a mannequin head and isolated with rubber dam to simulate clinical conditions. Removal of obturators was undertaken under a dental operating microscope by an experienced endodontist using either the FragRemover loop device, or reciprocating NiTi instruments. Pre- and postoperative micro-CT scans were taken to compare the amount of remaining filling material and of removed dentin. Eventual problems during removal attempts were recorded.

RESULTS

Using Reciproc 24 carriers (80%) were removed, 16 in one piece, 8 in small pieces, in 6 cases removal failed. The FragRemover removed 12 carriers (40%), all of these completely, but in 18 cases removal failed (P < 0.05). Reciproc left less remaining filling material than the FragRemover (P < 0.05) but removed significantly more dentin in the apical part of the root canal (P < 0.01). There was no significant difference concerning the total amount of removed dentin (P > 0.05) between both groups. Seven complications occurred in the Reciproc group. In five teeth working length could not be reached, in two teeth a Reciproc file R25 fractured. With the FragRemover 64 complications occurred, in 36 cases, including second removal attempts, the loop slipped over the carrier, in 24 cases the top of the carrier was sheared off. In nine cases separation of the core occurred too far apically, not allowing further use of the FragRemover. In four cases the wire loop tore.

CONCLUSIONS

Reciproc was more effective in removal of Thermafil carriers, whereas using the FragRemover less dentin was removed in the apical part of the root canal and more obturation material was left.

Effectiveness and safety of rotary and reciprocating kinematics for retreatment of curved root canals: a systematic review of in vitro studies

Objectives

This systematic review (register-osf.io/wg7ba) compared the efficacy and safety of rotary and reciprocating kinematics in the removal of filling material from curved root canals.

Materials and Methods

Only in vitro studies evaluating both kinematics during retreatment were included. A systematic search (PubMed/MEDLINE, Scopus, and other databases, until January 2021), data extraction, and risk of bias analysis (Joanna Briggs Institute checklist) were performed. Efficacy in filling removal was the primary outcome.

Results

The search resulted in 2,795 studies, of which 15 were included. Efficacy was measured in terms of the remaining filling material and the time required for this. Nine studies evaluated filling material removal, of which 7 found no significant differences between rotary and reciprocating kinematics. Regarding the time for filling removal, 5 studies showed no difference between both kinematics, 2 studies showed faster results with rotary systems, and other 2 showed the opposite. No significant differences were found in apical transportation, centering ability, instrument failure, dentin removed and extruded debris. A low risk of bias was observed.

Conclusions

This review suggests that the choice of rotary or reciprocating kinematics does not influence the efficacy of filling removal from curved root canals. Further studies are needed to compare the kinematics safety in curved root canals.

Critical analysis of research methods and experimental models to study removal of root filling materials

Despite enjoying high favourable outcome rates, root canal treatment is not always successful. Root canal retreatment is a widely practised option for managing a non-healing root treated tooth. A basic distinction between retreatment and initial treatment is the requirement to remove the existing root filling material occupying the root canal space. Only then, can the technical deficiencies and possible causes of failure be addressed. Hence, the successful removal of the root filling material is critical to achieving the objectives of retreatment. Many different materials and techniques have been used for root canal filling, which have been documented in a plethora of studies; these are mainly laboratory studies investigating the removal of root filling materials. To help guide future research, which may then better inform clinical practice in relation to retreatment procedures, the focus of this narrative review is on the research methods and experimental models employed to study the removal of root filling materials. The current available literature demonstrates great variation in the research methodologies used to study the removal of root filling material, including direct visualization by splitting tooth samples or clearing, three-dimensional radiographic imaging including using microcomputed tomography or cone-beam computed tomography, and a combination of these techniques. Depending on the research method employed, variation also exists in quantification of root filling material removal; these include measurements of surface area, volume or weight, and criteria-based (semi-quantitative) assessment. Experimental models, using human teeth or resin models, differ with respect to standardization techniques and replication of the clinical scenario including initial sample preparation, canal filling, allocation and technical aspects of retreatment procedures. Future models should replicate, as closely as possible, the clinical scenario. Currently, microcomputed tomography provides a highly detailed, non-invasive and non-destructive method of objectively assessing and quantifying root filling removal.

Efficacy of Removing Thermafil and GuttaCore from Straight Root Canal Systems Using a Novel Non-Surgical Root Canal Re-Treatment System: A Micro-Computed Tomography Analysis

The present study aims to evaluate the effectiveness of an XP-endo non-surgical root canal re-treatment system in removing both GuttaCore and Thermafil gutta-percha carrier-based root canal filling materials from straight root canal systems using micro-computed tomography (micro-CT) analysis. The study was performed on 20 single-rooted upper teeth, which were randomly allocated into the following study groups: Group A, Thermafil and AH Plus sealer (n = 10); Group B, GuttaCore and AH Plus sealer (n = 10). Before and after the non-surgical root canal re-treatment procedure, the samples were submitted for a micro-CT analysis. The volume of the root canal filling material (mm³), the volume of the remaining root canal filling material (mm³) and the time (minutes) needed to remove the root canal filling material were also recorded. Student's t-test was used to analyze the results. No statistically significant differences were found between the volume of the remaining root canal filling material in the GuttaCore and Thermafil root canal filling systems at the coronal third (p = 0.782), middle third (p = 0.838) or apical third (p = 0.882) of the straight root canal systems; however, the GuttaCore required a statistically significant (p = 0.037) shorter amount of time (4.72 ± 0.76 min) to be removed than the Thermafil carrier-based root canal filling material (5.92 ± 1.42 min). The XP-endo Finisher non-surgical endodontic re-treatment system removes both GuttaCore and Thermafil gutta-percha carrier-based root canal filling materials from straight root canal systems, although removal of the GuttaCore gutta-percha carrier-based root canal filling material required less time.

A comparative study of dentinal tubule penetration and the retreatability of EndoSequence BC Sealer HiFlow, iRoot SP, and AH Plus with different obturation techniques

Objectives

This study aimed to evaluate dentinal tubule penetration and the retreatability of EndoSequence BC Sealer HiFlow (HiFlow), iRoot SP, and AH Plus when using the single-cone (SC) or continuous wave condensation (CWC) technique.

Materials and methods

Sixty-five single-rooted teeth were instrumented and randomly divided into 5 groups: group 1, AH Plus/CWC; group 2, iRoot SP/CWC; group 3, iRoot SP/SC; group 4, HiFlow/CWC; and group 5, HiFlow/SC. The ability to re-establish patency during endodontic retreatment was recorded, as was the time taken to reach the working length. Dentinal tubule penetration and remaining debris after retreatment were evaluated by confocal microscopy and scanning electron microscopy. Data were analyzed by Kruskal-Wallis test and Dunn’s multiple comparisons test (α = 0.05).

Results

The HiFlow/CWC and iRoot SP/CWC groups required more time to reach the working length than groups that underwent the SC technique regardless of the sealer used (P < .05). The HiFlow/CWC group showed a significantly higher percentage of sealer penetration area than that of the iRoot SP/SC at 4 mm from the apex (P < .05) and penetrated deeper into dentinal tubules than iRoot SP/SC at both 8-mm and 12-mm levels (P < .05). Moreover, the HiFlow/CWC and HiFlow/SC groups demonstrated less remaining sealer along the canal wall than AH Plus/CWC group at 4-mm level (P < .05).

Conclusions

HiFlow/CWC technique showed better performance in dentinal tubule penetration than that of iRoot SP/SC. Both HiFlow and iRoot SP combined with CWC technique groups required more retreatment time than the other groups. Furthermore, using HiFlow with either the CWC or SC technique left less remaining sealer at 4-mm level than using AH Plus with the CWC technique during retreatment.

Clinical relevance

With favorable performance in dentinal tubule penetration and retreatability in endodontic retreatment, the combined use of EndoSequence BC Sealer HiFlow with the recommended continuous wave condensation technique may be a worthwhile choice in root canal treatment.

In vitro comparative evaluation of efficiency of XP-endo shaper, XP-endo finisher, and XP-endo finisher-R files in terms of residual root filling material, preservation of root dentin, and time during retreatment procedures in oval canals - A cone-beam computed tomography analysis

Background:

In an oval-shaped canal, no single instrumentation systems were effective in absolute removing obturation.

Aim:

The aim of the study was to evaluate the performance of ProTaper Universal Retreatment (PTUR) system, XP-endo Shaper (XPS), XP-endo Finisher (XPF), and XP-endo Finisher-R (XPF-R) in removing root-canal filling material and preservation of sound dentin during retreatment procedure.

Methodology:

Root-canal preparation was performed on 60 mandibular premolars with oval-shaped canals using the ProTaper Gold file system. Preobturation scans were performed to measure canal volume of the canal and recorded. Obturation was performed and the samples were randomly assigned into four groups according to the retreatment protocol used (n = 15): H-file, PTUR files, PTUR followed by XPF file, and XPS supplemented with XPF-R file. After retreatment, the specimens were re-scanned and volumetric analysis of remaining root filling material, volume of the canal space were measured using EZ-3Di Software Version 5.0.0.2. All the data were subjected to one-way ANOVA and post hoc Tukey's test with a significance of 5%.

Results:

XPS + XPF-R showed promising results in the removal of obturating material and preservation of root dentin than any other group. The difference is statistically significant.

Conclusion:

XPS + XPF-R removed gutta-percha more significantly without sacrificing the sound dentin along with instrumentation.

Effect of different obturating techniques and sealers on the removal of filling materials during endodontic retreatment

Background:

Adequate removal of previous root filling materials is an important objective during endodontic retreatment.

Aim:

This study was aimed to evaluate the influence of obturation quality and sealer type on the removal of root filling materials during endodontic retreatment using micro-computed tomography (μ-CT).

Materials and Methods:

Ninety extracted mandibular premolars were randomly assigned to two groups (n = 45) based on the type of sealer (AH Plus and BioRoot RCS) and three sub-groups based on the obturating technique used, i.e., cold lateral condensation, warm vertical compaction, and thermoplasticized injectable techniques. Specimens were scanned using μ-CT before and after retreatment to assess the amount of filling material, and time taken for removal was recorded.

Statistical Analysis:

Data were analyzed using two-way analysis of variance and Tukey's multiple post hoc test at 5% significance level.

Results:

Filling debris percentage and retreatment time were not significantly affected by the type of sealer (P ≥ 0.05). The percentage of remaining filling material was higher in teeth obturated with thermoplasticized technique (P < 0.05). Significantly more filling material debris was observed in apical third (P < 0.05).

Conclusions:

The type of obturating technique used for initial root canal treatment has influenced the amount of remaining filling material and retreatment time. Retreatability of the BioRoot RCS sealer was similar to the AH Plus sealer.

The retreatment abilities of ProTaper Next and F6 Skytaper: a micro-computed tomography study

Purpose

The aim of this study was to evaluate the retreatment abilities of the ProTaper Next (PTN) and F6 SkyTaper (F6) systems by using micro-computed tomography (microct), radiographic and microscopic imaging techniques.

Materials and methods

The root canals of twenty-six extracted mandibular premolar teeth were prepared and obturated. For the retreatment procedure, the teeth were randomly divided into two equal groups according to endodontic instruments: PTN (X4) and F6 (#40/.06). Pre- and post-operative filling material volumes were measured with micro-ct, and areas were measured with radiographic and microscopic imaging techniques. The percentages of residual material were calculated, and then statistically compared. The significance level was set at p<0.05.

Results

There was no statistically significant difference between F6 and PTN for retreatment efficacy in the micro-ct and radiographic imaging techniques (p>0.05). PTN demonstrated better cleaning ability when evaluated by microscopic imaging. (p<0.05). The correlation was moderate between micro-ct and radiographic, and micro-ct and microscopic imaging groups; however, it was strong between radiographic and microscopic imaging methods.

Conclusion

The PTN and F6 files had similar effects in the removal of filling material with microct evaluation. The radiographic imaging method gave similar results with micro-ct imaging.

GuttaCore Pink, Thermafil and Warm Vertically compacted gutta-percha retreatment: Time required and quantitative evaluation by using ProTaper files

The goal of non-surgical treatment is to obtain an access to the root canal system in order to remove the previous filling. We analized 45 human single-canal roots, mesial roots of mandibular molars and distal roots of maxillary molars without previous endodontic treatment, fractures, resorptive defects or open apices. We evaluated the time required to retreat root canals obturated by a new generation of GuttaCore, GuttaCore Pink^®, compared to Thermafil^® and Warm Vertically compacted gutta-percha, by using ProTaper^® Retreatment and ProTaper^® Universal. Moreover, a quantitative analysis of residual filling material in the canal after retreating and shaping was performed. The Kruskal-Wallis and Dunn's test were used to determine significant differences. Our data show that the GuttaCore Pink^® can be removed from the root canal system in a lower amount of time compared to the Thermafil^®. Concerning the amount of residual filling material, there are no significant differences between the three groups.

Microscopic and Chemical Assessments of the Filling Ability in Oval-Shaped Root Canals Using Two Different Carrier-Based Filling Techniques

Objectives The aim of this study was to assess the filling ability in oval-shaped canals using two different carrier-based filling techniques.

Materials and Methods Twenty-four human mandibular premolars with one oval canal were selected. Canals were shaped using WaveOne Gold Primary and ProGlider. Samples were divided into two groups and filled as follows: Thermafil and GuttaCore. The proportions of gutta-percha-filled areas (GPFAs), sealer-filled areas (SFAs), and void areas (VA), at 2 and 5 mm, were analyzed using optical numeric microscope, scanning electron microscope, and energy-dispersive X-ray.

Statistical Analysis Data were compared by Kruskal–Wallis one-way analysis of variance on ranks, with statistical significance set at α = 0.05.

Results At 2 and 5 mm distances from the apex, this study discloses no statistically different filling ability for the two techniques. Concerning each sample treated using both filling systems, the presence of tags was visualized. At working length (WL)-5, and WL-2, the maximum tag penetration depth for the GuttaCore group into the dentinal tubules was, respectively, 96 μm and 48 μm, whereas the values in the thermafil group were 109 μm, and 55 μm, respectively.

Conclusions Our results clearly show that Thermafil and GuttaCore can fill oval-shaped canals in appropriate way. Furthermore, we can state that the GuttaCore obturator allows to preserve the same filling ability than Thermafil obturator, in view of the fact that there was no difference, in terms of GPFA, SFA, and VA between the two different carrier-based obturation techniques.

Atomic force microscopy and energy dispersive X-ray spectrophotometry analysis of reciprocating and continuous rotary nickel-titanium instruments following root canal retreatment

The aim was to examine the effect of retreatment process on the surface roughness and nickel titanium (NiTi) composition of ProTaper Universal Retreatment (PTUR; consists of 3 files; D1, D2, D3) and WaveOne Gold (WOG) (primary) instruments. Twenty extracted mandibular molar teeth with severe curved (30-40°) mesial roots were selected and divided into two groups (n = 10) based on the instrument used for the removal of the root canal filling. Before and after using the instruments in two canals, they were subjected to atomic force microscopy (AFM) and energy dispersive X-ray spectrophotometry (EDX) analysis. The EDX analysis data and roughness average (Ra) and root mean square (RMS) values were analyzed statistically using a one-way analysis of variance and post hoc Tukey's test at the 5% significant level. There was no significant difference between the new and used D1 and D2 PTUR and WOG instruments in terms of the Ni composition (p > .05). The Ti contents of the used D2 and D3 PTUR instruments were lower those of the new instruments (p < .05). In both new and used instruments, PTUR and WOG have no difference in terms of Ra and RMS values. (p > .05). The Ra and RMS values of the PTUR and WOG systems significantly increased after removal of the root canal filling (p < .05). The use of PTUR and WOG instruments for removal of root canal filling in severely curved root canals affected the surface topography of the files. The NiTi composition of the WOG instruments was unaffected by the retreatment process.

Role of Computed Tomography Scan in Dental Trauma: A Cross-Sectional Study

Background:

Dental trauma is caused by fracture(s) in the vertical plane and the horizontal plane of roots. The objective of this study is to perform multiple diagnostic modalities for the diagnosis of horizontal root fracture(s) of the tooth.

Methods:

A total of 250 patients with dental complaints were subjected to intraoral radiography, multidetector helical computed tomography (MDHCT), and limited cone beam computed tomography (LCBCT). The suspected tooth was extracted, visually inspected, and subjected to microcomputed tomography (micro-CT). Images were observed in the lightbox, and a fracture was considered if it had been directly visualized as radiolucent line traversing tooth root. Wilcoxon test/Tukey post hoc test was performed at 99% of confidence level.

Results:

With respect to visual inspection, for LCBCT, intraoral radiography, MDHCT, and micro-CT, sensitivities were 0.988, 0.972, 0.967, and 0.979; accuracies were 0.956, 0.785, 0.905, and 0.888; false-positive values were 5, 21, 12, and 11; and false-negative values were 3, 24, 3, and 11, respectively. The area of the image visible at one time was in the order of treatment without radiography < intraoral radiography < MDHCT < micro-CT < LCBCT.

Conclusion:

The LCBCT had the highest sensitivity and accuracy for diagnosis of horizontal tooth root fracture(s).

Level of Evidence:

I.

Trial Registry:

researchregistry3647, dated December 31, 2016 (www.researchregistry.com).

Comparison of the effectiveness of various rotary and reciprocating systems with different surface treatments to remove gutta-percha and an epoxy resin-based sealer from straight root canals

AIM

To compare the Reciproc Blue, Reciproc and ProTaper Universal Retreatment systems with regard to the effective removal of epoxy resin-based sealer and gutta-percha during the retreatment of oval, straight root canals.

METHODOLOGY

Forty-five extracted, human mandibular first premolars with single straight oval canals were selected on the basis of cone beam computed tomography evaluations. The root canals were instrumented with the ProTaper Next system up to the X2 file, and filled with gutta-percha and epoxy resin-based sealer using the cold lateral condensation technique. After 1 month, the samples were randomly divided into three groups (n = 15) according to the retreatment system used: Reciproc Blue R40, Reciproc R40 and ProTaper Universal. The specimens were scanned at the resolution of 1.2 μm by a microcomputed tomography device after the root filling and retreatment procedures, and the decrease in the volume of filling material after each retreatment protocol was measured. The results were analysed using the Kruskal-Wallis test and additional box-and-whisker plots.

RESULTS

Although the volume of the filling material decreased significantly in all three groups (P < 0.05), none of the systems removed the material completely. The Reciproc system removed significantly more material than the ProTaper Universal (P < 0.001) and Reciproc Blue (P = 0.005) systems, with the latter two exhibiting equal volumes of remaining material (P = 0.068).

CONCLUSION

The Reciproc system was more effective than the Reciproc Blue and ProTaper Universal Retreatment systems during the removal of filling material from oval, straight canals, although none of the systems completely removed the filling material.