Methods of filling root canals: principles and practices

Obturation of Simulated Internal Resorption Cavities With Four Different Techniques and a Hydraulic Root Canal Sealer: A Comparative Stereomicroscopic Evaluation

Aim To compare the quality of obturation using WVC (warm vertical compaction), CLC (cold lateral compaction), injectable (iFill), and Thermafil (GuttaCore) techniques, along with hydraulic condensation of bioceramic (BC) sealer, and evaluating the percentage of gutta-percha (GP), sealer, and voids in simulated internal resorptive lesions, using an advanced stereomicroscope with ImageJ software (National Institutes of Health, Bethesda, MD, USA). Methods and material In this study, 40 freshly extracted maxillary incisors were collected, and endodontic instrumentation was done to working length using hand K-files. Simulated internal resorption cavities were created in the middle-apical third of the roots after horizontal sectioning and were re-cemented. The root canals were obturated using four techniques: WVC, CLC, iFill, and Thermafil, along with BC sealer. After one week, the samples were resectioned, the surfaces were photographed, and the percentage of GP, sealer, and voids in resorptive cavities was calculated using an advanced stereomicroscope and ImageJ software, respectively. The data were statistically analyzed using one-way analysis of variance (ANOVA) and post-hoc Tukey tests. Results The iFill approach had the highest total filled area in the simulated resorptive region (96%), followed by WVC (92%), CLC (91%), and GuttaCore (77%). CLC had a notably high percentage of sealers (46%), compared to WVC (40%) and Thermacore (41%). With 23% of voids, the GuttaCore technique was considered the least successful. Conclusions Warm GP condensation techniques, combined with hydraulic sealer in filling artificial resorption cavities, outperformed the other obturation procedures.

Comparative assessment of vertical fracture resistance in endodontically treated roots with different obturating systems and techniques: a systematic review and network meta-analysis of in vitro studies

BACKGROUND

This study conducted a thorough assessment of vertical root fracture (VRF) resistance of endodontically treated teeth filled with various canal-filling systems and techniques through frequentist network meta-analysis (NMA).

METHODS

A systematic literature search was performed to retrieve relevant publications using PubMed, Embase, ScienceDirect, Web of Science, and Cochrane Library databases. The retrieval time range was from Jan 2000 to Sep 2023. The literature selection and data extraction were independently conducted by two investigators. Eligible studies were critically appraised for risk of bias and quality of evidence. Subsequently, we used the 'network' package in Stata/MP 17.0 software to compare the VRF resistance of roots treated with different obturating systems or techniques.

RESULTS

Forty-eight trials involving 2724 single-canal roots were included in the NMA. The surface under the cumulative ranking curves indicated that Resilon/Epiphany (80.8%), although outdated, provided the highest VRF resistance among all obturating systems. This was followed by GP/iRootSP (55.5%), GP/MTA-Plus (47.9%), GP/AH-Plus (47.4%), GP/AH-26 (45.9%), and GP/ZOE (12.3%). The roots filled with Resilon/Epiphany showed better VRF resistance as compared to those filled with gutta-percha/AH-Plus (SMD = 0.77, 95%CI 0.10 to 1.45) and gutta-percha/zinc oxide eugenol (SMD = 1.64, 95%CI 0.47 to 2.80). The single cone technique (SCT) group displayed the highest VRF resistance, and roots filled with all techniques, except Thermafil, outperformed the positive control group.

CONCLUSIONS

Resilon/Epiphany demonstrated the greatest root strength among all six obturating systems, followed by GP/iRootSP and GP/MTA-Plus, which are calcium silicate-based systems. In contrast, the gutta-percha/zinc-oxide eugenol system exhibited the weakest performance. All canal-filling techniques, particularly the SCT, strengthen endodontically treated roots, except for the Thermafil technique. Further well-designed clinical trials with large sample sizes are essential for validation.

A multi-national survey-based evaluation of undergraduate/predoctoral endodontic education

AIM

To evaluate the current status of endodontic education and assessment at an undergraduate/predoctoral level in dental schools worldwide.

METHODOLOGY

The current survey comprised a 50-item online questionnaire related to undergraduate endodontic education. The project leaders emailed the survey's details to faculty members responsible for endodontic teaching at one dental school in every country to seek their willingness to participate in the survey. After the faculty members accepted, the survey details were sent to participants along with the survey link. Simple descriptive statistics were used to represent the data.

RESULTS

Amongst the 44 faculty members from different countries who agreed to participate, 36 completed the survey. Endodontic training starts in 50% of dental schools from the third year of the curriculum. Each dental school employs a diverse range of educational methods. During pre-clinical training, 19.4% of the participating dental schools used only natural teeth. Stainless-steel hand instruments, syringe irrigation with a needle, resin-based sealer and the cold lateral compaction technique are the most frequently used in pre-clinical and clinical training. A significant percentage of dental institutions necessitate that students treat a predetermined quantity of canals or teeth throughout their pre-clinical and clinical education. Dental institutions conduct formative, summative or a combination of the formative and summative throughout the clinical and pre-clinical phases of endodontic training.

CONCLUSIONS

According to the data collected from this survey, there are considerable variations in the curriculum for undergraduate/predoctoral endodontic programmes amongst the surveyed dental schools. Pre-clinical and clinical education should integrate a larger array of modern tools and procedures.

Three-dimensional assessment of obturation volume in lateral canals after three obturation techniques with bioceramic sealer: an in vitro comparative study

OBJECTIVE

This study aimed to evaluate the obturation ability of simulated lateral canal in mandibular premolars at three levels (3, 5, and 7 mm) from the apex using gutta-percha and BC Sealer HiFlow (BCHiF) with different obturation techniques, including continuous wave compaction (CWC), cold lateral condensation (CLC), and single cone (SC) techniques, by a 3D assessment method of the obturation volume with cone beam computed tomography (CBCT) and MIMICS software analysis.

METHODS

Thirty intact human mandibular premolars were decoronated, instrumented up to #30 taper 4%, and uniformly irrigated with 5.25% NaOCl and 17% EDTA. Six simulated lateral canals (3 pairs) were prepared at 3, 5, and 7 mm from the apex in each root, using #10 modified C-file. CBCT images were obtained, and lateral canal volumes were calculated using MIMICS software. The samples were divided into three groups: CWC (n = 10), CLC (n = 10), and SC (n = 10). All groups were obturated with BCHiF and gutta-percha. Another CBCT image was taken post-obturation, and 3D lateral canal obturation volume percentages were calculated using MIMICS software. Data were analyzed using SPSS software with One-way ANOVA and Sidak tests (α = 0.05).

RESULTS

Significant differences were observed in the 3D lateral canal obturation volume percentage at all three levels (P < 0.05). Both CWC and CLC techniques demonstrated higher 3D lateral canal obturation volume percentages (x ¯  = 89.64% andx ¯   =  73.28%; respectively) compared to the SC group)x ¯   =  43.10%).

CONCLUSION

BCHiF combined with the CWC technique has a higher ability to achieve preferable 3D obturation volume in the simulated lateral canal at 3, 5, and 7 mm.

CLINICAL RELEVANCE

In cases requiring endodontic treatment with lateral canals, the CWC obturation technique using BCHiF with gutta-percha may offer better outcomes compared to other obturation techniques.

Clinical and Radiographic Failure of Nonsurgical Endodontic Treatment and Retreatment Using Single-cone Technique With Calcium Silicate-based Sealers: A Systematic Review and Meta-analysis

INTRODUCTION

This systematic review and meta-analysis aimed to evaluate the clinical and radiographic failure of nonsurgical endodontic treatment and retreatment for mature permanent teeth with or without apical periodontitis using the single-cone (SC) obturation technique with calcium silicate-based bio-ceramic (CSBC) sealers and to compare these failure rates to other sealer materials and obturation techniques.

METHODS

A comprehensive search was conducted using MEDLINE (PubMed), Embase, Cochrane Library, Scopus, Web of Science, and gray literature up to March 2023. Two reviewers assessed the eligibility of the included studies. Eligible studies were critically appraised for risk of bias and quality of evidence. Subsequently, a meta-analysis of pooled data was conducted utilizing the RevMan software (P < .05) to evaluate the failure rate of non-surgical root canal therapy using CSBC sealers and SC obturation procedures. Separately, another analysis was conducted to compare those results with the outcome of nonsurgical root canal therapy using alternative obturation materials and methods.

RESULTS

Five studies were included. The pooled failure rate for nonsurgical endodontic treatment and retreatment combined using CSBC sealers and SC obturation technique was 6.8% [95% confidence interval (CI) = (3%-12%), I2 = 46%]. A second analysis was conducted on the 3 included clinical trials to compare the outcomes of the intervention (CSBC sealers and SC obturation technique) and control groups (other sealers and other obturation techniques). This analysis found no significant difference between the 2 groups regarding clinical and radiographic failure of endodontic treatment and retreatment [Risk ratio = 0.71, 95% CI = (0.33, 1.51), I2 = 0]. This difference was also not statistically significant when the failure rate of primary root canal treatment and retreatment were separately analyzed [Combined Risk ratio of primary root canal treatment = 0.94, 95% CI = (0.46, 1.93), I2 = 0%; Combined Risk ratio of retreatment = 0.21, 95% CI = (0.001, 75.46), I2 = 0%].

CONCLUSIONS

The overall results of this systematic review and meta-analysis demonstrate that the SC obturation technique with CSBC sealer provides similar results compared to other obturation materials and techniques in facilitating the healing of apical periodontitis.

Challenges Faced in Treating Maxillary Second Premolars With Three Canals: A Case Report

The maxillary second premolar has long been regarded as a tooth with a straight root canal anatomy, typically featuring a single root with two canals. However, emerging evidence suggests this tooth may harbor a more intricate internal morphology, challenging conventional perceptions, and treatment approaches. One such variation is three root canals within the upper second premolar, which has been gaining increasing attention in endodontic literature. Root canal treatment of maxillary second premolars with three canals demands meticulous debridement, shaping, and disinfection. A combination of magnification, illumination, and appropriate instrumentation aids in locating, negotiating, and cleaning the accessory canals effectively. Thorough cleaning of accessory canals can be achieved through effective irrigation solutions such as sodium hypochlorite, ethylenediaminetetraacetic (EDTA), and chlorhexidine, which help dissolve organic tissues and remove debris. Techniques like ultrasonic and sonic activation, as well as negative pressure irrigation systems, enhance the penetration and effectiveness of these irrigants. Additionally, the use of modern nickel-titanium rotary files, ultrasonic irrigation, and supplementary chelating agents enhances the management of complex canal configurations.

Assessment of dental students' knowledge and performance of master gutta-percha cone selection and fitting during root canal treatment: a pilot study

BACKGROUND

Misconceptions should be detected early in dental students' training to improve their clinical performance. Accordingly, this study aimed to assess undergraduate dental students' knowledge and performance of master gutta-percha (GP) cone selection and fitting during clinical endodontic courses at the College of Dentistry, King Saud University.

METHODS

Ninety-nine undergraduate dental students completed an online survey about their knowledge of master GP cone selection. Forty-five of these students were observed by faculty members in clinical endodontic courses while they fitted master GP cones during root canal treatments. The observers recorded the details of each student's cone-fitting techniques. The data were analysed using t-tests, one-way analysis of variance, and chi-square tests (p < 0.05). Inter- and intra-observer reliability were tested using Fliess' Kappa.

RESULTS SURVEY

All participants had good knowledge of over-extended cone management, while 80.8% knew how to properly manage a short cone. The proper flaring assessment method was selected by 86.9% of the female and 34.2% of the male students, and this difference was statistically significant (p = 0.0001).

OBSERVATION

The students labelled the working length on the master GP cone with an indentation in 64.4% of the cases and by bending the cone 35.6% of the time. Of all students, 84.4% encountered an apical stop, and this rate correlated significantly with the length of the cone on the master apical cone radiograph (p = 0.001). Improper shaping of the canal was the most common cause of ill-fitting cones (83.3%), while 16.7% of the students chose the wrong cone size. The final obturation length was adequate in 80% of the cases; 57.8% of the students were helped by instructors.

CONCLUSIONS

Most students had the basic knowledge required to solve problems related to the selection of master GP cones. However, in the clinical setting, more than half of the students required the assistance of an instructor to adjust their cone's fit. The presence of an apical stop had the most significant effect on the length of the fitted master GP cone on radiography. The most common cause of ill-fitting master cones was improper shaping of the canal.

Advanced Materials for Clinical Endodontic Applications: Current Status and Future Directions

Endodontics has significantly evolved in recent years, with advancements in instruments, biomaterials and nanomaterials science playing a pivotal role [...].

Comparison of Apical Sealing Capacity of ActiV GP/Glass Ionomer Sealer Versus Resilon/RealSeal and Gutta Percha/AH plus Sealers

BACKGROUND

In recent years, concerns have arisen regarding the sealing efficacy of traditional root canal obturation materials such as gutta-percha (GP) and various sealers. The resin-based obturation complexes like RealSealTM (SybronEndo, Orange, CA) and ResilonTM (Resilon Research LLC, Madison, CT) had been developed as replacements for conventional obturation materials, gutta-percha, and various types of sealers. Additionally, ActiV GPTM (Brasseler USA, Savannah, GA), a glass-ionomer-based obturation system, has gained attention.

AIM

This in vitro study's objective was to evaluate ActiV GPTM/GI (glass ionomer) sealer's sealing capacity and compare it to that of ResilonTM/RealSeal TM as well as gutta-percha/AH PlusTM (Dentsply International Inc, York, PA) taken as a control.

METHODS AND MATERIALS

In this in vitro investigation, 90 freshly excised single-rooted human premolars of the mandible were chosen. According to the substance used to seal the root canals, the teeth were randomly separated into three separate groups (n=30). Group 1: The ActiV GPTM obturation system was used to seal and obturate the canals. Group 2: ResilonTM/RealSealTM was used to obturate and block the canals. Group 3: GP points and AH PlusTM were used to seal the canals employing the lateral condensation methodology. All of the root surfaces-aside from the last 2 mm of the root-were painted with two coats of nail polish before being submerged in 2% methylene blue for a duration of 24 hours at a temperature of 37°C. The highest amount of dye leakage was determined using a stereomicroscope at 20X magnification.

RESULTS

The extent of dye penetration at the apical region in specimens of the ActiV GPTM category was 4.93±1.48 mm. The depth of dye penetration at the apical region in specimens of the ResilonTM category was 2.78 ±1.62 mm. The extension of penetration of dye was 0.48± 0.46 mm in specimens of the GP/AH PlusTM category. The degree of microlikeage was maximum in ActiV GPTM specimens and it was minimum in GP/AH PlusTM specimens. The microlikeage in specimens of the Resilon category was greater than GP/AH plusTM while it was lower than ActiV GPTM specimens. The observations were statistically meaningful (p<0.001).

CONCLUSION

Based on the results of the dye penetration examination, it can be concluded that the root canal wall sealing capabilities of ActiV GPTM with GI Sealer were inferior to those of GP/AH PlusTM and ResilonTM with RealSealTM.

Endodontic Outcome of Root Canal Treatment Using Different Obturation Techniques: A Clinical Study

OBJECTIVE

To evaluate the clinical outcome of root canal treatment by obturation technique, root canal filling quality, and tooth- and patient-related variables.

METHODS

This clinical study investigated the endodontic outcome of 114 teeth treated between the years 2009 and 2012. Three different obturation methods were used: (1) adhesive obturation using the continuous wave of condensation technique with Resilon® (CWR), (2) matching-taper single-cone technique with gutta-percha and AH Plus® (SCGP), and (3) matching-taper single-cone technique with gutta-percha and GuttaFlow® (SCGF). Pre- and postoperative periapical radiographs were performed to detect the presence of endodontic lesions (PAI classification) and to assess the quality of both the obturation and the restoration. Tooth- and patient-related data were collected.

RESULTS

The overall endodontic success rate was 75.4% after a mean observation period of 6.3 years. There were no significant correlations between the type or overall quality of obturation and the treatment outcome. Teeth with preoperative lesions had the highest odds ratio (factor of 4.98) for endodontic failure. Tooth- and patient-related variables had no significant effect on endodontic outcome.

CONCLUSIONS

The preoperative periapical status of teeth requiring endodontic treatment was a substantial prognostic factor for endodontic outcome, whereas the type of obturation material or technique did not affect it.

Inflammatory response to epoxy resin and calcium silicate sealers preheated with different temperatures: an in vivo study

OBJECTIVE

To determine the impact of heat exposure of different sealers on inflammatory cytokine secretions and tissue response in vivo.

MATERIALS AND METHODS

Silicone tubes were prefilled with epoxy resin (ER) or calcium silicate (CS) sealers, preheated at 37, 60, or 120 °C, and implanted in rat subcutaneous site. Peri-implant exudate and tissue were analyzed after 1 and 4 weeks for cytokine secretions and tissue organization.

RESULTS

At 1 week, 120 °C-preheated CS and ER induced higher secretions of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6), respectively, as compared to sham/empty tube groups. At 4 weeks, whereas TNF-α secretion was reduced in CS, it increased in ER group, particularly for 120 °C. Both sealers revealed high IL-6 after 4 weeks as compared to sham/empty tube, and generally, higher IL-6 secretions were associated with ER. Histology at 1 week revealed lower degree of inflammatory infiltrate in the groups of the highest preheating temperature (120 °C). Nonetheless, at 4 weeks, whereas fibrous capsule area and inflammatory infiltrate remained low in the CS120 group, they were high in ER120.

CONCLUSION

Preheating ER sealer to 120 °C induced high and prolonged secretion of proinflammatory cytokines (TNF-α and IL-6), whereas this effect was transient for the CS sealer. This was associated with increased fibrous capsule and inflammatory infiltrate in response to 120 °C-preheated ER.

CLINICAL RELEVANCE

Heat-induced changes in sealer properties alter the inflammatory response in vivo, which may affect the clinical outcome. This will not only help appropriate selection of obturation technique for different sealers, but also for optimizing the properties of new generation of sealers.

Single Cone Obturation versus Cold Lateral Compaction Techniques with Bioceramic and Resin Sealers: Quality of Obturation and Push-Out Bond Strength

Objectives

This study compared the obturation quality and push-out bond strength of single cone obturation (SCO) and cold lateral compaction (CLC) with AH-Plus and Sure Seal Root (SSR).

Materials and Methods

This in vitro experimental study was conducted on 88 single-rootedsingle-canal teeth with straight roots that were randomly divided into four groups (n = 22). All teeth were decoronated and underwent cleaning and shaping. Obturation was performed with AH-Plus and SCO technique in group 1 (SAH), AH-Plus and CLC technique in group 2 (LAH), SSR and SCO technique in group 3 (SS), and SSR and CLC technique in group 4 (LS). The roots were then sectioned into 3-mm thick slices and underwent digital photography at x25 magnification to assess the quality of obturation in the coronal, middle, and apical thirds by Image J software. The PBS was measured by a universal testing machine. The mode of failure was also determined under a stereomicroscope.

Results

The PBS was significantly higher in the LSS group than LAH and SAH groups, and also in the SSS group than the SAH group in all sections. The PBS in the LSS group was significantly higher than SSS in the coronal and middle thirds. Voids were significantly lower in LAH than in the SAH group in all sections. In LSS, voids in the coronal third were significantly lower than in LAH. In the middle third, voids in SSS were significantly lower than in SAH. The groups had no significant difference in the mode of failure (P > 0.05). The mean percentage of gutta-percha in the use of AH-Plus sealer was significantly higher than SSR (P < 0.05). The mean percentage of gutta-percha in the coronal third was lower than that in the middle and apical thirds (P < 0.05).

Conclusion

SSR showed higher PBS and less voids than AH-Plus. High PBS of the CLC/SSR group showed that CLC should still be preferred to SCO, and in the case of using SCO, SSR should be preferred to AH-Plus.

Evaluation of Different Root Canal Obturation Techniques in Internal Root Resorption of Three-Dimensional Printed Teeth Manufactured Using Computer Software

The objective of this study was to evaluate and compare the filling ability of various root canal obturation techniques on the internal root resorption (IRR) cavities of replicated tooth samples manufactured using computer software and a three-dimensional (3D) printer. Orthographic images and root structures of a healthy upper maxilla central incisor in determined volumes and sizes were drawn as a prototype with the aid of computer software. Using the same software, an IRR defect was also modeled. These two images were then transferred to the AutoDesk Fusion 360 3D modeling program (AutoDesk, San Rafael, CA) for meshing. Afterward, the tooth model was transferred to a 3D modeling and prototyping program (RhinoCeros 3D; Robert McNells & Assoc., New York) and printed on a 3D printer. Eighty replicas with IRR were manufactured and divided into four groups (n = 20 per group) according to the obturating techniques as follows: Group 1: Cold lateral compaction (CLC), Group 2: Core Carrier System (GuttaCore), Group 3: Injectable Cold Filling (GuttaFlow® BioSeal), and Group 4: Continuous Wave Obturation System (Elements Free). After root canal filling, replicas were scanned with a high-resolution micro-computed tomography system (SkyScan 1172; Bruker-microCT, Kontich, Belgium), data regarding voids (unobturated areas) inside the IRR defects were statistically analyzed using nonparametric Kruskal-Wallis tests. A pairwise comparison between the tested groups showed that Groups 3 and 4 had significantly fewer voids compared with Groups 1 and 2 in IRR defects (p < 0.05). Group 1/Group 2 and Group 3/Group 4 had similar results in terms of voids and there were no statistically significant differences (p > 0.05). The injectable cold filling system (GuttaFlow BioSeal) and the injectable continuous wave obturation system (Elements Free) successfully obturated the pathological IRR irregularities when compared with CLC and core carrier (GuttaCore) systems.

Penetration of Three Endodontic Sealers in Simulated Lateral Canals during the Lateral Condensation Technique: An In Vitro Study

Objective

This study aimed to compare the penetration depths of AH Plus, BioRoot RCS, and GuttaFlow 2 into simulated lateral canals when used with the cold gutta-percha lateral compaction technique.

Materials and Methods

Twelve resin training blocks (4 canals perch each resin block) were used. Each primary artificial canal had two lateral canals (apical and coronal). The main canals were instrumented with WaveOne Gold and irrigated with distilled water. The resin blocks were divided into three groups (N = 4 each/16 artificial canals), according to the type of root canal sealer; Group I: AH Plus, Group II: BioRoot RCS, and Group III: GuttaFlow 2. All canals were obturated with the cold lateral condensation technique. The linear extension of each endodontic sealer into the apical and coronal lateral canals was measured using a digital stereomicroscope and measuring software. Data were statistically analyzed using a one-way analysis of variance. The percentages of filling of the lateral canals were calculated and statistically compared using the Mann–Whitney test.

Results

The experimental sealers exhibited variable penetration depths into the lateral canals. All sealers showed significantly better penetration ability into the apical lateral canals than the coronal lateral canals (P < 0.05). AH Plus (3.184 ± 0.012 mm/99.5%) and GuttaFlow 2 (3.176 ± 0.017 mm/99.25%) were significantly better than BioRoot RCS (3.096 ± 0.026 mm/96.75%) in filling the apical lateral canals (P < 0.05). BioRoot RCS was the best sealer to fill coronal lateral canals (3.322 ± 0.085 mm/83.05%).

Conclusion

During the lateral condensation technique, the filling of the lateral canals is affected by the type of root canal sealer and the location of the lateral canals All the sealers tested have a good ability to fill the apical lateral, while BioRoot RCS was effective in filling both the coronal and apical lateral canals.

Influence of the root canal filling technique on the success rate of primary endodontic treatments: a systematic review

Objectives

This study aimed to investigate the influence of different obturation techniques compared to cold lateral compaction on the success rate of primary non-surgical endodontic treatments.

Materials and Methods

Systematic searches were performed for studies published up to May 17th, 2022 in MEDLINE/PubMed, Cochrane Library, Web of Science, Scopus, EMBASE, and Grey Literature Reports. Randomized clinical trials and nonrandomized (nonrandomized clinical trials, prospective or retrospective) studies that evaluated the success rate of primary non-surgical endodontic treatments obturated with the cold lateral compaction (control) and other obturation techniques were included. The revised Cochrane risk of bias tools for randomized trials (RoB 2) and nonrandomized studies of interventions (ROBINS-I) were used to evaluate the risk of bias. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool was used to evaluate the certainty of evidence.

Results

Eleven studies (4 randomized clinical trials (RCTs), 4 prospective, and 3 retrospectives) were included. Two RCTs were classified as having some concerns risk of bias and 2 as a low risk of bias. Two nonrandomized studies were classified as having a critical risk of bias and 5 as having a moderate risk of bias. The GRADE analysis demonstrated a very low to moderate certainty of evidence.

Conclusions

This systematic review generally evidenced no differences in the success rate of primary non-surgical endodontic treatments when the cold lateral compaction technique and other obturation techniques are performed. Further well-designed studies are still necessary.

A critical analysis of research methods and experimental models to study root canal fillings

Canal filling materials and techniques have been one of the most studied topics in Endodontics. A simple search using the mesh term "root canal filling" in PubMed revealed more than 11,000 articles, an impressive number that is much higher than "root canal disinfection" (5,544 articles) or even the popular "root canal preparation" (8,527 articles). The overriding importance attributed to root filling procedures is not merely intuitive. It derived from the appealing relevance given by the appearance of the white lines in common radiographs grounded on retrospective clinical data that had identified the quality of a root filling as one of the major causes of treatment failure (lack of healing). Since the publication of the Washington study, impressive efforts have been made for the release of new materials and techniques, as well as, for the development of a plethora of laboratory methods to assess the quality of root filling procedures. This narrative review aims to address and discuss the most relevant laboratory methods to assess the root canal filling. Since filling quality improvements have not translated into higher success rates, as reported in longitudinal clinical studies, more than to deliver a simple methodology-based review, this paper aims to present an in-depth critical view on the assessment of laboratory methods used to study the filling materials and techniques. Recent data indicate that the long-term dimensional stability/degradation over time of endodontic sealers plays a central role in the treatment outcome. In this context, laboratory methods should be developed focusing on predicting, at least to some degree, the long-term clinical behaviour of root canal fillings, rather than simply ranking different materials or techniques.

A micro-computed tomographic assessment of oval-shaped root canals obturated with bioceramic sealer using different obturation techniques

Background/Aim: To evaluate void volumes in oval-shaped root canals obturated with three different obturation systems using microcomputed tomography (micro-CT). Material and Methods: Twenty-four distal roots of mandibular molar teeth canals were prepared and randomly divided into three groups (n = 8 in each group). The canals were obturated using single cone (SC), GuttaCore (GC), and warm vertical compaction (WVC) techniques. Each specimen was scanned using a micro-CT device. The volumes of the voids were calculated, and the data were statistically analyzed using a one-way analysis of variance and post hoc Tukey's (P < .05). Results: The void volumes in the WVC group were significantly lower than those in the other groups (P < .05). When different root canal parts were examined, the void volumes increased significantly from the apical to the coronal level in the GC and SC groups (P < .05). In the WVC group, most voids were observed in the middle part (P < .05), whereas there was no significant difference in void volumes in the coronal and apical parts (P > .05). Conclusions: None of the systems provided void-free root filling. However, the void volume using the WVC system was significantly lower than that observed using the other systems.

Deficiencies in Root Canal Fillings Subsequent to Adaptive Instrumentation of Oval Canals

Simple Summary

Employing a chemo-mechanical preparation, one of the primary procedural phases in endodontic therapy is carefully removing debris, pulp tissue, and bacteria from the root canal system. The cross-sectional root canal shapes comprise circular, oval, long oval, flattened, or irregular. The frequency of oval root canals in the apical third of human teeth is around 25 to 50%. Motorised endodontic files leave almost 60% of the oval root canal perimeter unaffected by their instrumentation, thus resulting in faulty obturation that is required to prevent reinfection and to restrict the passage of microorganisms and toxins to and from the periapical tissue.

Abstract

The purpose of this study was to explore the influence of instrumentation and the potential for debris deposition using XP-endo shaper plus (XP-SP) and full-sequence SAF (F-SAF) on the adaption of thermoplastic root canal fillings in oval canals. Following the manufacturer’s instructions, ninety human permanent mandibular incisors with a single oval canal 6 mm from the apex (verified using pre-operative CBCT scanning) were instrumented with XP-SP and F-SAF. Obtura III Max apparatus was used for root canal obturation without the use of a root canal sealer. The roots were then sectioned 6 mm from the apex and examined with a digital stereomicroscope at x25 magnification to assess the root canal fillings. The F-SAF was associated with a significantly higher (p < 0.01) percentage of entire adaptation of the root fillings (76%) compared to the XP-SP (57%). Furthermore, the XP-SP group was also associated with higher (p < 0.01) defective obturation with debris at 17% and with voids at 26%. However, the F-SAF had lower percentages of defective obturations (7% with debris and 17% with voids). The quality of obturation of oval canals instrumented using full-sequence SAF was better.

Nanomaterials Application in Endodontics

In recent years, nanomaterials have become increasingly present in medicine, especially in dentistry. Their characteristics are proving to be very useful in clinical cases. Due to the intense research in the field of biomaterials and nanotechnology, the efficacy and possibilities of dental procedures have immensely expanded over the years. The nano size of materials allows them to exhibit properties not present in their larger-in-scale counterparts. The medical procedures in endodontics are time-consuming and mostly require several visits to be able to achieve the proper result. In this field of dentistry, there are still major issues about the removal of the mostly bacterial infection from the dental root canals. It has been confirmed that nanoparticles are much more efficient than traditional materials and appear to have superior properties when it comes to surface chemistry and bonding. Their unique antibacterial properties are also promising features in every medical procedure, especially in endodontics. High versatility of use of nanomaterials makes them a powerful tool in dental clinics, in a plethora of endodontic procedures, including pulp regeneration, drug delivery, root repair, disinfection, obturation and canal filling. This study focuses on summing up the current knowledge about the utility of nanomaterials in endodontics, their characteristics, advantages, disadvantages, and provides a number of reasons why research in this field should be continued.

The effect of atmospheric cold plasma on the dentinal tubule penetration of calcium silicate-based sealer used with different obturation techniques: A confocal laser scanning microscopy study

The aim of this study was to evaluate the effect of atmospheric cold plasma (ACP) on dentinal tubule penetration of EndoSequence BC. Sixty premolars were divided into four groups according to the obturation technique and plasma treatment. Root canals were filled with single cone in Group 1 (SC), single cone after ACP application in Group 2 (SC-P), warm vertical compaction in Group 3 (WVC), warm vertical compaction after ACP application in Group 4 (WVC-P). Horizontal sections were imaged using confocal laser scanning microscopy. The maximum penetration and percentage of penetration values were measured. These data were statistically analysed (P < 0.01). In the coronal region, the percentage of penetration values were higher in SC-P and WVC-P than in SC and WVC. In the middle region, SC-P and SC showed a higher penetration percentage than WVC and WVC-P. In the apical region, WVC showed a higher percentage of penetration value than SC-P, WVC-P and SC did. Maximum penetration of WVC was higher than of SC and SC-P. Within the limitations of this study, ACP improved the percentage of penetration values of EndoSequence BC when used with single-cone technique.

Micro-computed Tomographic Evaluation of the Quality of Root Canal Fillings in Mandibular Molars after Obturation for 54 Months

INTRODUCTION

The present study evaluated the percentage volume of voids in root canals of mandibular molars that had been obturated for 54 months.

METHODS

Thirty extracted human mandibular molars were instrumented and debrided. The teeth were assigned to 3 groups (n = 10) according to the filling technique and sealer used: the single-cone technique using AH Plus sealer (AHS; Dentsply Sirona Endodontics, Tulsa, OK) or EndoSequence BC sealer (BCS; Brasseler USA Dental LLC, Savannah, GA) and the warm vertical compaction technique using AH Plus sealer (AHW). The specimens were stored at 37°C and 100% humidity. Micro-computed tomographic imaging was used to scan each specimen 1 day 54 months after obturation. Data were analyzed using 1-way analysis of variance and the paired t test.

RESULTS

The percentage volume of voids in the teeth 1 day after obturation in the AHS group was higher than in the BCS group and the AHW group (P < .05). After 54 months, the proportion of voids decreased in all groups (P < .05). No significant difference was observed between the AHS group and the BCS group after 54 months. Teeth in the AHW group contained fewer voids than the AHS group (P < .05).

CONCLUSIONS

Voids in root canal filling were reduced 54 months after obturation. The warm vertical compaction technique achieved better root canal filling quality in mandibular molars than the single-cone technique when using AHS after long-term storage at 100% humidity.

The investigation of thermal behaviour and physical properties of several types of contemporary gutta-percha points

Aim

To analyse the contents and thermal behaviour of several brands of contemporary gutta‐percha points due to the variable nature of the components of gutta‐percha, and the impact they can have on the physical properties of this unique material during canal filling.

Methodology

Six brands of gutta‐percha were investigated: Conform Fit ^TM Gutta‐Percha Points for ProTaper Gold® (PTG) (Dentsply Sirona), ProTaper® Universal Gutta‐Percha Points (PTU) (Dentsply Sirona), Autofit ^TM Feathered Tip Gutta Percha (Kerr), Mtwo® Gutta‐Percha (VDW), Gutta Percha Root Canal Points (GC, GC Corporation) and Gutta‐Percha Points ISO Color‐Coded (ISO; Dentsply Sirona). The organic and inorganic fractions of gutta‐percha points were separated by quantitative chemical analysis. Thermal conductivity was detected using a laser flash method. In addition, the thermal behaviour of gutta‐percha in response to temperature variations was analysed using differential scanning calorimetry (DSC). Kruskal–Wallis and Dunn tests were applied for comparisons amongst groups for chemical compositions and temperature obtained from DSC. The associations between compositions and thermal conductivity were determined using simple linear regression. A p value <.05 was considered to be statistically significant.

Results

There were significant difference in the inorganic fractions of the gutta‐percha points in percentage by weight amongst the groups (p < .05). PTG had the lowest thermal conductivity (0.42 W/m K). A positive correlation was observed between the percentage of inorganic fraction and thermal conductivity (r = 0.95). The initial phase changing temperature and peak temperature measured by DSC were significantly different when the β‐form transformed to α‐form (p < .05), whereas no significant difference was found during the α‐form to the amorphous‐phase transition (p > .05).

Conclusions

Chemical compositions and initial phase changing temperature by DSC varied according to the various brands of gutta‐percha points. Conform Fit ^TM gutta‐percha had the lowest percentage of inorganic fraction and thermal conductivity amongst these six brands of gutta‐percha. Thermal conductivity had the strongest positive correlation with the percentage of inorganic components and zinc, whilst there was a negative correlation to the amount (ratio) of gutta‐percha.

Efficacy of XP-endo instruments in removing 54 month-aged root canal filling material from mandibular molars

OBJECTIVE

To investigate the effectiveness of XP-endo Shaper (XPS) and XP-endo Finisher R (XPFR) instruments in removing aged root filling material from root-treated mandibular molars.

METHODS

Thirty mandibular molars were instrumented and divided into three groups: single-cone obturation using AH Plus sealer (AHS) or EndoSequence BC sealer (BCS), and warm vertical compaction using AH Plus sealer (AHW). The specimens were stored at 100% humidity and 37 °C for 54 months. Retreatment was performed using XPS and XPFR. Micro-computed tomography was used to scan the specimens after 54 months, after XPS retreatment and after the supplementary approach using XPFR.

RESULTS

The XPS removed more filling material in the BCS and AHS groups, compared with the AHW group (P < 0.05). After supplementary instrumentation XPFR, the proportion of the remaining filling material decreased significantly in all groups (P < 0.05). The XPFR instruments were more efficient in removing filling material in the BCS group than in the AHS or AHW group (P < 0.05). The combined use of XPS and XPFR instruments efficiently removed filling material in the BCS group, followed by the AHS and AHW groups (P < 0.05).

CONCLUSIONS

Although the combined use of XPS and XPFR instruments helped remove the bulk of aged root filling material from mandibular molars, material removal from canals filled using warm vertical condensation in the critical apical area remains a concern.

CLINICAL SIGNIFICANCE

Removal of the aged filling materials using XP-endo instruments from the apical area is challenging when instrumented root canals are filled using warm vertical condensation.

Porosity Distribution in Single Cone Root Canal Fillings Performed by Operators with Different Clinical Experience: A microCT Assessment

The objective of this study was to assess the porosity distribution of BioRoot RCS/single gutta-percha point root-canal fillings performed by a general dental practitioner and endodontist. Fourteen plastic models of maxillary premolars with two roots were selected and shaped with HyFlex EDM instruments to a size 40/0.04 taper and randomly divided into two experimental groups. A total of 14 canals in each group were obturated by two different operators with one HyFlex EDM size 40 gutta-percha point and BioRoot RCS sealer. The specimens were scanned with a high-resolution micro-computed tomography scanner, and the porosity of the fillings at the coronal, middle, and apical thirds of the root canals was qualified and quantified. The differences between groups and root-canal thirds were compared using Mann–Whitney, Friedman, and Wilcoxon tests with the significance level set at p < 0.05. The highest number of pores was observed in the apical third of root-canal fillings in both groups; however, the porosity distribution between the two groups was not significantly different in the apical and middle thirds (p > 0.05). Statistically significant differences were determined only in the coronal third (p < 0.05). The predominance of open pores was detected in all root-canal thirds and groups, with no significant differences in the number of open pores between the coronal and middle thirds (p > 0.05).

The effect of different confluence confirmation strategies on the obturation of Vertucci type II canal: micro-CT analysis

Objectives

The present study aims to compare the obturation quality of 2 confluence confirmation techniques in artificial maxillary first premolars showing Vertucci type II root canal configuration.

Materials and Methods

Thirty artificial maxillary premolars having Vertucci type II root canal configuration were made. They were divided into 3 groups according to the confluence confirmation technique as follows. Gutta-percha indentation (GPI) group (confluence confirmation using a gutta-percha cone and a K file); electronic apex locator (EAL) group (confluence confirmation using K files and EAL); and no confluence detection (NCD) group. In the GPI group and the EAL group, shaping and obturation were performed with the modified working length (WL). In the NCD group, shaping was performed without WL adjustment and obturation was carried out with an adjusted master cone. Micro-computed tomography was used before preparation and after obturation to calculate the percentage of gutta-percha occupied volume (%GPv) and the volume increase in the apical 4 mm. Data were analyzed using 1-way analysis of variance and post hoc Tukey's test.

Results

Statistically significant difference was not found in terms of the %GPv from the apex to apical 4 mm. However, the NCD group showed a statistically significant volume increase compared with the EAL group (p < 0.05).

Conclusions

In terms of gutta-percha occupied volume, no significant difference was observed among the 3 groups. Confluence confirmation using an EAL in teeth with Vertucci type II configuration showed less volume increase during canal shaping compared with no confluence confirmation.

Microcomputed Tomographic Assessment of the Single Cone Root Canal Fillings Performed by Undergraduate Student, Postgraduate Student and Specialist Endodontist

The present study evaluated the obturation quality of root canals filled with BioRoot RCS sealer and single gutta-percha point by undergraduate student (US), postgraduate student (PS) and endodontist (ED). Twenty-one plastic models of upper premolars were enlarged with HyFlex EDM instruments to a size 40/0.04 taper and randomly divided into three groups (7 teeth/14 canals per group): US, PS and ED. After the obturation of root canals with BioRoot RCS and one HyFlex EDM size 40 gutta-percha point, plastic models were scanned using micro-computed tomography scanner (µCT) SkyScan 1272 at isotropic resolution of 10 µm. The porosity distribution was evaluated separately for the apical, middle and coronal thirds. The Kruskal–Wallis, Mann–Whitney, Friedman and Wilcoxon tests with the significance level set at 5% were used for data analysis. The µCT evaluation revealed open pores being the dominant type of porosity in all experimental groups and root canal thirds, with the highest percentage of pores in the apical third of root canal fillings. The quality and homogeneity of single cone root canals fillings remained similar between the groups in the apical and middle thirds (p > 0.05). Significant differences were observed only in the coronal third (p < 0.05).

Micro-CT Evaluation of Four Root Canal Obturation Techniques

PURPOSE

The aim of this in vitro study was to evaluate the quality of four root canal obturation techniques using microcomputed tomography (micro-CT).

MATERIALS AND METHODS

A total of 36 mandibular first premolars with mostly round canals were decoronated, then instrumented up to a size F3 rotary file, and dressed with an epoxy resin-based sealer. Subsequently, they were divided into 4 different groups (n = 9) based on the method of obturation: lateral condensation using 0.02 tapered master cone (LC2), lateral condensation using 0.04 tapered master cone (LC4), matched single-cone technique (MS), and matched single cone-mediated ultrasonic activation (MSUA). All the teeth were scanned using micro-CT (resolution of 19 μm), and the percentage volume of voids was calculated. One-way analysis of variance and Tukey test were used to analyze the data (α = 0.05).

RESULTS

The total percentage volume of voids was significantly lower in the MSUA group compared to all other groups (P < 0.05). The total percentage volume of voids was significantly lower in the MS group compared to the LC4 (P < 0.001) and LC2 (P < 0.001) groups. However, there was no significant difference between the LC2 and LC4 groups (P < 0.65).

CONCLUSIONS

MSUA, significantly, showed the least root canal filling voids amongst all the obturation techniques studied. MSUA can be considered an effective method for the filling of the round root canals. In general, lateral condensation using either 0.02 or 0.04 tapered master cones had significantly the highest volume percentage of voids amongst the experimental groups.

Correlation among Root Canal Configuration, Quality of Filling, and Its Sealability

Objective  This study aimed to evaluate the existence of possible correlations among root canal configuration, quality of filling, and its sealability.

Materials and Methods  Sixty human mandibular central incisors were selected for this study. The teeth were prepared with the Profile 04 system up to instrument 35/0.04 and irrigated with 2.5 mL of 2.5% sodium hypochlorite at each instrument change. Root canal filling was performed by the lateral compaction technique, using gutta-percha and an epoxy resin-based sealer (AH Plus) labeled with 0.1% Rhodamine B dye. Afterward, the specimens were submitted to fluid filtration tests to assess the sealability of the filling. Cross-sections were obtained at −3, −6, and −8 mm from the root apex and submitted to a metallographic treatment to determine the root canal configuration and the percentage of gutta-percha filled areas. The data were statistically analyzed by the Grubbs test. Pairs of correlations were analyzed by applying the Spearman test at a level of significance of 5%.

Results  No correlation was observed among the analyzed variables as follows: root canal configuration versus filling quality (Spearman’s rho = 0.031); filling quality versus sealability (Spearman’s rho = 0.219); and root canal configuration versus sealability (Spearman’s rho = 0.184).

Conclusion  The root canal configuration did not affect the quality of the filling and its sealability.

Filling quality of several obturation techniques in the presence of apically separated instruments: A Micro-CT study

Separated root canal instruments may affect the quality of root canal obturation and hence the survival of endodontically treated teeth. Obturation techniques may influence filling-quality. The aim was to evaluate the obturation quality of teeth filled with different obturation techniques in the presence of apically separated instruments using micro-computed tomography (μ-CT). Notched ProTaper F2 rotary-files were separated in the apical third of 36-human mandibular incisors with single root/canal and mature apex. Samples were filled by an endodontist according to one of the following obturation techniques (n = 12): cold lateral-compaction (CLC), single-cone (SC) and thermoplastic injection (TI). Samples were scanned by the Skyscan 1,274® μ-CT device after 1-week at 37°C in 100% humidity. Images of the sections were evaluated with CTan software in terms of total-volume and volume percentage of the filling materials and voids between coronal end of the separated instrument and gutta-percha/sealer filled void-free sections. Data was analyzed using Kruskal-Wallis and Mann Whitney-U tests with a significance level of 5%. Kruskal-Wallis revealed differences among groups (p < 0.05).Pairwise comparisons revealed that less volume of voids were measured in SC (0.02 ± 0.03 mm³ ) compared to CLC (0.15 ± 0.16 mm³ ) and TI (0.18 ± 0.24 mm³ ) (p < 0.05); while TI was statistically similar with CLC (p > 0.05). Percentages of volumes of voids and filling materials were as follows for SC, CLC and TI, respectively: 8.88 ± 18.52% and 24.45 ± 38.40%, 46.92 ± 33.53% and 53.07 ± 33.53%, 40.54 ± 33.85% and 42.79 ± 34.45%. The obturation technique may have a significant impact on the volume of voids in the presence of a separated file. No obturation technique produced a void-free root canal filling.

Use of mind maps in dental education: An activity performed in a preclinical endodontic course

PURPOSE/OBJECTIVES

(1) to assess the ability of dental students to use mind maps to express the relationships of endodontic theory and technique; (2) to explore features illustrated from the highest- and lowest-graded mind maps; and (3) to evaluate improvements in successive mind maps from the same student.

METHODS

A total of 31 second-year students were asked to configure a mind map on root canal cleaning-shaping and then 18 weeks later develop a second mind map on root canal obturation. Faculty visually analyzed the mind maps using a qualitative approach: a multilayered process of thematic analysis. Codes and themes were generated to investigate if students were able to express appropriate and evidence-based ideas on the topics (accuracy of relationships and depth of information presented). Two of the highest- and 2 of the lowest-graded mind maps for each activity were directly compared. Improvement by the same student from the first to second mind map was also evaluated based on trend/style and creativity.

RESULTS

The majority of the students accurately expressed the scientific basis for root canal cleaning-shaping and obturation. The highest-graded mind maps displayed the biomedical and humanistic conceptions of critical thinking. In comparing the second mind map to the first, nearly 50% of the students incorporated more detail and artistic expression in the second map.

CONCLUSIONS

using mind maps in dental education can benefit students with different learning styles and help the instructor to identify the level of conceptualization that the student had developed about a topic.

Microscopic and chemical evaluation of the filling quality of five obturation techniques in oval-shaped root canals

OBJECTIVES

The aim of this study was to assess the filling quality of five obturation techniques in oval-shaped root canals.

MATERIALS AND METHODS

A total of 212 mandibular first molars with one distal oval canal were selected. Distal canals, shaped with WaveOne Gold Primary, were randomly divided in five groups (n = 40) for obturation: continuous wave condensation, GuttaCore, Thermafil, single cone with AH plus, and single cone with BioRoot RCS. The proportions of gutta-percha-filled areas (GPFA), sealer-filled areas (SFA), void areas (VA), and the sealer/gutta tags into dentinal tubules at 4 mm and 2 mm from the apex were analyzed by an optical numeric microscope, SEM, and energy-dispersive X-ray (EDX). Data were then compared by Kruskal-Wallis one-way ANOVA on ranks (α = 0.05).

RESULTS

At 4 mm, a statistically significant higher GPFA and lower SFA were observed in the GuttaCore and Thermafil groups compared with the 3 other groups. A statistically significant lower VA was observed in the continuous wave condensation, GuttaCore, and Thermafil groups than in the two single-cone groups. At 2 mm, there were a statistically significant higher GPFA and lower SFA and VA in GuttaCore and Thermafil groups than in the 3 other groups. At the two levels investigated, the presence of gutta-percha tags was clearly demonstrated for GuttaCore and Thermafil groups; no tags were observed in the 3 other groups.

CONCLUSIONS

Obturation quality was overall improved in GuttaCore and Thermafil groups.

CLINICAL RELEVANCE

Carrier-based techniques may significantly improve the filling quality compared to continuous wave condensation and single-cone technique. The single-cone technique might have inherent limitations especially in oval root canals regardless of the sealer used.

The Influence of Brushing Movement on Geometrical Shaping Outcomes: A Micro-CT Study

Brushing motion has been proposed for endodontic single-file reciprocating systems to eliminate coronal interferences, but it may hesitate in a less conservative root canal shaping. The aim of the study was to compare the maintenance of the original root canal anatomy using the WaveOne Gold (WOG) technique with or without a brushing motion. Sixty extracted human mandibular first molars were selected. Manual canal scouting and mechanical glide path were performed. Samples were randomized into two groups (n = 30): WOG Primary was used to shape the mesio-lingual canals without (NB group) or with (B group) an intentional brushing motion. Specimens were scanned with micro-computed tomography (micro-CT) before and after instrumentation in order to match the volumes. Increases in canal volume and surface area were measured. Centroid shift and thickness of removed dentine from the inner curvature were assessed at the furcation, 1.5 mm and 3 mm apically from the furcation, and in relation to the point of maximum curvature. Data were analyzed by one-way ANOVA and post-hoc Student–Newmann–Keuls tests (p < 0.05). No brushing technique resulted in being significantly associated with a better maintenance of the canal anatomy, especially in the coronal third (p < 0.05). When using the WOG system, a no-brushing technique resulted in less invasive shaping, reducing the risk of stripping.

Comparison of apical sealing ability of bioceramic sealer and epoxy resin-based sealer using the fluid filtration technique and scanning electron microscopy

Background/purpose

A perfect sealing of root canal system is essential for preventing ingress of bacteria from the oral environment. The purpose of this study was to evaluate the apical sealing ability of bioceramic (EndoSequence BC Sealer®) and epoxy resin-based (AH Plus®) sealers at 24 h, 7 days and 4 weeks.

Materials and methods

Forty two extracted human upper anterior teeth were sectioned to leave the root 15-mm long, then all the roots were instrumented using a set of ProTaper® rotary instruments. Four roots were selected randomly as controls, and the remaining 38 roots were randomly divided into 2 groups of 19 roots each: group 1: EndoSequence BC Sealer® and gutta-percha, and group 2: AH Plus® and gutta-percha using a multiple wave condensation technique. The apical sealing ability of the filled root canal was measured using the fluid filtration method with 200 mmHg (26.67 KPa) above atmospheric pressure at 24 h, 7 days and 4 weeks. Scanning electron microscopy (SEM) was used to assess the adaptation and penetration of the sealers. The apical microleakage between 2 groups was compared using Student's t-test. P < 0.05 was considered statistically significant.

Results

EndoSequence BC Sealer® had significantly better sealing ability than AH Plus® at all test periods (P < 0.001). SEM showed EndoSequence BC Sealer® had better penetration into dentinal tubules.

Conclusion

Bioceramic sealer could promote proper sealing of root canals obturated with multiple wave condensation.

A micro-computed tomographic evaluation of root canal filling with a single gutta-percha cone and calcium silicate sealer

Objectives

The purpose of this study was to evaluate the void of root canal filling over time when a calcium silicate sealer was used in the single gutta-percha cone technique.

Materials and Methods

Twenty-four J-shaped simulated root canals and twenty-four palatal root canals from extracted human maxillary molars were instrumented with ProFile Ni-Ti rotary instruments up to size 35/0.06 or size 40/0.06, respectively. Half of the canals were filled with Endoseal MTA and the other half were with AH Plus Jet using the single gutta-percha cone technique. Immediately after and 4 weeks after the root canal filling, the samples were scanned using micro-computed tomography at a resolution of 12.8 μm. The scanned images were reconstructed using the NRecon software and the void percentages were calculated using the CTan software, and statistically analyzed by 1-way analysis of variance, paired t-test and Tukey post hoc test.

Results

After 4 weeks, there were no significant changes in the void percentages at all levels in both material groups (p > 0.05), except at the apical level of the AH Plus Jet group (p < 0.05) in the simulated root canal showing more void percentage compared to other groups. Immediately after filling the extracted human root canals, the Endoseal MTA group showed significantly less void percentage compared to the AH Plus Jet group (p < 0.05).

Conclusions

Under the limitations of this study, the Endoseal MTA does not seem to reduce the voids over time.

Fracture resistance of roots enlarged with various rotary systems and obturated with different sealers

Background. This in vitro study compared the fracture resistance of roots instrumented either with ProTaper or One Shape rotary systems and filled with one of the silicate, epoxy resin or silicone-based sealers. Methods. Sixty single-rooted extracted mandibular premolars were decoronated to a length of 13 mm and then randomly divided into two main groups (n=30) in terms of the rotary system used for preparation. Group 1 samples were instrumented with the ProTaper Universal system up to a master apical file of #F2, while samples in group 2 were enlarged with One Shape system. The two main groups were then divided into 3 subgroups in terms of the sealer used (n=10) and filled with guttapercha (either F2 or MM-GP points) of the rotary system used and one of the sealers as follows: group 1, BioRoot RCS + ProTaper F2 gutta-percha; group 2, AH Plus + ProTaper F2 gutta-percha; group 3, GuttaFlow + ProTaper F2 gutta-percha; group 4, BioRoot RCS+ MM-GP points; group 5, AH Plus + MM-GP points; and group 6, GuttaFlow + MM-GP points. Each specimen then underwent fracture testing by using a universal testing machine at a crosshead speed of 1.0 mm/min until the root fractured. Data were statistically analyzed. Results. Two-way ANOVA showed no significant differences between the groups. One Shape instruments showed significantly better fracture resistance compared to ProTaper instruments. Statistically, no significant difference was found between AHPlus, GuttaFlow and BioRoot RCS sealers. Conclusion. It can be concluded that the rotary system used for the instrumentation of teeth has some influence on the fracture resistance, while the root canal sealers do not have such an effect.

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.

Sealability of Different Root Canal Nanosealers: Nano Calcium Hydroxide and Nano Bioactive Glass

Background:

The success of the endodontic treatment is largely dependent on the sealing achieved by root canal obturation. The application of sealer fills imperfections and increases adaptation of the root filling to the canal walls.

Aim:

To evaluate the sealability of experimental nanosealers (nano calcium hydroxide and nano bioactive glass) and to compare it with the commercial zinc oxide eugenol sealer using a dye penetration method.

Materials and Methods:

Sixty single-rooted mandibular premolars were selected. The tooth crowns were removed so as to obtain standardized 15-mm-long root specimens. The root canal was instrumented with Protaper Ni-Ti rotary file and the final file size was up to # F4/.06 (in vitro study). They were then randomly allocated into 3 groups of 20 specimens each (n=20) according to the sealer used for obturation, and all samples were filled with single cone gutta-percha (#40/06) and one of the tested sealers. All teeth were coated with nail polish and then suspended in 2% methylene blue dye for 7 days. Stereo-microscope (x10) was used to evaluate the sealability of newly introduced nanosealers. The data were statistically analyzed by ANOVA test followed by post hoc analysis (P < 0.05).

Results:

Significant improvement shown by the presented study suggests that nano calcium hydroxide sealer showed significantly less dye leakage than nano bioactive glass sealer and zinc oxide eugenol sealer.

Conclusion:

The results of this study showed that the synthesized nano-powder sealers are suitable for use in root canal therapy to prevent leakage.

The root canal can be sealed better by using smaller nano-powder particle sizes. In addition, the two groups exhibited significant differences in leakage in comparison with commonly used ZOE sealer.

Quality of Root Filling after Obturation with Gutta-percha and 3 Different Sealers of Minimally Instrumented Root canals of the Maxillary First Molar

INTRODUCTION

The aim of this study was to compare the quality of root fillings completed by a modified single-cone (MSC) technique with 3 different sealers after minimal instrumentation and multisonic cleaning of root canals of maxillary first molars.

METHODS

Root canals of 18 maxillary first molars were instrumented to size 15/.04 taper using rotary files. Sodium hypochlorite 5.25% was used during instrumentation; the final cleaning was performed by the GentleWave System (Sonendo Inc, Laguna Hills, CA). The specimens were allocated into 3 groups and root filled by the MSC technique using a size fitted gutta-percha master cone and GuttaFlow Bioseal (Coltene Whaledent GmBH + Co KG, Langenau, Switzerland), GuttaFlow 2 (Coltene Whaledent GmBH + Co KG), and MTA Fillapex (Angelus Industria de Produtos Odontológicos S/A, Londrina, PR, Brazil) sealers. Micro-computed tomographic scans were obtained before and after instrumentation, post-GentleWave, and after obturation. Reconstructed images were analyzed for the volumetric percentage of filling materials. Mesiobuccal roots of the selected teeth were sectioned at 0.5-mm increments starting at the apex of the root. The cross sections were further examined using a light microscope.

RESULTS

The 3 groups had 90%-99% of the canal space filled with the root filling material. The mean volume of the filling material was higher in the GuttaFlow Bioseal and GuttaFlow 2 groups than in the MTA Fillapex group (P < .05). There was no significant difference among the apical, middle, and coronal thirds. The cross-sectional images showed no obvious gaps or voids in the GuttaFlow groups. After instrumentation, 49 of the 189 canal thirds (25.9%) had hard tissue debris in the root canal system. After GentleWave cleaning, only 4 of 63 canals (6.3%) and 4 of the 189 canal thirds (2.1%) still had debris.

CONCLUSIONS

The MSC method with GuttaFlow 2 and GuttaFlow Bioseal sealers after multisonic cleaning of minimally instrumented molar canals resulted in high-quality root fillings. Multisonic cleaning of minimally instrumented molars seems to be effective in debris removal.

The push-out bond strength of calcium silicate-based endodontic sealers

Background

The aim was to compare the dislodgement resistance of calcium silicate-based sealers (Total Fill BC Sealer, Endo CPM Sealer, BioRoot RCS) with an epoxy resin-based sealer (AH Plus).

Methods

The root canals of 80 single-rooted human teeth were instrumented with F360 up to size 45.04. All canals were obturated using matching gutta-percha cones according to the single-cone technique in combination with one of the mentioned sealers (n = 20 per group). After eight weeks of incubation (37 °C, 100% humidity), the roots were embedded in resin. Starting with a distance of 7 mm from the apex, four slices of 1 mm thickness were cut. Dislodgement resistance was measured using a universal testing machine and the push-out bond strength was calculated. Specimens were examined under 4×-magnification to determine the mode of bond failure. Statistical analysis was performed using ANOVA and Student-Newman-Keuls-test.

Results

Regarding the pooled data of all sections, the push-out bond strength of AH Plus was significantly higher than the push-out bond strength of all calcium silicate-containing sealers (P < 0.05). Out of all calcium silicate-based sealers, Total Fill BC Sealer showed the highest push-out bond strength (P < 0.05). BioRoot RCS had significant higher push-out bond strength than Endo CPM Sealer (P < 0.05). Nearly the same results were found for all four sections. BioRoot RCS only differed significantly from Endo CPM Sealer in the third section (P < 0.05).

Conclusions

The push-out bond strength of the investigated calcium silicate-based sealers was lower than of AH Plus. Total Fill BC showed the highest push-out bond strength of the calcium silicate-based sealers.

Clinical audit training improves undergraduates' performance in root canal therapy

AIM

To evaluate the effectiveness of clinical audit-feedback cycle as an educational tool in improving the technical quality of root canal therapy (RCT) and compliance with record keeping performed by dental undergraduates.

METHODS

Clinical audit learning was introduced in Year 3 of a 5-year curriculum for dental undergraduates. During classroom activities, students were briefed on clinical audit, selected their audit topics in groups of 5 or 6 students, and prepared and presented their audit protocols. One chosen topic was RCT, in which 3 different cohorts of Year 3 students conducted retrospective audits of patients' records in 2012, 2014 and 2015 for their compliance with recommended record keeping criteria and their performance in RCT. Students were trained by and calibrated against an endodontist (κ ≥ 0.8). After each audit, the findings were reported in class, and recommendations were made for improvement in performance of RCT and record keeping. Students' compliance with published guidelines was presented and their RCT performances in each year were compared using the chi-square test.

RESULTS

Overall compliance with of record keeping guidelines was 44.1% in 2012, 79.6% in 2014 and 94.6% in 2015 (P = .001). In the 2012 audit, acceptable extension, condensation and the absence of mishap were observed in 72.4, 75.7% and 91.5%; in the 2014 audit, 95.1%, 64.8% and 51.4%; and in 2015 audit, 96.4%, 82.1% and 92.8% of cases, respectively. In 2015, 76.8% of root canal fillings met all 3 technical quality criteria when compared to 48.6% in 2014 and 44.7% in 2012 (P = .001).

CONCLUSION

Clinical audit-feedback cycle is an effective educational tool for improving dental undergraduates' compliance with record keeping and performance in the technical quality of RCT.

Comparative evaluation of the vertical fracture resistance of endodontically treated roots filled with Gutta-percha and Resilon: a meta-analysis of in vitro studies

Background

Teeth treated endodontically are more susceptible to vertical root fracture (VRF). Some studies have suggested that obturating the root canals with Gutta-percha or Resilon can reinforce endodontically treated teeth, but a few others have presented conflicting results. These inconsistent results cannot guide clinicians in determining clinical approaches. The objective of this meta-analysis is to evaluate and compare the vertical fracture resistance of endodontically treated root canals obturated with Gutta-percha/AH plus and the Resilon system.

Methods

Comprehensive literature searches were performed in the PubMed, Cochrane Library, ScienceDirect, Web of Science and Embase databases. The titles and abstracts of all of the retrieved articles were independently assessed by two authors according to predefined selection criteria. Data in the included articles were independently extracted. Statistical analyses were conducted using Review Manager 5.3 and Stata 12.0 software. The pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated for the outcome indicators. The level of statistical significance was set at p < 0.05. The Cochran Q test (I² test) was used to test for heterogeneity among studies.

Results

Fourteen randomized controlled in vitro trials were included in the meta-analysis. The results demonstrated that the vertical root fracture resistance of unprepared and unfilled roots was significantly higher than that of roots obturated with Gutta-percha/AH plus (SMD = − 0.69, 95% CI = − 1.34 to − 0.04, p = 0.04) or the Resilon system (SMD = − 0.54, 95% CI = − 1.07 to − 0.00, p = 0.05). The differences in fracture resistance between the roots filled with Gutta-percha/AH plus and the prepared unfilled root canals was not significant (SMD = 0.59, 95% CI = − 0.02 to 1.21, p = 0.06). Roots obturated with Resilon had higher fracture resistance than instrumented unfilled roots (SMD = 0.83, 95% CI = 0.44 to 1.22, p < 0.0001) or roots filled with Gutta-percha/AH plus (SMD = 0.62, 95% CI = 0.01 to 1.23, p = 0.05).

Conclusions

The present study suggests that filling with Gutta-percha/AH plus dose not reinforce endodontically treated roots, whereas obturating with the Resilon system can increase vertical root fracture resistance of prepared roots. As this meta-analysis was based on in vitro studies, it should be careful to extrapolate its conclusion to the clinical context.