Quality of thermoplasticized and single point root fillings assessed by micro-computed tomography

Obturation quality of bioceramic sealers with different obturation techniques: a micro-CT evaluation

This micro-computed tomography (micro-CT) analysis in vitro study was designed to compare void volume in root canal fillings performed using the single-cone (SC) technique and the continuous wave condensation (CWC) technique with bioceramic (BC) sealer. Forty human-extracted, single-rooted mandibular premolars were cleaned, shaped, and divided into two groups (n = 20) based on the obturation technique. In the first group, obturation was performed using the CWC technique with TotalFill HiFlow BC sealer. In the second group, obturation was performed using the SC technique with the conventional TotalFill BC sealer. All roots were scanned with micro-CT, and ©CTAn software version 1.20.8.0 was used to measure the void volume of each root third in all samples. Despite the different obturation techniques, both groups exhibited voids in filled root canals. The overall mean void volume in the SC group (0.253 ± 0.186) was significantly higher (p = 0.000) than that in the CWC group (0.035 ± 0.043). The difference was significant in the coronal (p = 0.000) and middle (p = 0.017) thirds. The CWC technique with TotalFill HiFlow BC sealer achieved superior obturation quality compared to the SC technique with conventional BC sealer in oval-shaped premolars.

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.

Ex-vivo evaluation of clinically-set hydraulic sealers used with different canal dryness protocols and obturation techniques: a randomized clinical trial

OBJECTIVES

This 2-part randomized parallel triple-blind clinical trial adopts a unique model assessing clinically-set hydraulic calcium silicate-based sealers (HCSBS) after different root canal dryness protocols and obturation techniques.

METHODS

For the first phase of the study, 24 teeth scheduled for orthodontic extractions were allocated into four groups according to the canal dryness protocol and the obturation technique. G1 (CLC-AHP): cold lateral compaction (CLC) with AH Plus sealer, G2 (CLC-ES-SD): CLC with Endosequence (ES) after standard canal(s) dryness (SD); G3 (SC-ES-SD): matching single-cone (SC) with ES after SD; G4 (SC-ES-PD): as G3 but after partial canal(s) dryness (PD). Teeth were extracted after one month of clinical service and examined for intracanal voids by micro-CT (2D & 3D). For the 2nd phase, another 24 teeth were allocated into four groups according to the root canal dryness protocol and the HCSBS used (ES or CeraSeal (CeS)). Teeth were extracted after one month and sectioned vertically for energy dispersive X-ray (EDX)/scanning electron microscope (SEM) examination. One-way ANOVA with Games-Howell post-hoc test and Chi-square test with multiple z-tests were used for statistical analysis.

RESULTS

SC-PD showed the highest percentage of voids (p < 0.05). MicroCT scans as well as EDX/SEM examination showed that PD resulted in significantly larger interfacial gaps (p < 0.001) with more hydration products at the sealer/dentin interface than SD.

CONCLUSIONS

Both tested dryness protocols allowed the hydration of HCSBS and the formation of hydration products, thus standard dryness is recommended to reduce the incidence of intracanal voids.

CLINICAL RELEVANCE

When using the single-cone obturation technique, intentional root canal moisture negatively affects the performance of HCSBS.

PROTOCOL REGISTRATION

http://www.

CLINICALTRIALS

gov, ID: NCT05808062.

Mineral trioxide aggregate obturation quality with two obturation techniques in severe curved root canals - a micro-CT study

BACKGROUND

The existence of voids within the mineral trioxide aggregate (MTA) composition is one of the factors that can influence the treatment outcome. The primary objective of this study was to quantitatively assess and compare the MTA orthograde obturation quality in severe curved root canals using two different MTA compaction techniques: manual compaction with K-file, or Auger technique using micro-computed tomography (micro-CT) imaging.

METHODS

For this study, 26 mandibular first molar teeth with severely curved mesiobuccal root canals were selected. These samples were randomly divided into two groups. All root canals were instrumented using ProTaper Gold rotary files up to the F3 file at the working length. In one group, OrthoMTA was compacted using a stainless steel K-file, while in the other group, the Auger technique was employed for compaction into the root canals. Once the MTA had completely set, the filled root canals were subjected to scanning using a high-resolution micro-CT scanner. The porosity volume was determined as a percentage in relation to the overal volume of the canal, and the collected data were subjected to analysis using SPSS software, with the significance level set at P < 0.05.

RESULTS

The two techniques had no significant difference in open, closed, and total mean porosity. In both groups, the mean of open porosity was significantly more than closed porosity.

CONCLUSIONS

According to the results of the present study, neither of these two techniques is preferred to the other, and factors such as working time, etc., can be considered to choose the more appropriate clinical technique.

Field Emission Scanning Electron Microscope Analysis of the Marginal Adaptation of Various Root Canal Sealers at the Dentin-Sealer and Sealer-Guttapercha Interfaces at Three Root Canal Levels: An In Vitro Study

Aims An in vitro evaluation of the marginal adaptation of four root canal sealer variants at the dentin-sealer and sealer gutta-percha interfaces in the coronal, middle, and apical thirds of root canals was conducted using field emission scanning electron microscope (FESEM) analysis.  Materials and methods In total, 80 extracted human mandibular premolar teeth were used in this study. All teeth were decoronated to standardize the root length to 14 mm. A round bur was used to gain access into canal orifices and the working length was determined. Root canal instrumentation was performed using the crown-down technique with ProTaper Next rotary files up to size X3, along with the use of root canal irrigants. All specimens were then randomly divided into four groups, with 20 specimens per group, depending on the root canal sealer used: Group A consisted of AH Plus (Dentsply Maillefer, Ballaigues, Switzerland), Group B of MTA-Fillapex (Angelus Dental, Londrina, Brazil), Group C of Bio-C Sealer (Angelus Dental), and Group D of GuttaFlow-2 (Coltene Whaledent, Altstatten, Switzerland). All specimens were obturated with size X3 gutta-percha points uniformly coated with respective sealers in the single-cone technique and coronal access was sealed with glass ionomer cement. The specimens were incubated for seven days and then horizontally sectioned at the coronal, middle, and apical thirds of the root canals. On each sample obtained, three points were randomly chosen and both sealer-dentin and sealer gutta-percha interfaces were examined under FESEM at 1000x magnification. The marginal gaps of all four sealers at both interfaces and at three levels of root canals were measured in µm and values were recorded, tabulated, and used for data analysis. One-way analysis of variance (ANOVA) and post hoc Bonferroni tests were used for statistical analysis. A p-value ≤ 0.05 was considered statistically significant. Results Compared to the sealer gutta-percha interface, AH Plus, MTA-Fillapex, and Bio-C sealers at all three levels of the root canals showed more marginal gaps at the sealer-dentin interface with a significant difference (p<0.05). However, the GuttaFlow-2 sealer showed no significant difference (P > 0.05).  Conclusions The marginal adaptation of the GuttaFlow-2 sealer is superior to both dentin and gutta-percha at the coronal, middle, and apical thirds of root canals compared to other sealers used in the study.

Comparative Evaluation of the Quality of Obturation Between Three Obturation Techniques in Primary Canines: An In Vitro Study

Aims This study compares three obturation techniques (rotary lentulo spiral, handheld lentulo spiral, and pressure syringe) for the quality of two filling pastes (zinc oxide eugenol (ZOE) paste and Metapex (Meta Biomed Co., Ltd., Chungcheongbuk-do, Korea). Methods and materials Sixty extracted primary canines were instrumented and obturated by filling materials. The obturation techniques were divided into three groups according to different obturation techniques. Obturation quality was evaluated for length, density, and presence of voids by using digital radiography. Results This study showed that the handheld lentulo spiral technique using Metapex and ZOE exhibited more optimal fillings for obturation length. The highest density obturation was achieved using the syringe injection approach with Metapex and ZOE. The highest incidence of both external and internal voids was observed in the group using ZOE with the handheld lentulo spiral technique Conclusions Based on the findings of this study, for both filling materials, the handheld lentulo spiral technique had the greatest number of optimal lengths but there were also more voids.

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.

Effects of Access Cavity Design and Placement Techniques on Mineral Trioxide Aggregate Obturation Quality in Simulated Immature Teeth: A Micro-Computed Tomography Study

Background and Objectives: In teeth with open apices, performing single session apexification is a challenging treatment due to the difficulty in handling mineral trioxide aggregate (MTA). Minimally invasive approaches in dentistry have also influenced the cavity designs in endodontics. Until now, different techniques have not been investigated in addition to manual condensation during the process of placing MTA in traditional (TradACs) or conservative (ConsACs) endodontic access cavities. The aim of this in vitro study was to compare and evaluate the obturation quality of MTA apical plugs placed with different techniques in TradACs or ConsACs. Materials and Methods: Sixty upper central teeth were divided into two main groups based on cavity design, and then each main group was further divided into three subgroups according to MTA placement techniques (n = 10): TradAC-manual, TradAC-manual + indirect ultrasonic activation, TradAC-manual + XP-endo Shaper (XPS), ConsAC-manual, ConsAC-manual + indirect ultrasonic activation, and ConsAC-manual + XPS. Subsequently, the porosity percentages in the MTA apical plug were analyzed using micro-computed tomography. The statistical analysis was performed using the Kruskal-Wallis H test and Mann-Whitney U test. Statistical significance was set at p < 0.05. Results: There were differences in volume of porosity percentages (%) according to cavity designs and MTA application techniques (p < 0.05). Except for the XPS group, more porosity was observed in ConsACs compared to TradACs. In TradACs, the significantly lowest open and total porosity was observed in the manual, ultrasonic, and XPS techniques, respectively. In ConsACs, the significantly lowest porosity was observed in the manual, XPS, and ultrasonic techniques, respectively (p < 0.05). Conclusions: In MTA obturation, cavity designs and application techniques had an impact on the MTA porosity. Creating an apical plug in ConsACs may result in more porosity compared to TradACs, especially when manual or indirect ultrasonic activation is preferred. Opting for the manual technique alone may be considered sufficient for controlling porosity for both TradACs and ConsACs.

Micro-computed tomographic evaluation on the quality of single-cone obturation using a modified passive-deflation sealer injection needle: an in vitro study

OBJECTIVES

This study aimed to design a modified passive-deflation sealer injection needle and investigate its ability to improve obturation quality of single-cone technique through assessing the distribution of voids in root canals using micro-computed tomography (micro-CT).

MATERIALS AND METHODS

Forty-eight mandibular incisors were divided into eight groups (n = 6), according to the taper of root canal preparation (0.06 or 0.04), the needle used for sealer injection (modified or commercial iRoot SP injection needle), and the obturation method (iRoot SP sealer-only or single-cone obturation). After obturation, each specimen was scanned by micro-CT. The volumetric percentage and distribution of all voids were first analyzed and compared among groups, then the open and closed voids were separately analyzed and compared among single-cone obturation groups.

RESULTS

Compared to commercial needle groups, modified needle groups showed much less voids, especially in the apical root canal part (P < 0.05). Besides, the modified needle groups produced much less open voids than commercial needle groups despite the root canal taper (P < 0.05).

CONCLUSIONS

The modified passive deflation sealer injection needle could effectively improve the quality of single-cone obturation through reducing intra-canal voids, especially open voids throughout the root canal, thus might possibly be developed as an effective intra-canal sealer delivering instrument.

Effect of different sealer activation techniques on dentinal tubule penetration

The aim of this study was to evaluate the influence of different activation techniques on dentin tubule penetration of root canal sealer. Seventy-five teeth with single canals were chemomechanically prepared. A calcium silicate-based sealer was stained with a fluorescent dye (rhodamine B), placed into the canals and activated according to the following groups: control (no activation), EDDY, EndoActivator, ultrasonic and XP-Endo Finisher. Then, the samples were obturated. The percentages of sealer penetration at various depth levels of root sections were measured with confocal laser scanning microscopy. XP-Endo Finisher presented the highest penetration at 50 μm (p < 0.05). XP-Endo Finisher showed similar penetration with EDDY at 100 and 200 μm (p > 0.05) while presented higher penetration than the other groups (p < 0.05). At 500 μm, XP-Endo Finisher presented higher penetration than EndoActivator (p < 0.05) while similar penetration with the other groups (p > 0.05). XP-Endo Finisher can be recommended for activation during sealer placement for better penetration into dentin tubules.

Marginal gaps and voids using two warm compaction techniques and different sealers: a micro-CT study

OBJECTIVE

To assess the percentage of marginal gaps and voids in oval-shaped canals obturated by using two warm compaction techniques with a Bio-C sealer and AH Plus Jet.

MATERIALS AND METHODS

Forty canines with oval canals were scanned by microcomputed tomography (micro-CT), and root canal preparation was performed with an XP-endo Shaper system and irrigated with 5.25% sodium hypochlorite. Then, the specimens were paired into four groups (n=10) according to the root canal filling technique and endodontic sealer: Bio-C sealer and continuous wave of condensation, Bio-C sealer and Tagger's hybrid, AH Plus Jet and continuous wave of condensation, and AH Plus Jet and Tagger's hybrid. After root canal filling, a new scan was performed. The percentage of marginal gaps and voids was calculated with the ImageJ software, and the data were analyzed statistically using two-way ANOVA and Tukey tests, with a significance level of 5%.

RESULTS

The percentage of marginal gaps was significantly lower in the Bio-C sealer than in AH Plus Jet (p=0.021) regardless of the technique. However, no difference was found in the percentage of voids between root canal filling techniques and the endodontic sealer (p>0.05).

CONCLUSION

Both sealers and techniques demonstrated good quality of root canal filling. However, the use of the Bio-C sealer enhanced the filling ability by reducing marginal gaps, regardless of the root canal filling technique.

CLINICAL RELEVANCE

This study highlights the better performance of the Bio-C sealer in the quality of the root canal filling, reducing marginal gaps when compared to AH Plus Jet independent of the technique.

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.

Retreatability of calcium silicate-based root canal sealer using reciprocating instrumentation with different irrigation activation techniques in single-rooted canals

This study analysed the bioceramic sealer cleaning ability of two chemo-mechanical systems in intact and restored teeth. Thirty-two single-rooted teeth were used, and half of them restored with a pre-endodontic composite restoration (PCR). All samples were instrumented with a size 40 Reciproc Blue file and filled with BioRoot RCS. Canals were retreated using the R40 and then R50 Reciproc Blue. The samples were divided into four experimental groups (n = 8): intact teeth/passive ultrasonic irrigation (PUI) (G1), intact teeth/shock wave-enhanced emission photoacoustic streaming (SWEEPS) (G2), PCR/PUI (G3) and PCR/SWEEPS (G4). The samples were scanned by micro-CT before and after retreatment, and the volume of remaining filling material was evaluated. The minor percentage of residues were observed in G2, with a volume of 0.447 ± 0.356% of the endodontic space (P < 0.001). The Reciproc/SWEEPS technique showed the better performance in intact teeth compared with PUI technique. Pre-endodontic restoration did not significantly affect the effectiveness of sealer removal.

Pilot Evaluation of Sealer-Based Root Canal Obturation Using Epoxy-Resin-Based and Calcium-Silicate-Based Sealers: A Randomized Clinical Trial

The purpose of this randomized controlled clinical trial was to assess the short-term clinical effectiveness of sealer-based root canal obturation using calcium-silicate-based sealer (CSBS) and epoxy-resin-based sealer (ERBS). A total of eighty patients (eighty teeth) were enrolled and seventy-two patients (seventy-two teeth) were randomly assigned into four different sealer groups: AH Plus (AH, Dentsply Sirona), ADseal (AD, Meta Biomed), CeraSeal (CS, Meta Biomed), or EndoSeal TCS (ES, Maruchi). At the first visit, root canal treatment was performed using ProTaper. Next, the NiTi file system and passive ultrasonic irritation was applied with 2.5% NaOCl. At the second visit, the teeth were obturated with a sealer-based obturation technique using the assigned sealer. The quality of filling obturation was evaluated with postoperative radiographs in terms of the presence of voids and sealer extrusion. The patients were recalled at 1-week, 1-month, and 3-month intervals, and pain levels were measured using visual analog scales (VAS), and clinical examination performed with percussion and palpation. Radiographs were also taken. The results were statistically compared by using the χ2 test or Fisher exact test. Among the 80 teeth included, 72 teeth received allocated intervention and 71 teeth were included in the analysis (98.6% recall). There was no significant difference among the sealers in void and sealer extrusion (p > 0.05). Postoperative pain was not indicated prominently regardless of the type of sealer. For a 3-month follow-up period, all cases were maintained successfully except for one case from AD. According to the findings, there was no significant difference between CSBS and ERBS in terms of postoperative pain or the healing process, and the variation in filling quality appears to be linked to the properties of each product.

The thermoplastic techniques or single-cone technique on the quality of root canal filling with tricalcium silicate-based sealer: An integrative review

Background

The filling of the root canal system (RCS) is an important step in endodontic treatment and aims to obtain a three-dimensional sealing of the root canal spaces to prevent bacterial contamination. For this, the selection of an appropriate sealer must be performed synchronously with the choice of the root canal filling technique. This study aims, through an integrative review, to evaluate the quality of root canal filling by comparing thermoplastic and single-cone (SC) techniques.

Material and Methods

The Medline/PubMed, Scopus, Web of Science and Virtual Health Library (VHL) databases were used to find articles published until November 2021. The eligibility criteria comprised articles that evaluating the quality of root canal filling comparing thermoplastic techniques with the SC technique using tricalcium silicate-based sealer. Studies that evaluated primary teeth, endodontic retreatment or perforations, different outcomes, and studies that considered artificial teeth or different sealer and material for obturation of different techniques were excluded. For articles that were not available for access, an additional contact with authors were considered. A total of 1699 articles were found. After duplicate removal, the title and abstract of 828 articles were screened. Sixteen articles were considered for full-text analysis, but only ten articles met the eligibility criteria. Data extracted from the studies were discussed and tabulated to allow the comparison of desired factors.

Results

Concerning the formation of gaps/voids, the thermoplastic techniques showed better results than the SC technique in 3 articles. On the other hand, 2 articles reported no statistical difference between the tested techniques. In addition, about the penetration of tricalcium silicate-based sealer in the dentinal tubules, of the 5 articles selected, in 4 there was no significant difference between the tested techniques and only one study showed better penetration of the sealer when using thermoplastic techniques.

Conclusions

The thermoplastic technique was better in most selected studies regarding gaps and voids, but regarding the penetration of the sealer into the tubules, both techniques were effective.

Key words:Root canal filling, thermoplastic techniques, tricalcium silicate.

The Effect of Sealer Application Methods on Voids Volume after Aging of Three Calcium Silicate-Based Sealers: A Micro-Computed Tomography Study

During obturation, air voids are undesirable as they may provide shelter for microorganisms or passage for fluids. This study aimed to compare the occurrence of voids between three calcium silicate-based sealers (CSBSs) (MTA-Fillapex, BioRoot-RCS, Bio-C) and the change in their volume after aging. In addition, we aimed to compare voids when using two sealer application methods: lentulo-spiral (LS) and gutta-percha (GP) cone. Thirty extracted mandibular premolars (n = 30) were endodontically prepared and obturated using single GP cone (SGPC) technique. Each sealer was applied to 10 teeth (n = 10) using LS or GP. Micro-computed tomography (micro-CT) was used to quantify the volume of root filling and voids before and after 8-week storage in a phosphate-rich medium. The percentage of root filling and voids were compared between the groups using a Mann–Whitney U test and Kruskal–Wallis test with a Bonferroni correction. Before aging, the percentages of root filling volume after obturation were comparable with no significant differences between sealers (p = 0.325) or application methods (p = 0.950). After aging, the voids’ volume increased significantly in all sealers (p ≤ 0.05). However, no significant differences were found between sealers (p = 0.302). In conclusion, voids in CSBSs may not reduce in size with aging; hence, SGPC should be carefully selected for suitable cases.

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.

Removal of Accumulated Hard Tissue Debris (AHTD) from Root Canals with an Electric Current Device: A MicroCT Preliminary Report

In modern endodontics, removal of accumulated hard tissue debris (AHTD) from root canals is requested. In the last decade, different irrigating solutions and activation methods have been successfully tested. Sonic activation has been shown to be effective in the removal of AHTD. Electric current has been tested before in restorative dentistry, but not in endodontics. An experimental electric current delivering device was compared in the removal of AHTD, using microCT analyses. Fifteen single-rooted teeth were shaped with TruNatomy system endodontic files and divided into three groups: negative control group: specimens underwent no activation; EA group: specimens were activated with EndoActivator (EA); EB group: specimens were activated with ElectroBond (EB). The 2D images, 3D images and morphometric analysis from the microCT showed a statistically significant increased AHTD removal when EB was used. Results of the present preliminary study showed that the irrigant activation with ElectroBond is encouraging when compared to EndoActivator along the entire root canal system. The AHTD was significantly statistically reduced, validating the clinical use of electric fields in endodontics.

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.

Comparison of Obturation Quality between Calcium Silicate-Based Sealers and Resin-Based Sealers for Endodontic Re-treatment

BACKGROUND

The objective of this micro-computed tomography (micro-CT)-based study was to compare the filling quality of endodontic treatment and endodontic Re-treatment between two sealers with matched obturation techniques: calcium silicate-based sealer (Endoseal TCS) with a single-cone technique (SCT) and resin-based sealer (AH Plus) with a continuous wave technique (CWT).

METHODS

Forty maxillary premolars were selected and assigned into four groups, according to the obturation methods of the first endodontic treatment and Re-treatment (n = 10). The AP/AP group was first treated with AH Plus/CWT, then re-treated with AH Plus/CWT. The AP/ET group was first treated with AH Plus/CWT, then re-treated with Endoseal TCS/SCT. The ET/AP group was first treated with Endoseal TCS/SCT, then re-treated with AH Plus/CWT, and the ET/ET group was first treated with Endoseal TCS/SCT, then re-treated with Endoseal TCS/SCT. The specimens were scanned using micro-CT at three time points: after the first endodontic treatment, after gutta-percha (GP) cone removal, and after Re-treatment. The void volume of root canal obturation and the volume of the remaining filling materials were calculated. Data were analyzed using Student's t-tests and ANOVA.

RESULTS

The Endoseal TCS groups (ET/AP and ET/ET) showed a lower percentage of voids than the AH plus groups (AP/AP and AP/ET) on the whole canal and the apical third, after first obturation (p < 0.05). The AH plus group showed significantly fewer remnants than the Endoseal TCS group after GP removal (p < 0.05). Re-treated canals and initially treated canals had similar void volumes (p > 0.05). There was no significant difference in void volume after Re-treatment, regardless of whether the same or different sealers were used for the first treatment and Re-treatment (p < 0.05).

CONCLUSIONS

Endoseal TCS sealer and AH Plus sealer had a similar Re-treatment efficacy, regardless of which sealer was used in the previous treatment.

Void characteristics and tortuosity of calcium silicate-based cements for regenerative endodontics: a micro-computed tomography analysis

Background

Internal voids of materials can serve a hub for microorganism and affect the sealing ability. This study aimed to evaluate the sealing performance of calcium silicate-based cements in immature teeth treated with regenerative endodontics.

Methods

Twenty single root canals from immature permanent premolars were prepared using regenerative endodontic protocols. The root canals were randomly divided into two groups and sealed with mineral trioxide aggregate (MTA) and Biodentine (BD). The teeth were kept in humid environment for 7 days and scanned using micro-computed tomography. The voids within the cements were segmented and visualized using image processing, incorporating the modified Otsu algorithm. The porosity of each sample was also calculated as the ratio between the number of voxels of voids and the volume of the cements. Tortuosity was also calculated using the A-star algorithm.

Results

Voids larger than 70 μm were predominantly observed in the top and interfacial surface of cements. The others were evenly distributed. MTA and BD showed the same level of porosity and tortuosity at interfacial surfaces. In inner surfaces, MTA showed more less porosity and tortuosity compared to BD (p < 0.05).

Conclusions

There were no differences in sealing performance between MTA and BD.

Comparison of Root Filling Quality of Two Types of Single Cone-Based Canal Filling Methods in Complex Root Canal Anatomies: The Ultrasonic Vibration and Thermo-Hydrodynamic Obturation versus Single-Cone Technique

This study aimed to assess the effectiveness of ultrasonic vibration and thermo-hydrodynamic obturation (VibraTHO) using two types of root canal sealers, in comparison to the single-cone (SC) technique and a calcium silicate-based root canal sealer in complex root canal anatomies. Thirty single-rooted human maxillary premolars with two canals that had a complex root canal anatomy of transverse anastomoses or ramifications were prepared and assigned to the following three experimental groups, according to the filling method: SE group, SC technique with Endoseal TCS; VE group, VibraTHO with Endoseal TCS; and VG group, VibraTHO with GuttaFlow 2. Each tooth was scanned using micro-computed tomography, and the volume percentages of the filling material were calculated. The analysis of variance was used to analyze the statistical differences between the three groups (p < 0.05). The mean volume of the filling material was higher in the VG and VE groups than that in the SE group (p < 0.05) along the apical to middle-to-coronal thirds, and significant differences were observed between each root canal area (p < 0.05), with the only exception being at the apical thirds between the VE and SE groups. The VibraTHO technique using GuttaFlow 2 can be a more effective root canal filling method for anatomically complex root canal systems than the SC technique with Endoseal TCS. On the other hand, the VibraTHO technique using Endoseal TCS has a limited effect on improving the quality of the root filling at the apical portion of anatomically complex root canal systems, compared to the SC technique with Endoseal TCS.

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.

Evaluation of the sealer/gutta-percha ratio on sets of root section surfaces of some extracted teeth sealed using the cold lateral condensation technique

Canal filling must be well adapted to the walls of the root canal to prevent bacterial infiltration. Endodontic seals play an essential role in ensuring tightness, without which the canal filling would suffer infiltrations. This study aimed to evaluate the areas occupied by the two components of the canal filling, as well as the sealer/gutta-percha ratio in the root canals of the maxillary central incisors after their filling using the cold lateral condensation technique with gutta-percha. Thirty extracted upper central incisors were rotatably prepared with ProTaper Universal up to F3 and sealed using the cold lateral condensation technique with gutta-percha. After setting the sealer, the roots of the teeth were sectioned perpendicularly to 1 (L1), 3 (L3), 6 (L6), and 8 (L8) mm from the apex. The surface of the sections was analyzed with a Leica EZ4D stereomicroscope and photographed at two magnification orders: 10x and 25x. The areas corresponding to the gutta-percha, sealer, gaps, and root canal were expressed in pixels using the ImageJ software, version 1.50i. The difference in the representation of sealer areas, gutta-percha and voids was statistically significantly different for all four sections analyzed. The best adaptation of the canal obturation was observed in L1 and L3. The gutta-percha area was statistically significantly higher than that of the sealer for the L1, L3, and L6 levels, while the sealer/gutta-percha ratio recorded the lowest value at the L3 level (0, 30) and the highest at its L8 (0.70) level, without registering statistically significant differences regarding the area at the four analyzed levels. The voids were mostly absent or recorded a minimal percentage area (<1%). Cold lateral condensation of gutta-percha has led to a good adaptation of gutta-percha to the root canal wall, with a small amount of sealer, especially to the sections made at 3 mm from the apex. Given the limitations of this study, we noted that the voids were few – observed in the 6 and 8 mm sections – and were negligible in many cases.

Volume Percentage of Filling Voids in Root Canals Prepared by a Novel Nickel-Titanium Rotary System (TruNatomy) Using Two Different Obturation Techniques

This study aimed to compare the volume percentage of filling voids in root canals prepared with a newly introduced rotary system, TruNatomy (Dentsply Maillefer), and obturated by the modified continuous wave (CW) or single cone (SC) filling technique. Plastic tooth models with four canals were enlarged by using TruNatomy files and randomly allocated into either the CW or SC group. The volume percentage of filling voids at 1–6 mm from the apex was analyzed by using microcomputed tomography; mean values were compared by using independent two-sample t-tests (p < 0.05). The mean volume percentages of the filling voids were 2.81 ± 1.11% and 1.77 ± 0.82% in the CW and SC groups, respectively. In the apical area (1–4 mm), volume percentages in the palatal were significantly different between the CW and SC groups; in the middle area (4–6 mm), volume percentages in the palatal and the second mesiobuccal canals were significantly different (p < 0.05). The SC group showed lower volume percentages of filling voids than the CW group. The canals prepared by the TruNatomy system can be obturated well by both the SC and CW techniques. The SC technique showed a lower number of voids, especially in the palatal canals.

Ultrasonic vibration and thermo-hydrodynamic technique for filling root canals: Technical overview and a case series

AIM

To present a novel root canal filling technique: Ultrasonic Vibration & Thermo-Hydrodynamic Obturation (VibraTHO), and its rationale with a series of cases.

SUMMARY

The VibraTHO technique was used to fill the root canals of three clinically challenging cases: A C-shaped mandibular molar with complex anatomy, a C-shaped mandibular molar with an infected root canal system and a periapical lesion that required retreatment, and apically bifurcating mesiobuccal canals with a common orifice in a maxillary second molar. The cases were followed up for 15, 7 and 37 months, respectively. After follow-up, normal periapical status was observed without any noticeable radiographic change in the root canal fillings in each case. Periapical radiographs revealed complete healing of the periapical area in cases with pre-operative periapical lesions.

Presence of voids after three obturation techniques in band-shaped isthmuses: a micro-computed tomography study

Background

The objective of the present micro-computed tomography (micro-CT) study was to assess the presence of voids in band-shaped isthmuses obturated using three different filling techniques.

Methods

Twenty-four artificial molar teeth with a band-shaped isthmus were allocated to three groups (n = 8) for obturation, according to the filling technique: single-cone (SC), continuous wave of condensation (CWC) or lateral condensation (LC). Obturation was performed with gutta-percha (GP) cones and iRoot SP (Innovative Bioceramix, Vancouver, Canada). Post-filling micro-CT scanning was performed. The percentage of filling materials and void volumes were calculated in the isthmus areas and data were analyzed using one-way ANOVA and Tukey tests.

Results

The mean percentage of void volumes and corresponding filling percentages in the isthmus areas after obturation in the SC groups was 22.98 % ± 1.19 %, 77.02 % ± 1.19 %; in the CWC groups 10.46 % ± 2.28 %, 89.54 % ± 2.28 %; and in the LC groups was 13.14 % ± 1.85 %, 86.86 % ± 1.85 %, respectively.

Conclusions

In band-shaped isthmus area, the obturation quality of CWC was superior to SC and LC techniques.

Comparison of Obturation Quality after MTA Orthograde Filling with Various Obturation Techniques

This study aimed to quantify and compare the obturation quality after mineral trioxide aggregate (MTA) orthograde fillings with three different obturation techniques. Thirty-three extracted human maxillary molars were collected. Distobuccal and palatal canals were prepared to an apical size of #40/06 with a Profile Ni-Ti system. All 66 canals were divided into two groups according to the material (EZ-seal or OrthoMTA) and then obturated using three different techniques: manual compaction using S-kondenser (group H), compactor activation (group C), or reverse rotary motion of Ni-Ti file (group R). The obturated roots were scanned using micro-computed tomography (micro-CT). The percentage of voids located in the apical 5 mm was measured separately, that is, closed, open, and total porosity. There was no relation between the filling material and obturation technique (p > 0.05). The percentage volume of open and total porosity was higher in EZ-seal than in OrthoMTA (open: p = 0.002, total: p = 0.001). Group H showed higher open and total porosity than groups C and R. Micro-CT analysis showed that the void volume after orthograde MTA fillings significantly decreased when the additional activation was accompanied by hand condensation. Obturation with a Ni-Ti file using reverse motion could be recommended as an MTA orthograde filling technique.

Contribution of XP-Endo files to the root canal filling removal: A systematic review and meta-analysis of in vitro studies

This review was designed to analyse whether the supplementary use of XP-Endo Finisher and XP-Endo Finisher R contributes to the removal of root canal filling materials. Databases were searched up to November 2020. Studies were critically assessed according to inclusion and exclusion criteria. Risk of bias evaluation was performed. Pooled standardised mean differences (SMD) and 95% confidence intervals (95% CI) were calculated. Ten studies involving 192 teeth were eligible for systematic review and meta-analysis could be performed with eight of these studies. Strong evidence showed that XP-Endo Finisher R file contributed significantly to filling material removal from root canals (SMD (95% CI): 0.41 (0.06-0.76)). Although the evidence was conflicting, XP-Endo Finisher R file was superior than other irrigant activation techniques (SMD (95% CI): 0.47 (0.02-0.93)). The supplementary use of XP-Endo Finisher and XP-Endo Finisher R is beneficial in further removal of root canal filling materials from root canal system.

Effects of Ultrasonic Activation on Root Canal Filling Quality of Single-Cone Obturation with Calcium Silicate-Based Sealer

Background: We evaluated the effects of ultrasonic activation on root canal filling quality of the single-cone (SC) obturation technique with calcium silicate sealers and gutta percha cones. Methods: Thirty-six human single-rooted premolars were obturated with gutta percha and sealer. For the continuous wave (CW) group (n = 12), AH Plus with a continuous wave technique was used. The SC group (n = 12) received EndoSequence BC sealer with a single-cone technique. The SCU (SC with the addition of ultrasonic activation) group (n = 12) received the same treatment. Micro-computed tomography was used to scan the teeth, and the void volume within the root canal was evaluated at the apical, middle, and coronal levels. Then cross-sections were observed under a light microscope and scanning electron microscope (SEM). Results: Void volume was significantly lower in the SCU group than in the CW and SC groups. There were no statistically significant differences between the CW and SC groups. The SCU group had fewer voids than the CW and SC groups in the coronal and middle third areas. Specimens showed no apparent gaps or voids in any group. SEM images revealed both gap-free and gap-containing regions at different levels in all groups. Conclusions: Single-cone obturation with calcium silicate-based sealers might obtain enhanced filling quality when used with ultrasonic activation.

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.

Effect of obturation technique using a new bioceramic sealer on the presence of voids in flattened root canals

The aim of this study was to evaluate the filling ability of a new ready-to-use calcium silicate-based sealer using thermoplastic or single-cone technique in flattened root canals. Twenty-four flattened distal canals of mandibular molars with a buccolingual diameter 4 or more times larger than the mesiodistal diameter were selected. The root canals were prepared and filled (n = 12), according to the following techniques: thermoplastic or single-cone technique using Bio-C Sealer. The teeth were scanned using Skycan 1176 micro-computed tomography (micro-CT) - voxel size 8.74 µm, before and after filling the root canal. The percentage of voids in the filled root canals was evaluated, and the data were statistically analyzed using the unpaired t-test (α = 0.05). The root canals filled using the thermoplastic technique created a smaller percentage of voids in the cervical/middle thirds than those filled using the single-cone technique (p < 0.05). There was no difference in the percentage of voids using either technique in the apical third (p > 0.05). The flattened root canals in the cervical/middle thirds were better filled using the ready-to-use calcium silicate-based sealer associated to the thermoplastic technique, compared with the single-cone technique. In the apical third, the techniques showed similar filling ability.

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.

Micro-CT evaluation of filling of flattened root canals using a new premixed ready-to-use calcium silicate sealer by single-cone technique

The aim of this study was to evaluate the filling ability of a new premixed ready-to-use calcium silicate-based sealer, in comparison with an epoxy resin-based sealer by the single-cone technique in flattened root canals. Thirty-two flattened root canals of maxillary second premolars with buccal-lingual diameter 4 or more times larger than the mesio-distal diameter at 9 mm from the radiographic apex were selected. Root canals were prepared using Hyflex EDM 25/0.08 and additional preparation with ultrasonic tip Flatsonic and ProDesign Logic 25/0.03. After preparation, the root canals were filled with two root canal sealers (n = 16): Bio-C Sealer or AH Plus using the single-cone technique. Scanning was performed before and after root canal obturation using a Skycan 1176 micro-computed tomography (micro-CT) with an isotropic voxel size of 8.74 μm. The percentage of voids was analyzed in the cervical/middle thirds and in the apical third. Data were submitted to the Mann-Whitney test at a significance level of 5%. There was no statistical difference between Bio-C Sealer and AH Plus (p > .05). The percentage of voids in the cervical/middle thirds was 8.94% (1.33-39.95) for Bio-C Sealer and 9.30% (1.19-18.00) for AH Plus (p > .05). In the apical third, this percentage was 11.84% (4.85-27.00) for Bio-C Sealer and 9.21% (1.34-28.78) for AH Plus (p > .05). By using the single-cone technique, neither Bio-C Sealer nor AH Plus provided a voids-free root canal filling. Both sealers had similar filling ability in flattened root canals.

Filling ability of three variants of the single-cone technique with bioceramic sealer: a micro-computed tomography study

The present study evaluated the quality of single-cone root canal fillings with bioceramic (BC) sealer using three different techniques by means of micro-computed tomography (micro-CT). The canals of 30 extracted single-rooted permanent teeth were shaped with R40 Reciproc blue files and filled with the single-cone technique (SCT). BioRoot RCS BC sealer was placed inside the canals with one of the following master cones: R40 cone to working length (RWL, n = 10); R40 cone trimmed 1 mm short of working length (RWL-1, n = 10); non-standardized gutta-percha cone to working length (NSWL, n = 10). A quantitative and qualitative micro-CT analysis assessed the filling quality and internal/external voids formation. Collected data underwent statistical analysis by multivariate one-way analysis of variance (α = 0.05). In all groups, the voids were minimal and prevalently external. The NSWL and RWL-1 groups had increased sealer ratios in the whole canal and the apical canal portion, respectively. The lowest amounts of voids were found in the RWL group; the void volumes were slightly greater in the RWL-1 mm and NSWL groups, especially at the apical level. Two alternative SCTs showed satisfactory filling ability, uniform distribution of the BC sealer, and a minimally increased voids formation compared to the standard SCT with dedicated cone. The two tested alternative SCTs could take advantage of the beneficial characteristics of the BC sealer, which evenly filled the endodontic space, ideally sealing both the major and the accessory communications with the periodontium.

Root Canal Preparation and Enlargement Using Thermally Treated Nickel-Titanium Rotary Systems in Curved Canals

INTRODUCTION

The purpose of this study was to evaluate root canal preparation and apical enlargement of curved canals using rotary heat-treated and heat/surface-treated systems by micro-computed tomographic imaging.

METHODS

Curved mesial root canals (n = 48) of mandibular molars (20°-40°) were prepared using ProDesign Logic (PDL; Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) 25/.01 and 25/.06 or HyFlex EDM (HFEDM) 10/.05, HyFlex CM 20/.04, and HFEDM 25/.08. Apical enlargement was performed using PDL 40/.05 or HFEDM 40/.04. Scanning (9 μm) was performed before and after preparation and after apical enlargement using micro-computed tomographic imaging. Volume, percentage of volume increase, debris, untouched root canal surface, and centering ability were analyzed. Statistical analysis was performed using Mann-Whitney, Wilcoxon, and unpaired t tests (α = .05).

RESULTS

HFEDM promoted a higher volume increase of the root canals than PDL after preparation and after apical enlargement (P < .05). The apical enlargement promoted a significant decrease in debris and untouched surface in both groups (P < .05). The percentage of debris and untouched surface were similar between HFEDM and PDL after preparation and after apical enlargement (P > .05). Both systems promoted centered canals (P > .05).

CONCLUSIONS

HFEDM instruments promoted greater volume of the root canal than PDL. However, the cleaning ability of the instruments was similar. The apical increase up to size 40 with both instruments provided less debris and untouched surfaces and allowed centralization of the curved root canals.

Micro-computed tomography evaluation of root canal filling quality with apical negative pressure

OBJECTIVES

The objective of the present study was to compare, using micro-computed tomography (micro-CT), the location and volume percentage of voids in root canals that were obturated with a premixed tricalcium silicate sealer and a single gutta-percha master cone, in the presence or absence of apical negative pressure.

METHODS

Twenty extracted human mandibular premolars were cleaned and shaped. The teeth were assigned to 2 groups (n = 10) according to the filling technique: apical negative pressure sealer application combined with the single-cone technique (NPS) or syringe-assisted sealer application combined with the single-cone technique (SS). Each specimen was scanned using micro-CT at 10 μm resolution. The percentages of voids were calculated from segmental regions of interest. Data were analysed using nonparametric statistical methods, with statistical significance pre-set at α = 0.05.

RESULTS

Significant difference was identified (p < 0.05) in the overall percentage of voids between the NPS group (0.33 %; interquartile range 0.25 %) and the SS group (6.29 %; interquartile range 5.57 %). In the NPS group, the percentages of voids in the coronal-third or middle-third of the canal space were statistically lower than that in apical-third (p < 0.0167, Bonferroni adjustment), with no significant difference between the former two groups. In the SS group, no significant difference in the percentages of voids was identified among the coronal-third, middle-third and apical-third of the canal space.

CONCLUSIONS

Apical negative pressure sealer application combined with the single-cone technique produces fewer voids in root canal fillings than the conventional single-cone technique.

CLINICAL SIGNIFICANCE

The apical negative pressure sealer application technique combined with single-cone filling constitutes a novel root canal obturation technique that improves the quality of root canal filling by minimising the volume of voids within the three-dimensional canal space.

Immediate and Long-Term Porosity of Calcium Silicate-Based Sealers

INTRODUCTION

Open pores between endodontic sealer and root canal walls present potential niches for bacterial growth and migration pathways. The aim was to assess the internal and external porosity of calcium silicate-based sealers and to ascertain the long-term effect of storage in simulated body fluid on sealer porosity.

METHODS

Sixteen single-rooted teeth were filled with gutta-percha and 1 of 4 root canal sealers: BioRoot RCS, EndoSequence BC, MTA Fillapex, or AH Plus. Obturated roots, stored in Hank's balanced salt solution, were scanned after 7 days and after 6 months by using micro-computed tomography at an isotropic resolution of 9.9 μm. Total, open, and closed porosity were calculated in the coronal, middle, and apical thirds. Data were statistically analyzed by using general linear model and paired t test (α = 0.05).

RESULTS

Significantly higher percentage of open than closed porosity was found in all groups. Initially, significantly greater open and total porosity were found for MTA Fillapex than for AH Plus. After 6 months, the percentage of open and total porosity increased in BioRoot RCS and MTA Fillapex and decreased in AH Plus and EndoSequence BC. Both initially and after storage, coronal region of all sealers had significantly greater total porosity than middle and apical regions, which were comparable.

CONCLUSIONS

None of the root fillings were void-free, with predominant open porosity persisting after long-term storage.

Assessment of three Techniques in Surpassing Ledges in Curved Canals

The ledge formation is an iatrogenic accident that occurs in a curved canal due to the incorect application of the preparation techniques. The aim of this study was to find out which of the three well-known obturation techniques can surpass better an artificial created ledge. Matherials and methods: artificial ledge were created using Gates-Glidden drills no.1 and 2 at 15 mm and no.3 at 13 mm of the working lenght of fortyfour resin blocks. Thirty blocks that didn’t allowed a #10 file to surpass the ledge were accepted for study, divided into three equal groups and filled by lateral condensation, thermal compaction and continuous wave System B technique. Results: System B resulted in the highest obturated area beyond the starting point of the ledge (p<0,05), while lateral condensation showed the worst results. There were no differences between thermal compaction and lateral condensation in surpassing the deviation. Conclusion: within the limitation of this study, System B seems to be the the most appropriate techique when trying to surpass a ledge.

Effect of obturation technique with immediate and delayed post space preparation on apical voids and bond strength of apical gutta-percha

Objective

The purpose of this study was to evaluate the effect of immediate and delayed post space preparation on the sealing ability of two root canal obturation techniques by using micro-computed tomography imaging and a push-out test.

Methods

The root canals of 40 human maxillary premolar teeth were instrumented and divided into four groups: (A) single cone (SC) followed by immediate post space preparation, (B) continuous wave of condensation (CWC) followed by immediate post space preparation, (C) SC followed by delayed post space preparation, and (D) CWC followed by delayed post space preparation. Micro-CT scans were performed for volumetric analysis of voids and filling materials in the apical 4-mm portion. A push-out test was performed, and failure modes (adhesive, cohesive, or mixed) were assessed. Data were analyzed using the Kruskal-Wallis test and one-way analysis of variance.

Results

No significant differences were observed among the four groups in terms of the percentage volume of voids of the apical 4 mm or the bond strength of apical gutta-percha.

Conclusions

The percentage volume of voids and bond strength of apical gutta-percha were similar and were not significantly influenced by the timing of post space preparation or the obturation technique.

Micro-CT and nano-CT analysis of filling quality of three different endodontic sealers

OBJECTIVES

To investigate voids in different root canal sealers using micro-CT and nano-CT, and to explore the feasibility of using nano-CT for quantitative analysis of sealer filling quality.

METHODS

30 extracted mandibular central incisors were randomly assigned into three groups according to the applied root canal sealers (Total BC Sealer, Sure Seal Root, AH Plus) by the single cone technique. Subsequently, micro-CT and nano-CT were performed to analyse the incidence rate of voids, void fraction, void volume and their distribution in each sample.

RESULTS

Micro-CT evaluation showed no significant difference among sealers for the incidence rate of voids or void fraction in the whole filling materials (p > 0.05), whereas a significant difference was found between AH Plus and the other two sealers using nano-CT (p < 0.05). All three sealers presented less void volume in the apical third; however, higher void volumes were observed in the apical and coronal thirds in AH Plus using micro-CT (p < 0.05), while nano-CT results displayed higher void volume in AH Plus among all the sealers and regions (p < 0.05).

CONCLUSIONS

Bioactive sealers showed higher root filling rate, lower incidence rate of voids, void fraction and void volume than AH Plus under nano-CT analysis, when round root canals were treated by the single cone technique. The disparate results suggest that the higher resolution of nano-CT have a greater ability of distinguishing internal porosity, and therefore suggesting the potential use of nano-CT in quantitative analysis of filling quality of sealers.

Quantification of the tug-back by measuring the pulling force and micro computed tomographic evaluation

Objectives

The aims of this study were to quantify tug-back by measuring the pulling force and investigate the correlation of clinical tug-back pulling force with in vitro gutta-percha (GP) cone adaptation score using micro-computed tomography (µCT).

Materials and Methods

Twenty-eight roots from human single-rooted teeth were divided into 2 groups. In the ProTaper Next (PTN) group, root canals were prepared with PTN, and in the ProFile (PF) group, root canals were prepared using PF (n = 14). The degree of tug-back was scored after selecting taper-matched GP cones. A novel method using a spring balance was designed to quantify the tug-back by measuring the pulling force. The correlation between tug-back scores, pulling force, and percentage of the gutta-percha occupied area (pGPOA) within apical 3 mm was investigated using µCT. The data were analyzed using Pearson's correlation analysis, one-way analysis of variance (ANOVA) and Tukey's test.

Results

Specimens with a strong tug-back had a mean pulling force of 1.24 N (range, 0.15–1.70 N). This study showed a positive correlation between tug-back score, pulling force, and pGPOA. However, there was no significant difference in these factors between the PTN and PF groups. Regardless of the groups, pGPOA and pulling force were significantly higher in the specimens with a higher tug-back score (p < 0.05).

Conclusions

The degree of subjective tug-back was a definitive determinant for master cone adaptation in the root canal. The use of the tug-back scoring system and pulling force allows the interpretation of subjective tug-back in a more objective and quantitative manner.

Comparison of the Percentage of Voids in the Canal Filling of a Calcium Silicate-Based Sealer and Gutta Percha Cones Using Two Obturation Techniques

This study evaluated the root-filling quality of a calcium silicate-based sealer and gutta percha (GP) cones by measuring the percentage of voids. Twenty artificial molar teeth were divided into two groups: one obturated using the single-cone (SC) technique, and the other using the continuous wave (CW) technique. Obturation was performed with GP cones and Endoseal MTA (mineral trioxide aggregate, Maruchi, Wonju, Korea). Obturated teeth were scanned using microcomputed tomography, and the percentage of void volume was calculated in the apical and coronal areas. A linear mixed model was used to determine the differences between the two techniques (p < 0.05). The percentage of voids between the filling materials and root canal walls was not significantly different between the two obturation methods (p > 0.05), except for the CW group, which demonstrated a significantly higher void volume in the coronal area of the distal canal (p < 0.05). The percentage of voids inside the filling material was significantly higher in the CW groups for all of the comparisons (p < 0.05), except in the apical area of the distal canal (p > 0.05). The voids between the filling material and canal wall in the apical area were not significantly different between the two techniques.

Evaluation of physicochemical properties of root-end filling materials using conventional and Micro-CT tests

Objective

To evaluate solubility, dimensional stability, filling ability and volumetric change of root-end filling materials using conventional tests and new Micro-CT-based methods.

Material and Methods

7.

Results

The results suggested correlated or complementary data between the proposed tests. At 7 days, BIO showed higher solubility and at 30 days, showed higher volumetric change in comparison with MTA (p<0.05). With regard to volumetric change, the tested materials were similar (p>0.05) at 7 days. At 30 days, they presented similar solubility. BIO and MTA showed higher dimensional stability than ZOE (p<0.05). ZOE and BIO showed higher filling ability (p<0.05).

Conclusions

ZOE presented a higher dimensional change, and BIO had greater solubility after 7 days. BIO presented filling ability and dimensional stability, but greater volumetric change than MTA after 30 days. Micro-CT can provide important data on the physicochemical properties of materials complementing conventional tests.

In vitro comparison of gutta-percha-filled area percentages in root canals instrumented and obturated with different techniques

Purpose:

To evaluate the efficacy of different obturation techniques in root canals instrumented either by hand or rotary instruments with regard to the percentage of gutta- percha-filled area (PGFA).

Materials and Methods:

One hundred and sixty extracted mandibular premolars with single, straight root canals were studied. Root canals were prepared to an apical size of 30 by hand with a modified crown-down technique or the ProTaper and HEROShaper systems. Teeth were divided into eight groups (n=20) according to the following instrumentation and obturation techniques: G1: Hand files+lateral condensation (LC), G2: Hand files+Thermafil, G3: ProTaper+LC, G4: ProTaper+single-cone, G5: ProTaper+ProTaper-Obturator, G6: HEROShaper+LC, G7: HEROShaper+single-cone, G8: HEROShaper+HEROfill. Horizontal sections were cut at 1, 3, 5, 7, 9, 11 and 13 mm from the apical foramen. A total of 1120 sections obtained were digitally photographed under a stereomicroscope set at 48X magnification. The cross-sectional area of the canal and the gutta-percha was measured by digital image analysis and the PGFA was calculated for each section.

Results:

The mean of the PGFA in Thermafil (G2), ProTaper-Obturator (G5) and HEROfill (G8) groups was significantly higher than the other groups. In G3 and G4, PGFA showed no significant difference in the apical segments whereas PGFA was significantly higher at the middle and coronal segments in G3. In G6 and G7, PGFA showed no significant difference in the apical and middle segments whereas PGFA was significantly higher at the coronal segments in G6.

Conclusion:

The carrier-based gutta-percha obturation systems revealed significantly higher PGFA in comparison to single-cone and lateral condensation techniques.