Interfacial adaptation of an epoxy-resin sealer and a self-etch sealer to root canal dentin using the System B or the single cone technique

Effect of the Modified Methacrylate-Based Root Canal Sealer in Single-Cone Technique

This study aimed to modify EndoREZ with 2.5% dimethylaminododecyl methacrylate (DMADDM) and 1% magnetic nanoparticles (MNP) to study its sealing property, penetration and long-term antibacterial and therapeutic effect in the single-cone technique (SCT) compared with EndoREZ and iRoot SP. Thirty single-root human maxillary premolars were assigned into three groups and obturated with three different root canal sealers by SCT. Every specimen was then scanned using micro-CT to analyze void fraction, and void volumes and confocal laser scanning microscope (CLSM) was used to study the dentin penetration. The long-term antimicrobial effects were tested in vitro before and after aging 1 and 4 weeks by the single-strain Enterococcus faecalis biofilm model. In addition, the beagle canine model of apical periodontitis (AP) was utilized to judge and compare the therapeutic effect of three sealers in SCT. The void fraction and void volumes of the modified root canal sealer were not significantly different from iRoot SP (p > 0.05) but were lower than EndoREZ (p < 0.05). The modified root canal sealant displayed a greater penetration, long-term antibacterial property, and treatment effect than the other groups (p < 0.05). This indicated that after being modified with DMADDM and MNP, it showed better performance in SCT.

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.

Effect of post-space irrigation with acid solutions on bond strength and dentin penetrability using a self-adhesive cementation system

Background

The aim of this study was to evaluate the effects of surface treatments with 1% peracetic acid (PA), solution containing 17% EDTA (SmearClear, Kerr Endodontics), solution containing a combination of 17% EDTA with 2% chlorhexidine (QMix, Dentsply Sirona) on the post-space root dentin compared to 2.5% sodium hypochlorite (NaOCl) on bond strength and resin tags length in dentin.

Material and Methods

Forty human-canine roots were endodontically treated and the post space was prepared. The specimens were randomised into four groups (n = 10): control – irrigation with 2.5% NaOCl solution, PA – irrigation with 1% PA, SmearClear – irrigation with SmearClear solution, and QMix – irrigation with QMix solution. The fibre posts were cemented using a self-adhesive resin system (Relyx U200, 3M ESPE). After six months, the specimens were cross-sectioned and subjected to push-out and confocal laser microscopy tests. One-way ANOVA and Tukey’s tests were used to analyse the data (α= 0.05).

Results

PA and QMix presented the highest bond strength values compared to the other groups (p< 0.05). There was no significant difference between the resin tags length in dentin by the groups (p = 0.75).

Conclusions

Irrigation of the post space with 1% PA and QMix showed a positive clinical impact on the adhesion between the fiber post and root dentin. However, these materials had no influence on resin tags length in dentin by self-adhesive resin cement.

Key words:Fiber post, adhesive cementation, self-adhesive resin cement, root dentin, irrigating solutions.

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.

Quality of Root Canal Filling Using a Bioceramic Sealer in Oval Canals: A Three-Dimensional Analysis

Objectives  The oval canals may be associated with inadequate debridement, which can affect the quality of the root canal filling, thus the treatment outcome. The aim of the present work was to compare the quality of oval canals fillings using EndoSequence BC sealer with the single-cone technique or cold lateral compaction.

Materials and Methods  Thirty-eight human single-rooted premolars with oval canals were instrumented to 1 mm from the apical foramen with hand nickel–titanium files, followed by circumferential filing with Hedstrom files. Teeth were paired into two groups based on their micro-computed tomography (CT) morphological parameters. Both groups were filled using EndoSequence BC sealer. The first used a single cone and the other with the cold lateral compaction technique. The voids volume was evaluated by micro-CT and the percentage was calculated for the total length and for the apical 5 mm of each canal. The Mann–Whitney U test was used to assess whether the surface area and obturation length differed significantly between the groups and to compare the percentage of voids for each technique.

Results  Both techniques resulted in less than 16% voids, with no statistically significant difference between them for the total canal length and for the apical 5 mm ( p > 0.05).

Conclusions  The quality of the obturation performed with the single-cone technique was similar to that achieved with lateral compaction using EndoSequence BC sealer in oval canals.

Synthesis, Characterization, and Antibacterial Evaluation of a Cost-Effective Endodontic Sealer Based on Tricalcium Silicate-White Portland Cement

Mineral trioxide aggregate (MTA) is an ideal yet costly endodontic sealer material. Tricalcium silicate-white Portland cement (TS-WPC) seems to have similar characteristics to those of MTA. This work aims to characterize a modified TS-WPC and evaluate its antibacterial properties as a potential endodontic sealer material. The modified TS-WPC was synthesized from a 4:1 mixture of sterilized Indocement TS-WPC and bismuth trioxide using a simple solution method with 99.9% isopropanol. The mixture was stirred until it was homogenous, centrifuged, and dried. The material was then characterized using infrared spectroscopy, X-ray diffraction, and electron microscopy and subjected to antibacterial evaluation against Enterococcus faecalis using a Mueller-Hinton agar inhibition test. The results showed that the material was characterized by main functional groups of hydroxyls, silicate, bismuth trioxide, and tricalcium silicate, like those of a commercial MTA-based sealer, both tested after hydration. Modified TS-WPC before hydration showed similar powder morphology and size to the commercial one, indicating the ease of manipulation. Both materials exhibited antibacterial activity due to calcium dihydroxide's ability to absorb carbon dioxide, which is essential for the anaerobic E. faecalis, with minimum inhibitory effect and bactericidal concentrations of 12,500 ppm and 25,000 ppm, respectively. The modified TS-WPC has the potential to become a cost-effective alternative endodontic sealer material.

Warm Gutta-Percha Techniques Regulate Cell Viability, Heat Shock, and Mineralized Tissue-associated Proteins of Cementoblasts

INTRODUCTION

The aim of this study was to determine the effect of the continuous wave of condensation technique (CWCT) and the thermoplastic gutta-percha injection (TGI) technique on the messenger RNA (mRNA) expressions of heat shock proteins (HSPs) and mineralized tissue-associated proteins of the immortalized mouse cementoblasts (OCCM.30).

METHODS

Crowns of human premolar teeth with single and straight canals were removed. The root canals were prepared up to the ProTaper Next X5 file (Dentsply Maillefer, Ballaigues, Switzerland) in combination with 2 mL 2.5% sodium hypochlorite solution. Roots (12 ± 2 mm height) were sterilized (121°C for 20 minutes) and placed vertically to the cell culture dishes using a tissue culture insert by opening holes according to the root diameter after the removal of 1 mm from the apex for appropriate adaptation to the petri dish surfaces. Six groups were created: control 1 (without teeth), control 2 (with teeth), AH Plus (Dentsply DeTrey, Konstanz, Germany), single-cone obturation (SC), CWCT, and thermoplastic gutta-percha injection technique (TGI). The viability of the OCCM.30 cells was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell viability experiments at 24 and 96 hours. The mRNA expression of HSP27, HSP70, and HSP90 and mineralized tissue markers (bone sialoprotein, osteocalcin, runt-related transcription factor 2, type I collagen, and alkaline phosphatase) was evaluated by real-time polymerase chain reaction.

RESULTS

Reduced OCCM.30 cell viability was observed in all groups except the control groups. When the SC technique and CWCT and TGI groups were compared, it was observed that heat had a significant negative effect on cell viability (P < .05). A reduction in the mRNA expressions of HSP27, HSP70, and HSP90 was recognized in all test groups when compared with the control 1 group (P < .01). When the warm gutta-percha techniques were compared with the SC technique, a decrease in mRNA expression of HSP27 and HSP90 was noted (P < .01). The HSP70 transcript was similar in the CWCT group and the SC group. Higher HSP70 mRNA expression was observed in the TGI group compared with the SC group. In all groups except the control 1 group, bone sialoprotein, osteocalcin, runt-related transcription factor 2, type I collagen, and alkaline phosphatase mineralized tissue markers were affected, but this negative effect was higher in the heat-treated groups (P < .05).

CONCLUSIONS

Within the limitations of this study, it was concluded that warm gutta-percha techniques reduced the mRNA expressions of the genes for HSPs and mineralized tissue-associated proteins of cementoblasts. Further animal studies are needed to clarify the effect of heat on the behavior of cementoblasts histologically in short- and long-term periods.

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.

Oroactive dental biomaterials and their use in endodontic therapy

Dental biomaterials have revolutionized modern therapies. Untreated dental caries remains the major etiological factor for endodontic treatment, and together with a decreasing rate of tooth loss escalates the importance of continuously improving the materials used for endodontic therapies. Endodontic biomaterials are used for vital pulp therapies, irrigation, intracanal medicaments, obturation and regenerative procedures. These materials offer several functions including: antimicrobial activity, mechanical reinforcement, aesthetics, and therapeutic effects. Vital pulp therapies have seen an improvement in clinical results with an incremental approach to build on the strengths of past materials such as calcium hydroxide and calcium silicates. While sodium hypochlorite remains the gold standard for canal irrigation, numerous nanoparticle formulations have been developed to promote sustained antimicrobial action. Gutta-percha based bulk fillers remain the most common materials for root filling. However, while multiple studies focus on the development of novel formulations containing drugs, glass derivatives or ionic-, polymeric-, or drug- loaded nanoparticles, a lack of reliable and long-term clinical evidence obligates further study as experienced clinicians prefer to use what has worked for decades. This review delves in to the biochemistry of the materials to scrutinize their shortcomings, and where opportunity lies to further enhance their efficacy in endodontic practice. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:201-212, 2020.

Comparing the Ability of Different Materials and Techniques in Filling Artificial Internal Resorption Cavities

Objective

This ex vivo study aims to investigate the root filling quality of warm vertical technique, single-cone technique with GuttaFlow2, Endoseal MTA and EndoSequence BC sealer as a sealer in artificial internal resorption cavity.

Methods

For this study, 40 human single-root teeth were selected. After root preparation, the roots were horizontally sectioned 7 mm from the apex. The hemisphere cavities were created on both sides, and then they were re-approximated. According to filling methods and materials, the samples were randomly as-signed to four experimental groups: I: warm vertical compaction technique (WVC), II: single-cone technique with GuttaFlow2 (GF), III: single-cone technique with Endoseal MTA sealer (EM), IV: single-cone technique with EndoSequence BC sealer (ES). Filled roots were radiographed in buccolingual and mesiodistal views to check the obturation, and stored in humid environment at the room temperature for 7 days. Each tooth was sectioned 7 mm from the root apex at the level of the previous cut, and it was then photographed un-der stereomicroscope. The photographs and radiographs of all samples were imported to an image-analysis software to calculate the percentage of sealer, gutta-percha, and voids. The results were statistically analyzed using one-way ANOVA and Kruskal-Wallis Dunn's tests.

Results

In buccolingual view of radiographs, the WVC and EM groups showed significantly lower percent-age of voids (P value<0.05) compared to that in the GF group. In mesiodistal view, the WVC and EM groups showed significantly lower percentage of voids (P value<0.05) compared to that in the GF and ES groups. In stereomicroscope evaluation, the WVC and EM groups showed significantly lower percentage of voids (P value<0.05) compared to that in the GF and ES groups. The differences observed between the WVC and EM groups (P value>0.05) or between the GF and ES groups (P value>0.05) were not significant.

Conclusion

WVC technique and single-cone technique with EM sealer are the optimum methods to fill ar-tificial resorption cavities.

Comparison of microtomography and optical coherence tomography on apical endodontic filling analysis

OBJECTIVES

To comparein vitro differences in the apical filling regarding working length (WL) change and presence of voids and to validate optical coherence tomography (OCT) in comparison with computerized microtomography (µCT) for the detection of failures in the apical filling.

METHODS

Forty-five uniradicular teeth with round canals, divided into groups (n = 15) following the obturation protocols: LC (lateral condensation), TMC (thermomechanical compaction) and SC (single cone). Samples were scanned using µCT (parameters: 80 kV, 222 µA, and resolution of 11 µm), OCT (parameters: SSOCT, 1300 nm and axial resolution of 12 µm), and periapical digital radiography. The images were analyzsed by two blind and calibrated observers using ImageJ software to measure the boundary of the obturation WL and voids presence. Categorical and metric data were submitted to inferential analysis, and the validity of the OCT as a diagnostic test was assessed with performance and reliability tests.

RESULTS

The WL average remained constant for all obturation techniques and image methods. OCT showed adequate sensitivity and specificity to detect voids in the WL of apical obturations in vitro in comparison with µCT. Both image methods found a higher number of voids for LC technique (µCT p = 0.011/OCT p = 0.002).

CONCLUSIONS

OCT can be used in apical obturation voids assessment and the LC technique revealed more voids with larger dimensions.

The Tubular Penetration Depth and Adaption of Four Sealers: A Scanning Electron Microscopic Study

Background. The tubular penetration and adaptation of the sealer are important factors for successful root canal filling. The aim of this study was to evaluate the tubular penetration depth of four different sealers in the coronal, middle, and apical third of root canals as well as the adaptation of these sealers to root canal walls. Materials and Methods. 50 single-rooted teeth were prepared in this study. Forty-eight of them were filled with different sealers (Cortisomol, iRoot SP, AH-Plus, and RealSeal SE) and respective core filling materials. Then the specimens were sectioned and scanning electron microscopy was employed to assess the tubular penetration and adaptation of the sealers. Results. Our results demonstrated that the maximum penetration was exhibited by RealSeal SE, followed by AH-Plus, iRoot SP, and Cortisomol. As regards the adaptation property to root canal walls, AH-Plus has best adaptation capacity followed by iRoot SP, RealSeal SE, and Cortisomol. Conclusion. The tubular penetration and adaptation vary with the different sealers investigated. RealSeal SE showed the most optimal tubular penetration, whereas AH-Plus presented the best adaptation to the root canal walls.

Micro-CT assessment of the sealing ability of three root canal filling techniques

This study used micro-CT to compare three obturation techniques with respect to void occurrence in canals filled with bioceramic sealer. Thirty extracted first mandibular premolars were prepared with a ProTaper Universal system and randomly allocated to three groups. Canals were obturated with gutta-percha and bioceramic root canal sealer, using either single-cone, lateral compaction, or Thermafil filling technique. Each tooth was then scanned with micro-CT. Voids in 2D cross-sectional images and void volumes in 3D images of all root thirds were assessed in relation to obturation technique. There was no significant difference between obturation techniques in the proportion of sections with voids (P > 0.05). However, the results of the obturation techniques significantly differed in relation to root region (P < 0.05). In conclusion, no root filling technique resulted in void-free specimens. Void volumes were highest for the single-cone technique and lowest for Thermafil, in all regions (P < 0.05).

Evaluation of root canal sealer filling quality using a single-cone technique in oval shaped canals: An In vitro Micro-CT study

The aim of this study was to evaluate and compare the presence of voids in oval root canals filled with different root canal sealers (EndoSequence BC Sealer, Smartpaste bio, ActiV GP) and to compare those with root canals filled with AH Plus sealer using micro-CT. In total, 40 freshly extracted human single-root maxillary premolars were used. Specimens instrumented with the EndoSequence NiTi rotary instrument were assigned randomly into four groups. In each group, root canals were filled with single-cone gutta-percha and one of the tested sealers. Each specimen was then scanned using micro-CT at a voxel resolution of 13.47 μm. Proportions of sections with voids in cross-sectional images and void volumes for each sealer were calculated in the apical, middle, and coronal thirds. Differences according to root canal sealers were evaluated statistically using the Kruskal-Wallis test and the Mann-Whitney U-test at a significance level of 5%. The analysis showed a decrease in void formation in the apical third, with a significant difference between the apical and coronal thirds among bioceramic sealers, ActiV GP, and AH Plus (p < 0.05) but no significant difference between the apical and middle thirds or between the middle and coronal thirds was found for the sealers tested (p > 0.05). All root canal sealers tested resulted in voids. The bioceramic sealers (EndoSequence BC Sealer, Smartpaste bio) produced similar voids which had the fewest in the apical third of root canals among the sealers tested which can be related due to root canal anatomy variations.

Influence of Sealer Placement Technique on the Quality of Root Canal Filling by Lateral Compaction or Single Cone

The aim of this study was to evaluate the influence of the sealer placement technique on the quality of root canal filling using Lateral Compaction (LC) or Single Cone (SC). In order to do that, 60 mesial roots of mandibular first molars were prepared and divided into 2 groups (n=30), according to the filling technique: LC and SC. Each group was subdivided into 3 subgroups (n=10), according to the different sealer placement methods: A: Master gutta-percha (GP) cone; B: Lentulo spiral; C: File. The roots were sectioned at 2, 4 and 6 mm from the apex and photographed with the aid of a digital microscope. Then, areas of GP, endodontic sealer and voids were measured, and these data were subjected to statistical analysis. LC technique showed no statistically difference (p>0.05) in the percentage of GP area, sealer and voids between the subgroups at any of the three levels. After use of SC, higher percentages of sealer area were found at all levels (p<0.01) when the sealer was placed with a file. At 2 mm, higher percentage of void areas (p<0.05) was observed when the cone was used, lower percentage with K-file and the lowest percentage with Lentulo. At 4 mm, cone showed higher percentage of void areas (p<0.05). At 6 mm, there were no significant differences (p>0.05) between the three methods. Considering these results, using an instrument for sealer placement was important in the SC technique to reduce voids. Regarding LC, the sealer placement techniques provided similar results.

Ability of new obturation materials to improve the seal of the root canal system: a review

New obturation biomaterials have been introduced over the past decade to improve the seal of the root canal system. However, it is not clear whether they have really produced a three-dimensional impervious seal that is important for reducing diseases associated with root canal treatment. A review of the literature was performed to identify models that have been employed for evaluating the seal of the root canal system. In vitro and in vivo models are not totally adept at quantifying the seal of root canals obturated with classic materials. Thus, one has to resort to clinical outcomes to examine whether there are real benefits associated with the use of recently introduced materials for obturating root canals. However, there is no simple answer because endodontic treatment outcomes are influenced by a host of other predictors that are more likely to take precedence over the influence of obturation materials. From the perspective of clinical performance, classic root filling materials have stood the test of time. Because many of the recently introduced materials are so new, there is not enough evidence yet to support their ability to improve clinical performance. This emphasizes the need to translate anecdotal information into clinically relevant research data on new biomaterials.

Influence of the Method in Root Canal Filling Using Active Lateral Compaction Techniques

The aim of this study was to evaluate, by stereomicroscopy and confocal laser microscopy, the influence of different lateral compaction methods for the obturation quality, as well as the time spent for the procedure. Thirty root canals of freshly extracted single-rooted human teeth were prepared with the ProTaper system up to F5 instrument and filled with gutta-percha and AH Plus sealer by the lateral compaction technique. The teeth were divided into 3 groups (n=10) in accordance with the method used for the lateral compaction, as follows: Manual, Mechanical and Ultrasonic. The sealers were stained with rhodamine B dye in a proportion of 0.1% per gram in weight to allow for the analysis under a confocal microscope. During the root filling procedure, the time spent was recorded with a stopwatch. The specimens were stored at 37 °C for 48 h, and then sectioned at 2, 4 and 6 mm from the apex. The percentage of gutta-percha, sealer and void areas were evaluated using a stereomicroscope and sealer penetration perimeter by confocal laser microscope. Statistical analyses were performed using the Kruskall-Wallis and Dunn tests (p<0.05). The mechanical method required a shorter time for the lateral compaction than the manual method (p<0.05). There were no significant differences (p>0.05) for the perimeter of the dentin with sealer penetration among all groups. The mechanical method showed a higher (p<0.05) percentage of gutta-percha and less sealer at the 4 mm section in comparison with the manual method. The ultrasonic group showed intermediate values. The void areas found in the root filling were similar (p>0.05) between the three methods. In conclusion, the fastest lateral compaction was achieved with the mechanical method, and all the methods showed void areas in the root filling.

Comparison of two techniques for selection of master gutta-percha cone using micro-computed tomography

This study used micro-computed tomography (micro-CT) to evaluate the fit of the master gutta-percha cone at time of cone fit, gutta-percha volume in the filling material, and the filling material volume in relation to the canal at the apical limit of the working length. Root canals of 20 maxillary central incisors were prepared with rotary instruments and distributed into two groups (n=10). The gutta-percha cone tip was either plasticized (apical thermal impression technique - ATI) or not (conventional technique - CT), and its apical fit was checked. The apical 1 mm of working length was examined with a micro-CT, canals were filled with gutta-percha and sealer, and new micro-CT scans were obtained. In CT, gutta-percha filled 35.83 ± 15.05% of the canal at cone selection and 38.72 ± 11.64% after filling. In ATI, these values were 23.14 ± 7.74% and 26.98 ± 20.40%, respectively. Gutta-percha volume in the filling material, and filling material volume in relation to the canal were, respectively, 61.28 ± 11.64% and 87.76 ± 9.98% for CT, and 73.00 ± 20.41% and 89.96 ± 9.08% for ATI. No significant difference was found between cone selection and after canal filling, for either CT (p=0.593) or ATI (p=0.4975). The techniques did not differ significantly with respect to gutta-percha volume in the filling material (p=0.132) and filling material volume in relation to the canal (p=0.612). An ideal fit of the master gutta-percha cone at working length was not achieved regardless of the cone selection technique, and the material-filled area was similar for both techniques.

Influence of Endodontic Sealer Composition and Time of Fiber Post Cementation on Sealer Adhesiveness to Bovine Root Dentin

This study aimed to assess the influence of the type of endodontic sealer (salicylate resin-based sealer vs. two endodontic sealers) and the time of fiber post cementation after root filling on the post adhesion to bovine root dentin. Sixty bovine roots were assigned to six groups (n=10), considering an experimental design with two factors (factorial 3x2): endodontic sealer factor in three levels [epoxy resin-based sealer (AH Plus), eugenol-based sealer (Endofill), and salicylate resin-based sealer plus mineral trioxide aggregate - MTA (MTA Fillapex)] and time for post cementation factor in two levels (immediate post cementation or 15 days after root canal filling). After post cementation, 2-mm-thick slices were produced and submitted to push-out test. The failure modes were analyzed under a 40× stereomicroscope and scored as: adhesive at cement/dentin interface; adhesive at cement/post interface; cement cohesive; post cohesive; dentin cohesive; or mixed. Data were analyzed using two-way ANOVA and Tukey's post-hoc tests (α=0.05). When the fiber posts were cemented immediately after the root canal filling, the bond strengths were similar, independent of the endodontic sealer type. However, after 15 days, the epoxy resin-based sealer presented higher bond strength than the other sealers (p<0.05). Comparison between each sealer in different experimental times did not reveal any differences. The main failure type was adhesive at dentin/cement interface (89.4%). The time elapsed between the root canal filling and post cementation has no influence on post/root dentin adhesion. On the contrary, the type of endodontic sealer can influence the adhesion between fiber posts and root dentin.

Adhesion of real seal to human root dentin treated with different solutions

The aim of this study was to evaluate the effects of different irrigants on sealer-dentin bond strength when using Real Seal. Thirty single-rooted teeth were divided into 3 groups. In one group, the teeth were irrigated with 3 mL of 2.5% NaOCl after each file change, flushed with 17% EDTA for 3 min and finally rinsed with 3 mL of 2.5% NaOCl. In the other two groups, rinse with NaOCl was replaced with 2% chlorhexidine gluconate (CHX) and 0.9% saline, respectively. Each root was sectioned transversally into apical, middle and coronal thirds to obtain 2-mm-thick slices. Each slice was filled with Real Seal and Resilon. Push-out test was used to analyze bond strength and failure modes were classified as adhesive, cohesive or mixed, according to SEM observations. The push-out test did not reveal any statistically significant difference (p>0.05) between the irrigants. However, the groups exhibited significantly different (p<0.05) bond strengths in terms of the root canal third. Higher bond strength was observed at the apical third when compared with coronal third, while middle third presented intermediary values. Fifteen specimens were analyzed by SEM (5 per group). Eleven specimens exhibited adhesive failures (5 in saline, 4 in NaOCl and 2 in CHX group); 2 cohesive failures were observed in the CHX group, and 1 mixed failure each was observed in the CHX and NaOCl groups. The tested irrigants did not influence the bond strength of Resilon and Real Seal to dentin. The apical third exhibited higher mean bond strengths and adhesive failures were predominant.