Root Reinforcement after Obturation with Calcium Silicate-based Sealer and Modified Gutta-percha Cone

REINFORCING EFFECT OF INTRARADICULAR FILLING MATERIALS IN SIMULATED IMMATURE MANDIBULAR PREMOLARS WITH MINERAL TRIOXIDE AGGREGATE APICAL BARRIER: A WEIBULL ANALYSIS

INTRODUCTION

Incomplete root formation following pulp necrosis requires mineral trioxide aggregate (MTA) apexification. Although effective, this treatment does not increase the root thickness, necessitating additional reinforcement. This study aimed to evaluate the fracture resistance of simulated immature mandibular premolars apexified with MTA and reinforced with various materials using Weibull analysis.

METHODS

Ninety human mandibular first premolars were prepared to simulate immature teeth. After MTA apexification, teeth were divided into six groups: negative control (intact teeth), positive control (untreated apexified teeth), gutta-percha (GP) with AH Plus, GP with Bioceramic sealer, core, and fiber post/core. The teeth underwent thermocycling, eriodontal ligament simulation, and fracture testing.

RESULTS

Negative and positive controls exhibited the highest and lowest fracture resistance, respectively. Core and fiber post/core had hazard ratios of 4.79 and 6.23, respectively, outperforming GP with AH Plus and GP with Bioceramic sealer (hazard ratios: 14.23 and 17.22, respectively). Most fractures occurred in the coronal third.

CONCLUSIONS

Intraradicular reinforcement materials (fiber post/core and core) provided greater support to MTA-apexified roots than conventional root filling materials (GP/AH Plus and GP/Bioceramic sealer).

Comparative Analysis of Fracture Resistance of Endodontic Sealer Types and Filling Methods

With the advent of bioceramic sealers, sealers have become a more important filling material for endodontic treatment. When a solid sealer, rather than an elastic gutta-percha, occupies a significant portion of the root canal, it is unclear whether the tooth structure will be strengthened to withstand stress or whether the increased stiffness will transmit the load directly to the entire root, potentially causing root fracture. This study compared the fracture resistance and fracture patterns of roots filled with various root canal sealers, including bioceramic sealers, and each corresponding filling technique. Five groups (n = 10) were tested, including no endodontic treatment, no canal obturation, resin-based sealers with continuous-wave compaction, bioceramic sealers with single-cone technique, and mineral trioxide aggregate (MTA) orthograde obturation. The specimens were radiographed to assess the filling quality. After embedding the specimens in acrylic resin, fracture resistance was tested by a universal testing machine, and fracture features were examined microscopically. The results showed that the bioceramic sealer group using the single-cone technique had the highest fracture strength. Radiographic analysis revealed that achieving void-free filling was more difficult with MTA orthograde obturation compared to resin-based and bioceramic sealer groups. No significant variation in fracture features was observed across the groups.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The impact of the filling technique with two sealers in bulk or associated with gutta-percha on the fatigue behavior and failure patterns of endodontically treated teeth

Background

The present in vitro study aimed to evaluate the fatigue behavior of teeth filled with a calcium silicate-based sealer (Bio-C Sealer, BC) or an epoxy resin-based sealer (AH Plus, AH), in bulk or associated with gutta-percha as main core material.

Methods

Seventy-two sound human maxillary anterior teeth were initially selected. Sixty of them, were randomly chosen, and had their root canals prepared using nickel-titanium reciprocating instruments, being again randomly assigned to five experimental groups (n = 12): C+ (control + prepared but not filled); BC-B (BC in bulk); BC-GP (BC+ gutta-percha); AP-B (AH in bulk); AP-GP (AH+ gutta-percha). An additional negative control group (C-) was considered (n = 12), consisting only on sound teeth, without preparation and filling. The specimens were submitted to a survival analysis after the cyclic fatigue test.

Results

Sound teeth (C-) presented the best fatigue performance (P < 0.05), being similar only to the AP-GP group (P > 0.05). Despite that, all experimental groups showed similar fatigue behavior (P > 0.05) to C+ (BC-B = BC-GP = AP-B = AP-GP = C+). Based on that, it can be seen that the use of gutta-percha, as a main core material, associated with the AH Plus sealer, reestablished the mechanical fatigue performance of endodontically treated teeth comparable to sound teeth, still consisting on the most promising approach to rehabilitate such scenario. Teeth filled in bulk, had discreetly higher risk of premature failures and inferior fatigue performance.

Fiber post cemented using different adhesive strategies to root canal dentin obturated with calcium silicate-based sealer

BACKGROUND

Calcium silicate-based sealer has favorable properties for root canal filling, including hydroxyapatite formation during the setting process. However, this process can cause difficulty during post space preparation when the sealer is set. Additionally, the remaining sealer could interfere with the bond strength of fiber post to root canal dentin. The different adhesive strategies and fiber post cementation time may affect the bond strength of the fiber post. Thus, the objective of this study was to evaluate the effect of etching modes of Scotchbond™ Universal Plus adhesive and post cementation time on the push-out bond strength of a fiber post cemented in root canals obturated with calcium silicate-based sealer.

METHODS

Fifty-four teeth were randomly allocated to 6 groups (n = 9) based on etching modes: self-etch (SE) or etch-and-rinse (ER); post space preparation and cementation time: immediate (Im) or 7-day delayed (De): Im-Im, Im-De, and De-De. The root canals were obturated with calcium silicate-based sealer and the post space preparation was performed. The fiber post was cemented using RelyX™ Universal resin cement according to each group's design. For the push-out bond strength test, 1-mm slices of the coronal, middle, and apical regions were tested using a universal testing machine. The failure mode analysis was determined using a stereomicroscope. The data was analyzed with three-way analysis of variance.

RESULTS

No negative effects of etching modes, post space preparation or cementation time on push-out bond strength were detected (p > 0.05). Additionally, the root canal region also did not significantly affect the bond strength (p > 0.05).

CONCLUSION

No significant differences were observed between the etching modes, post space preparation and cementation time and among root canal regions.

CLINICAL RELEVANCE

The different etching modes of adhesive and post cementation time did not affect the bond strength of fiber post in calcium silicate filled-root canal.

In vitro evaluation of the impact of a bioceramic root canal sealer on the mechanical properties of tooth roots

Bacground/purpose

Endodontically treated teeth are more prone to vertical root fracture with the mechanical property changes to some extent during root canal treatment. This study aimed to investigate the effects of a bioceramic sealer on the mechanical properties of tooth roots.

Materials and methods

Dentin discs were dried by two different methods (ethanol drying and paper points drying) and then filled with a BC sealer named iRoot SP. SEM and EDS were used to analyze the newly formed minerals in dentin tubules. Elastic modulus and hardness of the secondary dentin in areas proximal to the primary dentin (PD-SD) and areas proximal to canal or iRoot SP (SD-C/SD-iRoot SP) were measured using nanoindentation technique. The compressive strength of roots filled with iRoot SP were tested by compressive loading test.

Results

(1) Penetration and mineralization: Paper points drying was more conducive to iRoot SP adhesion, spreading and penetration into the dentin tubules than 95% ethanol drying. (2) Micromechanical properties: After filling root canal with iRoot SP, the elastic modulus and hardness of SD-iRoot SP were higher than those of PD-SD (P = 0.001 and P = 0.000). (3) Fracture resistance: The compressive strength of the roots filled with iRoot SP was not significantly different from that of the roots unprepared and unfilled (P = 0.957), but was higher than that of the roots prepared and unfilled (P = 0.009).

Conclusion

Excessive drying (95% ethanol drying method) is not conducive to the penetration and mineralization of the BC sealer iRoot SP into dentin tubules. The good bioactivity of iRoot SP was responsible for increasing the elastic modulus and hardness of dentin, which strengthened the prepared roots.

Application of Nanomaterials in Endodontics

Recent advancements in nanotechnology have introduced a myriad of potential applications in dentistry, with nanomaterials playing an increasing role in endodontics. These nanomaterials exhibit distinctive mechanical and chemical properties, rendering them suitable for various dental applications in endodontics, including obturating materials, sealers, retro-filling agents, and root-repair materials. Certain nanomaterials demonstrate versatile functionalities in endodontics, such as antimicrobial properties that bolster the eradication of bacteria within root canals during endodontic procedures. Moreover, they offer promise in drug delivery, facilitating targeted and controlled release of therapeutic agents to enhance tissue regeneration and repair, which can be used for endodontic tissue repair or regeneration. This review outlines the diverse applications of nanomaterials in endodontics, encompassing endodontic medicaments, irrigants, obturating materials, sealers, retro-filling agents, root-repair materials, as well as pulpal repair and regeneration. The integration of nanomaterials into endodontics stands poised to revolutionize treatment methodologies, presenting substantial potential advancements in the field. Our review aims to provide guidance for the effective translation of nanotechnologies into endodontic practice, serving as an invaluable resource for researchers, clinicians, and professionals in the fields of materials science and dentistry.

Evaluation of stress distributions of calcium silicate-based root canal sealer in bulk or with main core material: A finite element analysis study

This research aimed to assess the stress distribution in lower premolars that were obturated with BioRoot RCS or AH Plus, with or without gutta percha (GP), and subjected to vertical and oblique forces. One 3D geometric model of a mandibular second premolar was created using SolidWorks software. Eight different scenarios representing different root canal filling techniques, single cone technique with GP and bulk technique with sealer only with occlusal load directions were simulated as follows: Model 1 (BioRoot RCS sealer and GP under vertical load [VL]), Model 2 (BioRoot RCS sealer and GP under oblique load [OL]), Model 3 (AH Plus sealer with GP under VL), Model 4 (AH Plus sealer with GP under OL), Model 5 (BioRoot RCS sealer in bulk under VL), Model 6 (BioRoot RCS in bulk under OL), Model 7 (AH Plus sealer in bulk under VL), and Model 8 (AH Plus sealer in bulk under OL). A static load of 200 N was applied at three occlusal contact points, with a 45° angle from lingual to buccal. The von Mises stresses in root dentin were higher in cases where AH Plus was used compared to BioRoot RCS. Furthermore, shifting the load to an oblique direction resulted in increased stress levels. Replacing GP with sealer material had no effect on the dentin maximum von Mises stress in BioRoot RCS cases. Presence of a core material resulted in lower stress in dentin for AH Plus cases, however, it did not affect the stress levels in dentin for cases filled with BioRoot RCS. Stress distribution in the dentin under oblique direction was higher regardless of sealer or technique used.

Post retention strength of apical and conventional coating obturation methods using bioceramic sealer: a laboratory investigation

BACKGROUND

Once bioceramic sealer (BCS) enters the dentinal tubules, it cannot be reliably removed. BCS-occupied dentinal tubules reduce fibre post retention strength. Coating gutta-percha with BCS only on the apical portion may improve post retention strength due to increased retention strength between the dentin and resin cement interface. The aim of the study was to test this hypothesis.

METHODS

Root canals of 27 extracted human mandibular premolars were instrumented and randomly assigned to three obturation methods: conventional coating (CC), non-coating (NC), and apical coating (AC). The root canals were obturated with gutta-percha to 4 mm from the working length under an operating microscope. After the BCS was completely set, post spaces were prepared, and quartz fibre posts were cemented. The apical 4.5 mm of the roots were removed. Two samples were prepared at the apical, middle, and coronal root levels (one for scanning electron microscope (SEM) study and another for the push out bond strength (PBS) test). After the PBS test, the samples were examined with a stereo microscope to determine the failure mode: dentine-cement (DC), post-cement (PC) and mixed. The PBS data were analysed by One way ANOVA for the specific obturation method effects. Repeated ANOVA was used for the specific effects of the root levels on PBS in different obturation methods.

RESULTS

At all three root levels, more continuous hybrid layers and denser resin tags were found in the NC and AC than the CC group. The AC and NC groups' PBS was significantly higher than the CC group at the apical 1/3 (p = 0.002 and p = 0.001) and coronal 1/3 (p = 0.016 and p = 0.041). The PBS in the CC group at the middle 1/3 was significantly higher than the apical 1/3 (p = 0.022). DC failure mode was most commonly found in the CC group, while PC failure mode was found most frequently in the NC and AC groups.

CONCLUSIONS

The apical coating obturation method significantly increased PBS over the conventional coating method, potentially reducing fiber post dislodgement. However, this study was only preliminary. Clinical studies are required to confirm the results.

2D and 3D Erosion Landscape Analysis of Endodontic-Treated Teeth Using EDTA and HEDP as Chelating Agents: A High-Resolution Micro-Computed Tomographic Study

This study aimed to assess the amount of erosion during activated endodontic irrigation with either HEDP or EDTA via high-resolution micro-computed tomography. Two root canals of twenty premolars were prepared with ProTaper Next and irrigated with sodium hypochlorite. Palatal canals, which served as control groups, were sealed, while buccal canals were further irrigated with either EDTA (n = 10) or HEDP (n = 10), which served as test groups. Micro-CT was performed to measure erosion depth. For 2D and 3D measurements, non-parametric repeated ANOVA measurements and post hoc tests were performed. 2D analysis showed highly significant differences between the case groups at each position of the root (p ≤ 0.01). The cervical and apical positions showed significant differences in the EDTA group (p = 0.03). The 3D analysis also showed significant differences between both chelating agents (p < 0.01) and the case and control groups (p = 0.01). The mean erosion depths in the cervical, middle, and apical thirds of the EDTA group were 45.75, 41.79, and 32.25 µm, and for the HEDP group were 20.25, 16.40, and 15.96 µm, respectively. HEDP seems to have a significantly less erosive effect. Different irrigation protocols with harsher conditions, as might be the case during endodontic retreatment, could be assessed with micro-CT.

Influence of bioceramic cones on the quality of root canal filling relative to bond strength and adaptation of the adhesive interface

AIM

To evaluate the bond strength (BS) and analysis of the adhesive interface in root canals filled with bioceramic gutta percha sealers and cones.

MATERIAL AND METHODS

Ninety-six maxillary canines were divided into eight groups according to the endodontic sealer (AH Plus, AH Plus Bioceramic, Bio-C Sealer or Bio-C Sealer Ion+ and gutta percha cones (conventional or bioceramic) tested. They were analyzed using the BS test, failure pattern, analysis of the adhesive interface by scanning electron microscopy and confocal laser scanning microscopy. The BS data were compared between groups using the analysis of variance test with the Turkey post-test. The chi-square test was used to assess the type of failure and the non-parametric Mann-Whitney and Kruse-Wallis tests (P < 0.05).

RESULTS

Analysis of variance showed higher BS values for the groups of bioceramic gutta percha cones in Bio-C Sealer Ion+ (8.38 ± 4.27), AH Plus Bioceramic (6.19 ± 3.28), Bio-C Sealer (5.70 ± 3.18), AH Plus (4.61 ± 2.11) and for conventional gutta percha cones in AH Plus sealers (4.26 ± 2.35), Bio-C Sealer Ion + (3.63 ± 2.29), Bio-C Sealer (2.94 ± 2.32) and AH Plus Bioceramic (1.19 ± 0.89) (P < 0.05). Relative to the type of failure and adaptation of the types of filling material, a higher percentage of mixed failures was observed (gaps between 1 µm-10 µm) for the group with bioceramic gutta percha cones (P < 0.001).

CONCLUSION

The bond between sealers and bioceramic gutta percha cones showed higher bond strength values and greater penetration into the dentin tubules.

CLINICAL RELEVANCE

The filling the root canal system with bioceramic sealers should be associated with bioceramic gutta percha cones.

The effect of sealer type and obturation technique on the fracture resistance of endodontically treated roots

OBJECTIVE

This study evaluated the effect of sealer type with various obturation techniques on the fracture resistance of root filled teeth.

MATERIALS AND METHODS

Eighty mandibular premolars were collected, and root canals of 70 of them were prepared by Mtwo system up to 40/04. Thirty teeth were obturated using TotalFill BC sealer, and 30 using AH Plus sealer, with one of the obturation techniques (N = 10), namely cold lateral compaction (CLC), warm vertical compaction (WVC), and single cone (SC). Ten teeth were left without obturation as a positive control, and the other 10 teeth were not prepared serving as a negative control. Teeth were stored for 3 weeks, and the crowns were separated and the roots were subjected to fracture test using a universal testing machine.

RESULTS

Data was analyzed by ANOVA followed by Tukey's test. Fracture resistance of the TotalFill groups was significantly higher than the AH Plus groups in each obturation technique, and SC had the highest fracture resistance regardless of sealer used (P < 0.05). Obturation of the root canal by TotaFill BC sealer increased the calcium/phosphorous ratio in the dentin of the root.

CONCLUSIONS

Obturation with TotalFill BC sealer improved the fracture resistance of the roots more than AH Plus sealer, and obturation with SC resulted in higher fracture resistance than CLC and WVC.

CLINICAL RELEVANCE

Obturation of the root canal with Bioceramic sealer with single cone obturation technique could reduce the incidence of vertical root fracture.

Effect of Different Root Canal Drying Protocols on the Bond Strength of Two Bioceramic Sealers

OBJECTIVES

 This study evaluated in vitro the effect of two different drying protocols on the dentin bond strength of two different bioceramic sealers (Sealer Plus BC [SP] and Bio C Sealer [BCS]). Bond strength and failure mode were evaluated according to the sealer, drying protocol, and root canal third.

MATERIALS AND METHODS

 Sixty extracted human mandibular single-rooted premolars were selected after anatomical standardization. The crowns were sectioned and root canals were prepared. Roots were randomly divided into four groups (n = 15 each). Each group was assigned a combination of one of the evaluated sealers (SP or BCS) and one of the drying protocols: canals dried with paper points (PP) or irrigation with saline followed by aspiration with silicon cannulas (IA). Obturations were performed using a single-cone technique. The teeth were temporized and stored for 7 days (100% humidity, 37°C). Roots were cut to obtain 2 mm thick discs for each third (coronal, middle, and apical). Push-out tests were performed on a universal testing machine, and the bond strength (MPa) of each specimen was calculated by dividing the load (N) by the interface area. Failure type was assessed under ×4 magnification.

STATISTICAL ANALYSIS

 Data were statistically analyzed with a significance set at 5%. An analysis of variance test followed by the Games-Howell post-hoc test was used to compare the mean values between the groups and the interaction of the variables.

RESULTS

 The predominant failure type was cohesive, followed by mixed failure and adhesive in all groups. The apical third presented the highest bond strength (p < 0.05) regardless of the group, followed by the middle and coronal thirds. Overall, the SP PP group had the highest mean bond strength (p < 0.01), but the SP sealer was negatively affected by the IA drying protocol in the coronal and middle thirds. The BCS presented similar results within the third stage, regardless of the drying protocol.

CONCLUSIONS

 Sealer Plus BC had a higher bond strength than Bio C Sealer, but it was negatively affected by the irrigation-aspiration protocol in the coronal and middle thirds. For the apical third, there was no difference between the groups; thus, a similar bond strength was observed regardless of the drying protocol or sealer.

Influence of long -term thermal cycling and masticatory loading simulation on bond strength of roots filled with epoxy resin and calcium silicate based sealers

BACKGROUND

The aim of this study was to evaluate the effect of thermal and mechanical cyclic aging using a mastication simulator on push-out bond strength of mandibular premolars obturated with AH Plus and BioRoot RCS root canal sealers.

METHODS

With REVO-S files up to SU/0.06 taper, 48 single-rooted premolar teeth were instrumented. The teeth were randomly divided into two main groups (n = 24) based on the two root canal sealers used (AH Plus and BioRoot RCS). All teeth were obturated with h matched-taper single-cone. Each main group was then subdivided into three subgroups (A, B, and C) (n = 8). Group A served as the negative control group (no-thermocycling aging). While groups B and C were subjected to thermal changes in a thermocycler machine (15,000 and 30,000 thermal cycles, respectively), followed by two different dynamic loading periods, 3 × 105 and 6 × 105 in a masticatory simulator with a nominal load of 5 kg at 1.2 Hz which represent roughly 1½ and 3 years of clinical function respectively. 2 mm slice at 3 levels, apical, middle, and coronal, to obtain 3 sections were prepared and subjected to push-out test using a universal testing machine. Statistical analysis was performed using analysis of variance (ANOVA) followed by a Tukey post hoc comparisons test and an independent T-test. A significance level of 5% was used.

RESULTS

After thermal-mechanical cyclic aging, the two root canal sealers showed a significantly decreased in push-out bond strength (p < 0.05), however, AH Plus had significantly higher bond strength values than BioRoot RCS after cycling aging.

CONCLUSIONS

It could be concluded that thermal-mechanical cyclic aging had a significant impact on the outcome of the dislodgment resistance of AH Plus and BioRoot RCS.

Gap volume and sealer penetration of C-shaped root canals obturated with cold hydraulic technique and calcium silicate sealer

This study compared the gap volume and sealer penetration in C-shaped root canals prepared with adaptive core rotary files and obturated with cold hydraulic compaction using calcium-silicate sealer, warm vertical hybrid compaction, or lateral compaction using epoxy-resin sealer. Thirty-six extracted mandibular molars with pulpal floor configuration Types I and III were used. The teeth were prepared using XP-Shaper and XP-Finisher and obturated with: group 1: cold hydraulic compaction/calcium silicate, group 2: warm vertical hybrid compaction/epoxy resin, or group 3: lateral compaction/epoxy resin. The gap volume was evaluated using μ-CT. The sealer penetration depth and area were evaluated using confocal laser scanning microscopy. The gap volume in groups 1, 2, and 3 was 0.82%, 0.24%, 0.80%, respectively, which were not significantly different (p > 0.05). The gap volumes in the obturated C-shaped canals were not significantly different among the CHC/CSBS, WHC/ERS, or LC/ERS groups. CHC/CSBS was the most convenient technique.

Functionalization of gutta-percha surfaces with argon and oxygen plasma treatments to enhance adhesiveness

Gutta-percha's lack of adhesion has been presented as a drawback to avoid gaps at sealer/gutta-percha interface. Plasma treatments have been scarcely assessed on gutta-percha surfaces as a method of enhancing adhesiveness. This study aimed to evaluate the effect of low-pressure Argon and Oxygen plasma atmospheres on conventional and bioceramic gutta-percha standardized smooth discs, assessing their roughness, surface free energy, chemical structure, and sealer wettability. A Low-Pressure Plasma Cleaner by Diener Electronic (Zepto Model) was used. Different gases (Argon or Oxygen), powers (25 W, or 50 W), and exposure times (30 s, 60 s, 120 s, or 180 s) were tested in control and experimental groups. Kruskal-Wallis and Student's t-test were used in data analysis. Statistically significant differences were detected when P < 0.05. Both gases showed different behaviors according to the parameters selected. Even though chemical changes were detected, the basic molecular structure was maintained. Argon or Oxygen plasma treatments favoured the wetting of conventional and bioceramic gutta-perchas by Endoresin and AH Plus Bioceramic sealers (P < 0.001). Overall, the functionalization of gutta-percha surfaces with Argon or Oxygen plasma treatments can increase roughness, surface free energy and wettability, which might improve its adhesive properties when compared to non-treated gutta-percha.

Effect of a bioactive glass-based root canal sealer on root fracture resistance ability

Background/purpose

The root fracture resistance of endodontically treated teeth is decreased significantly, and it is more likely to fracture. This study aimed to evaluate the effect of a novel root canal sealer based on bioactive glass (BG) on root fracture resistance and explore its mechanism.

Materials and methods

The BG-based root canal sealer (BG Sealer) was prepared by mixing a kind of bioactive glass (10.8% P₂O₅, 54.2% SiO₂, 35% CaO, mol.%, named PSC), zirconia (ZrO₂) powder, sodium alginate (SA) and phosphate solution (PS). A pH meter was used to measure the pH of simulated body fluid (SBF) after immersion with BG Sealer at different time. After preparing the samples of BG sealer with a diameter of 4 mm and a height of 6 mm, the compressive strength was tested by a universal testing machine. The scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to detect and analyze the mineral status of root canal systems filled with BG Sealer. The push out test was used to measure the push out bond strength of BG Sealer. The fracture resistance of root canals filled with BG Sealer was detected by the compressive loading test. Bioceramic root canal sealer iRoot SP was set as the control group.

Results

(1) Physicochemical properties: The pH value of SBF immersed with BG Sealer increased slightly up to 7.68, while the pH of SBF immersed with iRoot SP increased to 12.08. The compressive strength of the novel BG Sealer was 4.62 ± 1.70 MPa, which was lower than that of iRoot SP (P < 0.05). (2) Mineralization: The hydroxyapatite layers were observed on the surface of BG Sealer and iRoot SP after being immersed in SBF for 4 weeks. BG Sealer and iRoot SP were both able to penetrate into the dentin tubules, duplicate the morphology of root canals well, and form a layer of hydroxyapatite. (3) Adhesion to dentin: There was no significant difference between the push out bond strength of the novel BG Sealer and iRoot SP (P > 0.05). (4) Fracture resistance: After immersion in SBF for 4 weeks, the fracture resistance of roots filled with BG Sealer and iRoot SP was 454.16 ± 155.39 N and 445.50 ± 164.73 N, respectively, both of which were not statistically different from that of the roots unprepared and unfilled (394.07 ± 62.12 N) (P > 0.05), whereas higher than that of the roots prepared and unfilled (235.36 ± 83.80 N) (P < 0.05).

Conclusion

The novel BG Sealer has good adhesion to the root dentin, can penetrate into the dentin tubules to generate minerals, and meanwhile can improve the fracture resistance of the roots after root canal treatment. It is expected to be a bioactive root canal sealer with good clinical application prospects.

The Effect of Primary Root Canal Treatment on Dentinal Tubule Penetration of Calcium Silicate-based Sealers during Endodontic Retreatment

INTRODUCTION

The aim of this study was to evaluate the effect of previous root canal treatment on dentinal tubule penetration of calcium silicate-based sealers during endodontic retreatment and to compare 2 different (commonly used and modified) tubule penetration depth measurement techniques.

METHODS

The crowns of mandibular premolar teeth were removed, and root canals were prepared (ProTaper Universal; Dentsply Sirona, York, PA) and obturated using AH Plus (AH; Dentsply DeTrey, Konstanz, Germany), MTA Fillapex (MTAF; Angelus, Londrina, Brazil), and WellRoot ST (WRST; Vericom, Gyeonggi-do, South Korea); 0.1% red Rhod-2 dye (Chemodex, St Gallen, Switzerland) was added to the sealers. After storage for 3 weeks (37°C, 100% humid), the following sealer combination subgroups were created (the sealer used during the primary root canal treatment/the sealer used during the retreatment, n = 8): AH/AH, AH/MTAF, and AH/WRST; MTAF/AH, MTAF/MTAF, and MTAF/WRST; and WRST/AH, WRST/MTAF, and WRST/WRST. Green Fluo-3 dye (0.1%) was added to the sealers during retreatment. Sealer penetration depths were measured at 8 points and averaged, and the ratio of the retreatment sealer to the initial sealer was recorded as the mean tubule penetration depth ratio in the first technique, whereas the percentage of the circumferential penetration area ratios of the retreatment and initial sealers was calculated in the second technique. Statistical analyses were performed using Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests.

RESULTS

The mean penetration depth of AH and MTFA was found to be higher at the coronal third region in the control groups (P < .05). Both methods showed a significant difference among the groups at the coronal and median regions (P < .05). The AH/WRST, MTAH/AH, MTAF/MTAF, MTAF/WRSTS, and WRST/WRST groups showed deeper tubule penetration (first technique, P = .01). Both techniques showed that the penetration depth of the sealers was the same at the apical region (P > .05), whereas a difference was found among the techniques at the coronal and median regions. The sealers used in the previous root canal treatment limited the penetration depth of the sealers used during the retreatment process (P < .05). When MTAF was used as the initial sealer, the penetration depth of the second sealer did not change, whereas if WRST was the initial sealer, the penetration depth of the sealers at the median and apical regions is negatively affected during the retreatment process (P < .05).

CONCLUSIONS

Previous root canal treatment affects the penetration depth of calcium silicate-based sealers. The use of AH Plus and MTA Fillapex during the retreatment process showed an advantage. Both measurement techniques showed similar performances at the apical region, whereas the results varied at the coronal and midcoronal regions; therefore, a more stable sealer penetration measurement technique is still necessary.

Clinical and Radiographic Outcome of Non-Surgical Endodontic Treatment Using Calcium Silicate-Based Versus Resin-Based Sealers-A Systematic Review and Meta-Analysis of Clinical Studies

The aim of this paper is to systematically analyse the effect of calcium silicate-based sealers in comparison to resin-based sealers on clinical and radiographic outcomes of non-surgical endodontic treatment in permanent teeth. Methods: The study was conducted according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. The literature search was performed using PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, DOAJ and OpenGrey with no language restrictions. Two reviewers critically assessed the studies for eligibility. Grading of Recommendations, Assessment, Development and Evaluations (GRADE) was carried out to assess the evidence. Meta-analysis of the pooled data with subgroups was carried out using the RevMan software (p < 0.05). Results: Results from the included studies showed that there were no significant differences between the groups in the 24 h post-obturation pain levels (mean difference (MD), −0.19, 95% CI = −0.43−0.06, p = 0.14, I2 = 0%), but at 48 h (MD, −0.35, 95% CI = −0.64−0.05, p = 0.02, I2 = 0%), a significant difference was observed in favour of calcium silicate sealers. Furthermore, there were no significant differences between the two sealers due to risk of onset or intensity of postoperative pain, need for analgesic and extrusion of the sealer. The heterogeneity assessed using Q test between the included studies was 97% (I2). Conclusions: Within the limitations of this review, the paper shows that calcium silicate-based sealers exhibited optimal performance with similar results to resin-based sealers in terms of average level of post-obturation pain, risk of onset and pain intensity at 24 and 48 h. The observations from the included studies are informative in the clinical evaluation of calcium silicate-based sealers and provide evidence for the conduction of well-designed, controlled randomised clinical trials for a period of at least four years in the future.

Natural Polymer Eucommia Ulmoides Rubber: A Novel Material

As the second natural rubber resource, Eucommia ulmoides rubber (EUR) from Eucommia ulmoides Oliver is mainly composed of trans-1,4-polyisoprene, which is the isomer of natural rubber cis-1,4-polyisoprene from Hevea brasiliensis. In the past few years, the great potential application of EUR has received increasing attention, and there is a growing awareness that the natural polymer EUR could become an emerging research topic in field of the novel materials due to its unique and excellent duality of both rubber and plastic. To gain insight into its further development, in this review, the extraction, structure, physicochemical properties, and modification of EUR are discussed in detail. More emphasis on the potential applications in the fields of the environment, agriculture, engineering, and biomedical engineering is summarized. Finally, some insights into the challenges and perspectives of EUR are also suggested.

Effect of final irrigation protocols on the fracture resistance of roots with varying dentine thickness

This study evaluated the effects of 9% etidronic acid (HEBP) and 17% ethylenediaminetetraacetic acid (EDTA) used either with conventional syringe irrigation (CSI) or passive ultrasonic irrigation (PUI) on the fracture resistance of roots with different dentine thickness. The root canals of 120 extracted teeth were widened, leaving dentinal walls with different thicknesses of either 0.75 mm, 1.50 mm, or 2.25 mm with 40 teeth in each group. Within each of these groups, four subgroups (n = 10) were formed according to the final irrigation regimens applied: 2.5% NaOCl-17% EDTA with CSI; 2.5% NaOCl-17% EDTA with PUI; 2.5% NaOCl + 9% HEBP with CSI; 2.5% NaOCl + 9% HEBP with PUI. The irrigated root canals were obturated with AH Plus sealer and gutta-percha cones. A compressive vertical loading was applied to the samples and the force at fracture was recorded. Data were statistically analysed using a multiple linear regression analysis. The most influencing factor for the fracture strength of roots was the remaining dentine thickness, followed by the irrigation method, and then the irrigation solution. The samples irrigated using PUI were statistically significantly more resistant to fracture than those using CSI (mean difference = 116.3 N; 95% CI = [53.9, 178.6] N). The application of HEBP was associated with higher resistance to fracture than the application of EDTA (mean difference = 71.0 N; 95% CI = [8.6, 133.3] N).

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

Objectives

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

Materials and methods

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

Results

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

Conclusions

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

Clinical relevance

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

Comparing dentinal tubule penetration of conventional and 'HiFlow' bioceramic sealers with resin-based sealer: An in vitro study

This study compared the depth and percentage of dentinal tubule penetration for single-cone (SC) and warm vertical (WV) obturation techniques with two different bioceramic sealers (BC Sealer [BCS], BC Sealer HiFlow [BCSHF]) and an epoxy resin-based sealer (2Seal easymiX). Fifty canals were filled with BCS, BCSHF or resin-based sealer (RBS). Teeth in BCS and BCSHF groups were filled with SC or WV techniques, and teeth in the control group (RBS) filled with WV technique only. The roots were sectioned at 3 mm and 6 mm levels from the apex and evaluated with a confocal laser microscope. There was significantly greater depth and percentage of sealer penetration at the 6 mm section compared to 3 mm (P < 0.05). No statistically significant difference was found in sealer type or obturation technique at the examined levels (P > 0.05). In conclusion, dentinal tubule penetration was similar comparing BC Sealer, BC Sealer HiFlow and RBS using SC and WV techniques.

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

Background/purpose

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

Materials and methods

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

Results

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

Conclusion

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

Assessment of Extrusion and Postoperative Pain of a Bioceramic and Resin-Based Root Canal Sealer

Objectives  The objective of this study was to compare a bioceramic and a resin-based endodontic sealer with regard to extrusion and postoperative pain.

Materials and Methods  Sixty-four patients requiring endodontic treatment of single-rooted maxillary teeth with necrotic pulps were included in this study. The root canal treatments were performed in a single visit using a size 40.06 single-file reciprocating system under 2.5% NaOCl irrigation. After irrigation with 17% ethylenediaminetetraacetic acid (EDTA) and 2.5% NaOCl, the canals were dried and randomly divided into two different groups ( n = 32) depending on the sealer used: resin-based group (RG) in which the canals were filled with the AH Plus, and the bioceramic group (BG) in which the canals were filled with the Sealer Plus BC. Ibuprofen (600 mg) was prescribed every 6 hours if the volunteers experienced pain. The patients registered their pain sensation in a visual analog scale (VAS) card, ranging from 0 to 10 at 24-hour, 48-hour, 72-hour, and 1-week intervals. Statistical analysis  For statistical analysis, the level of significance was set at p < 0.05.

Results  Sealer extrusion occurred in nine patients of the RG and in 19 patients of the BG ( p < 0.05). The average pain level at 24-hour and 48-hour intervals was, respectively, 1.46 ± 1.96 and 0.44 ± 0.86 for RG, and 1.21 ± 2.09 and 0.09 ± 0.38 for BG. There was no report of pain after 48 hours. The mean number of tablets taken for pain relief was 0.03 ± 0.17 for RG and 0.06 ± 0.24 for BG. No statistically significant difference was found with regard to pain level and intake of pain killer tablets ( p > 0.05).

Conclusions  The BG sealer presented significantly more extrusion than the RG sealer. Sealer extrusion was not associated with pain. The average pain level and the mean number of tablets taken for pain relief were similar in both groups.

Shear bond strengths of calcium silicate-based sealer to dentin and calcium silicate-impregnated gutta-percha

AIM

To compare the shear bond strengths of a calcium silicate-based root canal sealer (CSS), to dentin or calcium silicate-impregnated gutta-percha (CSGP), with the shear bond strengths of an epoxy resin-based sealer.

METHODS

For sealer/dentin testing, 40 hemisectioned roots were divided into 2 groups. Coronal root dentin discs were bonded with CSS or epoxy resin-based sealer. For sealer/core material testing, CSGP and conventional gutta-percha discs were bonded with a matching sealer (N = 20 per group). The shear bond strengths were tested using a universal testing machine. The failed modes were analyzed using stereomicroscopy and scanning electron microscopy.

RESULTS

The CSS sealer had significantly higher shear bond strength to dentin than did epoxy resin-based sealer (P < .01). However, shear bond strengths of the 2 sealers to core materials did not significantly differ (P = .74). The remnants of the CSS sealer adhering to dentin or calcium silicate gutta-percha disc were observed.

CONCLUSIONS

The CSS sealer had better adhesion to dentin than did epoxy resin-based sealer. However, the bond of the CSS sealer to impregnated gutta-percha was not superior to the epoxy resin-based sealer bonded to conventional gutta-percha.