Effect of immersion in distilled water or phosphate‐buffered saline on the solubility, volumetric change and presence of voids within new calcium silicate‐based root canal sealers

Bioceramics in Endodontics: Limitations and Future Innovations-A Review

Bioceramic materials for endodontic treatments have gradually transformed over the years into materials with enhanced biocompatibility and chemical and mechanical properties compared to earlier generations. In endodontics procedures, these materials are used as restorative material in applications such as root-end fillings, pulp capping, perforations repair, and apexification repair procedures. However, they have far from ideal mechanical and handling properties, biocompatibility issues, aesthetic concerns due to tooth discolouration, limited antibacterial activity, and affordability, which are amongst several key limitations. Notably, bioceramic materials are popular due to their biocompatibility, sealing ability, and durability, consequently surpassing traditional materials such as gutta-percha and zinc oxide-eugenol sealers. A lack of recent advancements in the field, combined with nanomaterials, has improved the formulations of these materials to overcome these limitations. The existing literature emphasises the benefits of bioceramics while underreporting their poor mechanical properties, handling difficulties, cost, and various other drawbacks. The key gaps identified in the literature are the insufficient coverage of emerging materials, narrow scope, limited insights into future developments, and underreporting of failures and complications of the existing materials. Consequently, this review aims to highlight the key limitations of various endodontic materials, primarily focusing on calcium silicate, calcium phosphate, and bioactive glass-based materials, which are the most abundantly used materials in dentistry. Based on the literature, bioceramic materials in endodontics have significantly improved over recent years, with different combinations of materials and technology compared to earlier generations while preserving many of their original properties, with some having affordable costs. This review also identified key innovations that could shape the future of endodontic materials, highlighting the ongoing evolution and advancements in endodontic treatments.

Evaluation of volumetric and surface stability of calcium silicate-based repair cements at different pHs

OBJECTIVES

The objective of this research was to evaluate the volumetric and surface stability in vitro, to different pH levels, of calcium silicate-based repair cements ready-to-use and powder/liquid exposed.

MATERIALS AND METHODS

Sixty human teeth were retro-prepared to a depth of 3 mm and divided into two groups. The first group included powder/liquid cements Biodentine (Septodont, France) and MTA HP (Angelus, Brazil); the second group included ready-to-use cements Bio-C Repair (Angelus, Brazil) and ENDOCEM MTA (Maruchi, Republic of Korea). All samples were submerged in PBS solution with pH levels of 5, 7, and 12. Initially, the materials were evaluated for porosity, marginal adaptation, and volumetric change using micro-CT, and then re-evaluated after 7 and 30 days of exposure to PBS solution. The samples were characterized using SEM/EDS and RAMAN spectroscopy. Statistical evaluation was performed using ANOVA with a 5% significance level.

RESULTS

Bio-C Repair showed significant statistical differences (p < 0.05) at different pHs in 7 and 30 days compared to other materials, being greater in acidic medium. ENDOCEM, regardless of pH, at 30 days showed fewer voids when compared to other repair cements.

CONCLUSION

This micro-CT study demonstrated that regardless pH, the clinic presentation of calcium silicate-based materials ready-to-use showed higher and loss volumetric than powder/liquid materials at 30 days.

CLINICAL RELEVANCE

Under neutral pH conditions, calcium silicate-based materials are expected to maintain properties such as bioactivity and low solubility. However, in clinical situations involving infection and inflammation, pH variations can impact the physicochemical properties of these materials regardless of their clinical presentation.

In vivo method to evaluate volumetric changes in bioceramic repair materials

This study aimed to evaluate the effect of in vitro immersion solutions or an in vivo method on volumetric change of bioceramic root repair materials: Bio-C Repair (BCR, Angelus, Londrina, PR, Brazil) and Biodentine (BIO, Septodont, Saint-Maur-des-Fossés, France) compared to IRM (Dentsply Sirona, York, Pennsylvania, USA) by using microcomputed tomography (µCT) assessment. Tubes of polyvinyl chloride (PVC, 4 mm of length x 1.3 mm of inside diameter, n = 7) were filled with the materials for volumetric analysis in µCT. Samples were scanned after materials setting and after immersion in distilled water, PBS, or in vivo tissue fluid of subcutaneous tissue of rats for 7 days. IRM showed higher volumetric change than BCR and BIO in all immersion solutions (P<0.05). BIO and BCR presented similar volumetric changes when immersed in PBS and distilled water (P>0.05). When the in vivo method was used, BIO and BCR showed lower volumetric change (P<0.05), including an increase in volume for BCR. The immersion solutions influenced the evaluation of the volumetric change of bioceramic repair materials. Bioceramic materials show greater volumetric stability when evaluated by the in vivo method. The in vivo method in the subcutaneous tissue of rats can be an alternative for analyzing the properties of bioceramic cement, showing similarity with the clinical application.

Clinical outcome of non-surgical root canal treatment using different sealers and techniques of obturation in 237 patients: A retrospective study

OBJECTIVES

The aim of this retrospective study was to compare the clinical results of two root canal sealers and three obturation techniques used for non-surgical root canal treatment.

MATERIALS AND METHODS

A total of two hundred eighty-three root canal treated teeth in two hundred thirty-seven patients with minimum a 6-month follow-up was included for this study. The canals were filled with three different modes: 1) cold lateral condensation (CLC) and AH Plus Sealer; 2) continuous wave condensation technique (CWC) and AH Plus Sealer, and 3) sealer-based obturation technique (SBO) and AH Plus Bioceramic Sealer. The treatment outcome was analysed based on clinical signs and symptoms, and periapical radiograph (periapical index, PAI).

RESULTS

There were no significant differences in treatment outcome between various sealers and filling techniques applied. The sealer extrusion was found most frequently in the CWC group (60.67%), followed by SBO (59.21%) and CLC (21.19%) with statistically significant differences (p < .05). The initial diagnosis, previous treatment and sealer extrusion (p < .05) were prognostic factors that affected treatment outcome.

CONCLUSIONS

Based on the findings of this study, neither the sealer type nor the filling technique affected the treatment success while preoperative diagnosis, previous treatment and sealer extrusion had significant effect on the outcome.

CLINICAL RELEVANCE

A bioceramic sealant applied along with the single-cone technique might be considered as an alternative method in root canal obturation.

Volumetric change of calcium silicate-based repair materials in a simulated inflammatory environment: A micro-computed tomography study

Context

An acidic hydrogen potential (pH) in an inflammatory condition in the periapical tissues may affect the properties of repair bioceramic cement.

Aims

The aim of this study was to evaluate the effect of pH on the volumetric change of the ready-to-use bioceramic NeoPUTTY (NP) compared to the powder/liquid MTA Repair HP (MTAHP) after immersion in butyric acid (BA, pH 4.1) or phosphate-buffered saline (PBS, pH 7.35).

Subjects and Methods

Dentin tubes filled with NP or MTAHP were scanned in micro-computed tomography (micro-CT) after 24 h. Then, the specimens were immersed in 1.5 mL of BA: NP/BA, MTAHP/BA or PBS: NP/PBS, MTAHP/PBS. After 7 days, new micro-CT scans were performed. The percentage of volumetric change (extremities and internal part) of the materials was assessed.

Statistical Analysis Used

ANOVA/Tukey and Kruskal-Wallis tests were performed (α =0.05).

Results

All materials showed a volumetric decrease after immersion in BA or PBS at the extremities in contact with the solutions. MTAHP/BA showed the highest volumetric loss. There was no difference in the volumetric change when the internal part of the materials was evaluated.

Conclusions

An acid pH negatively affects the volumetric stability of MTAHP. Low values of volumetric change were demonstrated for NP in both immersion environments.

A Literature Review of the Effect of Heat on the Physical-Chemical Properties of Calcium Silicate-Based Sealers

INTRODUCTION

Recently, calcium silicate-based sealers (CSSs) have gained popularity in endodontic practice due to their biocompatibility and antimicrobial properties. They are considered viable alternatives to epoxy resin-based sealers. With the increased use of CSSs and warm vertical compaction techniques in root canal treatment, evaluating the impact of heat on CSSs properties is essential, therefore this review aimed to present a qualitative synthesis of available in vitro studies assessing the impact of heat on the physical-chemical properties of CSSs.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis 2020 guidelines, a systematic advanced electronic search was performed in Scopus, Embase, Medline (via PubMed), Web of Science, and Cochrane databases in November 2023 and updated in April 2024. In vitro studies that evaluated the physical-chemical properties of CSSs were eligible. PRILE 2021 guidelines were used for the assessment of the risk of bias-included studies.

RESULTS

The search identified a total of 6421 preliminary results and 10 studies were included for qualitative assessment. Eleven different physiochemical properties were assessed by the included studies. Setting time and flow were the most evaluated property among the studies. A qualitative synthesis of the evidence on each property is presented.

CONCLUSIONS

Based on the in vitro studies assessed in the present systematic review, results reveal that exposing CSSs to heat can accelerate their setting time, reduce their flow, and increase their film thickness. Concerns persist regarding solubility, viscosity, radiopacity, dimensional change, microhardness, porosity, and compressive strength, requiring further research. Certain CSSs, such as MTA Fillapex and Endosequence BC sealer HiFlow, show minimal changes under heat, making them potential candidates for warm filling techniques.

Biocompatibility, bioactivity, porosity, and sealer/dentin interface of bioceramic ready-to-use sealers using a dentin-tube model

This study evaluated the biocompatibility, bioactivity, porosity, and sealer/dentin interface of Sealer Plus BC (SP), Bio-C Sealer (BIOC), TotalFill BC Sealer (TF), and AH Plus (AHP). Dentin tubes filled with the sealers and empty tubes (control group) were implanted in the subcutaneous tissue of rats for different periods (n = 6 per group/period). Number of inflammatory cells (ICs), capsule thickness, von Kossa reaction, interleukin-6 (IL-6) and osteocalcin (OCN) were evaluated. Porosity and voids in the interface dentin/sealers were assessed by micro-computed tomography. The data were submitted to ANOVA/Tukey's tests (α = 0.05). Greater capsule thickness, ICs and IL-6 immunolabeling cells were observed in AHP. No significant difference in thickness of capsule, ICs, and IL-6- immunolabeling cells was detected between SP and TF, in all periods, and after 30 and 60 days between all groups. At 60 days all groups had reduction in capsule thickness, ICs and IL-6 immunolabeling cells. Von Kossa-positive and birefringent structures were observed in the capsules around the sealers. BIOC, SP, and TF exhibited OCN-immunolabeling cells. All sealers had porosity values below 5%, besides low and similar interface voids. BIOC, SP and TF are biocompatible, bioactive, and have low porosity and voids. The dentin-tube model used is an alternative for evaluating bioceramic materials.

Effect of ultrasonic activation on setting time, pH and calcium ion release, solubility, and chemical structure of calcium silicate sealers

This study evaluated the setting time, pH, calcium ion release, solubility, and chemical structure of four calcium silicate sealers after ultrasonic activation (UA). Five sealers were evaluated: Sealer Plus (SP - control); Sealer Plus BC (SPBC), Bio C Sealers (BCS), Endosequence BC Sealer (EBC), and BioRoot RCS (BR). Ten groups were created based on the use or not of ultrasonic activation: SP; SP/UA; SPBC; SPBC/UA; BCS; BCS/UA; EBC; EBC/UA; BR; and BR/UA. Setting time was performed based on ISO 6876:2012 and ASTM C266-07 specifications. Solubility at 24hs, based on ISO 6876:2012. pH and calcium release were evaluated at 1, 24, 72, and 168hs. Raman spectroscopy was used to evaluate structural changes. Quantitative data were analyzed using One-Way ANOVA and Tukey post-hoc test (α=5%). Raman spectroscopy results were qualitatively analyzed. Setting times and solubility of all sealers were not affected by UA (p>0.05). The highest solubility was found for BCS, BCS/UA; and BR, BR/UA (p<0.05). After 24hs, calcium silicate sealers had higher pH than SP and SP/UA (p<0.05). BR and BR/UA had the highest pH at all time points. SP and SP/UA had stable pH at all time points. SP and SP/UA had the lowest calcium release values at all time points (p<0.05). EBC and EBC/UA calcium release significantly differ at 24,72 and 168hs (p<0.05). No chemical changes were observed during Raman spectroscopy. In conclusion, ultrasonic activation affected calcium ion release only for EndoSequence BC Sealer. Ultrasonic activation did not influence the initial and final setting time, solubility, pH, and chemical structure of any investigated sealers.

Influence of sealer and supplementary approach on filling material removal during endodontic retreatment

Both root canal sealer-based and supplementary protocols may influence removal of filling material during endodontic retreatment. Mesial root canals of extracted mandibular molars were prepared using HyFlex EDM 25/.08, and filled with a calcium silicate sealer (Bio-C Sealer), or an epoxy resin (AH Plus), using the single cone technique (n = 12). Retreatment was performed using ProDesign Logic (PDL) RT and PDL 35/.05. The specimens were randomly divided into two experimental groups (n = 12), and the sealers were distributed similarly. A supplementary protocol was performed with PDL 50/.01 or XP-endo Finisher. Root canal transportation and volume, in addition to the remaining filling material percentage were evaluated using high-resolution (5 µm voxel size) micro-CT. Statistical analysis was performed using t-tests (α = 0.05). Root canals filled with AH Plus presented high residual filling material (p < 0.05). Both protocols decreased residual volume of filling material in the apical third (p < 0.05). PDL 50/.01 increased the apical root canal volume (p < 0.05). No difference was observed between the systems regarding canal transportation (p > 0.05). In conclusion, AH Plus is more difficult to remove from the apical third than Bio-C Sealer. PDL 50/.01 and XP-endo Finisher enabled greater removal of filling materials in the apical third, in the retreatment of curved root canals, without promoting apical transport.

Mechanical and Physicochemical Characteristics of a Novel Premixed Calcium Silicate Sealer

The aim of the present in vitro study was to evaluate specific mechanical and physicochemical properties of three calcium silicate-based sealers, BioRoot™ Flow (BRF), CeraSeal (CRS) and TotalFill® (TF). Samples were prepared to evaluate different physicochemical and mechanical properties of the tested sealers. These evaluations were accomplished by investigating the pH changes over time, porosity, roughness, flow properties, compressive strength and wettability. The results were statistically evaluated using one-way analysis of variance. All three sealers demonstrated an alkaline pH from 1 h of immersion in water to 168 h. A higher porosity and hydrophily were detected in BRF samples compared to CRS and TF. No significant difference was found between the tested materials in the flow properties. Lower compressive strength values were observed for BRF compared to TF and CRS. Differently shaped structures were detected on the three materials after 7 days of immersion in PBS. The three materials demonstrated a higher solubility than 3% after 24 h of immersion in water (CRS < BRF < TF). The novel premixed calcium silicate sealer (BRF) had comparable physicochemical properties to the existing sealers. The lower compressive strength values could facilitate the removal of these materials during retreatment procedures. Further studies should investigate the biological effects of the novel sealer.

Solcia AB, Guerreiro-Tanomaru JM, Tanomaru-Filho M, Faria G. Evaluation of Solubility, and Volumetric and Morphological Alterations of Bioceramic Filling Material for Primary Teeth: A New Methodological Approach

Objective

To evaluate the solubility and the volumetric and morphological alterations of bioceramic filling material (Bio-CP) for primary teeth.

Materials and Methods

Bio-CP, Calen thickened with zinc oxide (Calen-ZO), and with zinc oxide eugenol (ZOE) were placed in 1- or 2-mm-diameter polyethylene tubes and immersed in water or phosphate-buffered saline (PBS) for 30 days. The solubility (mass loss) was assessed using methodology modified from ISO 6876. Filling capacity, volumetric changes, and presence of voids were assessed by microcomputed tomography (micro-CT). The surface distribution of the chemical elements and the crystalline phases was evaluated by energy scattering X-ray scanning electron microscopy (SEM-EDX) and X-ray diffraction (XRD) to detect hydroxyapatite precipitate and components. The Shapiro-Wilk, Kruskal-Wallis, and Dunn's or two-way ANOVA and Tukey post hoc test were used (α = 0.05).

Results

The solubility was ZOE > Calen-ZO = Bio-CP. Calen-ZO and Bio-CP were more soluble in water than in PBS. All the materials showed greater solubility in 2-mm tube diameter in both PBS and distilled water, except for Bio-CP in distilled water, which showed no difference between both tube diameters (1 and 2 mm). Only Calen-ZO and ZOE were analyzed by micro-CT, because Bio-CP separated into two phases during scanning. Calen-ZO had greater volumetric loss and presence of voids than ZOE in water, but there was no difference in PBS. The hydroxyapatite precipitate on the surface of Bio-CP and Calen-ZO was detected after immersion in PBS.

Conclusion

Although Bio-CP had acceptable solubility and filling capacity, its composition did not allow a proper volumetric and void assessment. From a clinical perspective, Bio-CP has the potential to become a suitable material for root canal filling in primary teeth. Nonetheless, its composition must first be revised to achieve better chemical stability prior to its recommendation.

Biological properties versus solubility of endodontic sealers and cements

Endodontic sealers and cements used in root canal treatment have different compositions and properties. Common to all materials is that their primary goal is to fill gaps and voids, making a permanent seal of the root canal system. Furthermore, aspects such as antibacterial properties, cytotoxicity, setting time, solubility and biocompatibility are also crucial and ought to be considered. Over the years, a shift in the view on the importance of these aspects has ocurred. Whereas the antibacterial properties were considered important when the technical factors in endodontics were less developed, the sealing ability and biocompatibility have later been considered the most critical factors. The introduction of tricalcium silicate cements and sealers has led to a renewed interest in material properties, as these cements seem to have good sealing ability and at the same time combine favourable antimicrobial effects with excellent biocompatibility. This review discusses how the various properties of root canal sealers and cements may conflict with the primary aim of providing a permanent seal of the root canal system.

Effect of pH on the solubility and volumetric change of ready-to-use Bio-C Repair bioceramic material

Acidic pH can modify the properties of repair cements. In this study, volumetric change and solubility of the ready-to-use bioceramic repair cement Bio-C Repair (BCR, Angelus, Londrina, PR, Brazil) were evaluated after immersion in phosphate-buffered saline (PBS) (pH 7.0) or butyric acid (pH 4.5). Solubility was determined by the difference in initial and final mass using polyethylene tubes measuring 4 mm high and 6.70 mm in internal diameter that were filled with BCR and immersed in 7.5 mL of PBS or butyric acid for 7 days. The volumetric change was established by using bovine dentin tubes measuring 4 mm long with an internal diameter of 1.5 mm. The dentin tubes were filled with BCR at 37°C for 24 hours. Scanning was performed with micro-computed tomography (micro-CT; SkyScan 1176, Bruker, Kontich, Belgium) with a voxel size of 8.74 µm. Then, the specimens were immersed in 1.5 mL of PBS or butyric acid at and 37 °C for 7 days. After this period, a new micro-CT scan was performed. Bio-C Repair showed greater mass loss after immersion in butyric acid when compared with immersion in PBS (p<0.05). Bio-C Repair showed volumetric loss after immersion in butyric acid and increase in volume after immersion in PBS (p<0.05). The acidic pH influenced the solubility and dimensional stability of the Bio-C Repair bioceramic cement, promoting a higher percentage of solubility and decrease in volumetric values.

Physical-chemical properties and acellular bioactivity of newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer

OBJECTIVES

To evaluate the physiochemical properties and apatite-forming ability of a newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer (C3S-BG-P) and compare its results with the Nishika BG canal sealer and BioRoot™ RCS.

METHODS

The physicochemical properties (setting time, flow, solubility, film thickness, and radiopacity) of C3S-BG-P, Nishika BG canal sealer, and BioRoot™ RCS were evaluated in accordance with ANSI/ADA 57/2000 (reaffirmed 2012) and ISO 6876:2012 for root canal sealing materials. The in vitro apatite-forming ability was evaluated after 28 days of immersion of disc-shaped specimens in phosphate-buffered saline (PBS) using field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy.

RESULTS

The results of physiochemical tests indicated that all the tested sealers complied with the ADA and ISO standards; however, the solubility of the BioRoot did not meet the two standards. C3S-BG-P revealed significantly superior properties in all physicochemical tests compared to Nishika and BioRoot; however, the solubility of Nishika was significantly lower than that of C3S-BG-P. Furthermore, all tested sealers exhibited apatite precipitation on their surfaces after 28 days of immersion in PBS.

CONCLUSIONS

C3S-BG-P had superior physicochemical properties, which mitigated the disadvantages of calcium silicate-based sealers. Moreover, it exhibited apatite precipitation after immersion in PBS. Further in vivo studies utilizing animal models or clinical studies are necessary to support the rationale of the newly developed sealer for clinical application.

Evaluation of Cytotoxicity, Cell Attachment, and Elemental Characterization of Three Calcium Silicate-Based Sealers

We investigated three calcium silicate-based sealers with respect to their chemical characterization, cytotoxicity, and attachment to RAW264.7 cells. BioRoot RCS (BR), Bio-C Sealer (BC), and Sealer Plus BC (SPBC) were assessed using Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence spectroscopy (XRF), and energy-dispersive X-ray spectroscopy (EDX) (n = 4) for elemental characterization, and using scanning electron microscopy (SEM) to evaluate cell morphology and adhesion. Cytotoxicity was determined at different dilutions (1:1, 1:2, and 1:5) using the succinate dehydrogenase activity (MTT assay). Statistical analysis was performed for normal distribution using the Shapiro-Wilk test and for homoscedasticity using Levene's test, and one-way ANOVA, Tukey's/Dunnett's post hoc tests for cell viability and XRF (α = 0.05). Calcium silicate hydrate and calcium hydroxide were detected by FTIR in all groups. EDX detected a higher calcium content for BR and SPBC and aluminum only in the premixed sealers. XRF detected the highest calcium release in BR (p < 0.05). The surface morphology showed irregular precipitates for all the sealers. SPBC at a 1:2 dilution resulted in the lowest cell viability compared to BR (p < 0.05) and BC (p < 0.05). The calcium silicate-based sealers produced a statistically significant reduction in cellular viability at a 1:1 dilution compared to the control group (p < 0.0001). All the sealers maintained viability above 70%.

Characterisation of the Bioactivity and the Solubility of a New Root Canal Sealer

OBJECTIVES

This study aimed to analyse the effect of using phosphate buffer solution (PBS) on the solubility, pH changes, surface structure, and elemental composition of a new bioceramic Cerafill sealer compared with Endosequence sealer and AH26 resin-based sealer.

METHODS

A fresh mixture of each sealer moistened with either deionised water or PBS was subjected to a setting time test. Set discs (n = 10) were submerged in either deionised water or PBS to evaluate pH changes and solubility at 1, 7, 14, 21, and 28 days. Surface characterisation of the sealers was done before and after solubility tests using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and Fourier transform infrared (FTIR) spectroscopy analyses.

RESULTS

An analysis of variance revealed a significant delay in setting of BC-Endosequence (P < .001) with no significant difference when each sealer was moistened with deionised water or PBS (P > .05). Both bioceramic sealers exhibited highly alkaline pH (range, 9.47-10.72). When the sealer was submerged in deionised water, Endosequence exhibited significantly greater solubility, whilst Cerafill and AH26 gained weight. When the sealers were submerged in PBS, both bioceramic sealers gained more weight, with significantly greater values for Endosequence (P < .001). Hydroxyapatite formation was revealed by SEM/EDX and FTIR.

CONCLUSIONS

PBS promoted the formation of hydroxyapatite crystals that protect the bioceramic sealers from dissolving.

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.

pH influences the volumetric change of calcium silicate- and epoxy resin-based root canal sealers: An ex vivo micro-CT study

This study assessed the influence of pH variation on the volumetric change of EndoSequence BC Sealer compared to AH Plus Jet. Eighteen single-rooted teeth were uniformly prepared and filled with one of the sealers. After 24-h storing, samples were scanned in a micro-CT device. Then, roots were immersed in 20 ml phosphate-buffered saline (PBS) with pH of 5, 7 or 12 at 37°C for 7 and 30 days and rescanned. Statistical analysis was performed using Shapiro-Wilk's test, one-way ANOVA and Tukey's or Student's t-tests (p < 0.05). Differences between sealers were observed only at neutral pH and after 30 days of acidic pH exposure, with a higher loss of EndoSequence (p < 0.05). After 7 days, alkaline pH reduced and increased the volumetric loss of EndoSequence and AH Plus, respectively, compared to neutral pH (p < 0.05). It can be concluded that the pH directly influenced the volumetric change of both tested root canal sealers in different ways.

Volumetric changes in root canal sealers in ex vivo and a novel animal model approach

AIM

This study aimed to evaluate the volumetric change of root canal sealers through micro-computed tomographic analysis using a novel in vivo model and to compare the results with those obtained using an ex vivo test.

METHODOLOGY

Eighteen single-rooted teeth were cut to 5 mm length from the root apex. The root canals were uniformly enlarged and filled with EndoSequence BC Sealer or AH Plus Jet root canal sealers. Samples were stored at 37°C and 95% relative humidity for 24 h and then scanned with a micro-CT device. Twelve samples (n = 6 for each sealer) were implanted in the subcutaneous tissue of Wistar rats, while six samples (n = 3 for each sealer) were immersed in 20 mL of phosphate-buffered saline (PBS) at 37°C at neutral pH. After 7 and 30 days, teeth were removed from subcutaneous tissue or PBS and rescanned. Statistical analysis of volume changes was performed using Shapiro-Wilk's test and independent t-test (p < .05).

RESULTS

AH Plus Jet had smaller volume changes (-2.2 to +0.77%) than EndoSequence BC Sealer (-2.0 to +4.0%) (p < .05), in the two tested models. The volume of the root canal sealers decreased over time (p < .05), in vivo. AH Plus Jet results varied between the in vivo and ex vivo results (p < .05), while EndoSequence BC Sealer presented similar volume losses for both experimental models (p > .05).

CONCLUSION

EndoSequence BC Sealer lost more volume than AH Plus Jet. The experimental conditions influenced the volumetric change of AH Plus Jet but not the EndoSequence BC Sealer. The ex vivo model should be further explored as a methodological alternative to assess the volumetric changes of root canal sealers without causing harm to animals.

The Washout Resistance of Bioactive Root-End Filling Materials

Fast-setting bioactive cements were developed for the convenience of retrograde fillings during endodontic microsurgery. This in vitro study aimed to investigate the effect of irrigation on the washout of relatively fast-setting materials (Biodentine, EndoCem Zr, and MTA HP) in comparison with MTA Angelus White and IRM in an apicectomy model. Washout resistance was assessed using artificial root ends. A total of 150 samples (30 for each material) were tested. All samples were photographed using a microscope, and half of them were also scanned. The samples were irrigated and immersed in saline for 15 min. Then the models were evaluated. Rinsing and immersing the samples immediately after root-end filling and after 3 min did not disintegrate the fillings made of all tested materials except Biodentine. Root-end fillings made of Biodentine suffered significant damage both when rinsing was performed immediately and 3 min after the filling. Quantitative assessment of washed material resulted in a slight loss of IRM, EndoCem MTA Zr, and MTA HP. MTA Angelus White showed a slightly greater washout. Rinsing and immersion of Biodentine restorations resulted in their significant destruction. Under the conditions of the current study, the evaluated materials, excluding Biodentine, showed good or relatively good washout resistance.

A critical review of the material properties guiding the clinician's choice of root canal sealers

OBJECTIVES

The introduction of hydraulic cement sealers has increased the popularity of single cone obturation where the chemistry and properties of hydraulic cement sealers are crucial. This article has investigated the materials present on the market by reviewing the chemistry aiming at understanding whether these materials are optimized or have been tested appropriately.

METHODOLOGY

A market search on materials called bioceramic and hydraulic sealers was undertaken. The safety data sheet and manufacturer details for every material were searched and the components were checked. The literature was searched for information about the properties of these materials based on their composition.

RESULTS

The safety data sheets and manufacturer details were imprecise with some manufacturers providing little detail on composition. From the publications reviewed, it is apparent that the materials used clinically are not optimized, and there is little evidence that the material chemistry and presentation aid the clinical technique in any way.

CONCLUSIONS

There has been a rapid increase in materials identifying as bioceramics on the market. These materials have diverse chemistries, and some of the constituents are not declared. This may affect the clinical performance of these materials.

CLINICAL SIGNIFICANCE

Smart materials developed on the clinical need which are appropriately tested are necessary for a paradigm shift in root canal obturation. It is important to use reputable materials that have been adequately researched in clinical practice.

The effects of heating on the physicochemical properties of tricalcium silicate root canal sealers

This study evaluated the effect of heating on the physicochemical properties and surface changes of tricalcium silicate sealers. Three tricalcium silicate root canal sealers (Bio-C Sealer, BioRoot-RCS, EndoSequence BC Sealer), and one epoxy resin-based sealer (AH Plus; control) were tested. The effect of heating on setting time (ST) and flowability were assessed according to ANSI/ADA 57 and ISO 6876 standards. Solubility and dimensional change (DC) of the set sealers were evaluated at 24 hours and after 30 days; the pH of the water used in the DC testing was also measured. Tests were repeated with heated sealers in an oven at 100 °C for 1 min. SEM and EDS analysis were performed. Data were analyzed using One-Way ANOVA and Tukey post-hoc tests (α=5%). Heating decreased the ST for AH Plus and EndoSequence (p<0.05). Heating reduced flowability (p<0.05) and increased pH for AH Plus (p<0.05). The solubility of Bio-C (dried specimens) was not in accordance with the ANSI/ADA standard. The solubility of EndoSequence was significantly higher (p<0.05) when it was heated and dried after 30 days. DC of Bio-C (24 h and 30 days), BioRoot-RCS (30 days) and AH Plus (24 h and 30 days) were not in accordance with the standards. SEM and EDS analysis showed significant changes in sealer microstructure after heating. In conclusion, heating decreased the ST and increased the solubility of EndoSequence BC sealer. No significant changes in flowability, DC, and pH were identified for all three tricalcium silicate sealers after heat application. However, all sealers had significant surface changes.

Volume and power of expansion of novel polyurethane-based sealers

INTRODUCTION

Shrinkage and lack of interfacial adaptation between endodontic sealers and root canal walls may jeopardize the root canal treatment outcome. This study aimed to evaluate the volume and power of expansion (and the relationship between the two) of three novel root canal sealers (polyurethane expandable sealer (PES), zeolite + PES (ZPES), and elastomeric polyurethane sealer (EPS)) in comparison with an epoxy-resin based sealer (AH Plus) and a calcium silicate-based sealer (EndoSequence BC).

METHODS

This study utilized 36 cylinders (30 plastic graduated cylinders for volume of expansion and 6 steel cylinders for power of expansion) (4x10mm) filled with PES, ZPES, EPS, AH Plus, EndoSequence BC, or water (n=5/group). The plastic graduated cylinders were inserted inside a customized Linear Swell Meter (LSM) apparatus to measure the percentage of volumetric expansion. The steel cylinders were placed inside an LSM apparatus mounted onto a universal testing machine to measure the maximum pressure in psi. Specimens were tested for 72 hours for both volume and power of expansion tests. Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, Post Hoc Tukey, and Pearson correlation tests (p<0.05).

RESULTS

The volume of expansion of PES, ZPES, and EPS was significantly higher than in AH Plus and EndoSequence BC (p<0.05). For the power of expansion, no significant differences were found between the root-filling materials (p>0.05). No correlation was seen between the volume and power of expansion (p>0.05).

CONCLUSION

Although polyurethane-based sealers showed a significantly higher volume of expansion compared to AH Plus and EndoSequence BC, their power of expansion did not increase significantly.

Clinical applications of calcium silicate-based materials: a narrative review

Calcium silicate-based materials are hydrophilic materials with biocompatibility and bioactivity properties. Despite many advantages, they might present some problems related to discolouration, setting time, manipulation and solubility depending on the composition of the product and the type of clinical application. Calcium silicate-based materials can be evaluated under two types according to their intended use: calcium silicate-based cements (CSCs) and calcium silicate-based sealers (CSSs). CSCs can be used in many endodontic procedures including perforation repair, resorption repair, apical barriers, guided endodontic repair, vital pulp treatment, endodontic surgery, root fractures and root canal filling as a core obturation material. CSSs are available for use with gutta-percha to obturate root canals using cold and warm techniques, including the sealer-based obturation technique. The purpose of this review is to evaluate the available literature on CSCs and CSSs and to provide up-to-date information and recommendations for their clinical applications.

In vitro inflammatory modulation of bioceramic endodontic sealer in macrophages stimulated by bacterial lipopolysaccharide

AIM

To evaluate the effects of AH Plus (Dentsply), Sealer 26 (Dentsply), and Sealer Plus BC (Produtos Médicos e Odontológicos) on cytotoxicity and inflammation in macrophage cultures exposed to bacterial lipopolysaccharide (LPS).

METHODOLOGY

After initial setting, the sealers were conditioned with serum-free culture medium for 24 h (1 ml/cm² ). Macrophages from the RAW 264.7 strain were exposed to sealer extracts in a 1:16 ratio in a culture medium with or without LPS. Cell morphology, viability, mitochondrial activity, oxidative stress and gene expression of interleukin 1β (IL-1β) and tumour necrosis factor-alpha (TNF-α) were evaluated. Data on mitochondrial activity, oxidative stress and TNF-α were analysed using a two-way analysis of variance (anova) test, followed by the Student-Newman-Keuls post-test. IL-1β data were analysed using one-way anova, followed by SNK, and the t-test was used for intragroup comparison. The significance level was set at 5%.

RESULTS

In the absence of LPS, only AH Plus and Sealer 26 showed a reduction in cell density, while in the presence of LPS, Sealer 26 had the lowest density compared to the other groups. In terms of mitochondrial activity, at 24 and 48 h, Sealer Plus BC had significantly higher mean values than Sealer 26 and AH Plus (p < .05). Sealer 26 exhibited the lowest levels of oxidative stress and IL-1β and TNF-α expression, regardless of the presence of LPS (p < .05).

CONCLUSIONS

Although all sealers interfere with the response of macrophages to LPS, contact with epoxy resin-based sealers can impair cell activity in vitro, while bioceramic sealer seems to favour the inflammatory functions of these cells.

Cytotoxicity evaluation of Bio-C, CeraSeal, MTA - Fillapex, and AH Plus root canal sealers by microscopic and 3-(4, 5 dimethythiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay

Aim

The aim of this study was to compare the cytotoxic effect of calcium silicate-based Bio-C, CeraSeal, and mineral trioxide aggregate (MTA)-based (MTA-Fillapex) sealers to a widely used resin-based sealer (AH Plus) using 3-(4, 5 dimethythiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and microscopic examination.

Materials and Methods

A total of (n = 36) samples divided into four groups with three sealer samples per time period of 0 h, 24 h, and 7 days after mixing were extracted in cell culture medium using Dulbecco's Modified Eagle's Medium. The cytotoxicity of these sealers was evaluated using an MTT assay on L929 mouse fibroblasts, and changes in the cell morphology were observed under an inverted phase-contrast microscope (×20). The values obtained were analyzed statistically using one-way ANOVA, Tukey's post hoc, and Bonferroni's test.

Results

Bio-C and CeraSeal showed a reduction in cytotoxicity from severe at 0 h to no cytotoxicity at 24 h and 7 day time period. AH Plus showed severe cytotoxicity at all time periods. MTA-Fillapex showed severe cytotoxicity at 0 h which decreased to moderate at 24 h and 7 days. The differences between groups were statistically significant (P < 0.05).

Conclusions

The sealers with resin constituents (AH Plus and MTA-Fillapex) showed severe-to-moderate cytotoxicity at different time periods, whereas calcium silicate-based sealers (Bio-C and CeraSeal) were relatively biocompatible as their cytotoxicity decreased significantly from severe initially to noncytotoxic with time.

Physicochemical properties, cytotoxicity and bioactivity of a ready-to-use bioceramic repair material

The aim of this study was to evaluate the physicochemical properties, cytotoxicity and bioactivity of a ready-to-use bioceramic material, Bio-C Repair (Angelus), in comparison with White MTA (Angelus) and Biodentine (Septodont). The physicochemical properties of setting time, radiopacity, pH, solubility, dimensional and volumetric changes were evaluated. Biocompatibility and bioactivity were assessed in Saos-2 osteoblast cell cultures by the MTT assay 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), Neutral Red (NR), Alizarin Red (ARS), and cell migration tests. Statistical analysis was performed by ANOVA, Tukey or Bonferroni tests (α = 0.05). Bio-C Repair had the longest setting time (p < 0.05), but radiopacity and solubility were accordance with the ISO 6876/2012 standards, besides linear expansion. Bio-C Repair and MTA had similar volumetric change (p > 0.05); lower than Biodentine (p < 0.05). All the materials evaluated had an alkaline pH. Bio-C Repair was cytocompatible and promoted mineralized nodule deposition in 21 days and cell migration in 3 days. In conclusion, Bio-C Repair had adequate radiopacity above 3mm Al, solubility less than 3%, dimensional expansion, and low volumetric change. In addition, Bio-C Repair promoted an alkaline pH and presented bioactivity and biocompatibility similar to MTA and Biodentine, showing potential for use as a repair material.

Mechanism of action of Bioactive Endodontic Materials

A continuous search for bioactive materials capable of supporting the replacement of damaged pulp tissue, with effective sealing potential and biocompatibility, has represented the attention of studies over the last decades. This study involves a narrative review of the literature developed by searching representative research in PUBMED/MEDLINE and searches in textbooks associated with the mechanism of action of bioactive materials (calcium hydroxide, mineral trioxide aggregate (MTA), and calcium silicate cements). The reflective analysis of the particularities of the chemical elements of these materials, considering the tissue and antibacterial mechanism of action, allows a better understanding of the characteristics and similarities in their tissue responses. Calcium hydroxide paste remains the antibacterial substance of choice as intracanal dressing for the treatment of root canal system infections. Calcium silicate cements, including MTA, show a favorable biological response with the stimulation of mineralized tissue deposition in sealed areas when in contact with connective tissue. This is due to the similarity between the chemical elements, especially ionic dissociation, the potential stimulation of enzymes in tissues, and the contribution towards an alkaline environment due to the pH of these materials. The behavior of bioactive materials, especially MTA and the new calcium silicate cements in the biological sealing activity, has been shown to be effective. Contemporary endodontics has access to bioactive materials with similar properties, which can stimulate a biological seal in lateral and furcation root perforations, root-end fillings and root fillings, pulp capping, pulpotomy, apexification, and regenerative endodontic procedures, in addition to other clinical conditions.

Physicochemical and Antibacterial Properties of Conventional and Two Premixed Root Canal Filling Materials in Primary Teeth

In this study, some physicochemical and antibacterial properties of three root canal filling materials for primary teeth, Calplus “CP” (Prevest DenPro, Lewes, DE, USA), Bio-C Pulpecto “Bio-CP” (Angelus, Basil, Londrina, Paraná, Brazil), and Zinc Oxide and Eugenol “ZOE” (Prevest DenPro, Lewes, DE, USA) were compared. For each material, the pH, solubility, contact angle, and crystalline microstructure under SEM were evaluated. Their antibacterial activity against Enterococcus faecalis was determined through direct tests. The Kruskal−Wallis test was used to analyze the results using a one-way analysis of variance on ranks. All the materials had an alkaline pH at 3, 24, and 72 h, with CalPlus having the highest (p < 0.05). Bio-CP was more soluble during the evaluation period (24 h) than ZOE and CalPlus (p < 0.05). Bio-CP and ZOE demonstrated the creation of crystallite structures on their surfaces after immersion in PBS at 37 °C, whereas CalPlus showed none. The lowest contact angle was observed for Bio-CP (53 ± 1.5°); contact angles of (86 ± 4°) and (96 ± 1°), respectively, were observed after 10 s of the deposition of the water drop for CalPlus and ZOE. In conclusion, according to this study, there is still a need to develop new filling materials for primary teeth. ZOE, CalPlus and Bio-CP demonstrated different physicochemical and antibacterial properties, but none of the materials had optimal properties and could be considered the most suitable filling material for primary teeth pulpectomy. Bioceramics in their current state are not an alternative. The physicochemical and antibacterial properties still need improvement to fit the intricate anatomy of primary teeth.

Micro-CT assessment of gap-containing areas along the gutta-percha-sealer interface in oval-shaped canals

AIM

To assess the interfacial adaptation (gap-containing areas) of two root canal sealers (EndoSequence BC Sealer and AH Plus) to a conventional gutta-percha (GP) cone (GP-sealer interface) in oval-shaped canals filled using the single cone technique.

METHODOLOGY

Sixteen teeth with oval-shaped canals were selected, scanned in a micro-computed tomographic device, and pair-matched according to the volume, aspect ratio and configuration of root canals. Root canals were then sequentially prepared with WaveOne Gold Primary and Large instruments, followed by filling with WaveOne Large GP points associated with either the premixed calcium-silicate EndoSequence BC Sealer or the epoxy resin-based AH Plus sealer (n = 8 per group) using the single cone technique. After 7 days stored in phosphate-buffered saline solution at 37°C, the specimens were rescanned and the reconstructed images segmented in order to differentiate the filling materials (sealer and GP cone) to the dentine. A total of 453 cross-sectional slices were assessed and categorized according to the presence or absence of gaps at the GP-sealer interface. Mann-Whitney U-test verified the differences between groups and were considered significant at alpha = 5%.

RESULTS

Gaps were non-homogenously distributed in two-dimensional axial cross-section images and none of the specimens showed completely gap-free areas along the entire GP-sealer interface. Root canals filled with EndoSequence BC Sealer and AH Plus displayed 171 (37.75%) and 136 (30.02%) slices with gaps in the GP-sealer interface and these frequencies were statistically significant (p = .000).

CONCLUSIONS

Although none of the specimens had a gap-free area along the entire GP-sealer interface, oval canals filled with AH Plus showed less gaps than the ones filled with EndoSequence BC Sealer.

Physicochemical properties and osteoclastogenesis for three premixed calcium silicate-based sealers post set

Solubility, pH, ion release, cytotoxicity, and osteoclastogenesis inhibition in bone marrow-derived monocyte macrophages (BMMs) were evaluated in EndoSequence BC Sealer (END), Bio-C Sealer (BC), and Sealer Plus BC (SPBC). pH was determined after immersion of the sealers in deionized water (DW) and Minimum Essential Medium Alpha (α-MEM). Solubility was obtained by mass loss. Ion release was measured by using X-ray fluorescence spectroscopy (XRF). Cytotoxicity was evaluated by MTT assay. Inhibition of osteoclastogenesis was evaluated by tartrate-resistant acid phosphatase (TRAP). Data were analyzed using the t-test, ANOVA and Tukey/Dunnett's post-hoc tests (α = 0.05). END had the highest pH in DW (p < 0.05), and BC, in α-MEM (p < 0.05). Solubility in DW was the lowest for SPBC (p < 0.005). The highest calcium release was observed for BC in DW at 12 h (p < 0.05), and in α-MEM at 12 and 24 h (p < 0.05). The lowest toxicity was detected for END (p < 0.05). BC had the highest inhibitory effect on osteoclasts (p < 0.05). Overall, the highest solubility and pH values were found in DW. However, the calcium silicate-based sealer showed higher solubility than the ISO standards. Calcium release was the highest for BC. END showed the highest cell viability, and BC, the highest osteoclast inhibition.

Methods for testing solubility of hydraulic calcium silicate cements for root-end filling

Regulatory testing of hydraulic cements used in dentistry and standard test methods for root-end filling materials do not exist. The aim of this study was to identify a simple, reproducible method for testing the solubility of materials that set with water (hydraulic) used as root-end filling materials in dentistry. Commercial and prototype hydraulic cements were characterized by scanning electron microscopy and X-ray diffraction analyses and their solubilities were determined using ISO 6876; 2012 standard, a modified ISO 6876 method with media alternative to water and a new method measuring the percentage mass loss and volume change of materials (micro-CT method) from a single surface exposed to three solutions. The solubility testing was performed by three operators to enable an intra-laboratory comparison. The solubility data obtained from the two commercial and two prototype materials varied depending on the method used, with the ISO 6876 method identifying differences in solubility of the materials (p < 0.05) but when modified with alternative solutions, no differences were found (p > 0.05). The changes in solution thus effected the solubility of the tested materials. Inter-operator differences were observed with the weight changes determined from the new method indicating this method was not robust. The weight and volume assessments using the new method were not solution-dependent. The advantage of the proposed method compared with the ISO standard is its simplicity, enabling a number of tests to be performed on the same set of samples that also more closely mimics the clinical environment.

Does ultrasonic activation improve the bond strength and root canal filling quality of endodontic sealers?

This study aimed to investigate the effect of ultrasonic activation (UA) of three endodontic sealers on the bond strength to root dentin and root canal filling quality. Ninety six bovine incisors were instrumented and root canal filling was carried out using AH Plus (AP), Sealer Plus (SP), or Sealer Plus BC (BC), with or without UA (n=16/group). Two 1.5-mm slices were obtained from each root third. The first slice was subjected to push-out testing and failure mode analysis, while the second was observed under a stereomicroscope for filling quality assessment. Data were analyzed by Kruskal-Wallis, Mann-Whitney and Friedman tests (α=0.05). SP showed higher bond strength and fewer voids than BC in the apical third and when root thirds data were pooled. SP also had higher bond strength compared with AH Plus in the apical third. UA improved the bond strength when BC was used but did not affect the filling quality of any sealer. There were no significant differences between the ultrasonically activated sealers regarding bond strength and filling quality. When root thirds were compared, the bond strength was similar along the root, but there was a tendency to worsen filling quality, with more voids, in the apical segment. In conclusion, UA was effective in increasing the bond strength of the calcium silicate-based sealer but did not improve its filling quality. For the epoxy resin-based sealers, these properties were not affected by UA.

Effect of chlorhexidine digluconate on antimicrobial activity, cell viability and physicochemical properties of three endodontic sealers

OBJECTIVE

Assess the biological and physicochemical properties of AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS) leachates with and without chlorhexidine (CHX).

METHODS

The sealers were studied in no contact and 1-minute contact with CHX. For biological properties (antibacterial activity and cytotoxicity), leachates were formed in saline of freshly mixed, 1-, 7- and 28 days set sealers. The antibacterial properties of sealer leachates were investigated for planktonic and biofilm growth of E. faecalis, S. mutans, S.epidermidis and S.aureus. The 3-(4,5 dimethylthiazolyl-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate murine fibroblast cell viability after exposure to the leachates. The physical properties (water uptake, sorption, solubility, porosity, surface characteristics) of sealers and the pH of the immersion liquid (saline or distilled water) were also assessed over a 28-days period.

RESULTS

CHX improved the antibacterial properties of the sealer leachates and reduced cell viability for all sealer leachates, except for freshly mixed PCS. BioRoot RCS leachates presented the highest antibacterial properties and cell viability with and without CHX contact. PCS was the material most affected by CHX in terms of physical properties, whereas for AH Plus, solubility was increased. CHX did not affect the physical properties of BioRoot RCS, except for solubility that was decreased. CHX contact did not change sealers' alkalinity in distilled water whereas it increased it for AH Plus and BioRoot RCS in saline.

SIGNIFICANCE

CHX improved the antibacterial efficacy of sealer leachates and either compromised or did not affect cell viability. CHX affected to various extent sealers' physicochemical properties.

Gafchromic™ EBT3 Film Measurements of Dose Enhancement Effects by Metallic Nanoparticles for 192Ir Brachytherapy, Proton, Photon and Electron Radiotherapy

Interest in combining metallic nanoparticles, such as iron (SPIONs), gold (AuNPs) and bismuth oxide (BiONPs), with radiotherapy has increased due to the promising therapeutic advantages. While the underlying physical mechanisms of NP-enhanced radiotherapy have been extensively explored, only a few research works were motivated to quantify its contribution in an experimental dosimetry setting. This work aims to explore the feasibility of radiochromic films to measure the physical dose enhancement (DE) caused by the release of secondary electrons and photons during NP–radiotherapy interactions. A 10 mM each of SPIONs, AuNPs or BiONPs was loaded into zipper bags packed with GAFCHROMIC™ EBT3 films. The samples were exposed to a single radiation dose of 4.0 Gy with clinically relevant beams. Scanning was conducted using a flatbed scanner in red-component analysis for optimum sensitivity. Experimental dose enhancement factors (DEFExperimental) were then calculated using the ratio of absorbed doses (with/without NPs) converted from the films’ calibration curves. DEFExperimental for all NPs showed no significant physical DE beyond the uncertainty limits (p > 0.05). These results suggest that SPIONs, AuNPs and BiONPs might potentially enhance the dose in these clinical beams. However, changes in NPs concentration, as well as dosimeter sensitivity, are important to produce observable impact.

Impact of Immersion Media on Physical Properties and Bioactivity of Epoxy Resin-Based and Bioceramic Endodontic Sealers

This study assessed the effects of immersion media [distilled water (dw), phosphate buffered saline (pbs) and simulated body fluid (sbf)] in the physical properties [fluid uptake/sorption/solubility and alkalinization activity (pH)] and bioactivity of a bioceramic sealer: the BioRoot RCS (BioRoot) (Septodont). The epoxy-resin sealer AH Plus (Dentsply) was used as comparison. Sealers were immersed in dw, pbs and sbf to evaluate the fluid uptake/sorption/solubility and pH’s media. Bioactivity was assessed with SEM/EDS, FTIR-ATR and XRD. BioRoot solubility was as follows: sbf > pbs = dw. BioRoot had alkaline pH, and AH Plus had neutral pH, regardless of the medium. BioRoot presented mineral precipitates and peaks indicating hydroxyapatite-precursors in pbs and sbf. AH Plus physical properties were not affected by immersion media and it had no bioactivity. pbs and sbf should be preferred to investigate bioceramic sealers over distilled water, because they were able to highlight the sealer properties. BioRoot maintained the alkaline environment and favored hard tissue deposition.

Impact of Water Solubility on Chemical Composition and Surface Structure of Two Generations of Bioceramic Root Canal Sealers

Aimed to evaluate the effect of water solubility on chemical properties and surface structure of bioceramic-based (BC-HiFlow and BC-EndoSeqence) compared with resin-based (Adseal) root canal sealers. Fresh mix was inserted into polyethylene mold (n = 10) and subjected to Vicat needle to evaluate the setting time. The set discs were analyzed by Fourier transform infrared (FTIR) spectroscopy then immersed in deionized water for 1, 7, 14 and 28 days. The solubility%, pH changes, released calcium (Ca2+), phosphate (PO43−) and silicon (Si4+) ions were evaluated after each immersion period. The discs were analyzed by scanning electron microscopy/Energy dispersed X-ray (SEM/EDX) before and after solubility test. Although FTIR detected similar composition of both bioceramic-sealers, BC-EndoSequence determined the prolonged setting times. At the end of solubility test, both bioceramic-sealers exhibited significant greater solubility (>3%), alkaline pH (>11) at p < 0.001. Adseal displayed the significant greatest Ca2+ and PO43− released, while BC-HiFlow displayed the significant greatest Si4+ release (p < 0.001). SEM revealed voids and pores on the surface of all tested sealers with the greatest value on Adseal surface. In conclusion, although both bioceramic-sealers had high solubility, BC-Hiflow complied the ISO standard regarding setting time and least surface micropores better than that of BC-EndoSequence.

Toxicity of bioceramic and resinous endodontic sealers using an alternative animal model: Artemia salina

Aims:

The present study assessed the toxicity of a novel calcium silicate-based root canal sealer (Bio-C Sealer) in comparison to Endosequence BC Sealer and AH Plus through a lethality assay involving brine shrimp (Artemia salina).

Methods:

Brine shrimp cysts were incubated for 24 h for the hatching of the larvae, which were then exposed to different concentrations (2.5, 5, 10, 20, 40, 80, and 100 μg/mL) of the test endodontic sealers for 24 h, followed by the determination of the survival rate.

Statistical Analysis Used:

One-way repeated-measures ANOVA and the Newman–Keuls post hoc test were used to compare the different materials as well as different concentrations of the same material. Dunnett's test was used to compare the different concentrations and different sealers to the control. The lethal concentration of each endodontic sealer necessary to kill 50% of the brine shrimp larvae (LC50) was also determined.

Results:

The toxicity of Bio-C (10, 20, 40, 80, and 100 μg/mL) and Endosequence BC Sealer (20, 80, and 100 μg/mL) was lower than that of AH Plus. No significant difference was found between Bio-C and Endosequence BC Sealer or among the different intragroup concentrations of these sealers. In the AH Plus group, concentrations ≥5.0 μg/mL exhibited greater toxicity compared to the concentration of 2.5 μg/mL and the control. AH Plus had the lowest LC50 (59.95 μg/mL), whereas Bio-C and Endosequence BC Sealer had LC50 values >200 μg/mL.

Conclusions:

Bio-C Sealer proved to be less toxic than AH Plus and exhibited similar toxicity to that of Endosequence BC Sealer.

Comparative evaluation of push-out bond strength of bioceramic and epoxy sealers after using various final irrigants: An in vitro study

Aim:

The aim of the study is to compare the push-out bond strength of bioceramic and epoxy sealers after using various final irrigants.

Materials and Methods:

Hundred single-rooted teeth were divided into two groups (n = 50) according to the sealer used: Group A: Bio C (bioceramic sealer), Group B: Dia-Proseal (epoxy sealer). Each group was subdivided into five subgroups (n = 10) according to the final irrigation protocol: Group A1 and B1 – 5% glycolic acid (GA), Group A2 and B2 – 17% GA, Group A3 and B3 – 0.2% chitosan, Group A4 and B4 – 17% ethylenediaminetetraacetic acid, and Group A5 and B5 – 0.9% saline. Samples were obturated in combination with one of the mentioned sealers and were allowed to set for 1 week. Two horizontal slices were obtained from each sample and subjected to push-out test.

Statistical Analysis:

The data were statistically analyzed using two-way ANOVA and independent Student's t-test.

Results:

Both the sealers exhibited higher push-out bond strength after treatment with GA with no significant difference between 5% and 17% GA. Bio C sealer with GA as final irrigant showed higher bond strength than Dia-Proseal (P < 0.05).

Conclusion:

The push-out bond strength of the sealer was significantly affected by the final irrigation solution used. The highest push-out bond strength was seen with Bio C sealer after treatment with GA with no significant difference between 5% and 17% GA.

Physicochemical and biological properties of new tricalcium silicate-based repair material doped with fluoride ions and zirconium oxide as radiopacifier

This study evaluated the physicochemical and biological properties of novel reparative materials composed of pure tricalcium silicate (Ca₃ SiO₅ ), Ca₃ SiO₅ doped with fluoride ions (Ca₃ SiO₅ -F) and their association with ZrO₂ (Ca₃ SiO₅  + ZrO₂ , Ca₃ SiO₅ -F + ZrO₂ ), in comparison with Biodentine (BIO). Setting time radiopacity, pH, solubility, and dimensional change were evaluated based on ISO 6876 Standard. Volumetric change and flow/filling were assessed by microcomputed tomography (micro-CT). Biological properties were evaluated by the MTT assay 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), Neutral Red (NR), cell migration, alkaline phosphatase activity (ALP), and Alizarin Red Staining (ARS) assays. Statistical analysis was performed by ANOVA, Tukey, or Bonferroni tests (α = .05). Ca₃ SiO₅ -F + ZrO₂ had higher radiopacity, shorter setting time, and lower solubility and volumetric loss than BIO (p < .05). Ca₃ SiO₅ -F + ZrO₂ had flow and filling capacity similar to BIO (p > .05). All the cements evaluated had an alkaline pH. Ca₃ SiO₅ -F + ZrO₂ demonstrated cell viability similar to negative control (p > .05), increase in ALP activity in 7 days, mineralized nodule production in 21 days and repair capacity according to cell migration. In conclusion, Ca₃ SiO₅ -F + ZrO₂ had adequate setting time, radiopacity, solubility, and dimensional change. This material presented low volumetric change besides flow and filling capacity in micro-CT assessment. In addition, Ca₃ SiO₅ -F + ZrO₂ was biocompatible and bioactive, suggesting its use as reparative material.

Calcium Silicate-Based Root Canal Sealers: A Narrative Review and Clinical Perspectives

Over the last two decades, calcium silicate-based materials have grown in popularity. As root canal sealers, these formulations have been extensively investigated and compared with conventional sealers, such as zinc oxide-eugenol and epoxy resin-based sealers, in in vitro studies that showed their promising properties, especially their biocompatibility, antimicrobial properties, and certain bioactivity. However, the consequence of their higher solubility is a matter of debate and still needs to be clarified, because it may affect their long-term sealing ability. Unlike conventional sealers, those sealers are hydraulic, and their setting is conditioned by the presence of humidity. Current evidence reveals that the properties of calcium silicate-based sealers vary depending on their formulation. To date, only a few short-term investigations addressed the clinical outcome of calcium silicate-based root canal sealers. Their use has been showed to be mainly based on practitioners' clinical habits rather than manufacturers' recommendations or available evidence. However, their particular behavior implies modifications of the clinical protocol used for conventional sealers. This narrative review aimed to discuss the properties of calcium silicate-based sealers and their clinical implications, and to propose rational indications for these sealers based on the current knowledge.

Evaluation of curved root canals filled with a new bioceramic sealer: A microcomputed tomographic study using images with different voxel sizes and segmentation methods

The aim of this study was to investigate the filling ability of a new premixed bioceramic sealer in comparison with an epoxy resin-based sealer in curved root canals using different segmentation methods and voxel sizes in micro-CT images. Twelve curved mesial roots of mandibular molars with two separated canals were selected. All root canals were prepared by using HyFlex EDM files size 25/.08 and filled by the single cone technique and Bio-C Sealer or AH Plus (n = 12). The samples were scanned by micro-CT at 5 μm. The images were analyzed at 5, 10, and 20 μm for the volumetric analysis of voids in filling. Visual image segmentation was performed by two examiners, and the automatic segmentation was accomplished for comparison. Radiopacity of the sealers was evaluated by radiographic analysis. Data were submitted to the two-way ANOVA and non-paired t tests at a significance level of 5%. AH Plus had the highest radiopacity (p < .05). Root canals filled with AH Plus or Bio-C had similar low percentage of voids (p > .05). There was no difference interobserver, which had similar results to those obtained with automatic segmentation for all voxel sizes evaluated (p > .05). Bio-C Sealer had appropriate filling ability. Visual and automatic segmentation can be applied to micro-CT images with voxel sizes from 5 to 20 μm to evaluate the filling of sealers with adequate radiopacity. Automatic segmentation should be used as a faster method.

Influence of variations in the environmental pH on the solubility and water sorption of a calcium silicate-based root canal sealer

AIM

To evaluate the influence of pH variation on the solubility and water sorption of a premixed calcium silicate-based root canal sealer (EndoSequence BC Sealer) compared to the gold standard based on epoxy resin (AH Plus Jet) after immersion in distilled water and phosphate-buffered saline (PBS).

METHODOLOGY

Solubility and water sorption were evaluated after immersion in distilled water or PBS at several pHs (5, 7 and 12) and the values were calculated as percentages of the original mass after 24 h, 7 and 30 days of immersion. The crystalline structures present in the sealers and surface precipitates were assessed by X-ray diffraction. The Shapiro-Wilk's test revealed that data were normally distributed; thus, statistical analysis was performed using one-way anova and Tukey's tests or independent t-test, assuming a 5% α-error.

RESULTS

EndoSequence BC Sealer was associated with significantly greater water sorption and solubility compared to AH Plus Jet in all tested conditions (P < 0.05). The acid environment increased the 24 h solubility of EndoSequence BC Sealer immersed in PBS (P < 0.05) and did not induce significative changes in the water sorption (P > 0.05). Alkaline pH reduced the solubility of EndoSequence BC Sealer and increased that of AH Plus Jet at all experimental times and soaking media (P < 0.05). Alkaline environment also significantly increased the water sorption of AH Plus Jet immersed in PBS (P < 0.05). Immersion in PBS significantly reduced the solubility of EndoSequence BC Sealer and significantly increased that of AH Plus Jet (P < 0.05). Precipitates on the surface of EndoSequence BC Sealer corresponding to hydroxyapatite and calcium carbonate were detected after immersion in PBS at pH 5 and 7 for 30 days.

CONCLUSIONS

EndoSequence BC Sealer had significantly greater solubility and water sorption than AH Plus Jet. Although the alkaline pH and soaking media directly influenced the solubility and water sorption of the sealers, the solubility of AH Plus Jet remained within the limits recommended by ISO 6876, whilst the solubility of the EndoSequence BC Sealer did not comply with ISO recommendations in all the conditions tested.

Effect of Different Dimensions of Test Samples on the Volumetric Change Assessment Of Endodontic Materials

New methodologies using micro-CT to evaluate solubility besides dimensional and morphological changes of endodontic materials are proposed. However, there is no standardization in the methods. The aim of this study was to assess the effect of different dimensions of test samples on volumetric change evaluation of different endodontic materials. AH Plus, FillCanal and Sealapex root canal sealers, Biodentine, IRM and MTA root-end filling cements were used in the tests. Samples of each material with a thickness of 1.5 mm and different diameters were manufactured: 6.3, 7.75, and 9.0 mm. The samples were scanned in micro-computed tomography (micro-CT) after setting and after 7 days of immersion in distilled water. The volumetric change was evaluated by means of the difference in the total volume of the specimens before and after immersion. Data were submitted to ANOVA and Tukey tests (p<0.05). The size of the samples did not affect the percentage of volumetric change of the materials (p>0.05). All sample sizes had greater volume loss for Sealapex among the sealers and Biodentine for the cements (p<0.05). In conclusion, Biodentine and Sealapex had the highest volume loss after immersion. Samples with 1.5 mm thickness, and diameters ranging between 6.3 and 9.0 mm can be used to assess the stability of endodontic materials using micro-CT without affecting the percentage of volumetric change.

A micro-computed tomographic study using a novel test model to assess the filling ability and volumetric changes of bioceramic root repair materials

Objectives

New premixed bioceramic root repair materials require moisture for setting. Using micro-computed tomography (micro-CT), this study evaluated the filling ability and volumetric changes of calcium silicate-based repair materials (mineral trioxide aggregate repair high-plasticity [MTA HP] and Bio-C Repair, Angelus), in comparison with a zinc oxide and eugenol-based material (intermediate restorative material [IRM]; Dentsply DeTrey).

Materials and Methods

Gypsum models with cavities 3 mm deep and 1 mm in diameter were manufactured and scanned using micro-CT (SkyScan 1272. Bruker). The cavities were filled with the cements and scanned again to evaluate their filling capacity. Another scan was performed after immersing the samples in distilled water for 7 days to assess the volumetric changes of the cements. The statistical significance of differences in the data was evaluated using analysis of variance and the Tukey test with a 5% significance level.

Results

Bio-C Repair had a greater filling ability than MTA HP (p < 0.05). IRM was similar to Bio-C and MTA HP (p > 0.05). MTA HP presented the largest volumetric change (p < 0.05), showing more volume loss than Bio-C and IRM, which were similar (p > 0.05).

Conclusions

Bio-C Repair is a new endodontic material with excellent filling capacity and low volumetric change. The gypsum model proposed for evaluating filling ability and volumetric changes by micro-CT had appropriate and reproducible results. This model may enhance the physicochemical evaluation of premixed bioceramic materials, which need moisture for setting.

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.

Solubility of bioceramic- and epoxy resin-based root canal sealers: A systematic review and meta-analysis

This systematic review and meta-analysis evaluated whether epoxy resin-based root canal sealers present an increased solubility than calcium silicate-based root canal sealers. A systematic search was performed in the following databases: PubMed, Science Direct, Scopus, Web of Science and Open Grey. The inclusion criteria consisted of in vitro studies that compared the solubility of epoxy resin-based and calcium silicate-based sealers. The quality assessment and data extraction of the selected articles were performed. The meta-analysis of the pooled data and the subgroups according to the root thirds were carried out using the RevMan software (P < 0.05). After the duplicate removal and eligibility criteria assessment, a total of 22 studies were included all of them were considered as having a low risk of bias. The meta-analysis demonstrated overall lower solubility of AH Plus. AH Plus presented lower solubility than Bio-C Sealer, BioRoot RCS, MTA Fillapex, Sealer Plus and Total Fill BC Sealer.