Dissolution, dislocation and dimensional changes of endodontic sealers after a solubility challenge: a micro-CT approach

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.

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.

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.

Evaluation of Cytotoxicity of Calcium Silicate-based Mineral Trioxide Aggregate Sealers: A Systematic Review of In Vitro Studies

AIM

This review aimed to evaluate the in vitro studies done with regard to the cytotoxicity associated with mineral trioxide aggregate (MTA)-based root canal sealers.

BACKGROUND

Root canal sealers are used during endodontic treatment as fillers to seal the gaps between the canal gutta-percha cone and canal walls. It is necessary to understand the cytotoxicity of these materials on human-derived cells as these materials interact with human cells periapically.

REVIEW RESULTS

Six in vitro studies were chosen for review. In these selected studies, along with MTA-based root canal sealers, other sealers were tested for cytotoxicity on human periodontal ligament (PDL) stem cells, human PDL fibroblasts, and human osteoblast cells. Regarding cytotoxicity, the studies were diverse, and most were based on 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazolium bromide) (MTT) assay. In general, the studies suggested that root canal sealers cause mild to severe cytotoxic effects and that several factors influence this effect, such as material setting time, concentration, and duration of exposure.

CONCLUSION

All studies in the review indicated that MTA. Fillapex must be used cautiously as it exhibited the highest cytotoxic effect compared to other MTA-based and non-MTA-based sealers.

CLINICAL SIGNIFICANCE

Endodontic sealers do serve the purpose of bridging the gaps between the gutta-percha cone and the canal wall but knowing its biocompatibility becomes important as the material is extruded beyond the apical foramen where it comes in contact with the surrounding tissues. The effect of sealers on the surrounding tissues affects the healing and prognosis of the treatment.

Analysis of porosity, sealer dissolution and apical extrusion of endodontic sealers: A micro computed tomography study

Aim

The aim of the study was to determine the porosity, dissolution and apical extrusion of AH Plus, MTA Fillapex and EndoSequence BC sealer after immersion in phosphate buffered saline (PBS) using microcomputed tomography (micro-CT).

Methodology

Forty-eight single-rooted teeth were selected. Gutta percha and one of the aforementioned root canal sealers was used for obturation using continuous wave technique. The specimens were scanned after obturation and after seven days of immersion in PBS, by using micro-computed tomography. Porosity, sealer dissolution and apical extrusion were calculated. Statistical analysis was done by using paired t-test, post hoc tukey test and Fischer exact test.

Results

Significantly higher percentage of porosity and dissolution of sealer in the apical 4 mm was found for MTA Fillapex and EndoSequence BC sealer than for AH Plus. The incidence of apical extrusion was significantly more in MTA Fillapex (56.25%), followed by EndoSequence BC (31.25%) and AH Plus (0%).

Conclusions

None of the three root canal sealers exhibited perfect three-dimensional obturation. The sealers manifested porosity, dissolution and apical extrusion to varying degrees both after obturation and after storage in PBS for 7 days.

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.

Comparison of obturation quality in natural and replica teeth root-filled using different sealers and techniques

OBJECTIVES

This study aims to assess the obturation efficacy of sealers placed with different techniques using microcomputed tomography (µCT) and assess the influence of µCT testing parameters on the obturation data obtained.

MATERIALS AND METHODS

Incisors and mesial roots of lower molars with standardized root length were scanned using µCT, and one tooth of each type was 3D printed in acrylic. Two obturation techniques (warm vertical and single cone) and 4 sealer types (AH Plus, BioRoot RCS, Totalfill BC, and Bio-C Sealers) were assessed following storage in Hank's balanced salt solution for 3 and 6 months by assessing gap and void volume percentages on both natural and replica incisor and molar roots. The storage solution was analysed to assess calcium ion leaching. The influence of temperature, tooth positioning, and moisture content of the teeth while µCT scanning was also investigated.

RESULTS

The obturation quality in the incisor group was the same using both natural teeth and replicas (p > 0.05). No changes in void volume were identified when comparing the same sealer using different obturation techniques. The premixed sealers used in single-cone obturation exhibited high void volume in the 3D printed replicas in the long term. The temperature, positioning, and moisture content of the teeth did not affect the outcome of µCT testing.

CONCLUSIONS

BioRoot RCS, Totalfill BC, and Bio-C Sealers are suitable for obturation of both complex and simple root canal systems using different obturation techniques with BioRoot RCS exhibiting the highest calcium ion release. 3D printed acrylic teeth can be used to assess the obturation quality in uncomplicated root canal systems. µCT parameters had no significant effect on the µCT measurement.

CLINICAL RELEVANCE

The single-cone obturation technique with hydraulic sealer is a simple technique that can be used for obturation of all root canal systems.

Effect of nanosized bioactive glass addition on some physical properties of biodentine

The aim of this in vitro study was to investigate some physical properties of Biodentine (BD) (Septodont, France) that has been modified by adding nanosized bioactive glass (nBG) particles to it in different ratios. The cement was modified by adding 1% (7 mg) and 2% (14 mg) nBG powder to BD. BD was used as the control group in its commercial form. A total of 240 cement samples (n = 80) were prepared according to the standard measurements for each test. Subsequently, tests to determine compressive strength, microhardness, initial setting time, and solubility of the samples were performed. The obtained data were statistically analyzed using one-way ANOVA and Tukey's HDS tests, and the significance level was found to be 0.05. The compressive strength values of the samples modified with 1% and 2% nBG were higher than those of the unmodified BD; however, no statistically significant difference was found between them [BD + nBG (2 wt%) ⩾ BD+nBG (1 wt%) ⩾ control BD], (p > 0.05). The microhardness values of the samples modified with 1% and 2% nBG were found to be significantly higher than those of the control group [BD + nBG (2 wt%) > BD+nBG (1 wt%) > control BD], p < 0.05. Initial setting times were determined as 14 min for unmodified BD, 13 min for BD + nBG (1 wt%), and 12 min for BD + nBG (2 wt%). The addition of nBG to BD significantly reduced the initial setting time of BD (p < 0.05). A significant decrease was observed in the solubility of the BD modified with nBG samples compared to that of the control group [control BD > BD+nBG (1 wt%) >BD+nBG (2 wt%)], p < 0.05. Within the limitations of this study, it was found that the addition of certain amounts of nBG to BD positively affected some physical properties of the cement. Future in vitro and in vivo studies should be performed to prove the clinical applicability of the cements used in this study.

Interleukin-6, tumor necrosis factor-α, and CD5 immunolabeling of new experimental endodontic sealer and repair material

The aim of this study was to evaluate the biocompatibility and immunoinflammatory response of the Sealepox and Sealepox-RP, based on interleukin (IL)-6, tumor necrosis factor (TNF)-α, and CD5 immunolabelling. The ProRoot MTA (PRMTA) was used for comparison. Polyethylene tubes (1.0-mm internal, 1.6-mm external diameter, and 10.0-mm length; ISO 10993) with or without (control) materials were randomly implanted in the dorsum of 35 rats (4 per rat). After 7, 15, 30, 60, and 90 days (n = 7), the tubes were removed for histological and immunohistochemical analysis. The Kruskal-Wallis and Dunn's test for non-parametric data and, ANOVA and Tukey test for parametric data were used (P < 0.05). Hematoxylin and eosin staining revealed that the concentration of inflammatory cells decreased over time with no differences between groups in all periods (P > 0.05). Regarding IL-6 immunostaining, there was no difference at 7 days (P > 0.05); all groups decreased over time, being faster for the PRMTA group and also, with no differences between groups in the last period (P > 0.05). For TNF-α, at 7 days there was no difference between groups (P > 0.05); there was an increase at 15 days for PRMTA and, at 30 and 60 days, for PRMTA and Sealepox compared to the control (P < 0.05). At 90 days, Sealepox RP showed the lowest immunostaining being similar to the control (P > 0.05). Regarding CD5 cells, at 7 days, there was high immunostaining for PRMTA compared to the control (P < 0.05); and significant reduction over time with difference for all groups at 30 and 60 days. (P < 0.05); Sealepox was similar to the control in all periods (P > 0.05). Sealepox RP showed the highest immunostaining at 15 days, being different from the control and PRMTA (P < 0.05); in the other periods it was similar to the control (P > 0.05). It can be concluded that Sealepox and Sealepox-RP were biocompatible and demonstrated similar immunoinflammatory response regarding IL-6, TNF-α, and CD5 compared to PRMTA.

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.

Applications of scanning electron microscopy and focused ion beam milling in dental research

The abilities of scanning electron microscopy (SEM) and focused ion beam (FIB) milling for obtaining high-resolution images from top surfaces, cross-sectional surfaces, and even in three dimensions, are becoming increasingly important for imaging and analyzing tooth structures such as enamel and dentin. FIB was originally developed for material research in the semiconductor industry. However, use of SEM/FIB has been growing recently in dental research due to the versatility of dual platform instruments that can be used as a milling device to obtain low-artifact cross-sections of samples combined with high-resolution images. The advent of the SEM/FIB system and accessories may offer access to previously inaccessible length scales for characterizing tooth structures for dental research, opening exciting opportunities to address many central questions in dental research. New discoveries and fundamental breakthroughs in understanding are likely to follow. This review covers the applications, key findings, and future direction of SEM/FIB in dental research in morphology imaging, specimen preparation for transmission electron microscopy (TEM) analysis, and three-dimensional volume imaging using SEM/FIB tomography.

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

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

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.

Physicochemical Properties, Cytocompatibility and Antibiofilm Activity of a New Calcium Silicate Sealer

The aim of this study was to evaluate the physicochemical properties, cytocompatibility and antibiofilm activity of a new calcium silicate-based endodontic sealer, Sealer Plus BC (MK Life, Brazil), in comparison with TotalFill BC Sealer (FKG Dentaire SA, Switzerland) and AH Plus (Dentsply, Germany). Setting time and flow were evaluated based on ISO 6876 standard. The pH was evaluated after different periods, and radiopacity by radiographic analysis (mmAl). Solubility (% mass loss) and volumetric change (by micro-CT) were assessed after 30 days of immersion in distilled water. Cytocompatibility was assessed by methyltetrazolium (MTT) and neutral red (NR) assays, after exposure of Saos-2 cells to the sealer extract for 24 h. An additional analysis was performed by using MTT assay after 1, 3 and 7 days of exposure of Saos-2 to the sealers 1:8 dilution extracts. Antibiofilm activity against Enterococcus faecalis and/or Candida albicans was evaluated by crystal violet assay and modified direct contact test. The physicochemical properties were analyzed using ANOVA/Tukey tests; MTT and NR data were analyzed by ANOVA and Bonferroni tests; the antimicrobial tests were analyzed by Kruskal-Wallis and Dunn tests (α=0.05). Sealer Plus BC had proper setting time, radiopacity, flow and alkalization capacity. Sealer Plus BC was significantly more soluble than AH Plus (p<0.05) and presented volumetric change similar to AH Plus and TotalFill BC (p>0.05). Sealer Plus BC presented antibiofilm activity and no cytotoxic effect. In conclusion, although Sealer Plus BC had higher solubility, this sealer showed proper physicochemical properties, cytocompatibility, and antibiofilm activity.

Long-term porosity and retreatability of oval-shaped canals obturated using two different methods with a novel tricalcium silicate sealer

OBJECTIVE

To evaluate the percentage volume of voids and gaps in oval-shaped canals obturated using two different methods with a tricalcium silicate-based sealer after short- or long-term storage. The long-term effect of storage on the efficiency of removing filling material was also investigated.

MATERIALS AND METHODS

Forty premolar teeth with oval-shaped canals were instrumented to Reciproc R25 and obturated using single cone obturation (SCO) or warm vertical compaction (WVC) techniques with gutta-percha and HiFlow sealer. The specimens were stored at 100% humidity and 37°C for 2 weeks or 6 months and scanned using micro-computed tomography. Initial retreatment was performed up to a Reciproc R40, and the operating time was recorded. The residual material in the canal received a supplementary procedure using XP-endo Finisher R (XPFR) files. After each retreatment procedure, the specimens were rescanned.

RESULTS

The percentage volume of voids and gaps in the SCO group was higher than that of the WVC group at both 2 weeks and 6 months (P < 0.05). The percentage volume of the filling material removed after initial retreatment and XPFR cleaning was significantly higher in the 6-month group than in the 2-week groups (P < 0.05). The proportion of the residual material decreased significantly when XPFR files were used, compared to the initial retreatment group (P < 0.05) in both storage times.

CONCLUSION

The efficiency of retreatment in the oval-shaped canal was closely related to the storage time rather than the filling technique using a tricalcium silicate sealer. The XPFR instrument proved effective in the removal of the remaining materials from the oval-shaped canal.

CLINICAL RELEVANCE

Obturation of the oval-shaped canal with TSBS using the SCO technique in the coronal area needs to be optimized. The retreatment was less efficacious in freshly filled canals than aged filled canals.

The evaluation of physical properties of a polyurethane expandable endodontic sealer: a preliminary study

Endodontic sealers play a vital role in providing 3-dimensional (3D) filling of complex root canal system (RCS). This study intended to compare the physical properties of a Polyurethane Expandable Sealer (PES), AH Plus and EndoSequence. Three properties including setting time, radiopacity and flow (rheology) were evaluated based on ISO 6876 standard. For evaluation of each of these physical properties, five samples from experimental groups: AH Plus, EndoSequence, PES (controlled expansion) and PES (high expansion) were used (n = 5). Data were analysed by one-way ANOVA and Post Hoc Tukey tests (a = 0.05). EndoSequence showed the longest setting time (P < 0.000); AH Plus showed that highest radiopacity (P < 0.000); and PES (high expansion) showed the highest flow (diameter and surface area) (P < 0.000). EndoSequence and PES (controlled expansion) showed promising and comparable physical properties to the AH Plus sealer in terms of flow, setting time and radiopacity.

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.

Contrast-enhanced nano-CT reveals soft dental tissues and cellular layers

AIM

To introduce a methodology designed to simultaneously visualize dental ultrastructures, including cellular and soft tissue components, by utilizing phosphotungstic acid (PTA) as a contrast-enhancement agent.

METHODOLOGY

Sound third molars were collected from healthy human adults and fixed in 4% buffered paraformaldehyde. To evaluate the impact of PTA in concentrations of 0.3%, 0.7% and 1% on dental soft and hard tissues for CT imaging, cementum and dentine-pulp sections were cut, dehydrated and stained with immersion periods of 12, 24 h, 2 days or 5 days. The samples were scanned in a high-resolution nano-CT device using pixel sizes down to 0.5 µm to examine both the cementum and pulpal regions.

RESULTS

Dental cementum and periodontium as well as odontoblasts and predentine were made visible through PTA staining in high-resolution three-dimensional nano-CT scans. Different segments of the tooth required different staining protocols. The thickness of the cementum could be computed over the length of the tooth once it was made visible by the PTA-enhanced contrast, and the attached soft tissue components of the interior of the tooth could be shown on the dentine-pulp interface in greater detail. Three-dimensional illustrations allowed a histology-like visualization of the sections in all orientations with a single scan and easy sample preparation. The segmentation of the sigmoidal dentinal tubules and the surrounding dentine allowed a three-dimensional investigation and quantitative of the dentine composition, such as the tubular lumen or the ratio of the tubular lumen area to the dentinal surface.

CONCLUSION

The staining protocol made it possible to visualize hard tissues along with cellular layers and soft tissues in teeth using a laboratory-based nano-CT technique. The protocol depended on both tissue type and size. This methodology offers enhanced possibilities for the concomitant visualization of soft and hard dental tissues.

Biocompatibility and immunolabeling of fibronectin and tenascin of resinous root canal sealersw

Aims:

The aim of this study was to evaluate the biocompatibility of resinous root canal sealers: Sealer 26, AH plus, and SK Seal Root Canal Sealer in the subcutaneous tissue of rats.

Subjects and Methods:

Twenty-four Wistar rats received polyethylene tubes containing the sealers and empty tubes as control (n = 6). After 7, 15, 30, and 60 days, animals were killed and polyethylene tubes were removed with the surrounding tissues. The specimens were embedded in paraffin, processed for hematoxylin-eosin and immunohistochemistry assessed for fibronectin (FN) and tenascin (TN).

Statistical Analysis Used:

Data were tabulated and analyzed via Kruskal–Wallis and Dunn's test (P < 0.05).

Results:

All groups induced a moderate inflammatory reaction after 7 and 15 days (P > 0.05); after 30 days, a mild inflammatory infiltrate was observed in control groups, and moderate in sealers groups (P > 0.05); all groups showed mild inflammatory infiltrate at 60 days (P > 0.05). Overall, the fibrous capsule was considered thick only on the 7^th day and became thin over time. All groups had expression for FN and TN in all analyzed periods, with high immunolabeling in sealers groups when comparing with the control group (P < 0.05).

Conclusion:

All sealers demonstrated biocompatibility and induced FN and TN expression.

Analysis of the physicochemical properties, cytotoxicity and volumetric changes of AH Plus, MTA Fillapex and TotalFill BC Sealer

Background

To evaluate the physicochemical properties and cytotoxicity of AH Plus, MTA Fillapex and TotalFill BC Sealer. Volumetric changes were also evaluating using micro-computed tomography (micro-CT).

Material and Methods

Radiopacity and flow were evaluated in accordance with the ISO 6876, while setting time was evaluated in accordance with the ASTM- C266-08 specifications. The release of Ca2+ ions and pH were measured with spectrophotometer and pH meter, respectively, after different time intervals (1h, 3h, 24h, 72h, 168h, and 360h). Cytotoxicity was evaluated by MTT reduction assay to check 3T3 cells viability at 24, 48 and 72 hours. Volumetric change was evaluated by micro-CT, by using 30 acrylic teeth, filled with gutta-percha cones and the tested root canal sealer. The samples were evaluated after 168h, 360h and 720h of immersion in distilled water. Data were statistically analyzed by one-way ANOVA and Tukey test or by Kruskal-Wallis and Dunn tests (P<0.05).

Results

MTA Fillapex and TotalFill BC Sealer showed lower radiopacity than AH Plus (P<0.05). The MTA Fillapex showed the highest flow, while AH Plus showed the lowest flow (P<0.05). The initial and final setting time of AH Plus were lower than MTA Fillapex and TotalFill BC Sealer (P<0.05). In general, TotalFill BC Sealer presented higher Ca2+ ion release and pH than the other tested sealers. TotalFill BC Sealer also showed overall lower cytotoxicity when compared to the other sealers. Volumetric change of AH Plus and TotalFill BC Sealer was lower than MTA Fillapex (P<0.05).

Conclusions

AH Plus, MTA Fillapex and TotalFill BC Sealer showed slight differences in the physicochemical properties and cytotoxicity, but all suitable for an endodontic sealer. However, AH Plus and TotalFill BC Sealer showed low volumetric changes when compared to MTA Fillapex.

Key words:Calcium silicate, cytotoxicity, physicochemical properties, micro computed tomography.

Effect of Sonic Agitation of a Binary Mixture of Solvents on Filling Remnants Removal as an Alternative to Apical Enlargement-A Micro-CT Study

BACKGROUND

This work aimed to evaluate the efficacy of sonic agitation of a binary mixture of solvents (methyl ethyl ketone/tetrachloroethylene) on filling remnants removal and compare the effects of solvent agitation with the enlargement to the next instrument size.

METHODS

Twenty-four mandibular incisors were prepared with ProTaper Next (X1, X2) and obturated with the single-cone technique and AH Plus sealer. The teeth were retreated with ProTaper Universal Retreatment and ProTaper Next and divided into two groups (n = 12) according to the final instrument (X3 or X4). All canals were submitted to a supplementary procedure consisting of a mixture of solvents-methyl ethyl ketone/tetrachloroethylene, agitated with EndoActivator. The volume of filling remnants was assessed through micro-computed tomography in the apical 5 mm. Statistical analysis was performed with a significance level of 5%.

RESULTS

The supplementary procedure of agitation of the solvent mixture was beneficial in both groups (p < 0.05). There were no statistically significant differences between canals re-prepared until X4 and canals re-prepared until X3 plus solvent (p > 0.05).

CONCLUSIONS

An additional step with a two-solvent solution potentiated by EndoActivator showed to be very effective for the removal of gutta-percha and resinous sealer remnants from apical root canals of mandibular incisors, avoiding further enlargement.

Cytotoxicity, antibacterial and physicochemical properties of a new epoxy resin-based endodontic sealer containing calcium hydroxide

Background

This study evaluated the cytotoxicity, antibacterial and physicochemical properties of a new epoxy resin-based endodontic sealer containing calcium-hydroxide Sealer Plus. AH Plus was used as a reference for comparison.

Material and Methods

Cytotoxicity evaluation was performed according to ISO-10993-5 specifications using MTT assay to check the 3T3 cells viability at 1- to 4-week periods. Antibacterial activity was evaluated using a direct contact test against Enterococcus faecalis. Radiopacity, solubility and flow evaluations were performed according to ISO-6876/2012 specifications. Setting time was assessed following the ANSI/ADA-standard-n.57. The pH level was measured at 3,24,48,72, and 168 hours. Data were statistically analyzed using t-test. The significance level adopted was P<0.05.

Results

AH Plus and Sealer Plus showed cytotoxic effects after 24 hours and 1 week of manipulation and become noncytotoxic after 2 weeks. No differences were observed in the cytotoxicity of both tested sealers (P>0.05). Direct contact results revealed that both freshly prepared sealers has antibacterial effects against Enterococcus faecalis. However, after 7 days both sealers had lost much of their antibacterial effects. Although AH Plus presented higher radiopacity and flow than Sealer Plus (P<0.05), both sealers showed minimum required values. No differences were observed in the solubility of both sealers (P>0.05). AH Plus showed a higher setting time when compared to Sealer Plus (P<0.05). AH Plus and Sealer Plus showed a neutral pH during all tested periods (P<0.05).

Conclusions

It can be concluded that Sealer Plus showed suitable properties to be used as an endodontic sealer, comparable with those obtained by AH Plus.

Key words:Cytotoxicity, root canal filling materials, root canal obturation.

Structural, fluoride release, and 3D interfacial adhesion analysis of bioactive endodontic sealers

The experimental bioactive sealers were synthesized by incorporating fluoridated-nano-bioactive glass (F-nBG; 2.5 and 5wt%) in AH Plus^® (Dentsply DeTrey, Konstanz, Germany) sealer and denoted as AH-FBG2.5 and AH-FBG5, respectively. Structural pattern, setting time, flowability, and water sorption analysis were performed. The fluoride release behavior was evaluated periodically over the course of 40 days using inductively coupled plasma optical emission spectroscopy. For sealing ability, post-extraction single-rooted teeth were obturated with sealers. The percentage of voids and sealing ability were evaluated periodically using micro-computed tomography (micro-CT) followed by push-out bond strength. The Fourier transform infrared spectra showed a change in peak height with an increase in the concentration of fillers. The setting time, flowability, and water sorption of experimental groups were within the acceptable clinical range. The fluoride release, sealing ability, and bond strength of experimental sealers were significantly high. The experimental sealers have potential to overcome sealing ability issues of sealers.

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

Objectives

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

Materials and Methods

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

Results

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

Conclusions

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

Evaluation of different root canal filling techniques in severely curved canals by micro-computed tomography

AIM

To fill the severely curved root canals with different filling techniques and to compare these techniques using micro-computed tomography (micro-CT).

MATERIALS AND METHODS

Sixty extracted mandibular first molars (degree of root canal curvature >25°) were selected. All samples were divided into four groups and filled with one of the following techniques: lateral condensation, single-cone, continuous-wave obturation, and core carrier. After they were scanned by micro-CT, the total area, filled area and void area of the root canal were calculated. The Mann-Whitney U and Kruskal-Wallis tests were used for statistical analysis (p < 0.05).

RESULTS

It was shown that significantly more filling material was used in the lateral condensation and core carrier technique groups at 2 and 5 mm than in the single-cone and continuous-wave obturation technique groups (p < 0.05). It was observed no statistically significant difference at 8 mm (p > 0.05).

CONCLUSION

No technique could completely fill in root canal. Regarding the coronal part, all techniques can be used for more effective filling as long as a good condensation is achieved. The use of a plugger with an optimal size according to the localisation of root canal curvature and the choice of a heat-resistant root canal sealer affects the success of the treatment in the thermoplastic techniques.

Evaluation of Dentin Adaptability of Fluoride Varnish as a Root Canal Sealer Using Scanning Electron Microscopy

Objectives:

This study aimed to assess the dentin adaptability of a certain type of fluoride varnish, as a novel root canal sealer, in comparison with AH-Plus sealer.

Materials and Methods:

Twenty-four extracted single-rooted, single-canal human permanent teeth with straight and fully formed roots and no internal calcification, resorption or cracks, were selected and decoronated such that the remaining root length was 14 mm in all teeth. Root canals were prepared using the Mtwo rotary file system according to the manufacturer’s instructions and filled with gutta-percha and either AH-Plus (n=12) or fluoride varnish (n=12) via the lateral compaction technique. Each root was then sectioned at 4 and 8 mm distances from the apex for evaluation under a scanning electron microscope (SEM). The gap size between the sealer and dentin was measured. Statistical analysis was performed using the Kolmogorov-Smirnov test and t-test with the significance level set at 0.05.

Results:

The mean gap size was 14.407±1.402 μm and 8.342±0.694 μm in the roots obturated with AH-Plus and fluoride varnish sealers, respectively. The t-test revealed a statistically significant difference (P<0.001) in this regard between the two groups.

Conclusion:

Fluoride varnish, as a root canal sealer, has a superior adaptation to dentinal canal walls compared to the AH-Plus sealer.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Dentinal Tubule Penetration and Dislocation Resistance of a New Bioactive Root Canal Sealer Following Root Canal Medicament Removal Using Sonic Agitation or Laser-Activated Irrigation

Objective:

To investigate the influence of sonic agitation or laser-activated irrigation techniques on the removal chlorhexidine (CHX) and modified triple antibiotic paste (mTAP) on the sealer penetration depth and dislocation resistance of Guttaflow Bioseal.

Methods:

Single-rooted mandibular premolars (n=96) were prepared with rotary nickel titanium instruments and randomly divided into two groups (n=48) based on the intracanal medicaments used: Group 1, mTAP; Group 2, CHX gel. After 7 days, the specimens in each group were divided into three subgroups (n=16) based on the supplementary irrigation technique used to remove the medicaments: laser activated irrigation (Er, Cr: YSGG laser, Waterlase MD, Biolase Technology Inc., San Clemente, CA, USA), sonic agitation (EndoActivator, Dentslpy Sirona Endodontics, PA, USA) and syringe-and-needle irrigation (control) techniques. Canals were filled with single matched-taper gutta-percha cone and a calcium silicate-based sealer (GuttaFlow® Bioseal, Coltène/Whaledent, Langenau, Germany). At the end of three weeks, sealer penetration was investigated using confocal microscopy (n=6), and dislocation resistance was calculated by measuring the push-out bond strength (n=10). Statistical analysis was performed using three-way analysis of variance (ANOVA) and Tukey post-hoc test (P=0.05).

Results:

Laser activated irrigation resulted in significantly higher depth of sealer penetration compared to sonic agitation and syringe irrigation (P<0.01). The average sealer penetration depths were recorded as 846.6 µm, 786.5 µm and 505 µm in the Er, Cr: YSGG laser, EndoActivator and control groups, respectively. The mean bond strength obtained in group 3 (syringe-and-needle irrigation) was significantly less than the other groups (P<0.05). The mean values were 9.08 in the Er, Cr: YSGG laser group, 8.44 in the EndoActivator group and 5.08 in the needle group.

Conclusion:

Er,Cr;YSGG laser irrigation to remove the medicaments was advantageous to other irrigation techniques in sealer penetration and dislocation resistance of the sealer.

Physicochemical Properties and Bioactive Potential of a New Epoxy Resin-based Root Canal Sealer

The aim of this study was to evaluate physicochemical properties and bioactive potential of Sealer Plus, in comparison with MTA Fillapex, Sealapex and AH Plus. Setting time, flow, and radiopacity were evaluated based on ISO 6876 Standard. Flow was also assessed in area (mm²). The solubility and volumetric change of the sealers were evaluated after 7 and 30 days of immersion in distilled water. Solubility was evaluated by the difference in mass of materials before and after immersion. Volumetric change was evaluated by using microcomputed tomography (micro-CT). The bioactive potential was observed by Scanning Electron Microscopy (SEM) after immersion in PBS. Data were compared using ANOVA and Tukey tests (α=0.05). Sealer Plus presented the shortest setting time (196 min.) and Sealapex the longest (912 min.) (p<0.05). AH Plus showed the highest radiopacity (9.5 mm Al) and MTA Fillapex the lowest (2.7 mm Al) (p<0.05). All the sealers presented flow in accordance with ISO 6876/2012 (>17 mm). Sealer Plus showed low solubility and volumetric change (<1%), and MTA Fillapex showed the highest solubility (>25%), and volumetric change (>4%) after all time intervals (p<0.05). MTA Fillapex was the only sealer that showed bioactive potential. In conclusion, Sealer Plus presented proper physicochemical properties. However, this sealer did not present a bioactive potential.

Solubility, Porosity, Dimensional and Volumetric Change of Endodontic Sealers

The aim of this study was to evaluate physical properties of endodontic sealers (AH Plus, MTA Fillapex and Endofill), by conventional and micro-CT tests. Dimensional stability was evaluated after immersion of materials in distilled water for 30 days. Solubility and volumetric change were evaluated after 7 and 30 days of immersion in distilled water. Solubility was evaluated by means of mass loss and volumetric change was assessed by micro-CT. Porosity was evaluated under a microscope after 7 days of immersion in distilled water, and by using micro-CT after setting and immersion in distilled water for 7 and 30 days. Statistical analysis was performed by ANOVA and Tukey's test with 5% significance level. MTA Fillapex presented the highest solubility (p<0.05), showing values above the ISO/ADA recommendations. MTA Fillapex presented higher volumetric and dimensional changes, followed by Endofill and AH Plus (p<0.05). Dimensional stability of the MTA Fillapex and AH Plus did not follow ISO/ADA standards. The highest total porosity was observed for MTA Fillapex (p<0.05). Endofill had higher total porosity than AH Plus according to microscope evaluation (p<0,05), and both sealers were similar in micro-CT assessment (p>0,05). In conclusion, MTA Fillapex presented higher solubility, dimensional and volumetric change besides porosity compared to the other evaluated sealers. The assessed physical properties of sealers are related, and the different tests provided complementary data. Micro-CT is a valuable method for assessment of physical properties of endodontic materials.

Cytotoxicity and biocompatibility of a new bioceramic endodontic sealer containing calcium hydroxide

This study evaluated the cytotoxicity and biocompatibility of a new bioceramic endodontic sealer (i.e., Sealer Plus BC) in comparison with those of MTA Fillapex and AH Plus. L929 fibroblasts were cultured and Alamar Blue was used to evaluate cell viability of diluted extracts (1:50, 1:100, and 1:200) from each sealer at 24 h. Polyethylene tubes that were filled with material or empty (as a control) were implanted in the subcutaneous tissue of rats. The rats were killed after 7 and 30 d (n = 8), and the tubes were removed for histological analysis. Parametric data was analyzed using a one-way ANOVA test, and nonparametric data was analyzed via the Kruskal-Wallis test followed by the Dunn test (p < 0.05). A reduction in cell viability was observed in the extracts that were more diluted for Sealer Plus BC when compared to that of Control and AH Plus (p < 0.05). However, the 1:50 dilution of the Sealer Plus BC was similar to that of the Control (p > 0.05). Conversely, more diluted extracts of MTA Fillapex (1:200) and AH Plus (1:100 and 1:200) were similar to the Control (p > 0.05). Histological analysis performed at 7 d did not indicate any significant difference between tissue response for all materials, and the fibrous capsule was thick (p > 0.05). At 30 d, Sealer Plus BC was similar to the Control (p > 0.05) and MTA Fillapex and AH Plus exhibited greater inflammation than the Control (p < 0.05). The fibrous capsule was thin for the Control and for most specimens of Sealer Plus BC and AH Plus. Thus, Sealer Plus BC is biocompatible when compared to MTA Fillapex and AH Plus, and it is less cytotoxic when less-diluted extracts are used.

Do in vitro solubility studies on endodontic sealers demonstrate a high level of evidence? A systematic review

OBJECTIVE

To systematically review the quality of evidence of available in vitro solubility studies on endodontic sealers according to prespecified evidence criteria.

MATERIAL AND METHODS

This systematic review was based on the PRISMA guidelines and the AMSTAR measurement tool. A systematic duplicate search of the literature on endodontic sealer solubility studies was conducted in PubMed and Embase databases (until 18 October 2017). Mapping terms to subject headings and free text terms were used and combined with hand searching before exclusion of duplicates. Studies specifically dealing with endodontic sealer solubility were selected. The evidence level was graded (low, medium or high) independently by two investigators following systematic data extraction in pilot forms, which was based on prespecified evidence criteria and the modified CONSORT checklist for in vitro studies on dental materials.

RESULTS

The search retrieved 1053 articles, from which 88 were assessed in full. From the 63 articles retained in the final analysis, 11 were classified as having moderate and 52 as low quality of evidence (0 high). The studies graded as low had low sample size (n < 10) and/or insufficient details to allow replicability. Most of the studies did not conform to the modified CONSORT checklist and did not include parameters considered relevant in the prespecified criteria.

CONCLUSIONS

Existing in vitro studies on the solubility of endodontic sealers do not demonstrate a high quality of evidence. Most of these studies do not present systematic reporting nor employ relevant parameters prespecified in our evidence criteria.

Effects of a New Bioceramic Material on Human Apical Papilla Cells

BACKGROUND

The development of materials with bioregenerative properties is critically important for vital pulp therapies and regenerative endodontic procedures. The aim of this study was to evaluate the cytocompatibility and cytotoxicity of a new endodontic biomaterial, PulpGuard, in comparison with two other biomaterials widely used in endodontic procedures, ProRoot Mineral Trioxide Aggregate (MTA) and Biodentine.

METHODS

Apical papilla cells (APCs) were isolated from third molars with incomplete rhizogenesis from patients with orthodontic indication for dental extraction. Cultured APCs were incubated for 24, 48, or 72 h with different dilutions of eluates prepared from the three materials. Cellular viability, mobility, and proliferation were assessed in vitro using the Alamar Blue assay and a wound-healing test. The cells were also cultured in direct contact with the surface of each material. These were then analyzed via Scanning Electron Microscopy (SEM), and the surface chemical composition was determined by Energy-Dispersive Spectroscopy (EDS).

RESULTS

Cells incubated in the presence of eluates extracted from ProRoot MTA and PulpGuard presented rates of viability comparable to those of control cells; in contrast, undiluted Biodentine eluates induced a significant reduction of cellular viability. The wound-healing assay revealed that eluates from ProRoot MTA and PulpGuard allowed for unhindered cellular migration and proliferation. Cellular adhesion was observed on the surface of all materials tested. Consistent with their disclosed composition, EDS analysis found high relative abundance of calcium in Biodentine and ProRoot MTA and high abundance of silicon in PulpGuard. Significant amounts of zinc and calcium were also present in PulpGuard discs. Concerning solubility, Biodentine and ProRoot MTA presented mild weight loss after eluate extraction, while PulpGuard discs showed significant water uptake.

CONCLUSIONS

PulpGuard displayed a good in vitro cytocompatibility profile and did not significantly affect the proliferation and migration rates of APCs. Cells cultured in the presence of PulpGuard eluates displayed a similar profile to those cultured with eluates from the widely used endodontic cement ProRoot MTA.

Bone tissue reaction, setting time, solubility, and pH of root repair materials

OBJECTIVES

This study aims to compare the bone tissue reaction, setting time, solubility, and pH of NeoMTA Plus, Biodentine (BD), and MTA Angelus (MTA-A).

MATERIALS AND METHODS

Initial and final setting times (n = 7) and solubility up to 7 days (n = 11) were evaluated in accordance with ASTM C266-15 and ANSI/ADA Specification No. 57, respectively. pH (n = 10) was measured up to 28 days. Bone tissue reactions in 48 rats' femur were histologically analyzed after 7, 30, and 90 days. ANOVA and Tukey's tests compared setting time, solubility, and pH data; bone reactions data were compared by Kruskal-Wallis and Dunn's tests.

RESULTS

NeoMTA Plus had longer initial and final setting times than MTA-A and BD (P < 0.05). At 7 days, BD showed the highest solubility, similar to NeoMTA Plus (P > 0.05) and different from MTA-A (P < 0.05). NeoMTA Plus had a progressive mass loss over time; at 7 days, it was significantly different from the initial mass (P < 0.05). BD showed higher pH in the periods assessed when compared to the other materials (P < 0.05). Bone tissue repair had no differences between groups in each experimental period (P > 0.05). All groups presented no difference from 30 to 90 days (P > 0.05) and had better bone repair at 90 days than at 7 days (P < 0.05).

CONCLUSIONS

NeoMTA Plus, BD, and MTA-A showed satisfactory setting time, high mass loss, alkaline pH, and allowed bone repair.

CLINICAL RELEVANCE

Calcium silicate-based cements are indicated for multiple clinical situations. NeoMTA Plus and BD showed satisfactory physical-chemical and biological properties, being considered as alternatives to MTA-A, as root repair materials for clinical use.

Chlorhexidine and proanthocyanidin enhance the long-term bond strength of resin-based endodontic sealer

The aim of this study was to evaluate the effects of proanthocyanidin (PA) and chlorhexidine (CHX) on the bond strength (BS), failure pattern, and resin-dentin interface morphology of the endodontic sealers EndoREZ and AH Plus after 24 h and 6 months of water storage. A total of 120 prepared bovine roots were divided into six groups: AH Plus, CHX+AH Plus, PA+AH Plus, EndoREZ, CHX+EndoREZ, and PA+EndoREZ. Dentin was treated for 1 or 5 min with 2% CHX or 15% PA, respectively. Roots were filled and stored in water for 24 h or 6 months (n = 10). Root slices were subjected to push-out test and scanning electron microscopy (SEM). Data were compared using two-way ANOVA and student's t-test (α = 5%). BS decreased over time for AH Plus and untreated EndoREZ (p < 0.05). At 24 h, AH Plus had higher BS than EndoREZ (p < 0.001), with no differences among treatments for both sealers (p > 0.05). At 6 months, EndoREZ had higher BS values for CHX and PA than control (p < 0.05). AH Plus had higher BS than EndoREZ (p < 0.001), while with CHX or PA, similar BS was observed in both sealers (p > 0.05). Cohesive and mixed failures were observed in all groups. SEM revealed sealer tags in the root dentin. In conclusion, BS decreased with time and AH Plus had higher BS than EndoREZ in untreated dentin; however, CHX or PA enhanced long-term BS of EndoREZ. Overall, dentin treatment affected failure pattern and resin-dentin interface morphology, particularly for EndoREZ.

Physicochemical Properties and Volumetric Change of Silicone/Bioactive Glass and Calcium Silicate-based Endodontic Sealers

INTRODUCTION

This study evaluated setting time (ST), radiopacity, pH, flow, solubility, and volumetric change (VC) of a silicone, gutta-percha, and bioactive glass-based sealer, GuttaFlow Bioseal (GFB), and a calcium silicate-based sealer, TotalFill BC Sealer (TFBC), in comparison with AH Plus.

METHODS

ST and flow were evaluated in accordance with the ISO 6876 Standard. pH was evaluated after different time intervals (1, 3, 7, 14, 21, and 28 days). Radiopacity was evaluated by radiographic analysis in millimeters of aluminum. Solubility was evaluated by means of mass loss (%) after 7 and 30 days of immersion in distilled water. VC was evaluated by micro-computed tomography, by using cavities 3 mm deep and 1 mm in diameter in acrylic resin, filled with the materials. The materials were evaluated after setting and after 7 and 30 days of immersion in distilled water. The data were submitted to analysis of variance and Tukey statistical tests (P < .05).

RESULTS

TFBC demonstrated the highest pH and solubility. GFB had the shortest ST, and lowest radiopacity and flow values. VC was similar for the sealers in both time intervals.

CONCLUSIONS

TFBC presented the highest pH and solubility, but showed similar VC to GFB and AH Plus. GFB showed proper physicochemical properties. Micro-computed tomography complements the physicochemical analysis of endodontic sealers.

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

Objective

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

Material and Methods

7.

Results

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

Conclusions

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

Solubility and pH of bioceramic root canal sealers: A comparative study

Background

This study compared the solubility and the pH of different root canal sealers in vitro.

Material and Methods

BioRoot™RCS, TotalFill BC Sealer, MTA Fillapex, SealapexTM, AH Plus, EasySeal, Pulp Canal Sealer™ and N2 were tested. Similar specimens were prepared using ring molds with an internal diameter of 20 ± 0,1 mm and a height of 1,5 ± 0,1 mm and digitally weighted to register the mass of each specimen before and after immersion in distilled water. Solubility was determined after 24 hours and statistically analysed using a one-way ANOVA test and post-hoc Tukey test. The pH value was measured by a digital pH meter after 3 and 24 hours from manipulation.

Results

BioRoot™RCS and TotalFill BC Sealer showed significantly higher solubility (P<0.05). All the remnant root canal sealers fulfilled the requirements of solubility of the International Standard Organization 6876 demonstrating a weight loss of less than 3%. BioRoot™RCS and Totalfill BC Sealer exhibited high alkaline pH over time (P<0.05); the alkalinity of the other tested cements was significantly lower.

Conclusions

The prolonged alkalinity of bioceramic sealer matched the increase in solubility. This may encourage their biological and antimicrobial effects, but the ongoing solubility may impact their ability to prevent apical leakage.

Key words:pH, root canal sealers, solubility.