Osteoinductive and regenerative potential of premixed calcium-silicate bioceramic sealers on vascular wall mesenchymal stem cells.

AIM: The osteogenic potential of new premixed calcium-silicate-containing bioceramic sealers (Ca-Si sealers) was tested with porcine vascular wall-mesenchymal stem cells (pVW-MSCs). METHODOLOGY: Two Ca-Si-containing sealers: Ceraseal (MetaBiomed, Cheong-si, South Korea) and AH Plus Bioceramic (Maruchi, Wonju-si, South Korea), and an epoxy resin sealer (AH Plus; Dentsply, Konstanz, Germany) as a control, were prepared according to the manufacturers' indications. All samples were allowed to set for 100% of their setting time in a sterile humid cabinet at 37°C and 95% relative humidity. pVW-MSC seeding efficiency and osteogenic differentiation were analysed as marker of gene/protein expression for up to 12 days. Mineralization assay and immunofluorescence staining were performed and evaluated over a period of 21 days. Statistical analyses were conducted using one-way analysis of variance (p < .05). Additional samples were prepared and stored under the same conditions and inspected using an environmental scanning electron microscope equipped with an energy dispersive X-ray spectroscopy system. RESULTS: Significantly higher cell seeding efficiency (p < .05) was observed for both Ca-Si sealers from day 8. pVW-MSCs showed a significant shift towards the osteogenic lineage only when seeded in contact with Ca-Si sealers. Gene expression of osteopontin was upregulated significantly. Collagen I and osteocalcin were clearly expressed by cells in contact with Ca-Si sealers. Mineralization granules were observed in Alizarin red assays and confocal laser scanning microscopy analysis of both Ca-Si sealers. No gene expression or granule mineralization were observed on the epoxy resin sealer. CONCLUSIONS: Premixed Ca-Si sealers displayed a higher potential for osteogenic activity on pVW-MSCs. Epoxy resin sealer was unable to induce any osteogenic activity. The properties of both Ca-Si sealers suggest their potential as osteoinductive platforms for vascular MSCs in periapical bone.

Bacterial sealing ability of calcium silicate-based sealer for endodontic surgery: an in-vitro study.

BACKGROUND: Apical surgery with standard retrograde maneuvers may be challenging in certain cases. Simplifying apical surgery to reduce operating time and streamline retrograde manipulation is an emerging need in clinical endodontics. AIM OF THE STUDY: The aim of the study was to compare the bacterial sealing ability of a calcium silicate-based sealer with the single cone technique combined with root end resection only, and calcium silicate-based sealer as a retrograde filling versus MTA retrofilling, and to analyze bacterial viability using confocal laser scanning microscope (CLSM). MATERIALS AND METHODS: In this in vitro experimental study, 50 extracted human maxillary incisor teeth were instrumented and randomly divided into five groups: three experimental groups, a positive control group, and a negative control group (n = 10/group). In the experimental groups, the roots were obturated using the single cone technique (SCT) and a calcium silicate-based sealer. In group 1, the roots were resected 3 mm from the apex with no further retrograde preparation or filling. In groups 2 and 3, the roots were resected, retroprepared, and retrofilled with either a calcium silicate-based sealer or MTA, respectively. Group 4 (positive control) was filled with a single gutta-percha cone without any sealer. In group 5 (negative control), the canals were left empty, and the roots were sealed with wax and nail varnish. A bacterial leakage model using Enterococcus faecalis was employed to assess the sealing ability over a 30-day period, checking for turbidity and analyzing colony forming units (CFUs) per milliliter. Five specimens from each group were examined using CLSM for bacterial viability. Data for the bacterial sealing ability were statistically analyzed using chi-squared and Kruskal-Wallis tests. RESULTS: The three experimental groups did not show significant differences in terms of bacterial leakage, or bacterial counts (CFUs) (P > 0.05). However, significant differences were observed when comparing the experimental groups to the positive control group. Notably, the calcium silicate-based sealer, when used as a retrofilling, yielded the best sealing ability. CLSM imaging revealed viable bacterial penetration in all the positive control group specimens while for the experimental groups, dead bacteria was the prominent feature seen. CONCLUSION: Within the limitations of this study, it could be concluded that the bacterial sealing ability of calcium silicate-based sealer with the single cone technique combined with root end resection only and calcium silicate-based sealer as a retrograde filling were comparable with MTA retrofilling during endodontic surgical procedures.

Post-operative pain in non-surgical root canal treatment after sealer-based obturation versus warm vertical compaction: A randomized clinical trial.

AIM: Post-operative pain may occur after non-surgical root canal treatment (NSRCT). The root filling technique and choice of sealer may be contributing factors. This randomized controlled clinical trial compared post-operative pain and analgesics intake after NSRCT using a sealer-based obturation technique (SBO) with single-cone gutta-percha and calcium silicate sealer (CSS) versus a warm-vertical compaction (WVC) technique with gutta-percha and a resin-based sealer (RBS). METHODOLOGY: This study was designed as a parallel-two arm, double-blind, randomized superiority clinical trial registered at www. CLINICALTRIALS: gov (NCT04753138). Patients referred for NSRCT fulfilling the inclusion criteria participated in this study. Pre-operative periapical radiographs and CBCT scans were taken and numerical rating scale (NRS) pain scores were recorded. Upon completion of canal instrumentation, participants were randomly allocated to either Group SBO: SBO with CSS or Group WVC: Warm-vertical compaction with RBS. Post-operative pain and analgesics intake were recorded at 1, 3 and 7 days after endodontic treatment completion. Non-parametric Mann-Whitney U and Friedman tests and a generalized estimating equation were used to assess differences in pain scores between the groups, within each treatment group at different time points and for correlations, respectively. RESULTS: The study included 195 participants (212 teeth). One participant declined to submit the NRS form. Therefore, 194 participants (211 teeth) were included in the final analysis (99.5% response rate). No statistically significant differences in post-operative pain or analgesic intake existed between the two groups at any time point (p > .05). Age, pre-operative pain, apical diagnosis and post-operative analgesic intake were significantly related to post-operative pain (p < .05). CONCLUSIONS: Sealer-based obturation technique with CSS was associated with similar post-operative pain levels and analgesics intake as WVC with RBS. Regarding post-operative pain, SBO with CSSs may be a suitable clinical alternative.

Effect of heat application on the physicochemical properties of new endodontic sealers: an in vitro and SEM study.

Understanding the properties of endodontic sealers is vital for treatment planning. Calcium silicate-based sealers are important in modern endodontics. This study investigates the effect of heat on the physicochemical properties of new calcium silicate sealers, addressing concerns raised by clinicians seeking to combine their benefits with the gutta-percha obturation technique. Five endodontic sealers (AH Plus Bioceramic®, Total Fill® BC®, One-fil® Bioceramic, K-Biocer, Any-seal®) were evaluated. Each sealer (n = 16/group) was either kept at 37 °C or subjected to heat at 60 or 200 °C for 30 s. ISO 6876-2012 standards were used to measure setting time, flow, film thickness, and dimensional changes over time. SEM and EDS were utilized for surface and chemical analysis. Data analysis employed IBM SPSS Statistics version 26 with a 5% significance level for two-sided tests. The sealers' setting times were shortened by heat, except for Total Fill® BC with extended setting time. All sealers had significantly longer setting times than manufacturer specifications. Film thickness increased with temperature, while flow values decreased. K-Biocer sealer showed the highest flow (16.89 ± 0.57 mm) at 200 °C, while Total Fill® sealer had the lowest (15.32 ± 0.62 mm). Shrinkage was significant at 60 °C and 200 °C, with greater shrinkage at 200 °C. Heat caused surface deformations in all sealers. The 200 °C groups exhibited more voids in AH Plus Bioceramic®, Any-seal®, and One-fil® sealers, and higher void area in Total Fill®, One-fil®, and K-Biocer sealers (p value < 0.001). EDX analysis confirmed heat-induced chemical and elemental changes in all tested sealers. Elevated temperature affects the physicochemical properties and structure of the tested endodontic sealers. The consideration of endodontic sealer compatibility is essential when warm gutta-percha obturation techniques are used.

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

BACKGROUND: The aim of this study was to evaluate the effect of thermal and mechanical cyclic aging using a mastication simulator on push-out bond strength of mandibular premolars obturated with AH Plus and BioRoot RCS root canal sealers. METHODS: With REVO-S files up to SU/0.06 taper, 48 single-rooted premolar teeth were instrumented. The teeth were randomly divided into two main groups (n = 24) based on the two root canal sealers used (AH Plus and BioRoot RCS). All teeth were obturated with h matched-taper single-cone. Each main group was then subdivided into three subgroups (A, B, and C) (n = 8). Group A served as the negative control group (no-thermocycling aging). While groups B and C were subjected to thermal changes in a thermocycler machine (15,000 and 30,000 thermal cycles, respectively), followed by two different dynamic loading periods, 3 × 105 and 6 × 105 in a masticatory simulator with a nominal load of 5 kg at 1.2 Hz which represent roughly 1½ and 3 years of clinical function respectively. 2 mm slice at 3 levels, apical, middle, and coronal, to obtain 3 sections were prepared and subjected to push-out test using a universal testing machine. Statistical analysis was performed using analysis of variance (ANOVA) followed by a Tukey post hoc comparisons test and an independent T-test. A significance level of 5% was used. RESULTS: After thermal-mechanical cyclic aging, the two root canal sealers showed a significantly decreased in push-out bond strength (p < 0.05), however, AH Plus had significantly higher bond strength values than BioRoot RCS after cycling aging. CONCLUSIONS: It could be concluded that thermal-mechanical cyclic aging had a significant impact on the outcome of the dislodgment resistance of AH Plus and BioRoot RCS.

Efficacy of Shock Wave-Enhanced Emission Photoacoustic Streaming (SWEEPS) in the Removal of Different Combinations of Sealers Used with Two Obturation Techniques: A Micro-CT Study.

This study sought to evaluate the efficacy of SWEEPS in the removal of epoxy-resin-based and calcium-silicate-containing endodontic sealer combined with single-cone and carrier-based obturation techniques through a micro-CT analysis. Seventy-six single-rooted extracted human teeth with single root canal were instrumented with Reciproc instruments. Specimens were randomly divided into four groups (n = 19) according to the root canal filling material and obturation technique: (1) AH Plus sealer + Reciproc gutta-percha, (2) TotalFill BC sealer + TotalFill BC Points, (3) AH Plus sealer + Guttafusion obturator, and (4) MTA Fillapex + Guttafusion obturator. All specimens were re-treated one week later using Reciproc instruments. Following re-treatment, root canals were additionally irrigated using the Auto SWEEPS modality. The differences in the root canal filling remnants were analyzed by micro-CT scanning of each tooth after root canal obturation, after re-treatment, and after additional SWEEPS treatment. Statistical analysis was performed using an analysis of variance (p < 0.05). The additional treatment with SWEEPS significantly reduced the volume of the root canal filling materials in all experimental groups compared to the removal of root canal filling using only reciprocating instruments (p < 0.05). However, the root canal filling was not removed completely from any of the samples. SWEEPS can be used to enhance the removal of both epoxy-resin-based and calcium-silicate-containing sealers, in combination with single-cone and carrier-based obturation techniques.

Inflammatory response to epoxy resin and calcium silicate sealers preheated with different temperatures: an in vivo study.

OBJECTIVE: To determine the impact of heat exposure of different sealers on inflammatory cytokine secretions and tissue response in vivo. MATERIALS AND METHODS: Silicone tubes were prefilled with epoxy resin (ER) or calcium silicate (CS) sealers, preheated at 37, 60, or 120 °C, and implanted in rat subcutaneous site. Peri-implant exudate and tissue were analyzed after 1 and 4 weeks for cytokine secretions and tissue organization. RESULTS: At 1 week, 120 °C-preheated CS and ER induced higher secretions of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6), respectively, as compared to sham/empty tube groups. At 4 weeks, whereas TNF-α secretion was reduced in CS, it increased in ER group, particularly for 120 °C. Both sealers revealed high IL-6 after 4 weeks as compared to sham/empty tube, and generally, higher IL-6 secretions were associated with ER. Histology at 1 week revealed lower degree of inflammatory infiltrate in the groups of the highest preheating temperature (120 °C). Nonetheless, at 4 weeks, whereas fibrous capsule area and inflammatory infiltrate remained low in the CS120 group, they were high in ER120. CONCLUSION: Preheating ER sealer to 120 °C induced high and prolonged secretion of proinflammatory cytokines (TNF-α and IL-6), whereas this effect was transient for the CS sealer. This was associated with increased fibrous capsule and inflammatory infiltrate in response to 120 °C-preheated ER. CLINICAL RELEVANCE: Heat-induced changes in sealer properties alter the inflammatory response in vivo, which may affect the clinical outcome. This will not only help appropriate selection of obturation technique for different sealers, but also for optimizing the properties of new generation of sealers.

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

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

Premixed Calcium Silicate-Based Root Canal Sealer Reinforced with Bioactive Glass Nanoparticles to Improve Biological Properties.

Recently, bioactive glass nanoparticles (BGns) have been acknowledged for their ability to promote interactions with the periapical tissue and enhance tissue regeneration by releasing therapeutic ions. However, there have been no studies on calcium silicate sealers with bioactive glass nanoparticle (BGn) additives. In the present study, a premixed calcium silicate root canal sealer reinforced with BGn (pre-mixed-RCS@BGn) was developed and its physicochemical features and biological effects were analyzed. Three specimens were in the trial: 0%, 0.5%, and 1% bioactive glass nanoparticles (BGns) were gradually added to the premixed type of calcium silicate-based sealer (pre-mixed-RCS). To elucidate the surface properties, scanning electron microscopy, X-ray diffraction, and energy-dispersive spectroscopy were used and flowability, setting time, solubility, and radiopacity were analyzed to evaluate the physical properties. Chemical properties were investigated by water contact angle, pH change, and ion release measurements. The antibacterial effects of the bioactive set sealers were tested with Enterococcus faecalis and the viability of human bone marrow-derived mesenchymal stem cells (hMSCs) with this biomaterial was examined. In addition, osteogenic differentiation was highly stimulated, which was confirmed by ALP (Alkaline phosphatase) activity and the ARS (Alizarin red S) staining of hMSCs. The pre-mixed-RCS@BGn satisfied the ISO standards for root canal sealers and maintained antimicrobial activity. Moreover, pre-mixed-RCS@BGn with more BGns turned out to have less cytotoxicity than pre-mixed-RCS without BGns while promoting osteogenic differentiation, mainly due to calcium and silicon ion release. Our results suggest that BGns enhance the biological properties of this calcium silicate-based sealer and that the newly introduced pre-mixed-RCS@BGn has the capability to be applied in dental procedures as a root canal sealer. Further studies focusing more on the biocompatibility of pre-mixed-RCS@BGn should be performed to investigate in vivo systems, including pulp tissue.

Effect of Different Irrigation Solutions on the Diffusion of MTA Cement into the Root Canal Dentin.

(1) Aim: This study aims to analyze the in vitro infiltration of a silicate root canal sealer into dentinal tubules after using different endodontic irrigating solutions. (2) Methods: Twenty-nine teeth with single roots were separated into three groups according to the final irrigation protocol: G1 n = 10) = 17% EDTA (ethylenediaminetetraacetic acid) + 3.0% sodium hypochlorite (NaOCl), G2 (n = 10) = 17% EDTA + 2.0% chlorhexidine and G3 (Control group, n = 9) = 17% EDTA + saline solution. Root canals were filled using cold lateral compaction technique with MTA Fillapex sealer and gutta-percha. The sealer was labeled with rhodamine B. The teeth were segmented at the middle and third apical sections, which were visualized using 10× confocal laser microscopy to determine the sealer penetration percentage. (3) Results: In the apical section, no statistically significant differences were found between the groups regarding sealer penetration. In the middle section, Group 1 obtained the highest percentage, and Group 2 the lowest (p = 0.004). Group 1 also presented statistically significant differences in the Control Group (p = 0.031) and had close sealer penetration values. Meanwhile, the Control Group (p = 0.023) and Group 2 (p = 0.029) revealed a significant decrease of sealer penetration between the apical and middle sections. (4) Conclusion: The obtained results support that final irrigation with NaOCl promoted similar sealer penetration in the apical and middle sections. On the other hand, a significant decrease in the sealer penetration of the middle section was observed for the chlorhexidine and saline groups. Compared to other irrigant solutions, NaOCl promotes more uniform sealer penetration, which can correlate with better sealing and, consequently, higher endodontic treatment success.

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 fracture resistance of roots-filled with various root canal sealers at different time periods.

PURPOSE: The reinforcement effect of 3 various root canal sealers (AH 26, MTA Plus sealer and BioRoot RCS) and gutta-percha at different time periods (1 week and 1 month) were evaluated in the present study. MATERIALS AND METHODS: Single-rooted, single-canalled, cracks-free 80 mandibular premolars were decoronated to a length of 13mm. Group PC (positive control, n=10): samples were left unprepared and unfilled. Seventy samples were prepared by using the ProTaper Rotary System up to F4. Group NC (negative control, n=10): samples were left unfilled. Remaining 60 samples were assigned into 3 groups; Group 1: AH 26 + F4 gutta-percha (GP); Group 2: MTA Plus sealer + F4 GP and Group 3: BioRoot RCS + F4 GP. Filled samples were divided into subgroups according to storage time: Samples in Groups 1A, 2A, and 3A were stored for 1 week; while Groups 1B, 2B and 3B were stored for 1 month at 100% humidity to allow the complete setting of the sealers (n=10, for each). A universal testing machine at a crosshead speed of 1.0 mm/min was used for fracture testing. For each specimen, the force at the time of fracture was recorded and the data were analyzed statistically. RESULTS: The highest fracture resistance values were obtained in Group PC, while the lowest values were obtained in Group NC. Groups PC and NC were statistically different from each other and from other groups, regardless of time (p<0.05). Fracture resistance values of Group AH 26/GP were statistically different from MTA Plus sealer/GP (p<0.05) and were statistically similar with BioRoot RCS/GP , irrespective of time. Within group comparisons revealed that there were no statistically differences between samples filled with same sealer at different time periods. CONCLUSION: Root canal preparation caused decreased fracture resistance. All sealers increased the force values needed to fracture the filled samples compared to unfilled ones. Time factor had no effect on the fracture resistance values.

The Penetration Ability of Calcium Silicate Root Canal Sealers into Dentinal Tubules Compared to Conventional Resin-Based Sealer: A Confocal Laser Scanning Microscopy Study.

The purpose of this study was to compare the penetration ability of calcium silicate root canal sealers and conventional resin-based sealer using confocal laser scanning microscopy (CLSM). A total of 60 recently extracted single-rooted human premolars were used in this study. The root canals were prepared to a size 40/0.06 taper with ProFile rotary instruments and irrigated with NaOCl and EDTA. After drying all canals, the specimens were randomly divided into three experimental groups (n = 20): Group 1, gutta-percha (GP)/AH Plus with continuous wave compaction; group 2, GP/BioRoot RCS with a single-cone technique; and group 3, GP/Endoseal MTA with a single-cone technique. All experimental samples were sectioned perpendicular to their long axis using a low-speed diamond wheel at the apical, middle, and coronal third levels. The penetration abilities of all samples were evaluated using CLSM. A Kruskal⁻Wallis analysis and a series of Mann⁻Whitney U post hoc tests were performed. A higher intensity level was found in the coronal area and a lower intensity level in the apical area in all the experimental groups. The AH Plus group showed higher sum fluorescence intensity in the apical and coronal thirds compared with the BioRoot RCS and Endoseal MTA groups, whereas the BioRoot RCS group showed a higher intensity level in the middle third, similar to the AH Plus group. The maximum sealer penetration depth was low in the apical area and high in the coronal area in the AH Plus and Endoseal MTA groups. In the BioRoot RCS group, maximum sealer penetration was observed in the middle third. In conclusion, there were significant differences in sealer penetration pattern and distance according to the root level and sealer type.

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

INTRODUCTION: A root canal obturated with a calcium silicate-based sealer (bioceramic sealer [BCS]) and a modified gutta-percha cone (bioceramic cone [BCC]) might improve the fracture resistance of the root. The objective of this study was to evaluate root reinforcement of a bioceramic cone/sealer (TotalFill; FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) by investigating the fracture resistance, push-out bond strength, sealer penetration, and modulus of elasticity (MOE) in comparison with gutta-percha/AH Plus (Dentsply Maillefer, Tulsa, OK) (GP/AH). METHODS: Eighty-four roots from bilateral mandibular premolars were prepared. For fracture resistance, 40 teeth were randomly divided into 4 groups (n = 10 each): intact roots (negative control), prepared roots (positive control), and the roots obturated with either BCC/BCS or GP/AH. Root canals were obturated with the matched single-cone technique and vertically loaded with a spreaderlike tip until fracture. For push-out bond strength (n = 10 each), coronal, middle, and apical root slices of BCC/BCS and GP/AH were loaded with a cylindrical plunger, and failure modes were determined. Sealer penetration of BCC/BCS and GP/AH (n = 12 each) was evaluated for the maximum depth and the circumferential and total area of penetration at the coronal, middle, and apical levels using confocal laser scanning microscopy. The MOE was investigated according to ISO 4049:2000. RESULTS: The fracture load of BCC/BCS, GP/AH, and the intact roots was not significantly different but significantly higher than the prepared, nonobturated roots. BCC/BCS provided a higher bond strength, maximum depth, and circumferential penetration at the apical root level as well as a greater sealer penetration area at all levels compared with GP/AH. The MOE of all materials was much lower than dentin. CONCLUSIONS: BCC/BCS and GP/AH bonded and reinforced the prepared roots; their fracture resistances were similar to the intact roots.

Synchrotron-based Phase Contrast-enhanced Micro-Computed Tomography Reveals Delaminations and Material Tearing in Water-expandable Root Fillings Ex Vivo.

INTRODUCTION: This study evaluated the integrity of calcium silicate sealer-based fillings made with hygro-expandable cones (HEC) that are commercially known as CPoint or Smartpoint. METHODS: Fourteen human canines were prepared according to a standardized, conventional endodontic treatment protocol and filled with the HEC/calcium silicate sealer. Three-dimensional imaging was performed with laboratory micro-computed tomography (µCT) at its highest resolution and was compared with synchrotron phase contrast-enhanced µCT (PCE-CT) scans of the treatment extending 1-7 mm from the apex. Conventional destructive optical microscopy validated observations by comparison with virtual slices in the tomographic data. RESULTS: Conventional laboratory µCT at 10-µm resolution did not reveal the existing voids and defects within the root canal fillings. PCE-CT revealed elongated interfacial delamination localized mainly at the HEC-sealer interface forming extended through-and-through gaps along the root canal filling. CONCLUSIONS: Endodontic studies that use conventional laboratory µCT may underestimate thin defects and delamination within root canal fillings made with HEC because of limited resolution and contrast of laboratory-based broad-spectrum low intensity x-ray sources. These limitations favor use of high-brilliance, monochromatic synchrotron-based PCE-CT to reveal the important micrometer details within large (millimeter sized) samples. PCE-CT revealed the existence of a range of significant structural defects in recently placed HEC fillings, confirmed by optical microscopy after physical sectioning. Substantial delamination spanning 20%-40% of the circumferential interface as well as other structural defects were identified within root canal fillings made of HEC and calcium silicate sealer.