Microscopic appearance and apical seal of root canals filled with gutta-percha and ProRoot Endo Sealer after immersion in a phosphate-containing fluid

Biological properties versus solubility of endodontic sealers and cements

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

Comparative evaluation of dentinal tubule penetration and push-out bond strength of new injectable hydraulic calcium disilicate based root canal sealer: A single blinded in vitro study

Objective

To evaluate and compare dentinal tubule penetration and push-out bond strength of BIO-C ION+, AH Plus and NanoSeal-S using Confocal Laser Scanning Microscopy (CLSM) and Universal Testing Machine (UTM).

Materials & method

Sixty human mandibular premolars were prepared using ProTaper Gold till F3. Samples were then divided into 3 groups: Group I (n = 20) BIO-C ION + sealer, Group II (n = 20) AH Plus and Group III (n = 20) NanoSeal-S sealer. Groups were then sub-divided into two sub groups: In Subgroup A (n = 10) samples were obturated using single-cone with 0.1 % Rhodamine B dye and in Subgroup B (n = 10) samples were obturated using single cone. The samples were then transversely sectioned into coronal, middle and apical segments, samples in subgroup A & B were then submitted to CLSM analysis and UTM respectively.

Results

The Bond Strength data showed following means (MPa): Group I Subgroup B: (BIO-C ION+) coronal (1.64), middle (1.25), apical (0.93); Group II Subgroup B: (AH Plus) coronal (2.20), middle (1.85) apical (1.38) and Group III Subgroup B: (NanoSeal-S) coronal (1.26), middle (0.94), apical (0.58). The dentinal tubule penetration data showed following means: (μm) Group I Subgroup A (BIO-C ION+) coronal (1184.69), middle (997.03), apical (637.26); Group II Subgroup-A AH Plus (864.14) and NanoSeal-S (495.64). Statistical analysis (two-way ANOVA, Tukey's Post Hoc Test) showed significant difference among sealers (p < 0.001) and root canal thirds (p < 0.001).

Conclusion

The results of the study concluded that BIO-C ION + sealer showed maximum dentinal tubule penetration and AH Plus demonstrated maximum push-out bond strength.

A scientometric, bibliometric, and thematic map analysis of hydraulic calcium silicate root canal sealers

Objectives

This scientometric and bibliometric analysis explored scientific publications related to hydraulic calcium silicate-based (HCSB) sealers used in endodontology, aiming to describe basic bibliometric indicators and analyze current research trends.

Materials and Methods

A comprehensive search was conducted in Web of Science and Scopus using specific HCSB sealer and general endodontic-related terms. Basic research parameters were collected, including publication year, authorship, countries, institutions, journals, level of evidence, study design and topic of interest, title terms, author keywords, citation counts, and density.

Results

In total, 498 articles published in 136 journals were retrieved for the period 2008-2023. Brazil was the leading country, and the universities of Bologna in Italy and Sao Paolo in Brazil were represented equally as leading institutions. The most frequently occurring keywords were "calcium silicate," "root canal sealer MTA-Fillapex," and "biocompatibility," while title terms such as "calcium," "sealers," "root," "canal," "silicate based," and "endodontic" occurred most often. According to the thematic map analysis, "solubility" appeared as a basic theme of concentrated research interest, and "single-cone technique" was identified as an emerging, inadequately developed theme. The co-occurrence analysis revealed 4 major clusters centered on sealers' biological and physicochemical properties, obturation techniques, retreatability, and adhesion.

Conclusions

This analysis presents bibliographic features and outlines changing trends in HCSB sealer research. The research output is dominated by basic science articles scrutinizing the biological and specific physicochemical properties of commonly used HCSB sealers. Future research needs to be guided by studies with a high level of evidence that utilize innovative, sophisticated technologies.

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.

Acid neutralizing and remineralizing orthodontic adhesive containing hydrated calcium silicate

OBJECTIVES

The objective of this study was to evaluate an orthodontic adhesive containing hydrated calcium silicate (hCS) in terms of its bond strength with the enamel surface and its acid-neutralization and apatite-forming abilities.

METHODS

The experimental orthodontic adhesives were composed of 30 wt.% resin matrix and 70 wt.% filler, which itself was a mixture of silanized glass filler and hCS in weight ratios of 100% glass filler (hCS 0), 17.5% hCS (hCS 17.5), 35% hCS (hCS 35.0), and 52.5% hCS (hCS 52.5). The degree of conversion (DC) and shear bond strength (SBS) of bovine enamel surfaces were tested. pH measurements were performed immediately upon submersion of the specimens in a lactic acid solution. The surface precipitates that formed on specimens immersed in phosphate-buffered saline (PBS) were analyzed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and Raman spectroscopy after 15, 30, and 90 days.

RESULTS

The experimental groups exhibited no significant differences in DC and had clinically acceptable SBS values. The hCS-containing groups showed increasing pH values as more hCS was added. hCS 52.5 produced Ca- and P-containing surface precipitates after PBS immersion, and hydroxyapatite deposition was detected after 15, 30, and 90 days.

CONCLUSIONS

These results suggest that orthodontic adhesives containing hCS are effective for acid neutralization. Furthermore, hCS has an apatite-forming ability for enamel remineralization.

CLINICAL SIGNIFICANCE

The novel orthodontic adhesive containing hCS exhibits a potential clinical benefit against demineralization and enhanced remineralization of the enamel surface around or beneath the orthodontic brackets.

Medium- and Long-Term Re-Treatment of Root Canals Filled with a Calcium Silicate-Based Sealer: An Experimental Ex Vivo Study

This study investigated the possibility of re-treating a calcium silicate-based sealer (CSBS), compared to an epoxy-resin sealer (RBS), using rotary instrumentation at different times from obturation (1 month/1 year). Thirty-six human mandibular premolars, extracted as a result of orthodontic or periodontal problems, were instrumented and randomly divided into three groups of 12: BR and BR*, which were filled with CSBS and re-treated after one month and one year of storage, respectively, and AH, which was filled with RBS and re-treated after one month. The same re-treatment protocol was used for all teeth, and the times required for the procedure was recorded. The re-treated specimens were longitudinally sectioned and examined at the stereomicroscope (SM) at 20× magnification. Image J Software was used to process the microphotographs. The percentage of residual filling materials in the root canal and the apical third, the ability to reach working length WL and patency, and the time taken to complete the re-treatment were recorded and analyzed by ANOVA and post hoc Bonferroni test (p = 0.05). Scanning electron microscopy (SEM) and coupled energy-dispersive spectroscopy (EDS) were applied to representative samples to evaluate canal cleanliness and chemical elements. Patency and WL were re-established in all of the teeth. Residual filling materials were retained in all specimens of the three groups. The mean percentage of residual materials was significantly different between BR and BR* (p-value = 0.048), with BR* showing the highest values. The mean time to complete re-treatment was significantly lower for AH, followed by BR (p = 0.0001) and BR* (p = 0.0078). Conclusions: After both medium and long storage periods, the CSBS can be concluded to have been successfully removed from canals with simple anatomy.

The Retrievability of Calcium Silicate-Based Sealer during Retreatment and the Effectiveness of Additional Passive Ultrasonic Irrigation: A Microcomputed Tomographic Study

This study investigated the retreatability of EndoSeal MTA (Maruch, Wonju, Korea) according to the presence or absence of a canal isthmus and the additional use of passive ultrasonic irrigation (PUI) through microcomputed tomography (micro-CT) imaging. An epoxy resin sealer (AH Plus (Dentsply DeTrey, Konstanz, Germany)) was used as a reference for comparison. Forty-five artificial mandibular molars (TRUETOOTH #19, DELABS, Santa Barbara, CA) with a mesial canal with an isthmus and a distal canal without an isthmus were obturated using gutta-percha and one of the following sealers (n = 15 each): AH Plus, EndoSeal MTA, and EndoSeal MTA + PUI. Micro-CT scanning was performed to assess the void volume (as a percentage) at three root levels. After the root fillings were removed, second micro-CT scanning was conducted to evaluate the amount of remaining root filling material. The Kruskal-Wallis H test and post hoc analysis were used for between-group comparisons. The Mann-Whitney U test was used for comparisons between canals with and without an isthmus (p < 0.05). In the EndoSeal MTA group, the void volume and remaining filling materials were higher irrespective of the presence or absence of an isthmus. In apical lesions in the EndoSeal MTA group, the void ratio was significantly lower, and there was a significantly higher amount of remaining filling material. Regardless of the presence of an isthmus, the amount of remaining filling material of the EndoSeal + PUI group was reduced to a similar degree as the AH plus group. When performing retreatment for root canals filled with EndoSeal MTA, removal of the filling material can be more difficult in the apical region. The additional use of PUI can improve the efficacy of removal.

Calcium silicate-based root canal sealers: a literature review

Epoxy resin-based sealers are currently widely used, and several studies have considered AH Plus to be the gold-standard sealer. However, it still has limitations, including possible mutagenicity, cytotoxicity, inflammatory response, and hydrophobicity. Drawing upon the advantages of mineral trioxide aggregate, calcium silicate-based sealers were introduced with high levels of biocompatibility and hydrophilicity. Because of the hydrophilic environment in root canals, water resorption and solubility of root canal sealers are important factors contributing to their stability. Sealers displaying lower microleakage and stronger push-out bond strength are also needed to endure the dynamic tooth environment. Although the physical properties of calcium silicate-based sealers meet International Organization for Standardization recommendations, and they have consistently reported to be biocompatible, they have not overcome conventional resin-based sealers in actual practice. Therefore, further studies aiming to improve the physical properties of calcium silicate-based sealers are needed.

Chemico-physical and mechanical evaluation of three calcium silicate-based pulp capping materials

Aim

This study compared biointeractivity (pH of soaking water and calcium ions), porosity, water sorption, solubility, compressive strength, lap shear strength, as well as the apatite forming ability of three calcium silicate-based capping materials: Mineral trioxide aggregate (MTA), Biodentine (BD) and Tech Biosealer capping (BS).

Methods

One hundred and five discs of the tested materials were prepared in compliance with the manufacturer's instructions. The materials' pastes were placed in Teflon molds and allowed to set before testing. The pH and Ca⁺² ions were measured by a potentiometric method. Porosity, water sorption, and solubility were calculated through the measurement of initial mass, mass, saturated mass and dry mass. Apatite forming ability was measured by an Environmental Scanning Electron Microscope that was connected to a secondary electron detector for energy dispersive X-ray analysis. Meanwhile compressive strength was measured by a computer controlled universal testing machine. Lap shear strength was measured by computer software on the testing machine. All data were statistically analyzed.

Results

The tested materials showed Ca ions release and alkalization, which decreased with soaking time. The BD exhibited a very high Ca release at both short (3 h) and long times (28 days). Significant high values of open and apparent porosities, water sorption, and solubility were measured for BS, which was followed by the MTA then BD (P < .05). The BD had significant higher compressive and lap shear bond strength than the MTA and BS (P < .05).

Conclusion

MTA, BD and BS are biointeractive bioactive materials that possess the ability to release ions and form calcium phosphate deposits. Unlike BD, BS is incapable of alternating MTA in pulp capping due to its high porosities, water sorption and solubility, as well as poor compressive and lap shear bond strength.

Bioactive tri/dicalcium silicate cements for treatment of pulpal and periapical tissues

Over 2500 articles and 200 reviews have been published on the bioactive tri/dicalcium silicate dental materials. The indications have expanded since their introduction in the 1990s from endodontic restorative and pulpal treatments to endodontic sealing and obturation. Bioactive ceramics, based on tri/dicalcium silicate cements, are now an indispensable part of the contemporary dental armamentarium for specialists including endodontists, pediatric dentists, oral surgeons andfor general dentists. This review emphasizes research on how these materials have conformed to international standards for dental materials ranging from biocompatibility (ISO 7405) to conformance as root canal sealers (ISO 6876). Potential future developments of alternative hydraulic materials were included. This review provides accurate materials science information on these important materials. STATEMENT OF SIGNIFICANCE: The broadening indications and the proliferation of tri/dicalcium silicate-based products make this relatively new dental material important for all dentists and biomaterials scientists. Presenting the variations in compositions, properties, indications and clinical performance enable clinicians to choose the material most suitable for their cases. Researchers may expand their bioactive investigations to further validate and improve materials and outcomes.

The efficacy of different irrigation protocols in removing tricalcium silicate-based sealers from simulated root canal irregularities

OBJECTIVE

The aim of this study was to evaluate the efficacy of different irrigation protocols in removing two tricalcium silicate-based sealers from simulated root canal irregularities and root canal walls.

MATERIAL AND METHODS

Root canals of 140 single-rooted teeth were instrumented. In one-half of each root, an apical groove was created. The samples were divided into two main groups (n = 70) based on the sealer used. In group 1, the grooves were filled with MTA Fillapex; in group 2, BioRoot RCS. The reassembled root halves were divided into six experimental and one control groups: 2.5% NaOCl-17% EDTA (Passive ultrasonic irrigation [PUI]), 5% NaOCl/9% DualRinse HEDP (PUI), 2.5% NaOCl-7% Maleic acid (PUI), 2.5% NaOCl-17% EDTA (Er:YAG laser activated irrigation [LAI]), 2.5% NaOCl/9% DualRinse HEDP (LAI), 2.5% NaOCl-7% Maleic acid (LAI), Distilled water (Control). Specimens were scored using SEM. The data were analysed using Kruskal-Wallis and Mann Whitney U tests.

RESULTS

Maleic acid and DualRinse HEDP removed higher amounts of MTA Fillapex from the grooves compared to EDTA, when used with both activation methods (p < .001).

CONCLUSIONS

Ultrasonically activated maleic acid or DualRinse HEDP can be an effective irrigation regimen in removing tricalcium silicate-based sealers.

Novel Calcium Zirconate Silicate Cement Biomineralize and Seal Root Canals

This study evaluated the sealing ability of gutta-percha (GP) with a calcium silicate-based sealer and a novel calcium zirconate containing calcium silicate cement (ZC). The root canals of the extracted premolars were prepared, which were then randomly allocated to three experimental groups (12 root canals per group) for obturation by continuous wave of condensation with the GP and AH 26 sealer (CW); obturation using a single GP with a calcium silicate-based EndoSequence BC sealer (SC); or obturation with ZC. The roots were inserted into sterile Eppendorf tubes, which were inoculated coronally with Porphyromonas gingivalis. The amount of endotoxin leakage into the apical reservoirs were measured using the Limulus Amebocyte Lysate (LAL) assay over 21 days, with comparisons made using one-way ANOVA and Scheffe’s tests (α = 0.05). After 21 days, 75% of the canals that had been obturated by SC, 50% of those obturated by CW and 42% of those obturated by ZC showed endotoxin leakage. The amount of leakage was higher in the SC canals than in the CW (p = 0.031) or ZC (p = 0.03) canals, although there was no significant difference in the amount of leakage for CW and ZC (p > 0.05). X-ray diffraction revealed the presence of tricalcium silicate (Ca₃SiO₅) and calcium zirconate (CaZrO₃) in the synthesized ZC. Scanning electron microscopy revealed mineralized precipitates on the dentin of canals obturated by ZC. The novel calcium zirconate silicate cement appears to promote biomineralization and seal root canals at least as effectively as the conventional sealer.

Classification and Nomenclature of Commercial Hygroscopic Dental Cements

Objective

Under the Global Medical Device Nomenclature (GMDN) system, the newly introduced term 'hygroscopic dental cement' (HDC) encompasses MTA as well as cements based on bioceramics, calcium silicate or calcium sulphate. Many HDCs have a long history of use in dentistry. There is a need for a consistent, logical and informed approach to the nomenclature of traditional and novel HDCs.

Methods

Commercial manufacturers of HDC were contacted requesting information on the compositions of products. Manufacturers that were unknown to the authors, that were unable to be contacted, that wished to be excluded from this paper, or that did not send their information on compositions in due time were not included.

Results

The compositions of commercial HDCs include various hybrids of calcium silicates, calcium aluminates, calcium phosphates, calcium sulphate as well as zinc sulphates. Furthermore, there are variations in the radiopacifier as well as additives that change the handling or setting processes.

Conclusion

The inclusion of different additives to HDCs enables variation in handling properties such that they now exist as distinct putties and sealers as well as cements.

Stereomicroscopic Dye Leakage Measurement of Six Different Root Canal Sealers

INTRODUCTION

Hermetic sealing of the root canal is the most desirable outcome of any root canal treatment, but almost always the filling of the root canal is defective, which is a multifactorial outcome. One such factor majorly influencing the obturation is the root canal sealer used.

AIM

The present study was done for evaluating microleakage in different root canal sealers.

MATERIALS AND METHODS

Sixty extracted human single rooted teeeth were used in this in-vitro study. Sealers tested for microleakage in this study were zinc oxide eugenol based sealer, Sealapex, AH Plus, MTA Plus, EndoRez, Endosequence BC. All the specimens were examined under stereomicroscope for microleakage and the obtained data were statistically analysed using One-way ANOVA test and Tukey's multiple comparision tests using the software GraphPad Prism 7.02.

RESULTS

The Endosequence BC group showed the least dye leakage and the highest leakage was seen in Zinc oxide Eugenol based sealer.

CONCLUSION

Bio ceramic salers being hydrophilic show better sealing ability compared to resin based and eugenol based sealers.

An Invitro Evaluation of Antimicrobial Efficacy and Flow Characteristics for AH Plus, MTA Fillapex, CRCS and Gutta Flow 2 Root Canal Sealer

INTRODUCTION

Cleaning and shaping of root canal does not guarantee complete disinfection of the canal, regardless of the systems and techniques used for this purpose. Therefore, it becomes mandatory for the endodontic filling materials to have a good antimicrobial potential especially against E. faecalis. This research was aimed therefore to evaluate the antibacterial efficacy and flow properties of different root canal sealers.

AIM

To study invitro antimicrobial activity and flow characteristics for Resin based (AH Plus), Mineral Trioxide Aggregate based (MTA Fillapex), Calcium hydroxide based (CRCS) and Flowable Gutta-Percha (Gutta Flow 2) endodontic sealers on Enterococcus faecalis.

MATERIALS AND METHODS

Enterococcus faecalis ATCC 29212 was used to test antibacterial potential of sealers by Agar diffusion test (ADT) and Direct Contact Test (DCT). ADT was performed by punching the sealers on a well of 4×6mm diameter on Muller Hinton agar plates. These plates were inoculated with standard suspension of E. faecalis and the zone of inhibition was measured at 24 hours and after 7 days. All the sealers were prepared in accordance with the manufacturer's recommendations. Flow of sealers was measured according to ADA specification no. 57.

RESULTS

All sealers showed antibacterial activity against E. faecalis except Gutta Flow 2. At 24 hours, zone of inhibition was highest in Calcibiotic Root Canal Sealer (CRCS) and lowest in AH Plus. After 7 days the zone of inhibition decreased in AH plus, CRCS and MTA Fillapex. DCT showed a significant lower number of organisms in AH Plus, CRCS and MTA than controls at both the time intervals. Gutta Flow 2 did not show any significant antimicrobial action. Maximum and minimum flow was shown by AH Plus and CRCS respectively.

CONCLUSION

Highest microbial inhibition was shown by (CRCS), followed by MTA Fillapex and AH Plus. Gutta Flow 2 did not show any inhibition of E. faecalis by ADT. Maximum reduction in antibacterial property with time against E. faecalis was seen with AH Plus. Maximum flow was shown by AH Plus and minimum by CRCS.

A Comparative Evaluation of Sealing Ability of New MTA Based Sealers with Conventional Resin Based Sealer: An In-vitro Study

INTRODUCTION

Root canal obturation is the most important step in the root canal treatment that aims to obtain a complete hermetic seal and to prevent the re-growth of microorganisms in the root canal system. To accomplish this, many endodontic obturation materials and sealers are being used.

AIM

To evaluate and compare the apical microleakage of a resin based sealer; Adseal with Mineral Trioxide Aggregate (MTA) based sealers; Pro root MTA and MTA Fillapex.

MATERIALS AND METHODS

Total 75 extracted human single rooted teeth were taken and decoronated at cemento-enamel junction. The access cavities and biomechanical preparation were performed using endodontic rotary system. The teeth were randomly divided into five groups with n=15; Group I - Gutta-percha and Adseal sealer; Group II - Gutta-percha and MTA Fillapex; Group III- Gutta-percha and Pro root MTA; Group IV- Gutta-percha without sealer (positive control group); Group V- Root canal remained empty (negative control). All the specimens were stored at 37(0)C with 100% humidity for one week. All root surfaces except the apical 2mm were covered with two layers of nail varnish and then immersed in an aqueous solution of 2% methylene blue dye for 72 hours. Roots were longitudinally split using a diamond disk. Linear apical dye penetration was measured under Stereomicroscope at 40X magnification.

STATISTICAL ANALYSIS

The data obtained was subjected to statistical analysis using paried t-test, ANOVA for interclass comparison, with SPSS statistical software (version 20.0).

RESULTS

The intraobserver reliability was found to be insignificant in each of the triplicate study of all the three study samples. MTA Fillapex group showed maxmium apical microleakage followed by Pro root MTA and Adseal sealer.

CONCLUSION

The results concluded that Adseal sealer showed minimal dye penetration followed by Pro root MTA and MTA Fillapex. Thus, concluding that Adseal sealer is better in apical sealing than Pro root MTA and MTA Fillapex.

Bioceramic-Based Root Canal Sealers: A Review

Bioceramic-based root canal sealers are considered to be an advantageous technology in endodontics. The aim of this review was to consider laboratory experiments and clinical studies of these sealers. An extensive search of the endodontic literature was made to identify publications related to bioceramic-based root canal sealers. The outcome of laboratory and clinical studies on the biological and physical properties of bioceramic-based sealers along with comparative studies with other sealers was assessed. Several studies were evaluated covering different properties of bioceramic-based sealers including physical properties, biocompatibility, sealing ability, adhesion, solubility, and antibacterial efficacy. Bioceramic-based sealers were found to be biocompatible and comparable to other commercial sealers. The clinical outcomes associated with the use of bioceramic-based root canal sealers are not established in the literature.

Use of calcium-containing endodontic sealers as apical barrier in fluid-contaminated wide-open apices

PURPOSE

The sealing of wide-open apex roots is still a challenge and requires the use of apical barrier techniques. The aim was to evaluate ex vivo the sealing and the apical morphology of 3 commercial calcium oxide (CaO)-containing sealers - namely, 2 zinc oxide-based (CRCS and Sealapex) and a calcium silicate MTA-based (TechBiosealer Endo) - placed in wet root canals with artificial wide-open apices.


METHODS

Thirty human single-rooted teeth were shaped with Protaper and an artificial open apex (diameter size 110) was created. Each root was inserted in a custom-designed support containing simulated body fluid (Hank's balanced salt solution, HBSS) at the bottom simulating the presence of periapical fluid in the canal. Each sealer (TechBiosealer Endo, CRCS, Sealapex) was compacted to the apical 5 mm and the filled roots stored in HBSS at 37°C. The sealing was evaluated as microinfiltrated fluid since 24 hours up to 6 months using a high-precision digital fluid flow meter. The sealers were also studied for setting time in HBSS, calcium releasing (statistical analysis by 2-way ANOVA followed by Student-Newman-Keuls test, P<0.05) and surface morpho-chemistry by ESEM-EDX and OM analysis.


RESULTS

All sealers showed a stable seal. TechBiosealer Endo maintained a better seal than the other materials (P<0.05) and ESEM-EDX and OM analyses showed the presence of apatite deposits.


CONCLUSIONS

The clinical use of hydraulic hydrophilic MTA-based sealers can be recommended to stop/reduce the fluid flow rate through the apex. The artificial apical barrier in wet wide apices is a suitable technique able to seal wet root canals.

Tricalcium silicate cements with resins and alternative radiopacifiers

OBJECTIVE

The objectives of this study were the investigation of the setting mechanisms and characterization of radiopacified tricalcium silicate-based materials mixed with different liquid vehicles.

METHODS

Tricalcium silicate cement replaced with 20% of either zirconium oxide or barium zirconate radiopacifier was investigated. The cements were mixed with water, an epoxy resin, or a light-cured Bis-GMA-based resin. The setting mechanism and characterization of set materials after immersion in Hank's balanced salt solution (HBSS) for 28 days were investigated by scanning electron microscopy of polished specimens and x-ray diffraction analysis. The bioactivity and surface microstructure of cements immersed in HBSS or water were also assessed by similar techniques together with leaching in solution investigated by inductively coupled plasma emission spectroscopy.

RESULTS

The formation of calcium hydroxide as a by-product of cement reaction was affected by the type of radiopacifier and also by the resin vehicle used. Barium zirconate enhanced the formation of calcium hydroxide as indicated by both scanning electron microscopy and x-ray diffraction analysis. The use of resins as vehicles reduced the formation of calcium hydroxide, with the Bis-GMA-based resin being mostly affected. Calcium hydroxide was deposited on the material surface regardless of the type of vehicle used. Formation of beta calcium phosphate was observed on materials containing barium zirconate radiopacifier immersed in HBSS. Inductively coupled plasma emission spectroscopy analysis showed high levels of calcium leached from materials by using water and light-curable resin as mixing vehicles. Barium was leached in solution, with the highest amount from the water-based mixtures. Zirconium leaching was negligible in materials containing zirconium oxide as radiopacifier, but leaching of zirconium was measurable in materials by using barium zirconate with tricalcium silicate.

CONCLUSIONS

The resin type and composition of the radiopacifier affect the calcium releasing ability and bioactivity of tricalcium silicate cements. Barium was leached in solution with barium zirconate radiopacified variants. Light-cured Bis-GMA-based resins did not exhibit cement hydration; however, they encouraged leaching of calcium ions in solution and promoted surface deposition of calcium phosphate.

Effect of Er,Cr:YSGG laser irradiation on apical sealing ability of calcium silicatecontaining endodontic materials in root-end cavities

The aim of this research was to evaluate the apical sealing abilities of 60 root-end cavities filled with mineral trioxide aggregate (MTA) and iRoot BP cements after treated with either 17% EDTA solution or Er,Cr:YSGG laser irradiation. After the filling procedure, apical leakage quantity was measured at 4 weeks using a fluid filtration method. One root from each group was processed for scanning electron microscopy and energy dispersive X-ray spectroscopy analyses. Both EDTA/MTA and laser irradiation/MTA combinations showed significantly lower microleakage than EDTA/iRoot BP and laser irradiation/iRoot BP combinations (p<0.05). Between groups of the same filling material, there were no significant differences among specimens treated with EDTA or laser (p>0.05). Both MTA and iRoot-BP demonstrated tag-like structures within the dentinal tubules when used in conjunction with EDTA.

The sealing ability of MTA apical plugs exposed to a phosphate-buffered saline

OBJECTIVE

The aim of this study was to evaluate the influence of exposure of the mineral trioxide aggregate (MTA) - with and without calcium chloride (CaCl2) - to phosphate-buffered saline (PBS) on the apical microleakage using a glucose leakage system.

MATERIAL AND METHODS

Sixty root segments were randomly divided into 4 experimental groups (n=15). After resecting the apical segments and enlarging the canals with Gates-Glidden drills, the apical cavities were filled with MTA with or without CaCl2 and the root canals were dressed with a moistened cotton pellet or PBS, as follows: 1) MTA/cotton pellet; 2) MTA/PBS; 3) MTA+10%CaCl2/cotton pellet; 4) MTA+10%CaCl2/PBS. All root segments were introduced in floral foams moistened with PBS. After 2 months, all root segments were prepared to evaluate the glucose leakage along the apical plugs. The amount of glucose leakage was measured following an enzymatic reaction and quantified by a spectrophotometer. Four roots were used as controls. The data were analyzed using Kruskal-Wallis and Mann-Whitney tests (p<0.05).

RESULTS

There were no differences between groups 1 and 2 (p>0.05), and 3 and 4 (p>0.05). The addition of CaCl2 to the MTA significantly decreased its sealing ability (p<0.05).

CONCLUSION

The interaction with PBS did not improve the MTA sealing ability. The addition of CaCl2 to the MTA negatively influenced the apical seal.

Retreatability of 2 mineral trioxide aggregate-based root canal sealers: a cone-beam computed tomography analysis

INTRODUCTION

The retreatability of recent calcium silicate or mineral trioxide aggregate (MTA) sealers has not yet been assessed. The aim of this study was to evaluate the removal of 2 MTA-based sealers (MTA Fillapex [Angelus Soluções Odontológicas, Londrina, PR, Brazil] and MTA Plus [Prevest-Denpro, Jammu City, India]) using a rotary retreatment system, considering an epoxy resin sealer (AH Plus [Dentsply Maillefer, Ballaigues, Switzerland]) as the standard for comparison.

METHODS

Root canals in 45 single-rooted teeth were instrumented using a rotary nickel-titanium system (MTwo; VDW GmbH, Munich, Germany) and obturated with gutta-percha using one of the following sealers (n = 15): group 1, MTA Fillapex; group 2, MTA Plus; and group 3, AH Plus. The teeth were scanned using a cone-beam computed tomography scanner. After 2 months, the root canals were retreated with a rotary retreatment system (ProTaper Universal Retreatment; Dentsply Maillefer, Ballaigues, Switzerland) and a second cone-beam computed tomography scan was performed to assess the amount of remaining root filling material (in percentage) and dentin removal (in cubic millimeters). The time taken to reach the working length was calculated in minutes. Group comparisons were performed using 1-way analysis of variance and the Student-Newman-Keuls post hoc test (P = .05).

RESULTS

There was a significant difference in the amount of remaining root filling material between the 3 groups (P < .05), with group 1 showing the least amount of root filling material (1.8% ± 0.22%) and group 3 showing the highest (10.4% ± 0.71%). The amount of dentin removal and the time taken to reach the working length was significantly higher in group 3 than in groups 1 and 2 (P < .05). There was no significant difference between groups 1 and 2 in these outcome variables (P > .05).

CONCLUSIONS

The rotary retreatment system evaluated was not able to completely remove any of the sealers. MTA Fillapex showed less remaining root filling material than MTA Plus.

Effect of phosphate-buffered saline on push-out bond strength of a new bioceramic sealer to root canal dentin

BACKGROUND

The aim of this study was to compare push-out bond strength of a new bioceramic endodontic sealer, EndoSequence BC sealer (Brasseler USA, Savannah, GA), used with gutta-percha in the presence or absence of phosphate-buffered saline solution (PBS) within the root canals.

MATERIALS AND METHODS

Forty single-rooted human teeth were prepared and randomly divided into four groups. Samples in groups 1 and 2 were dried, but those in groups 3 and 4 were moistened with PBS before obturation. All root canals were obturated with gutta-percha/EndoSequence BC sealer. The specimens were stored in PBS for 7 days in groups 1 and 3 and for 2 months in groups 2 and 4. Push-out bond strength values and failure modes were evaluated. The data on push-out bond strength were analyzed using two-way ANOVA.

RESULTS

The mean value for the bond strength of the obturation material in moistened canals was significantly higher than that in dried ones at 1 week (P = 0.00). Contrarily, there was no significant difference between dried and moistened root canals at 2 months (P = 0.61). In dried canals, bond strength increased significantly with time but in moistened ones, the difference was not significant. Inspection of the specimens revealed the bond failure to be mainly cohesive for all groups.

CONCLUSION

The presence of PBS within the root canals increased the bond strength of EndoSequence BC sealer/gutta-percha at 1 week. However, no difference was found between the bond strength of EndoSequence BC sealer/gutta-percha in the presence or absence of PBS in the root canals at 2 months.

The effect of prior calcium hydroxide intracanal placement on the bond strength of two calcium silicate-based and an epoxy resin-based endodontic sealer

INTRODUCTION

The aim of this study was to investigate the effect of prior calcium hydroxide (Ca[OH](2)) intracanal placement on the bond strength of AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany), iRoot SP (Innovative Bioceramix, Vancouver, BC, Canada), and MTA Fillapex (Angelus Soluções Odontológicas, Londrina, PR, Brazil).

METHODS

The root canals of 90 human incisor teeth were prepared with the ProTaper System (Dentsply Maillefer, Ballaigues, Switzerland) up to a master apical file size of F5. Canals were filled using the single-cone technique either immediately (the control group, n = 30) or after a 7-day Ca(OH)(2) placement. Ca(OH)(2) removal was performed either manually using F5 with distilled water irrigation (the Ca[OH](2) group, n = 30) or manually using Protaper F5 followed by passive ultrasonic irrigation with 2.5 % NaOCl with a final flush of 17 % EDTA and then distilled water (the PUI group, n = 30). After obturation, a 2-mm-thick middle section of each root was then subjected to push-out testing.

RESULTS

Using 1-way analysis of variance, AH Plus showed a higher bond strength than iRoot SP and MTA Fillapex in the control group (P < .05). With prior Ca(OH)(2) placement, AH Plus and iRoot SP showed a similar bond strength (P > .05), which was higher than MTA Fillapex (P < .05).

CONCLUSIONS

Prior Ca(OH)(2) placement seemed to improve the dislodgment resistance of iRoot SP but did not affect AH Plus and MTA Fillapex.

Dentin-cement interfacial interaction: calcium silicates and polyalkenoates

The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the "mineral infiltration zone", where the alkaline caustic effect of the calcium silicate cement's hydration products degrades the collagenous component of the interfacial dentin. This degradation leads to the formation of a porous structure which facilitates the permeation of high concentrations of Ca(2+), OH(-), and CO(3) (2-) ions, leading to increased mineralization in this region. Comparison of the dentin-restorative interfaces shows that there is a dentin-mineral infiltration with the Biodentine, whereas polyacrylic and tartaric acids and their salts characterize the penetration of the GIC. A new type of interfacial interaction, "the mineral infiltration zone", is suggested for these calcium-silicate-based cements.

Apical sealing of root canal fillings performed with five different endodontic sealers: analysis by fluid filtration

Objectives

To evaluate the sealing ability of five root canal sealers, including two experimental cements (MBP and MTA-Obtura) using the fluid filtration method.

Material and Methods

Teeth were divided into 5 study groups: G1-AH Plus; G2-Acroseal; G3-Sealapex; G4-MBP; G5-MTA-Obtura; and two controls. Chemical-mechanical preparation was performed with ProFile rotary nickel-titanium instruments 1 mm short of the apical foramen. The sealing ability was evaluated by fluid filtration at 15, 30, and 60 days.

Results

The statistical analysis showed significant difference between the materials at different periods (p<0.05). AH Plus and MBP had similar leakage values at 15 and 60 days, alternating with significant reduction at 30 days, while the other materials showed progressive increase in leakage values. Acroseal and Sealapex presented the best results at 15 days and the worst at 60 days.

Conclusions

All sealers evaluated presented fluid leakage, with AH Plus and MBP showing the best results at the end of the experimental period. Acroseal, Sealapex, and MTA-Obtura presented increase in leakage values at longer observation periods.

Push-out bond strength of gutta-percha with a new bioceramic sealer in the presence or absence of smear layer

The purpose of this study was to compare the bond strength of a new bioceramic sealer (EndoSequence BC Sealer) and AH Plus in the presence or absence of smear layer. Extracted single-rooted human teeth were prepared and randomly divided into four groups. In groups 1 and 3, the root canals were finally irrigated with 5.25% NaOCl and smear layer was not removed, but in groups 2 and 4, the root canals were finally irrigated with 17% EDTA followed by 5.25% NaOCl in order to remove the smear layer. In groups 1 and 2, the root canals were obturated with gutta-percha/AH Plus, but in groups 3 and 4, obturation was performed with gutta-percha/EndoSequence BC Sealer. Push-out bond strength and failure modes were evaluated. The bond strength of gutta-percha/AH Plus and gutta-percha/EndoSequence BC Sealer was not significantly different (P = 0.89). The presence or absence of smear layer did not significantly affect the bond strength of filling materials (P = 0.69). The mode of bond failure was mainly cohesive for all groups. In conclusion, the bond strength of the new bioceramic sealer was equal to that of AH Plus with or without the smear layer.

Dynamic sealing ability of MTA root canal sealer

AIMS

To evaluate (i) the sealing ability of two sealers, mineral trioxide aggregate sealer (MTAS) and Pulp Canal Sealer (PCS), used with gutta-percha utilizing the fluid filtration method, (ii) leaching and surface characteristics in Hank's balanced salt solution (HBSS) over a period of time.

METHODOLOGY

Surface characteristics in HBSS were evaluated under the scanning electron microscope after 1 and 28 days, and the leaching of both sealers were assessed by inductively coupled plasma atomic absorption spectrometry (ICP-AAS). In addition, 24 single rooted extracted teeth were root filled using warm vertical compaction with either MTAS or PCS used as sealers with gutta-percha. Four teeth were used as positive and negative controls. Sealing ability was evaluated after 1 or 28 days using the fluid filtration method.

RESULTS

Mineral trioxide aggregate sealer exhibited crystalline deposits rich in calcium and phosphorus on its surface when in contact with a physiological solution. These crystalline deposits were absent in PCS and on MTAS stored at 100% humidity. The sealing ability of MTAS was similar to that of PCS.

CONCLUSIONS

The novel sealer based on mineral trioxide aggregate had comparable sealing ability to a proprietary brand sealer cement. In contact with a simulated body fluid, the MTA sealer released calcium ions in solution that encouraged the deposition of calcium phosphate crystals.

MTA and F-doped MTA cements used as sealers with warm gutta-percha. Long-term study of sealing ability

AIM

To evaluate the long-term sealing ability (up to 6 months) of two experimental calcium silicate MTA cements used as root canal sealers in association with warm gutta-percha.

METHODOLOGY

Calcium silicate (MTA) and calcium-fluoro-silicate powders were prepared. Sodium fluoride was included in FMTA (Fluoride-doped Mineral Trioxide Aggregate) as an expansive and retardant agent. Single-rooted teeth were instrumented with NiTi rotary instruments, filled with warm gutta-percha in association with one of the experimental sealers or with AH Plus as a control (n = 20 for each sealer) and stored at 37 °C. Sealing was assessed at 24, 48 h, 1, 2 weeks and 1, 3, 6 months by a fluid filtration method. Scanning electron microscopy with energy dispersive analysis (SEM/EDX) was used to study the dentine/sealer interface of roots stored for 6 months and the surface of cement disks stored for 24 h.

RESULTS

All sealers revealed a statistically significant reduction (P < 0.05) in fluid filtration after the first 2 weeks. No statistically significant differences were observed between FMTA and AH Plus at all analysis times. At short times (24, 48-h), no statistically significant differences were found between the experimental cements and AH Plus. At long-term evaluations (1, 3, 6 months), FMTA and AH Plus sealed significantly better (P < 0.05) than MTA. FMTA was associated with lower fluid filtration rates, and the seal was stable from 48 h to 6 months, thus proving the most effective material. Scanning electron microscopy with energy dispersive analysis of root sections filled with calcium silicate sealers revealed the formation of a blend layer of gutta-percha and cement consequent to the warm gutta-percha condensation technique. Scanning electron microscopy with energy dispersive analysis of 24-h-stored disks identified a Ca-rich coating on the outer surface consisting of globular particles (calcium hydroxide and calcium carbonate), and a deeper internal Ca- and Si-rich region consisting of needle-like ettringite crystals and round formations of calcium silicate hydrate gel.

CONCLUSION

Fluoride-doped MTA demonstrated stable sealing during a period of up to 6 months and significantly better than conventional calcium silicate MTA cements and comparable to AH Plus. The study supports the suitability of calcium silicate MTA cements as sealers in association with warm gutta-percha for root filling.

Environmental scanning electron microscopy connected with energy dispersive x-ray analysis and Raman techniques to study ProRoot mineral trioxide aggregate and calcium silicate cements in wet conditions and in real time

INTRODUCTION

ProRoot mineral trioxide aggregate (MTA) and calcium silicate cements are able to set in a moist environment. The aim of the study was to examine the surface structure and composition of a cement paste under wet conditions and in real time during setting by environmental scanning electron microscopy connected with energy dispersive x-ray analysis (ESEM-EDX) and micro-Raman techniques.

METHODS

White ProRoot MTA and experimental white tetrasilicate cement (wTC) and wTC containing bismuth oxide (wTC-Bi) were studied. Cement disks were analyzed 10 minutes after powder-liquid mixing (freshly prepared samples) and after immersion in Dulbecco phosphate-buffered saline at 37 degrees C for 24 hours (24-hour-aged samples).

RESULTS

Freshly prepared wet cements at ESEM-EDX exposed an irregular surface (displaying calcium, silicon, aluminum, chlorine reflexes, and bismuth traces in MTA and wTC-Bi) with needle-like and cubic-hexagonal shaped crystals. Aggregates of spheroidal Ca-P-rich crystals (spherulites) appeared on the surface of 24-hour-aged samples. The starting unhydrated powders displayed the typical Raman bands of Portland cement components: alite, belite, and calcium sulfate (only as anhydrite in MTA and as both anhydrite and gypsum in wTC and wTC-Bi). MTA powder showed higher amount of calcium carbonate and lower quantities of anhydrite and higher crystallinity of the silicate component, leading to a slower hydration reaction. Products/markers of hydration reactions were present on fresh samples; ettringite formed on the surface of all the cements; calcium hydroxide (portlandite) was detected only on the surface of wTC, but no conclusion can be drawn on wTC-Bi and MTA because of the interference of bismuth oxide. Calcium phosphate and calcite/aragonite bands were detected on all 24-hour-aged cements; portlandite was no longer detected on wTC.

CONCLUSIONS

ESEM and micro-Raman are powerful and suitable techniques to investigate endodontic calcium silicate hydrated cements in real time and in their humid state without inducing artifacts by sample preparation. The formation of apatite spherulites on calcium silicate cements might have clinical relevance.