Comparative analysis of the particle size and shape of commercially available mineral trioxide aggregates and Portland cement: a study with a flow particle image analyzer

Comprehensive investigation of recycled PVC powder

This study constitutes a comprehensive investigation centred on comprehending the behaviour and characteristics of recycled polyvinyl chloride (PVC) powders. The overarching objective is to successfully conclude the initial research phase, during which PVC-coated fabric offcuts undergo a transformation into PVC powder while achieving complete separation from polyethylene terephthalate fibres. The study entails a qualitative description of the morphology of PVC powder particles, employing an optical microscope to distinguish the diverse shapes exhibited by these particles. The optical microscope observations of PVC powder reveal a distinct array of non-spherical particles characterized by flat, elongated shapes. These high-magnification images unveil the intricate morphological features of the particles, highlighting their irregular shapes. Subsequently, a quantitative analysis of PVC particle size distribution is performed, comparing results from optical microscopy with those obtained through mechanical sieving. The qualitative and quantitative findings obtained provide robust evidence supporting the correlation and confirm that most particles are smaller than 600 µm (93.6%) using an optical microscope and the sieving process (96.39%). The greatest fraction (83.44%) is in the size range between 200 and 600 µm. Assessing flowability, another significant aspect in the evaluation of powders, provides insights into its behaviour and interparticle interactions. The flowability results indicate a Compressibility Index of approximately 26.84%, which suggests poor flowability. This means that the powder is likely to encounter difficulties in flowing freely. This finding is in line with the Hausner ratio, which measures 1.37. This investigation of recycled PVC powder will offer insights into the potential applications and processing considerations of this powder. More concretely, the use of recycled PVC powder shows promise as a viable alternative to conventional PVC resin in plastisol formulations, offering the potential to maintain the properties of the final PVC product without adverse effects.

Mechanical and Physicochemical Characteristics of a Novel Premixed Calcium Silicate Sealer

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

Shear bond strength of calcium silicate-based cements to composite resin using a universal adhesive in different application modes: an in vitro study

BACKGROUND

To assess the shear bond strength (SBS) of four calcium silicate-based cements (CSCs) to composite resin using a universal adhesive in self-etch (SE) and etch-and-rinse (ER) modes and to evaluate surface microstructure and chemical composition of CSCs after acid-etching.

METHODS

In total, 30 specimens of each cement, Biodentine (BD), mineral trioxide aggregate (MTA) Angelus (MTA-A), ProRoot MTA (MTA-P) and MTA Repair HP (MTA-HP), were prepared and assigned into 2 groups (n = 15) according to universal adhesive (Clearfil Universal Bond Quick) applied in SE and ER mode. After composite resin (Clearfil Majesty Esthetic) was applied, the SBS was measured. Scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) analysis was used to evaluate the changes in surface structure and elemental composition.

RESULTS

MTA-P demonstrated significantly higher SBS than all CSCs, except for MTA-HP in the SE mode. The ER mode exhibited significantly higher SBS compared to the SE mode for MTA-P and MTA-A. Acid-etching caused morphological differences and affected elemental distribution.

CONCLUSIONS

MTA-P may be a more suitable pulp capping material due to its superior SBS compared to BD and MTA-A. The application of a universal adhesive in ER mode may be suggested to increase the SBS of MTA-P and MTA-A to composite resin.

Effects of ethylenediaminetetraacetic acid, citric acid, and etidronic acid on root dentin mineral content and bond strength of a bioceramic-based sealer: A scanning electron microscopy-energy dispersive spectroscopy study

Background

This study assessed the impact of chelating agents, 17% ethylenediaminetetraacetic acid (EDTA), 10% citric acid (CA), and 18% etidronic acid (HEDP), on root dentin mineral content. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) was applied to analyze changes, and the push-out bond strength test was used to measure dentin adhesion of Well-Root ST, a bioceramic root canal sealer.

Methods

A total of 80 extracted single-rooted lower premolar teeth were included in this study and randomly divided into four groups (n=20): group 1 (17% EDTA), group 2 (10% CA), group 3 (18% HEDP), and group 4 (distilled water, control). After irrigation and drying, SEM-EDS was applied to analyze eight samples from each group at coronal, middle, and apical root regions for mineral content and SEM images. The remaining 12 samples underwent a push-out bond strength test using Well-Root ST sealer and gutta-percha. Kruskal-Wallis and Dunn's tests were used for statistical analyses.

Results

Statistically significant differences were found between groups (P<0.05). SEM-EDS showed significant differences in C, O, Ca, P, and Ca/P content, with no significant differences in Na and Mg. Push-out bond strength was significantly higher in the 17% EDTA, 10% CA, and 18% HEDP groups compared to the control group, with no significant differences between chelating agents.

Conclusion

Chelating agents altered root dentin mineral content and improved the adhesive properties of the bioceramic sealer. These findings highlight the importance of considering the selection and use of chelating agents in the clinical practice for root canal treatment.

Influence of Bioceramic Cements on the Quality of Obturation of the Immature Tooth: An In Vitro Microscopic and Tomographic Study

The present in vitro study focuses on the filling ability of three different bioceramic cements with or without the addition of a bioceramic sealer in an open apex model on the marginal apical adaptation, tubule infiltrations, and void distributions as well as the interface between the cement and the sealer materials. To this end, sixty mandibular premolars were used. MTA-Biorep (BR), Biodentine (BD), and Well-Root Putty (WR) were used to obturate the open apex model with or without the addition of a bioceramic sealer, namely TotalFill® BC sealer™ (TF). A digital optical microscope and scanning electron microscope (SEM) were used to investigate the cement-dentin interface, marginal apical adaptation, and the material infiltration into the dentinal tubules. Micro-computed X-ray tomography and digital optical microscopy were used to investigate the cement-sealer interface. The results were analyzed by using the Kruskal-Wallis test. No significant difference was found between the groups for the marginal apical adaptation quality (p > 0.05). Good adaptation of the dentin-cement interface was found for all tested groups and the sealer was placed between the cement material and dentinal walls. All the groups demonstrated some infiltrations into the dentinal tubules at the coronal part except for the BR group. A good internal interface was found between the cement and the sealer with the presence of voids at the external interface. A larger number of voids were found in the case of the BD-TF group compared to each of the other two groups (p < 0.05). Within the limitations of the present in vitro study, all the groups demonstrated good marginal apical adaptation. The use of a sealer in an open apex does not guarantee good filling and, in addition, creates voids at the external interfaces with the dental walls when the premixed sealer is used with powder-liquid cement systems. The use of a premixed bioceramic cement could offer fewer complications than when a powder-liquid cement system is used.

The osteoinductive potential of different root-filling materials in a rat femur model

In pediatric dentistry, the enduring success of root-end filling materials employed for the establishment of apical plugs in immature teeth undergoing endodontic intervention is contingent upon their possessing a robust osteoinductive capacity. Hence, the primary objective of this study was to histologically assess the osteoinductive potential of four distinct dental materials, specifically recommended for retrograde filling applications, utilizing an animal hard tissue model. Within the designed experimental model, two bone defects measuring 2 mm in diameter and 2 mm in depth were created in both femurs of a cohort comprising 21 male Wistar albino rats. The first defect in the right femur was left blank as the control group, and Neo MTA Plus was placed in the second defect. The EndoSequence BCRRM Fast Set Putty was placed in the first of the defects on the left femur, and Endo Repair was placed in the second defect. Subjects were sacrificed after 7, 14, and 28 days of follow-up, and sections were examined to assess the degree of inflammation, connective tissue formation, and new bone formation. The data were statistically evaluated with Kruskal‒Wallis and post hoc Dunn's tests using SPSS 12 software. The bone healing levels of the Neo MTA Plus group were significantly higher than those of the other groups in all periods (p < 0.05). Bone organization in all groups decreased over time, and fibrous tissue was enriched. The results of this study demonstrate that NeoMta Plus has superior osteoinductive properties compared to other materials but that EndoSequence and Endo Repair have the potential to be developed.

Preparation and properties of the fine ground strontium-based endodontic cements

In this study, fine powders of tristrontium aluminate (S3A) and distrontium cerate (S2Ce) cement were prepared using a dry grinding process, and their mechanical and ion dissolution properties were estimated. Fine cements showed the particles about 10 μm in diameter or smaller with sharp particle size distribution curves. The setting reaction of the fine cements was rapid; therefore, a 0.1% w/v of citric acid solution was used as the retarder. The compressive strengths of the fine cements were improved compared to those of the coarse cements at both 1 and 28 days after mixing at a water/powder ratio (W/P) of 0.4. The dissolution of Sr and Al ions from fine S3A cement was enhanced. However, the relative flowability decreases with fine grinding. Further studies on flowability, handling property are required. Additionally, the biological effects of endodontic cement should be studied both in vitro and in vivo.

Intratubular crystal formation in the exposed dentin from nano-sized calcium silicate for dentin hypersensitivity treatment

The aim of this study is to evaluate intratubular crystal formation from the experimental material consisting of dicalcium silicate (C2S) and tricalcium silicate (C3S) with nano-scaled particle size. A total of twenty-four specimens were made by isolating 8 mm of the cervical part centered at the cementoenamel junction of extracted premolars. Twelve specimens were not treated and considered as control. The experimental material was applied to the other twelve specimens by brushing for 10,000 strokes. Each group was randomly divided into four subgroups according to the period of immersion in phosphate buffer saline (PBS) for 1, 30, 60, and 90 days each. The specimens were sectioned longitudinally and examined with scanning electron microscopy and energy dispersion X-ray spectroscopy. The intratubular crystal were formed in PBS and densely filled the dentinal tubules over time. The crystal formation occurred at a depth of more than 50 μm from the dentin surface. The Ca/P ratio of formed intratubular crystals was 1.68 after 3 months. The experimental material consisting of C2S and C3S with a nanoscale particle size can form hydroxyapatite-like crystals in dentinal tubules in PBS, and there is a possibility of reducing dentin hypersensitivity by blocking the dentinal fluid flow.

Utility of biphasic calcium phosphate cement as a seal for root-end filling

The recently developed biphasic calcium phosphate cement (BCPC) consists of α-tricalcium phosphate-tetracalcium phosphate as the solid phase and calcium phosphate solution as the liquid phase. BCPC powder is composed of a single solid solution with a monomodal size distribution. Here, we used a bacterial leakage model to examine the utility of BCPC as a seal for root-end filling. We prepared large (median particle size=9.96 µm; BCPC-L) and small (median particle size=4.84 µm; BCPC-S) BCPC powders. In total, 45 single-rooted teeth were instrumented, resected at the root-end, and retrofilled with experimental materials. Mineral trioxide aggregate (MTA) was used as the control. After visual confirmation of BCPC powder size and retrofilling quality by microscopy, bacterial leakage tests were conducted using Enterococcus faecalis. The bacterial leakage tests did not reveal any significant differences between BCPC-S and MTA. Our findings suggest that BCPC-S is useful for root-end filling.

Effect of Different Mixing Methods on Physicochemical Properties of Mineral Trioxide Aggregate: A Systematic Review

Background

Mineral trioxide aggregate (MTA) is a commonly used endodontic biomaterial. The physicochemical properties of MTA have a crucial role in designating clinical outcome, and different factors can affect these properties. Various methods have been used for mixing MTA, including manual, mechanical, and ultrasonic. The aim of this systematic review was to evaluate the effect of different mixing methods on the physicochemical properties of MTA.

Materials and Methods

Electronic databases including PubMed, Embase, Web of Science, and Scopus were searched up to May 2022. In order to cover gray literature, the ProQuest and Google Scholar databases were also searched to detect theses and conference proceedings. For quality assessment of the included studies, we used a modified version of the Cochrane risk of bias tool for randomized controlled trials (RCTs). Experimental studies which had assessed at least one property of MTA and compared at least two different mixing methods of MTA were included in this study. All animal studies, reviews, case reports, and case series were excluded.

Results

Fourteen studies were included. The results showed that the ultrasonic mixing method significantly improved some MTA characteristics, including microhardness, flowability, solubility, setting time, and porosity. However, the mechanical mixing method improved other properties including flowability, solubility, push-out bond strength, and hydration. The manual mixing method showed inferior results compared to other mixing methods in terms of microhardness, flowability, solubility, setting time, push-out bond strength, porosity, and hydration. Different mixing methods had a similar effect on compressive strength, sealing ability, pH and calcium ion release, volume change, film thickness, and flexural strength of MTA.

Conclusion

Mechanical and ultrasonic mixing methods are superior to the manual mixing method in terms of improving physicochemical properties of MTA. No report of selection bias and varieties in methodologies were limitations of evidence.

Push-out bond strength of two calcium silicate-based cements used for repair of artificial furcal perforation following different power outputs of Nd:YAG laser

Proper bond strength of endodontic materials is an essential factor in the final success of root canal treatments, including perforation repairs. This study was designed to evaluate the effect of two power outputs of Nd:YAG laser (1064 nm) on push-out bond strength (PBS) of ProRoot mineral trioxide aggregate (MTA) and calcium-enriched mixture cement (CEM Cement) in the repair of artificial furcal perforations. This ex vivo study enrolled 66 extracted human molars. After preparing the access cavity, perforations were created on the floor of the pulp chamber with a diameter of 1.4 mm. The teeth were randomly distributed into the following six groups according to the repair material (MTA and CEM) and power output of laser irradiation (1 W and 1.5 W); A: MTA (case), B: CEM (case), C: Nd:YAG (1 W)/MTA, D: Nd:YAG (1 W)/CEM, E: Nd:YAG (1.5 W)/MTA, and F: Nd:YAG (1.5 W)/CEM. Then, a universal testing machine was utilized to assess the PBS. Data analysis was performed using ANOVA and T tests. Significant level was considered at P < 0.05. The highest mean ± SD of PBS was noted in Group Nd:YAG (1 W)/MTA (58.92 ± 36.13), followed by Nd:YAG (1.5 W)/MTA > Nd:YAG (1.5 W)/CEM > Nd:YAG (1 W)/CEM > MTA > and CEM. A significant difference was noted between laser and non-laser applications (P < 0.05). However, the increase of power output from 1 to 1.5 W had no significant influence on PBS (P > 0.05). The PBS of MTA groups was always significantly greater than that of CEM groups (P < 0.05). Although Nd:YAG laser irradiation positively influenced on PBS values in both material studied, increasing power output was not effective.

Push-Out Bond Strength of Calcium Silicate-Based Cements in the Presence or Absence of a Smear Layer

Objectives. Variations between the material compositions and the presence of a smear layer on the dentin surface may influence the bond strength of the material, thus this study evaluated the push-out bond strength of different calcium silicate materials to root dentin in the presence or absence of smear layer. Materials and Methods. The palatal canal of sixty maxillary first premolars were prepared and divided into three groups according to the materials to be used: ProRoot WMTA, Biodentine, and TotalFill FS. Each group was then divided into two subgroups; with and without a smear layer. Roots were sectioned into three slices and filled with the tested materials. Push-out bond strength of materials was measured by universal machine. Results. Bond strength of Biodentine was significantly higher than the MTA and TotalFill FS in the presence or absence of smear layer. Overall, removing the smear layer reduced the bond strength of the three materials. The reduction was significant for MTA and TotalFill FS but not for Biodentine. Conclusions. Biodentine demonstrated the highest bond strength to radicular dentin followed by MTA, and then TotalFill FS. Overall, removal of the smear layer from dentin surface reduced the bond strength of the calcium silicate root repair materials.

Morphological and Chemical Analysis of Different Types of Calcium Silicate-Based Cements

Objectives. Particle size and shape can influence the properties of materials. However, to improve the physicochemical and biological properties of mineral trioxide aggregate (MTA), silicate-based hydraulic cements were introduced. This study aimed to evaluate and compare the major constituents and crystalline structures along with the surface morphology of different types of calcium silicate-based cement (CSC). Materials and Methods. Six different types of CSC (white Portland cement, white ProRoot MTA, white MTA Angelus, Biodentine, and Endosequence, both putty and paste) were used in this study. Five samples of each material were analyzed in both uncured and cured cement using scanning electron microscopy/energy-dispersive X-ray (SEM/EDX), X-ray diffraction (XRD), and Fourier transform-infrared spectroscopy (FTIR). Results. SEM analysis showed that the surfaces of all materials consisted of particle sizes ranging from 0.194 μm to approximately 51.82 μm. The basic elements found in both uncured and cured cement of all tested materials using EDX were carbon, calcium, silicon, and oxygen. A difference was observed in the presence or absence of magnesium, aluminum, bismuth, zirconium, and tantalum. XRD showed that all tested materials were composed mainly of tricalcium silicate and dicalcium silicate, which are the main components of Portland cement. FTIR analysis showed aromatic rings, phosphine PH, alkyl halides, and alcohol O-H groups in all tested materials but at different wavenumbers. Conclusions. The different types of CSCs tested in this study were primarily modified types of Portland cement with the addition of radiopacifiers. ProRoot MTA and MTA Angelus contained bismuth oxide, Biodentine contains zirconium oxide, whereas Endosequence root repair materials (both putty and paste) contained zirconium oxide and tantalum oxide. Endosequence root repair materials showed smaller particle sizes than the other groups. White PC had the most irregular and large particle sizes. CSC had a smaller particle size, except for MTA Angelus. Clinical Relevance. The composition of CSC has a direct influence on the properties of these cements, which may affect the clinical outcome of the treatment.

Portland Cement: An Overview as a Root Repair Material

Portland cement (PC) is used in challenging endodontic situations in which preserving the health and functionality of pulp tissue is of considerable importance. PC forms the main component of mineral trioxide aggregate (MTA) and demonstrates similar desirable properties as an orthograde or retrograde filling material. PC is able to protect pulp against bacterial infiltration, induce reparative dentinogenesis, and form dentin bridge during the pulp healing process. The biocompatibility, bioactivity, and physical properties of PC have been investigated in vitro and in animal models, as well as in some limited clinical trials. This paper reviews Portland cement's structure and its characteristics and reaction in various environments and eventually accentuates the present concerns with this material. This bioactive endodontic cement has shown promising success rates compared to MTA; however, considerable modifications are required in order to improve its characteristics and expand its application scope as a root repair material. Hence, the extensive chemical modifications incorporated into PC composition to facilitate preparation and handling procedures are discussed. It is still important to further address the applicability, reliability, and cost-effectiveness of PC before transferring into day-to-day clinical practice.

Hydration reaction analysis of calcium-silicate-based materials using Scanning Electron Microscopy and X-ray Diffraction method

Background/Aim: The components of calcium silicate-based materials can be identified through X-Ray Diffraction Analysis. This study aimed to determine the hydration reactions and particle size of MTA Angelus, Biodentine, and NeoMTA Plus as calcium-silicate-based materials. Material and Methods: The powder and set cement samples using divergence and scatter slits of 1 ○ and a receiver slit of 0.10 mm. The scanning range was set at 5 ○ to 70 ○ , and ongoing scans for the theta-2theta range was performed with a scan speed of 2 ○ /minute (-1). The patterns obtained were analyzed using search-match software. The three most substantial peaks were used to identify hydration reactions and major crystalline structures. Also, Scanning Electron Microscope (SEM) analysis was performed and the particle size of set materials were determined using an image analysis software. Results: According to X-Ray Diffraction Analysis, the main components were determined as tricalcium silicate and dicalcium silicate in the three calcium silicate-based materials. We determined that the main components of the materials were similar. We also identified the extensive presence of tricalcium aluminate in MTA Angelus, calcium carbonate in Biodentine, and calcium phosphate salts in NeoMTA Plus. Furthermore, the results of the present particle analysis show that the calcium-silicate-based materials' distribution of particle count and size varies. Biodentine has the widest, and MTA Angelus has the narrowest particle size distribution range. NeoMTA Plus has the largest number of fine, large-sized particles (p < 0.0001), while MTA Angelus and Biodentine have a more homogeneous and non-statistically significant particle distribution range (p > 0.05). Conclusions: The present findings provide insight into variations in performance between different calcium-silicate-based materials.

Energy-Dispersive X-Ray Spectrometry Analysis and Radiopacity of Five Different Root Canal Sealers

Root canal sealers should have optimum adhesion to the root dentin, low cytotoxicity, sufficient radiopacity and high dimensional stability, which depend mainly on their chemical composition. The aims of this study were to evaluate the chemical composition of Syntex (Cerkamed, Stalowa Wola, Poland), Adseal (Meta Biomed, Cheongju-si, Korea), Sealapex (SybronEndo, Scafati, Italy), MTA Fillapex (Angelus, Londrina, Brazil) and GuttaFlow Bioseal (Coltene/Whaledent, Altstätten, Switzerland) and to determine their radiopacity comparatively. Stainless steel molds with an inner diameter of 5 mm and a depth of 2 mm were constructed. Tested root-canal sealers were mixed and poured into the molds. Following setting, digital periapical radiographs of the specimens (n=12) were taken under standard exposure conditions and the mean gray-values of specimens were measured using a computer graphics program. Then the specimens were examined by scanning electron microscopy, and Energy-dispersive X-ray analysis was performed. The data were analyzed using One-way ANOVA followed by Holm-Sidak multi-comparison test (p = 0.05). Sealapex showed higher calcium peak than MTA Fillapex, GuttaFlow Bioseal, Adseal and Syntex sealers. MTA Fillapex contained a highest amount of tungstate. Sealapex presented the highest radiopacity value among the tested materials (p < 0.05), whereas MTA Fillapex was the least radiopaque material (p < 0.05). Each root canal sealer contains different compositions of radiopacifiers including bismuth oxide, calcium tungstate and zirconium oxide. The tested root canal sealers had radiopacity values above the ISO-specified limit. Sealapex was the most radiopaque root canal sealer followed by GuttaFlow Bioseal, Syntex, Adseal and MTA Fillapex.

Effect of bioactive glass addition on the physical properties of mineral trioxide aggregate

Background

The addition of bioactive glass (BG), a highly bioactive material with remineralization potential, might improve the drawback of weakening property of mineral trioxide aggregates (MTA) when it encounters with body fluid. This study aims to evaluate the effect of BG addition on physical properties of MTA.

Methods

ProRoot (MTA), and MTA with various concentrations of BG (1, 2, 5 and 10% BG/MTA) were prepared. Simulated body fluid (SBF) was used to investigate the effect of the storage solution on dentin remineralization. Prepared specimens were examined as following; the push-out bond strength to dentin, compressive strength, setting time solubility and X-ray diffraction (XRD) analysis.

Results

The 2% BG/MTA showed higher push-out bond strengths than control group after 7 days of SBF storage. The 2% BG/MTA exhibited the highest compressive strength. Setting times were reduced in the 1 and 2% BG/MTA groups, and solubility of all experimental groups were clinically acceptable. In all groups, precipitates were observed in dentinal tubules via SEM. XRD showed the increased hydroxyapatite peaks in the 2, 5 and 10% BG/MTA groups.

Conclusion

It was verified that the BG-added MTA increased dentin push-out bond strength and compressive strength under SBF storage. The addition of BG did not negatively affect the MTA maturation reaction; it increased the amount of hydroxyapatite during SBF maturation.

In vitro comparison of physical, chemical, and mechanical properties of graphene nanoplatelet added Angelus mineral trioxide aggregate to pure Angelus mineral trioxide aggregate and calcium hydroxide

It is important to cover the pulp surface with a biocompatible material that is physically, mechanically, and chemically adequate. Graphene has the potential to form hard tissue, but at high doses, it shows toxic effects. It can be added to biocompatible materials at low doses to enhance their hard tissue forming potential. The aim of this study was to compare the physical, chemical, and mechanical properties of graphene nanoplatelet (GNP) added Angelus mineral trioxide aggregate (A-MTA) to pure A-MTA and calcium hydroxide. Homogeneous mixtures (created by adding +0.1 weight[wt]% and 0.3 wt% GNP to A-MTA), pure A-MTA, and Dycal were used. Three disc-shaped samples of each material were prepared using Teflon mold. Scanning electron microscope-energy dispersive X-ray (SEM-EDX), particle size, microhardness, and Fourier transform infrared spectroscopy (FTIR) analysis of the materials were performed in vitro. Data were analyzed using Kruskal-Wallis test followed by Conover test (p < .001). A-MTA and GNP added samples showed similar peaks in FTIR analysis. In the EDX analysis, the amount of carbon was observed with a higher increase at A-MTA + 0.3 wt% GNP than A-MTA + 0.1 wt% GNP. In the SEM image, hollow structure and particle size decreased as the amount of GNP increased; particle size was smaller at A-MTA + 0.3 wt% GNP than A-MTA + 0.1 wt% GNP (p < .001). A-MTA + 0.3 wt% GNP showed the highest microhardness while Dycal showed the lowest microhardness. The addition of GNP, a material with high potential for forming hard tissue, to the structure of capping materials can also positively contribute to the microhardness of the capping materials.

Calcium Silicate-Based Cements as Root Canal Medicament

Purpose

This study aims to retard the setting reaction of CSC by mixing it with 2% chlorhexidine gel (CHX) which will be used as an intracanal medicament, and to evaluate the removal of the experimental medicaments from the root canal.

Materials and Methods

White Portland cement, white ProRoot MTA and Biodentine were mixed with 2% CHX. The setting time, flowability and film thickness of the CSC/CHX mixture (experimental medicaments) were assessed and measured following the standards of ISO specification. Calcium ion release was measured using ICP-OES, while pH was tested using a pH meter. Moreover, twenty single-rooted teeth were filled with the experimental medicaments for seven days, then the medicaments were removed and the samples analyzed using SEM. Calcium hydroxide paste was used as a control.

Results

The setting time of the experimental medicaments was inhibited until 84 days. The calcium ion release of the experimental medicaments was significantly higher compared to the control over the period of 14 days (P<0.001). The mean pH value was above 11.45 for all tested materials over a period of 14 days, with no significant difference between them (P<0.05). There was no significant difference in film thickness of the experimental medicaments compared to the control (P> 0.05). However, the flowability of the experimental medicaments was significantly higher than the control (P<0.05). SEM showed no significant differences in the removal of the intracanal medicaments between all the tested groups.

Conclusion

The addition of 2% CHX to CSCs retarded or inhibited its setting reaction over a period of 84 days. The calcium ion release and flowability of these experimental medicaments was found to be better than calcium hydroxide. Removal of the intracanal medicaments from the root canal was successfully achieved in all groups. Therefore, these experimental medicaments have the potential to be used as an enhanced root canal medicament.

A micro-computed tomography evaluation of voids using calcium silicate-based materials in teeth with simulated internal root resorption

Objectives

The obturation quality of MTA, Biodentine, Total Fill BC root canal sealer (RCS), and warm gutta-percha (WGP) in teeth with simulated internal root resorption (IRR) was evaluated by using micro-computed tomography.

Materials and Methods

Standardized IRR cavities were created using 40 extracted maxillary central incisor teeth and randomly assigned into 4 groups (n = 10). IRR cavities were filled with MTA, Biodentine, Total Fill BC RCS (bulk-fill form) and WGP + Total Fill BC RCS. Percentage of voids between resorptive cavity walls and obturation material (external void), and inside the filling materials (internal voids) were measured.

Results

Total Fill BC sealer in the bulk-fill form presented significantly highest values of external and internal void percentages (p < 0.05). Biodentine showed a significantly lowest external void percentage (p < 0.05). WGP + Total Fill BC RCS presented significantly lower values of internal void percentages than all groups (p < 0.05), except Biodentine (p > 0.05).

Conclusion

None of the filling materials were created void-free obturation in resorption cavities. Biodentine may favor its application in teeth with IRR over Angelus MTA and bulk-fill form of Total Fill BC.

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.

Initial inflammatory response after the pulpotomy of rat molars with MTA or ferric sulfate

PURPOSE

To compare, both qualitatively and quantitatively, the inflammatory cells, vascular density and IL-6 immunolabeled cells present in the pulp after pulpotomy with white MTA versus 15.5% ferric sulfate (FS).

METHODOLOGY

Forty-eight mandibular first molars from 24 Wistar rats were divided into MTA or FS groups and subdivided according to the period after pulpotomy procedure (24, 48 and 72 hours). Four teeth (sound and untreated) were used as controls. Histological sections were obtained and assessed through the descriptive analysis of morphological aspects of pulp tissue and the quantification of inflammatory cells, vascular density and interleukin-6 (IL-6) expression. Data were statistically analyzed (p<0.05).

RESULTS

The number of inflammatory cells was similar in both groups, being predominantly localized at the cervical radicular third. In the MTA group, increased inflammation was observed at 48 hours. Vascular density was similar in both groups and over time, being predominant in the medium radicular third. No correlation was found between the number of inflammatory cells and the vascular density. Pulp tissue was more organized in MTA-treated teeth. In both groups, a weak to moderate IL-6 expression was detected in odontoblasts and inflammatory cells. Comparing both groups, there was a greater IL-6 expression in the cervical radicular third of teeth treated with MTA at 24 hours and in the medium and apical thirds at 72 hours, while in the FS group a greater IL-6 expression was found in the apical third at 24 hours.

CONCLUSION

The MTA group presented better histological features and greater IL-6 expression than the FS group. However, no difference was observed between the groups regarding the inflammatory status and vascularization, suggesting the usefulness of FS as a low-cost alternative to MTA.

Effect of Er:YAG laser etching on topography, microstructure, compressive strength, and bond strength of a universal adhesive to calcium silicate cements

OBJECTIVE

To evaluate the effect of Er:YAG etching on topography, microstructure, compressive strength, and shear bond strength (SBS) of All-Bond Universal adhesive to mineral trioxide aggregate-Angelus (AMTA) and Biodentine (BD).

METHODS AND MATERIALS

Sixty cylindrical specimens of each cement (AMTA and BD) in five groups were prepared and stored for 72 h. The control groups were non-etched, and four other groups were acid-etched and laser-etched with a pulse energy of 60, 80, or 100 mJ, followed by compressive strength testing. Surface micromorphology and topography were evaluated. Similar groups were bonded using All-Bond Universal with self-etch and etch-and-rinse (acid-etch) approaches, and laser-etch 60, 80, and 100 mJ, and SBS was tested. Data were analyzed using two-way and one-way ANOVA and the Bonferroni post hoc tests (α = 0.05).

RESULTS

BD had a significantly higher compressive strength and SBS (except for laser-etch 100) compared to AMTA, regardless of the etching method (p < 0.001). Acid etching and laser etching 100 of both cements and laser etching 80 of BD alone produced a significantly lower compressive strength than that for the other groups. Contrary to BD, for AMTA, all the treatments significantly increased SBS compared to that of the self-etch group.

CONCLUSIONS

Etching of AMTA was needed for stronger bonding; laser etching with 60 or 80 mJ without compromising compressive strength was recommended. Etching not only did not improve bonding ability of BD, but it also negatively affected the strength of BD.

CLINICAL RELEVANCE

To achieve successful combined calcium silicate cement-resin material restoration, an adequate bond between the materials is mandatory. This might be provided with the ultramild adhesive through laser etching without compromising compressive strength, depending on cement composition and laser energy level used.

Effect of ultrasonic activation on dentinal tubule penetration of calcium silicate-based cements

This study investigated the dentinal tubule penetration of mineral trioxide aggregate (MTA), NeoMTA Plus and Biodentine placed by either manual condensation or ultrasonic activation in simulated open apex model. Standardized divergent open apex models were created using palatal roots of 60 human maxillary molars and divided into six groups according to the used cements and activation methods (n = 10): MTA-manual condensation, MTA-ultrasonic activation, NeoMTA Plus-manual condensation, NeoMTA Plus-ultrasonic activation, Biodentine-manual condensation, Biodentine-ultrasonic activation. For the measurement of penetration, the cements were mixed with 0.1% Rhodamin B and 6-mm apical portions of each root canal were obturated in an orthograde direction. The roots were embedded into acrylic blocks, and 1-mm-thick sections were obtained at 3 mm from the apex. Specimens were mounted onto glass slides and scanned under a confocal laser scanning microscope (CLSM) and stereomicroscope. Dentinal tubule penetration areas, depth and percentage were measured using LSM and ImageJ software. The data were analyzed using two-way analysis of variance (anova) with Bonferroni correction (α = 0.05). No correlation was found between stereomicroscope and CLSM analyses (p > .05). CLSM analysis showed no significant differences between MTA, NeoMTA Plus, and Biodentine groups when manual condensation was used (p > .05). Ultrasonic activation did not increase the tubular penetration of MTA, NeoMTA Plus or Biodentine as compared to manual condensation of each material (p > .05). MTA, NeoMTA Plus and Biodentine showed similar tubular penetration when manual condensation was used. Ultrasonic activation of these cements had no effect on tubular penetration of each material as compared to the manual condensation counterparts.

Nanostructured endodontic materials mixed with different radiocontrast agents-biocompatibility study

The aim of this study was to investigate the biocompatibility of nanostructured materials based on highly active calcium silicates mixed with different radiocontrast agents in comparison to MTA⁺ using in vitro and in vivo model. Morphology of materials' samples was analyzed using SEM while the phase compositions were identified by XRD. pH values of materials' suspensions were conducted by pH-meter. The cytotoxicity of materials' solutions was tested by MTT test (100, 50, 25 and 12.5 mg/ml). LDH and ³H-thymidine assay were utilized for biocompatibility investigations of materials' eluates (24 h, 7 day and 21 day). Eighteen Guinea pigs were used for intramuscular implantation, as teflon tubes with freshly prepared materials were placed into intramuscular pockets. All samples were composed of round and needle-like particles equally distributed with Ca/Si ratio ~2.7 at%, with the presence of hydrated calcium silicate phases. The pH values of ALBO-MPCA₁ and ALBO-MPCA₂ were high alkaline, while in case of MTA⁺ they were lower and continuously declined (p < 0.05). Investigated materials didn't exhibit dose-dependent effect on metabolic activity of L929 cells (p > 0.05). Significant differences in the percentage of cytotoxicity between diluted and undiluted extracts between all tested materials after 24 h and 7 day were noticed (p < 0.05). Increase in L929 cells proliferation was noticed in case of undiluted eluates of ALBO-MPCA₁ and ALBO-MPCA₂ after 7 day (p < 0.05). There were no statistically significant differences in the intensity of inflammatory response between investigated materials and control group after 60 day (p > 0.05). Evaluation of biocompatibility of both ALBO-MPCA₁ and ALBO-MPCA₂ indicate their potential clinical use.

Effect of reducing acid-etching duration time on compressive strength and bonding of a universal adhesive to calcium silicate cements

AIM

To assess the effect of acid-etching duration time on the compressive strength, microstructure and shear bond strength of All-Bond Universal adhesive to MTA-Angelus (AMTA), and Biodentine (BD).

METHODOLOGY

Forty-eight cylindrical specimens (4 mm in diameter, 6 mm in height) of AMTA in four groups and 48 specimens of BD in four groups (n = 12) were prepared and stored for 72 h. The control groups were unetched whilst the three experimental groups were acid-etched for 5, 10 and 15 s, respectively, followed by compressive strength testing. The effect of the various acid-etching times on surface micromorphology was evaluated under a scanning electron microscope. Similar groups were bonded using All-Bond Universal and Aelite Flo and shear bond strength was tested. Data were analysed using two-way ANOVA and Tukey tests.

RESULTS

10-s and 15-s acid-etching reduced the compressive strength of AMTA and BD (P < 0.001), while 5-s etching did not (P ≤ 0.86). In all the groups, BD had greater compressive strength compared to AMTA. Contrary to BD, the three etched AMTA groups had significantly higher shear bond strength compared to the control group (P < 0.001), with no significant differences between them. The etched groups of AMTA had shear bond strengths comparable to all the BD groups. Scanning electron microscope observations indicated variable surface morphologies such as remnant crystals and cracking/eroding in all our groups of AMTA; though these differences were less prominent for BD.

CONCLUSIONS

Shortening the acid-etching time to 5 s resulted in a beneficial effect in terms of resin bonding for AMTA while preventing the detrimental effect of 10-s and 15-s etching on the compressive strength of AMTA and BD. However, the three etching times had no effect on resin-BD bond.

Novel Fast-Setting Mineral Trioxide Aggregate: Its Formulation, Chemical-Physical Properties, and Cytocompatibility

One of the main drawbacks that limits the application of mineral trioxide aggregate (MTA) in dental field is its long setting time. Mineral trioxide aggregate with accelerated setting properties and excellent chemical-physical and biological properties is still required. In this study, an innovative mineral trioxide aggregate, which consists of calcium silicates, calcium aluminates, and zirconium oxide, was designed to obtain fast-setting property. The optimized formulation can achieve initial setting in 10 min and final setting in 15 min, which are much faster than commercial mineral trioxide aggregate. In addition, the optimized fast-setting MTA showed adequate radiopacity and good biocompatibility. The ion concentrations after storage in water for 1 day were 52.3 mg/L Ca, 67.7 mg/L Al, 48.8 mg/L Si, and 11.7 mg/L Mg. The hydration products of hardened cements were investigated by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared, showing the accelerated setting time was due to the formation of honeycomb-like calcium silicate hydrate gel. The novel MTA could be a promising material for dental applications.

Biocompatibility and biomineralization assessment of mineral trioxide aggregate flow

OBJECTIVE

Evaluate, in vivo, the biocompatibility via subcutaneous inflammatory tissue response and mineralization ability of the new MTA Flow compared to MTA Angelus and ProRoot MTA.

MATERIALS AND METHODS

Forty male Wistar rats were assigned and received subcutaneous polyethylene tube implants containing the test materials and a control group with empty tube (n = 10 animals/group). After days 7, 15, 30, and 60, the animals were euthanized and the polyethylene tubes were removed with the surrounding tissues. Inflammatory infiltrate and thickness of the fibrous capsule were histologically evaluated. Mineralization was analyzed by Von Kossa staining and under polarized light. Data were analyzed via Kruskal-Wallis and Dunn's test with a significance level of 5%.

RESULTS

MTA Angelus induced the mildest reaction after 7 (P > .05) and 15 days (P < .05) followed by MTA Flow, both cements achieving mild inflammatory reaction after 15 days. ProRoot MTA induced a severe inflammation on day 7 and was reducing after day 15 (P > .05). No difference was observed after days 30 or 60 (P > .05). Von Kossa staining and birefringent structures were positive to all materials.

CONCLUSIONS

At the end of the experiment, the novel MTA Flow showed biocompatibility and induced biomineralization in all time periods.

CLINICAL RELEVANCE

The final consistence obtained in MTA Flow may facilitate several procedures, indicating that the MTA Flow has a promising application in endodontics.

Systemic bone marker expression induced by grey and white mineral trioxide aggregate in normal and diabetic conditions

AIM

To investigate the relationship between diabetes mellitus and local/systemic effects of both grey and white mineral trioxide aggregate (MTA) Angelus on bone marker expression.

METHODOLOGY

Wistar rats were divided into two groups: healthy and diabetic (Alloxan induced), which were further divided into three subgroups (control, GMTA Angelus and WMTA Angelus). Polyethylene tubes filled with MTA materials or empty tubes were implanted in dorsal connective tissue. On days 7 and 30, blood samples were collected for calcium, phosphorus and ALP measurement. The animals were euthanized; implanted tubes were removed and processed for immunohistochemical analysis of osteocalcin (OCN) and osteopontin (OPN). Kruskal-Wallis followed by Dunn's multiple comparison test was performed for nonparametric data, and anova followed by Tukey's test for parametric data.

RESULTS

No difference in systemic serum calcium levels between both groups was observed. On day 7, serum phosphorus levels within the WMTA healthy group were higher than that of the diabetic group. On day 30, healthy rats exhibited lower phosphorus levels than diabetic ones. At both time points, the diabetic group was associated with more ALP activity than the healthy group. Immunohistochemical analyses of the healthy group revealed OCN- and OPN-positive cells in the presence of both MTA materials. However, under diabetic conditions, both OCN and OPN were absent.

CONCLUSION

Both MTA materials were associated with an increase in serum calcium, phosphorus and ALP, suggesting a potential systemic effect, along with triggered differentiation of OCN- and OPN-positive cells. Moreover, in diabetic conditions, an inhibitory effect on MTA-induced differentiation of OCN- and OPN-positive cells was detected.

Adaptation of mineral trioxide aggregate to dentine walls compared with other root-end filling materials: A systematic review

This systematic review analysed the literature comparing marginal adaptation of mineral trioxide aggregate (MTA) with other filling materials in root-end cavities. The PubMed, Ovid, Web of Science, SCOPUS, and Cochrane library databases were searched using appropriate keywords related to root-end filling materials and adaptation. Of 38 articles assessed, 20 met the inclusion criteria. No in vivo study was identified. In 10 studies, MTA gave the best marginal adaptation results, but no significant differences were found between MTA and any of the tested filling materials in seven studies. There was great variability in the study designs including analysed surface, unit of gap measurement and magnification amount during analysis. On the basis of available evidence, MTA presented good marginal adaptation to dentine walls. This review identified the need for the development of standardised methods to evaluate the adaptation property of root-end filling materials in ex vivo studies as well as in clinical studies evaluating outcome.

Mineral trioxide aggregate enriched with iron disulfide nanostructures: an evaluation of their physical and biological properties

The purpose of this study was to characterize mineral trioxide aggregates (MTA) enriched with iron disulfide (FeS₂ ) nanostructures at different concentrations, and to investigate their storage modulus, radiopacity, setting time, pH, cytotoxicity, and antimicrobial activity. Iron disulfide nanostructures [with particle size of 0.357 ± 0.156 μm (mean ± SD)] at weight ratios of 0.2, 0.4, 0.6, 0.8, and 1.0 wt% were added to white MTA (wMTA). The radiopacity, rheological properties, setting time, and pH, as well as the cytotoxicity (assessed using the MTT assay) and antibacterial activity (assessed using the broth microdilution test) were determined for MTA/FeS₂ nanostructures. The nanostructures did not modify the radiopacity values of wMTA (~6 mm of aluminium); however, they reduced the setting time from 18.2 ± 3.20 min to 13.7 ± 1.8 min, and the storage modulus was indicative of a good stiffness. Whereas the wMTA/FeS₂ nanostructures did not induce cytotoxicity when in contact with human pulp cells (HPCs) and human gingival fibroblasts (HGFs), they showed bacteriostatic activity against Staphylococcus aureus, Escherichia coli, and Enterococcus faecalis. Adding FeS₂ nanostructures to MTA might be an option for improving the root canal sealing and antibacterial effects of wMTA in endodontic treatments.

X-ray diffraction analysis of MTA mixed and placed with various techniques

OBJECTIVES

The aim of this study was to evaluate the effect of various mixing techniques as well as the effect of ultrasonic placement on hydration of mineral trioxide aggregate (MTA) using X-ray diffraction (XRD) analysis.

MATERIALS AND METHODS

One gram of ProRoot MTA and MTA Angelus powder was mixed with a 0.34-g of distilled water. Specimens were mixed either by mechanical mixing of capsules for 30 s at 4500 rpm or by manual mixing followed by application of a compaction pressure of 3.22 MPa for 1 min. The mixtures were transferred into the XRD sample holder with minimum pressure. Indirect ultrasonic activation was applied to half of the specimens. All specimens were incubated at 37 °C and 100% humidity for 4 days. Samples were analyzed by XRD. Phase identification was accomplished by use of search-match software utilizing International Centre for Diffraction Data (ICDD).

RESULTS

All specimens comprised tricalcium silicate, calcium carbonate, and bismuth oxide. A calcium hydroxide phase was formed in all ProRoot specimens whereas among MTA Angelus groups, it was found only in the sample mixed mechanically and placed by ultrasonication.

CONCLUSIONS

Mechanical mixing followed by ultrasonication did not confer a significant disadvantage in terms of hydration characteristics of MTA.

CLINICAL RELEVANCE

Clinicians vary in the way they mix and place MTA. These variations might affect their physical characteristics and clinical performance. For ProRoot MTA, the mixing and placement methods did not affect its rheological properties, whereas for MTA Angelus, mechanical mixing combined with ultrasonic placement enhanced the calcium hydroxide phase formation.

Effect of novel chelating agents on the push-out bond strength of calcium silicate cements to the simulated root-end cavities

To compare the effects of different chelating agents on the push-out bond strength of calcium silicate-based cements to the simulated root-end cavities. Root-end cavities were prepared on the roots of fifty extracted maxillary anterior teeth. The specimens were then randomly divided into 5 groups (n = 10) based on the final irrigation regimen: Group 1: 17% EDTA, Group 2: 7% maleic acid, Group 3: QMix, Group 4: 2.25% peracetic acid (PAA), Group 5: 0.9% saline. Then, the samples from each group were subdivided into two groups (n = 5) based on the apical filling material. In group 1, root-end cavities of all samples were filled with Biodentine and in group 2, with MTA. Each sample was horizontally sectioned to produce two discs of ∼1 mm thick per specimen. The maximum load required for the dislodgement of 100 retrofillings was recorded. The specimens were examined under scanning electron microscope after debonding to assess the type of bond failure. Data were statistically analyzed using Kruskal Wallis and Mann Whitney U tests. Irrigation with saline resulted in higher bond strength compared to the other irrigants in the retrograde cavities obturated with MTA or Biodentine (p < .05). In MTA group, there was no significant difference between the test irrigants (p > .05). EDTA and PAA groups showed higher dislodgement resistance values than the other test irrigants, when Biodentine was used as a filling. The type of irrigation solution influences the bond strength of the root-end fillings.

Bleaching of a Discolored Tooth with Retrieval of Remnants after Successful Regenerative Endodontics

INTRODUCTION

This report presents the retrieval of remnants from a discolored mandibular right second premolar (tooth #29) of a 17-year-old female after a successful regenerative endodontic procedure (REP).

METHODS

The REP was performed in October 2011. Coronal discoloration became of great concern to the patient at a review visit in 2016. A cone-beam computed tomographic scan was taken to investigate the formation of hard tissues within the root canal as well as a region of no calcified tissue formation. During internal bleaching of tooth #29, a black material with particulate inclusions was retrieved and examined histopathologically.

RESULTS

Five years after the REP, there was complete periapical healing, hard tissue formation within the root canal, and complete maturation of the root apex. A hard tissue bridge was noted at the cementoenamel junction when the pulp chamber of #29 was reaccessed. The remnants retrieved from the pulp chamber were confirmed to be partly mineral trioxide aggregate (MTA). A normal tooth color was achieved after 3 weeks of internal bleaching.

CONCLUSIONS

MTA remnants within the pulp chamber contributed to the tooth discoloration and appear to have obstructed hard tissue formation. A matrix of oxidized regenerated cellulose seems not to hinder tissue regeneration and is resorbed by these tissues. Other materials with color stability should be selected as coronal barriers for REPs to avoid a potential adverse effect of the MTA on the REP outcome and discoloration.

Sealer penetration and adaptation in root canals with the butterfly effect

The butterfly effect is a phenomenon seen in some roots and is related to density of dentinal tubules. The aim was to investigate penetration depth and adaptation quality of root canal sealers and ProRoot MTA into bucco-lingual and mesio-distal aspects of roots with and without the effect. One hundred and twenty teeth were decoronated at the cemento-enamel junction. Canals were prepared and assigned to obturation groups: gutta-percha with a sealer (AH Plus, EndoREZ, Kerr Pulp Canal Sealer, MTA Fillapex) or ProRoot MTA alone (each containing 10 butterfly and 10 non-butterfly roots). Root sectioning yielded coronal and middle samples. Confocal laser scanning and scanning electron microscopy were used to assess penetration and adaptation. Teeth with the effect had greater mean penetration bucco-lingually (766 μm) than mesio-distally (184 μm, P = 0.003). Coronal sections had greater penetration (430 μm) compared with middle (247 μm, P = 0.006). In conclusion, greater penetration in roots with the effect may improve treatment outcomes.

Current status of direct pulp-capping materials for permanent teeth

Direct pulp-capping is a method for treating exposed vital pulp with dental material to facilitate the formation of reparative dentin and to maintain vital pulp. Two types of pulp-capping materials, calcium hydroxide and mineral trioxide aggregate, have been most commonly used in clinics, and an adhesive resin has been considered a promising capping material. However, until now, there has been no comprehensive review of these materials. Therefore, in this paper, the composition, working mechanisms and clinical outcome of these types of pulp-capping materials are reviewed.

Biological response of commercially available different tricalcium silicate-based cements and pozzolan cement

This study evaluated four root repair materials for cytotoxicity and cell attachment in vitro. Cell viability was determined at 24 hr, 3 days and 7 days by using a 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay with material extracts. Cell adhesion was examined with a scanning electron microscope on the surface of materials at 24 and 48 hr. Angelus MTA displayed the lowest cell viabilities at all-day incubations. Endocem had high biocompatibility on the first day. After culturing for 3 days and 7 days, the cell viabilities of Biodentine, Endocem and MM-MTA had similar results, and their cell viability was significantly higher than that of Angelus. No definite relation was found between the incubation time and the relative cell viability in any group. In scanning electron micrographs, the cells were attached to the material surface for all materials, although the cells in the Biodentine group were attached better than the other groups on the second day. Cell viability and cell attachment was lower in the Angelus group. Endocem, Biodentine and MM-MTA were similar in biocompatibility and cytotoxicity.

Calcium silicate-based cements and functional impacts of various constituents

Calcium silicate-based cements have superior sealing ability, bioactivity, and marginal adaptation, which make them suitable for different dental treatment applications. However, they exhibit some drawbacks such as long setting time and poor handling characteristics. To overcome these limitations calcium silicates are engineered with various constituents to improve specific characteristics of the base material, and are the focus of this review. An electronic search of the PubMed, MEDLINE, and EMBASE via OVID databases using appropriate terms and keywords related to the use, application, and properties of calcium silicate-based cements was conducted. Two independent reviewers obtained and analyzed the full texts of the selected articles. Although the effects of various constituents and additives to the base Portland cement-like materials have been investigated, there is no one particular ingredient that stands out as being most important. Applying nanotechnology and new synthesis methods for powders most positively affected the cement properties.

Influence of powder composition and morphology on penetration of Gray and White ProRoot mineral trioxide aggregate and calcium hydroxide into dentin tubules

This study examined the influence of powder composition and morphology on the penetration of Gray and White ProRoot mineral trioxide aggregate (GMTA, WMTA) and calcium hydroxide (CH) into open dentin tubules. GMTA, WMTA, and CH particle dimensions were analyzed by flow particle image analysis (FPIA). Penetration of open dentin tubules into dentin discs was studied by scanning electron microscopy. Five samples of each material were randomly selected and prepared for this study. The GMTA averages for length (μm), width (μm), perimeter (μm), and aspect ratio were 1.94 ± 1.65, 1.43 ± 1.19, 5.61 ± 4.27, and 0.76 ± 0.14, respectively. Corresponding averages for WMTA were 2.04 ± 1.87, 1.49 ± 1.33, 5.88 ± 4.81, and 0.76 ± 0.14, and for CH were 2.26 ± 1.99, 1.62 ± 1.46, 6.70 ± 5.60, and 0.74 ± 0.15, respectively. The rank order of the averages for particle length, width and perimeter from the largest to the smallest material was CH > WMTA > GMTA. The rank order of the averaged aspect ratios was GMTA > WMTA > CH. SEM showed that all three materials, when deposited and agitated on dentin discs, penetrated the open dentin tubules. Tubule occlusion occurred as particle surface concentrations increased. Significant differences in particle length, width, perimeter, and aspect ratio were observed for GMTA, WMTA, and CH (P < 0.0001 in all cases). All particle types penetrated into open tubules when agitated on dentin discs; all tubules were eventually occluded as particle concentrations grew. (J Oral Sci 56, 287-293, 2014).

Evaluation of the bond strength of different adhesive agents to a resin-modified calcium silicate material (TheraCal LC)

This study evaluated the bond strength of different adhesive agents to TheraCal LC and mineral trioxide aggregate (MTA) and examined the morphologic changes of these materials with different surface treatments. A total of 120 specimens, 60 of MTA Angelus (AMTA), and 60 of TheraCal LC, were prepared and divided into six subgroups according to the adhesive agent used; these agents included Scotchbond Multipurpose, Clearfil SE Bond, Clearfil Protect Bond, Clearfil S³ Bond, OptiBond All-in-One, and G-aenial Bond. After application of adhesive agents, Filtek Z250 composite resin was placed onto the specimens. Shear bond strengths were measured using a universal testing machine, followed by examination of the fractured surfaces. The surface changes of the specimens were observed using scanning electron microscopy. Data were compared by two-way analysis of variance. Although no significant differences were found among the bond strengths of different adhesives to AMTA (p = 0.69), a significant difference was found in terms of bond strengths of different adhesives to the TheraCal LC surface (p < 0.001). The total-etch adhesive system more strongly bonded to TheraCal LC compared to the bond with other adhesives. TheraCal LC bonded significantly more strongly than AMTA regardless of the adhesive agents tested. Resin-modified calcium silicate showed higher bond strength than AMTA in terms of the composite bond to these materials with different bonding systems. On the other hand, the highest shear bond-strength values were found for composite bonds with the combination of TheraCal LC and the total-etch adhesive system. SCANNING 38:403-411, 2016. © 2015 Wiley Periodicals, Inc.

Deconvolution of the particle size distribution of ProRoot MTA and MTA Angelus

Objective Mineral trioxide aggregate (MTA) cements contain two types of particles, namely Portland cement (PC) (nominally 80% w/w) and bismuth oxide (BO) (20%). This study aims to determine the particle size distribution (PSD) of PC and BO found in MTA.

Materials and methods The PSDs of ProRoot MTA (MTA-P) and MTA Angelus (MTA-A) powder were determined using laser diffraction, and compared to samples of PC (at three different particle sizes) and BO. The non-linear least squares method was used to deconvolute the PSDs into the constituents. MTA-P and MTA-A powders were also assessed with scanning electron microscopy.

Results BO showed a near Gaussian distribution for particle size, with a mode distribution peak at 10.48 μm. PC samples milled to differing degrees of fineness had mode distribution peaks from 19.31 down to 4.88 μm. MTA-P had a complex PSD composed of both fine and large PC particles, with BO at an intermediate size, whereas MTA-A had only small BO particles and large PC particles.

Conclusions The PSD of MTA cement products is bimodal or more complex, which has implications for understanding how particle size influences the overall properties of the material. Smaller particles may be reactive PC or unreactive radiopaque agent. Manufacturers should disclose particle size information for PC and radiopaque agents to prevent simplistic conclusions being drawn from statements of average particle size for MTA materials.

Dynamic intratubular biomineralization following root canal obturation with pozzolan-based mineral trioxide aggregate sealer cement

The application of mineral trioxide aggregates (MTA) cement during the root canal obturation is gaining concern due to its bioactive characteristic to form an apatite in dentinal tubules. In this regard, this study was to assess the biomineralization of dentinal tubules following root canal obturation by using pozzolan-based (Pz-) MTA sealer cement (EndoSeal MTA, Maruchi). Sixty curved roots (mesiobuccal, distobuccal) from human maxillary molars were instrumented and prepared for root canal obturation. The canals were obturated with gutta-percha (GP) and Pz-MTA sealer by using continuous wave of condensation technique. Canals obturated solely with ProRoot MTA (Dentsply Tulsa Dental) or Pz-MTA sealer were used for comparison. In order to evaluate the biomineralization ability under different conditions, the PBS pretreatment before the root canal obturation was performed in each additional samples. At dentin-material interfaces, the extension of intratubular biomineralization was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy. When the root canal was obturated with GP and Pz-MTA sealer, enhanced biomineralization of the dentinal tubules beyond the penetrated sealer tag was confirmed under the SEM observation (p < 0.05). Mineralized apatite structures (calcium/phosphorous ratio, 1.45-1.89) connecting its way through the dentinal tubules were detected at 350-400 μm from the tubule orifice, and the pre-crystallization seeds were also observed along the intra- and/or inter-tubular collagen fiber. Intratubular biomineralization depth was significantly enhanced in all PBS pretreated canals (p < 0.05). Pz-MTA cement can be used as a promising bioactive root canal sealer to enhance biomineralization of dentinal tubules under controlled environment.

Similar sealability between bioceramic putty ready-to-use repair cement and white MTA

This study was designed to assess the ability to prevent glucose penetration of a bioceramic putty ready-to-use repair cement comparing to white mineral trioxide aggregate (WMTA). After root canal instrumentation, the apical 3 mm of maxillary incisors were resected and root-end cavities with depth of 3 mm were prepared with ultrasound and filled with the tested materials (15 roots per group). All roots were mounted in a double chamber system to assess glucose penetration using 15 psi pressure application. After 1 h, glucose concentrations in the lower chamber were measured following an enzymatic reaction. Four roots were used as controls. The Mann-Whitney test verified differences in glucose leakage between groups and the Tukey's test was used for multiple comparisons. Significance level was set at 5%. There was no significant difference in glucose leakage between iRoot BP Plus and White MTA groups. iRoot BP Plus had a similar ability to that of white MTA in preventing glucose leakage as a root-end filling material.