Elemental Analysis of Crystal Precipitate from Gray and White MTA

Comparative evaluation of bioactivity of MTA plus and MTA plus chitosan conjugate in phosphate buffer saline an invitro study

Background and Objective

Various materials like MTA, Biodentine etc have been used for the regeneration of lost dental tissues. Still, the quest for newer materials to enhance the bioactivity of the existing materials continues. Hence this study aims at the evaluation of bioactivity of MTA Plus when conjugated with Chitosan in phosphate buffer saline.

Methodology

Materials used were MTA Plus (Group 1), MTA Plus and chitosan conjugate(Group 2). The materials were mixed and placed in phosphate buffer saline. Bioactivity of Group 1 and Group 2 materials were assessed at 7 days and 28 day's time intervals using SEM-EDX analysis.

Results

SEM analysis of group 1 revealed a compact and agglomerate lath-like appearance with uniform particle size. SEM analysis of group 2 reveals acicular and lath-like appearance of the precipitate on the material surface. EDX analysis of the freshly prepared materials gave the qualitative semiquantitative elemental composition on the material surfaces after immersion in PBS for 7 and 28 days.

Conclusion

MTA Plus Chitosan conjugate had greater potential to form apatite crystals on its surface. Hence, Chitosan can be used as a vehicle for the currently available materials to enhance the bioactivity and fasten the healing process.

Biological and chemical properties of five mineral oxides and of mineral trioxide aggregate repair high plasticity: an in vitro study

Calcium silicate-based cements have diverse applications in endodontics. This study aimed to evaluate the antibiofilm action, biocompatibility, morphological structure, chemical composition and radiopacity of Five Mineral Oxides (5MO), Mineral Trioxide Aggregate Repair High Plasticity (MTA Repair HP), and Mineral Trioxide Aggregate (MTA) cements. MTT analysis was used to test the antibiofilm action of these cements against five anaerobic microorganisms, and test their biocompatibility with mouse macrophage (RAW 264.7) and osteoblasts (MG-63) cultures. Their morphological structure and chemical composition were evaluated by scanning electron microscopy (SEM) coupled to energy dispersion X-ray spectroscopy (EDX), and the phase analysis was performed by X-ray diffraction (XRD). Conventional radiography was used to assess the radiopacity of the cements. 5MO, MTA Repair HP and MTA were effective against Porphyromonas gingivalis, Parvimonas micra, Fusobacterium nucleatum and Prevotella intermedia, they were biocompatible with macrophages and osteoblasts after 5 min of contact, and they had adequate radiopacity to be used clinically. Bismuth oxide (Bi2O3) is used as a radiopacifier in MTA and 5MO, and calcium tungstate, in MTA Repair HP. Titanium dioxide (TiO₂) (ANATASE) is responsible for the antimicrobial action and biocompatibility of 5MO.

Push-Out Bond Strength and Dentinal Penetration of a Novel Herbal-Based Pulp Capping Agent: An In vitro Study

Background: Pulp capping agents should have proper sealing effect to enhance dental pulp tissue healing. Aim: The purpose of this study was to compare the effectiveness of grape seed extract (GSE) and Mineral trioxide aggregate (MTA) to penetrate to dentin and their push-out bond strength at two time intervals (1 and 3 months) when used as pulp capping agents either singly or combined to each other. Materials and Methods: This study was conducted on 120 human single-rooted anterior teeth. Sixty dentin discs were randomly divided into three groups (n=20) based on the material used; MTA, GSE, and a combination of MTA and GSE. A universal testing machine was used to determine the push-out bond strength for one and three months. At the same time intervals, extra 60 teeth with the same groups were utilized to quantify the degree of capping material penetration within the dentinal tubules using scanning electron microscopy (SEM). ANOVA with multiple comparison Post hoc test was used to evaluate the data where the p value was < 0.05. Results: MTA had the highest push-out bond strength and penetration depth measurement into dentinal tubules at one month, followed by MTA combined with GSE, while GSE had the lowest push-out bond strength and penetration depth measurement. Nevertheless, GSE had the greatest values in both tests at 3 months, followed by MTA, while MTA coupled with GSE had the lowest value in both tests. Conclusion: Push out bond strength and dentinal penetration depth were improved with time except for the MTA group testing its dentinal penetration depth. GSE shows good push out bond strength and dentinal penetration depth.

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.

A Scanning Electron Microscopic Study on Effect of Blood and Artificial Salivary Contamination on Marginal Adaptation of Mineral Trioxide Aggregate, When Used as a Retrograde Filling Material: An In Vitro Study

Aim and objective

The present study was conducted to evaluate the marginal adaptability of mineral trioxide aggregate (MTA) as a root-end filling material when manipulated using two different IV fluids intended for pediatric usage; in the presence of blood and salivary contamination.

Materials and methods

Sixty single-rooted teeth were selected. Conventional endodontic root canal preparation was performed on all specimens followed by root-end resection and retrograde cavity preparation. The roots were randomly divided into two groups (n = 30). In the specimens of group I, fresh blood was used as a contaminant and in group II artificial saliva was used as a contaminant. In both groups, MTA (e-MTA, Kids-e-Dental®) manipulated using either Ringer's lactate IV fluid (n = 15) or Tetraspan IV fluid (n = 15) was used for root-end filling in blood or artificial saliva-coated retrocavities. Furthermore, these roots were placed in beakers pooled with fresh phlebotomized blood or artificial saliva. After incubating for 48 hours, the roots were divided longitudinally to expose the retrofilled cavities and were then sputter-coated with gold-platinum dust. To assess the marginal adaptation of MTA to radicular dentin "maximum gap width" and "gap perimeter" were measured in images obtained from scanning electron microscopy of root specimens. SPSS 21 was employed for statistical analysis at (p < 0.05). Mann-Whitney U test and ANOVA were used for analyzing the data obtained.

Results

The gap width was more among samples exposed to blood (p < 0.05) than artificial saliva. No significant difference was reported in the gap perimeter when cavities were filled with MTA mixed with either IV fluids (p > 0.05).

Conclusion

Exposure to blood during setting had a negative effect on gap width when retrocavities were filled with MTA using Tetraspan. No effect was seen on the arch perimeter in retrocavities filled with MTA mixed with Ringer's lactate or Tetraspan.

Clinical significance

For avoiding failure, it is critical to select a biocompatible root-end filling material with high sealing ability. Hence, by doing the same, the clinical situation can be simulated.

How to cite this article

Mody A, Arora R, Chauhan P, et al. A Scanning Electron Microscopic Study on Effect of Blood and Artificial Salivary Contamination on Marginal Adaptation of Mineral Trioxide Aggregate, When Used as a Retrograde Filling Material: An In Vitro Study. Int J Clin Pediatr Dent 2021;14(5):674-680.

Fabrication and Characterization of a Nanofast Cement for Dental Restorations

This study was aimed at fabricating and evaluating the physical and bioproperties of nanofast cement (NFC) as a replacement of the MTA. The cement particles were decreased in nanoscale, and zirconium oxide was used as a radiopacifier. The setting time and radiopacity were investigated according to ISO recommendations. Analysis of color, bioactivity, and cytotoxicity was performed using spectroscopy, simulated body fluid (SBF), and MTT assay. The setting time of cement pastes significantly dropped from 65 to 15 min when the particle sizes decreased from 2723 nm to 322 nm. Nanoparticles provide large surface areas and nucleation sites and thereby a higher hydration rate, so they reduced the setting time. Based on the resulting spectroscopy, the specimens did not exhibit clinically noticeable discoloration. Resistance to discoloration may be due to the resistance of zirconium oxide to decomposition. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and infrared spectroscopy (FTIR) examinations of the immersed SBF samples showed apatite formation that was a reason for its suitable bioactivity. The results of cell culture revealed that NFC is nontoxic. This study showed that NFC was more beneficial than MTA in dental restorations.

Tissue reaction to novel customized calcium silicate cement based dental implants. A pilot study in the dog

OBJECTIVES

The purpose of this study was to determine the level of periodontal tissue regeneration in a canine model following post-extraction placement of an implant molded from a composite material made from extracted tooth dentin and a calcium silicate cement (CSC) material. The investigation used autologous dentin in conjunction with a CSC material to form a composite implant designed for immediate tooth replacement.

METHODS

Two (2) beagles had a periodontal and radiographic examination performed to rule out any pre-treatment inflammation, significant periodontal disease, or mobility. Then, ination eleven (11) teeth were extracted and polyvinyl siloxane molds were made to fabricate three different types of implants: Particulate Implant (Test Group 1, n = 4), Shell Implant Alone (Test Group 2, n = 2), Shell Implant with Emdogain® (Test Group 3, n = 3). Teeth in the control group were extracted, scaled (n = 2), and then re-implanted into their respective fresh extraction sockets. At 4 weeks, a clinical, radiographic, and histologic assessment was performed.

RESULTS

Clinical evaluation revealed no mobility in any of the test or control implants and no radiographic evidence of significant bone loss or active disease. Based on the MicroCT analysis, direct bone to implant contact was observed in some areas with an apparent periodontal ligament space. Implant-related inflammation, on average, was similar among all groups, with low numbers of infiltrates. Implant-related inflammatory reaction was generally minimal and not interpreted to be adverse.

CONCLUSION

The proposed novel composite materials revealed that not only do these materials demonstrate high biocompatibility, but also their successful integration in the alveolus is likely secondary to a partial ligamentous attachment. The current investigation may lead to the use of calcium silicate-based materials as custom dental implants. Further research on this novel composite's biomechanical properties is necessary to develop the optimal material composition for use as a load-bearing dental implant.

Push-Out Bond Strength, Characterization, and Ion Release of Premixed and Powder-Liquid Bioceramic Sealers with or without Gutta-Percha

OBJECTIVE

To evaluate the push-out bond strength of premixed and powder-liquid bioceramic sealers with or without gutta-percha (GP) cone.

MATERIALS AND METHODS

Radicular dentin samples were prepared from 80 single-rooted human teeth. After root canal preparation using ProTaper® and irrigation with NaOCl and EDTA, teeth were divided according to the root canal sealer (n = 20): AH Plus®, EndoSequence® BC Sealer™, ProRoot® Endo Sealer, and BioRoot™ RCS. Samples were randomly divided into two subgroups (n = 10): GP-S: root canal filling using the single-cone technique, or S: filling with only sealer. Specimens were kept at 37°C and 100% humidity in calcium-free PBS for 30 days. The push-out bond strength was measured in MPa. Fractured specimens were observed at 25x to evaluate the type of failure. pH and calcium ion release were measured at different experimental periods. Raman and SEM-EDAX analyses were performed for root canal sealers. Data were analysed using three-way analysis of variance (ANOVA) and post hoc Tukey test at a significance of P < 0.05.

RESULTS

Push-out bond strength was greater for samples obturated with only sealers (S) than samples obturated with the single-cone technique (GP-S) (P < 0.05). BioRoot™ RCS had greater bond strength than EndoSequence® BC Sealer™. Adhesive failures between cement and gutta-percha cone (87.5%) were predominant in the GP-S. Cohesive failures were predominant for S (80%). BioRoot™ RCS and ProRoot® ES presented higher alkalinization potential than the premixed sealer (EndoSequence® BC Sealer™). Powder-liquid bioceramic sealers (BioRoot™ RCS and ProRoot® ES) released the highest cumulative amount of calcium (28.46 mg/L and 20.05 mg/L).

CONCLUSION

Push-out test without gutta-percha cone presents higher bond strength for bioceramic sealers. Powder-liquid calcium silicate-based sealers present greater bioactivity related to alkalinization potential and calcium ion release.

Biocompatibility and bioactive potential of the NeoMTA Plus endodontic bioceramic-based sealer

Objectives

This study evaluated the biocompatibility and bioactive potential of NeoMTA Plus mixed as a root canal sealer in comparison with MTA Fillapex.

Materials and Methods

Polyethylene tubes filled with NeoMTA Plus (n = 20), MTA Fillapex (n = 20), or nothing (control group, CG; n = 20) were inserted into the connective tissue in the dorsal subcutaneous layer of rats. After 7, 15, 30 and 60 days, the specimens were processed for paraffin embedding. The capsule thickness, collagen content, and number of inflammatory cells (ICs) and interleukin-6 (IL-6) immunolabeled cells were measured. von Kossa-positive structures were evaluated and unstained sections were analyzed under polarized light. Two-way analysis of variance was performed, followed by the post hoc Tukey test (p ≤ 0.05).

Results

At 7 days, the capsules around NeoMTA Plus and MTA Fillapex had more ICs and IL-6-immunostained cells than the CG. However, at 60 days, there was no significant difference in the IC number between NeoMTA Plus and the CG (p = 0.1137) or the MTA Fillapex group (p = 0.4062), although a greater number of IL-6-immunostained cells was observed in the MTA Fillapex group (p = 0.0353). From 7 to 60 days, the capsule thickness of the NeoMTA Plus and MTA Fillapex specimens significantly decreased, concomitantly with an increase in the collagen content. The capsules around root canal sealers showed positivity to the von Kossa stain and birefringent structures.

Conclusions

The NeoMTA Plus root canal sealer is biocompatible and exhibits bioactive potential.

Influence of blood contamination on the bond strength and biointeractivity of Biodentine used as root-end filling

Aim

To evaluate the influence of blood contamination on the bond strength and apatite forming ability of Biodentine used as root-end filling material.

Methodology

Eighty (n = 80) extracted single-rooted, sound human maxillary anterior teeth were prepared and obturated. Then, the roots were resected, retrograde cavities were prepared and Biodentine was inserted as the root-end filling material. Teeth were then randomly divided into 2 equal groups (n = 40) according to the setting environment of Biodentine i.e., group A where setting took place in human blood and group B where setting took place in deionized water (control group). Teeth were incubated at 37  °C for 45 min to ensure complete setting. Root discs with the filling material in their core were prepared. Push-out bond strength test was performed using a universal testing machine and failure mode was examined. Both groups were aged in HBSS for 30 days. Apatite nucleation was evaluated at one-day, 7-days, and 30-days interval using SEM for morphological analysis and EDX for elemental analysis. Calculation of the Ca/P ratios was performed in addition to XRD for crystal phase analysis.

Results

Blood contamination (group A) resulted in significant reduction of bond strength values. It also affected the amount of apatite deposition on the material surface and interfacial spaces with higher Ca/P ratios than that of the normal stoichiometric hydroxyapatite.

Conclusions

Blood contamination during setting of Biodentine had a detrimental effect on the bond strength and reduced the nucleation of apatite in comparison to non-contaminated group.

Interface between calcium silicate cement and adhesive systems according to adhesive families and cement maturation

Objectives

This study aimed to evaluate the interface between a calcium silicate cement (CSC), Biodentine and dental adhesives in terms of sealing ability.

Materials and Methods

Microleakage test: 160 standardized class II cavities were prepared on 80 extracted human molars. The cavities were filled with Biodentine and then divided into 2 experimental groups according to the time of restoration: composite resin obturation 15 minutes after Biodentine handling (D0); restoration after 7 days (D7). Each group was then divided into 8 subgroups (n = 5) according to the adhesive system used: etch-and-rinse adhesive (Prime & Bond); self-etch adhesive 2 steps (Optibond XTR and Clearfil SE Bond); self-etch adhesive 1 step (Xeno III, G-aenial Bond, and Clearfil Tri-S Bond); and universal used as etch-and-rinse or self-etch (ScotchBond Universal ER or SE). After thermocycling, the teeth were immersed in a silver nitrate solution, stained, longitudinally sectioned, and the Biodentine/adhesive percolation was quantified. Scanning electron microscopic observations: Biodentine/adhesive interfaces were observed.

Results

A tendency towards less microleakage was observed when Biodentine was etched (2.47%) and when restorations were done without delay (D0: 4.31%, D7: 6.78%), but this was not significant. The adhesives containing 10-methacryloyloxydecyl dihydrogen phosphate monomer showed the most stable results at both times studied. All Biodentine/adhesive interfaces were homogeneous and regular.

Conclusions

The good sealing of the CSC/adhesive interface is not a function of the system adhesive family used or the cement maturation before restoration. Biodentine can be used as a dentine substitute.

Fracture resistance of human roots filled with mineral trioxide aggregate mixed with phosphate-buffered saline, with and without calcium hydroxide pre-medication

AIM

To compare the fracture strength of extracted human roots with apical plugs of mineral trioxide aggregate (MTA) mixed with either Ca- and Mg-free phosphate-buffered saline (PBS) or water, with and without calcium hydroxide (CH) canal pre-medication.

METHODOLOGY

A total of 180 single-rooted human teeth were prepared to resemble immature roots and divided into groups (n = 20). The negative control received canal irrigation only, and the positive control received intracanal treatment with CH for either two or twelve weeks. MTA mixed with water was used in Group 1: (i) without CH pre-medication - MTA(W); (ii) after 2 weeks CH pre-medication - 2/52CH + MTA(W); and (iii) after 12-week CH pre-medication - 12/52 CH + MTA(W). MTA mixed with PBS was used in Group 2: (i) without CH pre-medication - MTA(PBS); (ii) after 2-week CH pre-medication - 2/52CH + MTA(PBS); and (iii) after 12-week CH pre-medication - 12/52 CH + MTA(PBS). A compressive force was applied to each root until the point of fracture. The results were analysed by the Kruskal-Wallis and Dunn's multiple comparisons tests (P < 0.05).

RESULTS

There was no significant difference between groups MTA(W), MTA(PBS) and 2/52CH + MTA(PBS), and all three groups were significantly (P < 0.01, P < 0.05 and P < 0.05, respectively) more resistant to fracture than the negative control. Within Group 1, the samples that received two- (P < 0.01) and twelve-week (P < 0.001) CH pre-treatment were more prone to fracture than those which did not. No difference was found amongst the control groups. The roots of the MTA(PBS) group had a higher dependability (P < 0.05) than the MTA(W) group when compared by the Weibull modulus. The difference was also present when a 2-week CH pre-medication was used.

CONCLUSIONS

Mineral trioxide aggregate mixed with Ca- and Mg-free phosphate-buffered saline had a significant strengthening effect on the fracture resistance of structurally weak roots, even when short-term calcium hydroxide pre-medication had been used. MTA mixed with water lost its strengthening effect on human roots when 2- or 12-week CH pre-treatment had been used. Use of CH dressing for up to 12 weeks had no negative effect on fracture resistance of human roots.

Characterization of Living Dental Pulp Cells in Direct Contact with Mineral Trioxide Aggregate

Mineral trioxide aggregate (MTA) was introduced as a material for dental endodontic regenerative therapy. Here, we show the dynamics of living dental pulp cells in direct contact with an MTA disk. A red fluorescence protein (DsRed) was introduced into immortalized porcine dental pulp cells (PPU7) and cloned. DsRed-PPU7 cells were cultured on the MTA disk and cell proliferation, chemotaxis, the effects of growth factors and the gene expression of cells were investigated at the biological, histomorphological and genetic cell levels. Mineralized precipitates formed in the DsRed-PPU7 cells were characterized with crystal structural analysis. DsRed-PPU7 cells proliferated in the central part of the MTA disk until Day 6 and displayed a tendency to move to the outer circumference. Both transforming growth factor beta and bone morphogenetic protein promoted the proliferation and movement of DsRed-PPU7 cells and also enhanced the expression levels of odontoblastic gene differentiation markers. Mineralized precipitates formed in DsRed-PPU7 were composed of calcium and phosphate but its crystals were different in each position. Our investigation showed that DsRed-PPU7 cells in direct contact with the MTA disk could differentiate into odontoblasts by controlling cell–cell and cell–substrate interactions depending on cell adhesion and the surrounding environment of the MTA.

Bioactivity and Physicochemical Properties of Three Calcium Silicate-Based Cements: An In Vitro Study

Objective

This study evaluated the bioactivity and physicochemical properties of three commercial calcium silicate-based endodontic materials (MTA, EndoSequence Root Repair Material putty, and Biodentine™). Material and Methods. Horizontal sections of 3 mm thickness from 18 root canals of human teeth were subjected to biomechanical preparation with WaveOne Gold large rotary instruments. The twelve specimens were filled with three tested materials (MM-MTA, EndoSequence Root Repair Material putty, and Biodentine™) and immersed in phosphate-buffered saline for 7 and 30 days. After this period of time, each specimen of each material was processed for morphological observation, surface precipitates, and interfacial dentin using SEM. In addition, the surface morphology of the set materials, without soaking in phosphate-buffered solution after one day and after 28 days stored in phosphate-buffered saline, was evaluated using SEM; also, the pH of the soaking water and the amount of calcium ions released from the test materials were measured by using an inductively coupled plasma-optical emission spectroscopy test. Data obtained were analyzed using one-way analysis of variance and Tukey's honest significant difference test with a significance level of 5%.

Result

The formation of precipitates was observed on the surfaces of all materials at 1 week and increased substantially over time. Interfacial layers in some areas of the dentin-cement interface were found from one week of immersion. All the analyzed materials showed alkaline pH and capacity to release calcium ions; however, the concentrations of released calcium ions were significantly more in Biodentine and ESRRM putty than MM-MTA (P < 0.05). ESRRM putty maintained a pH of around 11 after 28 days.

Conclusion

Compared with MM-MTA, Biodentine and ESRRM putty showed significantly more calcium ion release. However, exposure of three tested cements to phosphate-buffered solution resulted in precipitation of apatite crystalline structures over both cement and dentin that increased over time. This suggests that the tested materials are bioactive.

Effect of elastin-like polypeptide incorporation on the adhesion maturation of mineral trioxide aggregates

The aim of this study was to investigate the effects of the incorporation of elastin-like polypeptide (ELP) on the adhesion maturation of mineral trioxide aggregates (MTA). Two types of ELPs (V125 and V125E8) were genetically synthesized. V125 consisted of 125 repeating pentapeptides (Val-Pro-Gly-Xaa-Gly) and V125E8 was functionalized with octaglutamic acid in the C-terminus of V125; both were diluted to 10 wt% in solution. Three 1.5 mm diameter holes in dentin discs were filled with MTA mixed with either a solution of ELP or deionized water. Push-out bond strength tests were performed following storage in simulated body fluid (SBF) for 1, 2, 4, and 8 weeks (n = 12). The interface between dentin and MTA was observed via scanning electron microscopy (SEM). The maturation of MTA was evaluated with a stereoscopic microscope and SEM. The incorporation of a specific ELP (V125E8) significantly increased the bond strength of MTA to dentin with regard to every maturation period (p < 0.05). The bond strength of MTA also significantly increased with a longer maturation time irrespective of ELP incorporation (p < 0.05). V125E8-incorporated MTA exhibited a more intimate interface with dentin compared to the other groups. More spindle-shaped crystal structures and thicker crystals were observed in all MTA mixtures as the storage duration increased even though V125E8 exhibited fewer crystal structures on the surface. Within the limitations of this study, the incorporation of V125E8 increased the adhesive properties of MTA and the maturation of MTA occurred regardless of ELP incorporation.

Non-Collagenous Dentin Protein Binding Sites Control Mineral Formation during the Biomineralisation Process in Radicular Dentin

The biomineralisation of radicular dentin involves complex molecular signalling. Providing evidence of protein binding sites for calcium ions and mineral precipitation is essential for a better understanding of the remineralisation process. This study aimed to evaluate the functional relationship of metalloproteinases (MMPs) and non-collagenous proteins (NCPs) with mineral initiation and maturation during the biomineralisation of radicular dentin. A standardized demineralisation procedure was performed to radicular dentin slices. Samples were remineralised in a PBS-bioactive material system for different periods of time. Assessments of ion exchange, Raman analysis, and energy dispersive X-ray analysis (EDAX) with a scanning electron microscope (SEM) were used to evaluate the remineralisation process. Immunohistochemistry and zymography were performed to analyse NCPs and MMPs expression. SEM evaluation showed that the mineral nucleation and growth occurs, exclusively, on the demineralised radicular dentin surface. Raman analysis of remineralised dentin showed intense peaks at 955 and 1063 cm⁻¹, which can be attributed to carbonate apatite formation. Immunohistochemistry of demineralised samples revealed the presence of DMP1-CT, mainly in intratubular dentin, whereas DSPP in intratubular and intertubular dentin. DMP1-CT and DSPP binding sites control carbonate apatite nucleation and maturation guiding the remineralisation of radicular dentin.

Efficacy of Mineral Trioxide Aggregate and Biodentine as Apical Barriers in Immature Permanent Teeth: A Microbiological Study

Aim

To compare the bacterial leakage of mineral trioxide aggregate (MTA) and biodentine when used as an apical plug in immature permanent teeth.

Materials and methods

It was a randomized double-blind in vitro study. A total of 60 teeth were divided into 2 groups of MTA and biodentine, which were further divided into 2 subgroups (n = 30) each based on the apical plug thickness of 2 and 4 mm. The teeth were cleaned and shaped; root-end resection and canal preparation were done. Mineral trioxide aggregate and biodentine were mixed and filled as apical plugs of 2 or 4 mm thickness. Enterococcus faecalis was used to assess the bacterial leakage of the filled samples.

Statistical analysis

The comparison between the two groups was done by Chi-square test for categorical data. All p values <0.05 were considered as statistically significant.

Results

A 4 mm apical plug of biodentine showed the least amount of bacterial leakage followed by 2 mm MTA and 4 mm MTA. A 2 mm apical plug of biodentine showed the maximum bacterial leakage. But this was not statistically significant over a period of 3 months. There was a statistically significant difference (p value = 0.042) among the total number of samples that leaked in the 2 and 4 mm biodentine group.

Conclusion

Mineral trioxide aggregate and biodentine had a similar apical sealing ability. The apical sealing ability of biodentine at 4 mm thickness was greater than 2 mm thickness.

Clinical significance

The apical leakage of the materials used in apexification is one of the main causes of endodontic failures in immature necrotic teeth. Materials like MTA and biodentine have overcome various drawbacks of calcium hydroxide as apexification material. The thickness of the apical plug plays an important role in preventing any microorganism from entering the periapical area, hence maintaining an adequate seal.

How to cite this article

Abbas A, Kethineni B, Puppala R, et al. Efficacy of MTA and Biodentine as Apical Barriers in Immature Permanent Teeth: A Microbiological Study. Int J Clin Pediatr Dent 2020;13(6):656-662.

Bioactive Glass-Based Endodontic Sealer as a Promising Root Canal Filling Material without Semisolid Core Materials

Endodontic treatment for a tooth with damaged dental pulp aims to both prevent and cure apical periodontitis. If the tooth is re-infected as a result of a poorly obturated root canal, periapical periodontitis may set-in due to invading bacteria. To both avoid any re-infection and improve the success rate of endodontic retreatment, a treated root canal should be three-dimensionally obturated with a biocompatible filling material. Recently, bioactive glass, one of the bioceramics, is focused on the research area of biocompatible biomaterials for endodontics. Root canal sealers derived from bioactive glass-based have been developed and applied in clinical endodontic treatments. However, at present, there is little evidence about the patient outcomes, sealing mechanism, sealing ability, and removability of the sealers. Herein, we have developed a bioactive glass-based root canal sealer and provided evidence concerning its physicochemical properties, biocompatibility, sealing ability, and removability. We also review the classification of bioceramics and characteristics of bioactive glass. Additionally, we describe the application of bioactive glass to facilitate the development of a new root canal sealer. Furthermore, this review shows the potential application of bioactive glass-based cement as a root canal filling material in the absence of semisolid core material.

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.

Pulpal responses after direct pulp capping with two calcium-silicate cements in a rat model

Bioactivity of Bio-MA, a calcium chloride accerelator-containing calcium-silicate cement, as a pulp capping material was evaluated on mechanically exposed rat molar pulp. Sixty maxillary first molars from Wistar rats were mechanically exposed and assigned to two capping materials: Bio-MA or white mineral trioxide aggregate (WMTA), and three periods: 1, 7, or 30 days. Nine molars were exposed and covered with polytetrafluoroethylene tape, as positive controls. From histological examination, inflammatory cell infiltration and reparative dentin formation were evaluated using grading scores. No significant difference in pulpal responses between the two materials was observed at any period (p>0.05). At 1 day, all experimental groups showed localized mild inflammation. At 7 days, dentin bridge was partially observed at exposure sites with few inflammatory cells. At 30 days, pulp appeared normal with complete tubular dentin bridges. Bio-MA with accerelator was biocompatible similar to WMTA and could be used as a pulp-capping material.

A novel, doped calcium silicate bioceramic synthesized by sol-gel method: Investigation of setting time and biological properties

The aim of the current study was to synthesize a fast-setting ion-doped calcium silicate bioceramic by the sol-gel method and to characterize its in vitro apatite-forming ability and cell viability. Calcium silicate (CS), doped calcium silicate with zinc and magnesium, with Ca/Zn molar ratios of 6.7:1 (DCS1), and 4.5:1 (DCS2), were synthesized by the sol-gel method. Matreva white MTA (WMTA, Matreva, CA, Egypt) was used as a control. The synthesized powders were characterized by x-ray diffraction. Setting time was measured using the Gilmore needle indentation technique. The in vitro apatite-forming ability of the materials was evaluated by scanning electron microscope and energy dispersive X-ray. NIH3T3-E1 cells viability was tested using MTT assay. The ion release of Ca, Si, Zn, and Mg was measured using inductive coupled plasma-optical emission spectroscopy (ICP-OES). One-way ANOVA was used to analyze setting time results. The Tukey's HSD post hoc test was used to establish significance (p < 0.001). For nonparametric data, the Kruskal-Wallis H test with Dunn's correction for post hoc comparison was used (p < 0.05). CS, DCS1, and DCS2 showed a significant decrease in setting time 33 ± 1.63 min, 28 ± 1.63 min, and 41.75 ± 2.87 min, respectively, compared to WMTA 91 ± 3.16 min (p < 0.001). DCS1 showed the highest apatite-forming ability and cell viability compared to the other groups. Ca and Si ions release decreased in both DCS1 and DCS2. The physical and biological properties of CS can be successfully improved by the sol-gel synthesis and ions doping. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:56-66, 2020.

Regenerative Endodontic Procedures Using Contemporary Endodontic Materials

Calcium hydroxide apexification and Mineral Trioxide Aggregate (MTA) apexification are classical treatments for necrotic immature permanent teeth. The first tend to fail for lack of compliance given the high number of sessions needed; the second has technical difficulties such as material manipulation and overfilling. With both techniques, the root development is interrupted leaving the tooth with a fragile root structure, a poor crown-to-root ratio, periodontal breakdown, and high risk of fracture, compromising long-term prognosis of the tooth. New scientific literature has described a procedure that allows complete root development of these specific teeth. This regenerative endodontic procedure (REP) proposes the use of a combination of antimicrobials and irrigants, no canal walls instrumentation, induced apical bleeding to form a blood clot and a tight seal into the root canal to promote healing. MTA is the most used material to perform this seal, but updated guidelines advise the use of other bioactive endodontic cements that incorporate calcium and silicate in their compositions. They share most of their characteristics with MTA but claim to have fewer drawbacks with regards to manipulation and aesthetics. The purpose of the present article is to review pertinent literature and to describe the clinical procedures protocol with its variations, and their clinical application.

Biocompatibility evaluation of Jordanian Portland cement for potential future dental application

Background

The demand for novel Portland cement (PC)-based formulations to be used in dental applications is ever increasing in viewing the foregoing knowledge on the favorable effects of these formulations on cellular proliferation and healing, leading to treatment success.

Aim

This study investigated the effect of white and gray mineral trioxide aggregate (W-MTA and G-MTA) and white and gray Jordanian PC (W-PC and G-PC) in their raw state on the viability of Balb/C 3T3 fibroblasts using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Materials and Methods

Materials were prepared in the form of disks, with a diameter of 5 mm and a thickness of 2 mm. In the first experiment, Balb/C 3T3 fibroblasts were cultured with the material disks using culture plate inserts. In the second experiment, material elutes were added to cultured cells. The elutes were prepared by adding 2 ml serum-free media to 10 disks of each material and then incubated at 37°C for different time intervals. Material elutes were analyzed using ion chromatography for traces of calcium. The data were analyzed using analysis of variance followed by Dunnett test (α = 0.05) or Tukey test (α = 0.05).

Results

In response to material disks, G-PC had a proliferative effect on cells at day 1 and day 2 with a significant difference from the control at day 1. G-MTA reduced cell viability with a significant difference from the control level at day 2. Elutes of PC showed biocompatible and even proliferative effects on Balb/C 3T3 fibroblasts. Calcium ions were found to leach continuously over the measurement period for all the materials tested in this work.

Conclusion

Jordanian PC in its raw state was found to be biocompatible, and the results of this work give promise of its wider use as a base for further development to improve the physiochemical and mechanical properties of the material.

Ytterbium Oxide as Radiopacifier of Calcium Silicate-Based Cements. Physicochemical and Biological Properties

This study evaluated physicochemical properties, cytotoxicity and bioactivity of MTA Angelus (MTA), calcium silicate-based cement (CSC) and CSC with 30% Ytterbium oxide (CSC/Yb2O3). Setting time was evaluated using Gilmore needles. Compressive strength was evaluated in a mechanical machine. Radiopacity was evaluated using radiographs of materials and an aluminum scale. Solubility was evaluated after immersion in water. Cell viability was evaluated by means of MTT assay and neutral red staining, and the mineralization activity by using alkaline phosphatase activity and Alizarin Red staining. The data were submitted to ANOVA, Tukey and Bonferroni tests (5% significance). The bioactive potential was evaluated by scanning electron microscopy. The materials presented similar setting time. MTA showed the lowest compressive strength. MTA and CSC/Yb2O3 presented similar radiopacity. CSC/Yb2O3 showed low solubility. Saos-2 cell viability tests showed no cytotoxic effect, except to 1:1 dilution in NR assay which had lower cell viability when compared to the control. ALP at 1 and 7 days was similar to the control. MTA and CSC had greater ALP activity at 3 days when compared to control. All the materials present higher mineralized nodules when compared with the control. SEM analysis showed structures suggesting the presence of calcium phosphate on the surface of materials demonstrating bioactivity. Ytterbium oxide proved to be a properly radiopacifying agent for calcium silicate-based cement since it did not affected the physicochemical and biological properties besides preserving the bioactive potential of this material.

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.

Calcium phosphate precipitation in experimental gaps between fluoride-containing fast-setting calcium silicate cement and dentin

A novel fast-setting calcium silicate cement containing fluoride (novel-CSC) has been developed for applications in tooth crowns. The aim of this study was to assess the ability of the novel-CSC to close the experimental gaps at the dentin-cement interface. The novel-CSC was tested against Vitrebond and GC Fuji II LC. Experimental gaps of 50 or 300 μm width were created between the materials and dentin. Specimens with the 300-μm-wide gap were immersed in phosphate-buffered saline and the closed gap area was measured during 96 h. All specimens with 50 or 300 μm gap width were analyzed by scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX) to assess the morphology and chemical composition of the precipitates after 96 h immersion in phosphate-buffered saline. High-resolution micro-computed tomography (μCT) was used to evaluate the integrity and continuity of the precipitiates after 96 h and 180 d. In all novel-CSC samples, precipitates closed the gap area completely after 96 h. The SEM/EDX revealed that the globular precipitates closing the gap area were mainly composed of calcium and phosphorus. After 180 d, μCT indicated thicker precipitates compared with initial precipitates only in the novel-CSC group, whereas no precipitates were observed in resin-modified glass ionomers. Novel-CSC promoted continuous precipitation of calcium phosphate, including apatite, and closed the experimental gaps.

Effect of Exposed Surface Area, Volume and Environmental pH on the Calcium Ion Release of Three Commercially Available Tricalcium Silicate Based Dental Cements

Tricalcium silicate cements (TSC) are used in dental traumatology and endodontics for their bioactivity which is mostly attributed to formation of calcium hydroxide during TSC hydration and its subsequent release of calcium and hydroxide ions. The aim of this study was to determine the effect of volume (Vol), exposed surface area (ESA) and pH of surrounding medium on calcium ion release. Three commercially available hydraulic alkaline dental cements were mixed and condensed into cylindrical tubes of varying length and diameter (n = 6/group). For the effect of ESA and Vol, tubes were immersed in 10 mL of deionized water. To analyze the effect of environmental pH, the tubes were randomly immersed in 10 mL of buffer solutions with varying pH (10.4, 7.4 or 4.4). The solutions were collected and renewed at various time intervals. pH and/or calcium ion release was measured using a pH glass electrode and atomic absorption spectrophotometer respectively. The change of pH, short-term calcium ion release and rate at which calcium ion release reaches maximum were dependent on ESA (p < 0.05) while maximum calcium ion release was dependent on Vol of TSC (p < 0.05). Maximum calcium ion release was significantly higher in acidic solution followed by neutral and alkaline solution (p < 0.05).

Diametral tensile strength of novel fast-setting calcium silicate cement

Novel fast-setting calcium silicate cement with fluoride (CSC) has been developed for potential applications in tooth crown. The aim of this study was to test the diametral tensile strength (DTS) of different CSC compositions in humid condition on day1, 28, and 180. We tested 'bond CSC' with 3.5% fluoride and no radiocontrast, 'CSC' with 3.5% fluoride and 10% radiocontrast, 'ultrafast CSC' with 3.5% fluoride and 20% radiocontrast, 'high fluoride CSC' with 15% fluoride and 25% radiocontrast, Biodentine, and MTA. We filled the cements after mixing to cylindrical molds. Specimens were stored in >95% humidity. DTS was measured at each time point. CSC compositions had statistically higher DTS compared to MTA and Biodentine on day1. Bond CSC showed higher DTS versus all cements, except CSC, at all time points. DTS of all cements, except Biodentine, significantly increased in humid condition on day28 and day180 compared to day1.

The effect of moisture conditions on the constitution of two bioceramic-based root canal sealers

Background/purpose

Intraradicular moisture is not standardized and alters the sealing properties and adhesion of root sealers. The aim of this work was to evaluate the effect of different moisture on the constitution of bioceramic sealers.

Materials and methods

The sealers were evaluated before mixing, and after setting using X-ray diffraction (XRD), Energy Dispersive Analysis (EDX) and Scanning Electron Microscope (SEM) techniques. Twenty four extracted teeth were prepared and assigned to four groups according to the moisture conditions: (1) dry: using ethanol as final irrigation, (2) normal: using paper points until the last one appeared dry, (3) moist: using a Luer adapter for 5 s followed by 1 paper point, and (4) wet: the canals remained totally flooded. The roots were filled with MTA Fillapex^® and Endosequence^® BC and kept in phosphate buffer solution at 37 °C for 10 days. Each root was sectioned transversally and longitudinally. The sealers harvested from longitudinal sections were analysed using XRD. Whilst the transverse sections were analysed using SEM/EDX.

Results

The XRD analysis showed MTA Fillapex composed of Bismuth trioxide, calcium silicate and tricalcium aluminate. The intensity of peaks in the wet condition was reduced. Endosequence BC contained mainly calcium silicate, calcium silicate hydrate, zirconia and calcium hydroxide. The wet condition showed a small increase in hydrated calcium silicate. The EDX analysis showed changes in the elemental concentrations with different moisture conditions. The surface morphology differed with different moisture conditions.

Conclusion

Tested sealers have different constitution that not affected by the degree of moisture. However, it changed their relative quantity.

Innovative root-end filling materials based on calcium-silicates and calcium-phosphates

This in vitro study evaluated the apical sealing ability, bioactivity and biocompatibility of an experimental calcium silicate-based and two light-curing calcium silicate/calcium-phosphate cements as potential root end filling materials. A calcium silicate Portland-based (Control PC), an experimental calcium silicate (Exp. PC) and two light-curing cements (LC-CaP; LC-Si/CaP) were assessed for their alkalinising activity (pH) and biocompatibility. Single-rooted human canines were endodontically treated, filled with gutta-percha and finally submitted to apicoectomy. Root end fillings were performed using all tested cements, and their apical sealing ability was evaluated up to 4 weeks of immersion in simulated body fluid (SBF). The mineral precipitation at the apical region and the cement adaptation to root dentine were also evaluated through non-destructive optical microscopy both at 24 h and after prolonged water storage (four week). LC-CaP and LC-Si/CaP had neutral pH, the greatest sealing ability (24 h) and excellent cytocompatibility. The Exp. PC cement presented sealing ability after two and four weeks, as well as biocompatibility after four and seven days, similar to LC-CaP and LC-Si/CaP. The control PC cement showed the lowest sealing ability and the greatest cytotoxicity. Mineral precipitation was observed in all groups, while some differences were seen in terms of cement adaptation along the root canal dentine walls. The experimental light-curable cements as well as the experimental PC might be suitable root end filling materials with appropriate (in vitro) sealing ability, biocompatibility and aptitude to induce mineral precipitation.

Antimicrobial activity of ProRoot MTA in contact with blood

Dental materials based on Portland cement, which is used in the construction industry have gained popularity for clinical use due to their hydraulic properties, the interaction with tooth tissue and their antimicrobial properties. The antimicrobial properties are optimal in vitro. However in clinical use contact with blood may affect the antimicrobial properties. This study aims to assess whether antimicrobial properties of the Portland cement-based dental cements such as mineral trioxide aggregate (MTA) are also affected by contact with blood present in clinical situations. ProRoot MTA, a Portland cement-based dental cement was characterized following contact with water, or heparinized blood after 1 day and 7 days aging. The antimicrobial activity under the mentioned conditions was assessed using 3 antimicrobial tests: agar diffusion test, direct contact test and intratubular infection test. MTA in contact with blood was severely discoloured, exhibited an additional phosphorus peak in elemental analysis, no calcium hydroxide peaks and no areas of bacterial inhibition growth in the agar diffusion test were demonstrated. ProRoot MTA showed limited antimicrobial activity, in both the direct contact test and intratubular infection test. When aged in water ProRoot MTA showed higher antimicrobial activity than when aged in blood. Antimicrobial activity reduced significantly after 7 days. Further assessment is required to investigate behaviour in clinical situations.

Evaluation of the Ca ion release, pH and surface apatite formation of a prototype tricalcium silicate cement

AIM

To evaluate the Ca²⁺ -releasing, alkalizing and apatite-like surface precipitate-forming abilities of a prototype tricalcium silicate cement, which was mainly composed of synthetically prepared tricalcium silicate and zirconium oxide radiopacifier.

METHODOLOGY

The prototype tricalcium silicate cement, white ProRoot MTA (WMTA) and TheraCal LC (a light-cured resin-modified calcium silicate-filled material) were examined. The chemical compositions were analysed with a wavelength-dispersive X-ray spectroscopy electron probe microanalyser with an image observation function (SEM-EPMA). The pH and Ca²⁺ concentrations of water in which the set materials had been immersed were measured, and the latter was assessed with the EDTA titration method. The surface precipitates formed on the materials immersed in phosphate-buffered saline (PBS) were analysed with SEM-EPMA and X-ray diffraction (XRD). Kruskal-Wallis tests followed by Mann-Whitney U-test with Bonferroni correction were used for statistical analysis (α = 0.05).

RESULTS

The prototype cement contained Ca, Si and Zr as major elemental constituents, whereas it did not contain some metal elements that were detected in the other materials. The Ca²⁺ concentrations and pH of the immersion water samples exhibited the following order: WMTA = prototype cement > TheraCal LC (P < 0.05). All three materials produced Ca- and P-containing surface precipitates after PBS immersion, and the precipitates produced by TheraCal LC displayed lower Ca/P ratios than those formed by the other materials. XRD peaks corresponding to hydroxyapatite were detected in the precipitates produced by the prototype cement and WMTA.

CONCLUSION

The prototype tricalcium silicate cement exhibited similar Ca²⁺ -releasing, alkalizing and apatite-like precipitate-forming abilities to WMTA. The Ca²⁺ -releasing, alkalizing and apatite-like precipitate-forming abilities of TheraCal LC were lower than those of the other materials.

Bioactive mesoporous wollastonite particles for bone tissue engineering

The current investigation was aimed at identifying the role of mesoporous wollastonite particles on the healing of rat tibial bone defect. The bone defect was created with a 3-mm-diameter dental drill, and it was filled with mesoporous wollastonite particles. After second and fourth weeks of filling treatments, it was found that mesoporous wollastonite particles promoted bone formation as evidenced by X-ray, histological, scanning electron microscope, and energy-dispersive spectra studies. X-ray study showed the closure of drill hole as seen by high-dense radio-opacity image. Histological analysis depicted the deposition of collagen in the bone defect area in response to mesoporous wollastonite particles’ treatment. Scanning electron microscope–energy-dispersive spectra analyses of the sectioned implants also identified the deposition of apatite by these particles. Thus, our results suggested that mesoporous wollastonite particles have bioactive properties, and they can be used as a suitable filling material for promotion of bone formation in vivo.

Modified tricalcium silicate cement formulations with added zirconium oxide

OBJECTIVES

This study aims to investigate the effect of modifying tricalcium silicate (TCS) cements on three key properties by adding ZrO₂.

MATERIALS AND METHODS

TCS powders were prepared by adding ZrO₂ at six different concentrations. The powders were mixed with 1 M CaCl₂ solution at a 3:1 weight ratio. Biodentine (contains 5 wt.% ZrO₂) served as control. To evaluate the potential effect on mechanical properties, the mini-fracture toughness (mini-FT) was measured. Regarding bioactivity, Ca release was assessed using ICP-AES. The component distribution within the cement matrix was evaluated by Feg-SEM/EPMA. Cytotoxicity was assessed using an XTT assay.

RESULTS

Adding ZrO₂ to TCS did not alter the mini-FT (p = 0.52), which remained in range of that of Biodentine (p = 0.31). Ca release from TSC cements was slightly lower than that from Biodentine at 1 day (p > 0.05). After 1 week, Ca release from TCS 30 and TCS 50 increased to a level that was significantly higher than that from Biodentine (p < 0.05). After 1 month, Ca release all decreased (p < 0.05), yet TCS 0 and TCS 50 released comparable amounts of Ca as at 1 day (p > 0.05). EPMA revealed a more even distribution of ZrO₂ within the TCS cements. Particles with an un-reacted core were surrounded by a hydration zone. The 24-, 48-, and 72-h extracts of TCS 50 were the least cytotoxic.

CONCLUSIONS

ZrO₂ can be added to TCS without affecting the mini-FT; Ca release was reduced initially, to reach a prolonged release thereafter; adding ZrO₂ made TCS cements more biocompatible.

CLINICAL RELEVANCE

TCS 50 is a promising cement formulation to serve as a biocompatible hydraulic calcium silicate cement.

Determination of trace elements in rat organs implanted with endodontic repair materials by ICP-MS

To investigate the levels of seven elements using an inductively coupled plasma-mass spectrometry (ICP-MS) method in rat organs after the implantation of Micro Mega Mineral Trioxide Aggregate (MM-MTA), Bioaggregate (BA) and Biodentine (BD) materials. MM-MTA, BA and BD were implanted into the subcutaneous tissue of 15 Wistar albino rats; three control animals had no operation. After 45 days, the rats were sacrificed and their brains, kidneys and livers were removed. The ICP-MS analysis was used to determine trace elements. Data were analysed using the Kruskal-Wallis and Connover post hoc tests. There was no significant difference between the control groups and the MM-MTA, BA and BD groups according to the concentration of aluminum, calcium, arsenic and lead in the rats' organs. Beryllium was not detected in all tissue samples. Chromium levels of these materials were higher than the control group in brain and kidney samples (P = 0.038 and P = 0.037); magnesium levels were higher than the control group in kidney and liver samples (P = 0.030 and P = 0.008). MM-MTA, BA and BD were nontoxic according to trace element levels in brain, kidney and liver samples of rats. Further investigation is required to understand the systemic effects of these materials.

Adhesive interface and bond strength of endodontic sealers to root canal dentine after immersion in phosphate-buffered saline

This study evaluated the bond strength (BS) and the adhesive interface of four endodontic sealers to root canal dentine, before, and after immersion in phosphate buffered saline (PBS) to simulate an in vivo environment. Eighty roots were instrumented using ProTaper rotatory files, under irrigation with 17% EDTA and 1% NaOCl. Posteriorly were divided into four groups (n = 20) according to the sealer used: Endofill, AH Plus, Sealapex, and MTA Fillapex. Each group was divided into two subgroups (n = 10) and stored at 37°C immersed in water for 7 days and in PBS for 60 days. From each subgroup, 1 mm thick sections were obtained. One section of each region (coronal, middle, and apical) was submitted to the push-out test and failures were observed. Twelve sections of each subgroup (four from each region) were evaluated under SEM. Three-way ANOVA evaluation for BS showed significant differences between groups and regions (P < 0.0001), but not between subgroups (P > 0.05). AH Plus had significantly higher BS than the others sealers, regardless of the analyzed subgroup (Tukey's test, P < 0.5). The most common failures were adhesive to dentine and cohesive of the sealer. The SEM evaluation (Kruskal-Wallis, Mann-Whitney) showed homogeneous adhesive interface formed and sealer tags in all groups with significant statistical differences with AH Plus, regardless of PBS immersion. AH Plus was superior to the other sealers for both BS and quality of interface formation. Immersion in PBS did not interfere on BS or adhesive interface of the sealers tested.

A review of the bioactivity of hydraulic calcium silicate cements

OBJECTIVES

In tissue regeneration research, the term "bioactivity" was initially used to describe the resistance to removal of a biomaterial from host tissues after intraosseous implantation. Hydraulic calcium silicate cements (HCSCs) are putatively accepted as bioactive materials, as exemplified by the increasing number of publications reporting that these cements produce an apatite-rich surface layer after they contact simulated body fluids.

METHODS

In this review, the same definitions employed for establishing in vitro and in vivo bioactivity in glass-ceramics, and the proposed mechanisms involved in these phenomena are used as blueprints for investigating whether HCSCs are bioactive.

RESULTS

The literature abounds with evidence that HCSCs exhibit in vitro bioactivity; however, there is a general lack of stringent methodologies for characterizing the calcium phosphate phases precipitated on HCSCs. Although in vivo bioactivity has been demonstrated for some HCSCs, a fibrous connective tissue layer is frequently identified along the bone-cement interface that is reminiscent of the responses observed in bioinert materials, without accompanying clarifications to account for such observations.

CONCLUSIONS

As bone-bonding is not predictably achieved, there is insufficient scientific evidence to substantiate that HCSCs are indeed bioactive. Objective appraisal criteria should be developed for more accurately defining the bioactivity profiles of HCSCs designed for clinical use.