Physical and Chemical Properties and Subcutaneous Implantation of Mineral Trioxide Aggregate Mixed with Propylene Glycol

The effect of three additives on properties of mineral trioxide aggregate cements: a systematic review and meta-analysis of in vitro studies

BACKGROUND

Several efforts have been made to improve mechanical and biological properties of calcium silicate-based cements through changes in chemical composition of the materials. This study aimed to investigate the physical (including setting time and compressive strength) and chemical (including calcium ion release, pH level) properties as well as changes in cytotoxicity of mineral trioxide aggregate (MTA) after the addition of 3 substances including CaCl2, Na2HPO4, and propylene glycol (PG).

METHODS

The systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Electronic searches were performed on PubMed, Embase, and Scopus databases, spanning from 1993 to October 2023 in addition to manual searches. Relevant laboratory studies were included. The quality of the included studies was assessed using modified ARRIVE criteria. Meta-analyses were performed by RevMan statistical software.

RESULTS

From the total of 267 studies, 24 articles were included in this review. The results of the meta-analysis indicated that addition of PG increased final setting time and Ca2+ ion release. Addition of Na2HPO4 did not change pH and cytotoxicity but reduced the final setting time. Incorporation of 5% CaCl2 reduced the setting time but did not alter the cytotoxicity of the cement. However, addition of 10% CaCl2 reduced cell viability, setting time, and compressive strength.

CONCLUSION

Inclusion of 2.5% wt. Na2HPO4 and 5% CaCl2 in MTA can be advisable for enhancing the physical, chemical, and cytotoxic characteristics of the admixture. Conversely, caution is advised against incorporating elevated concentrations of PG due to its retarding effect.

TRIAL REGISTRATION

PROSPERO registration number: CRD42021253707.

Synthesis and characterization of calcium-releasing elastomeric resin-based endodontic sealers

OBJECTIVES

To evaluate the incorporation of halloysite nanotubes (HNTs) loaded with one of two calcium sources (i.e., calcium hydroxide/CaOH2 or beta-tricalcium phosphate/β-TCP) on the physicochemical and biological properties of an experimental resin-based dual-cured endodontic sealer.

MATERIALS AND METHODS

HNTs were encapsulated with CaOH2 or β-TCP at 10 wt.%. HNTs containing CaOH2 or β-TCP were added into the experimental sealers at 50 wt.%. The control sealers were the calcium-free HNT-modified resin-based experimental sealer and AH Plus™, a commercially available endodontic sealer. Degree of conversion, setting time, flow, film thickness, radiopacity, dimensional stability, and calcium ions release were determined. Antibiofilm properties and cytocompatibility of the formulated sealers and commercial control were also evaluated. One and two-way ANOVA analysis followed by Tukey's post hoc test was conducted to evaluate the effect of the independent variable on the evaluated properties.

RESULTS

FTIR confirmed the encapsulation of calcium sources into HNTs. Regarding flow and film thickness, the values obtained from these sealers were in accordance with the specifications provided by ISO 6876. For radiopacity, AH Plus™ achieved the highest radiopacity (p<0.05). Among the experimental formulations, all experimental HNT-containing compositions exhibited values below 3 mm Al. The experimental sealers showed greater dimensional changes when compared to the commercial (AH Plus™) control. The release of calcium ions was observed for the HNT_CaOH2 and HNT_β-TCP sealers without statistical differences. Experimental sealers containing HNT_CaOH2 and HNT_β-TCP significantly reduced the CFU/mL count and showed cell compatibility.

CONCLUSIONS

The findings of this study demonstrate that the incorporation of HNT_CaOH2 or HNT_β-TCP into resin-based experimental sealers promoted antimicrobial effects and gradual calcium release without impairing cytocompatibility or physicochemical properties of the sealers. Still, an adjustment to reach the minimal radiopacity established by ISO 6876 is needed.

CLINICAL RELEVANCE

The experimental resin-based sealers seemed to be an alternative for endodontics. The incorporation of calcium sources exerts promising antimicrobial effects while displaying low cell toxicity.

High-plasticity mineral trioxide aggregate and its effects on M1 and M2 macrophage viability and adherence, phagocyte activity, production of reactive oxygen species, and cytokines

Objectives

This study evaluated the effects of high-plasticity mineral trioxide aggregate (MTA-HP) on the activity of M1 and M2 macrophages, compared to white MTA (Angelus).

Materials and Methods

Peritoneal inflammatory M1 (from C57BL/6 mice) and M2 (from BALB/c mice) macrophages were cultured in the presence of the tested materials. Cell viability (MTT and trypan blue assays), adhesion, phagocytosis, reactive oxygen species (ROS) production, and tumor necrosis factor (TNF)-α and transforming growth factor (TGF)-β production were evaluated. Parametric analysis of variance and the non-parametric Kruskal-Wallis test were used. Results were considered significant when p < 0.05.

Results

The MTT assay revealed a significant decrease in M1 metabolism with MTA-HP at 24 hours, and with MTA and MTA-HP later. The trypan blue assay showed significantly fewer live M1 at 48 hours and live M2 at 48 and 72 hours with MTA-HP, compared to MTA. M1 and M2 adherence and phagocytosis showed no significant differences compared to control for both materials. Zymosan A stimulated ROS production by macrophages. In the absence of interferon-γ, TNF-α production by M1 did not significantly differ between groups. For M2, both materials showed higher TNF-α production in the presence of the stimulus, but without significant between-group differences. Likewise, TGF-β production by M1 and M2 macrophages was not significantly different between the groups.

Conclusions

M1 and M2 macrophages presented different viability in response to MTA and MTA-HP at different time points. Introducing a plasticizer into the MTA vehicle did not interfere with the activity of M1 and M2 macrophages.

Efficacy of Mineral Trioxide Aggregate Repair High Plasticity, Biodentine, and EndoSequence Root Repair Material Putty as Apical Barriers in Immature Permanent Teeth: An In Vitro Bacterial Leakage Study

AIM

To assess the microleakage of mineral trioxide aggregate (MTA) repair high plasticity (HP), EndoSequence root repair material (ESRRM) putty, and Biodentine, when used as an apical plug in immature permanent teeth.

MATERIALS AND METHODS

In an in vitro model, 55 extracted maxillary incisors were decoronated and resected 3 mm apically to obtain standardized 15-mm root blocks, which were then cleaned and shaped. All samples had a 1.1-mm standardized, prepared artificial open apex. The teeth were arbitrarily designated into three experimental groups (n = 15) and two control (positive/negative) groups (n = 5). In the experimental groups, orthograde 4-mm thick apical plugs of Biodentine (group I), ESRRM putty (group II), and MTA repair HP (group III) were placed. Positive control samples were left vacant while negative control samples were filled with Biodentine. The bacterial leakage method was used to appraise the sealing efficiency of the cements.

RESULTS

Statistical package for the social sciences (SPSS) software, version 21.0, was used for data analysis. Post hoc Tukey's test, one-way analysis of variance (ANOVA), and repeated measures of ANOVA were used for intergroup and intragroup comparisons. On day 1, there was a significant difference between the groups, with group II showing the least and group 1 showing the maximum microleakage. No significant difference among the groups was seen at other observational periods. There was a tendency for leakage to increase significantly from day 1 to 7, then decrease till the end of the experimental period.

CONCLUSION

It was concluded that the three materials evaluated, with time, exhibited comparable apical microleakage when treating teeth with open apices.

CLINICAL SIGNIFICANCE

MTA repair HP can be used as an apical plug material in open apices with similar success as ESRRM putty and marginally better outcome than Biodentine.

Effect of nonsteroidal anti-inflammatory drugs (NSAIDs) association on physicochemical and biological properties of tricalcium silicate-based cement

The aim of this study was to investigate the physicochemical and biological properties of an experimental tricalcium silicate-based repair cement containing diclofenac sodium (CERD). For the physicochemical test, MTA, Biodentine and CERD were mixed and cement disc were prepared to evaluate the setting time and radiopacity. Root-end cavity were performed in acrylic teeth and filled with cements to analyze the solubility up to 7 days. Polyethylene tubes containing cements were prepared and calcium ions and pH were measured at 3h, 24h, 72h and 15 days. For the biological test, SAOS-2 were cultivated, exposed to cements extracts and cell proliferation were investigated by MTT assay at 6h, 24h and 48h. Polyethylene tubes containing cements were implanted into Wistar rats. After 7 and 30 days, the tubes were removed and processed for histological analyses. Parametric and nonparametric data were performed. No difference was identified in relation to setting time, radiopacity and solubility. Biodentine released more calcium ion than MTA and CERD; however, no difference between MTA and CERD were detected. Alkaline pH was observed for all cements and Biodentine exhibited highest pH. All cements promoted a raise on cell proliferation at 24h and 48h, except CERD at 48h. Biodentine stimulated cell metabolism in relation to MTA and CERD while CERD was more cytotoxic than MTA at 48h. Besides, no difference on both inflammatory response and mineralization ability for all cement were found. CERD demonstrated similar proprieties to others endodontic cements available.

Biological and antimicrobial properties of the association Ambroxol and a water-soluble viscous liquid as a vehicle for a tricalcium silicate-based sealer

This study aimed to investigate the antimicrobial and biological properties of Ambroxol associated with glycerin (GLI), propylene glycol (PG), and polyethylene glycol (PEG) as a possible vehicle for an experimental tricalcium silicate sealer, with the intention of developing a new biomaterial. Mouse undifferentiated dental pulp cells (OD-21) were cultured, and the effects of different association on cell proliferation and inflammatory cytokine production were investigated. Antimicrobial adhesion of Enterococcus faecalis to setting sealers at 2 h was evaluated. Polyethylene tubes containing experimental sealers and empty tubes were implanted into dorsal connective tissues of 12 male 3- to 4-months-old Wistar rats (250-280 g). After 7 and 30 days, the tubes were removed and processed for histological and immunohistochemical analyses. ANOVA followed by Bonferroni correction and ANOVA followed by Tukey test was used for parametric data and Kruskal-Wallis followed by Dunn for nonparametric (p < 0.05). Cell proliferation was dose-dependent, since all association were cytotoxic at higher concentrations; however, Ambroxol-PEG showed significantly higher cytotoxicity than other association (p < 0.05). In addition, irrespective of the association, no cytokine production was observed in vitro. Ambroxol-GLI reduced bacterial viability, whereas Ambroxol-PEG increased (p < 0.05). Histological examination showed no significant difference in the inflammatory response (p > 0.05) and mineralization ability in all association. Additionally, IL-1β and TNF-α were upregulated on Ambroxol-PEG in relation to Control at 07 days (p < 0.05). Ambroxol-GLI was the best vehicle for experimental tricalcium silicate sealer, as it promoted an increase in antimicrobial activity without altering the inflammatory response or mineralization ability.

Effect of Irrigating Agitation after Root End Preparation on the Wall Cleaning and Bond Strength of Calcium Silicate Material in Retrograde Obturation

Objective This study aimed to evaluate the cleaning efficacy of irrigant activation with a new ultrasonic tip in root-end preparations and to determine its influence on the bond strength of calcium silicate-based material.

Materials and Methods Maxillary canines were prepared and filled, and their root ends resected. Root-end cavities were ultrasonically prepared and randomly distributed into four groups according to the final irrigation protocols: G1 (ultrasonic irrigation [UI] + saline solution [SS]), G2 (syringe irrigation [SI] + SS), G3 (UI + ethylenediaminetetraacetic acid [EDTA]), and G4 (SI + EDTA). Cleaning efficacy analysis employed 72 specimens ( n = 18) split longitudinally for imaging of the same areas by scanning electron microscopy (SEM). The percentage of dentinal tubules opened before and after irrigation was used as evaluation parameter. Push-out testing employed 40 specimens ( n = 10) sectioned apical region perpendicularly, which slice was placed on a testing machine for the bond strength measurement and failure mode was assessed by SEM. The data were statistically analyzed (α ≤ 0.05).

Results G3 (UI + EDTA) removed the smear layer more effectively, showed the best tubule opening ( p < 0.05), and presented the highest mean bond strength values ( p < 0.05). Failure modes were predominantly adhesive, except for the G3 (UI + EDTA) group, in which they were mainly mixed (80%).

Conclusion The results of this study suggest that EDTA 17% agitation promoted better cleaning and smear layer removal, improving the push-out bond strength of calcium silicate material in retrograde obturation.

The in vitro evaluation of antibacterial efficacy optimized with cellular apoptosis on multi-functional polyurethane sealers for the root canal treatment

To solve the high instances of failure caused by endodontic reinfection, herein, an improved root filling material was produced to meet the multi-functional demand of sealers for root canal therapy. In this study, polyurethane (PU)-based nanocomposites were prepared by loading bismuth oxide, hydroxyapatite and antibacterial agents, namely Ag₃PO₄ and ZnO nanoparticles, which were named CP-Ag and CP-Zn sealers, respectively. A parallel biological evaluation at bacterial and cellular levels was performed to determine the fate of the different components of the PU-based sealers. Furthermore, the composition of sealers was quantified by screening their antibacterial activity and apoptotic factors, considering the potential toxicity of the nanoparticles and high dosage of metals. The in vitro optimization investigation was conducted systematically against Streptococcus mutans and Staphylococcus aureus, including bacteriostatic and dynamic tests, and the expression of the B-cell lymphoma-2 gene family and caspase proteases in the mitochondria-mediated apoptotic pathway was evaluated using the commercial AH Plus® and Apexit® Plus sealers for comparison. Additionally, the physical properties and sealing ability of sealers were assessed. The results showed that all PU-based sealers could meet the requirements of ISO 6876:2012 for root canal sealing materials. Based on the evaluation system, CP-Zn sealers expressed longer lasting antibacterial activity and lower toxic effect on cells compared to CP-Ag sealers. Especially, the CP-Zn5 sealer exhibited selective antimicrobial efficacy and hypo-toxicity, which were better than that of the two commercial sealers. According to the two-dimensional and three-dimensional methods, the good sealing ability of the CP-Zn5 sealer is the same as the excellent filling characters of AH Plus, which adapts to irregular root canals.

Tannic acid speeds up the setting of mineral trioxide aggregate cements and improves its surface and bulk properties

HYPOTHESIS

The setting time and mechanical properties of cements are a major technical concern for a long time in civil engineering. More recently those practical problems became a major concern for biomedical applications -in bone surgery and in dentistry- in particular concerning the setting time which should be minimized. The possibility to add organic additives to interact with the different constituting ions in cements constitutes a way to modify the setting kinetics. We made the assumption that a hydrolysable polyphenol like tannic acid could modify the setting time and the physical properties of Mineral Trioxide Aggregate (MTA).

EXPERIMENTS

Tannic acid is added in variable proportions to the water used to set MTA. The formation of the hybrid organic-mineral cements is investigated using a combination of structural, chemical and mechanical methods. X-ray tomography was also used to investigate the changes in porosity and pore size distribution upon incorporation of tannic acid in MTA based cements. The hydrophilicity of the cements was evaluated by measuring the permeation kinetics of small water droplets.

FINDINGS

We found that tannic acid allowed to reduce markedly the setting time of MTA based cements. The obtained cements have an increased hydrophilicity and display excellent resistance to compression. The number of pores but not the average pore size is also affected. The possible roles of tannic acid in modifying the cement properties are discussed.

The Effectiveness of Laser-Activated Irrigation on the Apical Microleakage Qualities of MTA Repair HP and NeoMTA Plus in Simulated Immature Teeth: A Comparative Study

There are limited data regarding the potential effect of erbium, chromium: yttrium–scandium–gallium–garnet (Er,Cr:YSGG) laser-activated irrigation (LAI) on the microleakage qualities of calcium silicate-based cements. The objective of the present study was to assess the effect of LAI on the microleakage qualities of MTA Repair HP (MTA-HP) and NeoMTA Plus (Neo) used in root-end filling and to compare the antimicrobial effectiveness of MTA- HP. Two experimental sets were conducted: antimicrobial activity (agar diffusion test/at 24, 48 h) and microleakage (glucose leakage model/at 1st, 10th, 20th days). Antimicrobial activities of MTA-HP, Neo, Biodentine, ProRoot and MTA Angelus were evaluated, and inhibition zones were observed not only against a range of Gram-positive and Gram-negative bacteria but also against yeast at 48h. For microleakage evaluation, fifty teeth were prepared to simulate the clinical situation where the root-tips (apex) are open, and randomly divided into two experimental groups (n = 20/group) according to the cement type (MTA-HP and Neo), and two control (n = 5/group) groups. Each experimental group was further divided into two subgroups (n = 10/group) with respect to LAI: MTA-HP, L-HP, Neo, L-Neo. A statistical difference was only detected between Neo and L-HP groups on day 1. Subsequently, MTA-HP exhibited superior microleakage quality compared to Neo in the short-term. Er,Cr:YSGG laser-activated irrigation could be used as a reliable technique without creating adverse effects on the sealing abilities of MTA Repair HP and NeoMTA Plus.

Physicochemical, cytotoxicity and in vivo biocompatibility of a high-plasticity calcium-silicate based material

The purpose of this work was to evaluate the physicochemical properties, the cytotoxicity and in vivo biocompatibility of MTA Repair HP (MTA HP) and White MTA (WMTA). The setting time, flow, radiopacity and water solubility were assessed. To the cytotoxicity assay, primary human osteoblast cells were exposed to several dilutions of both materials eluates. MTT assay, apoptosis assay and cell adhesion assay were performed. The in vivo biocompatibility was evaluated through histological analysis using different staining techniques. No differences were observed between MTA HP and WMTA for setting time, radiopacity, solubility and water absorption (P > 0.05). However, MTA HP showed a significantly higher flow when compared to WMTA (P < 0.05). Cell viability results revealed that the extracts of WMTA and MTA HP promoted the viability of osteoblasts. After incubation of cells with the endodontic cement extracts, the percentage of apoptotic or necrotic cells was very low (<3%). Furthermore, SEM results showed a high degree of cell proliferation and adhesion on both groups. MTA HP showed similar in vivo biocompatibility to the WMTA and the control group in all time-points. The MTA HP presented adequate physicochemical and biological properties with improved flow ability when compared to WMTA. Such improved flow ability may be a result of the addition of a plasticizing agent and should be related to an improvement in the handling of MTA HP.

Higher hydration performance and bioactive response of the new endodontic bioactive cement MTA HP repair compared with ProRoot MTA white and NeoMTA plus

The aim of this study was to characterize the hydration performance and the bioactive response of the new bioactive endodontic cement MTA HP repair (HP), comparing its physicochemical parameters with those of ProRoot MTA White (Pro) and NeoMTA Plus (Neo). Un-hydrated precursor materials were characterized by X-ray fluorescence, laser diffraction, N₂ physisorption and field emission gun scanning electron microscopy (FEG-SEM). Setting time was assessed according to ASTM specification C 266. Hydrated materials were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR) and (FEG-SEM). Bioactivity evaluation in vitro was carried out, by soaking processed cement disk in simulated body fluid (SBF) during 168 h. The cements surface was studied by FT-IR, FEG-SEM, and energy dispersive X-ray. Release to the SBF media of ionic degradation products was monitored using inductively coupled plasma atomic emission spectroscopy. HP showed shorter initial setting time compared to Pro and Neo and produce a quick and effective bioactive response in vitro in terms of phosphate phase surface coating formation. This higher bioactive response for HP is correlated with increasing calcium aluminate content, increasing surface area of un-hydrated powder precursor and the increasing release capacity of Si ionic products of the final hydrated product. The higher bioactive response of MTA HP repair highlights this material, as very interesting to further investigate its performance to improve the outcome of vital pulp therapy procedures. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2109-2120, 2019.

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.

Interaction of backfilling techniques and MTA plugs with additives: Fracture strength and adaptation analyses

The aims were to evaluate the effects of different additives on the adaptation of mineral trioxide aggregate (MTA) plugs before and after different backfilling techniques and analyze the interference of filling procedures on the fracture resistance of simulated immature teeth. The apical parts of 60 teeth were filled with MTA mixed with distilled water (DW), propylene glycol (PG) or calcium chloride (CaCl₂) and backfilled with cold lateral condensation (CLC) or warm vertical compaction (WVC). The specimens were subjected to adaptation analysis and fracture testing. CaCl₂ addition resulted in poor marginal adaptation, while PG addition significantly decreased the fracture values (p<0.05). WVC technique negatively affected the marginal adaptation of MTA-CaCl₂ plugs and decreased the fracture values of teeth with MTA-PG plugs (p<0.05). Mixing MTA with DW can be recommended as apical plug when the remaining root canal space is going to be filled with either CLC or WVC techniques.

Mineral Trioxide Aggregate-A Review of Properties and Testing Methodologies

Mineral trioxide aggregate (MTA) restoratives and MTA sealers are commonly used in endodontics. Commonly referenced standards for testing of MTA are ISO 6876, 9917-1 and 10993. A PubMed search was performed relating to the relevant tests within each ISO and "mineral trioxide aggregate". MTA restoratives are typically tested with a mixture of tests from multiple standards. As the setting of MTA is dependent upon hydration, the results of various MTA restoratives and sealers are dependent upon the curing methodology. This includes physical properties after mixing, physical properties after setting and biocompatibility. The tests of flow, film thickness, working time and setting time can be superseded by rheology as it details how MTA hydrates. Physical property tests should replicate physiological conditions, i.e. 37 °C and submerged in physiological solution. Biocompatibility tests should involve immediate placement of samples immediately after mixing rather than being cured prior to placement as this does not replicate clinical usage. Biocompatibility tests should seek to replicate physiological conditions with MTA tested immediately after mixing.

Classification and Nomenclature of Commercial Hygroscopic Dental Cements

Objective

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

Methods

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

Results

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

Conclusion

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

Chemical-physical Properties and Apatite-forming Ability of Mineral Trioxide Aggregate Flow

INTRODUCTION

This study aimed to analyze the chemical-physical properties, including pH, volumetric change, radiopacity, and apatite-forming ability in simulated body fluid, of a new tricalcium silicate material (MTA Flow; Ultradent Products Inc, South Jordan, UT).

METHODS

MTA Flow was tested in comparison with MTA Angelus (Angelus, Londrina, PR, Brazil). The pH of soaking water was tested up to 168 hours in deionized water. In the solubility test, the root-end fillings of 20 acrylic teeth were scanned twice by micro-computed tomographic imaging before and after immersion in ultrapure water for 168 hours. In addition, using an aluminum step wedge, the radiopacity of each material was evaluated as recommended by international standards. The mean gray values of the test materials were measured using ImageJ software (National Institutes of Health, Bethesda, MD). The morphologic and chemical analyses of the material surface were performed using scanning electron microscopic energy-dispersive X-ray spectroscopic analysis after 28 days in Hank's balanced salt solution (HBSS). The data were analyzed using 2-way analysis of variance with the Student-Newman-Keuls test (P < .05).

RESULTS

MTA Flow showed similar alkalizing activity to that of MTA Angelus. In the solubility test, both materials presented lower values without statistical differences. Both materials showed a marked alkalinizing activity within 3 hours, which continued for 168 hours. MTA Angelus showed statistically higher radiopacity values (P < .05). All materials showed the ability to nucleate calcium phosphate on their surface after 28 days in HBSS.

CONCLUSIONS

MTA Flow showed remarkable alkalinizing capability, low solubility, good radiopacity, and the ability to form calcium phosphate deposits after being soaked in simulated body fluid, showing values similar to those of MTA Angelus.

Vertical root fracture resistance of simulated immature permanent teeth filled with MTA using different vehicles

Background

The aim of the study is to evaluate the resistance vertical root fracture (VRF) of mineral trioxide aggregate (MTA) filled-immature permanent roots by using three different vehicles.

Material and Methods

Forty-extracted human single-rooted mandibular premolars were selected and the root length was standardized to the length of 9 mm. For simulation of immature tooth apices, peeso reamers were introduced into the root canals and the prepared roots were assigned into three experimental groups according the used vehicle (distilled water-DW, prophylene glycol-PG, chlorhexidine-CHX) and control group (n=10). To simulate a periodontal membrane, the apical 7 mm of all roots was covered with wax to obtain a 0.2- to 0.3-mm-thick layer before embedding the roots into acrylic cylinders. A vertical force was applied (1mm/min) using a universal testing machine and the maximum load (F-max) that fracture occurred and the fracture mode (splint or comminuted) was recorded. Data were presented as mean and standard deviations. Statistical analysis was performed using Kruskal-Wallis, Mann-Whitney U Test was used for multiple comparisons.

Results

There were significant differences between fracture strength of experimental groups with that of control group (p<0.05). However, no statistically significant differences were found amongst the fracture strength values of the experimental groups (p>0.05). In all groups, split fracture was the most common fracture mode.

Conclusions

MTA increases resistance of immature permanent teeth to VRF. Based on the results of this study, it can be concluded that mixing MTA with CHX or PG as the vehicle do not alter VRF resistance of simulated immature permanent roots.

Key words:Immature teeth, MTA, vehicle, vertical root fracture.