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Aim: The present study was conducted with the objective of evaluating the effect of different liquid-to-powder ratios on setting time of white mineral trioxide aggregate (WMTA) and the effect of adding disodium hydrogen phosphate (Na 2 HPO 4 ) to white MTA (NAMTA)., Materials and Methods: Sixty samples were prepared in plastic annular molds with a diameter of 10 mm and a height of 2 mm in order to record setting time where white MTA was placed in 30 samples and 2.5 wt% mixture of Na 2 HPO 4 with white MTA was placed in other 30 samples. Setting times in different ratios of liquid to powder (50, 60, and 70%) and at different times including 5, 10, 15, 20, 25, 30, 40, and 50 minutes as well as 1, 1.5, 2.5, 3, 3.5, and 4 hours were measured with Vicat. Statistical Package for the Social Sciences version 16 software was used to examine the differences between groups. The values of p < 0.05 were considered to be statistically significant in this study., Results: The average setting time of samples in two WMTA and NAMTA was 182.17 ± 57.86 and 67.00 ± 14.42 respectively, and this difference was statistically significant (p < 0.001). Also, the average setting time of samples in ratio groups of 50, 60, and 70% were 146.00 ± 75.90, 85.00 ± 31.71, and 142.5 ± 64.47 respectively, and results showed that there was no significant difference between groups., Conclusion: Adding 2.5 wt% of Na 2 HPO 4 mixture to white MTA reduces the setting time, which is lower than the WMTA in 50, 60, and 70% liquid-to-powder ratios., Clinical Significance: According to the findings of this study, it can be seen that adding Na 2 HPO 4 to white MTA is a good way to reduce setting timing in clinical dentistry, especially in one-visit treatments.

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

Background/aim: Elevation of pH and calcium ion release are of great importance in antibacterial activity and the promotion of dental soft and hard tissue healing process. In this study, we evaluated the effect of particle size on the elevation of pH and the calcium ion release from calcium silicate-based dental cements., Material and Methods: Twelve plastic tubes were divided into three groups, filled with white mineral trioxide aggregate (WMTA), WMTA plus 1% methylcellulose, and nano-modified WMTA (nano-WMTA), and placed inside flasks containing 10 ml of distilled water. The pH values were measured using a pH sensor 3, 24, 72, and 168 h after setting of the cements. The calcium ion release was measured using an atomic absorption spectrophotometer with same sample preparation method. Data were subjected to two-way analysis of variance (anova) followed by post hoc Tukey tests with significance level of P < 0.05., Results: Nano-WMTA showed significant pH elevation only after 24 h (P < 0.05) compared with WMTA, and after 3, 24, and 72 h compared with WMTA plus 1% methylcellulose (P < 0.05). Nano-WMTA showed significantly higher calcium ion release values compared to the other two groups (P < 0.05)., Conclusions: Nano-modification of WMTA remarkably increased the calcium ion release at all time intervals postsetting, which can significantly influence the osteogenic properties of human dental pulp cells and as a consequence enhance mineralized matrix nodule formation to achieve desirable clinical outcomes. However, the increase in pH values mainly occurred during the short time postsetting. Addition of 1% methylcellulose imposed a delay in elevation of pH and calcium ion release by WMTA., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Introduction: The aim of this study was to evaluate the effects of three different mixing techniques on surface microhardness, initial setting time, and phase formation of white mineral trioxide aggregate., Methods: Twenty-one cylindrical glass tubes were selected and divided into three groups of seven in each (n = 7). White mineral trioxide aggregate (WMTA) in groups A, B, and C were mixed by conventional, trituration, and ultrasonic techniques, respectively. Cements were mixed and packed into the glass tubes and incubated at 37°C for 3 days. After incubation, samples were subjected to microhardness evaluation, and four specimens from each group were prepared and observed under a scanning electron microscopy and X-ray diffraction. For setting time assessment, WMTA was mixed in three parts again, and Gilmore needle test was performed until the initial setting time of cement. Data were analyzed by one-way anova and post hoc Tukey's test., Results: Samples mixed by trituration technique significantly showed the highest microhardness (P < 0.001) and the lowest setting time, while the ultrasonically mixed specimens significantly revealed the highest setting time in comparison with other groups (P < 0.001). Samples mixed by trituration technique showed the highest uniformity in the bulk and highest amount of hydrated calcium silicate (CS) phases, while the lowest value was observed in ultrasonically mixed cements, which also showed the highest amount of anhydrated CS phases., Conclusion: Trituration and conventional techniques were more suitable mixing methods for mineral trioxide aggregate in comparison with ultrasonic technique. Trituration resulted in better hydration and crystallization, which prevents clustering of powder and reduces voids and setting time of mixed cement., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Introduction: To analyze the push-out bond strength of Angelus WMTA (Angelus Dental Products), a nano-modification of WMTA (Kamal Asgar Research Center) and Bioaggregate (Innovative Bioceramix)., Methods: Sixty 2-mm-thick root sections were prepared from 60 single-rooted human teeth. The dentin disks were randomly divided into three groups (n = 20) and filled with Angelus WMTA, Nano-WMTA, or Bioaggregate, respectively. Push-out bond strength values of the specimens were measured by a universal testing machine and examined under scanning electron microscope at × 40 magnification to determine the nature of the bond failure. The data were analyzed with a Kruskal-Wallis test., Results: The greatest mean for push-out bond strength (138.48 ± 11.43 MPa) was observed for the nano-modification of WMTA. The values decreased to 110.73 ± 11.19 and 25.64 ± 5.27 MPa for Angelus WMTA and Bioaggregate, respectively. There were significant differences between the groups (P < 0.001). Inspection of the samples revealed the bond failure to be predominantly adhesive type except for the nano-modification group, as some samples also exhibited cohesive failures., Conclusions: It is concluded that the force needed for the displacement of the nano-modification of WMTA (NWMTA) was significantly higher than for Angelus WMTA and Bioaggregate., (© 2012 John Wiley & Sons A/S.)

Objectives: Recently, it was shown that NanoMTA improved the setting time and promoted a better hydration process which prevents washout and the dislodgment of this novel biomaterial in comparison with WTMA. This study analyzed the compressive strength of ProRoot WMTA (Dentsply), a NanoWMTA (Kamal Asgar Research Center), and Bioaggregate (Innovative Bioceramix) after its exposure to a range of environmental pH conditions during hydration., Study Design: After mixing the cements under aseptic condition and based on the manufacturers` recommendations, the cements were condensed with moderate force using plugger into 9 × 6 mm split molds. Each type of cement was then randomly divided into three groups (n=10). Specimens were exposed to environments with pH values of 4.4, 7.4, or 10.4 for 3 days. Cement pellets were compressed by using an Instron testing machine. Values were recorded and compared. Data were analyzed by using one-way analysis of variance and a post hoc Tukey's test., Results: After 3 days, the samples were solid when probed with an explorer before removing them from the molds. The greatest mean compressive strength 133.19 ± 11.14 MPa was observed after exposure to a pH value of 10.4 for NanoWMTA. The values decreased to 111.41 ± 8.26 MPa after exposure to a pH value of 4.4. Increasing of pH had a significant effect on the compressive strength of the groups (p<0.001). The mean compressive strength for the NanoWMTA was statistically higher than for ProRoot WMTA and Bioaggregate (p<0.001). Moreover, increasing of pH values had a significant effect on compressive strength of the experimental groups (p<0.001)., Conclusion: The compressive strength of NanoWMTA was significantly higher than WMTA and Bioaggregate; the more acidic the environmental pH, the lower was the compressive strength.

Removal of MTA from dentin by applying 37% hydrochloric acid (HCl) to reduce microhardness and push-out bond strength. Forty dentin slices were filled with WMTA and divided into two groups (n = 20). Ten slices remained untreated while others were exposed to either HCl or phosphate buffer saline (PBS) and all samples were subjected to pushout test. The mode of bond failures was determined by SEM analysis. Later, twenty glass tubes were filled with WMTA and divided into two groups (n = 10). One side of tube was exposed to HCl or PBS while the other side remained untreated and the microhardness was analyzed by testing machine. HCl showed significantly lower pushout strength and microhardness values (P = 0.0001), (P = 0.0001). HCl treated samples showed mixed bond failures dominantly, while PBS samples mostly showed adhesive failures. The results of this study can suggest the 37% HCl as an effective solution to aid the removal of MTA from the dentin surfaces.

Objective: Knowledge about the effect of storage conditions on the clinical performance of Mineral Trioxide Aggregate (MTA) is of great importance for clinicians. The aim of this study was to evaluate the effect of storage temperature on sealing ability and solubility of white MTA., Materials and Methods: This study was divided into two parts: sealing ability and solubility tests. Forty single-rooted human pre-molars were divided into three experimental (n = 10) and two control groups (n = 5). The root canals were instrumented and root apices were resected. Root-end cavities were prepared and filled with white MTA stored at 4°C, 25°C or 40°C. Microleakage was evaluated using a protein leakage test with bovine serum albumin at 24-h intervals for 120 days. The solubility test was also performed based on ISO specifications (ISO 2001-6876). Data were analyzed by one-way analysis of variance and post-hoc Tukey test, with a significance level set at p = 0.05., Results: The highest bovine serum albumin microleakage and the highest solubility rates were observed in 4°C followed by 25°C and 40°C groups. At higher temperatures, leakage needed significantly longer times to occur (p < 0.05)., Conclusions: Based on these findings, storage temperature appears to play an important role in the properties and hence clinical outcomes of MTA.

Aim: To analyse the physicochemical properties of a Nano white mineral trioxide aggregate (NWMTA) and compare it with white mineral trioxide aggregate (WMTA)., Methodology: White mineral trioxide aggregate and NWMTA were prepared and mixed according to the manufacturer's instructions. Surface area of powder before hydration, setting time, X-ray diffraction and microhardness at pH values of 4.4 and 7.4 were evaluated by Brunauer-Emmett-Teller, ISO Specification no.6876, Vickers microhardness, and energy-dispersive X-ray spectroscopy equipped with X-ray colour (dot) map for both cements. anova and Mann-Whitney were used for statistical analysis at a significance level of 0.5., Results: The mean ± SD of surface area and setting time were 1.8 ± 0.2 m(2) g(-1) and 43 ± 2 min for WMTA and 7.8 ± 1.2 m(2) g(-1) and 6 ± 1 min for NWMTA, respectively. Mean ± SD of Microhardness were 16 ± 2, 51 ± 1, 69 ± 1 and 81 ± 2 for WMTA at pH values of 4.4 and 7.4 and for NWMTA correspondingly. Numbers of open porosity over the surface were 88 ± 24 and 44 ± 13 for WMTA and NWMTA, respectively. Statistical tests revealed significant differences between the groups (P < 0.001) in surface area, setting time and surface hardness for both cements. Uniform distribution of strontium was only observed in NWMTA. However, other compounds were not significantly different., Conclusion: Increasing surface area of powder can reduce setting time and increase microhardness even at lower pH values after hydration., (© 2012 International Endodontic Journal.)

Objective: The aim of this in vitro study was to evaluate the effects of diode laser, MTAD(™) and laser plus MTAD on the push-out bond strength of mineral trioxide aggregate (MTA)-dentin., Background Data: MTA has been used widely, especially in root canal therapies (RCT); however, the effect of different final treatments during RCT has been questioned regarding the retention characteristic of this cement-based material., Materials and Methods: Forty single-rooted human teeth were prepared into dentin slices and drilled to form canal spaces. Samples were divided into four groups of 10 in each (n=10). In groups A and B, diode laser irradiations were performed, and then MTA was placed inside the canal spaces and incubated at 37 °C for 7 days. After incubation, dentin slices in groups B and C were immersed in Biopure MTAD, and the last group served as control without any treatment. The push-out bond strengths were then measured by using a universal testing machine., Results: The means±standard deviations of push-out bond strength were 6.74±0.48, 5.95±0.40, 6.86±0.66, and 7.88±0.37 for groups A (laser), B (laser plus MTAD), C (MTAD) and D (control), respectively. One-way analysis of variance (ANOVA) test revealed significant differences among the groups (p<0.0001). Tukey's test did not show any significant difference between groups A and C (p=0.93). However, these differences were significant between groups A and B (p=0.006) and between groups B and C (p=0.001)., Conclusions: The results of this study indicated that either diode laser or MTAD can lower the bond strength of MTA-dentin, and that diode laser irradiations plus MTAD might affect MTA bond to dentin negatively.

Introduction: The aim of this study was to compare the effect of subcutaneously implanted white mineral trioxide aggregate (WMTA) on inflammatory reactions before and after expiry date., Methods: Fifty Wistar rats were used in this study. Polyethylene tubes were filled with WMTA with expiry dates of 2008, 2009, and 2011, and empty ones serving as the controls were implanted into the subcutaneous tissue. The rats were sacrificed at 7-, 14-, 28-, and 60-day intervals. 5-μm sections were stained with hematoxylin and eosin and observed under a light microscope. Inflammatory reactions were categorized as 0, none (without inflammatory cells); 1, mild (inflammatory cells < 25); 2, moderate (25-125 inflammatory cells); and 3, severe (more than 125 inflammatory cells). Statistical analysis was performed with Kruskal-Wallis test., Results: All the experimental materials provoked moderate to severe inflammatory reactions after 7 days, which significantly differed from the control group (P < 0.05). At 14-day interval, WMTA with expiry date of 2008 and the control group elicited mild to moderate infiltration of inflammatory cells. However, WMTA with expiry dates of 2009 and 2011 provoked moderate to severe inflammatory reactions, which were significantly different from WMTA with expiry date of 2008 and the control group (P < 0.05). At 28- and 60-day intervals, the overall inflammation subsided in all the groups to mild to moderate infiltration of inflammatory cells without any significant differences (P < 0.05)., Conclusion: It seems that the expiry date has less negative effects on the response of inflammatory cells. WMTA keeps its biocompatibility even after expiry date., (© 2011 John Wiley & Sons A/S.)

Objective: To evaluate a novel method of detecting and comparing the porosity of white Mineral Trioxide Aggregate and Portland cement at two different pH., Materials and Methods: Cylindrical specimens (n = 120) were prepared from hydrated ordinary white Portland Cement (WPC) (n = 60) and white Mineral Trioxide Aggregate (WMTA) (n = 60) and exposed to environments with pH of 4.4 (n = 30) or 7.4 (n = 30). The pore size distribution and total pore volume were detected using Mercury Intrusion Porosimetry. Data were analyzed by analysis of variance and post-hoc Tukey or Tamhane test (p = 0.05)., Results: The pore volume of WMTA was significantly lesser than WPC at both pH (p < 0.05). The surface tension of mercury was taken as 480 (N/m) and the contact angle 141.3° for both materials. Pores were consistently found in all specimens. Total pore volumes for WPC and WMTA (cubic centimeter/gram) were 0.1954 and 0.1023, respectively, while the diameter of the pores ranged from 50-100 Å and 20-50 Å, respectively., Conclusions: Mercury Intrusion Porosimetry technique is a promising and reliable technique for assessing the porosity of endodontic materials.

Objectives: One of the most important factors for suitable materials for pulp therapy is biocompatibility. Two histopathologic methods of Cox and Federation Dentaire International (FDI) were used to evaluate inflammation. In Cox method, density of inflammatory cells, tissue reactions like fibrosis, vascular responses like congestion and fibrin extravasation have been used to evaluate inflammatory reactions. The aim of this study was to compare the accuracy of pathologists' interpretations using two different methods., Study Design: Three pathologists observed the degree of inflammation in 225 histopathologic sections. These sections showed inflammation in subcutaneous connective tissue of rats adjacent to polyethylene tubes, filled with white or gray mineral trioxide aggregate. Empty tubes served as controls. Samples were harvested after 7-, 15-, 30-, 60-, and 90-days. All pathologists examined the sections under a light microscope (Carl Zeiss, Oberkochen, Germany) at ×400 magnifications. Chi-Square test was used to evaluate the difference between inflammation grades when one pathologist used two methods. Cohen's Kappa value was used to measure agreement of three pathologists to recognize the degrees of inflammations when using one of the methods., Results: There were no significant differences between the two methods when one of the pathologist used these methods to report the degree of inflammation (p=0.054). However, two other pathologists reported significant differences between two methods (p=0.005, p=0.001). In the FDI method, there was an acceptable agreement between first and second, and first and third pathologist in terms of the degree of inflammation, and intermediate agreement existed between the second and third pathologist. With the Cox method, no agreement among the pathologists could be found., Conclusion: The results of three pathologists in terms of rating inflammation with the FDI method showed better agreement than with the Cox method. Therefore, FDI method is more reliable than the Cox method to evaluate inflammation.

Objectives: There is some evidence that the pH at the root surface is reduced by intracoronal placement of bleaching pastes, which is known to enhance osteoclastic activity. Therefore, it is recommended that a protective barrier be used over the canal filling to prevent leakage of bleaching agents. Glass-ionomer (GI) is commonly used as a coronal barrier before nonvital bleaching. Because mineral trioxide aggregate (MTA) creates high alkalinity after mixing with water, using MTA as a protective barrier over the canal filling may not only prevent leakage of bleaching agents and microorganisms, but may prevent cervical resorption. The aim of this study was to evaluate sealing ability of white mineral trioxide aggregate (WMTA) as a coronal barrier before nonvital bleaching., Study Design: Root canals of one hundred thirty human maxillary incisors were instrumented and filled with gutta-percha without sealer. Gutta-percha was removed up to 3 mm below the cementoenamel junction (CEJ). The teeth were randomly divided into six experimental groups of 20 teeth each and two control groups of 5. In three experimental groups, WMTA was packed into the canal to the level of CEJ. In the remaining experimental groups, glass-ionomer (GI) was used as a coronal barrier. After a 24-hour incubation period, one of the following three bleaching agents was placed in the access cavity of each of the WMTA or GI groups. These three bleaching agents were 30% hydrogen peroxide, sodium perborate mixed with 30% hydrogen peroxide, and sodium perborate mixed with distilled water. The bleaching agents were replaced every 3 days for three times. In the positive controls, no coronal barrier was used. In the negative controls, all the tooth surfaces were covered by two layers of nail varnish. Microleakage was evaluated using protein leakage test. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney tests., Results: The experimental groups showed minimum leakage which was not significantly more than tha in the negative controls. There was no statistically significant difference in leakage between the experimental groups (p<0.05)., Conclusions: This study indicated that different bleaching agents have no effect on sealing ability of WMTA.

Objectives: The aim of this study was to evaluate microleakage of white mineral trioxide aggregate (WMTA) after its exposure to a range of alkaline environments during hydration., Study Design: Seventy single-rooted teeth were divided into 4 experimental and 2 control groups. All the teeth were instrumented, and their apices were resected. Root-end cavities were filled with WMTA in the experimental groups. In the control groups, root-end cavities were not filled. Root-end fillings were exposed to alkaline environments with pH values of 7.4, 8.4, 9.4, or 10.4 for 3 days. Microleakage was evaluated by bovine serum albumin. Evaluations were carried out at 24-hour intervals for 80 days. Data were analyzed by one-way analysis of variance and a post hoc Tukey test at the 0.05 level of confidence., Results: The number of days (mean ± standard deviation) needed for color change at pH values of 7.4, 8.4, 9.4, and 10.4 were 78.53 ± 5.68, 80.00 ± 0.00, 68.93 ± 19.00, and 34.46 ± 12.73, respectively. The time needed for leakage to occur was significantly shorter in samples stored at a pH value of 10.4 (P<0.001)., Conclusions: Within the limits of this study, it can be concluded that pH values greater than 9.4 may jeopardize the sealing ability of WMTA during hydration.

Introduction: The aim of this study was to evaluate the effect of a range of alkaline pH values on the push-out strength of white mineral trioxide aggregate (WMTA)., Methods: The standardized lumens of root slices prepared from extracted single-rooted human teeth were filled with white ProRoot MTA. The specimens were then randomly divided into 4 groups (n = 20) and wrapped in pieces of gauze soaked in synthetic tissue fluid (STF) (pH, 7.4) and STF buffered in potassium hydroxide at pH values of 8.4, 9.4, or 10.4. The samples were incubated for 3 days at 37 °C. The push-out bond strengths were then measured by using a universal testing machine. Failure modes after the push-out test were examined under a light microscope at ×40 magnification. The data were analyzed by using one-way analysis of variance and Tukey post hoc tests., Results: The greatest (9.46 ± 0.63 MPa) and lowest (5.68 ± 0.83 MPa) mean push-out bond strengths were observed after exposure to pH values of 8.4 and 10.4, respectively. There were significant differences between the groups (P = .001). The bond failure was adhesive for all experimental groups., Conclusions: Push-out bond strength of WMTA could be influenced by different alkaline pH values., (Copyright © 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Storage temperature influences the properties of Portland cement during mixing. Because of similarities between Portland cement and mineral trioxide aggregate, the aim of the present study was to evaluate surface microhardness, topography, and phase structure of white mineral trioxide aggregate (WMTA) after storage in a range of temperatures., Methods: Thirty WMTA sachets were divided into 3 groups of 10. The 3 groups were stored at 4 degrees C, 25 degrees C, and 40 degrees C for 48 hours with accompanying ampules. Sachets were immediately mixed after removal from storage according to manufacturer's instructions and mixed and packed into cylindrical glass tubes at room temperature. Surface microhardness of each specimen was measured after 3 days. Four specimens from each group were prepared and observed under scanning electron microscope and x-ray diffraction. Data were subjected to one-way analysis of variance and a post hoc Tukey test at P <.05., Results: Mean surface hardness +/- standard deviation after storage at 4 degrees C, 25 degrees C, and 40 degrees C were 25.23 +/- 5.99, 53.56 +/- 3.28, and 62.89 +/- 1.76, respectively. Statistically significant differences were observed among the groups (P < .001). More voids and a disorganized, flake-like topography were observed in specimens stored at 4 degrees C in comparison with those stored at 25 degrees C and 40 degrees C. X-ray diffraction meter generated similar peaks at 40 degrees C and 25 degrees C, but slight differences were observed at 4 degrees C., Conclusions: This study indicated that storage temperature might influence surface hardness and microstructure of WMTA., (Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this study was subjective evaluation of inflammatory cells subsequent to subcutaneous implantation of white mineral trioxide aggregate (WMTA) mixed with disodium hydrogen phosphate (Na(2)HPO(4)) in rats., Methods: Forty Wistar rats were used in this study. Polyethylene tubes filled with WMTA mixed with Na(2)HPO(4) and WMTA alone and also empty tubes serving as control were implanted into subcutaneous tissue and harvested after 7, 15, 30, and 90 days. Histologic sections were stained with hematoxylin-eosin and observed under a light microscope. Inflammatory reactions were categorized as 0 or none (without inflammatory cells), 1 or mild (inflammatory cells < 25), 2 or moderate (25-125 inflammatory cells), and 3 or severe (more than 125 inflammatory cells). Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney tests., Results: WMTA alone provoked a moderate inflammatory reaction after 7 and 15 days, which significantly differed from WMTA mixed with Na(2)HPO(4) and the control group, which provoked a mild inflammatory reaction (P < .05). However, there were no significant differences at any period beyond 30 days., Conclusions: This study indicates that adding Na(2)HPO(4) to WMTA creates a more biocompatible material than WMTA alone.

Introduction: The aim of this study was to evaluate morphologic microstructure and surface hardness of white mineral trioxide aggregate (WMTA) after exposure to a range of alkaline environments during hydration., Methods: WMTA was mixed and packed into 60 glass tubes. Four groups, each containing 15 tubes, were exposed to pH values of 7.4, 8.4, 9.4, and 10.4, respectively, for 3 days. In 12 tubes in each group, Vickers surface hardness was measured after exposure to alkaline environments. Data were subjected to one-way analysis of variance and a post hoc Tukey test. Three specimens in each group were prepared to be evaluated under a scanning electron microscope using scattered electron (SE) and backscattered electron (BSE) detectors., Results: The mean surface hardness values +/- standard deviation after exposure to pH values of 7.4, 8.4, 9.4, and 10.4 were 58.28 +/- 8.21, 68.84 +/- 7.19, 67.32 +/- 7.22, and 59.22 +/- 9.14, respectively. The difference between these values was statistically significant (p = 0.000). There were statistically significant differences between pH values of 8.4 and 9.4 and pH values of 7.4 and 10.4 (p > 0.05). The SE detector revealed needle-shaped crystals at pH values of 7.4 and 8.4 and an amorphous microstructure at pH values of 9.4 and 10.4 on WMTA surface. The BSE detector showed more unhydrated structure and pores at pH values of 7.4 and 10.4 compared with pH values of 8.4 and 9.4., Conclusions: Surface hardness can be influenced by different alkaline pH values. The BSE detector can reveal more microstructure details of WMTA in conjunction with the SE detector. More porosity and unhydrated structure are observed in WMTA exposed to pH values of 7.4 and 10.4.

The aim of the present study was to evaluate microleakage of mineral trioxide aggregate (MTA) used as a root-end filling material after its exposure to a range of acidic environments during hydration. Seventy single-rooted teeth were divided into 4 experimental and 2 control groups. All the teeth were instrumented, and their apices were resected. Root-end cavities were filled with white MTA in the experimental groups. In the control groups root-end cavities were not filled. Root-end fillings were exposed to acidic environments with pH values of 4.4, 5.4, 6.4, or 7.4 for 3 days in the experimental groups. Microleakage was evaluated by using bovine serum albumin. The evaluation was conducted at 24-hour intervals for 80 days. Data were analyzed by using one-way analysis of variance and a post hoc Tukey test. The earliest bovine serum albumin microleakage was observed in a pH value of 4.4 followed by pH values of 5.4, 6.4, and 7.4, respectively. There was a significantly longer time necessary for leakage to occur in samples stored in higher pH values (P < .000).

The aim of this study was to compare the microleakage at three different thicknesses of mineral trioxide aggregate (MTA) as a root-end filling material. Ninety extracted human maxillary incisor teeth were selected and the root canals of the teeth were cleaned, shaped and obturated with gutta percha and AH-plus sealer. Teeth were randomly divided into 3 groups each containing 20 experimental samples, and 5 positive and 5 negative controls. In the first, second and third experimental groups, cavities of 1 mm, 2 mm and 3 mm in depth, respectively, were prepared and filled with MTA. Leakage was determined by the dye penetration method using India ink, and a stereomicroscope at x16 magnifications and 0.1 mm accuracy. The microleakage in the 3-mm and 2-mm root-end cavities was less than at 1 mm depth, but analysis of variance revealed no significant differences among the three different thicknesses.

The aim of this investigation was to compare the quantity of inflammatory cells in response to white and gray mineral trioxide aggregate (MTA) in subcutaneous connective tissue of rats. Fifty Wistar rats were used in this study. Polyethylene tubes were filled with gray or white MTA and empty ones serving as the control group were implanted into subcutaneous tissue and harvested after 7-, 15-, 30-, 60-, and 90-day intervals. Sections of 5 microm were stained with hematoxylin and eosin and observed under a light microscope. Inflammatory reactions were categorized as 0, none (without inflammatory cells); 1, mild (inflammatory cells < or = 25); 2, moderate (25-125 inflammatory cells); and 3, severe (more than 125 inflammatory cells). Statistical analysis was performed with the Kruskal-Wallis test. Both kinds of MTA provoked severe inflammatory reaction after 7 days, which significantly differed from control group (p < 0.05). However, there were no significant differences at any time period beyond 15 days (p > 0.05).

The purpose of this study was to compare the biocompatibility of amalgam, gray MTA and white MTA in the connective tissue of rats. We used 45 Sprague-Dawley rats in this study. The rats were divided into three groups. Root end filling materials were placed in polyethylene tubes and inserted into the rats' connective tissue through incisions. The rats were sacrificed after 3 days, 1 wk, and 3 wk, respectively. Histologic samples were sectioned in 5-mum thicknesses and stained with hematoxylin and eosin. Kruskal-Wallis test was used for statistical analysis. The results showed that after 3 days, white MTA was more biocompatible than gray MTA and amalgam. After 1 week, gray MTA was more biocompatible than white MTA and Amalgam. After 3 wk, there were no significant differences between experimental groups and the control group.