Chemical and physical surface and bulk material characterization of white ProRoot MTA and two Portland cements

Effects of various mixing techniques on physical properties of white mineral trioxide aggregate

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.

Interferometric microscopy study of the surface roughness of Portland cement under the action of different irrigants

Objectives: Some investigations suggested common Portland cement (PC) as a substitute material for MTA for endodontic use; both MTA and PC have a similar composition. The aim of this study was to determine the surface roughness of common PC before and after the exposition to different endodontic irrigating solutions: 10% and 20% citric acid, 17% ethylenediaminetetraacetic (EDTA) and 5% sodium hypochlorite. Study Design: Fifty PC samples in the form of cubes were prepared. PC was mixed with distilled water (powder/liquid ratio 3:1 by weight). The samples were immersed for one minute in 10% and 20% citric acid, 17% EDTA and 5% sodium hypochlorite. After gold coating, PC samples were examined using the New View 100 Zygo interferometric microscope. It was used to examine and register the surface roughness and the profile of two different areas of each sample. Analysis of variance (ANOVA) was carried out, and as the requirements were not met, use was made of the Kruskal-Wallis test for analysis of the results obtained, followed by contrasts using Tukey’s contrast tests. Results: Sodium hypochlorite at a concentration of 5% significantly reduced the surface roughness of PC, while 20% citric acid significantly increased surface roughness. The other evaluated citric acid concentration (10%) slightly increased the surface roughness of PC, though statistical significance was not reached. EDTA at a concentration of 17% failed to modify PC surface roughness. Irrigation with 5% sodium hypochlorite and 20% citric acid lowered and raised the roughness values, respectively. Conclusions: The surface texture of PC is modified as the result of treatment with different irrigating solutions commonly used in endodontics, depending on their chemical composition and concentration.

Key words:MTA, Portland cement, citric acid, ethylenediaminetetraacetic acid, sodium hypochlorite, surface roughness.

The impact of thermocycling process on the dislodgement force of different endodontic cements

To evaluate the effects of thermocycling (500 cycles, 5°C/55°C) on the push-out bond strength of calcium silicate based cements including WMTA, Nano-WMTA, and Bioaggregate to root dentin. Forty-eight dentin slices were prepared and divided into 3 groups (n = 16) and filled with Angelus WMTA, Nano-WMTA, or Bioaggregate. After incubation, half of the samples were thermocycled while the other half remained untreated. Push-out bond strength was calculated, and the modes of the bond failures were determined by SEM. The highest bond strength was seen in nonthermocycled Nano-WMTA samples and the lowest in thermocycled Bioaggregate samples. The significant differences between nonthermocycled and thermocycled samples were only noticed in WMTA and Nano-WMTA groups (P < 0.001). The mode of failure for thermocycled samples of all three cements was mostly cohesive. Thermocycling process can drastically affect the push-out bond strength of calcium silicate based cements. The intrastructural damages occurred due to the thermal stresses, causing cohesive failures in set materials. Sealing property of endodontic cements which have experienced the thermal stresses can be jeopardized due to occlusal forces happening in furcation cites.

Effect of MTA and Portland Cement on Fracture Resistance of Dentin

Background and aims. It is important to evaluate the effects of endodontic materials on tooth structures to avoid endodontic treatment failure. The aim of the present study was to investigate the effect of mineral trioxide aggregates (MTA) and Portland cement (PC) on fracture resistance of dentin.

Materials and methods. Thirty-six freshly extracted human single-rooted premolar teeth were selected. The crowns were removed and the roots were randomly divided into two experimental groups and one control group. The root samples were longitudinally divided into two halves and a dentin bar (2×2×10 mm) was cut from each root section for short-term (2weeks) and long-term (12 weeks) evaluations. The root sections in the experimental groups were exposed to MTA or PC, while keeping the control group specimens in physiologic saline. The fracture resistance of each specimen was measured using an Instron testing machine. The results were statistically analyzed using ANOVA, a post hoc Tukey test and paired t-test at 5% significance level.

Results. The fracture resistance of MTA-treated specimens significantly increased between 2 and 12 weeks (P<0.05). After 12 weeks, MTA-treated specimens had the highest fracture resistance. In the PC group, the fracture resistance of specimens did not change significantly over time (P>0.05).

Conclusion. The results showed that MTA increased the fracture resistance of root dentin, while PC had no significant effect on dentin fracture resistance.

Influence of light and oxygen on the color stability of five calcium silicate-based materials

INTRODUCTION

Difficult handling, long setting time, and potential discoloration are important drawbacks of white mineral trioxide aggregate (WMTA). The development of Biodentine, a recently developed calcium silicate-based material (CSM), has overcome some of these shortcomings; however, there are no available data on its color stability. A previous study showed that WMTA discolors under light irradiation in an oxygen-free environment. The present study evaluated the influence of light irradiation and oxygen on the color stability of 5 CSMs.

METHODS

Fifteen samples of 5 CSMs (ProRoot WMTA, Angelus WMTA, White Portland Cement [PC], PC with bismuth oxide, and Biodentine) were divided into 5 groups. Each group was exposed to different oxygen and light conditions. A spectrophotometer was used to determine the color of each specimen at 0, 120 seconds, and 5 days. Data were analyzed by using analysis of variance and Tukey honestly significant difference test.

RESULTS

The materials PC with bismuth oxide, Angelus WMTA, and ProRoot WMTA showed dark discoloration after light irradiation in an oxygen-free environment, which was statistically significantly different from Biodentine and PC. In groups that were exposed to no light irradiation or to an oxygen atmosphere, all materials showed color stability over time, and no significant differences were observed among them. PC and Biodentine maintained color stability in all conditions over time and showed no significant differences.

CONCLUSIONS

The combination of light and anaerobic conditions (similar to those in clinical situations) results in differences in color of the tested CSMs during a period of 5 days, of which Biodentine and PC demonstrated color stability.

Chemical characteristics of mineral trioxide aggregate and its hydration reaction

Mineral trioxide aggregate (MTA) was developed in early 1990s and has been successfully used for root perforation repair, root end filling, and one-visit apexification. MTA is composed mainly of tricalcium silicate and dicalcium silicate. When MTA is hydrated, calcium silicate hydrate (CSH) and calcium hydroxide is formed. Formed calcium hydroxide interacts with the phosphate ion in body fluid and form amorphous calcium phosphate (ACP) which finally transforms into calcium deficient hydroxyapatite (CDHA). These mineral precipitate were reported to form the MTA-dentin interfacial layer which enhances the sealing ability of MTA. Clinically, the use of zinc oxide euginol (ZOE) based materials may retard the setting of MTA. Also, the use of acids or contact with excessive blood should be avoided before complete set of MTA, because these conditions could adversely affect the hydration reaction of MTA. Further studies on the chemical nature of MTA hydration reaction are needed.

Bond strength of adhesive systems to mineral trioxide aggregate with different time intervals

INTRODUCTION

The aim of this study was to compare the shear bond strengths of various adhesive systems to white mineral trioxide aggregate (WMTA) with different time intervals.

METHODS

Two hundred cylindrical acrylic blocks with a hole (4-mm diameter and 2-mm height) were prepared. The holes were filled with WMTA, and the specimens were allocated into 5 groups. Forty specimens were stored for 4, 24, 48, 72, and 96 hours at 37°C and 100% humidity. Each group was divided into 4 subgroups: group 1, All-Bond SE (Bisco Inc, Schaumburg, IL); group 2, All-Bond 3 (Bisco Inc); group 3, One-Step Plus (Bisco Inc); and group 4, control. After the application of adhesive systems, composite resin (Aelite, Bisco) was applied over the WMTA. Shear bond strengths were measured using a universal testing machine, and the data were subjected to 1-way analysis of variance and the Scheffé post hoc test.

RESULTS

There was a significant difference between the 4-, 24-, 48-, 72-, and 96-hour measurements in all of the adhesive systems (P < .001). Among all time intervals, group 3 showed significantly higher bond strengths to WMTA than the other groups (P < .001). Groups 1 and 2 were similar (P = .365).

CONCLUSIONS

It was concluded that if a longer waiting time can be practiced after the mixing of WMTA, higher shear bond strength measurements can be obtained. Also, when WMTA was used with total-etch adhesive systems, it showed better shear bond strength.

Effect of Synthetic Tissue Fluid on Microleakage of Grey and White Mineral Trioxide Aggregate as Root-End Filling Materials: An in vitro study

OBJECTIVES

The success of endodontic surgery has been shown to depend partly on the apical seal. Grey mineral trioxide aggregate (GMTA) produces hydroxyapatite twice as often as white mineral trioxide aggregate (WMTA) when suspended in a phosphate buffered saline (PBS) solution. The aim of this in vitro study was to compare the microleakage phenomenon of gray and white mineral trioxide aggregates as root-end filling materials after immersion in synthetic tissue fluid (STF).

METHODS

55 single-rooted extracted maxillary anterior human teeth were divided into two experimental groups of 20 teeth each, plus 3 groups of 5 teeth each as two negative and one positive control groups. The root canals were cleaned, shaped, and laterally compacted with gutta-percha. The root ends were resected and 3 mm deep cavities were prepared. The root-end preparations were filled with GMTA or WMTA in the experimental groups. Leakage was determined using a dye penetration method. Data were analysed using analysis of variance (ANOVA) at the 0.05 level of significance.

RESULTS

The mean dye leakage was 0.40 ± 0.1 mm for GMTA and 0.50±0.1 mm for WMTA groups, respectively. There was no significant difference between the two experimental groups (P = 0.14).

CONCLUSION

Despite the different properties and behaviours of GMTA and WMTA in STF, there were no significant differences in microleakage when using GMTA or WMTA.

Characteristics of novel root-end filling material using epoxy resin and Portland cement

OBJECTIVES

The aim of this study was to evaluate the physical properties and cytotoxicity of a novel root-end filling material (EPC) which is made from epoxy resin and Portland cement as a mineral trioxide aggregate (MTA) substitute.

MATERIALS AND METHODS

EPC, developed as a root-end filling material, was compared with MTA and a mixture of AH Plus sealer and MTA (AMTA) with regard to the setting time, radio-opacity, and microleakage. Setting times were evaluated using Vicat apparatus. Digital radiographs were taken to evaluate the aluminium equivalent radio-opacity using an aluminium step wedge. Extracted single-rooted teeth were used for leakage test using methylene blue dye. After canal shaping and obturation, the apical 3-mm root was resected, and a root-end cavity with a depth of 3 mm was prepared. The root-end cavities were filled with MTA, AMTA, and EPC for 15 specimens in each of three groups. After setting in humid conditions for 24 h, the specimens were tested for apical leakage. For evaluation of the biocompatibility of EPC, cell (human gingival fibroblast) viability was compared for MTA and Portland cement by MTT assay, and cell morphological changes were compared for MTA and AH Plus by fluorescence microscopy using DAPI and F-actin staining. The setting time, radio-opacity, and microleakage were compared using one-way ANOVA and Scheffe's post hoc comparison, and the cytotoxicity was compared using the nonparametric Kruskal-Wallis rank sum test. Statistical significance was set at 95%.

RESULTS

EPC had a shorter setting time and less microleakage compared with MTA (p < 0.05). EPC showed 5-mm aluminium thickness radio-opacity and similar biocompatibility to MTA.

CONCLUSIONS

Under the conditions of this study, EPC, a novel composite made from a mixture of epoxy resin and Portland cement, was found to be a useful material for root-end filling, with favourable radio-opacity, short setting time, low microleakage, and clinically acceptable low cytotoxicity.

CLINICAL RELEVANCE

The novel root-end filling material would be a potentially useful material for a surgical endodontic procedure with favourable properties.

Analysis of six heavy metals in Ortho mineral trioxide aggregate and ProRoot mineral trioxide aggregate by inductively coupled plasma-optical emission spectrometry

Ortho mineral trioxide aggregate (MTA) is a mineral aggregate newly developed for perforation repair, root end filling and pulp capping. The aim of this study was to investigate the levels of cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn) in Ortho MTA and ProRoot MTA. A total of 0.2 g of each MTA was digested using a mixture of hydrochloric and nitric acids and filtered. Six heavy metals in the resulting filtrates were analyzed by inductively coupled plasma-optical emission spectrometry (n = 5). The results were statistically analyzed using the Mann-Whitney U-test. The concentrations of Cd, Cu, Fe, Mn, Ni and Zn in Ortho MTA were 0.10, 7.73, 49.51, 2.58, 0.82 and 10.09 p.p.m., respectively. The concentrations of Cd, Cu, Fe, Mn, Ni and Zn in ProRoot MTA were 0.16, 9.38, 1438.11, 74.51, 18.98 and 4.05 p.p.m., respectively. In conclusion, Ortho MTA had lower levels of Cd, Cu, Fe, Mn and Ni than ProRoot MTA.

Characterization and analyses of acid-extractable and leached trace elements in dental cements

AIMS

Determination of the elemental constitution and investigation of the total and leachable arsenic, chromium and lead in Portland cement, pure tricalcium silicate, Biodentine, Bioaggregate and mineral trioxide aggregate (MTA) Angelus.

METHODOLOGY

The chemical composition of Portland cement, MTA Angelus, tricalcium silicate cement, Biodentine and Bioaggregate was determined using X-ray fluorescence (XRF). Measurements of arsenic, lead and chromium were taken with inductively coupled plasma-mass spectrometry (ICP-MS), following acid digestion on the hydrated material and on leachates of cements soaked in Hank's balanced salt solution (HBSS).

RESULTS

All the cements investigated had a similar oxide composition with the main oxide being calcium and silicon oxide. Both the Portland cement and MTA Angelus had an additional aluminium oxide. The dental cements included a radiopacifying material. All the materials tested had higher acid-extractable arsenic content than the level set by ISO 9917-1 (2007) and an acceptable level of lead. Regardless these high levels of trace elements present in the materials, the leaching in HBSS was minimal for all the dental material tested in contrast to the high levels displayed by Portland cement.

CONCLUSIONS

Dental materials based on tricalcium silicate cement and MTA Angelus release minimal quantities of trace elements when in contact with simulated body fluids. The results of acid extraction could be affected by nonspecific matrix effects by the cement.

Effects of simvastain and enamel matrix derivative on Portland cement with bismuth oxide-induced growth and odontoblastic differentiation in human dental pulp cells

INTRODUCTION

We previously reported that bismuth oxide containing Portland cement (BPC) showed similar biocompatibility to Portland cement (PC) in periodontal ligament cells. However, the bioactivity of simvastatin and Emdogain (Biora AB, Malmö, Sweden) on BPC was not reported. The aim of this study was to evaluate the effects of simvastatin and Emdogain on BPC compared with mineral trioxide aggregate (MTA) in human dental pulp cells (HDPCs).

METHODS

Cell growth was determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) assay. Differentiation was evaluated by alkaline phosphatase (ALP) activity, alizarin red staining, and reverse-transcriptase polymerase chain reaction.

RESULTS

The cell growth of HDPCs exposed to Emdogain and simvastatin plus BPC was superior to those administered BPC alone and similar to those that received MTA for 14 days. The simvastatin and Emdogain groups increased the odontogenic potential of the BPC group with respect to ALP activity, mineralization nodules, messenger RNA expression of ALP, osteopontin, osteocalcin, Runx2, and osterix.

CONCLUSIONS

These results suggest that simvastatin and Emdogain improved cell growth and the differentiation of the BPC group in HDPCs and may be useful ingredients in BPC as pulp-capping material.

Effects of calcium silicate-based materials on collagen matrix integrity of mineralized dentin

INTRODUCTION

Calcium silicate-based materials (CSMs) are used in various endodontic procedures. The present study examined whether prolonged contact of mineralized dentin with recently commercialized versions of these materials adversely affects dentin collagen matrix integrity.

METHODS

Dentin slabs prepared from extracted human third molars (7 × 3 × 0.3 mm) were divided into 3 groups on the basis of the material to which dentin was exposed (MTA Plus, Biodentine, untreated control dentin slabs) and the time period of exposure (24 hours, 1, 2, and 3 months; n = 6). Hydroxyproline assay was performed on each group's supernatant to quantify the collagen extraction amounts of each group per time period. Data were analyzed with two-factor repeated-measures analysis of variance and Holm-Sidak pair-wise comparisons (α = 0.05) to determine the effects of material and aging time on collagen extraction. Dentin slabs from the 3 months of aging group were demineralized for transmission electron microscopy examination of collagen matrix ultrastructural changes.

RESULTS

Material (P = .002), aging time (P < .001), and their interactions (P = .007) significantly affected the amount of hydroxyproline (pg/mg of mineralized dentin) extracted from mineralized dentin and were significantly correlated by power regression models. Collagen degradation was identified from the surface of dentin slabs that were in direct contact with CSMs.

CONCLUSIONS

Prolonged contact of mineralized dentin with CSMs has an adverse effect on the integrity of the dentin collagen matrix. However, the amount of collagen extracted was limited to the contact surface. Clinicians can continue to apply CSMs in endodontic procedures; however, caution is advised when these materials are applied to thin dentinal walls.

Radiopacity evaluation of Portland and MTA-based cements by digital radiographic system

OBJECTIVE

The aim of the present study was to evaluate the radiopacity of Portland and MTA-based cements using the Digora TM digital radiographic system.

MATERIAL AND METHODS

The performed tests followed specification number 57 from the American National Standard Institute/American Dental Association (2000) for endodontic sealing materials. The materials were placed in 5 acrylic plates, especially designed for this experiment, along with a graduated aluminum stepwedge varying from 1 to 10 mm in thickness. The set was radiographed at a 30 cm focus-object distance and with 0.2 s exposure time. After the radiographs were taken, the optical laser readings of radiographs were performed by Digora TM system. Five radiographic density readings were performed for each studied material and for each step of the aluminum scale.

RESULTS

White ProRoot MTA (155.99±8.04), gray ProRoot MTA (155.96±16.30) and MTA BIO (143.13±16.94) presented higher radiopacity values (p<0.05), while white non-structural Portland (119.76±22.34), gray Portland (109.71±4.90) and white structural Portland (99.59±12.88) presented lower radiopacity values (p<0.05).

CONCLUSIONS

It was concluded that MTA-based cements were the only materials presenting radiopacity within the ANSI/ADA specifications.

White mineral trioxide aggregate pulpotomies: Two case reports with long-term follow-up

This case report describes the partial pulpotomy treatment of complicated crown fractures of two cases by using white mineral trioxide aggregate (WMTA) with long-term follow-up. In the cases presented here, to injured incisor teeth were open apices and the pulp exposure site was large, so it was decided to perform vital pulpotomy with WMTA. Long-term follow-up examinations revealed that the treatment preserved pulpal vitality with continued root development and apex formation. WMTA may be considered as an alternative option for the treatment of traumatized immature permanent teeth.

MTA resorption and periradicular healing in an open-apex incisor: A case report

This case report describes the periradicular healing and resorption of an unintentional extrusion of mineral trioxide aggregate (MTA) in an open-apex central incisor. A 22-year old female with a symptomatic open-apex right maxillary central incisor associated with a periradicular lesion was referred for evaluation and treatment. After chemomechanical debridement, the apical third of the root canal was filled with MTA to create an apical plug. Postoperative radiographs showed the extrusion of MTA into the periradicular lesion. The tooth was then restored with a post and crown. At the 2-year follow-up, the tooth was asymptomatic and radiographs revealed complete healing of the periradicular area. At the 7-year follow-up, complete resorption of the extruded MTA was evident. The results of this case study indicate that complete resorption of extruded MTA is possible in the long term; however, the extrusion of MTA in open-apex tooth should still be avoided.

Uptake of calcium and silicon released from calcium silicate-based endodontic materials into root canal dentine

AIM

To compare Biodentine and White ProRoot mineral trioxide aggregate (MTA) with regard to Ca and Si uptake by adjacent root canal dentine in the presence of phosphate-buffered saline (PBS).

METHODOLOGY

Root canals of bovine incisor root segments were instrumented, filled with either Biodentine or MTA (n = 20 each) and then immersed in Ca-and Mg-free PBS for 1, 7, 30 or 90 days (n = 5 each). Unfilled, unimmersed dentine specimens (n = 5) served as controls. The specimens were sectioned longitudinally, and the ultrastructure of the dentine-material interface and the elemental composition/distribution in the material-adjacent dentine were analysed using a wavelength-dispersive X-ray spectroscopy electron probe microanalyser with image observation function. Data were statistically analyzed using one-way anova and Tukey's honestly significant difference test or the Mann-Whitney U-test.

RESULTS

Along the material-dentine interface, both materials formed a tag-like structure that was composed of either Ca- and P-rich crystalline deposits or the material itself. The width of a Ca- and Si-rich layer detected along the dentine layer of the material-dentine interface showed increases over time. The Ca- and Si-rich layer width was significantly larger (P < 0.05) in Biodentine than MTA at 30 and 90 days.

CONCLUSIONS

Both Biodentine and MTA caused the uptake of Ca and Si in the adjacent root canal dentine in the presence of PBS. The dentine element uptake was more prominent for Biodentine than MTA.

Management of recently traumatized maxillary central incisors by partial pulpotomy using MTA: Case reports with two-year follow-up

In traumatized, young, permanent teeth, pulpotomy is classically undertaken to promote apexogenesis. The objective is to promote root development and apical closure. Once root end development and apical closure is achieved, the root canal treatment is completed. However, it has been suggested that mere pulp exposure does not cause pulpitis in the absence of bacteria. Recent studies have proposed that as long as a good seal is ensured, root canal treatment may not be necessary following pulpotomy. In this article we report two cases of traumatized, fully matured, maxillary permanent central incisors, which have been treated with mineral trioxide aggregate following partial pulpotomy, with a two-year follow-up.

Setting properties and biocompatibility of dicalcium silicate with varying additions of tricalcium aluminate

This study sought to prepare biphasic mixtures by adding tricalcium aluminate (Ca3Al2O6) into dicalcium silicate (Ca2SiO4) and to evaluate the effect of Ca3Al2O6 on setting properties and biocompatibility of the Ca2SiO4/Ca3Al2O6 mixtures as compared to pure Ca2SiO4. The results indicated that the addition of Ca3Al2O6 into Ca2SiO4 reduced the setting time and improved the compressive strength. Furthermore, Ca2SiO4/Ca3Al2O6 mixtures were bioactive and biocompatible, and had a stimulatory effect on the L929 cell growth when the content of Ca3Al2O6 was below 10%. Therefore, the mixtures with 10% Ca3Al2O6 produced the best compromise between setting and in vitro biological properties.

Effect of selected accelerants on setting time and biocompatibility of mineral trioxide aggregate (MTA)

OBJECTIVE

Various additives have been suggested to be used with mineral trioxide aggregate (MTA) to improve its handling characteristics. The purpose of this study was to evaluate the effects of various additives on setting time and cell attachment on gray MTA (GMTA).

STUDY DESIGN

Single-rooted caries-free teeth were split, and dentin disks with class I cavity were made and filled with test and control materials. Setting time was measured using Gilmore apparatus. Mouse MC3T3-E1 osteoblasts and L929 mouse fibroblasts were grown on dentin and GMTA disks. Cell attachment was examined under fluorescent microscope.

RESULTS

Adding KY liquid, CaCl(2), and NaOCl to GMTA improved the handling properties and decreased setting time. Osteoblasts and fibroblasts attached and spread on GMTA mixed with additives in a manner similar to GMTA mixed with water.

CONCLUSIONS

The various additives could be possible substitutes to water to decrease MTA setting time. MTA is biocompatible when mixed with the various additives.

Endodontic essay

"It has been said that Mineral Trioxide Aggregate is driving an endodontic revolution. Discuss this statement considering the biological and clinical attributes of this innovative material."

"MTA"-an Hydraulic Silicate Cement: review update and setting reaction

OBJECTIVES

To review the current status and understanding of Portland cement-like endodontic materials commonly referred to by the trade designation "MTA" (alias "Mineral Trioxide Aggregate"), and to present an outline setting reaction scheme, hitherto unattempted.

METHOD

The literature was searched using on-line tools, overlapping an earlier substantial review to pick up any omissions, including that in respect of ordinary Portland cement (OPC), with which MTA shares much. The search was conducted for the period January 2005 to December 2009 using 'MTA', 'GMTA', 'WMTA', and 'mineral AND trioxide AND aggregate' as keywords, with various on-line search engines including ScienceDirect (http://www.sciencedirect.com), SAGE Journals Online (http://online.sagepub.com), Wiley Online Library (http://onlinelibrary.wiley.com), SciELO Scientific electronic library online (http://www.scielo.br/scielo.php), JSTOR (http://www.jstor.org), and Scopus (http://www.scopus.com). References of articles found were cross-checked where appropriate for missed publications. Manufacturers' and related websites were searched with Google Search (http://www.google.com.hk).

RESULTS

A generic name for this class of materials, Hydraulic Silicate Cement (HSC), is proposed, and an outline reaction scheme has been deduced. HSC has distinct advantages apparent, including sealing, sterilizing, mineralizing, dentinogenic and osteogenic capacities, which research continues to demonstrate. However, ad hoc modifications have little supporting justification.

SIGNIFICANCE

While HSC has a definite place in dentistry, with few of the drawbacks associated with other materials, some improvements in handling and other properties are highly desirable, as are studies of the mechanisms of the several beneficial physiological effects. Reference to the extensive, but complex, literature on OPC may provide the necessary insight.

Effect of tricalcium aluminate on the properties of tricalcium silicate-tricalcium aluminate mixtures: setting time, mechanical strength and biocompatibility

AIM

To prepare biphasic mixtures by adding Ca(3) Al(2) O(6) into Ca(3) SiO(5) and to evaluate the effect of Ca(3) Al(2) O(6) on physical and ex vivo biological properties of the Ca(3) SiO(5) /Ca(3) Al(2) O(6) mixtures derived from mineral trioxide aggregate (MTA).

METHODOLOGY

Combinations of Ca(3) SiO(5) and Ca(3) Al(2) O(6) (0, 5%, 10% and 15%) powders were mixed with deionized water. After hydration, setting time, compressive strength, ex vivo bioactivity and biocompatibility of each mixture were investigated and compared to pure Ca(3) SiO(5) .

RESULTS

With the addition of Ca(3) Al(2) O(6) from 0% to 15%, the initial setting time and final setting time of the Ca(3) SiO(5) /Ca(3) Al(2) O(6) mixtures decreased from 110 to 43min and from 220 to 97min, respectively (P≤0.05). However, the compressive strength increased from 6.75 to 16.20MPa after one day (P≤0.05) and from 17.73 to 29.13 Mpa after 28 days. Furthermore, the mixtures with 10% Ca(3) Al(2) O(6) or less had similar bioactivity and biocompatibility when compared to the pure Ca(3) SiO(5).

CONCLUSIONS

The addition of Ca(3) Al(2) O(6) into Ca(3) SiO(5) accelerated the hydration process, reduced the setting time and improved the compressive strength. Furthermore, these mixtures were bioactive and biocompatible and had a stimulatory effect on the L929 cell growth when the content of Ca(3) Al(2) O(6) was below 10%. Therefore, the mixtures with 10% Ca(3) Al(2) O(6) produced the best compromise between hydration and ex vivo biological properties.

Effect of mineral trioxide aggregates and Portland cements on inflammatory cells

INTRODUCTION

Recently, some studies have compared mineral trioxide aggregate (MTA) with Portland cements, concluding that the principal ingredients of Portland cements are similar to those of MTA. The purpose of the present study was to evaluate the effect of gray MTA, white MTA, and gray and white Portland cements on inflammatory cells in rats.

METHODS

Fresh mixtures mixed with distilled water were placed in polyethylene tubes, which were implanted in the dorsal subcutaneous connective tissue of 60 Sprague-Dawley rats along with empty tubes as controls. Tissue specimens were collected after the rats were sacrificed after 7, 15, 30, 60, and 90 days. The specimens were fixed, stained, processed, and histologically evaluated under a light microscope. Inflammatory reactions were classified as grade 0: without inflammatory cells, grade I: sporadic infiltration of inflammatory cells, grade II: moderate infiltration (<25 cells), grade III: dense and severe infiltration (25-125 cells), and grade IV: very dense and severe infiltration (>125 cells). Data were analyzed with the nonparametric (two factor) analysis of variance and Kruskal-Wallis H-test.

RESULTS

All the groups showed grade III inflammation after 7 and 15 days; there was a decrease in the inflammatory process after 30, 60, and 90 days. After 90 days, gray MTA, white MTA, and control groups had grade 0 inflammatory process, but gray Portland cement and white Portland cement groups showed grade 0 to grade I inflammatory processes.

CONCLUSION

MTAs were more biocompatible; however, more studies are required.

Cytotoxicity and biocompatibility of direct and indirect pulp capping materials

There are several studies about the cytotoxic effects of dental materials in contact with the pulp tissue, such as calcium hydroxide (CH), adhesive systems, resin composite and glass ionomer cements. The aim of this review article was to summarize and discuss the cytotoxicity and biocompatibility of materials used for protection of the dentin-pulp complex, some components of resin composites and adhesive systems when placed in direct or indirect contact with the pulp tissue. A large number of dental materials present cytotoxic effects when applied close or directly to the pulp, and the only material that seems to stimulate early pulp repair and dentin hard tissue barrier formation is CH.

Direct pulp capping with mineral trioxide aggregate: an immunohistologic comparison with calcium hydroxide in rodents

INTRODUCTION

The aim was to evaluate the proliferation of pulp cells 1, 3, and 7 days after direct pulp capping with ProRoot MTA (MTA) and to compare the results with calcium hydroxide (Ca(OH)(2)).

METHODS

An occlusal cavity was prepared in 36 molar teeth of 18 Wistar rats. Then MTA or Ca(OH)(2) was placed on the exposed pulp. All cavities were restored with composite. After 1, 3, and 7 days the animals were killed. One hour before scarification 5-bromo-2'-deoxyuridine (BrdU) was injected into the intraperitoneal cavity for immunohistologic analysis. BrdU was incorporated into the cell nucleus during the S phase of the cell cycle. Proliferating cells were tagged and counted by using alkaline phosphatase and anti-alkaline phosphatase antibody staining. Three animals (6 molar teeth) served as controls and were not further treated. The number of the tagged cells was statistically analyzed by comparing the results of the 3 groups. A Bonferroni correction was performed, because the data of the Ca(OH)(2)- group was used 3 times for pairwise comparison.

RESULTS

The marked cells were identified as fibroblasts, endothelial cells (after 1, 3, and 7 days), and Höhl cells (after 7 days). The MTA group showed a similar amount of Höhl cells when compared with the Ca(OH)(2) group (P > .05). One day and 7 days after capping, no significant differences were observed between the 2 tested groups and the controls (P > .05). After 3 days, significantly more cells were stained in the MTA and Ca(OH)(2) groups than in the control group (P < .016).

CONCLUSIONS

Immunohistologic analysis demonstrated that MTA showed similar results when compared with Ca(OH)(2) within the first week after direct pulp capping.