The Effect of Mineral Trioxide Aggregate on the Mineralization Ability of Rat Dental Pulp Cells: An In Vitro Study

Mineral trioxide aggregate-based endodontic sealer stimulates hydroxyapatite nucleation in human osteoblast-like cell culture

INTRODUCTION

The main purpose of this study was to evaluate the biocompatibility and bioactivity of a new mineral trioxide aggregate (MTA)-based endodontic sealer, MTA Fillapex (MTA-F; Angelus, Londrina, Brazil), in human cell culture.

METHODS

Human osteoblast-like cells (Saos-2) were exposed for 1, 2, 3, and 7 days to MTA-F, Epiphany SE (EP-SE; SybronEndo, Orange, CA), and zinc oxide-eugenol sealer (ZOE). Unexposed cultures were the control group (CT). The viability of the cells was assessed by MTT assay and the morphology by scanning electron microscopy (SEM). The bioactivity of MTA-F was evaluated by alkaline phosphatase activity (ALP) and the detection of calcium deposits in the culture with alizarin red stain (ARS). Energy-dispersive X-ray spectroscopy (EDS) was used to chemically characterize the hydroxyapatite crystallites (HAP). Saos-2 cells were cultured for 21 days for ARS and SEM/EDS. ARS results were expressed as the number of stained nodules per area. Statistical analysis was performed with analysis of variance and Bonferroni tests (P < .01).

RESULTS

MTA-F exposure for 1, 2, and 3 days resulted in increased cytotoxicity. In contrast, viability increased after 7 days of exposure to MTA-F. Exposure to EP-SE and ZOE was cytotoxic at all time points. At day 7, ALP activity increase was significant in the MTA-F group. MTA-F presented the highest percentage of ARS-stained nodules (MTA-F > CT > EP-SE > ZOE). SEM/EDS analysis showed hydroxyapatite crystals only in the MTA-F and CT groups. In the MTA-F group, crystallite morphology and chemical composition were different from CT.

CONCLUSIONS

After setting, the cytotoxicity of MTA-F decreases and the sealer presents suitable bioactivity to stimulate HAP crystal nucleation.

Evaluation of mineral trioxide aggregate (MTA) versus calcium hydroxide cement (Dycal(®) ) in the formation of a dentine bridge: a randomised controlled trial

AIM

To assess the effectiveness of mineral trioxide aggregate (MTA) used as an indirect pulp-capping material in human molar and premolar teeth.

METHODOLOGY

We conducted a clinical evaluation of 60 teeth, which underwent an indirect pulp-capping procedure with either MTA or calcium hydroxide cement (Dycal(®) ). Calcium hydroxide was compared with MTA and the thickness of the newly formed dentine was measured at regular time intervals. The follow-up was at 3 and 6 months, and dentine formation was monitored by radiological measurements on digitised images using Mesurim Pro(®) software.

RESULTS

At 3 months, the clinical success rates of MTA and calcium hydroxide were 93% and 73%, respectively (P = 0.02). At 6 months, the success rate was 89.6% with MTA, and remained steady at 73% with calcium hydroxide (P = 0.63). The mean initial residual dentine thickness was 0.23 mm, and increased by 0.121 mm with MTA and by 0.136 mm with calcium hydroxide at 3 months. At 6 months, there was an increase of 0.235 mm with MTA and of 0.221 mm with calcium hydroxide.

CONCLUSIONS

  A higher success rate was observed in the MTA group relative to the Dycal(®) group after 3 months, which was statistically significant. After 6 months, no statistically significant difference was found in the dentine thickness between the two groups. Additional histological investigations are needed to support these findings.

Effect of dental materials calcium hydroxide-containing cement, mineral trioxide aggregate, and enamel matrix derivative on proliferation and differentiation of human tooth germ stem cells

INTRODUCTION

Biocompatibility of pulp capping materials is important for successful use in dentistry. These materials should be nontoxic and permissive for proliferation and induction of odontogenic differentiation of pulp cells. The aim of our study was to evaluate the effects of enamel matrix derivative (EMD), mineral trioxide aggregate (MTA), and calcium hydroxide-containing cement (DYCAL) on proliferation and odontogenic differentiation of human tooth germ stem cells (hTGSCs) in which cells belonging to both pulp tissue and dental follicle exist.

METHODS

The 96-well plates, 24-well plates, and special chamber slides were coated with biomaterials for cell proliferation, differentiation, and scanning electron microscopy analysis. Odontogenic differentiation of hTGSCs was evaluated by analyzing mRNA expression of dentin sialophosphoprotein (DSPP) by real-time polymerase chain reaction expression analysis, measurement of alkaline phosphatase activity, and visualization of calcium depositions by von Kossa staining.

RESULTS

Our results demonstrate that EMD is the best material in terms of inducing differentiation and proliferation of hTGSCs. DYCAL was found to be toxic to hTGSCs; however, EMD-coated DYCAL showed less toxicity. EMD-coated MTA was not efficient at inducing proliferation and differentiation.

CONCLUSIONS

Pulp capping materials come in direct contact with dental pulp cells; thus, they require comprehensive evaluation of interactions between cells and biomaterials. Therefore, we cultured hTGSCs, capable of odontogenic differentiation, on pulp capping materials directly. Our results suggest that combination of capping materials with EMD would increase the quality of capping by increasing biocompatibility of capping materials.

"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.

Effects of mineral trioxide aggregate on the differentiation of rat dental pulp cells

The effect of mineral trioxide aggregate (MTA) on the odontoblast-like differentiation of pulp cells was evaluated using heat-shock protein 25 (hsp25) as a marker for odontoblast differentiation. The cells were cultured with tooth-colored MTA or calcium hydroxide-containing cement (Dycal). The effects of the materials on the pulp cells were observed using a confocal laser scanning microscope. The cells were labelled immunocytochemically using polyclonal antibodies against hsp25 and actin. The mRNA expression of hsp25 and dspp in the pulp cells at 2 days were examined by quantitative reverse transcription-polymerase chain reaction (RT-PCR). Most of the cells cultured with MTA showed an intense immunolabelling for hsp25 and the mRNA expressions of hsp25 and dspp at 2 days were higher than those cultured with Dycal. These findings indicate that MTA is an effective pulp capping material and is able to induce the differentiation of odontoblast-like cells and the formation of reparative tertiary dentin with minimum apoptosis.

Acemannan, an extracted product from Aloe vera, stimulates dental pulp cell proliferation, differentiation, mineralization, and dentin formation

This study investigated the effect of acemannan (Aloe vera gel polysaccharide) on dentin formation. Primary human dental pulp cells were treated with acemannan. New DNA synthesis, bone morphogenetic protein-2, alkaline phosphatase activity, dentin sialoprotein expression, and mineralization were determined by [(3)H]-thymidine incorporation, enzyme-linked immunosorbent assay, biochemical assay, western blotting, and Alizarin Red staining, respectively. Then the upper first molars of 24 male Sprague Dawley rats were intentionally exposed and capped with either acemannan or calcium hydroxide. At day 28, the teeth were histopathologically examined and evaluated for the degree of inflammation, dentin bridge formation, and pulp tissue organization. The results revealed that acemannan significantly increased pulp cell proliferation, bone morphogenetic protein-2, alkaline phosphatase activity, dentin sialoprotein expression, and mineralization, compared with the untreated group. The acemannan-treated group also exhibited a complete homogeneous calcified dentin bridge and good pulp tissue organization, whereas neither was detected in the calcium hydroxide-treated and sham groups. In the acemannan-treated group, either mild or no inflammation was found, whereas the other groups had various degrees of inflammation. The data suggest that acemannan promotes dentin formation by stimulating primary human dental pulp cell proliferation, differentiation, extracellular matrix formation, and mineralization. Acemannan also has pulpal biocompatibility and promotes soft tissue organization.

Effect of calcium phosphate cements on growth and odontoblastic differentiation in human dental pulp cells

OBJECTIVE

Calcium phosphate cements (CPCs) are an interesting class of bone substitute materials. However, the biological effects of CPCs have not been well studied in human dental pulp cells (HDPCs). The purpose of this study was to investigate the effects of CPCs on the mechanical properties, growth, and odontoblastic differentiation in HDPCs compared with Portland cement (PC) and mineral trioxide aggregate (MTA).

METHODS

Experimental CPCs either containing chitosan (Ch-CPC) or without chitosan (CPC) were composed from the alpha-tricalcium phosphate powder. Setting time, compressive strength measurements, cell growth, alkaline phosphatase (ALP) activity, the levels of messenger RNA for differentiation-related genes, and mineralization of the HDPCs on various cements were assessed.

RESULTS

The setting time for CPC-Ch was 7.5 minutes, which was significantly less than the 8.6 minutes for the CPC. On the seventh day of immersion, the compressive strength of CPC-CH reached 13.1 MPa, which was higher than 10.8 MPa of CPC. CPC and Ch-CPC-treated cells showed decreased cell proliferation but increased the levels of ALP activity, enhanced mineralized nodule formation, and upregulated odontoblastic markers messenger RNA including osteonectin, osteopontin, bone sialoprotein, dentin matrix protein-1, matrix extracellular phosphoglycoprotein, and dentin sialophosphoprotein (DSPP), compared with untreated control. The response of CPC and CP-CPC were similar to that of PC and MTA. However, the adhesion, growth, and differentiation in Ch-CPC-treated cells were similar to that in the CPC.

CONCLUSION

CPC may be useful for pulp-capping applications based on its abilities to promote HDPC differentiation.

Toxicity of Flow Line, Durafill VS, and Dycal to dental pulp cells: effects of growth factors

INTRODUCTION

The objective was to determine the effects of growth factor treatment on dental pulp cell sensitivity to toxicity of 2 composite restoration materials, Flow Line and Durafill VS, and a calcium hydroxide pulp capping material, Dycal.

METHODS

Toxicity of the dental materials to cultures of primary dental pulp cells was determined by the MTT metabolism assay. The ability of 6 different growth factors to influence the toxicity was tested.

RESULTS

A 24-hour exposure to either Flow Line or Durafill VS caused approximately 40% cell death, whereas Dycal exposure caused approximately 80% cell death. The toxicity of Flow Line and Durafill VS was mediated by oxidative stress. Four of the growth factors tested (bone morphogenetic protein [BMP]-2, BMP-7, epidermal growth factor [EGF], and transforming growth factor [TGF]-beta) decreased the basal MTT values while making the cells resistant to Flow Line and Durafill VS toxicity except BMP-2, which made the cells more sensitive to Flow Line. Treatment with fibroblast growth factor-2 caused no change in basal MTT metabolism, prevented the toxicity of Durafill VS, but increased the toxicity of Flow Line. Treatment with insulin-like growth factor-I (IGF-I) increased basal MTT metabolism and made the cells resistant to Flow Line and Durafill VS toxicity. None of the growth factors made the cells resistant to Dycal toxicity.

CONCLUSIONS

The results indicated that growth factors can be used to alter the sensitivity of dental pulp cells to commonly used restoration materials. The growth factors BMP-7, EGF, TGF-beta, and IGF-I provided the best profile of effects, making the cells resistant to both Flow Line and Durafill VS toxicity.

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.

Reparative dentinogenesis induced by mineral trioxide aggregate: a review from the biological and physicochemical points of view

This paper aims to review the biological and physicochemical properties of mineral trioxide aggregate (MTA) with respect to its ability to induce reparative dentinogenesis, which involves complex cellular and molecular events leading to hard-tissue repair by newly differentiated odontoblast-like cells. Compared with that of calcium hydroxide-based materials, MTA is more efficient at inducing reparative dentinogenesis in vivo. The available literature suggests that the action of MTA is attributable to the natural wound healing process of exposed pulps, although MTA can stimulate hard-tissue-forming cells to induce matrix formation and mineralization in vitro. Physicochemical analyses have revealed that MTA not only acts as a "calcium hydroxide-releasing" material, but also interacts with phosphate-containing fluids to form apatite precipitates. MTA also shows better sealing ability and structural stability, but less potent antimicrobial activity compared with that of calcium hydroxide. The clinical outcome of direct pulp capping and pulpotomy with MTA appears quite favorable, although the number of controled prospective studies is still limited. Attempts are being conducted to improve the properties of MTA by the addition of setting accelerators and the development of new calcium silicate-based materials.

Effect of mineral trioxide aggregate on rat clonal dental pulp cells: expression of cyclooxygenase-2 mRNA and inflammation-related protein via nuclear factor kappa B signaling system

INTRODUCTION

Recently, mineral trioxide aggregate (MTA) has been routinely used for endodontic treatment. It is well-known that MTA induced secondary dentin formation in pulp cavity when it was applied to dentin, whereas its cytotoxicities were unclear. The purpose of this study was to evaluate the effect of MTA on rat clonal dental pulp cells, RPC-C2A.

METHODS

This study was conducted to observe the response of RPC-C2A cells on MTA with reverse-transcriptase polymerase chain reaction, Western blot analysis, and enzyme immunoassay. Data were compared by analysis of variance. Statistical significance was established at P <.01.

RESULTS

MTA significantly caused an up-regulation of cyclooxygenase-2 (COX-2) and inducible form of nitric oxide synthase (iNOS) mRNA expression. Furthermore, MTA caused inhibitory kappa B (IkappaB) phosphorylation and translocation of nuclear factor-kappa B (NF-kappaB) subunits to nucleus. Curucumin, an inhibitor of NF-kappaB activation, suppressed MTA-induced COX-2 and iNOS mRNA expressions. In addition, MTA increased the production of prostaglandin E(2) in comparison with the controls.

CONCLUSIONS

MTA induces inflammation via NF-kappaB signaling system.

Evaluation of pH and calcium ion release of new root-end filling materials

OBJECTIVE

The purpose of this study was to evaluate the pH and calcium ion release of 6 materials used for root-end filling and perforation repair.

STUDY DESIGN

Gray ProRoot MTA, gray MTA-Angelus, white MTA-Angelus, and CPM were compared to 2 experimental ones: MTA-exp, also based in Portland cement with a modified mixing liquid, and MBPc, an epoxy-resin based cement containing calcium hydroxide. After 3, 24, 72, and 168 hours the water in which each sample had been immersed was tested to determine the ph and calcium ion release.

RESULTS

All the analyzed materials showed alkaline pH and capacity to release calcium ions; however, a tendency of reduction of these characteristics was noted for all the analyzed materials, except for the MBPc, which showed a slight increase of pH among the 3 initial periods.

CONCLUSION

The results suggest that all materials investigated presented alkaline pH and ability of release of calcium ions.