Tsui-Hsien Huang

The Effect of Setting Accelerator on Properties of Mineral Trioxide Aggregate

The purpose of this study was to investigate the effect of a sodium phosphate dibasic (Na2HPO4) setting accelerator on the properties of white-colored mineral trioxide aggregate (WMTA). Setting times were measured by using a Gilmore needle. Changes in the pH value, diametral tensile strength, and phase composition of WMTA were evaluated. By using a 15% Na2HPO4 solution as a liquid phase mixed with WMTA, the setting time was significantly reduced to 26 minutes rather than the usual 3 hours. The 15% Na2HPO4 promoted WMTA to achieve a maximum diametral tensile strength of 4.9 MPa at an initial 6-hour aging time and 1 MPa for the cement mixed with water. The pH value of the 15% Na2HPO4-mixed cement was changed from an initial 11.0 to a high of 13.2, which was similar to the results using water. The results suggest that the Na2HPO4 solution may be an effective setting accelerator for WMTA.

Comparison of Calcium and Silicate Cement and Mineral Trioxide Aggregate Biologic Effects and Bone Markers Expression in MG63 Cells

Bone cell (MG63) biocompatibility and bone marker expression were compared after calcium and silicate base cement (CS) and mineral trioxide aggregate (MTA) treatment. X-ray diffraction was used to identify material surface structure, and tetrazolium bromide colorimetric assay was used to evaluate the cell viability. The relative mitogen activation protein kinase expression was compared with Western blot, and bone marker expression was evaluated with reverse transcriptase polymerization chain reaction. The results showed that CS and MTA are similar chemical structures and biocompatible with MG63 cells. CS and MTA cements showed good MG63 cell proliferation by high phosphor extracellular signal-regulated kinase expression levels. CS and MTA cements showed the evident type I collagen, osteocalcin, alkaline phosphatase, bone sialoprotein, and osteopontin expression. Both MTA and CS cements are biocompatible and appear to have osetoconduction effects on bone cells.

The Effect of a Physiologic Solution pH on Properties of White Mineral Trioxide Aggregate

The purpose of this study was to investigate the effect of two solutions differing by pH (6.4 and 4.0) and the use of a setting accelerator (15% Na(2)HPO(4) solution) on the properties of white-colored mineral trioxide aggregate (WMTA). These studies indicated that pH 4.0 had a deleterious effect on the morphology of WMTA mixed with water, however, not for WMTA mixed with Na(2)HPO(4). When immersed in a pH 4.0 solution for 7 days, WMTA mixed with water or Na(2)HPO(4) achieved a diametral tensile strength of 7.9 and 9.0 MPa, respectively, which was significantly lower (p < 0.05) than those obtained at pH 6.4 (11.2 and 12.0 MPa) but significantly higher (p < 0.05) than day 0 samples (4.4 and 4.8 MPa). Mixing WMTA with the accelerator did not significantly affect the microstructure, solubility, or strength in an acidic environment.

Effects of mineral trioxide aggregate (MTA) extracts on mitogen-activated protein kinase activity in human osteosarcoma cell line (U2OS)

Extracellular regulated kinases (ERKs)-1 and -2 are members of the MAPK family of protein kinases involved in the proliferation, differentiation and apoptosis of bone cells. The purpose of the present study investigated the biocompatibility role, and signaling pathways of components of mineral trioxide aggregate (MTA) by culturing human osteosarcoma cell line (U2OS) in the presence of materials. Biocompatibility effects were assessed using the MTT assay for mitochondrial enzyme activity. The statistical analysis of the survival rate was performed using one-way analysis of variance (ANOVA) with p<0.05 shown statistical difference. The signaling pathway of MTA-treated U2OS cells were assessed by the western blotting methods. Dose-dependent and time-dependent tests were conducted. The results showed that the survival rates of the MTA extract experimental groups were higher than that of the control group (p<0.05). ERKs activity was dose-dependent, decreasing as the concentrations of the MTA extract decreased, and was time-dependent, decreasing as the treatment time increased. Suppression of ERK pathway by PD98059 resulted in dose-dependent and time-dependent decreases. The findings suggest that MTA is a biocompatible material to U2OS cells, and the ERK kinase pathway plays a signal transduction role in the MTA treated U2OS cells.

The biocompatibility evaluation of epoxy resin-based root canal sealers in vitro

The cytotoxic and mutagenic effects of epoxy resin-based root canal sealer AH26 and AH-Plus were determined in vitro. Root canal sealers were eluted for 24 h in dimethyl sulfoxide (DMSO) and diluted in culture medium. Cytotoxic effects were assessed using the MTT [tetrazolium dye, 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide, C18H16N5SBr] assay for mitochondrial enzyme activity and also the cell viability. Genotoxicity assays were assessed using the alkaline single cell gel electrophoresis assay (comet assay) for DNA damage measurement. Result indicated that both the AH26 and AH-Plus sealers exhibited a dose-dependent increase in astrocyte toxic effects. Additionally, dose-dependent astrocyte DNA damage was also noted for both sealers. Therefore, these epoxy resin-based sealers, AH26 and AH-Plus demonstrated both cytotoxicity and genotoxicity in vitro.

Properties of an Accelerated Mineral Trioxide Aggregate–like Root-end Filling Material

The purpose of the study was to examine the physicochemical properties of mineral trioxide aggregate (MTA)-like cements prepared from SiO(2), CaO, and Al(2)O(3) as matrices, and ZnO, MgO, and Fe(2)O(3) as additives. The MTA-like cements showed a significantly (p < 0.05) faster setting time (<14 minutes) than MTA when mixed with water, although there was a significant decrease (p < 0.05) in diametral tensile strength, ranging from 0.9 to 3.1 MPa in comparison to MTA (4.4 MPa). The addition of ZnO, MgO, and Fe(2)O(3) to the MTA-like cement led to a significantly (p < 0.05) higher strength than MTA-like cement without additives. The pH values of the MTA-like cements were changed from an initial 11 to a high of 13, similar to the results of MTA. Future characterization of the examined MTA-like cement with shortened setting time is needed before it is considered a viable candidate for dental root-end-filling applications.

Immersion behavior of plasma-sprayed modified hydroxyapatite coatings after heat treatment

Abstract The effect of heat treatment was studied on plasma-sprayed hydroxyapatite (HA) coatings modified by addition of SiO 2 , CaO, P 2 O 5 and Na 2 O. Morphological and chemical changes of these heat-treated coatings underwent in simulated body fluid (SBF) were also investigated. The results showed that during plasma spraying, P 2 O 5 and SiO 2 enhanced the thermal decomposition of the HA structure, while CaO and Na 2 O did not. Annealing of the coatings in air at 650 °C led to recrystallization of amorphous calcium phosphate and effectively increased the conversion of non-apatite phase (TCP) into apatite. The heat treatment also resulted in a reduction of ‘flake-type’ structures associated with plasma-sprayed coatings. When immersed in SBF, the SiO 2 - and CaO-containing HA coatings did not show apatite precipitation in contrast to three other types of samples. That because of their TCP content showed the formation of apatite spherulites after 30-day immersion in SBF.

Evaluation of the genotoxicity of zinc oxide eugenol-based, calcium hydroxide-based, and epoxy resin-based root canal sealers by comet assay.

Three main types of root canal sealer are currently commonly used in pulp treatment: zinc oxide eugenol-based, calcium hydroxide-based, and epoxy resin-based sealers. In the present study, the genotoxicity of sealer on oral carcinoma cells was evaluated by single-cell gel electrophoresis assay (comet assay). The whole length of the comet and the diameter of the head were measured using an image analysis system. The results were analyzed by one-way analysis of variance to compare the various means. The zinc oxide eugenol-based sealers (Canals, Canals-N, and Tubilseal) did not always cause a dose-dependent increase in genotoxicity. The resin-based sealers (Topseal, AH 26, and AH Plus) caused a dose-dependent increase in genotoxicity, but no such effect was seen with the calcium hydroxide-based sealer (Sealapex). The highest level of DNA damage was induced by the resin-based sealers.

Cytotoxicity of Orthodontic Wire Corroded in Fluoride Solution In Vitro

OBJECTIVE To investigate the toxicity of fluoride corrosion extracts of stainless steel (SS) and nickel-titanium (NiTi) wires on a human osteosarcoma cell line (U2OS). MATERIALS AND METHODS The SS and NiTi wires were corroded by an electrochemical method with the application of three kinds of electrolytes: 0.2% pH 3.5 acidulated phosphate fluoride (NaF) in artificial saliva, and pH 4 and pH 6.75 artificial saliva solutions. The extracts were analyzed for nickel, chromium, and titanium ions by the atomic absorption method. The extracts were diluted with medium to different concentrations (1, 0.1, and 0.01 microL/mL). The cell survival rate was determined by the ability of test cells to cleave the tetrazolium salt to form a formazan dye. RESULTS The results were compared using one-way analysis of variance. Differences between the treatment means were analyzed using a Student-Newman-Keuls (SNK) test and were considered significant at P < .05. The release of ionic nickel was different in different extract groups (P < .05). The SS and NiTi wires in the 0.2% pH 3.5 NaF artificial saliva group caused a dose-dependent decrease in the survival rate (P < .05). Survival rates of cells in the groups exposed to extracts of SS and NiTi wires in pH 4 and pH 6.75 artificial saliva solutions showed no statistical differences (P >.05). CONCLUSIONS Orthodontic wires in acidulated fluoride saliva solution can cause U2OS cell toxicity.

The synergistic effects of fibroblast growth factor-2 and mineral trioxide aggregate on an osteogenic accelerator in vitro.

AIM To examine the effects of mineral trioxide aggregate (MTA)/fibroblast growth factor-2 (FGF-2) on material properties and in vitro human dental pulp cell (hDPCs) behaviour. METHODOLOGY The setting time and diametral tensile strength (DTS) of MTA and MTA/FGF-2 were measured. The structure of specimens before and after soaking in DMEM was examined under a scanning electron microscope. Alamar Blue was used for evaluating hDPCs proliferation. An enzyme-linked immunosorbent assay was employed to determine ALP and osteocalcin (OC) expression in hDPCs cultured on cements. The effect of small interfering RNA (siRNA) transfection targeting fibroblast growth factor receptor (FGFR) was also evaluated. One-way analysis of variance was used to evaluate the significance of the differences between the mean values. RESULTS Setting time and DTS data were not found to be significant (P > 0.05) between MTA with and without FGF-2. Cell proliferation and differentiation increased significantly (P < 0.05) with FGF-2 mixed MTA. After siRNA transfection with FGFR, the proliferation and differentiation behaviour of the hDPCs appreciably decreased when cultured on an MTA/FGF-2 composite. In contrast, no significant amounts (P > 0.05) of ALP and OC were secreted by hDPCs seeded on MTA. CONCLUSIONS Mineral trioxide aggregate with FGF-2 content enhanced the higher expression of hDPCs proliferation and osteogenic differentiation as compared to pure MTA cement.