A new resin-bonded retrograde filling material
This study determined the physical properties and cytotoxicity of a novel root-end filling material (NRC).
NRC is a powder and liquid system. The liquid is composed of hydroxyethylmethacrylate, benzoyl peroxide, toluidine, and toluenesulfinate. And the powder is made of calcium oxide, calcium silicate, and triphenylbismuth carbonate. The setting time, compressive strength, and pH change of NRC and gray and white mineral trioxide aggregate (MTA) were determined according to ISO standardization. MC3T3-E1 cells were cultured on NRC and white MTA for determining MTT scores. The absorbance of formazan was measured at 570 nm with a spectrophotometer. The MTT assay was performed in triplicate and repeated in 2 cultures. One-way analysis of variance was used to determine statistical differences in physical properties and MTT assay (P < .05).
Mean setting time of materials tested were: NRC 12.5 +/- 0.3 minutes, gray MTA 345.5 +/- 96.2 minutes, and white MTA 318.0 +/- 56.0 minutes. After 24 hours, the mean compressive strengths were: NRC, 21.6 +/- 5.5 MPa, gray MTA: 7.7 +/- 3.3 MPa, and white MTA, 18.9 +/- 3.2 MPa. The pH of the test materials were: NRC 12.0, gray MTA 12.2, and white MTA 11.9. There were no statistically significant differences in compressive strength and pH between white MTA and NRC. The compressive strength of gray MTA was significantly lower than white MTA and NRC (P < .05). The setting time of NRC was significantly lower than white and gray MTA. In MTT assay, both NRC and white MTA were not cytotoxic to MC3T3-E1 cells.
It was concluded that the setting time, compressive strength, pH, and initial biocompatibility results of NRC are favorable for a root-end filling material.
Available from: PubMed Central
- "It contains bioactive powders such as calcium oxide and calcium silicate, triphenylbismuth carbonate as opacifier. Organic resin matrix of this cement is composed of 2-hydroxyethylmethacrylate (HEMA) as a resin monomer, benzoyl peroxide as an initiator, toluidine and toluenesulfinate as catalyst and accelerator.7 The probable polymerization reaction of NRC is shown at Figure 1. "
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ABSTRACT: New resin cement (NRC) has been developed as a root repairing material and the material is composed of organic resin matrix and inorganic powders. The aim of this study was to compare the rat subcutaneous tissue response to NRC and mineral trioxide aggregate (MTA) cement and to investigate the tissue toxicity of both materials.
Sixty rats received two polyethylene tube-implants in dorsal subcutaneous regions, MTA and NRC specimens. Twenty rats were sacrificed respectively at 1, 4 and 8 wk after implantation and sectioned to 5 µm thickness and stained with Hematoxylin-Eosin (H-E) or von-Kossa staining. The condition of tissue adjacent to the implanted materials and the extent of inflammation to each implant were evaluated by two examiners who were unaware of the type of implanted materials in the tissues. Data were statistically analyzed with paired t-test (p < 0.05).
In specimens implanted with both NRC and MTA, severe inflammatory reactions were present at one wk, which decreased with time. At eighth wk, MTA implanted tissue showed mild inflammatory reaction, while there were moderate inflammatory reactions in NRC implanted tissue, respectively. In NRC group, von-Kossa staining showed more calcification materials than MTA group at eighth wk.
It was concluded that the calcium reservoir capability of NRC may contribute to mineralization of the tissues.
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ABSTRACT: Modular visualization environments (MVEs) have recently been regarded as the de facto standard for scientific data visualization, mainly due to adoption of the visual programming style, reusability, and extendability. However, since scientists and engineers as the MVE principal user are not always familiar with how to map numerical data to proper graphical primitives, the set of built-in modules is not fully used to construct necessary application networks. Therefore, a certain mechanism needs to be incorporated into MVEs, which makes use of heuristics and expertise of visualization specialists (visineers), and which supports the user in designing his/her applications with MVEs. The Wehrend's goal-oriented taxonomy of visualization techniques is adopted as the basic philosophy to develop a system, called GADGET, for application design guidance for MVEs. The GADGET system interactively helps the user design appropriate applications according to the specific visualization goals, temporal efficiency versus accuracy requirements, and such properties as dimension and mesh type of a given target dataset. Also the GADGET system is capable of assisting the user in customizing a prototype modular network for his/her desired applications by showing execution examples involving datasets of the same type. The paper provides an overview of the GADGET guidance mechanism and system architecture, with an emphasis on its knowledge base design. Sample data visualization problems are used to demonstrate the usefulness of the GADGET system.
Available from: Zhenglin Yuan
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ABSTRACT: This study investigated the cytotoxicity of bioaggregate (BA) and the effect of BA on mineral associated gene expression in osteoblast cells.
The cytotoxicity of BA to mouse MC3T3-E1 osteoblast cells was evaluated via the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay after 1, 2, and 3 days of culture. The expression of mineral associated genes (collagen type 1, osteocalcin, and osteopontin) was assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and compared expression after exposure to BA or mineral trioxide aggregate (MTA). The data were analyzed by one-way analysis of variance and the Tukey test.
BA was essentially nontoxic to osteoblast cells. The expression of collagen type 1, osteocalcin, and osteopontin genes significantly increased in the BA group compared with that in the MTA group on the second or third day of culture.
BA appears to be a novel nontoxic root-end filling biomaterial and be able to induce mineralization-associated gene expression in osteoblast cells.
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