Biomedical subjects

Shinn-Jyh Ding

Publications and source records attributed to Shinn-Jyh Ding.

11 recordsLinked to original sources

PubMed2007

Biocompatibility of various formula root filling materials for primary teeth.

The aim of this study was to compare the effects of different materials used in primary root canal fillings on the cell viability of human osteosarcoma cell lines. The experimental group contained six different types of root canal filling materials, including zinc oxide (ZnO) + eugenol + formocresol (FC), Ca(OH)(2) + FC, Ca(OH)(2) + Iodoform, Ca(OH)(2) + Iodoform + camphorated parachlorophenol (CPC), Ca(OH)(2) + CPC, and Vitapex. Cell viability tests were performed using tetrazolium bromide colorimetric (MTT) assay on human osteosacorma cell lines (U2OS). The results were analyzed using one-way analysis of variance (ANOVA) and Student-Newman-Keul's test with p < 0.05 showed statistical differences. The ZnO + eugenol + FC group and Ca(OH)(2) + FC group showed the lowest survival rates (p < 0.05). The Ca(OH)(2) + Iodoform + CPC group and Ca(OH)(2) + CPC group showed significantly lower survival rates at concentrations above 6 microL/mL (p < 0.05). The Ca(OH)(2) + Iodoform group and Vitapex group showed the highest survival rates (p < 0.05). We concluded that the use of calcium hydroxide with iodoform as a root filling base material is a better option than other medications.

Calcium Hydroxide↗

PubMed2006

Characterization of functionally graded hydroxyapatite/titanium composite coatings plasma-sprayed on Ti alloys.

Bioceramic coatings like hydroxyapatite (HA) have shown promising bioactive properties in load-bearing implant applications. The aim of this work is to deposit functionally graded HA/Ti layers consisting of an underlying Ti bond coat, the alternating layer, and an HA top-layer on Ti6Al4V substrates using plasma spray to improve the coating-substrate interface properties. The alternating layers were created by means of changing the feeding rate and input power of Ti and HA powders, which gradually decrease Ti content with increasing depth from the Ti bond-coat. The major consideration is to examine the stability of the graded coatings. Experimental results indicated that surface chemistry and morphology of the graded coatings were similar to those of monolithic HA coatings. The bond strength values of the as-sprayed graded coatings were much superior to those of monolithic HA coatings. The cyclic fatigue did have a statistically significant effect on bond strength of monolithic HA coatings, with a decrease of 23%. However, the graded coatings were able to survive 1 million cycles of loading in air without significantly reduced bond strength. The in vitro electrochemical measurement results also indicated that the graded coatings had a more beneficial and desired behavior than monolithic HA coatings after fatigue.

Alloys↗

PubMed2006

Comparison of frictional resistance after immersion of metal brackets and orthodontic wires in a fluoride-containing prophylactic agent.

INTRODUCTION: In this study, we investigated and compared the levels of frictional resistance between metal brackets and orthodontic wires after immersion in an acidified phosphate fluoride (APF) agent. METHODS: Three types of mandibular incisor stainless steel metal brackets with beta-titanium alloy wire (TMA), heat-activated nickel-titanium wire (Ni-Ti), and 2 sizes of stainless steel wires (SSW) were immersed in 0.2% APF and pH 6.75 artificial saliva solutions for 24 hours. The study included 480 bracket-wire specimens. The frictional resistance was measured on an EZ-test machine (Shimadazu, Tokyo, Japan) with a 5-N load cell. An Alastik (Quik-Stik Clear, A-1 Alastik, 3M Unitek, Monrovia, Calif) module ligated to the bracket was attached to the crosshead of the machine and pulled at a speed of 10 mm per minute for a distance of 5 mm. A completely randomized 1-way ANOVA was used to test for significant differences among the 3 bracket/wire specimens after immersion in 0.2% APF and pH 6.75 artificial saliva solutions. This was followed by the Student-Newman-Keuls multiple comparison of means ranking at P <.05 to determine differences between the groups. RESULTS: In the APF-immersed group, the static frictional force was greater than the kinetic frictional force. The frictional forces of the orthodontic wires had statistically significant differences (P <.05) in this progressive order: TMA, Ni-Ti, and SSW. Similar frictional force results were obtained in the pH 6.75 saliva group (P <.05). The frictional force values of the APF group were higher than those of the pH 6.75 saliva group (P <.05). CONCLUSIONS: This study demonstrates that the frictional forces of orthodontic brackets and wires are influenced by contact with fluoride-containing solutions.

Acidulated Phosphate Fluoride↗

PubMed2006

Effect of conditioners on bond durability of resin composite to Nd:YAP laser-irradiated dentin.

The aim of this study was to evaluate the effect of conditioners (sodium hypochlorite (NaOCl), Roth's ethylenediaminetetraacetic acid (EDTA), and phosphoric acid) on shear bond strength and morphology of Nd:YAP laser-irradiated dentin. In particular, the key focus was on the bond durability between resin composite and treated dentin after being subjected to thermocycling in artificial saliva between 5 degrees C and 55 degrees C. Results indicated that the application of phosphoric acid to laser-irradiated dentin produced a bond strength comparable to those using NaOCl and EDTA. Further, dentinal tubules which were closed after laser irradiation opened following the treatment with conditioners. When subjected to 3,000 thermocycles, the mean shear strength of the samples treated by the three conditioners following laser irradiation ranged from 9.7 to 12.6 MPa with a reduction of 25-33%--a reduction rate lower than that obtained using acid etching alone (50%). Among the three conditioners tested, only phosphoric acid treatment demonstrated an enhanced effect on bond durability of laser-irradiated dentin.

Acrylic Resins↗

PubMed2005

Induction of cyclooxygenase-2 expression in human pulp cells stimulated by dentin bonding agents.

OBJECTIVES: Histological investigations have demonstrated that dentin bonding agents can induce pulpal inflammation. However, there is little information on the precise mechanisms about dentin bonding agent-induced pulpal inflammation. Cyclooxygenase-2 (COX-2) is an inducible enzyme believed to be responsible for prostaglandin synthesis at the site of inflammation. The aim of this study was to investigate the effects of dentin bonding agents on the expression of COX-2 in human pulp cells. STUDY DESIGN: Human pulp cells were cultured from extracted impacted third molars using an explant technique. Patients gave informed consent. The reverse-transcriptase polymerase chain reaction and Western blot assays were used to investigate the effects of cultured human pulp cells exposed to dentin bonding agents. In addition, NS-398 (a selective COX-2 inhibitor) was added to test how it modulated the cytotoxic effects of dentin bonding agents. RESULTS: The exposure of quiescent human pulp cells to dentin bonding agents resulted in the induction of COX-2 mRNA and protein expression. The expression of COX-2 signals depended on the materials tested. In addition, NS-398 at noncytotoxic dose was not able to prevent dentin bonding agent-induced cytotoxicity (P > .05). CONCLUSION: The activation of COX-2 expression may be one of the pathogenesis of dentin bonding agent-induced pulpal inflammation. In addition, dentin bonding agent-induced cytotoxicity is not directly via the induction of COX-2 expression.

Acetone↗

PubMed2005

Mechanical properties of collagen gels derived from rats of different ages.

In a previous study, we found that different collagen gels produced using collagen fibrils extracted from 1-, 4- and 8-month-old rat tails essentially influenced the morphogenesis of epithelial cells. More importantly, the youngest collagen gel induces the highest level of cell apoptosis. The objective of this study was to investigate mechanical properties of various collagen gels correlated to the rat ages. A rheometer and dynamic mechanical analyzer were used to measure shear and compressive properties of hydrated collagen gels. Experimental results obtained from both testing modes showed that older age-related collagen gels possessed a larger elastic modulus, possibly due to the enhanced cross-linking degree. The moduli obtained in shear mode were 1.4-2.7-times greater than those in compression. The results of shear test and compressive test consistently indicated the age of rats did have a statistically significant effect on mechanical properties of hydrated collagen gels.

Aging↗

PubMed2004

Root canal sealers induce cytotoxicity and necrosis.

There are three types of the root canal sealers commonly used in clinical applications. They are calcium hydroxide base (Sealapex), zinc oxide-eugenol base (Canals), and epoxy-resin base (AH Plus). Elutable substances and degradation products from root canal sealers may gain access to periodontal tissue in a number of ways. The purpose of the present study was to evaluate the biologic effects of the root canal sealers on human oral cancer cell line (OC2). The tetrazolium bromide (MTT) assay was to evaluate the cell's survival rate. The DNA electrophoresis was used to evaluate the OC2 cell's DNA damage. The results demonstrated that the above root canal sealers' survival rates are in dose-dependent increase (p < 0.05). The toxicity of fresh mix group is higher than that of the mixed after 24h group. DNA fragmentation assay of sealer treated OC2 cells shows a smear layer pattern on the electrophoresis gel. There is no DNA damage found. The toxicity that regulated the cell death is not by the apoptic change of cells.

Apoptosis↗

PubMed2004

Metal ion release from new and recycled stainless steel brackets.

As orthodontic appliances can corrode with time in the oral environment, the aim of this study was to compare the release of metal ions from new and recycled brackets immersed in buffers of different pH values over a 48 week period. To simulate commercial recycling, the stainless steel brackets were divided into two groups: new and recycled. The bases of the latter were coated with adhesive and the brackets were heat treated before being immersed in the test solution for 48 weeks. The release of nickel, chromium, iron, copper, cobalt and manganese ions was analysed by atomic absorption spectrophotometry. Differences were compared using one-way analysis of variance. The results showed that recycled brackets released more ions than new brackets (P < 0.05). Brackets immersed in solutions of pH 4 released more ions than those immersed in solutions of pH 7, and the total amount of ions released increased with time over the 48 week period (P < 0.05). This study demonstrates that both new and recycled brackets will corrode in the oral environment. To avoid clinical side-effects, metal brackets should be made more resistant to corrosion, and recycled brackets should not be used.

Analysis of Variance↗

PubMed2003

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.

Aluminum Compounds↗

PubMed2003

Properties and immersion behavior of magnetron-sputtered multi-layered hydroxyapatite/titanium composite coatings.

A new biocompatible multi-layered coating was developed by alternately depositing Ti and HA layers on Ti6Al4V substrates using radio frequency magnetron-assisted sputter processing to improve the interface properties between the coating and the substrate. The multi-layered coating consisted of an underlying Ti bond coat, the alternating layer, and an HA top-layer. Between the bond coat and the top layer, an alternating layer was created by means of gradually increasing Ti content with increasing depth from the HA top-layer. The experimental results indicated that the as-sputtered coating had quite uniform thickness and well bonded to the substrate. The multi-layered coating exhibited a better electrochemical behavior than monolithic HA coating. The XRD and low vacuum SEM results consistently indicated that highly crystalline coating was not appreciably dissolvable in simulated body fluid. The adhesion strength higher than 60MPa did not change much even after 14 weeks of immersion. The multi-layered composite coatings had the advantages of high and non-declining adhesion strength and high resistance to SBF attack.

Biocompatible Materials↗

PubMed2002

The anticorrosion ability of titanium nitride (TiN) plating on an orthodontic metal bracket and its biocompatibility.

Typically, an orthodontic metal bracket is made from stainless steel. It has been shown that such metal may corrode in an acid- and chloride-rich environment. The purpose of the current study was to investigate a titanium nitride (TiN) ion-plated stainless steel orthodontic bracket's anticorrosion properties and compare its biocompatibility with that of non-TiN-plated brackets. The stainless-steel brackets studied here were tested in acidic artificial saliva. The plated metal bracket was produced by the titanium nitride (TiN) ion-plating method. The TiN-plating on the bracket surface was demonstrated to be successful by EDX analysis. The quantity of metallic-ion release under test immersion solutions was analyzed by atomic absorption spectrophotometry. Both TiN- and non-TiN-plated brackets may release detectable ions into the test solution, including nickel, chromium, manganese, copper, and iron (ferric). The anticorrosion ability of the plated bracket was analyzed by means of inductively coupled plasma atomic emission spectroscopy. The results revealed that the TiN-plated metal bracket did not increase the anticorrosion ability of the standard bracket. The biocompatibility of the TiN plating versus the standard bracket material resulting from bracket immersion in the test solution revealed no toxicity on U2OS cells using a methylthiazole tetrazolium (MTT) colorimetric assay. Clearly, the search for an improved technique for enhancing the anticorrosion ability of the normal metal orthodontic bracket should be continued.

Cell Line↗