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Now showing items 1 - 16 of 41

  • Development of Bis-GMA-free biopolymer to avoid estrogenicity

    Jun, Soo-Kyung   Cha, Jae-Ryung   Knowles, Jonathan C.   Kim, Hae-Won   Lee, Jung-Hwan   Lee, Hae-Hyoung  

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  • Carbon nanotube incorporation in PMMA to prevent microbial adhesion

    Kim, Kyoung-Im   Kim, Dong-Ae   Patel, Kapil D.   Shin, Ueon Sang   Kim, Hae-Won   Lee, Jung-Hwan   Lee, Hae-Hyoung  

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  • Investigation of the cytotoxicity of thermoplastic denture base resins.

    Lee, Jung-Hwan   Jun, Soo-Kyung   Kim, Si-Chul   Okubo, Chikahiro   Lee, Hae-Hyoung  

    PURPOSE: The purpose of this study was to investigate the in vitro cytotoxicity of thermoplastic denture base resins and to identify the possible adverse effects of these resins on oral keratinocytes in response to hot water/food intake.; MATERIALS AND METHODS: Six dental thermoplastic resin materials were evaluated: three polyamide materials (Smile tone, ST; Valplast, VP; and Luciton FRS, LF), two acrylic materials (Acrytone, AT; and Acryshot, AS), and one polypropylene resin material (Unigum, UG). One heat-polymerized acrylic resin (Vertex RS, RS) was chosen for comparison. After obtaining extracts from specimens of the denture resin materials (Phi=3D10 mm and d=3D2 mm) under different extraction conditions (37=E2=84=83 for 24 hours, 70=E2=84=83 for 24 hours, and 121=E2=84=83 for 1 hour), the extracts (50%) or serial dilutions (25%, 12.5%, and 6.25%) in distilled water were co-cultured for 24 hours with immortalized human oral keratinocytes (IHOKs) or mouse fibroblasts (L929s) for the cytotoxicity assay described in ISO 10993.; RESULTS: Greater than 70% viability was detected under all test conditions. Significantly lower IHOK and L929 viability was detected in the 50% extract from the VP (70=E2=84=83) and AT (121=E2=84=83) samples (P<.05), but only L929 showed reduced viability in the 50% and 25% extract from LF (37=E2=84=83) (P<.05).; CONCLUSION: Extracts obtained from six materials under different extraction conditions (37=E2=84=83, 70=E2=84=83, and 121=E2=84=83) did not exhibit severe cytotoxicity (less than 70% viability), although their potential risk to oral mucosa at high temperatures should not be ignored.=20
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  • Correlation in the mechanical properties of acrylic denture base resins

    LEE, Hae-Hyoung   LEE, Chung-Jae   ASAOKA, Kenzo  

    The aim of the present study was to measure various mechanical properties of acrylic denture base resins, including flexural modulus, flexural strength, fracture toughness, Barcol and Vickers hardness and their related properties, and to investigate correlations between different mechanical properties. Resin specimens were prepared according to manufacturers' recommended instructions. The mechanical properties were measured under specified standards. Data from the mechanical tests were examined using correlation tests. In general, the mean results for mechanical properties of each specimen group were differently ranked depending on the tested mechanical property. The flexural modulus value showed strong or reasonable positive correlation with those of proportional limit, flexural strength, and surface hardness. In contrast, fracture toughness revealed strong negative correlations with the flexural parameters and hardness values. Results of correlation tests for the different parameters can be used for estimation of mechanical performance of acrylic denture bases in clinical situation and for quality control purposes.
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  • Porosity of dental gypsum-bonded investments in setting and heating process

    Asaoka, Kenzo   Bae, Ji-Young   Lee, Hae-Hyoung  

    The porosity of gypsum-bonded investments for set and heated compacts was measured and theoretically computed quantitatively, because porosity is an effective factor for determining the strength, setting/heating expansion, and permeability of compacts at casting. A helium gas pycnometer was used to measure the solid volume of fine powders, powder-water mixtures, and porous compacts. The compositions of the conventional cristobalite investment and rapid-heating type investment were estimated from the measured solid densities of the as-received powders and the set investments. The porosity and water content of the set investments were determined from the experimental data. Excess water content in the set investment was calculated in relation to the elapsed time from the start of mixing with water. The experimental porosities of the set and heated investments were about 40% for dry set compacts and about 50% for fired compacts, which well agreed with the numerically computed estimations, respectively.
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  • Bone Cell Responses of Titanium Blasted with Bioactive Glass Particles

    Choi, Chang-Rak   Yu, Hye-Sun   Kim, Chul-Hwan   Lee, Jae-Hoon   Oh, Chung-Hun   Kim, Hae-Won   Lee, Hae-Hyoung  

    Surface modification of Ti-based metals is an important issue in improving the bone cell responses and bone-implant integration. Blasting Ti with granules (mostly alumina) is commonly used to prepare a clean surface and provide a level of roughness. In this study, glass granules with a bioactive composition were used as the blasting source to improve the surface bioactivity and biocompatibility of a Ti substrate. Bioactive glass particles with a composition of 70SiO(2)center dot 25CaO center dot 5P(2)O(5) were prepared using a sol-gel method. A Ti disc was blasted with glass particles using a dental blasting unit (BG-Ti). A Ti disc blasted with commercial spherical-shaped glass (G-Ti) and a disc without blasting (Ti) were also prepared for comparison. The blasted Ti contained a large number of glass particles after the blasting process. The surface roughness of the samples in ascending order was G-Ti>BG-Ti>Ti. Murine-derived preosteoblasts (MC3T3-E1) were seeded on the samples, and the cell growth, differentiation, and mineralization behaviors were observed. The osteoblastic cells attached well and spread actively over all the sample groups with extensive cytoskeletal processes. The level of cell growth on the BG-Ti showed a continual increase with culturing up to 7 days, showing good cell viability. However, there was no significant difference (ANOVA, p<0.05) with respect to the G-Ti and Ti groups. In particular, the alkaline phosphatase (AP) activity of the cells was significantly higher on the BG-Ti than on the other groups after culturing for 14 days. Moreover, the mineralization behavior of the cells, as assessed by Alizarin S Red, was superior on the BG-Ti to that observed on the other groups after culturing for 14 and 28 days. Overall, the blasting of Ti with a bioactive glass composition is considered beneficial for producing substrates with enhanced osteogenic potential.
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  • Porosity of dental phosphate-bonded investments after setting and heating processes

    Asaoka, Kenzo   Bae, Ji-Young   Lee, Hae-Hyoung  

    Porosities of set and burnout compacts of phosphate-bonded investments were determined. A gas pycnometer was used to measure the volumes, and hence the densities, of fine powders and porous compacts. Porosities of set and burnout compacts were then obtained from these data for as-received powders and dry set compacts by a numerical simulation method, subsequently leading on to the estimated compositions of conventional and rapid-heating investments used in this study. Excess water content in the hardening investment compact was evaluated as a function of setting time elapsed from the start of mixing. Porosities were about 24-32% for set compacts and 43% for burnout compacts, which well agreed with the numerically computed results. It was concluded that the functional composition of investment powder needed to achieve the optimal porosity as well as process parameters such as water-powder (W/P) ratio and keeping time of mixed investment casting slurry before heat treatment could be determined using the numerical simulation method developed in this study.
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  • Ceria-incorporated MTA for accelerating odontoblastic differentiation via ROS downregulation

    Jun, Soo-Kyung   Yoon, Ji-Young   Mahapatra, Chinmaya   Park, Jeong Hui   Kim, Hae-Won   Kim, Hyung-Ryong   Lee, Jung-Hwan   Lee, Hae-Hyoung  

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  • Evaluation of mold-enclosed shear bond strength between zirconia core and porcelain veneer.

    Song, Kwang-Hyun   Im, Yong-Woon   Lee, Jung-Hwan   Lee, Jonghyuk   Lee, Hae-Hyoung  

    This study aimed to evaluate the mold-enclosed shear bond strength (ME-SBS) of zirconia to veneering porcelain with different surface treatments. Colored or uncolored zirconia coupons were either highly polished or airborne-particle abraded. The specimens were divided into groups with/without application of liner. Veneering porcelain was fired into an alumina ring mold on the zirconia coupons. The assembled specimens were subjected to the ME-SBS test. The mean ME-SBS for groups ranged from 7-10 MPa with no significant difference (p>0.05). A three-way ANOVA showed that coloring and surface roughening of the zirconia specimen had no significant influence on the ME-SBS value, but liner application exhibited a significant effect with a minor decrease in the MESBS (p=3D0.049). Surface treatments (coloring, airborne-particle abrasion, and liner application) were found to not cause a significant increase to the zirconia-porcelain bond strength. The application of zirconia liner had a slight negative influence on the ME-SBS results.=20
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  • Role of nuclear mechanosensitivity in determining cellular responses to forces and biomaterials

    Lee, Jung-Hwan   Kim, Dong-Hwee   Lee, Hae-Hyoung   Kim, Hae-Won  

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  • Bone regeneration by bioactive hybrid membrane containing FGF2 within rat calvarium

    Hong, Ki Seok   Kim, Eun-Cheol   Bang, So-Hee   Chung, Chin-Hyung   Lee, Young Il   Hyun, Jung Keun   Lee, Hae-Hyoung   Jang, Jun-Hyeog   Kim, Tae-Il  

    This study examined the bone regeneration potential of a novel hybrid membrane consisting of collagen and nano-bioactive glass (nBG) incorporating basic fibroblast growth factor (FGF2) for use in guided bone regeneration. nBG was added to a reconstitution of collagen at a concentration of 30%, and the hybrid was formulated into a thin membrane. FGF2 (50 mu g/ml) was adsorbed to the hybrid membrane. This level of FGF2 was found to be the optimal concentration to stimulate osteoblastic differentiation in vitro. Three membrane groups, including pure collagen, collagen-nBG hybrid and its combination with FGF2 were implanted within a rat calvarium defect (phi = 5 mm) for a period of 3 weeks. Histomorphometric analysis was carried out to evaluate the bone regeneration within the defect. The results showed that the defect in the collagen-nBG-FGF2 membrane was recovered almost completely, while partial recovery was observed in the other membrane groups (collagen and collagen-BG). However, there was little defect recovery in the blank control. The new bone formation was as high as similar to 60, similar to 45, and similar to 30% of the defect treated with the collagen-nBG-FGF2, collagen-BG, and collagen, respectively, whilst only 4% of new bone was observed in the blank control. Overall, the nBG was shown to stimulate bone formation of the collagen membrane, and FGF2 synergistically accelerated the bone regeneration within a rat calvarium defect. (C) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 94A: 1187-1194, 2010.
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  • Evaluation of the flexural mechanical properties of various thermoplastic denture base polymers

    LEE, Hae-Hyoung   LEE, Jung-Hwan   YANG, Tae-Hyun   KIM, Yu-Jin   KIM, Si-Chul   KIM, Gyu-Ri   KIM, Hyung-Rae   LEE, Chung-Jae   OKUBO, Chikahiro  

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  • Performance of a glucose-reactive enzyme-based biofuel cell system for biomedical applications

    Jeon, Won-Yong   Lee, Jung-Hwan   Dashnyam, Khandmaa   Choi, Young-Bong   Kim, Tae-Hyun   Lee, Hae-Hyoung   Kim, Hae-Won   Kim, Hyug-Han  

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  • Evaluation of the flexural mechanical properties of various thermoplastic denture base polymers.

    Lee, Hae-Hyoung   Lee, Jung-Hwan   Yang, Tae-Hyun   Kim, Yu-Jin   Kim, Si-Chul   Kim, Gyu-Ri   Kim, Hyung-Rae   Lee, Chung-Jae   Okubo, Chikahiro  

    This study evaluated the flexural mechanical properties of various thermoplastic denture base polymers (six polyamides, four acrylic resins, polyester, polypropylene, and polycarbonate) by three different testing conditions; specimens were tested in water bath at 37=C2=B0C (Wet/Water, by ISO 20795-1), or in ambient air (Wet/Air) after being immersed in distilled water for 50 h, or after desiccation for 7 days (Dry/Air). The mean ultimate flexural strength (UFS) and flexural modulus (FM) for most products ranged from 27 to 61 MPa and from 611 to 1,783 MPa respectively, which failed to meet the minimum requirements of the international standard, except for polycarbonate (89 and 2,245 MPa). The mean UFS and FM values were ranked Dry/Air>Wet/Air>Wet/Water (p<0.05). In conclusion, the flexural mechanical properties of denture base polymers varied with the products and were significantly affected by the testing medium (air or water) and specimen conditions (wet or dry).=20
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  • Evaluation of Light-Activated Provisional Resin Materials for Periodontal Soft Tissue Management

    Jun, Soo-Kyung   Lee, Hae-Hyoung  

    The purpose of this study was to determine mechanical properties using a compressive test with cylinder specimen (h =3D 6 mm and phi =3D 4 mm) as well as cytotoxicity using elutes from disk specimen (phi =3D 10 mm and h =3D 2 mm) against human gingival fibroblasts and oral keratinocytes with light-activated provisional resin materials (Revotek LC and Luxatemp Solar) compared to chemically activated counterpart (Snap, Trim II, and Jet). Significantly increased compressive strength (210 similar to 280 MPa) was detected in light-activated products compared to chemically activated ones (20 similar to 65 MPa, P < 0.05) and similar compressive modulus was detected in both types (0.8 similar to 1.5 and 0.5 similar to 1.3 GPa). Simultaneously, the light-activated products showed less adverse effects on the periodontal soft tissue cells in any polymerization stage compared to the chemically activated products. Particularly, chemically activated products had significantly greater adverse effects during the "polymerizing" phase compared to those that were "already set" (P < 0.05), as shown in confocal microscopic images of live and dead cells. In conclusion, light-activated provisional resin materials have better mechanical properties as well as biocompatibility against two tested types of oral cells compared to the chemically activated counterpart, which are considered as more beneficial choice for periodontal soft tissue management.
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  • Multi-functional nano-adhesive releasing therapeutic ions for MMP-deactivation and remineralization.

    Jun, Soo-Kyung   Yang, Sun-A   Kim, You-Jin   El-Fiqi, Ahmed   Mandakhbayar, Nandin   Kim, Duck-Su   Roh, Jiyeon   Sauro, Salvatore   Kim, Hae-Won   Lee, Jung-Hwan   Lee, Hae-Hyoung  

    Restoration of hard tissue in conjunction with adhesive is a globally challenging issue in medicine and dentistry. Common clinical therapies involving application of adhesive and substitute material for functional or anatomical recovery are still suboptimal. Biomaterials with bioactivity and inhibitory effects of enzyme-mediated adhesive degradation can render a solution to this. Here, we designed a novel copper-doped bioactive glass nanoparticles (CuBGn) to offer multifunction: metalloproteinases (MMP) deactivation and remineralization and incorporated the CuBGn in resin-dentin adhesive systems, which showed most common failure of MMP mediated adhesive degradation among hard tissue adhesives, to evaluate proposed therapeutic effects. A sol-gel derived bioactive glass nanoparticles doping 10wt% of Cu (Cu-BGn) for releasing Cu ions, which were well-known MMP deactivator, were successfully created and included in light-curing dental adhesive (DA), a filler-free co-monomer resin blend, at different concentrations (up to 2wt%). These therapeutic adhesives (CuBGn-DA) showed enhanced (a)cellular bioactivity, cytocompatibility, microtensile bond strength and MMP deactivation-ability. In conclusion, the incorporation of Cu ions releasing nano-bioactive glass demonstrated multifunctional properties at the resin-dentin interface; MMP deactivation and remineralization, representing a suitable strategy to extend the longevity of adhesive-hard tissue (i.e. resin-dentin) interfaces.=20
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