Dental Materials Journal
Online ISSN : 1881-1361
Print ISSN : 0287-4547
ISSN-L : 0287-4547
Volume 29 , Issue 4
Showing 1-17 articles out of 17 articles from the selected issue
Original Papers
  • Yota TAKABAYASHI
    2010 Volume 29 Issue 4 Pages 353-361
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 13, 2010
    JOURNALS FREE ACCESS
    Six thermoplastic resins and conventional acrylic resin were examined to characterize their mechanical and physical properties, water sorption, solubility, flexural strength, modulus of elasticity, tensile strength and color stability. Thermoplastic resins for non-metal clasp dentures exhibiting low water sorption and solubility offer hygienic advantages. Since they have a low modulus of elasticity and are easily manipulated, these materials make it possible for larger undercuts to be used for retention compared to acrylic resin. Not all of the thermoplastic resins tested fractured after the bending test in contrast to the conventional denture base resin, which fractured when tested beyond its proportional limit. It was also found that clinically noticeable staining may occur on the polyamide resins and polyethylene terephtalate resins.
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  • Toshiyuki ITOTA, Toshiyuki NAKATSUKA, Kumiko TANAKA, Yoko TASHIRO, Joh ...
    2010 Volume 29 Issue 4 Pages 362-368
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 02, 2010
    JOURNALS FREE ACCESS
    The aim of this study was to evaluate the fluoride release, neutralizing ability and inhibitory effect on secondary caries of resin-based materials containing a silane-coated glass filler. Resin-based materials containing fluoro-boro-alumino-silicate glass coated by 3-methacryloxypropyltrimethoxysilane or 3-aminopropyltrimethoxysilane were used and resin material containing glass filler without coating was used as a control. The fluoride release and pH value after immersion were measured for 10 weeks. The inhibitory effect was also evaluated. During the initial period, the material with 3-aminopropyltrimethoxysilane gave the greater amount of fluoride release and produced a higher pH value compared with the other materials. However, the neutralizing ability of the material with 3-aminopropyltrimethoxysilane filler became weaker with ageing of the specimens. The mean depth of outer lesions was similar among the three materials. Within the limitations of this study, secondary caries around restorations could not be inhibited even for products showing high fluoride releasing and neutralizing ability.
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  • Yoshinori KUBOKI, Takamitu KOSHIKAWA, Hiroko TAKITA, Ryuichi FUJISAWA, ...
    2010 Volume 29 Issue 4 Pages 369-373
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 02, 2010
    JOURNALS FREE ACCESS
    Chromatography technology was employed to clarify the mechanism of interaction between multi-wall carbon nanotubes (MWCNT) and proteins. A column (16×100 mm) was packed with purified MWCNT, and various proteins were eluted with phosphate buffered saline (PBS) with and without gradient systems. It was found that albumin in bovine serum was eluted immediately from the column without any adsorption to MWCNT. Conversely, the non-albumin proteins, including a protein of 85 kDa molecular mass and a group of proteins with molecular masses higher than 115 kDa, exhibited considerably high affinity towards MWCNT. A sample of pure bovine serum albumin was also eluted immediately from the column, while lysozyme did not elute as a peak with PBS, but eluted with 0.6 M NaCl. Fundamentally, carbon nanotubes are devoid of any electrical charge. Therefore, other forces including the hydrogen bonds, hydrophilic interactions, and van der Waals forces were most probably responsible for the differential elution behaviors. In conclusion, this chromatographic method provided a simple and direct analysis of the interactions between carbon nanotubes and the various proteins.
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  • Guang HONG, Takeshi MAEDA, YingAi LI, Shinsuke SADAMORI, Taizo HAMADA, ...
    2010 Volume 29 Issue 4 Pages 374-380
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 02, 2010
    JOURNALS FREE ACCESS
    The purpose of this study was to determine the effect of PMMA polymer on dynamic viscoelasticity and plasticizer leachability of PEMA-based tissue conditioners. One PEMA polymer and one PMMA polymer were used in powder form with four formulations. The combination of 80 wt% ATBC, 15 wt% BPBG and 5 wt% ethyl alcohol was used as the liquid phase. The dynamic viscoelasticity and plasticizer leaching of each specimen were measured after 0, 1, 3, 7, and 14 days of immersion (37°C distilled water) using DMA and HPLC. A significant difference was found among the materials in the dynamic viscoelasticity and leaching of plasticizer. The materials containing 10 wt% PMMA showed the most stable dynamic viscoelasticity, and showed the lowest leaching of plasticizer. The results suggest that the addition of the PMMA polymer to the powder of a tissue conditioner can improve the durability of the PEMA-based tissue conditioner.
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  • Che-Shun WANG, Ker-Kong CHEN, Kiyoshi TAJIMA, Yuki NAGAMATSU, Hiroshi ...
    2010 Volume 29 Issue 4 Pages 381-391
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 23, 2010
    JOURNALS FREE ACCESS
    The effects of sandblasting media and steam cleaning treatment after sandblast were examined on tensile bond strength of porcelain to titanium. The use of the commercially available silica-coated alumina particles for sandblast was significantly effective for increasing bond strength than the conventional alumina. It might be due to the increased surface roughness and existence of remaining silica on titanium surface. Additional application of the steam cleaning on titanium surface after sandblasting could make the surface configuration clear in SEM by removing some sandblasted particles loosely embedded in titanium as well as the debris and oily contaminants. The resultant bond strength was significantly improved to reach almost the maximum strength of this porcelain-titanium system regardless of the kind of sandblasting media used, which was confirmed by the observation of the failure mode showing that most of the fracture surface was occupied by cohesive failure in porcelain.
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  • Yoshihiro FUJIMOTO, Mika IWASA, Ryosuke MURAYAMA, Masashi MIYAZAKI, Ak ...
    2010 Volume 29 Issue 4 Pages 392-397
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 02, 2010
    JOURNALS FREE ACCESS
    The purpose of this study was to analyze the ions released from a surface pre-reacted glass ionomer (S-PRG) filler in distilled water or lactic acid solution. S-PRG filler was mixed with either solution at 1000:1, 100:1, 10:1, and 1:1 ratios by weight. By means of inductively coupled plasma atomic emission spectroscopy and a fluoride electrode, elements released from S-PRG filler were identified to be Al, B, Na, Si, Sr, and F. To investigate the effect of solution pH on ion release, the pH values of the solutions before mixing and after 24 hours’ mixing with S-PRG were measured. After 24 hours’ mixing, the pH values of solutions at all ratios became more neutral or weakly alkaline regardless of their initial pH levels before mixing. In conclusion, results showed that S-PRG filler released several types of ions, and that ion release was influenced by the mixing ratio of the solution rather than the initial pH of the solution.
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  • Huaiqin ZHANG, Jianglin FANG, Zheng HU, Junchi MA, Yi HAN, Jie BIAN
    2010 Volume 29 Issue 4 Pages 398-402
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 02, 2010
    JOURNALS FREE ACCESS
    Mechanical roughening reportedly had a weakening effect on bond strength. Therefore, the purpose of this study was to evaluate the effect of an alternative surface roughening method, namely oxygen plasma treatment, on the tensile bond strength between denture base resin and soft liner. The soft liner used in this study was Soft Reverse, whilst the denture base material was Zi Ran. Three groups of specimens were prepared, comprising untreated specimens and oxygen plasma-treated specimens with exposure to air for 1 day and 2 days. All specimens were subjected to surface composition analysis and tensile bond strength testing. All data were analyzed using one-way ANOVA, and their mean values were compared using Tukey’s HSD test (p<0.01). Highest tensile bond strength was observed in the 1-day exposure group (5.2 MPa), whilst the lowest in the control group of untreated specimens (2.8 MPa). Hence, results of this study clearly indicated that oxygen plasma treatment was effective in enhancing tensile bond strength.
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  • Tatsuya MIYAZAKI, Satoshi MIYAUCHI, Akira TAWADA, Takahisa ANADA, Osam ...
    2010 Volume 29 Issue 4 Pages 403-410
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 02, 2010
    JOURNALS FREE ACCESS
    The present study was designed to investigate whether chondroitin sulfate (CS)-E, a CS structural isomer variant, alter the differentiation of macrophage cell line RAW264 cells to osteoclast-like cells. CS-B, CS-E, low molecular weight CS-E, synthetic chondroitin polysulfate (CPS) and heparin significantly inhibited the formation of tartrate-resistant acid phosphatase-positive multinuclear cells and pit formation on calcium phosphate (CaP)-coated plates. CS-E pre-coated on the CaP plate also inhibited pit formation. Digestion of CS on the cell surface by chondroitinase showed no effect on the osteoclastic differentiation of RAW264 cells whereas inhibitory effect on the differentiation of osteoblastic cell line MC3T3-E1. On the other hand, exogenously added fluorescein-labeled CS-E directory bound to fibronectin and RAW264 cells. These results suggest that CS-E structure on the surface of osteoblasts or bone matrix binds to cell adhesion molecule such as integrin on the pre-osteoclastic cells and inhibits the differentiation into osteoclasts. CS-E may have a potential in treating bone defect if combined with CaP materials.
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  • Chung-Jae LEE, Sung-Bem BOK, Ji-Young BAE, Hae-Hyoung LEE
    2010 Volume 29 Issue 4 Pages 411-417
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 28, 2010
    JOURNALS FREE ACCESS
    This study examined the adaptation accuracy of acrylic denture base processed using fluid-resin (PERform), injection-moldings (SR-Ivocap, Success, Mak Press), and two compression-molding techniques. The adaptation accuracy was measured primarily by the posterior border gaps at the mid-palatal area using a microscope and subsequently by weighing of the weight of the impression material between the denture base and master cast using hand-mixed and automixed silicone. The correlation between the data measured using these two test methods was examined. The PERform and Mak Press produced significantly smaller maximum palatal gap dimensions than the other groups (p<0.05). Mak Press also showed a significantly smaller weight of automixed silicone material than the other groups (p<0.05), while SR-Ivocap and Success showed similar adaptation accuracy to the compression-molding denture. The correlationship between the magnitude of the posterior border gap and the weight of the silicone impression materials was affected by either the material or mixing variables.
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  • Mustafa ZORTUK, Kerem KILIC, Aysegul Guleryuz GURBULAK, Bulent KESIM, ...
    2010 Volume 29 Issue 4 Pages 418-424
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 17, 2010
    JOURNALS FREE ACCESS
    The effects of desensitizer, disinfectant, saliva, blood, and hydrogen peroxide on the tensile bond strength between adhesive and ceramic as well as between adhesive and dentin were examined. Sixty 7×3 mm pressed ceramic discs of IPS e.max were fabricated and randomly assigned to six groups of different dentin surface treatments (control, desensitizer, disinfectant, saliva, blood, and hydrogen peroxide). Representative samples of fractured specimens were observed by SEM (scanning electron microscopy). There were significant differences between the control group and saliva, blood, and hydrogen peroxide groups (p<0.05). However, there were no significant differences between any other dentin surface treatment groups (p>0.05). Results of this study suggested that only saliva, blood, and hydrogen peroxide influenced the tensile bond strength between dentin and ceramic.
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  • Jie LIN, Akikazu SHINYA, Harunori GOMI, Akiyoshi SHINYA
    2010 Volume 29 Issue 4 Pages 425-432
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 23, 2010
    JOURNALS FREE ACCESS
    This study evaluated the shear bond strengths and etching patterns of seven self-adhesive resin cements to human enamel specimens which were subjected to one of the following surface treatments: (1) Polishing with #600 polishing paper; (2) Phosphoric acid; (3) G-Bond one-step adhesive; or (4) Phosphoric acid and G-Bond. After surface treatment, the human incisor specimens were bonded to a resin composite using a self-adhesive resin cement [Maxcem (MA), RelyX Unicem (UN), Breeze (BR), BisCem (BI), seT (SE), Clearfil SA Luting (CL)] or a conventional resin cement [ResiCem (RE)]. Representative morphology formed with self-adhesive resin cements showed areas of etched enamel intermingled with areas of featureless enamel. In conclusion, etching efficacy influenced the bonding effectiveness of self-adhesive resin cements to unground enamel, and that a combined use of phosphoric acid and G-Bond for pretreatment of human enamel surfaces improved the bond strength of self-adhesive resin cements.
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  • Li-Hong He, Ludwig Jansen van Vuuren, Nina Planitz, Michael V. Swain
    2010 Volume 29 Issue 4 Pages 433-437
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 17, 2010
    JOURNALS FREE ACCESS
    The purpose of this study was to investigate the properties of a die hardener penetrated layer and evaluate its protective effects on the surface of die stone. A commercial die hardener (PDQ die hardener, Whipmix corp., USA) was tested on a die stone (GC Fujirock® EP die stone, GC Europe, Belgium) and a dental plaster (Dental Stone, United States Gypsum Company, USA). Nanoindentation and micro-scratch tests were performed on both coated and uncoated specimens. The scratch damage was observed by SEM and the penetration depth of die hardener was detected by the affiliated EDX. Upon drying, the die hardener penetrated into the die stone to a depth of 3-5 μm, and deposited a thin film on the surface of die stone. Although the die hardener penetrated layer did not show improved mechanical properties, the die hardener film on the surface did protect the specimens from abrasion damage.
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  • Isao HIRATA, Mai AKAMATSU, Eri FUJII, Suchit POOLTHONG, Masayuki OKAZA ...
    2010 Volume 29 Issue 4 Pages 438-445
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 17, 2010
    JOURNALS FREE ACCESS
    Hydroxyapatite formation was examined at the surface of self-assembled monolayers (SAMs) modified with four functional groups, -COOH, -NH2, -CH3, and -OH. For COOH-SAM and NH2-SAM, scanning electron spectroscopic observation showed that flake-like sheet crystals covered the whole wafer and small broccoli-like crystals were observed occasionally on the flake-like crystal base layer. For CH3-SAM and OH-SAM, no flake-like sheet crystals were observed; broccoli-like crystals were observed in a dispersed manner for CH3-SAM, but in localized spots for OH-SAM. X-ray diffraction patterns showed a strong apatite pattern oriented toward the c-axis direction for COOH-SAM. ESCA analysis revealed distinct Ca, P, O peaks for COOH-, NH2-, CH3-, and OH-SAM. Surface plasmon resonance (SPR) analysis indicated that during the supply of supersaturated calcium phosphate solution, the deposition of precipitates increased monotonically with time for COOH-SAM, increased slightly for NH2-SAM, but little increase in deposition was detected for CH3-SAM and OH-SAM.
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  • Hiroshi MURATA, Hironori CHIMORI, Guang HONG, Taizo HAMADA, Hiroki NIK ...
    2010 Volume 29 Issue 4 Pages 446-453
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 16, 2010
    JOURNALS FREE ACCESS
    Chemical cleansing by denture cleansers is the first choice for denture plaque control of tissue conditioners. This study evaluated the influences of denture cleansers on the surface quality of tissue conditioners by determining surface roughness and porosity. Three tissue conditioners (Hydro-Cast, SR-Ivoseal, Visco-Gel) and 3 types of denture cleansers (Pika [enzyme type], Polident [neutral peroxide type with enzymes], Steradent [alkaline peroxide type]) were evaluated. Five specimens of each tissue conditioner/solution combination for each time period of immersion were prepared. The surface roughness of dental stone casts made from the tissue conditioners was evaluated using a profilometer. The surface quality of Hydro-Cast and Visco-Gel tended to be most deteriorated by the alkaline peroxide cleanser. The enzyme type of denture cleansers is most suitable for tissue conditioners in terms of surface quality. The suitable period for application of the enzyme cleansers would range from 3 to 7 days.
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  • Wallapat SANTAWISUK, Widchaya KANCHANAVASITA, Chakrit SIRISINHA, Cholt ...
    2010 Volume 29 Issue 4 Pages 454-460
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 16, 2010
    JOURNALS FREE ACCESS
    The purpose of this study was to evaluate the dynamic viscoelastic properties of experimental silicone soft lining materials, Silastic® MDX 4-4210 reinforced with silica fillers. Storage modulus (E’), loss modulus (E”) and damping factor (tan δ) were determined using a dynamic mechanical analyzer under a deformation strain level of 0.27% at test frequency and a temperature range of 1 Hz and 0 to 60°C, respectively. The degree of silica dispersion was also studied using a field emission scanning electron microscopy (FE-SEM). One-way ANOVA and Tukey’s HSD test results indicated that the prepared silicone elastomers provided a significantly greater damping factor, but less storage modulus than GC Reline Soft and Tokuyama Sofreliner Tough (p<0.001). The storage moduli, loss moduli and damping factor of the experimental silicone elastomers increased with increasing amounts of fumed silica. In conclusion, the experimental silicone elastomers revealed acceptable dynamic viscoelastic properties to be used as denture soft lining materials.
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  • Setsuo SAITOH, Kaori SASAKI, Takashi NEZU, Masayuki TAIRA
    2010 Volume 29 Issue 4 Pages 461-468
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 23, 2010
    JOURNALS FREE ACCESS
    Three commercially available tissue conditioners —Tissue conditioner II (STII), Tissue conditioner (GTC), and Tissue Care (TTC)— were tested using a rheometer to evaluate their viscoelasticity under compression at a constant distortion (10%). Immediately after fabrication, STII showed the highest hardness and compressive modulus of elasticity, followed by TTC and GTC. TTC showed the highest relaxation rate, followed by GTC and STII. STII and GTC showed equivalent relaxation times, while TTC showed the shortest relaxation time. The modulus of viscosity was highest in STII, followed by GTC and TTC. The immersion of each sample in water resulted in increases in hardness, compressive modulus of elasticity, relaxation time, and modulus of viscosity and decreases in relaxation rates. The three products have different viscoelastic properties. Further, the results indicate that STII and GTC exhibit better performance when used as functional impression materials, while TTC exhibits better performance when used as a tissue conditioner.
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  • Florian Just WEGEHAUPT, Jasmin BETSCHART, Thomas ATTIN
    2010 Volume 29 Issue 4 Pages 469-474
    Published: 2010
    Released: August 07, 2010
    [Advance publication] Released: July 23, 2010
    JOURNALS FREE ACCESS
    This study aimed to determine the influence of sodium hypochlorite (NaOCl) contamination on the microhardness of build-up composites. Fifty-two samples, from each of three build-up materials (LuxaCore Dual, MultiCore flow and Rebilda DC) were prepared. Half of the samples from each material were stored in physiologic saline (baseline control) while the other halves were stored in NaOCl. After 1 h, the samples were rinsed with tap water, cut axially and measured for Knoop hardness at different depth levels. The results were analysed by ANOVA and unpaired t-tests (p<0.05). Significant differences in microhardness were observed for LuxaCore Dual up to 0.2 mm, Rebilda DC up to 0.3 mm, and for MultiCore flow up to 0.4 mm under the surface level. Contact with sodium hypochlorite on build-up materials causes reduction of the microhardness. The softening is not only limited on the surface, but can also be found in deeper layers of build-up materials.
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