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Boonlert KUKIATTRAKOON, Chanothai HENGTRAKOOL, Ureporn KEDJARUNE-LEGGA ...
2010 年 29 巻 5 号 p.
502-511
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/04
ジャーナル
フリー
This study was conducted to evaluate the titratable acidity and effect of naturally acidic agents on the surface microhardness, elemental composition, and surface morphology of fluorapatite-leucite ceramics. One hundred and ten ceramic disks (IPS d.SIGN), 12.0 mm in diameter and 2.0 mm in thickness, were fabricated. Before immersion, the baseline data of Vickers microhardness and elemental composition were recorded. Four groups were immersed in acidic agents (citrate buffer solution, green mango juice, and pineapple juice) and deionized water (control) at 37ºC for 168 hours, whereas one group was immersed in 4% acetic acid at 80ºC for 168 hours. After immersion, specimens were evaluated and data were analyzed using one-way repeated ANOVA and Tukey’s test (α=0.05). Microhardness values significantly decreased after immersion (
p<0.05). In terms of elemental composition, the weight percentages of silicon, potassium, aluminum, and sodium also decreased after immersion (
p<0.05). Results of this study showed that fluorapatite-leucite ceramics were affected by long-term immersion in acidic agents.
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Linlin HAN, Takashi OKIJI, Seigo OKAWA
2010 年 29 巻 5 号 p.
512-517
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/01
ジャーナル
フリー
The purpose of this study was to analyze the ultrastructures and chemical compositions of precipitates formed on mineral trioxide aggregate (MTA; White ProRoot MTA) immersed in distilled water (DW) or phosphate buffered saline (PBS), based on the attribution that MTA’s bioactivity and sealing ability are influenced by its interaction with the external fluid environment. After 1 and 14 days of immersion, precipitates formed on MTA disks were analyzed using wavelength-dispersive X-ray spectroscopy electron probe microanalyzer with image observation function (SEM-EPMA; EPMA1601, Shimadzu, Kyoto, Japan), and Fourier transform-infrared (FT-IR) spectroscopy. On DW specimens, cubic-like crystals containing Ca, O, and C (17, 66, and 17 at% respectively) were produced. State analysis of calcium k
β spectrum also revealed calcium hydroxide. On PBS specimens, acicular-spherical and lath-like crystals with Ca/P molar ratios of 1.42 and 1.58 respectively were produced. In conclusion, the precipitates formed on DW specimens were identified as calcium carbonate and calcium hydroxide primarily, whereas the precipitates on PBS specimens were inferred to be amorphous calcium phosphate.
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Ye ZHANG, Hiroyasu KANETAKA, Yuya SANO, Mitsuhiro KANO, Tada-aki KUDO, ...
2010 年 29 巻 5 号 p.
518-528
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/04
ジャーナル
フリー
The aim of this study was to analyze the effects of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer on fibrous tissue formation and cell adhesion plaque (CAP)-forming reactions. Silastic elastomer (SE) plates coated (experimental group) and uncoated (control group) with MPC polymer were prepared for
in vivo and
in vitro experiments. For the
in vivo animal experiments, SE plates were implanted subcutaneously in the rat dorsal region. At 4, 8, and 12 weeks, thicknesses of the fibrous tissue capsules in the experimental group were lower than in the control group. Likewise, the amount of collagen in the experimental group was lower than that of the control group. For the
in vitro cell culture experiments, KMST-6 fibroblast cells in the experimental group demonstrated enhanced cell migration, accompanied with a weaker expression of vinculin and a larger amount of filopodia. Furthermore, weaker expressions of paxillin, talin, and ROCK1, but stronger expression of cofilin, were observed in the experimental group. Taken together, these results suggested that MPC polymer regulated fibrous tissue formation by modulating cell adhesion through changes in local CAPs and downstream signaling.
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Tadao FUKUSHIMA, Jun OHNO, Tohru HAYAKAWA, Rieko IMAYOSHI, Minoru KAWA ...
2010 年 29 巻 5 号 p.
529-535
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/08/20
ジャーナル
フリー
The DNA/protamine complex was prepared by a reaction between DNA and protamine sulfate solutions with stirring, and its cell viability, antibacterial effect and histopathological responses were examined. A water-insoluble white powder, DNA/protamine complex, with a porous structure was obtained. The molar binding ratio of the complex prepared from a solution containing equal amounts of DNA and protamine sulfate by weight was 0.038 and the efficiency of complex formation was 61%. In a cell culture test using MC-3T3-E1 mouse osteoblast cells, the complex showed less cytotoxicity than protamine sulfate alone and cell viabilities were more than 98%. A porous disk could be prepared easily and showed an antibacterial effect against
Staphyrococcus aureus,
Porphyromonas gingivalis and
Prevotella intermedia in an antibacterial sensitivity test and a mild tissue response
in vivo test. These results suggested that the DNA/protamine complex could be a useful biodegradable biomaterial with antibacterial effects.
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Makoto NODA, Yuji OKUDA, Jiro TSURUKI, Yoshito MINESAKI, Yasumi TAKENO ...
2010 年 29 巻 5 号 p.
536-541
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/18
ジャーナル
フリー
The purpose of this study was to characterize the surface damages of zirconia by Nd:YAG dental laser irradiation through a systematic evaluation of the associated microstructural changes. Disk specimens of yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) and ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/Al
2O
3 nanocomposite) were irradiated by Nd:YAG dental laser. The specimens were characterized using scanning electron microscopy, X-ray diffractometry, and wavelength dispersive X-ray spectroscopy. Every single irradiated spot was indicated by a circular black pit surrounded by a circular raised rim with a sunken depression at the center. On surface changes, many cracks were formed inside each irradiated pit. On changes in elemental composition, the concentration of oxygen decreased while that of zirconium increased. After heating in air, the assembly of circular black pits turned white, although the depression and raised rim remained. This study showed that Nd:YAG dental laser irradiation induced cracking and reduced oxygen content on the surface of zirconia. Consequently, these phenomena reduced the mechanical strength of zirconia. Therefore, Nd:YAG dental laser welding should not be performed on tetragonal zirconia.
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Masatoshi YAMAZOE
2010 年 29 巻 5 号 p.
542-553
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/01
ジャーナル
フリー
Metal ions released in 1% lactic acid solution from combinations of titanium fixtures with superstructures made of dental precious metal alloys (dental alloys) and titanium and differences based on the fixing method were investigated. In combinations of titanium with dental alloys, the level of Ti release was influenced by micro-structure of titanium: it was lower when the grain size was smaller. In titanium-titanium combinations, differences in the micro-structure of metal also markedly influenced the dissolution: the level of release increased when the micro-structure of titanium was different. The Ti and V release levels were higher in combination with titanium alloy and titanium than with titanium alloy and dental alloys. Regarding the superstructure-fixture fixing method, the level of Ti release was significantly lower in cement than in direct fixation.
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Hiroshi MURATA, Guang HONG, Chiaki YAMAKADO, Tadafumi KUROGI, Hiroshi ...
2010 年 29 巻 5 号 p.
554-561
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/08/20
ジャーナル
フリー
Scant rheological information is available regarding home reliners (liner type denture adhesives). We evaluated 6 different home reliners in regard to their viscoelastic properties, water absorption and solubility. Dynamic viscoelastic properties and changes over time were determined using a dynamic viscoelastometer, while weight changes, absorption, and solubility during immersion in water were also investigated. We found that the dynamic viscoelasticity of the tested home reliners was sensitive to changes in frequency, while the materials used had nearly no elasticity and exhibited viscous behaviors. They showed a dramatic change in viscoelastic properties and increase in weight after approximately 1 day of water immersion. A considerably high percentage of water absorption was also observed. From the viewpoint of dynamic viscoelastic properties and durability, our results indicate that the tested home reliners would not be suitable for improvement of ill-fitting dentures.
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Meu ARIYOSHI, Toru NIKAIDO, Richard M. FOXTON, Junji TAGAMI
2010 年 29 巻 5 号 p.
562-569
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/08/20
ジャーナル
フリー
This study evaluated the influence of filling technique and curing mode on the microtensile bond strengths (MTBS) of composite cores to pulpal floor dentin. Access cavities of human molars with pulpal floor dentin were restored with a two-step self-etch adhesive system, Clearfil Liner Bond 2V and a composite core, Clearfil DC Core Automix, using different filling techniques and curing strategies. A flowable resin composite, Clearfil Flow FX was placed on the cured adhesive resin prior to restoration with a composite core. Packing the composite in the access cavity was performed in bulk with or without light curing or using an incremental technique with light curing. Microtensile bond strengths to pulpal floor dentin were measured after 24 hours storage in water. Light curing and incremental technique had positive effects on the MTBSs. Lining with a flowable resin composite did not significantly improve the MTBSs, however, influenced the failure mode after debonding. Non-lining and bulk filling with chemical curing strategy provided the lowest MTBS.
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Masayuki HATTORI, Shinji TAKEMOTO, Masao YOSHINARI, Eiji KAWADA, Yutak ...
2010 年 29 巻 5 号 p.
570-574
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/08/20
ジャーナル
フリー
The mechanical properties of a series of binary Ti-Cr alloys were investigated. Chromium content ranged from 5 to 20 mass%. Dumbbell- and disk-shaped specimens of each alloy were obtained by casting for mechanical testing and microstructural observation. Yield strength (YS) at 0.2%, tensile strength (TS), elongation (EL) and Vickers hardness (Hv) were determined. The TS and YS of Ti-15Cr were similar to those of Ti-20Cr at approximately 880 or 900 MPa and higher than those of cp-Ti by nearly 55%. Among all Ti-Cr alloys, Ti-10Cr showed the lowest EL. At 50 μm below the surface, Hv ranged from 370 to 420. Addition of 15 or 20 mass% chromium to titanium yielded sufficient strength and relatively high elongation values. Judging from the results of the mechanical properties, the suitability of Ti-Cr alloys with 15 or 20 mass% chromium for use in dental prostheses.
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Takahito KANIE, Akihiko KADOKAWA, Hiroyuki ARIKAWA, Koichi FUJII, Seij ...
2010 年 29 巻 5 号 p.
575-581
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/08/20
ジャーナル
フリー
Light-curing polyethyl methacrylate (PEMA)-urethane dimethacrylate (UDMA) resins and polymethyl methacrylate (PMMA)-UDMA resins were prepared by two processes. For first step, PEMA or PMMA powders were fully dissolved in ethyl methacrylate (EMA) or methyl methacrylate (MMA) and then the PEMA-EMA/PMMA-MMA mixtures were mixed with UDMA. The flexural properties of cured PEMA-UDMA and PMMA-UDMA polymers were measured using two PEMA (Mw: 300,000–400,000 and 650,000–1,000,000) and three PMMA (Mw: 30,000–60,000, 350,000 and 650,000–1,000,000) powders with different molecular weight, four mixing ratios of PMMA-MMA, and three mixing ratios of PMMA-MMA mixture and UDMA oligomer. Polymers with PMMA(Mw: 350,000) MMA=25/50, and with PMMA(Mw: 350,000)-MMA/UDMA=1/2 and =1/1, showed no-fracture in a flexural test at 1 mm/min and flexural strength and flexural modulus showed no significant difference compared with those of commercially available heat- and self-curing acrylic resins (
p>0.01). Within limitation of this investigation, methyl methacrylate-UDMA blend polymer of this composition is available for denture base resin.
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Yuki IMAMURA, Yumi TANAKA, Akiko NAGAI, Kimihiro YAMASHITA, Yuzo TAKAG ...
2010 年 29 巻 5 号 p.
582-588
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/08/20
ジャーナル
フリー
The densification process and canal sealing ability of octacalcium phosphate (OCP)-mediated cement were investigated for developing biocompatible and biodegradable root canal filling material for deciduous root. The results of the characterization revealed that the starting paste, which consisted of monocalcium phosphate monohydrate, calcium carbonate, and α-tricalcium phosphate, gradually transformed into carbonate apatite for 6 weeks of immersion in medium with 30% fetal bovine serum (MEM30). The canal sealing ability was estimated by dye penetration test. Three kinds of conditions were chosen for the test: one was the cement just after filling the single-rooted extracted human roots; the others were the cement aged in MEM30 for 1 and 6 weeks after filling, respectively. All roots were then immersed in India ink for 3 days. The penetration depth of OCP-mediated cement decreased significantly with time. This demonstrates that OCP-mediated cement has self-sealing ability.
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Jing LI, Yoshihito NAITO, Jian-Rong CHEN, Takaharu GOTO, Yuichi ISHIDA ...
2010 年 29 巻 5 号 p.
589-595
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/18
ジャーナル
フリー
The purpose of this study was to evaluate four luting agents for cement-retained implant restorations in two aspects: post-cementation elevation of the superstructure and the retentive strength before and after thermocycling and mechanical cycling. The four evaluated luting agents were: new glass polyalkenoate hard-type (GH) and soft-type (GS) cements, polycarboxylate hard-type (HH) and soft-type (HS) cements. Elevation and retentive strength were measured using a CCD laser displacement sensor and a universal testing machine respectively. Elevation increased in this order: GH, GS, HH, and HS. Thermal and mechanical stresses significantly decreased retentive strength, and the mean values exhibited by GH were significantly higher than the other luting agents. The novel glass polyalkenoate cements (hard- and soft-type) experimentally prepared in the present study augured well as luting agents by virtue of their reduced film thickness and their excellent post-cementation retention and elevation.
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Yoshiko KONDO, Tomohiro TAKAGAKI, Makoto OKUDA, Masaomi IKEDA, Yoshino ...
2010 年 29 巻 5 号 p.
596-601
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/07
ジャーナル
フリー
The aim of this study was to evaluate the effect of additional polymethyl methacrylate (PMMA) fillers on the physical properties of experimental resin composites. PMMA particles (d=30 μm) were added to an experimental methacrylate-based resin composite in five concentrations of 0, 2.0, 4.8, 9.1, and 23.1 wt%. Properties such as contact angle, water sorption and compressive strength were measured and the fractured specimens were observed with a scanning electron microscope. The results showed that a small amount (2 wt%) of additional PMMA fillers inhibited the crack propagation and enhanced compressive strengths of the resin composites, without a significant change in water contact angle of surface or increased water sorption. However, in higher portions, the mechanical properties were not improved as a debonding at the interface between untreated fillers and the matrix, or failure within the organic filler could reduce the compressive yield strength of the composite.
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Yoshinori KADOMA
2010 年 29 巻 5 号 p.
602-608
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/04
ジャーナル
フリー
The kinetic polymerization behavior of 2,2,2-trifluoroethyl methacrylate (TFEMA), 1,1,1,3,3,3-hexafluoroisopropyl methacrylate (HFIPMA), 2,2,2-trifluoroethyl acrylate (TFEA) and 1,1,1,3,3,3-hexafluoroisopropyl acrylate (HFIPA) was determined by isothermal differential scanning calorimetry (DSC) and high-performance liquid chromatography (HPLC) in order to improve the properties of fluorinated powder-liquid adhesive resins. Conversion and heat of polymerization were calculated, and the solubility of the homopolymers in common solvents was examined. Comparison of their polymerization reactivity with that of MMA revealed that the overall rate of polymerization initiated by benzoyl peroxide (BPO) decreased in the order TFEA>MMA>TFEMA>HFIPA>HFIPMA. Based on the retention time of the monomer determined by HPLC, the hydrophobicity of the monomers was found to increase in the order MMA<TFEA<TFEMA<HFIPA<HFIPMA. The overall research results suggested that TFEA and HFIPA would be potentially promising candidates for the monomer liquid component of fluorinated powder-liquid adhesive resins.
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Yuya NASU, Kazuo ITOH, Chihiro TANI, Hisashi HISAMITSU
2010 年 29 巻 5 号 p.
609-614
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/16
ジャーナル
フリー
The aim of this study was to investigate the diffusion of red-stained experimental GM primer and blue-stained dentin bonding agent into EDTA-conditioned dentin and the effect of GM priming on contraction gap formation. After GM priming at 0, 35, 70, or 100 vol%, marginal adaptation was evaluated by measuring the wall-to-wall contraction gap width of a light-activated resin composite (Palfique Estelite, Tokuyama Dental, Japan) mediated with a commercial dentin bonding agent (Clearfil Photo Bond, Kuraray Medical, Japan). Contraction gap formation was completely prevented when treated with 35 vol% GM primer. Moreover, after treatment with 35 vol% GM, the red and blue dyes of stained GM primer and dentin bonding agent diffused up to a depth of 40 μm into the dentin surface. The diffusion of primer and bonding agent into EDTA-conditioned dentin was essential for bonding efficacy although SEM observation revealed an absence of hybrid layer formation.
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Rena TAKAHASHI, Toru NIKAIDO, Meu ARIYOSHI, Shuzo KITAYAMA, Alireza SA ...
2010 年 29 巻 5 号 p.
615-622
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/01
ジャーナル
フリー
This study was evaluated the tensile bond strength (TBS) of resin cements to bovine dentin resin-coated with all-in-one adhesive systems. Each of the dual-polymerizing resin cements; Link Max, Clearfil Esthetic Cement, Bistite II and Chemiace II were used to bond indirect resin disks to bovine dentin, as control, or coated by single-application or by dual-application of an adhesive system from the same manufacturer; G-Bond, Clearfil Tri-S Bond, Tokuyama Bond Force and Hybrid-Coat (
n=10). After 24-hour water storage, TBSs were measured. The fracture pattern and the adhesive interface were observed using an SEM. Dual-application of the adhesive yielded significantly higher TBSs compared to control and single-application groups for all materials (
p<0.001). From the limited information of this study, it was concluded that dual-application of all-in-one adhesive systems created a thin coating on dentin, and significantly improved the bond strengths of resin cements.
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Shima ITOH, Masatoshi NAKAJIMA, Keiichi HOSAKA, Masako OKUMA, Masahiro ...
2010 年 29 巻 5 号 p.
623-630
発行日: 2010年
公開日: 2010/10/14
[早期公開] 公開日: 2010/09/01
ジャーナル
フリー
The purpose of this study was to evaluate the dentin bonding durability of three HEMA-containing one-step self-etch adhesives after one-year water storage and to measure the amounts of their water sorption/solubility. OptiBond All-In-One (OP), Bond Force (BF) and Clearfil S
3 Bond (S
3) were applied to the dentin surfaces according to manufacturers’ instructions. Bond strengths to dentin were determined using μTBS test after water storage for 24 hours, six months, and one year. In addition, water sorption and solubility of the polymerized adhesives were measured. The μTBS of S
3 and OP significantly decreased after one year. On the other hand, for BF there were no significant differences in μTBS between all storage periods. There were significant differences in water sorption and solubility among the adhesives (BF>S
3>OP). The initial amounts of water sorption and solubility of the three adhesives did not affect their bonding durability to dentin.
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