Dental Materials Journal
Online ISSN : 1881-1361
Print ISSN : 0287-4547
ISSN-L : 0287-4547
24 巻, 4 号
選択された号の論文の28件中1~28を表示しています
  • Nicoleta ILIE, Karl-Heinz KUNZELMANN, Anuradha VISVANATHAN, Reinhard H ...
    2005 年 24 巻 4 号 p. 469-477
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The purpose of this study was to analyze the curing behavior of a nanocomposite by assessing in real time the degree of cure at depths of 2mm and 6mm. The variation of hardness with depth, shrinkage stress, and curing time until gelation with 16 curing regimes was further investigated using one halogen and three LED curing units.
    In the present study, it was shown that the soft-start polymerization concept is still valid, even with high-power LED curing units. A soft cure polymerization resulted in reduced shrinkage stress while simultaneously keeping the degree of cure and mechanical properties constant. For all tested curing unit types, a short polymerization duration (10 seconds) was insufficient to cure the nanocomposite in deeper layers-since the variation of hardness with depth showed a discontinuity between the layers, thus accounting for a decreased hardness of up to 30%.
  • Wei WANG, Mamoru OMORI, Fumio WATARI, Atsuro YOKOYAMA
    2005 年 24 巻 4 号 p. 478-486
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    Novel, bulk multiwall carbon nanotubes (MWCNTs) sintered with polycarbosilane (PCS) as a binder agent were fabricated by spark plasma sintering (SPS), and their microstructure and properties were investigated. Sintering was done with 20-60MPa pressure at 1200°C. SEM and TEM observations showed that the nanosized tube microstructure was preserved even after sintering, and tubes adhered to each other with the nanosized nodules of SiC pyrolyzed form PCS as revealed by X-ray diffraction. Bulk density and Vickers hardness were found to increase, whereas the specific surface area decreased, as PCS content and sintering pressure increased. Through animal experiments, the inflammatory reaction of CNTs/PCS material was found to be slightly increased with increasing PCS content. In conclusion, sintered CNTs had physical and mechanical properties close to bone, and their good biocompatibility based on tissue response served to pave their way as a suitable implant material in the future.
  • Takahiro ONO, Kaori ISHIKAWA, Osamu YAMABA, Takashi NOKUBI
    2005 年 24 巻 4 号 p. 487-493
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    In a previous report, we investigated the influence of the shooting angle of polishing particle on the surface roughness of a cobalt-chromium (Co-Cr) alloy using a centrifugal shooting type polishing machine. In the present work, we examined the effects of the texture of polishing particle and polishing time on the surface roughness of Co-Cr alloy cast specimens. Nine different textures of polishing particle were investigated with respect to core material and particle abrasiveness: three different elastic body cores (core A, hard chloroprene rubber; core B, soft chloroprene rubber; core C, natural rubber) and three different green carborundum powders as abrasives (#800, #3000, and #6000). Polishing was performed under a fixed shooting angle of 30° for six different polishing times (1, 2, 3, 5, 7, and 10 minutes). Surface roughness (Ra, Sm) and cutting depth on the polished surface were measured after each polishing stage. Surface roughness was significantly improved within three minutes, particularly using a polishing particle with rough carborundum powder (#800 or #3000) and a heavy core (core A or core B). Cutting depth increased in proportion to polishing time and roughness of carborundum powder, and was least with core C. These results suggested that a polishing particle composed of core B and #3000 carborundum paste was superior for the intermediate polishing of a Co-Cr alloy, and that polishing time should be limited to within three minutes.
  • Yoshinori KADOMA, Katsunori KOJIMA
    2005 年 24 巻 4 号 p. 494-502
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    Adhesive resins for precious metals were prepared by adding an adhesion promoting monomer to MMA-PMMA/TBBO resin. Precious metal alloys bonded by the adhesive resin were thermocycled 0, 1, 000, 2, 000, or 4, 000 times in water between 4 and 60°C, and tensile bond strengths were measured. Debonded metal surfaces after the tensile test were analyzed based on an area of cohesive failure.
    Three-way ANOVA revealed that all the three parameters—adherend, adhesive monomer, and number of thermal cycles —exhibited a significant influence on bond strength. Bond strength significantly decreased with increasing number of thermal cycles except for resin with 9, 10-epithiodecyl 4-vinylbenzoate (EP8VB) to Au alloy. Mean bond strength of adhesive resin with 9, 10-epithiodecyl methacrylate (EP8MA), EP8VB, or 3, 4-epithiobutyl 2, 2-bis (methacryloyloxymethyl) propionate (EP2BMA) exceeded 22MPa after 4, 000 thermal cycles. Analysis of debonded surfaces revealed the applicability of EP8MA, EP8VB, and EP2BMA as an adhesive monomer component of adhesive resin formulations.
  • Hiroki OHNO, Kazuhiko ENDO, Katsumi HANEDA, Makoto TAMURA, Kazuhiro HI ...
    2005 年 24 巻 4 号 p. 503-507
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    Gold alloys with Cu contents of 10mass%, 20%, and 30% were used for morphological observation of porous surface structures after heating at 800°C in air followed by pickling with acid solution. With increasing Cu content in the gold alloy, the internal oxidation zone became well-developed in the alloy matrix. The mechanism by which a porous structure was formed on the surface of a gold alloy containing only Cu as a base metal was thought to be as follows: Cu2O which formed along the grain boundaries acted as a diffusion path, permitting the penetration of O2- into the inner alloy matrix, and thereby resulting in internal oxidation occurring predominantly along the grain boundaries.
  • Masayuki OKAZAKI, Isao HIRATA, Takuya MATSUMOTO, Junzo TAKAHASHI
    2005 年 24 巻 4 号 p. 508-514
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The chemical analysis of hydroxyapatite and fluorapatite was carried out using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Hydroxyapatite and fluorapatite were synthesized at 80±1°C and pH 7.4±0.2. Fluorapatite was better crystallized, with its (300) reflection shifted to a slightly higher angle. High-resolution transmission electron microscopy clearly revealed a typical, regular hexagonal cross section perpendicular to the c-axis for fluorapatite and a flattened hexagonal cross section for hydroxyapatite. FT-IR spectra of fluorapatite confirmed the absence of OH absorption peak—which was seen in hydroxyapatite at about 3570cm-1. TOF-SIMS mass spectra showed a peak at 40 amu due to calcium. In addition, a peak at 19 amu due to fluorine could be clearly seen, although the intensities of PO, PO2, and PO3 were very low. It was confirmed that TOF-SIMS clearly showed the differences between positive and negative mass spectra of hydroxyapatite and fluorapatite, especially for F- We concluded that TOF-SIMS exhibited distinct advantages compared with other methods of analysis.
  • Yumiko SUZUKI, Shigeki MATSUYA, Koh-ichi UDOH, Masaharu NAKAGAWA, Yosh ...
    2005 年 24 巻 4 号 p. 515-521
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The aim of this study was to evaluate the feasibility of fabricating low-crystalline, porous apatite block using set gypsum as a precursor based on the fact that apatite is thermodynamically more stable than gypsum. When the set gypsum was immersed in 1mol/L diammonium hydrogen phosphate aqueous solution at 100°C, it transformed to low-crystalline porous apatite retaining its original shape. The transformation reaction caused a release of sulfate ions due to an ion exchange with phosphate ions, thus leading to a decrease in the pH of the solution. Then, due to decreased pH, dicalcium phosphate anhydrous—which has similar thermodynamic stability at lower pH—was also produced as a by-product. Apatite formed in the present method was low-crystalline, porous B-type carbonate apatite that contained approximately 0.5wt% CO3, even though no carbonate sources—except carbon dioxide from air—were added to the reaction system. We concluded therefore that this is a useful bone filler fabrication method since B-type carbonate apatite is the biological apatite contained in bone.
  • Toshiyuki SUGE, Akiko KAWASAKI, Kunio ISHIKAWA, Takashi MATSUO, Shigey ...
    2005 年 24 巻 4 号 p. 522-529
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The aim of this study was to evaluate the occluding ability of calcium phosphate precipitation (CPP) method and potassium oxalate treatment when each method was applied to dentin disks with different surface morphology. Occluding ability was observed by scanning electron microscopy. Irrespective of the diameter of the dentinal tubules, the CPP method showed a consistent occluding ability for dentinal tubules at the dentin surface, and that the depths of the precipitate formed in the dentinal tubules by CPP method were not significantly different. In contrast, the occluding ability of potassium oxalate treatment was reduced with increasing diameter of the dentinal tubules. However, the reduction of the occluding ability of potassium oxalate treatment was more markedly affected by the demineralization of dentin surface. Since the CPP method showed a consistent occluding ability irrespective of the diameter of the dentinal tubules, it is suggested that the CPP method would be a useful means for treating dentin hypersensitivity.
  • Tetsuya SUZUKI, Hidekazu TAKAHASHI, Mansuang ARKSORNNUKIT, Nobusuke OD ...
    2005 年 24 巻 4 号 p. 530-535
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The purpose of this study was to evaluate the shear bonding strength and leakage of heat-polymerized denture base resin to titanium-aluminum-niobium (Ti-6Al-7Nb) and cobalt-chromium (Co-Cr) castings using four adhesive systems; three adhesive primers (Metal Primer II, Metal Link, MR. Bond) and one heat-polymerized adhesive resin containing 4-META (Metadent). The resin tab was heat-polymerized directly with or without the primer. Shear bonding strengths and dye penetration distances were determined before and after 10, 000 times of thermocycling. The results were analyzed with three-way ANOVA and Tukey's comparison (p<0.05). Thermocycling significantly decreased bonding strength and promoted dye penetration. However, with the application of adhesive systems, post-thermocycling bond strength was significantly improved and dye penetration was inhibited. The bonding strength of Ti-6Al-7Nb was significantly smaller than that of Co-Cr, but the difference was marginal. These results suggested that the examined adhesive systems significantly improved the bonding efficiency of heat-polymerized resin to Ti-6Al-7Nb and Co-Cr alloys.
  • Yasuhiko ABE, Kyou HIASA, Maho TAKEUCHI, Yasuhiro YOSHIDA, Kazuomi SUZ ...
    2005 年 24 巻 4 号 p. 536-540
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The purpose of this study was to investigate a new biochemical surface modification technique for titanium implants using phospho-amino acid. Pure titanium disks were pretreated with 10N HCl and ultrapure water at room temperature for 30 minutes respectively. Then these disks were modified with either L-threonine (Thr) or O-phospho-L-threonine (P-Thr) at 37°C for 12 hours. X-ray photoelectron spectroscopy (XPS) chemically analyzed the modified surfaces. It was revealed that the N is peak which originated from Thr was not detected in the wide-scan spectrum of Thr-modified surface, whereas three peaks of N 1s, P 2s, and P 2p which originated from P-Thr were detected in the wide-scan spectrum of P-Thr-modified surface. Moreover, the P 2p peak of P-Thr which reacted with the surface significantly shifted to a lower binding energy (p<0.05). Based on the results of this study, it was concluded that P-Thr chemically bonded to the titanium surface treated with HCI.
  • Viritpon SRIMANEEPONG, Takayuki YONEYAMA, Equo KOBAYASHI, Hisashi DOI, ...
    2005 年 24 巻 4 号 p. 541-549
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    Mechanical properties of laser-welded castings of Ti-6Al-7Nb alloy, CP Ti, and Co-Cr alloy were investigated and compared to the unwelded castings using a tensile test. Dumbbell-shaped specimens were cut at the center, and two halves of the specimens were welded with an Nd: YAG laser welding machine at 220 or 260V of laser voltage. The mechanical strength of 260V groups was higher than that of 220V groups for Ti-6Al-7Nb and Co-Cr alloys except for CP Ti. All 260V laser-welded castings of Ti-6Al-7Nb alloy and CP Ti, which fractured outside the welded joints, exhibited ductile characteristics, while all laser-welded Co-Cr alloy castings, which fractured within the welded joints, showed brittle characteristics. This study proved that the mechanical strength of laser-welded Ti-6Al-7Nb alloy and CP Ti castings was as high as that of unwelded castings, while the mechanical properties of laser-welded alloy joints were influenced by microstructural changes.
  • Naoki BABA, Ikuya WATANABE, Yasuhiro TANAKA, Kunihiro HISATSUNE, Mitsu ...
    2005 年 24 巻 4 号 p. 550-554
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    This study investigated the joint properties of Fe-Pt alloy laser-welded to Co-Cr alloy. Cast plates (0.5×3.0×10mm) were prepared with Fe-Pt and Co-Cr alloys. Fe-Pt plates were butted against Co-Cr plates and laser-welded using Nd: YAG laser. Control and homogeneously welded specimens were also prepared. Laser welding was performed with and without argon shielding. Tensile testing was conducted, and both fracture force (Ff: N) and elongation (El: %) were recorded. There were no differences in the Ff value between the specimens with and without argon shielding for the welded Fe-Pt/Co-Cr. Lower Ff value of the welded specimen was obtained in the order of Fe-Pt alloy<Fe-Pt/Co-Cr<Co-Cr alloy. The results indicated that Fe-Pt welded to Co-Cr had Ff values between the values of homogeneously welded Fe-Pt and Co-Cr alloys. Argon shielding, on the other hand, had no effect on the weld strength between Fe-Pt and Co-Cr alloys.
  • Masatoshi TAGAYA, Hirosuke GOTO, Mitsuo IINUMA, Nobukazu WAKAMATSU, Ya ...
    2005 年 24 巻 4 号 p. 555-561
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    As an alternative to calcium hydroxide used as a direct capping agent, calcium phosphate cement that consisted of tetracalcium phosphate and α-tricalcium phosphate (Te-CP/α-TCP) at different molar ratios was developed with a one-step method, in which heating was performed only one time. Alkalinity could be adjusted easily by changing the Te-CP/α-TCP ratio, whereby the mixing ratio of simple chemicals such as calcium carbonate and dicalcium phosphate dehydrate was changed. When mixed with a solution of 1mol/L sodium dihydrogen phosphate, the cement set forming carbonatecontaining apatite in revised, simulated body fluid (R-SBF) — which served to mimic the tissue fluid in dental pulp. The pH of the solution never exceeded 8.0 in the presence of the set cement even after about one month of storage. In contrast, with calcium hydroxide, the pH of R-SBF reached almost 12.0 on day 1 and remained at that value till the end of immersion. These findings clearly suggested that with Te-CP/α-TCP cement, its alkalinity would never exceed that of calcium hydroxide and that it would provide a mildly alkaline environment.
  • Bor-Shiunn LEE, Hsin-Yi TSAI, Yi-Ling TSAI, Wan-Hong LAN, Chun-Pin LIN
    2005 年 24 巻 4 号 p. 562-569
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    Sealing of exposed dentinal tubules is generally considered the most effective strategy to treat dentin hypersensitivity. On this account, we fabricated a DP-bioglass paste that created a homogeneous blockage on open dentinal tubules and formed a deep precipitate within dentinal tubules. DP-bioglass paste was prepared by mixing 20% to 60% phosphoric acid and DP-bioglass to treat dentin surfaces. CO2 laser irradiation was used to melt the DP-bioglass paste. The results demonstrated that 30% phosphoric acid was the optimum concentration to produce homogeneous occlusion on exposed dentinal tubules and 60μm of sealing depth. CO2 laser irradiation could melt the DP-bioglass paste and create about 10μm of sealing depth. Moreover, temperature rise during CO2 laser irradiation was only 4.86±0.47°C. The results presented in this work suggested that DP-bioglass paste could produce considerable sealing depth in dentinal tubules with the potential of prolonging the therapeutic effect efficaciously.
  • Hiroki NIKAWA, Kazuhiro ISHIDA, Taizo HAMADA, Takahiro SATODA, Takeshi ...
    2005 年 24 巻 4 号 p. 570-582
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The aim of our study was twofold: to immobilize an organosilicon quaternary ammonium salt (3-(trimethoxysilyl)-propyldimethyl-octadecyl ammonium chloride, Si-QAC) on the surface of pure titanium and to investigate the antimicrobial activity of Si-QAC-immobilized titanium against microbial adherence and biofilm formation. The results of ToF-SIMS analysis of Si-QAC-titanium suggested the possibility of immobilizing Si-QAC on titanium surface through Ti-O-Si coupling, and that Si-QAC treatment significantly reduced both the adherence and colonization of Candida albicans and Streptococcus mutans isolates. The antimicrobial activity was achieved through at least two mechanisms: the first was attributed to the octadecyl alkyl chain which inhibited initial adherence, and the second was attributed to the quaternary ammonium salt which killed initial adherent cells as well as retarded or inhibited subsequent microbial growth. Further, thermocycling did not significantly reduce the antimicrobial activity of Si-QAC-titanium, and no significant cytotoxicity of Si-QAC-titanium was observed in either cell viability test or proinflammatory cytokine production test using human gingival fibroblasts. These results, taken together, favorably suggested that Si-QAC treatment would be a helpful means to inhibit dental plaque or denture plaque formation.
  • Yohsuke TAIRA, Maki SHIMODA, Kumiko ABE, Kohyoh SOENO, Mitsuru ATSUTA
    2005 年 24 巻 4 号 p. 583-587
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The purpose of this study was to investigate the effect of phosphoric acid etching on the bond strength between enamel and three luting materials employing self-etching primer (PanaviaF2.0, Linkmax, and Multibond). A luting material without self-etching primer (Super-Bond) was used as a control. Two etching agents (K-etchant and Red Activator) were prepared. The surfaces of bovine enamel were ground, etched with either K-etchant or Red Activator, and then bonded to a stainless steel rod. Tensile bond strengths were determined following 24-hour immersion in water. Without etching, all of the luting materials showed the same statistical bond strength. When K-etchant was applied, the bond strengths of PanaviaF2.0, Linkmax, Multibond, and Super-Bond were significantly greater than that of non-etched control. No significant differences were found between K-etchant and Red Activator. Strongest bonds were obtained for Super-Bond in conjunction with K-etchant (23.6±6.3MPa) or Red Activator (21.0±6.5MPa), whereby the values were statistically comparable.
  • Akihiko YUDA, Seiji BAN, Yuichi IZUMI
    2005 年 24 巻 4 号 p. 588-595
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The hydrothermal-electrochemical method is best suited for producing homogeneous apatite coatings on electro-conductive materials with complicated shape, such as the mesh. This study was undertaken to examine the effect of the apatite coating prepared by this coating method on cell adhesion, proliferation, and differentiation of MC3T3-E1 cells in culture. The cells attached and spread well on the electrochemically deposited apatite on titanium mesh. The number of cells that adhered on the deposited apatite on titanium mesh was much greater than that on the surface without coating, and that it also depended on the morphology of apatites. When alkaline phosphatase activity as well as collagen and osteocalcin of the extracellular matrix were measured, the electrochemically apatite-coated titanium mesh showed higher measurement values than the titanium mesh without coating. These results suggested that the apatite-coated titanium mesh prepared by hydrothermal-electrochemical method has excellent biocompatibility.
  • Jung-Ho KIM, Oh-Won KWON, Hyung-Il KIM, Yong Hoon KWON
    2005 年 24 巻 4 号 p. 596-602
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The purpose of this study was to test the effectiveness of an Er: YAG laser in etching the enamel surface for orthodontic treatment. Bovine incisors were either acid-etched or laser-treated. An orthodontic bracket was attached on each treated surface using one-step dentin adhesive and self-curing resin. Tensile bond strength was then evaluated. In addition, the surface morphology of specimens treated with phosphoric acid/laser and self-etching primer, as well as the cross-section of enamel-primer-resin interfaces, were observed. One-Up Bond F-treated specimens after Er: YAG laser ablation showed statistically similar tensile bond strength (9.9±1.3MPa) to that of phosphoric acid-etched specimens (11.8±1.7MPa). Surface roughness and thickness of the enamel-primer-resin interfaces did not much affect the tensile bond strength of the tested specimens. In conclusion, Er: YAG laser ablation achieved clinically acceptable level of tensile bond strength when used with One-Up Bond F.
  • Norihiro YAMADA, Ken MIYAZAWA, Hideyuki MIWA, Masako TABUCHI, Takamasa ...
    2005 年 24 巻 4 号 p. 603-609
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The aims of this study were to examine the enamel protective effect of a direct laminate veneer against acidic conditions, measure the amount of fluoride released from the veneer and which was taken up by the enamel, as well as evaluate the usefulness of the veneer for orthodontic treatment. First, a veneer was applied to rabbit incisors. Then, apart from using profile measurement microscope and electron probe microanalyzer to measure the roughness and fluoride concentration in the enamel of veneer-covered tooth surface, those of the uncovered adjacent tooth surface were measured too. It was found that the veneer protected the enamel surface from acidic conditions. Furthermore, fluoride ions were taken up by both the uncovered adjacent enamel area as well as by the covered area. These findings suggested that covering the enamel surface with a direct laminate veneer before bracket bonding might be a valuable means of tooth protection and caries prevention.
  • Yukyo TAKADA, Osamu OKUNO
    2005 年 24 巻 4 号 p. 610-616
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    A series of binary Ti-Cu alloys containing 5-20 mass% Cu was prepared, and the corrosion behavior of α-Ti and Ti2Cu composing the Ti-Cu alloys were examined based on the anodic polarization curves and released ions in 0.9% NaCl and 1% lactic acid solutions. In both solutions, the Ti-Cu alloys showed the same anodic polarization curves as titanium in the condition below 1.4 V. However, precipitation of Ti2Cu contributed to a small increase in current densitiy in the transpassive region beyond 1.4 V. The amount of Cu ions released from Ti2Cu was 0.260 and 1.003 (μg/cm2/7 days) in 0.9% NaCl and 1% lactic acid solutions respectively. Although these values were larger than those from α-Ti (0.0379±0.0041 and 0.0962±0.0327 (μg/cm2/7days) in NaCl and lactic acid solutions respectively), they were not greater than those from type 4 gold alloy under the same conditions.
  • Wataru SASAKAWA, Yasuko NAKAOKI, Futami NAGANO, Seiko HORIUCHI, Takats ...
    2005 年 24 巻 4 号 p. 617-627
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The micro-shear bond strengths (MSBSs) of five single-step self-etch adhesives (Adper Prompt L-Pop [APL], AQ Bond plus [AQP], OBF-2 [OB2], Reactmer Bond [RB], and Xeno III [XIII]) were compared with that of a two-step self-etch adhesive, Clearfil SE Bond [SE]. The adhesives were applied on dentin surfaces, according to manufacturers' instructions, for bonding of resin composite to dentin. After 24 hours, a micro-shear bond test was carried out and the data were analyzed by oneway ANOVA and Bonferroni test (p<0.05). The mean MSBSs in MPa were APL: 22.8, AQP: 37.4, OB2: 34.7, RB: 28.3, XIII: 30.3, and SE: 47.2. Among the single-step adhesives, the MSBS of AQP and OB2 were significantly higher than APL (p<0.05). In conclusion, the single-step adhesives used in this study, apart from AQP, produced significantly lower MSBS than the two-step adhesive (p<0.05).
  • Taiju AOKI, Kiyotaka OGAWA, Ken MIYAZAWA, Tatsushi KAWAI, Shigemi GOTO
    2005 年 24 巻 4 号 p. 628-635
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The purpose of this study was to investigate the possibility of using a bioabsorbable implant as orthodontic anchorage. The implant under investigation in this study was a miniscrew, 2.0mm×8.0mm, made from poly-L-lactic acid (PLLA; molecular weight: 200, 000), a bioabsorbable bone-bonding material. The implants were placed in the mandibles of eight male beagle dogs. After implantation, traction was immediately applied to the third premolar (P3) using the implant as anchorage. After the completion of each study period (three and six months) following installation, tensile test, histological examination, and molecular weight measurement were performed. The results suggested that the bioabsorbable implant evaluated had favorable biocompatibility and strength, and that it showed promising potential for use in orthodontic treatment.
  • Hiroyuki ARIKAWA, Takahito KANIE, Koichi FUJII, Seiji BAN
    2005 年 24 巻 4 号 p. 636-641
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The purpose of this study was to investigate the effect of radiation light characteristics — of different types of clinical light-curing unit — on polymerization efficiency, as determined by the surface hardness of light-cured paint-on resins. Four shades of paint-on resin for shade modification of restorative resins were used. Materials were cured using one laboratory and three clinical light-curing units with different light sources, namely tungsten-halogen, LED, plasma arc, and xenon flash lamps. Knoop hardness measurements were taken at both the top and bottom surfaces of the specimens to assess the mechanical properties and degree of polymerization. Both LED and plasma arc light units caused significantly poorer surface hardness than the halogen and laboratory xenon lights. In addition, the transparent shade was more sensitive to surface hardness than other chromatic shades. Our results indicated that the polymerization efficiency of paint-on resin was significantly influenced by the radiation light characteristics of clinical light-curing units.
  • Yumi ISHIKAWA, Yoshikazu KAWAMOTO, Mika NEMOTO, Hiroyasu KOIZUMI, Kimi ...
    2005 年 24 巻 4 号 p. 642-647
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The purpose of this study was to evaluate the effect of acidic primers on bonding magnetic steel alloys. Three alloys (XM27, 447J1, and AUM20) were primed with one of the following materials: Acryl Bond, Estenia Opaque Primer, Eye Sight Opaque Primer, M. L. Primer, or Super-Bond liquid. The specimens were bonded with a tri-n-butylborane initiated resin, and bond strength was determined both before and after thermocycling in water. Unprimed specimen was considered as the control. Average bond strength varied from 0 to 45.3MPa for the XM27 alloy, 0.3 to 43.6MPa for the 447J1 alloy, and 0.5 to 41.1MPa for the AUM20 alloy. Of the five primers, Estenia Opaque Primer exhibited better adhesive performance than the other materials regardless of the type of steel alloy. It can be concluded that the use of the Estenia Opaque Primer, which contains an adhesive monomer (10-methacryloyloxydecyl dihydrogen phosphate; MDP), is recommended for bonding the three magnetic steel alloys with TBB-initiated resin.
  • Lei ZHENG, Masatoshi NAKAJIMA, Takashi HIGASHI, Richard M. FOXTON, Jun ...
    2005 年 24 巻 4 号 p. 648-653
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    This study investigated the changes in hardness and Young's modulus of the transparent layer of dentin associated with aging and the carious process. Eighteen extracted human molars with or without coronal caries were used in this study. The normal teeth were divided into two groups by age, and the carious teeth were divided into two groups of active or arrested caries. After polishing the specimens parallel to the long axis of the tooth, both hardness and Young's modulus were measured using a nanoindentation tester. The hardness and Young's modulus of the transparent layer in aged dentin were higher than the other portions of aged dentin. The transparent layer under carious lesions had a significantly lower hardness than the underlying normal dentin, whereas its Young's modulus was not significantly reduced. The hardness and Young's modulus of the transparent layer in active carious lesions were lower than those in arrested carious lesions.
  • Shino AMANO, Takeshi YOSHIDA, Hirohiko INAGE, Toshiki TAKAMIZAWA, Akit ...
    2005 年 24 巻 4 号 p. 654-660
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The purpose of this study was to evaluate the adhesive performance of luting cements to a noble metal alloy treated with metal conditioners. Cast disk specimens made of a noble metal alloy were gritblasted with alumina followed by no treatment or priming with two different types of metal conditioner. A mold was placed on the metal surface and filled with luting cement. Ten samples per test group were stored in 37°C distilled water for 24 hours, then shear tested at a cross-head speed of 1.0mm/minute. ANOVA and Tukey's HSD tests (α=0.05) were done. The mean bond strength of resin-modified glass ionomer cement increased significantly with metal conditioner application compared to the controls, indicating the efficacy of the tested metal conditioners in improving bond strength. Based on the results of this study, it seemed to be a useful method to incorporate a functional monomer into resin cements so as to improve the bond strength to a noble metal alloy.
  • Soichiro KINUTA, Kazumichi WAKABAYASHI, Taiji SOHMURA, Tetsuya KOJIMA, ...
    2005 年 24 巻 4 号 p. 661-666
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    The aim of this study was to confirm the precision of our simple and inexpensive jaw tracking system which combined the use of a digital camcorder and a motion capture software developed lately. A marker was attached to the mandibular incisors of the subject, and a mirror was assembled beside the subject's face to detect antero-posterior movement during chewing. Jaw movements, including the mirror images, were recorded by a digital camcorder. The movements were traced by a motion capture software and translated into 3D data using original handmade software. To confirm the beneficial performance of our system in measuring masticatory movement, the masticatory movements of five subjects were simultaneously recorded together with a conventional jaw tracking system. Trajectories obtained from both systems were similar, and the correlation coefficient values by simple regression analysis between both trajectories were 0.9 or higher for all subjects. It was confirmed that our system could record masticatory movement with sufficient precision equivalent to that of a conventional jaw tracking system.
  • Koichi FUJII, Hiroyuki MINAMI, Hiroyuki ARIKAWA, Takahito KANIE, Seiji ...
    2005 年 24 巻 4 号 p. 667-675
    発行日: 2005年
    公開日: 2010/02/24
    ジャーナル フリー
    To evaluate the ease of manipulation and durability of 11 commercially available silicone-based resilient denture liners, extrusion force, hardness, weight change, and bond strength were determined. Extrusion force from the cartridge of each material ranged from 0.25 to 1.26MPa at an extrusion rate of 1cm/min. Durometer hardness, after set materials were stored in distilled water at 37°C for one day, ranged from A5.9 to A47.7, and after four weeks their values increased by 4.0 to 275%. Bond strength ranged from 1.01 to 2.88MPa after set materials were stored in distilled water at 37°C for one day, but decreased to 0.59 to 1.99MPa after 10, 000 thermal cycles. These results suggested that except for one material, the rest of the evaluated materials exhibited good handling properties — for example, mixing and spreading of material can be done easily. However, some materials exhibited inadequate durability for clinical service, because hardness increased during storage and/or bond strength decreased after thermal cycling.
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