Dental Materials Journal
Online ISSN : 1881-1361
Print ISSN : 0287-4547
ISSN-L : 0287-4547
27 巻, 1 号
選択された号の論文の20件中1~20を表示しています
Original papers
  • Makiha SHINYA, Akikazu SHINYA, Lippo V. J. LASSILA, Harunori GOMI, Juh ...
    2008 年 27 巻 1 号 p. 1-6
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    The chief aim of this study was to evaluate the influence of three different types of pretreatment solutions (phosphoric acid, self-etching primers, and polyacrylic acid) on enamel surfaced when used in association with one of the five orthodontic adhesive systems. In the same vein, the shear bond strength of orthodontic metal brackets was also measured to evaluate the influence of bonding procedure. After the enamel surfaces of extracted human maxillary incisors were pretreated with the five adhesive systems, scanning electron microscopy (SEM) was used to observe the effects of pretreatment on enamel. Additionally, the shear bond strength of metal brackets bonded with the five adhesives was measured (n=6). SEM observation revealed different etching patterns on the enamel surface after pretreatment. As for shear bond strength, no statistically significant differences were observed among the five different adhesives (p>0.05). It was found that self-etching primers and polyacrylic acid produced a less aggressive etching pattern than phosphoric acid. Nonetheless, all the five adhesive systems provided acceptable bond strength and attachment of orthodontic brackets.
  • Vanessa VÁSQUEZ, Mutlu ÖZCAN, Renato NISHIOKA, Rodrigo SOU ...
    2008 年 27 巻 1 号 p. 7-15
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    This study evaluated the effects of mechanical and thermal cycling on the flexural strength (ISO 9693) of three brands of ceramics fused to commercially pure titanium (cpTi). Metallic frameworks of 25×3×0.5 mm dimensions (N=84) were cast in cpTi, followed by 150-μm aluminum oxide airborne particle abrasion at a designated area of the frameworks (8×3 mm). Bonder and opaque ceramic were applied on the frameworks, and then the corresponding ceramic (Triceram, Super Porcelain Ti-22, Vita Titankeramik) was fired onto them (thickness: 1 mm). Half of the specimens from each ceramic-metal combination were randomly tested without aging (only water storage at 37°C for 24 hours), while the other half were mechanically loaded (20,000 cycles under 10 N load, immersion in distilled water at 37°C) and thermocycled (3,000 cycles, between 5—55°C, dwell time of 13 seconds). After the flexural strength test, failure types were noted. Mechanical and thermal cycling decreased the mean flexural strength values significantly (p<0.05) for all the three ceramic-cpTi combinations tested when compared to the control group. In all the three groups, failure type was exclusively adhesive at the opaque ceramic-cpTi interfacial zone with no presence of ceramic on the substrate surface except for a visible oxide layer.
  • Tomonaga WATANABE, Satoshi INO, Shusaku OKADA, Yuki KATSUMATA, Naho HA ...
    2008 年 27 巻 1 号 p. 16-20
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    This study evaluated the effectiveness of a simplified silica coating method (CoJet System) on the bonding strength of resin cements to dental alloy. Bonding strength of the specimens treated with metal primer after alumina sandblasting was compared with those treated with silica coating and silane coupling agent after alumina sandblasting. Furthermore, the influence of silane coupling agent on bonding strength was compared between one-liquid and two-liquid silane coupling agents.
    Measurement of shear bond strength before and after thermal cycling revealed that the group treated with silica coating in one step without alumina sandblasting yielded high bonding strength. As for the influence of silane coupling agent, treatment with two-liquid silane coupling agent achieved higher mean shear bond strength than with one-liquid silane coupling agent. Findings in this study indicated that silicatization by means of this simplified silica coating method was effective in improving the bonding strength to dental alloy.
  • Hiroyuki ARIKAWA, Takahito KANIE, Koichi FUJII, Hideo TAKAHASHI, Seiji ...
    2008 年 27 巻 1 号 p. 21-28
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    This study investigated the characteristics of output light from different types of light curing units, and their effects on polymerization of light-activated composite resin. Three quartz-tungsten-halogen lamps, one plasma arc lamp, and one LED light curing unit were used. Intensity distribution of light emitted from the light guide tip was measured at 1.0-mm intervals across the guide tip. Distribution of Knoop hardness number on the surface of resin irradiated with the light curing units was also measured. For all units, inhomogeneous distribution of light intensity across the guide tip was observed. Minimum light intensity values were 19-80% of the maximum values. In terms of surface hardness, inhomogeneous distribution was also observed for the materials irradiated with the tested units. Minimum values were 53-92% of the maximum values.
    Our results indicated that markedly inhomogeneous light emitted from light curing unit could result in inhomogeneous polymerization in some areas of the restoration below the light guide tip.
  • Takuma TSUGE, Yoshiyuki HAGIWARA, Hideo MATSUMURA
    2008 年 27 巻 1 号 p. 29-34
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    To date, there is no evidence that internal anti-rotation configurations are better than external ones. As part of a study to clarify the features and advantages of internal anti-rotation configurations, the objective of the present investigation was to compare and evaluate the marginal fit and size of microgap at the implant-abutment interface for several external and internal anti-rotation configurations. To this end, three internal connection and two external hex connection implant-abutment assemblies were examined in this study. The implant-abutment interface (I-A interface) was evaluated using three geometrical factors: vertical and horizontal discrepancies and size of microgap. Marginal fit and microgap size were measured by a scanning laser microscope. The I-A interface was also observed using a scanning electron microscope. Mean vertical discrepancy ranged from 22.6 to 62.2 μm, while horizontal discrepancy ranged from —27.1 to 16.0 μm. The microgap values of all I-A interfaces assessed in this study ranged from 2.3 to 5.6 μm. In conclusion, SEM images of I-A interface suggested no relationship between the geometrical factors and the type of anti-rotation configuration.
  • Kiyomi FUCHIGAMI, Kunio IKEMURA, Kensuke ICHIZAWA
    2008 年 27 巻 1 号 p. 35-48
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    The behavior of microencapsulated polymerization initiators in dental adhesives is unknown. This study investigated the effects of new microencapsulated initiators in novel, multi-purpose, PMMA-type adhesive resin on the bonding performance and polymerization reactivity. Microencapsulated BPO and 1,3,5-trimethylbarbituric acid (TMBA) with PEMA as a shell polymer were quantitatively synthesized at 97—98% yield with 30—54 μm diameter. Adhesive-MC (comprising the synthesized microcapsules) and Adhesive-BR (comprising bare BPO and bare TMBA) were prepared and stored at 5°C, 23°C, and 40°C for two months. MMA monomer was used as a solvent for the microcapsules. At the starting period, there were no significant differences between Adhesive-MC and Adhesive-BR in shear bond strength to enamel or dentin treated with or without surface treatment agent (p<0.05); moreover, their curing times (tc=304 seconds) were almost the same. After two months′ storage at 40°C, Adhesive-BR degraded in bond strength and showed markedly delayed polymerization reactivity as storage period progressed. In direct contrast, it was found that Adhesive-MC still retained its capabilities for adhesion to gold alloy and initiation of radical polymerization (p<0.05).
  • Kazuhiko OKAMOTO, Teruo INO, Naoki IWASE, Eitaroh SHIMIZU, Megumi SUZU ...
    2008 年 27 巻 1 号 p. 49-55
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    Using three-dimensional finite element analysis (3D-FEA), stress distributions in the remaining radicular tooth structure were investigated under the condition of varying diameters of fiber post for fiber post-reinforced composite resin cores (fiber post and core) in maxillary central incisors.
    Four 3D-FEA models were constructed: (1) fiber post (φ1.2, φ1.4, and φ1.6 mm) and composite resin core; and (2) gold-cast post and core.
    Maximum stresses in the tooth structure for fiber post and core were higher than that for gold-cast post and core. In the former models, stresses in the tooth structure as well as in the composite resin were slightly reduced with increase in fiber post diameter.
    These results thus suggested that to reduce stress in the remaining radicular tooth with a large coronal defect, it is recommended to accompany a composite resin core with a fiber post of a large diameter.
  • Takaya ISHII, Hiroyasu KOIZUMI, Takayuki YONEYAMA, Naomi TANOUE, Yumi ...
    2008 年 27 巻 1 号 p. 56-60
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    This study aimed to evaluate the bonding behaviors of a gold alloy and a titanium-aluminum-niobium (Ti-6Al-7Nb) alloy after priming with three metal conditioners. Cast alloy disks were ground and divided into the following four conditions: (1) unprimed control versus priming with (2) Alloy Primer, (3) Estenia Opaque Primer, or (4) V-Primer. The disks were bonded with tri-n-butylborane (TBB) initiated methacrylic resin, and shear bond strengths were determined both before and after 20,000 times of thermocycling. Alloy Primer and V-Primer—which contained a vinyl-thione monomer—were effective for bonding the Au-Pt-Pd alloy. As for the hydrophobic phosphate monomer contained in Alloy Primer and Estenia Opaque Primer, it was effective for bonding the Ti-6Al-7Nb alloy. Further, when specimens were primed with Alloy Primer that contained both functional monomers, bond strength to Ti-6Al-7Nb alloy was greater than that to Au-Pt-Pd alloy.
  • Suha TURKASLAN, Arzu TEZVERGIL-MUTLUAY, Bora BAGIS, Akikazu SHINYA, Pe ...
    2008 年 27 巻 1 号 p. 61-68
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    This study evaluated the fracture load and failure mode of various veneer materials cemented with or without the addition of a fiber-reinforced composite (FRC) layer at the adhesive interface. Sixty intact incisors were randomly divided into three groups. Group 1 was fabricated with the heat-press technique (IPS Empress 2); Group 2 with the copy milling technique (ZirkonZahn); and Group 3 with the direct or indirect composite technique (Z250)—and specimens were cemented either with or without FRC at the adhesive interface. The specimens were thermocycled and tested with a universal testing machine. No significant differences in fracture load (p>0.05) were found among the various veneer materials. The addition of FRC at the adhesive layer did not lead to significant differences in the fracture load (p>0.05) but resulted in differences in the failure mode. Laminate veneers made of composite, zirconia, and Empress 2 showed comparable mean fracture loads. However, the use of FRC at the interface changed their failure modes.
  • Yohsuke TAIRA, Kohji KAMADA, Mitsuru ATSUTA
    2008 年 27 巻 1 号 p. 69-74
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    The purpose of the present study was to evaluate the effects of four experimental primers on bond strength between a self-curing luting agent and silver-palladium-gold alloy. The experimental primers were in mixed solutions of a thiouracil primer (Metaltite) and a phosphate primer (Epricord, PM, PE, or PP), which were designated as Metaltite/Epricord, Metaltite/PM, Metaltite/PE, and Metaltite/PP respectively. Three primers (Metal Primer II, V-Primer, and Alloy Primer) were also prepared as controls. Alumina-blasted metal alloys were bonded with acrylic rods. After 5,000 thermocycles, the maximum shear bond strength was obtained with Metaltite/PE (27.8±2.4 MPa) and Metaltite/Epricord (27.6±5.9 MPa), followed by Metaltite/PP, Alloy Primer, Metaltite, Metaltite/PM, Metal Primer II, V-Primer, and Epricord. PE, PM, and PP showed the lowest bond strength. Results of this study revealed that the combined use of a thiouracil monomer and a phosphate monomer improved adhesive bonding. In this light, clinicians should pay attention to the types of functional monomers dissolved in a primer when fabricating resin-bonded prostheses.
  • Naoyuki IIZUKA, Shoji TAKENAKA, Yoshimi SHIGETANI, Takashi OKIJI
    2008 年 27 巻 1 号 p. 75-80
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    Removal of resin-based root canal filling materials may cause serious problems during root canal retreatment. This study compared the working time and amount of canal enlargement when different resin-based root canal filling materials were removed with K3 rotary instruments with or without heat-softening using System B. Root canal sealer/filling point combinations tested were Epiphany/Resilon, SuperBond/Resilon, SuperBond/gutta-percha, and Canals N/gutta-percha. The materials were filled into simulated curved resin canals and removed with K3 instruments in a standardized crown-down procedure. In terms of working time, Epiphany/Resilon required a significantly longer working time than the others. However, heat application with System B significantly reduced the working time for the removal of Epiphany/Resilon. In terms of canal enlargement, there were no significant differences among the tested groups as determined with digital morpho-metry. It was thus concluded that Epiphany removal with K3 rotary instruments might result in extended working time, but which could be reduced with heat-softening using System B.
  • Harumi SAKAMOTO, Yohei HIROHASHI, Haruka SAITO, Hisashi DOI, Yusuke TS ...
    2008 年 27 巻 1 号 p. 81-92
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    The objective of this study was to investigate the effect of active hydroxyl groups on a titanium (Ti) surface on the bond strength between Ti and segmented polyurethane (SPU) composite through γ-mercapto propyl trimethoxysilane (γ-MPS). Active hydroxyl groups on Ti surface oxide were controlled by immersion in hydrogen peroxide (H2O2) with different lengths of immersion time, and the resulting concentrations of active hydroxyl groups were evaluated using a zinc-complex substitution technique. For the H2O2-treated Ti, it was characterized using X-ray photoelectron spectroscopy and scanning electron spectroscopy. For the bond strength of Ti/γ-MPS/SPU interface, it was determined using a shear bond test. Results showed that the bond strength increased with increase in the concentration of active hydroxyl groups. In terms of durability after immersion in water at 310 K for 30 days, it was found that bond strength was improved with increase in active hydroxyl groups. Based on the results obtained, active hydroxyl groups on the surface oxide film were clearly one of the causes governing the interfacial bond strength.
  • Masanori ADACHI, Nobukazu WAKAMATSU, Yutaka DOI
    2008 年 27 巻 1 号 p. 93-98
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    To produce carbonate apatite (CAP) ceramics with the desired complex shapes using superplastic deformation, deformation behavior of CAP ceramics under constant loading as well as physical properties after deformation were evaluated. Sintered CAP ceramics were plastically deformed in an electric furnace attached to a universal hydraulic testing machine under a constant load. CAP ceramics subjected to an initial compressive pressure of 10 MPa showed an appreciable amount of plastic deformation at temperatures ranging from 720 to 800°C. Plastic deformation increased with increasing temperature from about 10% to 70% after two hours of loading. X-ray diffraction analysis and SEM observation further revealed that some CAP crystals were elongated and aligned with the c-axis normal to the loading direction during superplastic deformation. It was thus concluded that a marked plastic deformation of about 70% at 800°C would be sufficient for near-net-shape production of bioresorbable CAP bone substitutes with complex shapes.
  • Mutlu ÖZCAN, Henk NIJHUIS, Luiz Felipe VALANDRO
    2008 年 27 巻 1 号 p. 99-104
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    This study evaluated the effect of chairside and laboratory types of surface conditioning methods on the adhesion of dual-cure resin cement with MDP functional monomer to zirconia ceramic after thermocycling. Disk-shaped (diameter: 10 mm, thickness: 2 mm) Y-TZP ceramics (Lava, 3M ESPE) were used (N=40) and finished with wet 1200-grit silicon carbide abrasive paper. Specimens were randomly divided into four experimental groups according to the following surface conditioning methods (n=10 per group): Group 1—Chairside airborne particle abrasion with 50-μm Al2O3 + Alloy Primer (Kuraray); Group 2—Airborne particle abrasion with 50-μm Al2O3 + Cesead II Opaque Primer (Kuraray); Group 3—Airborne particle abrasion with 50-μm Al2O3 + Silano-Pen + silane coupling agent (Bredent); Group 4—Laboratory tribochemical silica coating (110-μm Al2O3 + 110-μm SiOx) (Rocatec) + silane coupling agent (ESPE-Sil). Adhesive cement, Panavia F 2.0 (Kuraray), was bonded incrementally to the ceramic surfaces using polyethylene molds (diameter: 3.6 mm, height: 5 mm). All specimens were thermocycled (5 and 55°C, 6,000 cycles) and subjected to shear bond strength test (1 mm/min). Data were statistically analyzed (one-way ANOVA, α=0.05), whereby no significant differences were found among the four groups (8.43±1.3, 8.98±3.6, 12.02±6.7, and 8.23±3.8 MPa) (p=0.1357). Therefore, the performance of chairside conditioning methods used for zirconia was on par with the laboratory alternative tested.
  • Ihsan HUBBEZOGLU, Barìs AKAOGLU, Arife DOGAN, Selda KESKIN, Gir ...
    2008 年 27 巻 1 号 p. 105-116
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    This study investigated the effects of three bleaching agents (Whiteness Perfect, Whiteness Super, and Whiteness HP) on the color change and refractive index of three dental composites (Admira, Durafill VS, and Gradia Direct). Twenty disk-shaped specimens (10×2 mm) of each composite were prepared and divided into four subgroups (n=5). An unbleached group was used as a control, while the remaining specimens in the three subgroups were bleached with one of the bleaching agents respectively. Color change was assessed according to CIELAB color system and refractive indices were determined by phase modulated spectroscopic ellipsometry. Color differences between bleaching and baseline value (ΔE) were less than 3.3 for all groups. However, bleaching with Whiteness HP led to noticeable color changes for Admira and Durafill VS. While this agent had no effect on the refractive indices of these composites, the other two agents containing carbamide peroxide increased their refractive indices. Therefore, results suggested that replacement of such composite restorations may be required after bleaching.
  • Tatsumi NOGUCHI, Shinji TAKEMOTO, Masayuki HATTORI, Masao YOSHINARI, E ...
    2008 年 27 巻 1 号 p. 117-123
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    This study compared differences in discoloration and dissolution in several titanium alloys with immersion in peroxide- or fluoride-containing solution. Commercially pure titanium (CP-Ti) and six titanium-based alloys were used: Ti-0.15Pd, Ti-6Al-4V, Ti-7Nb-6Al, Ti-55Ni, Ti-10Cu, and Ti-20Cr. Two test solutions were prepared for immersion of polished titanium and titanium alloys: one consisting of 0.2% NaF + 0.9% NaCl (pH 3.8 with lactic acid) and the other of 0.1 mol/l H2O2 + 0.9% NaCl (pH 5.5). Following immersion, color changes were determined with a color meter and released elements were measured using ICP-OES. Discoloration and dissolution rates differed between the two solutions. In the hydrogen peroxide-containing solution, color difference was higher in Ti-55Ni and Ti-6Al-4V than in any of the other alloys, and that Ti-55Ni showed the highest degree of dissolution. In the acidulated fluoride-containing solution, CP-Ti, Ti-0.15Pd, Ti-6Al-4V, Ti-7Nb-6Al, and Ti-10Cu alloys showed remarkable discoloration and dissolution with immersion. On the contrary, Ti-20Cr alloy showed very little discoloration and dissolution in either solution.
  • Harumi SAKAMOTO, Yohei HIROHASHI, Hisashi DOI, Yusuke TSUTSUMI, Yoshia ...
    2008 年 27 巻 1 号 p. 124-132
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    The objective of this study was to investigate the effect of UV irradiation on shear bond strength between a titanium (Ti) and a segmented polyurethane (SPU) composite through γ-mercapto propyl trimethoxysilane (γ-MPS). To this end, the shear bond strength of Ti/SPU interface of Ti-SPU composite under varying conditions of ultraviolet ray (UV) irradiation was evaluated by a shear bond test. The glass transition temperatures of SPU with and without UV irradiation were also determined using differential scanning calorimetry. It was found that the shear bond strength of Ti/SPU interface increased with UV irradiation. However, excessive UV irradiation decreased the shear bond strength of Ti/SPU interface. Glass transition temperature was found to increase during 40—60 seconds of UV irradiation. In terms of durability after immersion in water at 37°C for 30 days, shear bond strength was found to improve with UV irradiation. In conclusion, UV irradiation to a Ti-SPU composite was clearly one of the means to improve the shear bond strength of Ti/SPU interface.
  • Yong Hoon KWON, Chang-Min JANG, Jae-Hyeok JANG, Joo-Hee PARK, Tae-Hyon ...
    2008 年 27 巻 1 号 p. 133-138
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    The present study investigated the effect of fluoride released from dental restoratives on orthodontic NiTi wires. Five different restoratives (four fluoride-containing and one non-fluoride-containing) and four different NiTi wires were examined in this study. The pH of artificial saliva (AS) was adjusted to 2.5 and 6. Content of released fluoride was determined daily for 10 days. The morphology of wires was observed using a scanning electron microscope. After immersion for 10 days, the initial microhardness of the wires decreased by 0.3—5.6% depending on the test solution. Dyract AP (DA) and F2000 (F2) (compomers) released significantly more fluoride than the other resin products (composite resins) regardless of the test solution. In pH 2.5 solution, both DA and F2 released 40—45 ppm/day fluoride for five to six days. As for the wires in contact, they did not show any visible modification in surface morphology. Therefore, despite the released fluoride, wires in contact with the fluoride-containing restoratives were not damaged regardless of the pH value of test solution.
Technical reports
  • Temel KOKSAL, Idil DIKBAS
    2008 年 27 巻 1 号 p. 139-144
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    The purpose of this in vitro study was to evaluate the color stability of two brands of porcelain teeth and three brands of acrylic denture teeth. Samples were immersed into three staining drinks as test groups and distilled water as a control. Color measurements of teeth were performed by using a spectrophotometer. Before immersion, the initial color value of each tooth was recorded. Color change values were determined after 1 day, 1 week, 2 weeks, and 4 weeks of immersion. Color differences were characterized using the CIE L*a*b* color space. The color stability of all teeth was significantly affected by the immersion period (p<0.0001). Instant coffee was found to be the most chromogenic agent among the solutions tested (p<0.0001). Among the materials tested, porcelain was found to be more resistant to discoloration. It was concluded that acrylic teeth showed a higher degree of color change and that the amount of color change for each group increased proportionally with time.
  • Satoshi IMAZATO, Kaoru OHMORI, Roy RB RUSSELL, John F McCABE, Yasuko M ...
    2008 年 27 巻 1 号 p. 145-148
    発行日: 2008年
    公開日: 2009/03/05
    ジャーナル フリー
    In this study, the bactericidal activity of antibacterial monomer MDPB (12-methacryloyloxydodecylpyridinium bromide) against Streptococcus mutans was tested by a rapid method for monitoring viability. To S. mutans culture containing fluorescence staining solution that distinguishes live from dead cells, MDPB was added at a concentration of 250, 100, 50, or 10 μg/ml. Bacterial cells were observed by fluorescence microscopy and the percentage of dead cells was calculated. After 10, 20, or 30 minutes′ contact with MDPB, the live/dead ratio was measured by fluorometry and viable counts (CFU) determined by the conventional plating method.
    Viability staining revealed that MDPB exhibited significant bactericidal effects at 50 μg/ml or greater (ANOVA, Fisher's PLSD test), and complete killing of the cells at 250 μg/ml of MDPB was demonstrated in conjunction with a plating method. The staining method thus provided a sensitive means to determine loss of viability, and indicated the strong killing effects of MDPB on S. mutans.
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