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Yoshiko KAWAKAMI, Fumio TAKESHIGE, Mikako HAYASHI, Shigeyuki EBISU
2007 Volume 26 Issue 1 Pages
1-6
Published: 2007
Released on J-STAGE: February 06, 2009
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The purpose of this study was to investigate the interaction between mechanical and chemical fatigue in resin composites and dental ceramics, and the effects thereof on fatigue resistance of tooth-colored restoratives. To this end, the fatigue fracture resistance of restoratives under dry and aqueous conditions were analyzed by a dynamic fatigue crack propagation test using beam-shaped specimens with a precrack. Fatigue crack propagation characteristics were expressed by the correlation between fatigue crack growth rate (da/dN) and stress intensity factor range (ΔK). In addition, fatigue crack growth threshold (ΔK
th) was calculated. Following the fatigue test, a fractographic examination was performed using scanning electron microscopy. Fatigue crack initiation was retarded in resin composites under aqueous condition, but dental ceramics were susceptible to slow crack growth after crack initiation. SEM images of the fatigue facture surfaces reflected inorganic and organic filler particles of different sizes in composites and the bonding at crystal-glass interface in ceramics. It was concluded that water exerted different effects on the fatigue resistance of composites and ceramics.
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Shogo WAKAMATSU, Takuji IKEMI
2007 Volume 26 Issue 1 Pages
7-13
Published: 2007
Released on J-STAGE: February 06, 2009
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The aim of this study was to enhance the bond strength of one-step bonding agents to dentin. In particular, the focus was on using Catabrush™, the applicator system of AQ Bond Plus™. Catabrush was supplemented with N-phenylglycine and aromatic sulfinate as polymerization accelerators, as N-phenylglycine was reportedly beneficial in improving the bond strength to dentin. The results indicated that the bond strength to dentin was significantly augmented and the photo-polymerization as well as the chemical polymerization were both improved even in the moistened dentin when 1.0 wt% N-phenylglycine was added to AQ Bond Plus agent, hence implying significantly higher bond strength to dentin. It was therefore concluded that N-phenylglycine is useful as a polymerization accelerator to be adopted in the applicator system for one-step bonding agents.
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Hiroyasu KUROKAWA, Masashi MIYAZAKI, Toshiki TAKAMIZAWA, Akitomo RIKUT ...
2007 Volume 26 Issue 1 Pages
14-20
Published: 2007
Released on J-STAGE: February 06, 2009
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This study evaluated the clinical performance of five single-step self-etch adhesive systems over a one-year follow-up period in 98 restorations. Independent evaluations were performed at baseline (one week), after three months, six months, and one year, by two trained examiners using the modified US Public Health Service rating criteria. Color match, marginal integrity, anatomical form, surface roughness, marginal or interfacial staining, postoperative sensitivity, and secondary caries were evaluated. Results were analyzed using the Kruskal-Wallis test at a significance level of p<0.05. After one year, the restorations were re-evaluated and 100% retention rate was recorded. No caries were detected in association with any of the restorations. Marginal adaptation was the only measure that showed a slight deterioration over time, and there were no significant differences in this factor among the adhesive systems tested (p=0.464).
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María del Mar PÉREZ, Arafa SALEH, Ana YEBRA, Rosa PULGAR
2007 Volume 26 Issue 1 Pages
21-28
Published: 2007
Released on J-STAGE: February 06, 2009
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This study sought to assess the significance of the corrections introduced in the new CIEDE2000 color difference formula with respect to ΔE
*ab. The purpose of which was to provide sounder knowledge, and hence more informed decision-making, about applying this new formula to dental resin composites. With two different hybrid composites, color differences were calculated between unpolymerized and polymerized resin composites, between polymerized resin composites of different thicknesses (1 and 2 mm), and between polymerized resin composites cured with halogen and LED light curing units (LCUs). The two formulas differed significantly, with V
AB (E) (equal size) values higher than the inter-observer variability (V
AB (E)=11%) and V
AB (O) (original size) values greater than 25% for each of the data sets analyzed. Results obtained in this study agreed with and thus supported the recent recommendation of the Commission Internationale de l'Éclairage (CIE), whereby the new CIEDE2000 formula should be used to evaluate color differences of resin composites.
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Yoshinori KADOMA, Katsunori KOJIMA, Yoh TAMAKI, Yoshiaki NOMURA
2007 Volume 26 Issue 1 Pages
29-37
Published: 2007
Released on J-STAGE: February 06, 2009
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Adhesion promoting monomers for precious metals, 2,3-epithiopropyl methacrylate (EP1MA), 4,5-epithiopentyl methacrylate (EP3MA), 9,10-epithiodecyl methacrylate (EP8MA), 10,11-epithioundecyl methacrylate (EP9MA), 9,10-epithiodecyl 4-vinylbenzoate (EP8VB), 2,3-epithiocyclohexyl methacrylate (EPCHMA), and 3,4-epithiobutyl 2,2-bis(methacryloyloxymethyl)-propionate (EP2BMA), were used as surface treatment agents for pure gold to improve the durability of resin bonds against water. Treated specimens were butt-jointed together with MMA-PMMA resins, and tensile bond strength was measured after 2,000 thermal cycles in water. Bond strength to precious metal alloys was also determined under the same condition to clarify the influence of metal composition.
The adhesion performance of thiirane monomers to pure gold highly depended on their chemical structure. EP3MA, EP8MA, EP9MA, EP8VB, and EP2BMA showed excellent performance, while EP1MA exhibited a moderate one and EPCHMA a poor one. The comparison of pure gold with precious metal alloys revealed the usefulness of pure gold as a standard, common adherend for bond strength evaluations.
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Hiroyuki ARIKAWA, Takahito KANIE, Koichi FUJII, Hideo TAKAHASHI, Seiji ...
2007 Volume 26 Issue 1 Pages
38-44
Published: 2007
Released on J-STAGE: February 06, 2009
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The purpose of this investigation was to examine the effect of filler particle size and shape as well as filler content on light transmittance characteristics and color of experimental composite resins. A mixture of 30 mol% Bis-GMA and 70 mol% TEGDMA was prepared as a base monomer and to which a photoinitiator (camphorquinone) and a co-initiator (N,N-dimethylaminoethyl methacrylate) were added. Four different irregular- and spherical-shaped filler types with an average particle size of 1.9-11.1 μm were added to the mixture in three different filler contents of 20, 30, and 40 vol%. Light transmittance characteristics including light diffusion characteristics of the materials were evaluated. Color values and color differences among filler contents of the materials were also determined. Materials containing smaller and irregular-shaped fillers showed higher light transmittance and diffusion angle distribution with a sharper peak, as compared with those containing larger and spherical-shape fillers. It was also found that there was a significant correlation between the specific surface area of fillers and the color difference of the materials containing the fillers.
Our results indicated that the shape of filler particles, as well as particle size and filler content, significantly affected the light transmittance characteristics—including light diffusion characteristics—and color of composite resins.
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Rogelio José SCOUGALL VILCHIS, Seigo YAMAMOTO, Noriyuki KITAI, ...
2007 Volume 26 Issue 1 Pages
45-51
Published: 2007
Released on J-STAGE: February 06, 2009
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This study evaluated the shear bond strength of stainless steel brackets bonded to enamel with a new fluoride-releasing orthodontic adhesive system. A total of 140 extracted human bicuspids were randomly divided into four groups. Group I (Transbond XT) was a control group in which enamel was etched with phosphoric acid. For the remaining groups, enamel was conditioned with a self-etching primer (SEP): Group II (Transbond Plus), Group III (BeautyOrtho Bond), and Group IV (BeautyOrtho Bond + Salivatect). Stainless steel brackets were bonded to all tooth samples. After which, the samples were stored, thermocycled, tested, and statistically analyzed. Besides bond strength evaluation, the adhesive remnant index (ARI) was also evaluated. The shear bond strengths of Groups II, III, and IV were significantly lower than Group I, and Group II was significantly greater than that of Group III. Concerning ARI scores, no significant differences were found between the groups. Further, no enamel fracture was observed during shear bond test with the new SEP.
In conclusion, when enamel was conditioned with the new SEP, the mean values of shear bond strength yielded were lower than when it was etched with 37% phosphoric acid. Nonetheless, these mean values were higher than the average suggested by Reynolds as optimum for clinical treatment.
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Bor-Shiunn LEE, Shu-Han KANG, Yin-Lin WANG, Feng-Huei LIN, Chun-Pin LI ...
2007 Volume 26 Issue 1 Pages
52-61
Published: 2007
Released on J-STAGE: February 06, 2009
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DP-bioglass paste has been demonstrated to produce 60 μm of sealing depth on exposed dentinal tubules. However, the occlusive effect depended on a continuous placement of DP-bioglass paste on dentinal surface for three days. In a bid to fabricate highly reactive DP-bioglass particles, a sol-gel method was used together with HNO
3, NaOH, and H
3PO
4 as catalysts. As a result, the application time of DP-bioglass paste was significantly reduced to 10 minutes. Percentage of tubular occlusion with DP-bioglass was 53.2-65.4%, while One Coat Bond and Seal & Protect yielded 51.3% and 41.2% respectively. Further, the average depth of tubular occlusion with DP-bioglass was 55.8-62.7 μm, while One Coat Bond and Seal & Protect produced 40.8 μm and 32.5 μm respectively. In conclusion, the best sealing performance of tubular occlusion was rendered by DP-bioglass catalyzed with HNO
3. Its performance was significantly better than Seal & Protect, and was considered to exhibit the greatest potential in treating dentin hypersensitivity.
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Nuran YANIKOGLU, Zeynep YESIL DUYMUS
2007 Volume 26 Issue 1 Pages
62-67
Published: 2007
Released on J-STAGE: February 06, 2009
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The aim of this study was to determine the solubility of dental cements in artificial saliva of different pH values. A total of 180 specimens—20 specimens (20 mm diameter×1.5 mm thickness) for each dental cement—were prepared. After the specimens were weighed, they were set in the media with different pH values. After 24 hours, 72 hours, seven days, and 28 days, the specimens were taken out, dried in a desiccator, and re-weighed. Percentage of solubility at each time period was calculated as 100 per cent times weight loss divided by the initial weight of the specimen.
Analysis of variance and LSD multiple comparison test were applied. It was found that cement type, storage time, and medium pH exerted statistically significant (p<0.001) effects on solubility. Among the tested cement types, zinc phosphate cement (Adhesor Carbofine) presented the highest solubility. In terms of medium pH, the cements seemed to be most stable in the medium with pH 7.
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Yun-Hoa JUNG, Jeong Kil PARK, Seok-Hee HYUN, Hyo-Joung SEOL, Hyung-Il ...
2007 Volume 26 Issue 1 Pages
68-77
Published: 2007
Released on J-STAGE: February 06, 2009
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The aim of this study was to evaluate the effect of acetic NaF solutions on fluoride-containing restorative materials. As the pH value of solution decreased, the degree of microhardness change in restorative materials increased—regardless of product. Dyract AP (DA) and F2000 (F2) (polyacid-modified resin composites) showed the greatest decrease in microhardness after immersion for three days. Similarly, as the pH value decreased, volumetric weight change (loss) increased in all products. DA and F2 showed the greatest—but similar—weight change in pH 3.5 solution among the products. In terms of color change, most specimens showed a slight color change after immersion for one and three days—regardless of pH value. However, F2 in pH 3.5 solution showed a noticeable color change (ΔE
*=2.1). In terms of surface morphology, specimens in distilled water showed only minor surface modification. However, in pH 3.5 solution, DA and F2 showed randomly propagating cracks, while Solitaire 2 and Tetric Ceram (resin composites) lost many fillers less than 2 μm in size.
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Takashi TSURUOKA, Yasuhiro NAMURA, Noriyoshi SHIMIZU
2007 Volume 26 Issue 1 Pages
78-83
Published: 2007
Released on J-STAGE: February 06, 2009
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We produced experimentally a new bonding material that consisted of a mixture of a base resin (4-META/MMA-TBB resin adhesive) and thermoexpandable microcapsules for safe, easy debonding. Microcapsules in the base resin would start expansion at 80°C, leading to a remarkable decrease in bond strength. Stainless steel brackets were bonded to bovine permanent mandibular incisors using bonding materials containing the microcapsules at different contents. After thermal cycling or heating, the shear bond strength of the brackets was measured. Shear bond strength of the bonding materials containing 30—40 wt% microcapsules decreased to about one-third or one-fifth that of the base resin on heating. Heating the brackets for eight seconds increased the temperature in the pulp chamber by 2°C, which should not induce pulp damage.
Results obtained suggested that the new bonding material should prove useful for removing brackets easily at the time of bracket debonding without any pain or enamel cracks, while maintaining the bonding strength during active orthodontic treatment.
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Yasuhiro TANAKA, Ikuya WATANABE, Toru OKABE
2007 Volume 26 Issue 1 Pages
84-88
Published: 2007
Released on J-STAGE: February 06, 2009
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This study investigated the interfacial microstructure between gold-coated titanium and low-fusing porcelain. The square surfaces of cast titanium split rods were sputter-coated with gold using a sputter coater at 40 mA for 1,000 seconds. Specimens were prepared for transmission electron microscopy (TEM) by cutting and polishing two pieces of the gold-coated split-rod specimens, which were glued and embedded in Cu tubes with an epoxy adhesive. TEM observation was also conducted for the gold-coated specimens after degassing and porcelain fusing. Due to the gold coating, intermetallic compounds of Au-Ti formed under the sputtered gold layer after degassing and porcelain fusing. Ti
3Au and Ti
3Al layers were also observed beneath the Au-Ti intermetallic compound layer. There was good adhesion of porcelain to the Au-Ti compound and Ti oxides without any gaps or formation of a Ti-deficient intermediate layer, which is normally observed at the titanium-porcelain interface. The results of this TEM study suggested that gold-sputter-coating the cast titanium surface produced a Ti-Au intermetallic compound and suppressed the formation of a Ti-deficient intermediate layer, resulting in improved adherence between porcelain and titanium.
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Toshio SATO, Hidekazu TAKAHASHI, Toshio HONGO, Iwao HAYAKAWA
2007 Volume 26 Issue 1 Pages
89-95
Published: 2007
Released on J-STAGE: February 06, 2009
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The purpose of this study was to evaluate the effect of degradation of a denture base resin on bond strength to relining resins. Denture base resin specimens were immersed under various conditions to simulate degradation. Tensile bond strength of denture base resin after immersion to relining resins was measured with or without surface grinding. The bond strength of denture base resin without grinding after immersion to relining resin was significantly lower than that before immersion. However, bond strength was improved by surface grinding before bonding. These results suggest that bonding efficiency of denture base resin to relining resins was affected by immersion condition, which caused potential degradation of the denture base resin.
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Zora VENCLÍKOVÁ, Oldrich BENADA, Jirina BÁRTOV&Aa ...
2007 Volume 26 Issue 1 Pages
96-104
Published: 2007
Released on J-STAGE: February 06, 2009
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The composition of metallic pigmentations in gingiva and dental roots was determined by means of transmission electron microscopy with energy dispersive x-ray microanalysis. The systemic immune response to the metals found in the oral cavity was evaluated in 10 patients by using a modified lymphocyte proliferation test. Immunological results were compared with a group of five controls without metallic materials and pigmentation. Dense particles of various shapes and sizes, as well as of diverse extracellular and intracellular localization patterns, were detected in the pigmented lamina propria gingivae. Metallic deposits consisted predominantly of silver accompanied by selenium or sulfur or both. Besides, Ag, Au, Cr, Ni, Fe, Hg, Cu, and Ti were identified in dentinal tubules of teeth reconstructed with dental alloys. Nine patients with metallic pigmentations had a positive lymphocyte proliferative response to one or more metals present in their own metal reconstructions. Results of this study thus indicated that dental alloys—by virtue of their corrosion process—might pose a significant risk to immunologically susceptible patients.
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Kunio IKEMURA, Franklin R. TAY, Norihiro NISHIYAMA, David H. PASHLEY, ...
2007 Volume 26 Issue 1 Pages
105-115
Published: 2007
Released on J-STAGE: February 06, 2009
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Multi-purpose bonding performance of three kinds of newly synthesized phosphonic acid monomers was investigated. Methacryloxyalkyl or acryloxyalkyl phosphonoacetates of 6-MHPA, 6-AHPA, 10-MDPA were synthesized in 42.8-51.9% yields with a light yellow viscous liquid, and identified as new compounds by
1H NMR, IR, and elemental analysis. Conventional adhesive monomers, namely VBPA, 4-META, and 4-AETA, and CEBA-
p-TSMo-
t-BPMA initiator were also used. Seven experimental composite-type adhesive resins comprising these six kinds of adhesive monomers and None (control) with the initiator were prepared. Tensile bond strengths of adhesive resins to unetched ground enamel and dentin, ground porcelain, and sandblasted Ni-Cr alloy were measured at a crosshead speed of 1.0 mm/min. Results showed that except with VBPA, there were no significant differences among 6-MHPA, 6-AHPA, 10-MDPA, 4-AETA, and 4-META in bonding performance to the adherends (p<0.01). It was found that the new phosphonic acid monomers provided good multi-purpose adhesion to all adherends tested.
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Gul TOSUN, Yagmur SENER, Abdulkadir SENGUN
2007 Volume 26 Issue 1 Pages
116-121
Published: 2007
Released on J-STAGE: February 06, 2009
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The aim of this study was to determine the effect of three storage solutions and two storage durations on microshear bond strength (μSBS) of a resin composite. Sixty non-carious human permanent molars were stored in three storage solutions (0.1% thymol, 10% formalin, and distilled water). Each tooth was separated mesio-distally into two parts. Specimens of the first part were stored for 24 hours, while specimens of the second part were stored for two months in the solutions. After each storage period, the enamel surface was covered with a composite resin in combination with an etch-rinse adhesive system. Specimens were then serially sectioned into sticks of 1 mm
2 bond area and subjected to μSBS test.
There were no statistically significant differences between the two storage periods for each solution (p>0.05). The thymol solution group showed lower μSBS values than those of distilled water for both storage periods (p<0.05). As for the formalin group, its μSBS values were not statistically different from those of distilled water and thymol groups at each storage period (p>0.05).
In conclusion, the thymol solution caused the μSBS of the resin composite to decrease when compared to both formalin and distilled water after 24 hours and two months. However, the μSBS of the resin composite was not affected by storage duration.
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Yasushi SHIMADA, Md Akhtar UZZAMAN, Junji TAGAMI, Toru TANAKA, Takashi ...
2007 Volume 26 Issue 1 Pages
122-128
Published: 2007
Released on J-STAGE: February 06, 2009
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To compare the pulpal responses to light-cured and self-cured resin cements, cervical cavities were prepared in monkey's teeth, followed by application of etching gel and adhesive (Single Bond). A dual-cure resin cement (RelyX™ ARC) was applied, and hybrid composite inlays (Estenia) were bonded to the cavities. In one group, the cavities were photoirradiated for 20 seconds and the resin cement light-cured. In the other group, the resin cement was self-cured for six minutes without any photoirradiation. After experimental periods of seven, 28, and 70 days, histological features of pulp tissue were evaluated and compared. Results showed no significant differences in the histological features of the pulp tissues between the two curing methods. Both light-cured and self-cured resin cements showed acceptable biological compatibility with the monkey pulp. No bacterial penetration along the cavity walls was detected with either curing method.
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Hiroko SOMA, Yukio MIYAGAWA
2007 Volume 26 Issue 1 Pages
129-134
Published: 2007
Released on J-STAGE: February 06, 2009
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Nine kinds of experimental soft magnetic resin composites containing SUS447J1 stainless steel particles as filler were prepared. A UDMA/MAA resin with an MAA mole fraction of 0.67 was used as a matrix resin. The effects of three levels of 4-META content and three levels of filler content on the setting and flexural properties were studied. Working time and setting time significantly increased with increase of 4-META and filler contents. Flexural strength significantly increased with increase of 4-META content but with decrease of filler content. Elastic modulus simply increased with increase of both 4-META and filler contents. Although the flexural strength obtained was low, results were considered promising being the first step of this novel development.
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Shuzo KITAYAMA, Toru NIKAIDO, Masaomi IKEDA, Richard M. FOXTON, Junji ...
2007 Volume 26 Issue 1 Pages
135-143
Published: 2007
Released on J-STAGE: February 06, 2009
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This study was conducted to examine the shear bond strengths of orthodontic brackets to ground enamel with two self-etching adhesives (Beauty Ortho Bond and Transbond XT) and two phosphoric acid-etching adhesives (Kurasper F and Orthomite Superbond). After the bonded specimens were stored in water at 37°C for 24 hours, they were subjected to thermal cycling (TC) at 0 and 5000 cycles. Then, shear bond test was performed at a crosshead speed of 1 mm/min. Results indicated that the self-etching adhesives did not significantly differ in bond strength before and after TC (p>0.05), while the phosphoric acid-etching adhesives showed a significant reduction after TC (p<0.05). The predominant modes of bracket failure for the self-etching adhesives were at the enamel-resin interface, leaving less than 50% of the adhesive on the enamel surface. It was concluded that the self-etching adhesives exhibited stable bond strength to ground enamel without causing decalcification nor damage to the enamel surface.
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