-
Masakazu HIRATA, Hiroyasu KOIZUMI, Naomi TANOUE, Tomohisa OGINO, Mahok ...
2011 Volume 30 Issue 2 Pages
127-135
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 10, 2011
JOURNAL
FREE ACCESS
The purpose of the current study was to evaluate the influence of light sources on the mechanical properties and wear characteristics of indirect composite materials. The two composite materials used were Estenia C&B and Epricord. The three laboratory polymerization units used, of which the wavelength range was 400–500 nm, were Hyper LII (two metal halide lamps of 4.82 mW/cm
2), α-Light II (one halogen lamp and two fluorescent tubes of 3.60 mW/cm
2), and Labolight LV-II (three fluorescent tubes of 0.63 mW/cm
2). Three-body wear test was performed using indirect composite plate specimens, a gold alloy antagonist, and a polymer slurry. Wear depths of Estenia C&B polymerized with Hyper LII, α-Light II, and Labolight LV-II were 5.7, 18.5, and 64.2 μm respectively, whereas those of Epricord were 12.9, 18.7, and 48.5 μm respectively. Results showed that, after 100,000 cycles of localized loading, high-intensity light sources were effective in enhancing the wear resistance of both composite materials.
View full abstract
-
Takeshi FUJITA, Takanobu SHIRAISHI, Yasuko TAKUMA, Kunihiro HISATSUNE
2011 Volume 30 Issue 2 Pages
136-142
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 10, 2011
JOURNAL
FREE ACCESS
The corrosion resistance of nine experimental Pd-free Ag-Au-Pt-Cu dental alloys in a 0.9% NaCl solution was investigated using cyclic voltammetry (CV), optical microscopy, and scanning electron microscopy (SEM). CV measurements revealed that the breakdown potential (
Ebd) and zero current potential (
Ezc) increased with increasing Au/(Au+Ag) atomic ratio. Thus, the Au/(Au+Ag) atomic ratio, but not the Cu content, influenced the corrosion resistance of Ag-Au-Pt-Cu alloys. After the forward scan of CV, both optical and scanning electron microscope images showed that in all the experimental alloys, the matrix phase was corroded but not the second phase. From corrosion resistance viewpoint, the Ag-Au-Pt-Cu alloys seemed to be suitable for clinical application.
View full abstract
-
Tomohiro KAWAGUCHI, Hiroshi SHIMIZU, Lippo V.J. LASSILA, Pekka K. VALL ...
2011 Volume 30 Issue 2 Pages
143-150
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 04, 2011
JOURNAL
FREE ACCESS
The aim of this study was to investigate the bond durability of heat-polymerized denture base resin to cast CP Ti and Co-Cr alloy. The alloy specimens were divided into five groups: 1) airborne-particle abraded with 50 μm alumina (SAND), 2) Rocatec tribochemical silica coating system (RO), 3) air-abraded followed by application of Epricord Opaque Primer (EP), 4) air-abraded followed by application of Super Bond C&B liquid (SB), 5) air-abraded followed by application of Alloy Primer (AL). Heat-polymerized denture resin was applied to the bonding area and polymerized according to the manufacturer’s instructions. The halves of all specimens were thermocycled up to 10,000 cycles. Before thermocycling SB and AL showed significantly higher shear bond strengths than SAND, RO, EP for both metals. The shear bond strength of AL group after thermocycling was significantly higher than that of the other groups.
View full abstract
-
Hiroyuki ARIKAWA, Hideo TAKAHASHI, Yoshito MINESAKI, Kouichi MURAGUCHI ...
2011 Volume 30 Issue 2 Pages
151-157
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 04, 2011
JOURNAL
FREE ACCESS
A method for improving the uniformity of the radiation light from dental light-curing units (LCUs), and the effect on the polymerization of light-activated composite resin are investigated. Quartz-tungsten halogen, plasma-arc, and light-emitting diode LCUs were used, and additional optical elements such as a mixing tube and diffusing screen were employed to reduce the inhomogeneity of the radiation light. The distribution of the light intensity from the light guide tip was measured across the guide tip, as well as the distribution of the surface hardness of the light-activated resin emitted with the LCUs. Although the additional optical elements caused 13.2–25.9% attenuation of the light intensity, the uniformity of the light intensity of the LCUs was significantly improved in the modified LCUs, and the uniformity of the surface hardness of the resin was also improved. Our results indicate that the addition of optical elements to the LCU may be a simple and effective method for reducing inhomogeneity in radiation light from the LCUs.
View full abstract
-
Thidarat ANGWARAWONG, Stephan T. DUBAS, Mansuang ARKSORNNUKIT, Prasit ...
2011 Volume 30 Issue 2 Pages
158-169
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 16, 2011
JOURNAL
FREE ACCESS
Polyelectrolyte multilayer (PEM) film can modify the surface properties of materials to improve cellular responses. In this study poly(diallyldimethylammonium chloride) (PDADMAC), poly(sodium 4-styrene sulfonate) (PSS) and poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (PSS-co-MA) were assembled into PEM {(PDADMAC/PSS)
4/PDADMAC+PSS-co-MA} film on glass surfaces and its ability on affecting osteoblast functions were examined. PSS-co-MA film showed an increase roughness and more wettable surface as compared to glass. When the osteoblast cell line, MC3T3-E1, was seeded on the surfaces, no differences were observed in cell attachment or spreading on either PSS-co-MA film or glass at 4-16 hours. However, increases in alkaline phosphatase activity (day-5 and 7) and the expression of osteocalcin mRNA/protein at day-13 were observed. Cells cultured on PSS-co-MA film developed a faster rate of calcium deposition at day-15 compared to control. In conclusion, PSS-co-MA film enhanced osteoblast differentiation and could be used to promote mineralization and improve osseointegration for dental implants.
View full abstract
-
Takahiro TANAKA, Koji HANAOKA, Masuji YAMAGUCHI, Toyohiko SHINDO, Karl ...
2011 Volume 30 Issue 2 Pages
170-175
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 10, 2011
JOURNAL
FREE ACCESS
The preceramic polymer perhydropolysilazane (PHPS) is an attractive candidate as a coating material to prevent discoloration of veneering resin composites. At the present time, however, a practical method to apply this material is not available. The purpose of this study was to establish a low-temperature method for applying a silica film coating to a veneering resin composite. Two types of PHPS, NP and NL, were coated onto a veneering resin composite. The specimens were exposed to hydrogen peroxide vapor at 97°C, and the state of the conversion process was evaluated using FT-IR. With exposure to the hydrogen peroxide vapor, a 0.5-μm-thick silica film similar to that produced by baking was formed on the surface of the NP samples in 10 min, while a 0.2-μm-thick film was formed on the NL in 15 min. The silica coating method described in this study may mitigate the discoloration of veneering resin composite.
View full abstract
-
Noriko MUTOH, Nobuyuki TANI-ISHII
2011 Volume 30 Issue 2 Pages
176-182
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 10, 2011
JOURNAL
FREE ACCESS
We aimed to establish an experimental animal model to evaluate materials for endodontic therapy. We focused on the biocompatibility of new paste-type zinc oxide-eugenol (ZOE) sealer. The results of this sealer were compared with those of conventional powder/liquid ZOE and eugenol-free sealers. The molars of Wistar rats were extracted and repositioned in the original socket after application of the sealers on the root apices. Mild inflammation occurred in the periapical tissue of the replanted teeth with both ZOE sealers on day 7, whereas the eugenol-free sealer induced severe inflammation. On day 14, the lesions induced by all types of sealers were healed and replaced predominantly by fibrous connective tissue. Thus, all endodontic materials showed high biocompatibility, although the extent of inflammatory reactions during the early stages varied depending on the types of materials. We demonstrated that our animal model was useful for the assessment of the biocompatibility of endodontic materials.
View full abstract
-
Luca RAMAGLIA, Loredana POSTIGLIONE, Gaetano DI SPIGNA, Gabriele CAPEC ...
2011 Volume 30 Issue 2 Pages
183-192
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 12, 2011
JOURNAL
FREE ACCESS
Osseointegrated dental implants have been successfully used over the past several years, allowing functional replacement of missing teeth. Surface properties of titanium dental implants influence bone cell response. Implant topography appears to modulate cell growth and differentiation of osteoblasts thus affecting the bone healing process. Optimal roughness and superficial morphology are still controversial and need to be clearly defined. In the present study we evaluated
in vitro the biological behavior of SaOS-2 cells, a human osteoblast-like cell line, cultured on two different titanium surfaces, smooth and sandblasted-acid-etched, by investigating cell morphology, adhesion, proliferation, expression of some bone differentiation markers and extracellular matrix components. Results showed that the surface topography may influence
in vitro the phenotypical expression of human osteoblast-like cells. In particular the tested sandblasted-acid-etched titanium surface induced a significantly increased Co I deposition and α2-
β1 receptor expression as compared to the relatively smooth surface, promoting a probable tendency of SaOS-2 cells to shift toward a mature osteoblastic phenotype. It is therefore likely that specific surface properties of sandblasted-acid-etched titanium implants may modulate the biological behavior of osteoblasts during bone tissue healing.
View full abstract
-
Yuko ITO, Yasuko MOMOI
2011 Volume 30 Issue 2 Pages
193-198
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 12, 2011
JOURNAL
FREE ACCESS
This study investigated the bleaching efficacy of a mixture of sodium hydrogen carbonate (NaHCO
3) and 30% hydrogen peroxide (H
2O
2), the latter being an active ingredient in in-office bleaching products. A commercially available 35% H
2O
2-based in-office bleaching product was used as a control and for comparison. Enamel surfaces after bleaching were evaluated for post-bleaching color change, Vickers hardness, surface roughness, erosion depth, and surface morphology (SEM images). The bleaching efficacy of 30%H
2O
2-NaHCO
3 was comparable to that of control, and favorable results over the control were obtained after bleaching with 30%H
2O
2-NaHCO
3, lower increase in surface roughness, smaller erosion depth, and reduced extent of enamel erosion based on SEM images. These results were obtained because an addition of NaHCO
3 to H
2O
2 changed the initially low pH to a higher one.
View full abstract
-
Koichi MURAGUCHI, Hiroyuki MINAMI, Yoshito MINESAKI, Shiro SUZUKI, Tak ...
2011 Volume 30 Issue 2 Pages
199-205
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 12, 2011
JOURNAL
FREE ACCESS
This study investigated the efficacies of adhesive resin cements (Clearfil SA Luting, Maxcem, G-CEM, RelyX Unicem Clicker, Vitremer Paste) for bonding to Ag-Pd-Cu-Au alloy not surface-pretreated with metal primer. For control, Panavia F 2.0 —developed for use with a proprietary metal primer, Alloy Primer— was tested with and without metal primer application. Pairs of alloy disks (10.0 and 8.0 mm in diameters, 3.0 mm thickness) were air-abraded with alumina and bonded with one of the cements. Shear bond strengths (SBSs) were measured before and after 50,000 times of thermocycling. Among Maxcem, RelyX Unicem Clicker and the control, there were no statistical differences in SBS before and after thermocycling. After thermocycling, Clearfil SA Luting exhibited the highest SBS among all the cements. Results showed that Clearfil SA Luting, Maxcem, and RelyX Unicem Clicker were efficacious for bonding to Ag-Pd-Cu-Au alloy after air abrasion surface treatment for the latter.
View full abstract
-
Yukie TAMURA, Keishi TSUBOTA, Eiichiro OTSUKA, Hajime ENDO, Chikako TA ...
2011 Volume 30 Issue 2 Pages
206-211
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 04, 2011
JOURNAL
FREE ACCESS
This study investigated the influence of the bonded surface area and the crosshead speed on the dentin bond strengths of self-etch adhesives. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were wet ground with #600 silicon carbide (SiC) paper. The dentin surfaces were treated according to the manufacturer’s instructions. Adhesives were applied, and the resin composites were condensed into molds (2.4 or 4.0 mm in internal diameter), placed on to the dentin, and then light activated. Ten samples per test group were shear tested at crosshead speeds of 0.1, 0.5, 1.0, 5.0, and 10.0 mm/min. The results showed that higher crosshead speeds were associated with higher dentin bond strengths. This relationship was more significant for specimens with a smaller dentin bonding surface area.
View full abstract
-
Tomotaro NIHEI, Shigeaki KURATA, Katsura OHASHI, Kozo UMEMOTO, Toshio ...
2011 Volume 30 Issue 2 Pages
212-215
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 16, 2011
JOURNAL
FREE ACCESS
The aims of this study were to evaluate a new restorative method using a carbon dioxide laser (CO
2-laser) and to evaluate the acid resistance of teeth. Experimental calcium phosphate glass (CPG) powder and two low melting point ceramics (Finesse and zirconium silicate) were fused to enamel surfaces using a CO
2-laser at an irradiation intensity of 1.0 watt for 30 seconds with a beam size of 0.49 mm at the focal point. The treated teeth were observed with a scanning electron microscope, and the acid resistance of the treated enamel surfaces was evaluated. The CPG fused successfully to the enamel surface, and the treated enamel surface showed high acid resistance compared with the low melting point ceramics and the non-irradiated surfaces. This system may lead to the development of new restorative methods that do not require the use of bonding agents.
View full abstract
-
Luigi CIANCONI, Gabriele CONTE, Manuele MANCINI
2011 Volume 30 Issue 2 Pages
216-221
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 04, 2011
JOURNAL
FREE ACCESS
This study evaluated the shear bond strength, failure modes, and confocal microscopy of two different amalgam alloy restorations lined with five adhesive systems. Two regular-set high-copper dental amalgam alloys, Amalcap Plus and Valiant Ph.D, and five commercially available adhesive systems were selected. One hundred and twenty freshly-extracted human third molars were used for the study. The results were statistically evaluated using two-factor analysis of variance (ANOVA). The shear bond strength (SBS) of amalgam to dentin was significantly affected by both the adhesive (
p<0.0001) and amalgam alloy (
p<0.0002). Regarding mode of failure (MF), among samples restored with Valiant Ph.D, 31 of 50 exhibited adhesive failure, and 19 displayed mixed failure. Laser optical microscopy (OM) of the bonded interface revealed the presence of a good hybrid layer was evident in all experimental groups. Higher bond strengths were measured for four of the five adhesives when used in combination with the spherical alloy.
View full abstract
-
Popi PROTOPAPA, Eleana KONTONASAKI, Dimitrios BIKIARIS, Konstantinos M ...
2011 Volume 30 Issue 2 Pages
222-231
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 04, 2011
JOURNAL
FREE ACCESS
The aim of this study was to investigate the possible reinforcement of Nanodiamonds (ND) in a PMMA resin for fixed interim restorations. The fracture toughness (K
Ic), impact strength and the dynamic thermomechanical properties (T
g, E´, E´´, tanδ) of a series of PMMA-ND nanocomposites with different amounts of ND were evaluated. The fracture toughness increased as the ND percentage increased up to 0.38% wt but a greater amount of ND induced a decrease in K
Ic. Impact strength and Young’s modulus were also increased by increasing nanoparticles content, indicating the reinforcing effect of ND. Dynamic mechanical properties were also affected. By increasing the ND content an increase of storage modulus was recorded, while glass transition was shifted at higher temperatures. Under the limitations of this study, it can be suggested that reinforcing PMMA with ND nanoparticles —especially at low concentrations— may increase the overall performance of fixed interim prostheses.
View full abstract
-
Takashi WAKITA, Jin NAKAMURA, Yoshio OTA, Akiko OBATA, Toshihiro KASUG ...
2011 Volume 30 Issue 2 Pages
232-238
Published: 2011
Released on J-STAGE: April 08, 2011
Advance online publication: March 10, 2011
JOURNAL
FREE ACCESS
Two types of nonwoven fabric, consisting of siloxane-doped vaterite (SiV) and poly(lactic acid) (PLA), for guided bone regeneration (GBR) were prepared by an electrospinning. One of the fabrics, SiV-PLA(M), was derived from PLA mixed with the solution of SiV dispersed in chloroform. Another one, SiV-PLA(K), was derived from a composite prepared by kneading SiV and PLA while heating at 200°C. The SiV-PLA(K) fabric shows higher degradability in dilute NaOH
aq. than the SiV-PLA(M) fabric. To improve the cellular compatibility of the fabric, the fibers were coated with hydroxyapatite (HA) by soaking in simulated body fluid. The HA-coated SiV-PLA(K) fabric showed the release of silicate ions; the amount was reduced by 1/5 to 1/8 compared with that of the HA-coated SiV-PLA(M) fabric, and the excessive release was controlled. The preparation route of kneading at 200°C led to formation of a fabric with degradation behavior and ion releasability effective for bone regeneration.
View full abstract
