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Somsak SIRIRUNGROJYING, Tohru HAYAKAWA, Kayo SAITO, Daijiro MEGURO, Ki ...
2004 年 23 巻 3 号 p.
251-257
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to determine the bonding durability when a Megabond self-etching primer is used with 4-META/MMA-TBB resin to bond metal orthodontic brackets to human premolar enamel. Three conditions of enamel were prepared: Megabond self-etching primer without saliva contamination, Megabond self-etching primer with saliva contamination, and repeat Megabond self-etching priming after saliva contamination. Shear bond strengths were measured after immersion in water at 37°C for 24 hours, or after 2000 or 5000 cycles of thermal cycling between 5°C and 55°C. There were no significant differences in shear bond strength among the three groups not only before thermal cycling, but also after thermal cycling. FE-SEM observation revealed the presence of saliva and reduced amount of resin tag formation after saliva contamination.
The present study provided the evidence in human teeth that when using 4-META/MMA-TBB resin, Megabond self-etching primer treatment produced tight bonding even when surface was contaminated with saliva.
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Yilinuer TIELIEWUHAN, Isao HIRATA, Akiko SASAKI, Hideyuki MINAGI, Masa ...
2004 年 23 巻 3 号 p.
258-264
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
To develop a new biodegradable scaffold biomaterial reinforced with a frame, synthesized CO
3apatite (CO
3Ap) was mixed with a neutralized collagen gel. Then, 0 and 70% (w/w) CO
3Ap-collagen mixtures (70% CO
3Ap weight/mixture weight) were lyophilized into sponges in a HAp frame ring with 0.5-mm pores. SEM observation of CO
3Ap-collagen sponges showed favorable pores for cells invasion. Mouse osteoblast MC3T3-E1 cells were cultured in α MEM with 10% FCS for 1, 10 and 20 days. Matrix substances on the pure collagen sponge samples increased with the culture period such that the sponge surface was almost covered. A sectional view of hematoxylin-eosin staining confirmed that osteoblast cells had well invaded the CO
3Ap-collagen sponge. When these sponge-frame complexes were implanted beneath the periosteum cranii of rats, newly created bone was observed to grow toward the inner core of the complex from the surface of the periosteum cranii. Based on these results, reinforced CO
3Ap-collagen sponges are expected to be used as hard tissue scaffold Biomaterials for therapeutic purposes.
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Yuko TANAKA, Tsutomu SUGAYA, Masamitsu KAWANAMI
2004 年 23 巻 3 号 p.
265-270
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
4-META/MMA-TBB resin has shown good biocompatibility and remarkable adhesion to dentin. It seems to be suitable for use in periodontal tissues for retrograde root sealing and treatment of vertically fractured roots. For an adhesive resin to be useful clinically, it must bond not only to the dentin but also to the cementum.
The purpose of this study was to evaluate the long-term adhesion durability of 4-META/MMA-TBB resin to cementum kept in water at 37°C. Bovine root cementum and dentin surfaces were treated with 10-3 solution before 4-META/MMA-TBB resin was applied on treated surfaces. The micro-tensile bond strength (μTBS) decreased during the first two months; dye leakage value increased during the first four months and stabilized thereafter. No significant differences in adhesion durability were recognized between the dentin and cementum.
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Tohru HAYAKAWA, Tadao FUKUSHIMA, Kimiya NEMOTO
2004 年 23 巻 3 号 p.
271-277
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to examine the effectiveness of self-etching primer in adhering 4-META/MMA-TBB resin to bovine enamel. In this study, we designed an original self-etching primer which contained an aqueous mixture of 4-MET, 35wt% HEMA, and ferric chloride. The polished bovine enamel surface was treated with self-etching primer for 30 seconds. Tensile bond strength of 4-META/MMA-TBB resin to enamel was measured after 1-day immersion in water at 37°C. The self-etching primer containing 30wt% 4-MET and 35wt% HEMA (4MET30) gave a significantly higher bond strength of 11.2±2.8MPa than other self-etching primers. The addition of ferric chloride into 4MET30 primer significantly decreased tensile bond strength. SEM observation revealed that 4MET30 treatment produced no distinct dissolution on enamel. When compared with phosphoric acid etching, the self-etching primer containing 30wt% 4-MET and 35wt% HEMA was more superior in adhering 4-META/MMA-TBB resin to enamel.
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Mustafa ERSOY, Arzu CIVELEK, Estelle L'HOTELIER, Esra Can SAY, Mubin S ...
2004 年 23 巻 3 号 p.
278-283
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to determine the flexural strength (FS), flexural modulus (FM), depth of cure (DC), polymerization shrinkage (PS), and microhardness (VH) of the following composites:
• Two packable composites - Filtek P-60 and Solitaire 2;
One ion-releasing composite - Ariston AT; and
• Two hybrid composites - Charisma and Filtek Z-250.
Data of the different tests conducted were obtained as follows:
• FS and FM data were determined with a universal-testing machine;
• Polymerization shrinkage was determined using the apparatus of Watts and Cash;
• Depth of cure was measured with a micrometer (Mitotuyo, UK); and
• Microhardness was measured with a Shimadzu Microhardness tester (500g, 15 seconds).
All data of the different tests were statistically analyzed by one-way variance analysis (ANOVA), which yielded the following results:
• Filtek Z-250 showed the statistically highest flexural strength and modulus values.
• Solitaire 2 exhibited the highest shrinkage, while the volumetric shrinkage results of Filtek Z-250 and Filtek P-60 ranked the lowest.
• For depth of cure, there were no statistically significant differences among all materials tested (p<0.05).
• Microhardness results revealed the following tendency: Filtek Z-250=Filtek P-60>Ariston AT=Solitaire 2=Charisma.
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Tomomi SATO, Masashi MIYAZAKI, Akitomo RIKUTA, Kouichi KOBAYASHI
2004 年 23 巻 3 号 p.
284-290
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to develop a method to monitor the free-shrinkage vectors of a light-cured resin using laser speckle contrast measurement. The laser speckle contrast measurement system comprised a semiconductor laser, a speckle analyzer, and a computer-controlled data acquisition system. A light-cured resin was condensed into a glass tube and irradiated using a curing unit, the light intensity of which was adjusted to either 100 or 600mW/cm
2. The speckle patterns obtained from the lateral surface of the specimen were monitored using a CCD camera connected to a computer. The speckle images were analyzed using a phase-only correlation algorithm, and movements of the pattern were traced. The speckle pattern revealed rapid movement almost immediately after light exposure was initiated, and the orientation of free-shrinkage vectors is dependent on light intensity. When the specimens were irradiated at the lower light intensity, the free shrinkage vectors were oriented towards the light source. On the other hand, when irradiated at the higher light intensity, the free-shrinkage vectors of these specimens tended to orient towards the bottom surface. The effectiveness of the employed method to determine free-shrinkage vectors is thus proven through the results of this study.
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Takahito KANIE, Hiroyuki ARIKAWA, Koichi FUJII, Seiji BAN
2004 年 23 巻 3 号 p.
291-296
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to investigate the flexural properties of denture base resin reinforced using glass fiber cloth and a urethane oligomer. The five types of oligomer used in this study were S5, S9, S3, U4, and U6, which have varying functional groups and viscosities. The flexural properties of S9 with glass fiber cloth could not be measured because S9 is elastic. In the heat-cured resin reinforced with S9, the reinforcement peeled away from the resin. In the self- and light-cured resins reinforced with S9, the flexural properties increased significantly. When reinforced with the other four oligomers (S5, S3, U4, and U6), the flexural strength and flexural modulus of the self-, heat-, and light-cured resins increased significantly (p<0.01).
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Yasuhiro TANIMOTO, Kimiya NEMOTO
2004 年 23 巻 3 号 p.
297-304
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to use a tape casting technique to develop an Al
2O
3 fiber-reinforced Al
2O
3-based ceramic material (Al
2O
3-fiber/Al
2O
3 composite) into a new type of dental ceramic. The Al
2O
3-based ceramic used a matrix consisting of 60wt% Al
2O
3 powder and 40wt% SiO
2-B
2O
3 powder. The prepreg sheets of Al
2O
3-fiber/Al
2O
3 composite (in which uniaxially aligned Al
2O
3 fibers were infiltrated with the Al
2O
3-based matrix) were fabricated continuously using tape casting technique with a doctor blade system. Multilayer preforms of Al
2O
3-fiber/Al
2O
3 composite sheets were then sintered at a maximum temperature of 1000°C under an atmospheric pressure in a furnace. The results showed that the shrinkage and bending properties of Al
2O
3-fiber/Al
2O
3 composite exceeded those of unreinforced Al
2O
3 - hence demonstrating the positive effects of fiber reinforcement. In conclusion, the tape casting technique has been utilized to successfully develop a new type of dental ceramic material.
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Effect of Silanized Spherical Silica Filler Addition
Rosalina TJANDRAWINATA, Masao IRIE, Kazuomi SUZUKI
2004 年 23 巻 3 号 p.
305-313
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to investigate the effects of silanized spherical silica fillers (SF) on the immediate and 24-hour marginal gaps of resin-modified glass-ionomer cement (RMGIC) in tooth cavities. In correlation with marginal gap formation in the tooth cavity, these influencing factors were also examined: marginal gap and setting shrinkage of cement in the Teflon mold, as well as the shear bond strength to tooth substrate. Moreover in correlation with caries prevention, fluoride release was examined too.
In this investigation, the fillers were mixed into the RMGIC powder (Fuji II LC EM). Untreated spherical silica filler (UF)-added RMGIC was used as a comparison. When compared with the control (
i.e., original RMGIC), the addition of SF significantly decreased immediate marginal gap in tooth cavities and setting shrinkage in Teflon mold up to 63% and 66% respectively. Fluoride release was significantly reduced too. Apart from these results, this study showed that addition of 5wt% SF increased the shear bond strength to human enamel and dentin.
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Junzo TAKAHASHI, Kazuyoshi KITAHARA, Fuminobu KUBO
2004 年 23 巻 3 号 p.
314-320
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
In this study, new investments for titanium were developed by adding ZrC or ZrN as chemical additive for thermal expansion to a phosphate-bonded zircon (ZrSiO
4) investment. The following effects were then examined: setting expansion, residual thermal expansion, and compressive strength of these experimental investments; surface roughness of cast plate; and casting accuracy of titanium crown. For residual thermal expansion, it occurred even while investments were cooled to room temperature after firing in air atmosphere. This was due to the additives' oxidation to ZrO
2 - suggesting that residual thermal expansion increased with increased amount of these additives. As for casting accuracy of full-crown cast into molds at room temperature, it correlated with the ZrN content. Hence by adding the right amount of ZrN, cast titanium crowns with low surface roughness and good adaptability could be obtained.
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Linlin HAN, Edward CRUZ, Masayoshi FUKUSHIMA, Akira OKAMOTO, Takashi O ...
2004 年 23 巻 3 号 p.
321-328
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
A new type of self-etching agent, the single-step adhesive, was developed. The purpose of this study was to investigate the difference in the ultrastructural features of enamel and dentin surfaces following application of the prototype single-step adhesive (EXM618, 3M, MN, USA). Extracted caries-free human premolars were used in this study. Occlusal enamels of teeth- to be used as cut surface specimens - were removed perpendicular to the long axis of the specimens. The mesial and distal surfaces of these teeth, on the other hand, were used as uncut surface specimens in the test. In addition, Mega Bond (Kuraray Medical Inc., Tokyo, Japan) and Xeno CFII Bond (Dentsply Sankin, Tokyo, Japan) were used as controls. After covering half of the tooth surfaces with nail varnish (for control), the other half of each surface was treated with one of the three test adhesives - EXM618, Mega Bond, or Xeno CFII Bond - according to the manufacturer's recommendations. Conditioned enamel and dentin surfaces (
i.e., decalcified depth and rugged surface) were observed with a scanning confocal laser microscope (SCLM 1100, Olympus, Tokyo, Japan; henceforth abbreviated as SCLM). Based on the findings of this study, the prototype single-step adhesive EXM618 appears to be suitable for use in dental clinics.
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Shinya TAJIMA, Norihiko NISHIMOTO, Yuji KISHI, Shigeki MATSUYA, Kunio ...
2004 年 23 巻 3 号 p.
329-334
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
Effects of added sodium alginate on the mechanical strength of Biopex
®, one type of apatite cement, were investigated since sodium alginate addition is very effective for Biopex
® to acquire anti-washout property. Addition of sodium alginate into the liquid phase of Biopex
® resulted in a slower transformation to apatitic monolith. As a result, mechanical strength of set Biopex
® in terms of diametral tensile strength (DTS) decreased when it was hardened in an incubator kept at 37°C and 100% relative humidity for 7 days. However, DTS value increased with increase in the amount of added sodium alginate when the Biopex
® paste was immersed in 0.9% saline at 37°C for 7 days. Set Biopex
® with less sodium alginate also showed larger porosity. Based on these findings, we concluded that added sodium alginate was effective in increasing the mechanical strength of Biopex
® by inhibiting liquid penetration into its paste when it is exposed to body fluids.
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Yasuaki SHIGA, Ryoji SHIMOGORYO, Tatsuo OKA, Shigeki MATSUYA, Kunio IS ...
2004 年 23 巻 3 号 p.
335-339
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
It is well known that apatite cement causes inflammatory response if it is exposed to blood before setting. In this respect, the hemostatic procedure is very important. However, it has not been clarified how initial hemostasis affects the other basic properties of apatite cement. In the present study, the effect of initial hemostasis on the setting reaction was simulated by allowing the apatite cement paste to be hardened in an incubator for 1 to 30 minutes and then immersed in saline up to 7 days. We found faster transformation of apatite cement to apatitic mineral and higher mechanical strength of the set mass when the cement paste underwent a longer pre-hardening period. We also found that earlier exposure of apatite cement to saline resulted in a set mass with larger porosity. It is thought that the larger porosity of the cement is caused by the penetration of liquid into the cement paste, thus leading to lower mechanical strength and slower transformation of the apatite cement to apatitic mineral. We concluded, therefore, that hemostatic procedure is important not only to prevent inflammatory response but also to obtain a set mass with higher mechanical strength and faster transformation to apatitic mineral.
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Hidekazu AOYAGI, Masataka KATAGIRI
2004 年 23 巻 3 号 p.
340-347
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The aim of this study was to investigate the long-term effects of alloys containing silver (mainly Ag-Sn alloy) on oral mucous tissue. We observed biopsy tissue specimens from patients diagnosed as having amalgam tattoo and/or metal pigmentation by light and electron microscopy and electron-probe microanalysis (EPMA). In most cases, Ag-Sn alloy was present in the tissue but it could not be confirmed if the alloy originated from amalgam. Distributions of both Ag-S and Ag-Sn have typical patterns. Most Ag forms Ag
2S and is stably deposited in three patterns along the collagen, basement membrane, and fibrous cells without inducing any host reaction. On the other hand, Sn forms large granules that contain Ag, S, C, N, P, and Ca, and is in soft state in the tissue. Tissue reactions to the alloy become weaker as time passes.
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Takahiro ONO, Seiichi KITA, Takashi NOKUBI
2004 年 23 巻 3 号 p.
348-352
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to confirm the dimensional accuracy of a newly developed injection pressing method for resin polymerization by making use of the internal electric resistance of resin to determine the optimal timing for resin injection. A new injection pressing polymerization pot with a built-in system to measure the internal electric resistance of resin was used for resin polymerization. Fluid-type resin was injected into the mold of a maxillary complete denture base under nine different conditions: three different timings for resin injection according to the electric resistance of resin dough (early stage: 11MΩ; intermediate stage: 16MΩ; final stage: 21MΩ) and three different motor powers for resin injection (2000N, 4000N, and 6000N) . In the best polymerization condition (injected during the early stage of resin dough under a motor power of 6000N), the adaptation of the denture base showed a statistically significant improvement compared with the conventional pouring method.
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Kiichirou MIMURA, Kouichi WATANABE, Seigo OKAWA, Masayoshi KOBAYASHI, ...
2004 年 23 巻 3 号 p.
353-360
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The present study aimed at morphological and chemical characterization of the coating-substrate interface of a commercially available dental implant coated with plasma-sprayed hydroxyapatite (HA). For this purpose, elements in the chemically and mechanically exposed substrate surfaces were analyzed by EPMA and XPS.
A thin titanium oxide film containing Ca and P was found at the interface. When the implant was subjected to mechanical stress, a mixed mode of cohesive and interfacial fractures occurred. The cohesive fracture was due to separation of the oxide film from the substrate, while the interfacial fracture was due to exfoliation of the coating from the oxide film bonded to the substrate. Analysis showed diffusion of Ca into the metal substrate, hence indicating the presence of chemical bond at the interface. However, mechanical interlocking seemed to play the major role in the interfacial bond.
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Tamayo WATANABE, Masashi MIYAZAKI, Hirohiko INAGE, Hiroyasu KUROKAWA
2004 年 23 巻 3 号 p.
361-367
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to determine the elastic moduli of the components at resin-dentin interface with the use of an ultrasonic device. Dentin plates were obtained from freshly extracted bovine incisors with a shape in rectangular form. Resin composites and bonding agents were polymerized and trimmed in the same shape as the dentin specimens. The ultrasonic equipment employed in this study was comprised of a Pulser-Receiver, transducers, and an oscilloscope. Each elastic modulus was determined by measuring the longitudinal and shear wave sound velocities. The mean elastic modulus of mineralized dentin was 17.4GPa, while that of demineralized dentin was 1.4GPa. When the demineralized dentin was immersed in bonding agents, the elastic modulus changed to 3.7-4.7GPa, and these values were significantly higher than those of demineralized dentin. A gradient in elastic modulus was detected as the analysis shifted from the dentin side to the resin composite.
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Naomi TANOUE, Yoshikazu KOISHI, Hiroaki YANAGIDA, Mitsuru ATSUTA, Kazu ...
2004 年 23 巻 3 号 p.
368-372
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to evaluate the color stability of two acrylic resin adhesives with different activation systems:
a benzoyl peroxide (BPO)-amine redox system and a tri-
n-butylborane (TBB) derivative system. The colorimetric values of
the two resins in different shades (Clear and Ivory) were determined (n=5) 24 hours after polymerization as a baseline
using the L
* a
* b
* system of the Commission Internationale de l'Eclairage (CIE). The specimens were thereafter immersed
in distilled water, and the color difference (ΔE
*) values were calculated. After 24 weeks, the TBB-initiated material showed
a significantly (p<0.05) lower color change than the BPO-amine-initiated material. The ΔE
* values for the BPO-amine-initiated materials were 6.9 for Clear and 15.8 for Ivory, whereas those for the TBB-initiated materials were 1.3 and 1.8 respectively. Thus, it was concluded that the TBB-initiated material had superior color stability to that of the BPO-amine-initiated material.
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Farzaneh AGHAJANI, Zulia HASRATININGSIH, Toshiko MORI
2004 年 23 巻 3 号 p.
373-378
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The degree of III-CaSO
4 to II-CaSO
4 transition was estimated on wet specimens, 25mm in diameter and 50mm high, prepared from a gypsum-bonded investment for quick casting. After 30min from mixing the specimens were heated in a 700°C furnace until a specimen temperature of 200°C to 700°C was reached. The estimation was made by measuring mass changes of the specimens before and after heating. The transition reached 39% at 350°C. The same estimation method, when applied to a previous study, showed no transition to this temperature in dry specimens heated slowly (5°C/min). The large difference in transition found between the wet and dry specimens was attributed to the formation of α- and β-hemihydrate, respectively. At 350-450°C, the transition was 3% and 48%, respectively. The pronounced latter transition, generally identified by differential thermal analysis of gypsum, appears as the major investment shrinkage demonstrating its dry dehydration process.
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Shinji TAKEMOTO, Masayuki HATTORI, Masao YOSHINARI, Eiji KAWADA, Katsu ...
2004 年 23 巻 3 号 p.
379-386
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to investigate the correlation between corrosion resistance and surface composition of an experimental Ti-20mass% Cr casting alloy in a saline solution containing fluoride. The alloy had a greater resistance to corrosion in a fluoride-containing saline solution than did commercially pure titanium. However, with confirmed dissolution of titanium and chromium, it meant that the fluoride in the saline solution corroded the alloy slightly. X-ray photoelectron spectroscopy analysis revealed that the surface composition of the alloy consisted of titanium and chromium oxides containing hydroxide. The [Ti]/([Ti]+[Cr]) ratio in the surface oxide film decreased when immersed in fluoride-containing saline solution, that is, the surface oxide film became chromium-rich oxide. Therefore, the alloy obtained good corrosion resistance to fluoride due to formation of a chromium-rich oxide film.
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Hisaji KIKUCHI, Makoto ONOUCHI, Kohichi MIYANAGA, Mitsuru WAKASHIMA, O ...
2004 年 23 巻 3 号 p.
387-394
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
In this study, wedge-shaped CP titanium castings and Ti-6Al-7Nb alloy castings were produced by three types of investment. The effects of the castings' thickness on surface reaction layer were investigated by measuring Vickers hardness, observing the microstructure, and analyzing the oxygen concentration. It was found that the thickness of the surface reaction layer was affected by the thickness of the wedge-shaped castings, and that the hardness value near the surface became lower to-ward the tip of the wedge-shaped CP titanium and Ti-6Al-7Nb alloy castings. The surface reaction layer of the Ti-6Al-7Nb alloy castings was thinner than that of the CP titanium castings.
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Yukinori MARUO, Masao IRIE, Goro NISHIGAWA, Morihiko OKA, Shogo MINAGI ...
2004 年 23 巻 3 号 p.
395-398
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
This study aims to investigate the preferred viscosity of irreversible hydrocolloid used in the preliminary impression for edentulism. Thirteen modalities of irreversible hydrocolloid were prepared by changing the W/P ratio. Discrimination test for the preferred viscosity was performed on 11 prosthodontists (10.4±5.3 years of prosthetic experience). The parameter of discrimination test (P%) was calculated as the ratio of the number of adequate tests to the total number of tests. The P% and apparent viscosity coefficient (ηa) values measured by rheometer demonstrated good correlation (Y=-35.8X
2+118.4X-22.8, r=0.86, p<0.01). Prosthodontists could judge the preferred viscosity based on their clinical experiences. On the preliminary impression for edentulism, the preferred viscosity demonstrated in vitro using a polyurethane maxilla model was 1.21×10
3 Pa⋅s.
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Cavity Liner and Pulp Capping Agent
Masahiro SAITOH, Shigeyuki MASUTANI, Taishi KOJIMA, Masataka SAIGOH, H ...
2004 年 23 巻 3 号 p.
399-405
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
We studied the thermal properties of cavity liners that included calcium phosphate as inorganic filler, in contrast to the conventional pulp capping agents. Therefore, thermal diffusivity, specific heat capacity, and thermal conductivity were measured. In addition, thermal conductivity results were compared with those of restorative materials and human dentin to examine thermal insulation effects. The thermal conductivity of cavity liners ranged from 0.23 to 0.28Wm
-1K
-1, and that of pulp capping agents ranged from 0.44 to 0.48Wm
-1K
-1. Test results indicated that the thermal conductivity of cavity liner was lower than those of human dentin, pulp capping agent, cast alloy, and composite resin for restoration, hence suggesting that cavity liner has a good thermal insulation effect.
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Koichi MURAGUCHI, Shiro SUZUKI, Hiroyuki MINAMI, Takuo TANAKA
2004 年 23 巻 3 号 p.
406-411
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
This study investigated the stability of a resin-paint material (Master Palette) - which was developed for chairside shade modification of composite restorations - by evaluating its bond strength to indirect resin composite and surface degradation. Bond strength was evaluated with four surface treatments including an application of methylene chloride, airborne particle abrasion with 50μm aluminum oxide, and additional applications of bonding agents after air-abrasion. The surface roughness (Rz value) of both the resin-paint and indirect resin composite before and after thermo-cycling (4-60°C, 50, 000 cycles) was also evaluated. All data were statistically analyzed by two-way ANOVA and Boneferroni's test (p=0.05). It was found that bond strength was improved by bonding agent application (14.9±1.9MPa to 18.6±2.2MPa, p<0.0054) after thermo-cycling. As for surface roughness, its results after thermo-cycling (2.7±0.2μm, p<0.001) demonstrated that the resin-paint needed further improvements to maintain the original surface texture.
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Yoshiya HASHIMOTO, Masaaki NAKAMURA
2004 年 23 巻 3 号 p.
412-418
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
We prepared prototype phthalate ester-free tissue conditioners (PFT) from a powder of poly (ethyl methacrylate) and a mixture of several liquids, including di-n-butyl sebacate, benzyl benzoate (BB), and ethanol. The estrogenic activities of the liquids in the PFT were measured by an E-screen assay. We also assessed the cytotoxicity of the prototype and commercial tissue conditioners against a living skin equivalent. Finally, the viscoelastic properties were determined by measuring the rubber hardness and initial flow, while the effect of the mixing liquid on the mechanical properties of a denture resin was assessed by three-point bending test. PFT did not show any estrogenic activity and displayed a low or a similar level of cytotoxicity as the conventional materials. The viscoelastic properties and the effect of the mixing liquid on mechanical properties were influenced by the quantity of BB present in the mixing liquid. The prototype is therefore a reasonable PFT candidate.
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Kentaro SHINDO, Yutaka KAKUMA, Haruki ISHIKAWA, Chihiro KOBAYASHI, Hid ...
2004 年 23 巻 3 号 p.
419-423
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The aim of this study was to evaluate the sealing ability of materials filled in the orifice after root canal treatment. A total of 100 root canal-treated teeth were divided into six experimental groups: 1, Protect Liner F (PL); 2, Panavia F (PF); 3, DC core-Light cured (DCL); 4, DC core-Chemically cured (DCC); 5, Super-EBA (SE); 6, Ketac (KC). The materials were filled - to a depth of 4mm - in the coronal part of the root canals, and evaluated for microleakage.
The number of teeth that failed to stop dye penetration in the filled materials differed statistically between PL and DCL or SE or KC, PF and SE or KC, DCC and KC, DCL and KC. The mean distance of dye penetration differed significantly between PL and SE or DCC, PF and SE or DCC. Hence, these results indicated the advantageous sealing ability of adhesive and flowable materials.
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Seiji BAN, Akihiko KADOKAWA, Takahito KANIE, Hiroyuki ARIKAWA, Koichi ...
2004 年 23 巻 3 号 p.
424-428
発行日: 2004年
公開日: 2009/02/12
ジャーナル
フリー
The shear bonding strengths of a veneering resin to polished, sandblasted, and retention bead-cast commercially pure titanium (cpTi) plates with and without alkaline treatment were measured before and after thermal cycling. The bonding strengths to polished cpTi with and without alkaline treatment decreased remarkably with thermal cycling (p>0.01). The bonding strength to sandblasted cpTi with alkaline treatment at 5, 000 thermal cycles showed no significant differences from those before thermal cycling (p<0.05), and those at 20, 000 thermal cycles showed values which were quite small (p>0.01). On the other hand, there were no significant differences in the bonding strengths of veneering resin to retention bead-cast cpTi in all conditions (p<0.05). These results suggested that although alkaline treatment is a simple and effective surface modification technique for titanium improving adhesion to resin due to formation of tight-fine rutile particles, it does not provide sufficient bonding durability for long-period restorations.
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Yavuz GÖMEÇ, Can DORTER, Handan ERSEV, Begüm GURAY EF ...
2004 年 23 巻 3 号 p.
429-435
発行日: 2004年
公開日: 2009/03/27
ジャーナル
フリー
The aim of this
in vitro study was to investigate if surface microhardness of Fuji IX GP, Vitremer, Dyract AP, and Prodigy is influenced by conditioning in aqueous solutions of lactic, orthophosphoric, citric, and acetic acids against bidistilled water (which was used as control). The pH values of acids used in this study were representative of dietary acids. All specimens were stored in bidistilled water for one week and then conditioned in the respective test solutions for another week. Citric (p<0.05) and acetic acids reduced, while lactic and orthophosphoric acids (p<0.05) increased the microhardness of both Fuji IX GP and Vitremer. On the other hand, microhardness of both Dyract AP and Prodigy was significantly reduced by all acidic media (p<0.05). The observed differences in the surface microhardness of various tooth-colored restorative materials conditioned in several media varied not only with the pH but also the nature of the acidic solution, and with the composition of the evaluated material.
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