-
Takahito KANIE, Hiroyuki ARIKAWA, Koichi FUJII, Seiji BAN
2003 年 22 巻 4 号 p.
425-435
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
In this study, the L
*a
*b
* color system as a color system and light transmittance of the denture base resin reinforced with wire mesh and glass cloth were measured, and the color difference (ΔE
* ab) was calculated using L
*, a
* and b
* values which were measured both on a white calibration plate and on a null background. The thicknesses of test specimens, which were reinforced with wire mesh and glass cloth 0.5 and 1.0mm below the surface, were 3 and 5mm. L
*, a
* and b
* values of wire mesh reinforcing specimens decreased in comparison with the non-reinforcing specimens (
p<0.05). L
* values of glass cloth-reinforcing specimens increased compared with the non-reinforcing specimens (
p<0.05). The glass cloth is an effective reinforcing material and an aesthetically important property of denture base resin, since wire mesh makes the resin appear darker with the background condition greatly altering the color, while glass cloth makes the resin lighter.
抄録全体を表示
-
Visualization of Temperature Distribution on Oral Tissues
Manabu KOMORIYAMA, Rie NOMOTO, Rin TANAKA, Noriyasu HOSOYA, Kazuhiro G ...
2003 年 22 巻 4 号 p.
436-443
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to devise and propose appropriate conditions for the photographing of thermal images in the oral cavity and to evaluate which thermography techniques can be applied to dentistry by evaluating the differences in temperature among oral tissues.
Thermal images of oral cavities of 20 volunteers in normal oral condition were taken according to the guidelines of the Japanese Society of Thermography, with five added items for oral observation.
The use of a mirror made it possible to take thermal images of the posterior portion or palate. Teeth, free gingiva, attached gingiva and alveolar mucosa were identified on thermal images. There were differences in temperature between teeth, free gingiva, attached gingiva and alveolar mucosa. These were nearly in agreement with the anatomical view. Thermography need no longer be restricted to the anterior portion using a mirror, and can now be applied to the dental region.
抄録全体を表示
-
Nuran DINÇKAL YANIKOGLU, Saip DENIZOGLU
2003 年 22 巻 4 号 p.
444-451
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this
in vitro study was to compare the tear energy of three silicone rubber materials and two acrylic resin soft lining materials in different solutions and times of storage. The tear energy of specimens stored in artificial saliva, denture cleanser and distilled water was measured over 1, 4, and 16 weeks, using a tensile testing machine.
Data were analyzed with a one-way analysis of variance and a Duncan multiple compari-son test. Silicone rubber materials had the least tear energy. The type of material, time of storage and solution were statistically significant factors affecting on tear energy. The ability of the material to resist rupture during normal use (including constantly being in saliva and usually immersed in denture cleanser or water for storage) is of practical importance.
抄録全体を表示
-
Noriko HORASAWA, Shigeo TAKAHASHI, Miroslav MAREK
2003 年 22 巻 4 号 p.
452-459
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
In this study an immersion and fracture test was used to evaluate the susceptibility of dental amalgams to degradation of their mechanical strength by corrosion. Specimens of each of the six types of high-copper amalgams and one type of low-copper amalgam were prepared and tested. Cylindrical specimens were grooved using a diamond cutoff blade and immersed in 1% NaCl to which H
2O
2 was added to increase the oxidation power. After two weeks of exposure the specimens and controls were fractured and the loss of strength was calculated. Two amalgams showed a significant loss of strength. The test procedure is relatively simple and does not require sophisticated electrochemical or analytical instrumentation. A higher resolution power might be achieved by increasing the severity of corrosion or the number of replicate tests.
抄録全体を表示
-
Zeynep YESIL DUYMUS, Recep ORBAK, Alparslan DILSIZ
2003 年 22 巻 4 号 p.
460-466
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
This study was carried out to comparatively examine abrasion which occurred as a result of brushing as well as abrasives in veneering materials used in prosthetic restorations. Twenty out of forty specimens prepared at the dimensions of 14×5×3mm, there being ten specimens of each veneering materials, were subjected to tooth brushing with water alone. The other twenty specimens were subjected to a tooth brushing procedure with a paste- water mixture with the aim of evaluating the effects of abrasives on abrasion. As a result, it was statistically determined that porcelain, an ideal facet material, had the best resistance to abrasion by toothbrush, light cured aesthetic materials being second Poly methyl methacrylate had the least abrasion resistance.
抄録全体を表示
-
Seiji BAN
2003 年 22 巻 4 号 p.
467-474
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
The electrochemical deposition process of apatite was monitored in real-time using an electrochemical quartz crystal microbalance (EQCM). A piezoelectric quartz oscillator with titanium was fixed to a cell and connected to a frequency counter. The electrolyte temperature was maintained at 20, 37, and 60°C and the direct current density was constant at 0.2, 0.5, 1.0, and 2.0mA/cm
2. The deposited amount derived from the frequency change increased as electrolyte temperature and current density increased. The critical times, which are the starting times of quick increases of deposition, decreased with them. The critical times observed in the present study, namely
in situ, were much shorter than those obtained from real weight change reported in our previous report. The apparent activation energies of the electrochemical deposition of apatite under 1.0 and 2.0mA/cm
2 were about 36.1 and 31.9kJ/mol, respectively. These results indicate that electro current loading may reduce the activation energy required for the deposition of calcium phosphates.
抄録全体を表示
-
Can DORTER, Esra YILDIZ, Yavuz GOMEC, Dina ERDILEK
2003 年 22 巻 4 号 p.
475-481
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
The purpose of this study was to evaluate the effect of toothbrushing on the surface roughness and microhardness of Admira and Definite following acid conditioning. Half of the samples were either used as controls or brushed for 10 minutes using an electric toothbrush with slurry. The remaining specimens were stored in orthophosphoric acid with a pH of 1.9 for 24 hours and then half were brushed. The surface roughness of Admira and Definite was not significantly affected by storage under acidic conditions. However, the specimens of both materials in the control groups and the ones tested after acidic storage were found to be significantly smoother than the specimens subjected to toothbrushing alone and brushing following acid conditioning. For both materials, significantly higher values of microhardness were obtained after toothbrushing following acid conditioning than toothbrushing alone. Therefore, brushing following acid conditioning significantly affects the surfaces of the ormocers.
抄録全体を表示
-
Hongwei DONG, Yuki NAGAMATSU, Ker-Kong CHEN, Kiyoshi TAJIMA, Hiroshi K ...
2003 年 22 巻 4 号 p.
482-493
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
The corrosion behavior of dental alloys was examined in electrolyzed strong acid water, weak acid water and neutral water using a 7-day immersion test. The precious metal alloys, gold alloy, Au-Ag-Pd alloy and silver alloy showed the greatest surface color change and dissolution of constituents in the strong acid water and the smallest in the neutral water. The release of Au from gold alloy was especially marked in the strong acid water. Co-Cr alloy showed greater corrosion and tarnish resistance in the strong acid water rather than in the weak acid water and the neutral water. X-ray microanalysis revealed that the corrosion products on the precious metal alloys were silver chloride crystals and the thin brown products on Co-Cr alloy were cobalt and chromium oxides. Ti was sound in all three types of electrolyzed water. The neutral water appeared the least corrosive to metals among the three types showing equivalent bactericidal activity.
抄録全体を表示
-
Hisako HIRAGUCHI, Hisami NAKAGAWA, Hirobumi UCHIDA, Naoki TANABE
2003 年 22 巻 4 号 p.
494-506
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
This study investigated the effect of rinsing alginate impressions using acidic electrolyzed water on the dimensional change and deformation of stone models.
Two brands of alginate impression materials were used. The impressions were rinsed using tap water or acidic electrolyzed water with a pH of 2.3, an oxidation-reduction potential of 1, 230mV, and a residual chlorine concentration of 45.0ppm for 30sec or 3min. The sectional profiles of the stone models obtained from them were measured using a threedimensional coordinate measuring system.
For the same rinsing time, there was no significant difference in dimensional change between the two types of rinsing water. The change in shape from the master die was approximately the same for the stone models obtained from rinsed impressions using either water. The results suggest that the use of acidic electrolyzed water rather than tap water for rinsing is an acceptable treatment for alginate impressions.
抄録全体を表示
-
Syuhei KURODA, Shoji TAKEDA, Masaaki NAKAMURA
2003 年 22 巻 4 号 p.
507-520
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
The effects of six particulate metals (Al, Ti, Zr, Nb, Ta and Cr) on cell viability and alkaline phosphatase (ALP) activity were studied
in vitro using two types of osteoblast-like cells, MG-63 and HOS cells. The cell viability in the presence of Al, Ti and Zr was depressed at lower concentrations than in the presence of Nb, Ta and Cr. The average sizes of the Al, Ti, Zr, Nb, Ta and Cr particulates were 6.48μm, 16.99μm, 5.07μm, 14.18μm, 8.32μm and 23.27μm respectively. The interaction of HOS cells with the particulates was more sensitive than that of MG-63 cells. ALP activity increased at higher concentrations only with the Al particulates; other experimental conditions did not exert an influence on ALP activity. These findings suggest that the cell viability of osteoblast-like cells might be influenced by particulate size and metal type, but ALP activity was not influenced by these factors.
抄録全体を表示
-
(II) Investment for the Quick Casting Technique
Toshiko MORI, Farzaneh AGHAJANI
2003 年 22 巻 4 号 p.
521-531
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
Part I of this study presented a hypothesis that the thermal expansion of gypsum-bonded investment should become higher under heating conditions favorable for the formation of α-hemihydrate. The present study aimed at proving this hypothesis by simulating the rapid heating condition employed in the quick casting technique. The expansion values obtained were 1.72-1.93% after 30min in three investments, two rapid heating and one conventional types. Under a comparable measuring pressure a common laboratory measurement (5°C/min) gave significantly lower expansions of 1.32-1.36% at 700°C for the same investments (p<0.01). The shrinkage observed at 350-400°C in this measurement was not observed in the rapid heating. Realistically large molds prepared from the conventional gypsum-bonded investment need to be investigated for their potentially high thermal expansion.
抄録全体を表示
-
Yoshifumi HIGASHINO, Mutsuo YAMAUCHI, Takayasu GOTO, Toru NAGASAWA
2003 年 22 巻 4 号 p.
532-542
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
To elucidate the cause of brittleness of porcelain fused to pure titanium (PFPT) which leads to Chipping and cracking similar to that of conventional porcelain in clinical use, fracture toughness KIc, hardness (Hv and Hk) and fracture energy Γ reflecting the bonding energy of atoms were evaluated. In KIc there were no differences between PFPT and conventional porcelain, nor for Hv and Hk, but for the Γ of PFPT calculated from the KIc and the Young modulus measured by the resonance method there was less than that of conventional porcelain. These results indicate that mechanical properties such as KIc and hardness cannot always substantiate the brittleness of PFPT experienced in practical use. However, a comparatively small Γ of PFPT may suggest a fatigue crack growth as a more likely phenomenon as it occurs more easily than the conventional one in oral.
抄録全体を表示
-
Hiroko SOMA, Yukio MIYAGAWA, Hideo OGURA
2003 年 22 巻 4 号 p.
543-555
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
A metal-resin composite material was experimentally prepared by mixing a powder consisting of Ag-Cu particles and BPO with a paste consisting of UDMA-based monomer and 4-META in the absence of tertiary amine. The working time and setting time were mainly affected by the amounts of 4-META, BPO and metal particles, most of them fulfilling the requirements for working time and setting time specified in ISO4049: 2000 in the present experimental conditions. The flexural strength ranged from 49.6MPa to 77.8MPa, and the highest value was obtained when the 4-META concentration was high and metal particle content was low. The flexural modulus of elasticity, ranging from 6.7GPa to 11.9GPa, significantly increased as the 4-META concentration and metal particle content increased. Based on its mechanical properties, this metal-resin composite in which metal particles are involved in the polymerization initiation system has the potential to be used as a dental restorative material.
抄録全体を表示
-
Magda Kiyoko YAMADA, Fumio WATARI
2003 年 22 巻 4 号 p.
556-568
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
Two types of non-contact optical profilometers, one performing scanning electron microscopy (SEM) installed with a 3D analyzer and another performing confocal laser scanning microscopy (CLSM) were applied to evaluate imaging and surface profiles simultaneously on enamel and dentin after Nd: YAG laser irradiation. The results were correlated with a stylus profilometer. Surface roughness (Ra) was also measured. Laser was applied perpendicularly to vertical sections of human extracted caries-free molars. Analysis was done on the same spot of the same specimen by both SEM and CLSM for comparison. After irradiation, enamel produced a flake-like surface and dentin resulted in a melted globule surface. SEM and CLSM gave similar surface profiles and different image contrast. The Ra obtained by CLSM was larger than that by SEM. Both SEM and CLSM provided a non-contact evaluation of tooth structural change by laser irradiation through surface analysis in selected micro areas, which was not possible using the stylus profilometer.
抄録全体を表示
-
Kazutoshi TANI, Fumio WATARI, Motohiro UO, Manabu MORITA
2003 年 22 巻 4 号 p.
569-580
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
The differentiation of composite resin from teeth using fluorescence emission was investigated as basic research for the visual detection of resin filled teeth in mass dental health examinations. Fluorescence spectra were taken from extracted human maxillary central incisors and 12 types of light-cured composite resins with a maximum of 15 shades via excitation using light with wavelengths of 400∼500nm. The fluorescence intensity ratio of resin to tooth was lowest around 500nm for all the resins. The fluorescent images were taken based on spectroscopic results, which confirmed discrimination between the resin part and the tooth in the resin filled tooth.
抄録全体を表示
-
Sonosuke FUJIOKA, Kazutoshi KAKIMOTO, Taro INOUE, Joji OKAZAKI, Yutaka ...
2003 年 22 巻 4 号 p.
581-591
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
It is not known for certain that dental stone components influence titanium welding. In this study, we investigated metallurgical problems caused by laser welding on dental stones using wrought commercial pure (CP) titanium. A pulsed Nd: YAG laser irradiated a number of specimens' surfaces which were fixed on either a dental hard stone or a titanium plate. The metallurgical properties of the weld were evaluated using the Vickers hardness test, microstructure observation, fractured surface observation and quantitative analysis of oxygen and hydrogen. In the weld formed on the dental stone there was an increase in hardness, the existence of an acicular structure and a brittle fractured surface, and an increase in the oxygen and hydrogen concentrations compared with base metal. In the weld formed on the titanium plate, these changes were not observed. Therefore, it was demonstrated that laser welding on dental stones made the welds brittle.
抄録全体を表示
-
Funda BAYINDIR, M. Samil AKYIL, Yusuf Ziya BAYINDIR
2003 年 22 巻 4 号 p.
592-599
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
This present study had three aims: 1) to evaluate the bond strengths of carboxylate and resin cements in cementing cast Co-Cr crowns to pretreatment of composite resin cores with eugenol and non-eugenol containing temporary cements, 2) to determine the microhardness of composite resin treated with temporary cement, 3) to view the surface differences of composite resin with SEM.
The composite cores were divided into three experimental groups for the following pretreatments: Group 1, No treatment was provided, Group 2, The external walls of the composite cores were covered with eugenol-containing temporary cement, Group 3, The external walls of the composite cores were covered with non-eugenol containing temporary cement.
Analysis of variance results showed that there was a significant difference between all three groups. Temporary cement with eugenol was significantly reduced the bond strength of full crown casting with resin cement compared with non-eugenol.
The resin specimens treated with the eugenol-containing temporary cement showed the lowest microhardness values, the non-eugenol-containing temporary cement was not significantly different from those of the control groups.
抄録全体を表示
-
Ali Kemal ÖZDEMIR, Nilüfer Tülin POLAT
2003 年 22 巻 4 号 p.
600-609
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
The aim of this study was to evaluate the effect of glass fiber distribution on the transverse strength and surface smoothness of conventional heat cured acrylic and autopolymerizing acrylic of an injection-molding system.
Forty rectangular (65×10×2.5mm) acrylic test specimens were prepared from both acrylic types: 10 with 5% (w/w) 6mm length fiber and 10 without fiber for both groups. Transverse strength test was applied to these specimens. Surface samples were taken from the broken and polished surfaces of these specimens and evaluated using SEM.
The addition of fiber was found to cause a statistically significant increase in the transverse strength of the injection system's acrylic. In SEM observation it was revealed that there was good adhesion between glass fiber and both acrylic resins. The glass fibers distribution was more even in the injection system's acrylic. It is suggested that injection system's acrylic be fiber-reinforced to reduce denture fractures.
抄録全体を表示
-
Yusuf Ziya BAYINDIR, Mehmet YILDIZ, Funda BAYINDIR
2003 年 22 巻 4 号 p.
610-616
発行日: 2003年
公開日: 2009/02/12
ジャーナル
フリー
at low intensity followed by a post-light-cure at full intensity (soft-start polymerization) may lead to light-cured composite fillings with improved marginal integrity. The aim of this study was to examine the influence of soft-start polymerization with different protocols on Vickers hardness of different packable composites.
Vickers hardness of packable composites ALERT, and Definite were measured with a Vickers indenter and were evaluated. The results suggested that independent of the applied curing mode and curing tip, Alert showed significantly higher Vickers hardness than did Definite (p<0.05). There was no significant influence of curing mode or light guide on Vickers hardness of the samples tested.
In conclusion, we found that soft-start polymerization does not have a significant influence on the degree of conversion, when compared with the conventional method. In addition, different light tips showed no significant improvement on surface hardness.
抄録全体を表示
