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Volume 7 (1988)
- Issue 2 Pages 141-
- Issue 1 Pages 1-
Volume 7, Issue 2
Displaying 1-9 of 9 articles from this issue
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Ikuro HARASHIMA, Tadashi HIRASAWA, Kentaro TOMIOKA, Jun-ichi OKADA1988 Volume 7 Issue 2 Pages 141-150,231
Published: December 25, 1988
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThree isomers of methacryloyloxyethyl naphthalenetricarboxylate anhydrides (MENTA-126, -236 and-184) were synthesized, and their adhesiveness to teeth and non-precious dental alloys was investigated.
The MENTA resins initiated by TBB-O showed about 12-13MPa of the bond strength on treated enamel and 10-12.5MPa on treated dentin after 120 thermocycles, while, after the equal thermal cyclings, the values of the control resin were 8.3MPa for the enamel and 5.2MPa for the dentin. In the case of the bonding to dental Ni-Cr and Co-Cr alloys, MENTA-126 and -236 possessing the five-membered dicarboxylic anhydride ring structure were more effective than MENTA-184, which has the six-membered ring. The bond strengths to these alloys were 9.4-11.3MPa for the MENTA-126 resin and 7.5-16.5MPa for the MENTA-236 resin. The bond strengths of the MENTA-184 resin were 1.9MPa for Ni-Cr and 4.6MPa for Co-Cr. These values were comparable to the control.View full abstractDownload PDF (2712K) -
Ikuro HARASHIMA, Tadashi HIRASAWA, Kentaro TOMIOKA, Jun-ichi OKADA1988 Volume 7 Issue 2 Pages 151-159,231
Published: December 25, 1988
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe failure of bonding between tooth substrates and the light-cured bonding resin containing 6-methacryloyloxyethyl naphthalene-1, 2, 6-tricarboxylate anhydride (MENTA-126) was examined by fractography. The dependence of the bond strength on the infiltration of the monomer into dentin was also investigated.
Scanning electron microscopic fractographs of failed bonding to treated enamel showed a cohesive fracture in the resin. Fractographs of the bonding to treated dentin suggested a complex failure including an interface fracture between the resin and the dentin and cohesive fractures in the resin and just under the resin-infiltrated dentin layer. The bond strength was slightly dependent on the infiltration of the monomer only when dentins treated with an aqueous solution of 10% citric acid and 3% FeCl3 were employed. In the other cases examined, there was not any significant dependence.View full abstractDownload PDF (4347K) -
Nobutake KANEMATSU, Hironori TSUCHIYA, Masaru SATO, Kohji YAMAMOTO, Sh ...1988 Volume 7 Issue 2 Pages 160-165,232
Published: December 25, 1988
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe cytotoxic effects of several commercial Ni-Cr base alloys were investigated by a cell culture study using mouse fibroblasts (L929). Their toxicities were estimated based on cell survival and colony formation rates compared with the control (glass) after cultivating the cells with the alloy plates. All of the alloys uniformly showed cytotoxicities in cell survival and colony formation, but the toxic potency was different among the alloys. The cytotoxicity of authentic Ni-Cr binary alloys closely correlated to the leaching of Ni from the alloys. Both the cytotoxicity and leaching were dependent on the Cr content in the alloys and were abruptly increased at Cr contents lower than 15%. However, the degree of cytotoxicity in commercial Ni-Cr base alloys could not only be attributed to a correlation between Ni leachability and Cr content relative to Ni. This result may be interpreted by the participation of other components such as Co, Cu, etc. and/or the Cr content-dependent ununiformity in the alloys.View full abstractDownload PDF (1315K) -
Part 1 A New Method for Determination of Impact PropertiesJun-ichi OKU1988 Volume 7 Issue 2 Pages 166-173,232
Published: December 25, 1988
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe impact properties of polymethyl methacrylate (PMMA) denture base resins were examined using an impact testing machine. Within the range of specimen cross-sectional area from 3.2mm2 to 7.2mm2, the impact strength, resilience and toughness increased markedly according to an increase in the cross-sectional area without the V-notch portion. However, these three properties decreased linearly with an increase in distance (span) between the supporting points of the specimen. In the case of a cold cured resin, the modulus of rupture and resilience increased slightly with time after the polymerization, and the impact strength and toughness showed a slight decrease.View full abstractDownload PDF (1204K) -
Minoru KAWAGUCHI, Tadao FUKUSHIMA, Takashi HORIBE1988 Volume 7 Issue 2 Pages 174-181,232
Published: December 25, 1988
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe visible light-cured unfilled resins using the nine types of aromatic dimethacrylates were investigated to determine the effects of the monomer structure on selected properties. Analysis of the data indicated that the mechanical properties of these unfilled resins were much dependent upon the monomer structure. There was also a correlation between the water sorption value of the unfilled resins and the reduction in their mechanical properties under wet conditions. The results of this investigation indicated that the fluoro groups-containing dimethacrylate resin would be the effective resin system for visible light-cured dental restorative materials.View full abstractDownload PDF (2017K) -
Hiroyuki ARIKAWA, Katsuichiro INOUE1988 Volume 7 Issue 2 Pages 182-187,233
Published: December 25, 1988
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe dynamic shear modulus of human dentin was measured using a torsion pendulum between 23°C and 150°C. Dentin had a relatively stable modulus in spite of increasing temperature. The shear moduli at 37°C for 20 specimens were in the range of 5.77×1010 dyne/cm2-1.06×1011 dyne/cm2. These values differed little from that for composite resins (6.77×1010 dyne/cm2). The peak in the distribution curve of the mechanical loss tangent was observed at nearly 75°C. The values for the loss tangent were markedly low in comparison with that for composite resins. Though the number of samples was small, it seemed that there was no significant correlation between the shear modulus and the patient's sex, age and tooth type.View full abstractDownload PDF (869K) -
Part 1. Characteristic Aspects and Correction of MKG RecordsMasao MORIKAWA, Masahiro SAKO, Hirofumi KIDO, Sizuo TOYODA, Yoshio KOZ ...1988 Volume 7 Issue 2 Pages 188-196,233
Published: December 25, 1988
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSFor the purpose of applying the mandibular kinesiograph (MKG) to the analysis of the abutment tooth movement to evaluate the partial denture design, the characteristic aspects of the MKG record were examined. The rectangular lattices resulting from shifting the magnet in the mesio-distal, right-left, and up-down directions were considerably distorted on the display. However, it was assumed that the three dimensional movement of the tooth could be approximately estimated by a simple correction of the record utilizing those distorted lattices in the sagittal, frontal and horizontal views. If only the record is appropriately interpreted on the basis of the characteristic aspects of the MKG, the MKG method may be valid for estimating the abutment tooth movement in evaluating the design of partial prostheses.View full abstractDownload PDF (1278K) -
IV. Cooling Condition to Minimize the Residual Thermal StressYoshima ARAKI, Naoyuki KATAKURA, Michio KAWAKAMI1988 Volume 7 Issue 2 Pages 197-205,234
Published: December 25, 1988
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe optimal cooling conditions used to minimize the residual thermal stress in wax patterns were derived theoretically from the uniaxial thermal stress equation by using Euler-Lagrange's method. This was calculated for three brands of casting waxes. The optimal condition thus obtained gave an approximately minimum stress of many conditions arbitrarily established. The optimal cooling was such that the reduced time, derived from the time-temperature superposion principle, might be long for stress relaxation in a given period. In a short time (10min and 30min), the residual stresses were not much different between the optimal cooling and spontaneous cooling, but after 5 hours, the stress under optimal cooling was half the value of the spontaneous cooling.View full abstractDownload PDF (1311K) -
Wen-Jyh ROU, Po-In CHANG, Yohji IMAI1988 Volume 7 Issue 2 Pages 206-216,234
Published: December 25, 1988
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe wear level of restorative materials in class V cavities was evaluated by a new in vitro method using a tooth brushing apparatus. The result corresponded well with clinical findings. The conventional composite resin showed a higher abrasive resistance than the enamel surface, while the glass ionomer cement and light cure composite (BF) showed an abrasive resistance equal to the enamel surface. Though the wear resistance of 4-META/MMA (S) was low, the PMMA-acrylic resin containing dimethacrylate showed an improved wear resistance. The wear resistance of S and PA samples after 30min brushing which equal to two years of intraoral tooth brushing showed comparable wear resistance to C, PC and I samples'. From the SEM photographs, all the composite resin surface showed obviously rough surfaces compared to unfilled resins after 30min of brushing. Unfilled resin may be worth being reconsidered in class V restorations from an esthetic point of view.View full abstractDownload PDF (5247K)
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