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Volume 11 (1992)
- Issue 2 Pages 119-
- Issue 1 Pages 1-
Volume 11, Issue 1
Displaying 1-10 of 10 articles from this issue
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Takayuki YONEYAMA, Hisashi DOI, Hitoshi HAMANAKA, Yasuo OKAMOTO, Masak ...1992 Volume 11 Issue 1 Pages 1-10,111
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSBending properties and thermal behavior of twenty commercial Ni-Ti alloy orthodontic arch wires were investigated quantitatively to characterize their suitability for clinical use. There was substantial difference among the load-deflection curves obtained by a three-point bending test. Some wires exhibited superelasticity; load decreased little with decreasing deflection. Others showed good spring-back properties only; load was nearly proportional to deflection. Thermal behavior due to phase transformation of the alloy was examined by differential scanning calorimetry (DSC). Some of the wires did not have the correct transformation temperatures to exhibit super-elasticity at body temperature. Moreover, thermal behavior was closely related to super-elasticity. There were clear thermal peaks in the DSC curves of the super-elastic wires. However, wires without super-elasticity had no peak in the DSC curves.View full abstractDownload PDF (1347K) -
Akiyoshi SUGAWARA, Minoru NISHIYAMA, Kaoru KUSAMA, Itaru MORO, Satoshi ...1992 Volume 11 Issue 1 Pages 11-16,111
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSCalcium phosphate cement (CPC) consisting of Ca4(PO4)2O and CaHPO4 (2H2O) was recently developed. This study evaluated in vivo aspects of CPC and CPC mixtures compared to those of commercial hydroxyapatite (HP) and several endodontic materials: Grossman's cement (GC), calcium hydroxide-iodine paste (CHP) and gutta-percha plate (GP).
Biocompatibility of subcutaneous implants in Donryu rats was evaluated after one month. Results showed very slight inflammatory reactions from CPC, CPC mixtures and HP. The materials were surrounded by thin fibrous connective tissues with a small number of lymphocytes and plasma cells. Severe inflammatory reactions were provoked by GC. Granulation tissues induced by CHP resembled those of pseudoxanthomatous granuloma. The GP material was encapsulated by relatively thick fibrous connective tissues with little inflammatory reactions.View full abstractDownload PDF (1708K) -
Seiichiro FUJISAWA, Yasuo KOMODA, Yoshinori KADOMA1992 Volume 11 Issue 1 Pages 17-25,112
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSN-methacryloyloxy-5-aminosalicylic acid (MASA) has recently been used as an adhesive primer in restorative resin systems. To monitor the biological activity of MASA, we studied changes in NMR-chemical shifts (δH) and the differential scanning calorimetry (DSC) phase transition temperature (Tm) of dipalmitoylphosphatidylcholine (DPPC)/MASA liposomes with or without the presence of albumin and collagen. The δH and the Tm did not alter significantly and the interaction of MASA with DPPC was found to be small. Hemolytic activity of MASA was markedly smaller than that of the phosphate monomer (MDP) in bonding agents widely used. These findings suggest that using a MASA primer in resin systems has an acceptable biocompatibility for dentin-pulp, involving its adsorption and adhesion to hard tooth tissues.View full abstractDownload PDF (1275K) -
Linlin HAN, Akira OKAMOTO, Masaaki IWAKU1992 Volume 11 Issue 1 Pages 26-37,112
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSIn this study, enamel micro-cracks produced around composite restorations were observed on surfaces and vertical sections, using a stereomicroscope and a scanning electron microscope (SEM). The effects of various clinical factors, i.e. the curing system, the marginal form and the polishing period after filling, on the incidence of marginal enamel micro-cracks were examined. Enamel micro-cracks were observed on all of the class 1 and 5 composite restorations when the cavity had no marginal bevel and the restorations were polished immediately after filling. Enamel micro-cracks distributed approximately parallel to the cavity margin and located 0.01-0.3mm from the restored cavity margin. The occurrence of enamel micro-cracks was higher in light-cured composite resin restorations than in chemical-cured ones, for non-beveled cavities when polished 10min or 24 hours after filling. The occurrence of micro-cracks was reduced by marginal beveling and delayed polishing.View full abstractDownload PDF (5490K) -
CAD to Produce Crown Considering OcclusionHiroshi KIMURA, Taiji SOHMURA, Junzo TAKAHASHI1992 Volume 11 Issue 1 Pages 38-44,112
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSUse of a CAD program to design the shape of a crown, restoration of 6 molar was studied. Stone models of 5 to 7 molars with 6 prepared die for crown and a complete 6 crown which was applied for restoration were measured. The 6 crown data were adapted on the 6 die, and adjusted with 5 and 7 proximal teeth. The coordinates of the data of 6 were then transferred to that of the 6 die. The ends of the adapted crown data were linked with the margin of 6 die.
Further the occlusal condition with antagonistic tooth was adjusted by applying the FGP (functionally generated path) technique. FGP was recorded on bite wax and measured. Comparing FGP record and adapted crown, modulation of the occlusal surface was accomplished.View full abstractDownload PDF (4007K) -
Jee Youn KIM, Yoshifumi TAKAHASHI, Masashi KITO, Yoshiya MORIMOTO, Jir ...1992 Volume 11 Issue 1 Pages 45-58,113
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSRhodamine B, a fluorescent substance, was used as a tracer to investigate in vitro early microleakage from around amalgam restorations in machinable mica glass-ceramic after thermal stress. Five types of amalgam, i.e., low-copper spherical, low-copper lathe-cut, high-copper admixture, high-copper lathe-cut, and high-copper spherical, were examined in the present study. The results indicated that early microleakage from alloys of lathe-cut particles was lower than that from alloys of spherical particles in both low-copper and high-copper amalgam restorations. A high-copper amalgam with a mixture of lathe-cut and spherical particles tended to exhibit the lowest early microleakage.View full abstractDownload PDF (5377K) -
Fumio NISHIMURA, Hideo NAKAMURA, Hidekazu TAKAHASHI, Toshimasa TAKAMOT ...1992 Volume 11 Issue 1 Pages 59-69,113
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThis study developed a new investment for induction soldering using high frequency induction heating.
Ninety-five mass% magnesia clinker and 5 mass% dental stone were selected for the main constituents. The magnesia investment itself was scarcely affected by induction heating, so the addition of metal powders such as Fe, Ni, Co were investigated. Among these three powders, the addition of 10 mass% cobalt powder was most effective. This investment needed only 40 seconds of high frequency induction heating to go from room temperature to 900°C without preheating. Thermal expansion of this investment in a vacuum atmosphere was 1.25% at 1000°C.
Dimensional changes during induction soldering were measured using German-silver and silver solder. When the new magnesia investment containing 10 mass% Co powder was used, the dimensional change was -0.2%. This contraction was less than when a magnesia investment without metal additives was used.View full abstractDownload PDF (2369K) -
Analysis Between 4-META/MMA-TBB Resin and Bovine or Human DentinMamoru OZAKI, Masako SUZUKI, Kazuo ITOH, Sadao WAKUMOTO, Hisashi HISAM ...1992 Volume 11 Issue 1 Pages 70-76,114
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSA study of the adhesive interface between 4-MET/MMA-TBB resin and hydroxyapatite or bovine enamel was reported. The present report is a continuation of that study. The possible chemical interaction between 4-methacryloxyethyl trimellitic acid (4-MET) and bovine or human dentin was examined by laser Raman spectroscopy. A 4-MET monomer solution was prepared by evaporating two thirds of the methyl methacrylate (MMA) in a commercial dentin adhesive. The solution was then applied to a dentin surface after treating the surface with an aqueous solution of 10% citric acid containing 3% ferric chloride. A salt formed on both bovine and human dentin surfaces. This salt was formed by the process we previously reported in which 4-MET formed a salt on the hydroxyapatite and bovine enamel. No evidence was observed of chemical reaction between 4-MET and any organic component in the dentin.View full abstractDownload PDF (1149K) -
Application on the Skin of Guinea PigsKazuyuki KATSUNO, Atsufumi MANABE, Tokuji HASEGAWA, Sadao NAKAYAMA, Ka ...1992 Volume 11 Issue 1 Pages 77-82,114
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSWe studied the allergic reaction of guinea pigs to glyceryl methacrylate (GM), hydroxyethyl methacrylate (HEMA) and meso-erythritol methacrylate (EM), which are used as dentin primers. On the 18th day of the application test, when macroscopic investigation revealed an inflammatory reaction, the methacrylic acid-treated group showed marked eschar formation in comparison with the control group. In each of the dentin primer groups, a slight degree of skin redness was noted, but there were no serious symptoms. On the 25th day, the applications were resumed macroscopic inspection on the 32nd day found eschar in the methacrylic acid group only. Therefore, this experiment with dentin primers suggests a delayed allergic reaction. Local irritability test showed a more severe reaction than the application test. In this test, all experimental dentin primers and methacrylic solution promptly showed inflammation, and the chemical compound, methacrylic acid was a factor in inflammation.View full abstractDownload PDF (2105K) -
Takeshi HONDA, Tsunehisa SHIMODA, Shinichi UKON, Shuhei SUMIYOSHI1992 Volume 11 Issue 1 Pages 83-96,114
Published: June 25, 1992
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSA large and clearly visible operating area is essential for successful arthroscopic surgery of the temporomandibular joint. The keys to a successful operation are the safe and accurate positioning of a large scope and multiple cannulations, overcoming blind areas.
We developed some instruments to resolve these problems; i.e., scopes with a large diameter for high resolution, a triangulation instrument for multiple cannulations, a needle set-up jig for disk traction suture, a step cannulation system and a two-channel cannula for operating in the narrow lower joint space and a fixing jig for cannulas in the upper and lower joint space to observe the same portion of the discal tissue from both joint space during disk suturing.
From our experience in applying systematic procedures using these instruments in 37 arthroscopic surgeries, it is possible for this procedure to be done under a visual field and the surgical time considerably shortened.View full abstractDownload PDF (5727K)
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