Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices最新文献

{"title":"[Study on visible-light curing soft resins consisting of fluoropolymers. 2. Effect of fluoroalkyl alpha-fluoroacrylate monomers].","authors":"Y Ohe,&nbsp;Y Kadoma,&nbsp;Y Imai","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>New experimental visible-light cured soft resins were prepared by combining a vinylidene fluoride/hexafluoropropylene copolymer (2-6 F), or a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer (2-4-6 F) with 2,2,3,3-tetrafluoropropyl alpha-fluoroacrylate (4 FFA), 2,2,3,3,3-pentafluoropropyl alpha-fluoroacrylate (5 FFA), 2,2,3,3,4,4,5,5-octafluoropentyl alpha-fluoroacrylate (8 FFA), or 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl alpha-fluoracrylate (12 FFA). Some properties of the resins prepared were measured to determine whether they would be candidate materials for the soft denture liner. Water contact angles increased with the increase in the number of fluorine atoms contained in the monomers: 85-90 degrees in 4 FFA, 90-93 degrees in 8 FFA, and 92-93 degrees in 12 FFA. Softer resins were obtained with 2-4-6 F, especially by the combination with 8 FFA giving the softest resin with a hardness of 43-46 (JIS A). Water sorption after 10 weeks was considerably low: 0.4-2%: 0.4-0.9% in 4 FFA/2-6 F and about 2% in 8 FFA/2-4-6 F. Solubility was 0.2-0.4% in the resins with 4 FFA and 1.0-1.4% with 8 FFA or 12 FFA. Amount of residual monomer was low, and the maximum was 0.4% in the resin with 12 FFA. Thus hardness and water sorption of the resins prepared were superior to those of the commercial soft materials.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"647-53"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13288920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[A study on the improvement of denture base resin. Epoxy dimethacrylate-polybutadiene dimethacrylate-MMA monomers as the liquid of denture base resin].","authors":"H Teshima,&nbsp;S Matsukawa","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The dimethacrylates, EpDMA and BdDMA, which have a bisphenol type epoxy chain and butadiene chain in their main chains, respectively, were synthesized. The properties of the terpolymer composed of EpDMA, BdDMA and MMA monomers were examined. The monomer mixture of EpDMA, BdDMA and MMA was used as the liquid of denture base resin, and the properties of the cured resin were examined. The polymerization shrinkage of the terpolymer of EpDMA-BdDMA-MMA decreased with the increase in the EpDMA concentration in the cured resin, and the transverse strength and the elastic modulus were greatest at the BdDMA concentration of 0.3-1 vol%. The denture base resin produced using a monomer mixture as the liquid, the transverse strength and the impact strength showed the highest values of about 110 MPa and 14 KJ/m2, respectively, at the liquid composition of 10 vol% EpDMA, 1 vol% BdDMA and 89 vol% MMA.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"509-19"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[A study on disintegration of posterior composite resins caused by long-term water immersion].","authors":"K Fujii,&nbsp;K Arai","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The purpose of this study is to clarify a cause of disintegration for posterior composite resins by long-term immersion in distilled water during the 3-year period. Three kinds of posterior composite resins [Bellfirm P (BP), Clearfil Posterior (CP) and Micro Jar (MJ)] and one conventional anterior composite resin [Clearfil FII (FII)] were prepared as to specimens with 20 mm diameter, and 1 mm in thickness. These specimens were immersed in distilled water at 37 +/- 1 degree C for 3 years. These specimens were observed by scanning electron microscope (SEM). The residuces in distilled water were analyzed by X-ray microdiffractometry, infrared (IR) and nuclear magnetic resonance (NMR) spectrometers. One posterior composite resin (microparticle filled resin) was eluted in water more than the other posterior and anterior composite resins with conventional fillers. In SEM observations, many air bubbles were found inside all sections of the four composite resins, because of all mixing type composite resins. The subsurface layer of all four composite resins showed signs of disintegration, but the center layer of the specimens was not disintegrated. Three cured composite resins except MJ had crystalline X-ray diffraction patterns before water immersion, but the cured MJ alone was amorphous. These peaks of crystals showed fillers of these composite resins respectively. X-ray diffraction patterns of the dissolved substances for three composite resins except BP were also crystalline, but the peaks of the crystals except CP were different from the peaks of the fillers respectively. In IR and 1H-NMR spectra of dissolved substances, an unreacted monomer could be detected in one posterior composite resin (BP), but not in the other composite resins. In 1H-NMR spectra of dissolved substances, new signals not found originally were observed in all four composite resins. Therefore, the progress of disintegration was demonstrated clearly. The dissolved substances of all four composite resins were shown as the disintegrated substances between resin matrixes and silane coupling agents. It is suggested that the disintegration of these composite resins by long-term water immersion is derived from hydrolysis.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"561-76"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Three-dimensional shape measurement of teeth. (6) Measurement of tooth model by tilting method by means of the double sensor laser displacement meter, and the simulation of occlusion].","authors":"H Kimura,&nbsp;T Sohmura,&nbsp;T Watanabe","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>To measure the three-dimensional shape of the undercut portion of a molar model tooth, the tilting method was used. The measuring system was composed of a laser displacement meter with double sensor and a computer controlled tooth model scanning machine (CAMM-3). A model tooth was tilted on the gonio stage with +/- 20 degrees and measured divisionally, and a couple of data were connected by the TILCOMPO program. The undercut portions from the survey line to the tooth neck were measured and drawn by CG. By this tilting method, the whole shape of tooth including the undercut portion could be measured, and these data will be available for the production of the data base for CAD of prosthesis. The marginal line on the crown abutment measured previously was searched. Initially, the difference in the inclination dz/dx between the data before and behind was calculated, and the gingival line was extracted by limiting its value. Then, also by limiting the difference value, the margin located above the gingival line was determined. Thus the marginal line in contact with the inner and outer crown and a significantly important point for the production of crown by the CAD/CAM technique could be determined around the crown abutment. Another elementary attempt to simulate the occlusion by using the data of teeth models measured on the articulator was carried out. The maxillary and mandibular teeth were set on the articulator and the maxillary teeth turned over. The shapes of the 5-7 upper and lower molar were measured. The two data were connected and occluded by the \"OCCLUS\" program.(ABSTRACT TRUNCATED AT 250 WORDS)</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"679-86"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13288923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Study on visible-light curing soft resins consisting of fluoropolymers. (3) Application of low molecular weight fluoropolymer].","authors":"Y Ohe,&nbsp;Y Kadoma,&nbsp;Y Imai","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>New experimental visible-light cured soft resins were prepared by combining a low molecular weight vinylidene fluoride/hexafluoropropylene copolymer (2-6 FL), or vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer (2-4-6 FL) with 2,2,3,3-tetrafluoropropyl alpha-fluoroacrylate (4 FFA), or 2,2,3,3,4,4,5,5-octafluoropentyl alpha-fluoroacrylate (8 FFA). Some properties of the resins prepared were measured to determine whether they would be candidate material for a soft denture liner. Water contact angle was 90-92 degrees with 4 FFA, and 90-94 degrees with 8 FFA. The resins combined with 2-4-6 FL were sufficiently soft: 42-46 (JIS A hardness) in 4 FFA, and 33-39 in 8 FFA. Generally the hardness decreased by 5-10 with the use of a low molecular weight of fluoropolymer. Water sorption after 10 weeks was 0.8-1.2% in 2-6 FL/4 FFA, 1.3-1.7% in 2-6 FL/8 FFA, about 1% in 2-4-6 FL/4 FFA, and about 2% in 2-4-6 FL and 8 FFA. Solubility was 0.4-0.5% in 2-6 FL/4 FFA, 0.3-0.4% in 2-4-6 FL/4 FFA, 1.5-1.9% in 2-6 FL/8 FFA, and 1.1-1.5% in 2-4-6 FL/8 FFA. Amount of residual monomer was very low, and the maximum was 0.1%. Tensile strength of the resins was reduced to 40-70% of that of the similar resins obtained in the previous study. Thus softer resins could be prepared by using lower molecular weight fluoropolymers.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"654-8"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13288921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Dissolution of silver and copper from Ag-Cu binary alloys under dynamic conditions].","authors":"S Takeda,&nbsp;Y Sano,&nbsp;T Takimoto,&nbsp;N Tsutsumi,&nbsp;M Nakamura","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Ag-Cu binary alloys containing 5-30% copper were subjected to dynamic extraction at 200 rpm and 37 degrees C to simulate the functional movement in the oral environment. Extraction was carried out in Eagle's minimum essential medium every two weeks for 18 weeks. The corrosion products were examined by the separation of extracts with a 0.22 micron filter. Significant dissolution of copper occurred with increasing copper content, but the increase in silver dissolution was slight. The amount of copper in the filtrate was the same as that in the extract, but no silver was detected in the filtrate. Therefore, dynamic extraction accelerated the dissolution of copper from the Ag-Cu binary alloys and thus lowered the corrosion resistance.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"555-60"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Cytotoxic effects of restorative materials on early passage cultured cells derived from human gingiva (in vitro)].","authors":"N Yamagata,&nbsp;H Oshima","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>This study evaluated the cytotoxic effects of three common restorative materials on early passage cultured cells derived from human gingiva (HG cells). Other early passage cultured cells derived from human dental pulp tissues (HP cells) and L cells established obtained from mouse subcutaneous tissues, were also examined. Cytotoxicity was assessed according to the uptake of neutral red and dye exclusion with nigrosin. The cytotoxicity was in the order of glass ionomer cement (highest), light cured composite resin and dental amalgam. HG cells were the least sensitive to the materials tested. Both filtration of extracts and addition of serum into the extract affected the cytotoxicity. Glass ionomer cement increased the acidity of the extract, but the two other materials did not. Dissolution of metal ions, aluminium, tin, copper, mercury and zinc occurred from the materials. The extract of the composite resin had a different absorbance. This study disclosed differences in the cellular reaction to the restorative materials. Thus, utilization of early passage cultured cells is necessary for biological evaluation of the dental materials in vitro.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"541-54"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Shrinkage stress developed by polymerization of composite resin].","authors":"K Komatsu","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The effects of the shrinkage stress on the various cavity forms, were examined. The shrinkage stress was obtained from the displacement of the brass mold developed by polymerization of the composite resin. The shrinkage stress developed in the cavity wall, was analyzed by the finite element method, and the crack of the cylindrical silica tube filled with composite resin, was observed. The shrinkage stress 30 minutes after mixing the composite resin was reduced with the increase in the marginal angle as well as the diameter or the depth of cavity. Preparation of the bevel at the cavity margin reduced the shrinkage stress. In the case of reverse bevel, reduction of the stress was not observed within 24 hours, but in the other cases, the stress immediately decreased after hardening. The analysis by the finite element method reveoled the maximum stress at the margin, with less stress for the round, flat and reverse bevel in this order. For the observation of the cylindrical silica tube filled with composite resin, the crack was observed in the cylindrical silica tubes prepared round, flat or without bevel, it was not observed in the tube prepared reverse bevel that the crack was developed in this tube and composite resin was detached from this tube within 24 hours.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"520-40"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Quantitative evaluation by measuring affected area for cytotoxicity of dental materials].","authors":"M Kaga,&nbsp;Y Ito,&nbsp;T Okabe,&nbsp;H Oguchi,&nbsp;M Ota","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The agar overlay method was modified and employed in this study to quantitatively evaluate the cytotoxicity of dental materials. The area of fibroblasts affected by the release of toxic substances from tested materials was determined with an image analysis system in order to compare the relative cytotoxicity of amalgams and composite resins. The cytotoxicity of amalgams decreased by 50% or more with aging time. Zinc appeared to be the major contributor to the cytotoxicity of amalgams. The cytotoxicity of chemically cured composite resins was also reduced with hardening time. However, even after 24 hours, the cytotoxicity of all chemically cured composite resins was still apparent. The cytotoxicity of light cured composite resins was dramatically reduced after illumination with the light source. The cytotoxicity of both amalgams and composite resins was strongly dependent upon their hardening process, since aging and curing produced a more stable material which was less likely to release toxic substances into the culture medium. The technique developed in the present study for measuring the area of affected cells to quantitatively evaluate the cytotoxicity of dental materials is simple and reproducible.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"591-9"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Guide to a new database system of literatures on dental materials and devices. (2)].","authors":"Y Araki","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>A new database system of literatures on dental materials and devices was developed by the Committee for the Database, the Japanese Society for Dental Materials and Devices, with the cooperation of the members. The procedure for the information retrieval using on-line system (N 1 network system) was shown with examples.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":"9 4","pages":"687-94"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13288924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}