Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials最新文献

{"title":"[Studies on the dynamic durability of dental restorative materials. Part 4. Materials evaluation of initial and fatigue specimen for composite resins by acoustic emission method].","authors":"S Kondo,&nbsp;S Okawa,&nbsp;T Hanawa,&nbsp;T Sugawara,&nbsp;M Ota","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Present study is directed towards development for a method of materials evaluation of the static and dynamic properties for dental restorative materials and nondestructive inspection of the dental restorations in oral cavity by acoustic emission (AE) method. AE characteristics and deformation-fracture behavior of hour commercial composite resins under three points bending test are examined in order to evaluate initial and fatigue specimen for conventional and microfilled composite resins. Experimental results obtained are as follows: (1) Deformation-fracture behavior of conventional and microfilled composite resins exhibits different mode, corresponding to relatively brittle and ductile fracture behavior, respectively. Therefore, the primary sources of AE for conventional and microfilled composite resins under bending test are related mainly to the nucleation and propagation of cracks and plastic deformation, respectively. (2) In conventional composite resins under bending test, the burst type AE signal of higher amplitude and shorter decay time and more many AE total counts tend to be observed. In microfilled composite resins under bending test, the burst type AE signal of lower amplitude and longer decay time and more a few total counts tend to be observed. (3) Composite resins, particularly conventional composite resins under unload and repeated bending load are indicative of different AE characteristics. Accordingly, application of AE method for composite resins offers a method to evaluate the static and dynamic strength of composite resins. (4) In conventional composite resins under bending test, as characteristic AE are observed in a few stress regions before fracture, it may be possible to monitor nondestructively the restorations in oral cavity by using AE method.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 60","pages":"315-22"},"PeriodicalIF":0.0,"publicationDate":"1981-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17999759","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":"Fracture process in tensile testing dental Ni-base casting alloys.","authors":"K Wakasa,&nbsp;M Yamaki,&nbsp;A Nakatuka,&nbsp;T Nishimura","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Early-fracture in tensile specimens was found in Ni-base casting alloys which were obtained in conventional casting condition. In 32 Ni-23 Cu-25 Mn alloy, intercrystalline fracture occurred in both early-fractured and normal ductile specimens. On the contrary, intercrystalline and innercrystalline fracture were, respectively, found in early-fractured and normal samples. As the fracture process, voids formed by stress-concentration around A-grain and brittle fracture of soft B-grain in 32 Ni-23 Cu-25 Mn alloy, while voids occurred by stress-concentration around inclusion as chromium carbide and slip deformation on the maximum shear stress plane in 84 Ni-9 Cr alloy.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 60","pages":"290-4"},"PeriodicalIF":0.0,"publicationDate":"1981-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17999754","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":"[Studies on the performance of the dental air turbine handpieces. (Part 5) Rotational performance of various kinds of dental air turbine handpieces (N = N0--CvFv gamma) (author's transl)].","authors":"H Miyairi,&nbsp;M Nagai,&nbsp;H Fukuda,&nbsp;A Muramatsu","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Making research on the rotational performance of the dental air turbine handpieces widely used for dental cutting instruments, we investigated with the relation between rotational speed and load on many kinds of dental handpieces used for clinical divisions and with the applications of the theoretical equations to have be shown in the previous report. And then we have the investigation on these properties. Dental handpieces to measured with these properties were classified the four types, standard types, torque type, miniature type and air bearing type. And we applied the experimental equations to these experimental values and determined the rotational coefficients, gamma and Cv. The rotational speed N and normal force Fv, which occurred the maximum work of air turbine handpieces, were calculated with our analysis and then these values of N and Fv were compared with the experimental results. These results, that is, experimental and calculated values have a good agreement and the development of the theoretical approach is useful for the estimation of the rotational performance. And we examined the possibility of rotational performance's estimation with the process of simple experiment on these air turbine handpieces.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 60","pages":"262-70"},"PeriodicalIF":0.0,"publicationDate":"1981-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18084975","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":"Corrosion behaviour and heat treatment in low-melting Ni-Cu-Mn alloy.","authors":"K Wakasa,&nbsp;M Yamaki","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The appropriate procedure to improve corrosive property of B-grain in Ni-Cu-Mn casting alloy was to do the heat treatment at 350 degrees C for 6 hrs, because heavy corrosive behaviour was observed for only B-grain in dendritic A-grain, disk-like B-grain and very large C-grain. Then, new grain with corrosion-resistance appeared at previous location of B-grain.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 60","pages":"295-8"},"PeriodicalIF":0.0,"publicationDate":"1981-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17999757","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":"[Solubility of metal components into tissue culture medium from dental amalgams (author's transl)].","authors":"H Kawahara,&nbsp;T Yamada,&nbsp;M Nakamura,&nbsp;T Tomoda,&nbsp;H Kobayashi,&nbsp;A Saijo,&nbsp;Y Kawata,&nbsp;S Hikari","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Solubility of metal components into tissue culture medium, YLH, from various dental amalgams including high copper, conventional and copper amalgam was measured with atomic absorption spectrometry. The results obtained were as follows.: 1. Mercury solubility was found much in all the dental amalgams after one day extraction. This was followed by gradual increase in solubility in the high copper amalgams until after seven days. On the otherhand, initial high solubility was maintained in conventional and copper amalgams through the whole experimental period. 2. Higher solubility of silver and copper was recorded in the high copper amalgams. 3. Zinc was only found in Dispersalloy and copper amalgam. 4. Tin was unable to be measured in all the amalgams examined. It was considered that the present results could shed a light on the mechanism for cytotoxicity yielding of the dental amalgams.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 60","pages":"285-9"},"PeriodicalIF":0.0,"publicationDate":"1981-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17999926","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":"[Determination of hydrophobic parameters (log PHPLC) for methacrylates, initiators and miscellaneous compounds used in dentistry by high-performance liquid chromatography (HPLC) (author's transl)].","authors":"S Fujisawa,&nbsp;E Masuhara","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The use of partition coefficients Poct obtained from an n-octanol-water partitioning system has become a standard method for modelling biological membranes and thereby quantifying the hydrophobicity of a given compound as log Poct = log Coct--log Cwater. However, there is no convenient method available to determine the log Poct value accurately. The conventional flask-shaking method is a laborious and time consuming procedure, often complicated by instability in aqueous media, impurities and the tendency for the compound to dissociate. There have been recently attempts using HPLC to determine the hydrophobicity of organic compound. The retention behaviour of about fifty organic compounds in HPLC systems have been examined. Using methanol-water as the mobile phase, a linear relationship between the volume fraction of organic modifier and the logarithm of the capacity factor (log K') over limited range was obtained for standards. However, unfortunately, the correlation between log Kw obtained from the extrapolated K' values with pure water as eluent and log Poct values was not good (r = 0.83). Using this octadecylsilyl column with the mobile phase (methanol: water = 70:30), standards fall on the three straight lines with good correlations (r = 0.99) between the log Poct and log K' values.: one for benzenes and aliphatic compounds, the second for phenols, anilines and hydrogenacceptor benzene derivatives and the third for benzoic acids, respectively. The PHPLC values of methacrylates, initiators and miscellaneous compounds which are widely in dentistry were determined using these three regression lines.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 60","pages":"277-84"},"PeriodicalIF":0.0,"publicationDate":"1981-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17999925","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":"[Studies of dental methacrylic resin. (Part 8) Flexural and impact adhesive strength of self-curing methacrylic resin to cross-linked polymethyl methacrylate resins (author's transl)].","authors":"T Hirasawa,&nbsp;S Hirabayashi,&nbsp;I Harashima","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Heat-curing methacylic resins cross-linked with three kinds of dimethacrylates, i.e. EDMA, tri-EDMA and nona-EDMA, were prepared, and the flexural and the impact adhesive strength of the dough moulding type and the pour type self-curing methacrylic resins to them were examined. The results obtained were as follows. (1) The flexural and the impact adhesive strength of the pour type self-curing resin were higher and more stable than those of the dough moulding type one. (2) The flexural and the impact adhesive strength of self-curing resins to cross-linked adherent resins rised in order of nona-EDMA greater than tri-EDMA greater than EDMA in the range of higher concentration of cross-linking agents. This tendency was marked for the pour type resin. (3) When the dough moulding type resin was used as adhesive resin, to adherent resin cross-linked with EDMA or tri-EDMA which had relatively short chain, the respective adhesive strength of that decreased with increasing the concentration of cross-linking agent. While, to adherent resin cross-linked with nona-EDMA, which had relatively long and more flexible chain, the respective adhesive strength of the dough moulding type resin increased with increasing the concentration of cross-linking agent. (4) When the pour type resin was used as adhesive resin, to adherent resin cross-linked with EDMA or tri-EDMA, the respective adhesive strength of that showed the maximum at the concentration near 2 to 5 mole% and decreased with increasing the concentration. While, to adherent resin cross-linked with nona-EDMA, the flexural adhesive strength of the pour type resin was approximately constant without the effect of the concentration, but the impact adhesive strength of that increased with increasing the concentration. (5) The flexural adhesive strength of the dough moulding and the pour type resin under the wet condition decreased about 30 to 60% compared with under the dry condition, but the percentage of the falling for the impact adhesive strength was about 15 to 30% and relatively small. (6) The flexural adhesive strength showed a similar adhesive tendency to the tensile adhesive strength, but the impact adhesive strength showed a different adhesive tendency from those.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 60","pages":"299-305"},"PeriodicalIF":0.0,"publicationDate":"1981-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17999758","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":"[Dimensional stabilities of microfilled composite resins (author's transl)].","authors":"T Hirasawa,&nbsp;S Hirano,&nbsp;S Hirabayashi,&nbsp;I Harashima,&nbsp;I Nasu,&nbsp;M Aizawa","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Thermal expansion, expansion by water sorption, water sorption and solubility to water, which will influence to the marginal closure of cavities restored, were evaluated in seven microfilled composite resins, comparing with two conventional composite resins. The following results were obtained. 1) Coefficients of linear thermal expansion of microfilled composite resins were 41 to 84 x 10(-6)/degrees C in the dry condition and 57 to 93 x 10(-6)/degrees C in the wet condition. Those values were about 2 to 3 times those of conventional composite resin, and about 6 to 8 times that of teeth. 2) Linear expansion by water sorption was highly correlated to water sorption. Microfilled composite resins had higher values of liner expansion by water sorption compared to conventional ones. 3) Generally, water sorption of microfilled composite resins were higher than those of conventional ones. After 7 days, they were about 0.4 to 1.9 mg/cm2. Values of microfilled ones which contained larger amount of filler or was composed of more hydrophobic matrix resin, however, were lower than others. 4) Solubilities to water of microfilled composite resins also were higher than those of conventional ones. Particularly, microfilled ones which were used organic composite filler and UDMA monomer as base material and photopolymerized had relatively higher values.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 59","pages":"196-201"},"PeriodicalIF":0.0,"publicationDate":"1981-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17995285","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 inorganic material activated with polyacrylic acid - heat treatment property of wollastonite -].","authors":"M Takahashi,&nbsp;T Nihei,&nbsp;K Kato","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>We investigated Wollastonite property by means of heat treatment in order to indicate the Wollastonite activation with Polyacrylic acid. Wollastonite was transformed into alpha-Calcium meta silicate when its temperature exceeded 1 200 degree C, and also we found that the activation with Polyacrylic acid revealed the hardening property via higher heat treatment before and behind of the transformation point.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 58","pages":"109-13"},"PeriodicalIF":0.0,"publicationDate":"1981-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17995614","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":"[Studies on sintering of dental porcelain. (Part 1) Binary system sintering of alumina and low fusing frit (author's transl)].","authors":"N Kuwayama,&nbsp;M Kon","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Dental porcelains were made from frit and glass powder with electro fused alumina powder addition in the range from 20 to 60 wt% using sintering method at the temperature from 500 degree C to 1 000 degree C, and the effects of alumina content and firing temperature on firing processes of sintered composite were investigated. Shrinkage curves of the powder compacts varied with kind of frit and content of alumina. Particulary, powder compact with alumina addition in the range from 50 to 55% was found to have a remarkable influence for extention of firing temperature range. The densification of the powder compacts was considered to be accelerated by the dissolution of a small a mount of alumina particle into the frit and glass above 900 degree C. Expansion coefficient value of sintered composite of alumina and Pyrex glass powder gradually increased with increase of alumina content. Inversely, expansion coefficient of soda-lime-silica glass showed the minimum value at 40 wt% alumina content and then had a tendency of slight increases with increase of alumina content.</p>","PeriodicalId":76541,"journal":{"name":"Shika rikogaku zasshi. Journal of the Japan Society for Dental Apparatus and Materials","volume":"22 58","pages":"101-8"},"PeriodicalIF":0.0,"publicationDate":"1981-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17995613","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}