Molecular composites, composed of polymethylmethacrylate (PMMA) resin as matrix reinforced with polyaramides as a rigid core molecule have been developed to produce a denture base polymer with improved dental material properties. N-substituted polyaramides were prepared via metalation using sodium methylsulfinylcarbanion, followed by the reaction with corresponding octyl bromide and/or stearyl bromide in dimethyl sulfoxide. In these molecular composite resins (called Oct-PPTA-PMMA and Ste-PPTA-PMMA short) compounding 3 wt% of N-octylated-PPTA (Oct-PPTA) and/or N-stearylated-PPTA (Ste-PPTA) to PMMA, their dental material properties were in the order of Oct-PPTA-PMMA greater than Ste-PPTA-PMMA greater than or equal to PMMA. Their polymer properties were analyzed to molecular level, using nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric (TG) analysis and dynamic mechanical thermal analysis (DMTA). The molecular motion of the methyl group of Oct-PPTA proved to be constrained for the rigid main chain by T1 (inversion recovery method) NMR spectra in CDCl3 while that of Ste-PPTA was not affected. The thermal properties of the composites were in the order of Oct-PPTA-PMMA greater than Ste-PPTA-PMMA greater than PMMA by TG analysis, and the dynamic storage modulus values were Oct-PPTA-PMMA greater than Ste-PPTA-PMMA greater than PMMA in the region from rubbery state to viscous flow state by DMTA.
{"title":"[On mechanical behavior of molecular composite resins reinforced with polyaramides. Molecular motion of Oct-PPTA and Ste-PPTA and thermal properties and dynamic viscoelasticity of Oct-PPTA-PMMA and Ste-PPTA-PMMA].","authors":"S Higuchi","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Molecular composites, composed of polymethylmethacrylate (PMMA) resin as matrix reinforced with polyaramides as a rigid core molecule have been developed to produce a denture base polymer with improved dental material properties. N-substituted polyaramides were prepared via metalation using sodium methylsulfinylcarbanion, followed by the reaction with corresponding octyl bromide and/or stearyl bromide in dimethyl sulfoxide. In these molecular composite resins (called Oct-PPTA-PMMA and Ste-PPTA-PMMA short) compounding 3 wt% of N-octylated-PPTA (Oct-PPTA) and/or N-stearylated-PPTA (Ste-PPTA) to PMMA, their dental material properties were in the order of Oct-PPTA-PMMA greater than Ste-PPTA-PMMA greater than or equal to PMMA. Their polymer properties were analyzed to molecular level, using nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric (TG) analysis and dynamic mechanical thermal analysis (DMTA). The molecular motion of the methyl group of Oct-PPTA proved to be constrained for the rigid main chain by T1 (inversion recovery method) NMR spectra in CDCl3 while that of Ste-PPTA was not affected. The thermal properties of the composites were in the order of Oct-PPTA-PMMA greater than Ste-PPTA-PMMA greater than PMMA by TG analysis, and the dynamic storage modulus values were Oct-PPTA-PMMA greater than Ste-PPTA-PMMA greater than PMMA in the region from rubbery state to viscous flow state by DMTA.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289827","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}
The influence of metal elements in three Pd alloys on the bonding to porcelain was examined. The high-temperature oxidation behavior of metal elements in alloys, structure and morphology of oxidation zones on the alloy surface and the appearance of bonding between alloy and fused porcelain at the interface were studied by ESCA and EPMA. From ESCA analysis, metal oxides such as PdO, SnO2, In2O3, CuO or Cu2O, Sb2O3 or Sb2O5 were formed on the surface of the alloy after degassing (preheating) and heating following casting. The amount of metal elements concentrated on the alloy surface was measured by their characteristic X-rays using area analysis of EPMA under the technical conditions of A) Acc. voltage 10 kV, Abs. current 40 nA, and B) Acc. voltage 20 kV, Abs. current 10 nA. Consequently, the amount of additive metal elements concentrated on the alloy surface which was detected in condition A) was larger than that detected in condition B). However, the amount of main element (Pd) concentrated on the alloy surface which was detected in condition A) was smaller than that detected in condition B). From the EPMA observation of the interface between alloy and fused porcelain, cross-section of alloys showed that the additive metal elements were oxidized in the alloy matrix, forming an internal oxide layer or particles. The structure and morphology of oxidation zones showed a significant difference between degassed and not-degassed alloys. Cross-sections inclined approximately 5 degrees 43' to the fusing boundary were also analyzed to enlarge the oxidation zones. This analytical technique effectively revealed the structure and morphology of oxidation zones. In conclusion, not only additive metal elements but also the main element at the surface of alloys play important roles on the bonding to porcelain. Degassing of the alloy was considered to an essential procedure to obtain the adequate bonding to porcelain.
考察了三种钯合金中金属元素对其与瓷结合的影响。采用ESCA和EPMA研究了合金中金属元素的高温氧化行为、合金表面氧化带的组织和形貌以及合金与电熔瓷界面的结合情况。ESCA分析表明,铸后除气(预热)和加热后在合金表面形成了PdO、SnO2、In2O3、CuO或Cu2O、Sb2O3或Sb2O5等金属氧化物。在A) Acc的工艺条件下,用EPMA面积分析法测定合金表面金属元素的特征x射线量。电压10kv, ab,电流40na, B) Acc。电压20kv, abs,电流10na。因此,在A)条件下合金表面的金属添加元素浓度大于B)条件下合金表面的金属添加元素浓度,而在A)条件下合金表面的主元素(Pd)浓度小于B)条件下合金表面的主元素(Pd)浓度。合金截面分析表明,合金基体中添加的金属元素被氧化,形成内部氧化层或氧化颗粒。脱气合金与未脱气合金氧化区的组织和形貌有显著差异。向熔合边界倾斜约5°43′的截面也会扩大氧化区。该分析技术有效地揭示了氧化带的结构和形态。综上所述,除了添加金属元素外,合金表面的主元素对陶瓷的结合也起着重要的作用。合金的脱气被认为是获得与瓷充分结合的必要步骤。
{"title":"[Influence of metal elements in Pd alloys on the bonding to porcelain].","authors":"Y Kurisaki, K Nagayama","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The influence of metal elements in three Pd alloys on the bonding to porcelain was examined. The high-temperature oxidation behavior of metal elements in alloys, structure and morphology of oxidation zones on the alloy surface and the appearance of bonding between alloy and fused porcelain at the interface were studied by ESCA and EPMA. From ESCA analysis, metal oxides such as PdO, SnO2, In2O3, CuO or Cu2O, Sb2O3 or Sb2O5 were formed on the surface of the alloy after degassing (preheating) and heating following casting. The amount of metal elements concentrated on the alloy surface was measured by their characteristic X-rays using area analysis of EPMA under the technical conditions of A) Acc. voltage 10 kV, Abs. current 40 nA, and B) Acc. voltage 20 kV, Abs. current 10 nA. Consequently, the amount of additive metal elements concentrated on the alloy surface which was detected in condition A) was larger than that detected in condition B). However, the amount of main element (Pd) concentrated on the alloy surface which was detected in condition A) was smaller than that detected in condition B). From the EPMA observation of the interface between alloy and fused porcelain, cross-section of alloys showed that the additive metal elements were oxidized in the alloy matrix, forming an internal oxide layer or particles. The structure and morphology of oxidation zones showed a significant difference between degassed and not-degassed alloys. Cross-sections inclined approximately 5 degrees 43' to the fusing boundary were also analyzed to enlarge the oxidation zones. This analytical technique effectively revealed the structure and morphology of oxidation zones. In conclusion, not only additive metal elements but also the main element at the surface of alloys play important roles on the bonding to porcelain. Degassing of the alloy was considered to an essential procedure to obtain the adequate bonding to porcelain.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289742","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}
An injector and FRP denture flask were developed for injection molding and the fit of the denture base constructed with this injection molding system was evaluated. In addition, the flow and pressure of the dough, that is polymer-monomer mixture, in the mold space were investigated. The monomer of 10 mg/cm2 in the dough vaporized during the 5 minutes it took for the flash to be removed. When pressure of more than 55 kgf/cm2 was exerted to the dough, the dough was completely packed in the mold space. Fastening of the sprue with a bolt within 2 minutes after injection of the dough made the pressure of the dough increase to about 30 kgf/cm2. The dough in the mold space was maintained at a pressure of above 20 kgf/cm2 for microwave heating time. The adaptability of the resin base denture constructed with a combination of injection molding and microwave polymerization was 2 or 3 times greater than that of the denture constructed with microwave heating from the tissue side of the denture base.
{"title":"[Application of microwave for dental technique. 5. Injection molding system for resin base denture].","authors":"H Kimura, F Teraoka, M Sugita","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>An injector and FRP denture flask were developed for injection molding and the fit of the denture base constructed with this injection molding system was evaluated. In addition, the flow and pressure of the dough, that is polymer-monomer mixture, in the mold space were investigated. The monomer of 10 mg/cm2 in the dough vaporized during the 5 minutes it took for the flash to be removed. When pressure of more than 55 kgf/cm2 was exerted to the dough, the dough was completely packed in the mold space. Fastening of the sprue with a bolt within 2 minutes after injection of the dough made the pressure of the dough increase to about 30 kgf/cm2. The dough in the mold space was maintained at a pressure of above 20 kgf/cm2 for microwave heating time. The adaptability of the resin base denture constructed with a combination of injection molding and microwave polymerization was 2 or 3 times greater than that of the denture constructed with microwave heating from the tissue side of the denture base.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289747","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}
Methyl methacrylate (MMA)-p-styrene sulfonic acid copolymer (MS) was prepared and its adhesion to ground tooth substrates was evaluated. MS is crosslinked with Ca2+ supplied by hydroxyapatite in the smeared layer on the ground enamel and dentin, and sticks to their surface. The adhesion mechanism of MS is quite different from that of interpenetration and polymerization of monomers. The bonding strength of MMA-TBB resin to the tooth treated with an aqueous solution of MS was 11-12 MPa but that of MMA-BPO.DMPT resin was only 2.5 M Pa. Free sulfonic acids remaining in the immobilized MS disturbed the initiation of polymerization in MMA-BPO.DMPT resin. A photocurable liner, triethylene glycol dimethacrylate (TEGDMA) activated by d,l-comphorquinone (CQ), N-phenylglycine (NPG), which was polymerized in an acidic condition by irradiation, was chosen to obtain a high bond strength to the cross-linked MS on the tooth. The bond strength of TEGDMA-CQ.NPG on the tooth treated with an aqueous mixture of 10 wt% MS 7 (MMA: 70 mol%, p-styrene sulfonic acid: 30 mol%) and FeCl3 ([Fe3+]/[SO3-] = 0.28) was 10-11 MPa. The observation of the fractured surface after the tensile test and interface between precipitated MS and tooth indicated that the liner did not interpenetrate into the dentin through the immobilized MS on the tooth. These results indicated that the polymer reaction of MS with Ca2+ was important in the adhesion. In conclusion, MS is a reactive polyelectrolyte which adheres well to tooth substrates and prevents pulp irritation by hindering the penetration of the monomer.
{"title":"[A novel reactive polymer bonding composite resin to ground tooth substrates].","authors":"T Kinoshita","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Methyl methacrylate (MMA)-p-styrene sulfonic acid copolymer (MS) was prepared and its adhesion to ground tooth substrates was evaluated. MS is crosslinked with Ca2+ supplied by hydroxyapatite in the smeared layer on the ground enamel and dentin, and sticks to their surface. The adhesion mechanism of MS is quite different from that of interpenetration and polymerization of monomers. The bonding strength of MMA-TBB resin to the tooth treated with an aqueous solution of MS was 11-12 MPa but that of MMA-BPO.DMPT resin was only 2.5 M Pa. Free sulfonic acids remaining in the immobilized MS disturbed the initiation of polymerization in MMA-BPO.DMPT resin. A photocurable liner, triethylene glycol dimethacrylate (TEGDMA) activated by d,l-comphorquinone (CQ), N-phenylglycine (NPG), which was polymerized in an acidic condition by irradiation, was chosen to obtain a high bond strength to the cross-linked MS on the tooth. The bond strength of TEGDMA-CQ.NPG on the tooth treated with an aqueous mixture of 10 wt% MS 7 (MMA: 70 mol%, p-styrene sulfonic acid: 30 mol%) and FeCl3 ([Fe3+]/[SO3-] = 0.28) was 10-11 MPa. The observation of the fractured surface after the tensile test and interface between precipitated MS and tooth indicated that the liner did not interpenetrate into the dentin through the immobilized MS on the tooth. These results indicated that the polymer reaction of MS with Ca2+ was important in the adhesion. In conclusion, MS is a reactive polyelectrolyte which adheres well to tooth substrates and prevents pulp irritation by hindering the penetration of the monomer.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289749","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}
O Miyakawa, K Watanabe, S Okawa, S Nakano, N Shiokawa, M Kobayashi, H Tamura
Cast titanium was ground with commercial vitrified wheels made of alumina abrasives, and their grinding performance was investigated. For cutting, the appropriate circumferential speed of the alumina wheels was about 700 m/min. A speed lower or higher than this yielded unfavorable grinding results, which were attributed to wheel loading or chemical attrition of the abrasive, respectively. The hard wheel made of the A abrasive was suitable for grinding of titanium, and moreover, the wheel of the WA abrasive was more suitable than that made of the A abrasive. Generally, the cutting rate of the alumina wheels was inferior to that of the silicon carbide ones investigated previously. Depression of the wheel against the work yielded unfavorable grinding results; the manner in which the wheel was moved over the work during grinding was very important, compared with the silicon carbide wheels. Although the wheel was moved over the work, the high circumferential speed of the wheel resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn. The grinding burn layer mainly consisted of a few microns-thick titanium oxide.
{"title":"[Grinding of titanium. 2. Commercial vitrified wheels made of alumina abrasives].","authors":"O Miyakawa, K Watanabe, S Okawa, S Nakano, N Shiokawa, M Kobayashi, H Tamura","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Cast titanium was ground with commercial vitrified wheels made of alumina abrasives, and their grinding performance was investigated. For cutting, the appropriate circumferential speed of the alumina wheels was about 700 m/min. A speed lower or higher than this yielded unfavorable grinding results, which were attributed to wheel loading or chemical attrition of the abrasive, respectively. The hard wheel made of the A abrasive was suitable for grinding of titanium, and moreover, the wheel of the WA abrasive was more suitable than that made of the A abrasive. Generally, the cutting rate of the alumina wheels was inferior to that of the silicon carbide ones investigated previously. Depression of the wheel against the work yielded unfavorable grinding results; the manner in which the wheel was moved over the work during grinding was very important, compared with the silicon carbide wheels. Although the wheel was moved over the work, the high circumferential speed of the wheel resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn. The grinding burn layer mainly consisted of a few microns-thick titanium oxide.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289744","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}
The factors that influence the change of the transmittance of light-cured composite resins during polymerization were examined. Six experimental composite resins such as used organic composite filler and fourteen commercial composite resins were investigated using the experimental device for measurement of the transmittance. The transmittance of the experimental composite resins were from 25 to 73%. The transmittance of the experimental composite resins changed with time; a group with increasing transmittance (G1), a group giving a maximum transmittance (G2), and a group with decreasing transmittance (G3). These changes of transmittance were influenced by the difference in the refractive indices between matrix resin and filler, but the refractive index that indicated a maximum transmittance of matrix resin during polymerization could not be observed when the refractive index of the matrix resin and filler was same. The light transmitted through the commercial composite resins was less than half of the irradiation light. This change of transmittance could also be classified into the three groups mentioned above. The commercial composite resins belonged to the group with increasing transmittance (G1).
{"title":"[Transmittance of light-cured composite resins. 1. Measurement of transmittance with time].","authors":"K Komatsu, K Nemoto, K Horie","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The factors that influence the change of the transmittance of light-cured composite resins during polymerization were examined. Six experimental composite resins such as used organic composite filler and fourteen commercial composite resins were investigated using the experimental device for measurement of the transmittance. The transmittance of the experimental composite resins were from 25 to 73%. The transmittance of the experimental composite resins changed with time; a group with increasing transmittance (G1), a group giving a maximum transmittance (G2), and a group with decreasing transmittance (G3). These changes of transmittance were influenced by the difference in the refractive indices between matrix resin and filler, but the refractive index that indicated a maximum transmittance of matrix resin during polymerization could not be observed when the refractive index of the matrix resin and filler was same. The light transmitted through the commercial composite resins was less than half of the irradiation light. This change of transmittance could also be classified into the three groups mentioned above. The commercial composite resins belonged to the group with increasing transmittance (G1).</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289828","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}
Y Hibino, A Kuroiwa, S Kurosawa, S Kanke, H Hashimoto
This study compared the tensile bond strength of dental luting cements to the titanium castings with gold alloy (Type IV), 12% Au-Ag-Pd alloy and Ni-Cr alloy in dental clinical practice. In this experimental condition, the zinc phosphate cement did not adhere to any dental casting alloy tested. The tensile bond strength of polycarboxylate cement to the titanium castings was 96 kg/cm2, about two times as high as that gold alloy (Type IV). The tensile bond strength of the glass ionomer cement to titanium castings was 32 kg/cm2, about two times as high as that of dental precious alloys. The tensile bond strength of the adhesive resin cement to titanium castings was 220 kg/cm2, about three times as high as that of dental precious alloys.
{"title":"[Bond strength of dental luting cements to titanium castings].","authors":"Y Hibino, A Kuroiwa, S Kurosawa, S Kanke, H Hashimoto","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>This study compared the tensile bond strength of dental luting cements to the titanium castings with gold alloy (Type IV), 12% Au-Ag-Pd alloy and Ni-Cr alloy in dental clinical practice. In this experimental condition, the zinc phosphate cement did not adhere to any dental casting alloy tested. The tensile bond strength of polycarboxylate cement to the titanium castings was 96 kg/cm2, about two times as high as that gold alloy (Type IV). The tensile bond strength of the glass ionomer cement to titanium castings was 32 kg/cm2, about two times as high as that of dental precious alloys. The tensile bond strength of the adhesive resin cement to titanium castings was 220 kg/cm2, about three times as high as that of dental precious alloys.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289748","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}
The durability of four commercially available light-cured composite resins was investigated by thermal cycling, GR containing inorganic fillers treated with the graft polymerization of acryl ester, LF inorganic fillers treated with a silane coupling agent, PC silanized inorganic fillers and organic composite fillers, and the MFR-type SI containing the organic composite fillers. These materials were given 10,000, 30,000 and 50,000 thermal cycles (4 degrees C-60 degrees C) and the deterioration of materials by thermal cycling was evaluated by the measurement of the mechanical properties and the SEM observations of the surface of the thermocycled materials. Compressive strength and bending elastic moduli for all materials did not change greatly by thermal cycling. However, bending strength, toothbrush abrasion resistance and surface hardness decreased with increasing number of thermal cycles between 0 and 30,000, and changed little after 30,000 cycles. The percentage of bending strength after 50,000 thermal cycles to that of the non-thermocycled sample was 75% for GR, 60% for LF, 50% for PC and 65% for SI, respectively. Deterioration of materials was observed as cracks on the surface, which generated at the interface of the filler and matrix. The cracks generated relatively earlier during thermal cycling for SI and PC which contained the organic composite filler, later for LF which contained the silanized inorganic fillers, and the number of cracks on LF were fewer than SI and PC. On the other hand, for GR, no cracks were observed even after 50,000 thermal cycles. From these results, it can be presumed that the pre-treatment of filler by the graft polymerization is more effective to improve the durability of composite resin.
{"title":"[The surface degradation of various light-cured composite resins by thermal cycling].","authors":"S Hirabayashi, R Nomoto, I Harashima, T Hirasawa","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The durability of four commercially available light-cured composite resins was investigated by thermal cycling, GR containing inorganic fillers treated with the graft polymerization of acryl ester, LF inorganic fillers treated with a silane coupling agent, PC silanized inorganic fillers and organic composite fillers, and the MFR-type SI containing the organic composite fillers. These materials were given 10,000, 30,000 and 50,000 thermal cycles (4 degrees C-60 degrees C) and the deterioration of materials by thermal cycling was evaluated by the measurement of the mechanical properties and the SEM observations of the surface of the thermocycled materials. Compressive strength and bending elastic moduli for all materials did not change greatly by thermal cycling. However, bending strength, toothbrush abrasion resistance and surface hardness decreased with increasing number of thermal cycles between 0 and 30,000, and changed little after 30,000 cycles. The percentage of bending strength after 50,000 thermal cycles to that of the non-thermocycled sample was 75% for GR, 60% for LF, 50% for PC and 65% for SI, respectively. Deterioration of materials was observed as cracks on the surface, which generated at the interface of the filler and matrix. The cracks generated relatively earlier during thermal cycling for SI and PC which contained the organic composite filler, later for LF which contained the silanized inorganic fillers, and the number of cracks on LF were fewer than SI and PC. On the other hand, for GR, no cracks were observed even after 50,000 thermal cycles. From these results, it can be presumed that the pre-treatment of filler by the graft polymerization is more effective to improve the durability of composite resin.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289745","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}
O Miyakawa, K Watanabe, S Okawa, S Nakano, N Shiokawa, M Kobayashi, H Tamura
Cast titanium was ground with commercial and experimental wheels made of silicon carbide abrasives, and their grinding performance was investigated. With the vitrified wheels made of the GC abrasive, at a higher the wheel circumferential speed and heavier the grinding pressure, the cutting rate was greater, accompanied by violent wear of the wheel. Being independent of the wheel speed, the grinding ratio reached about 1 under pressure heavier than 100 gf. The MgO-MgCl2-bonded wheels of the C abrasive exhibited a similar tendency. The manner in which the wheel was moved over the work during grinding proved to be very important, compared with the Ni-Cr alloy as reported previously. Only depression of the wheel against the work resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn, due to oxidation of titanium. Even when the wheel was moved over the work, chip-formation process of the cutting edge was far from ideal, and the work surface was contaminated due to reaction of titanium with the abrasive. At a higher wheel circumferential speed, more chips were loaded or built-up in the wheel and strongly rubbed the work surface, resulting in violent wear of the wheel; loading and dislodging of such chips were repeated.
{"title":"[Grinding of titanium. 1. Commercial and experimental wheels made of silicon carbide abrasives].","authors":"O Miyakawa, K Watanabe, S Okawa, S Nakano, N Shiokawa, M Kobayashi, H Tamura","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Cast titanium was ground with commercial and experimental wheels made of silicon carbide abrasives, and their grinding performance was investigated. With the vitrified wheels made of the GC abrasive, at a higher the wheel circumferential speed and heavier the grinding pressure, the cutting rate was greater, accompanied by violent wear of the wheel. Being independent of the wheel speed, the grinding ratio reached about 1 under pressure heavier than 100 gf. The MgO-MgCl2-bonded wheels of the C abrasive exhibited a similar tendency. The manner in which the wheel was moved over the work during grinding proved to be very important, compared with the Ni-Cr alloy as reported previously. Only depression of the wheel against the work resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn, due to oxidation of titanium. Even when the wheel was moved over the work, chip-formation process of the cutting edge was far from ideal, and the work surface was contaminated due to reaction of titanium with the abrasive. At a higher wheel circumferential speed, more chips were loaded or built-up in the wheel and strongly rubbed the work surface, resulting in violent wear of the wheel; loading and dislodging of such chips were repeated.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289743","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}
Although many studies have been made on the reinforcement of the bond between tooth and restorative resin, satisfactory results have not been obtained clinically. Attempts were made to obtain such a reinforced bonding using the aqueous solution of derivatives of amino acid, either N-methacryloyl alanine (MAL) or N-acryloyl alanine (AAL), and 2-hydroxyethyl methacrylate (HEMA). Following the treatment with these surfactants, a tensile bond strength of 103 kgf/cm2 (to enamel) and 80 kgf/cm2 (to dentin) was obtained by MAL-HEMA solution, and that of 99 kgf/cm2 (to enamel) and 58 kgf/cm2 (to dentin) in the case of AAL-HEMA solution. This is considered as the result of either the etching effect of the amino acid derivatives, effect of its reactive products with hydroxyapaptite or reaction between HEMA and an organic component of tooth structure, like a collagen.
虽然对牙体与修复树脂之间的粘结加强进行了许多研究,但临床尚未取得令人满意的结果。利用氨基酸衍生物n -甲基丙烯酰丙氨酸(MAL)或n -丙烯酰丙氨酸(AAL)和2-甲基丙烯酸羟乙酯(HEMA)的水溶液,试图获得这种增强键合。经表面活性剂处理后,MAL-HEMA溶液对牙本质的拉伸强度分别为103 kgf/cm2和80 kgf/cm2, al - hema溶液对牙本质的拉伸强度分别为99 kgf/cm2和58 kgf/cm2。这被认为是氨基酸衍生物的蚀刻效应、其与羟基磷灰石反应产物的作用或HEMA与牙齿结构的有机成分(如胶原蛋白)之间反应的结果。
{"title":"[Adhesion of restorative resin to tooth substance. Treatment of tooth surface with aqueous solution of amino-acid derivatives and HEMA].","authors":"M Takahashi, K Suzuki, H Nakai","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Although many studies have been made on the reinforcement of the bond between tooth and restorative resin, satisfactory results have not been obtained clinically. Attempts were made to obtain such a reinforced bonding using the aqueous solution of derivatives of amino acid, either N-methacryloyl alanine (MAL) or N-acryloyl alanine (AAL), and 2-hydroxyethyl methacrylate (HEMA). Following the treatment with these surfactants, a tensile bond strength of 103 kgf/cm2 (to enamel) and 80 kgf/cm2 (to dentin) was obtained by MAL-HEMA solution, and that of 99 kgf/cm2 (to enamel) and 58 kgf/cm2 (to dentin) in the case of AAL-HEMA solution. This is considered as the result of either the etching effect of the amino acid derivatives, effect of its reactive products with hydroxyapaptite or reaction between HEMA and an organic component of tooth structure, like a collagen.</p>","PeriodicalId":77622,"journal":{"name":"Shika zairyo, kikai = Journal of the Japanese Society for Dental Materials and Devices","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13289746","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}