The microstructure and properties of a series of binary Ti-Nb alloys for dental prostheses with niobium contents ranging from 5% to 20% were investigated. The experimental results indicate that the crystal structure a...The microstructure and properties of a series of binary Ti-Nb alloys for dental prostheses with niobium contents ranging from 5% to 20% were investigated. The experimental results indicate that the crystal structure and morphology of Ti-Nb alloys are sensitive to their niobium contents. When Nb content is 5%, the acicular α crystal grain is observed. When Nb content is 10%, the coarse equiaxed crystal grain and the fine, acicular α crystal grain are observed. When Nb content is 15%, only the α equiaxed crystal grain is observed. When the alloy contains 20%Nb, the equiaxed and dendritic α crystal grain are observed. For Ti-Nb alloys, the increase of Nb content modifies the microstructure of Ti-Nb alloys significantly and decreases their compression elastic modulus, in which Ti-20Nb alloy shows the largest compression strength and Ti-5Nb alloy shows the best plasticity. The dry wear resistance of Ti-Nb alloys against Gr15 ball was investigated on CJS111A ball-disk wear instrument. For Ti-Nb alloys, Ti-10Nb alloy shows a smallest steady friction coefficient, Ti-5Nb alloy shows the smallest wear depth and best wear resistance, and Ti-15Nb alloy shows the largest wear depth and worst wear resistance. The phenomenon of furrow cut happens and furrows form during wear tests.展开更多
In order to well design tribosystems of dental CAD-CAM restorations, an understanding of the tribological mechanisms of dental machinable porcelain are essential. The friction and wear behavior of new generation indus...In order to well design tribosystems of dental CAD-CAM restorations, an understanding of the tribological mechanisms of dental machinable porcelain are essential. The friction and wear behavior of new generation industrially prefabricated Cerec Vitablocs Mark II against uniform Si3N4 ball has been performed using a small amplitude reciprocating apparatus under simulating oral conditions. The loads of 10-40 N, reciprocating amplitudes of 100-500 urn, frequencies of 1-4 Hz and two lubrications (no / artificial saliva lubrication) were selected. Tests lasting up to 10 000 cycles were conducted. The results show that Cerec Vitablocs Mark II record a friction coefficient of 0.55-0.84. Artificial saliva plays a lubricant effect during wear process. Among three parameters of the test on friction coefficient and wear depth of dental machinable porcelains, the load effect is prominent. Abrasive wear is the main wear mechanism, but brittle cracks and delamination are more popular especially under unlubricated friction.展开更多
AIM To test the reliability of the Sawai’s classification for dental cervical abrasions.METHODSIntraoral photographs of 70 teeth from 23 patients with tooth abrasions were taken by the first examiner MS.The teeth wer...AIM To test the reliability of the Sawai’s classification for dental cervical abrasions.METHODSIntraoral photographs of 70 teeth from 23 patients with tooth abrasions were taken by the first examiner MS.The teeth were marked and the photos were maintained in a soft copy sequentially.Two other examiners FA and SC were trained in the use of the classification and any clarifications needed were provided at the beginning of the study.Each examiner was then given the soft copy of the complied photographs and was asked to classify the dental cervical abrasion according to their understanding of the Sawai’s classification.They were given sheets to write their responses for every marked tooth.All the examiners were blinded to each other’s observations which were then tested for inter-rater agreement among the three examiners.RESULTSThe 70 teeth with tooth abrasions from 23 patients were examined by 3 investigators(MS,FA and SC)to test the reliability of the Sawai’s classification system for tooth abrasion.Each examiner marked their responses in separate sheets which were blinded to each other.The kappa statistics were performed for inter-rater agreement among the three examiners.The level of agreement was evaluated according to the six-level nomenclature given by Landis and Koch.ICC and 95%CI between two examiners,i.e.,the inter-rater agreement among 1^(st) examiner(MS) and 2^(nd) examiner(FA) was 0.89.The inter-rater agreement among 1^(st) examiner(MS) and 3^(rd) examiner(SC) was 0.89.And the inter-rater agreement among 2^(nd) examiner(FA) and 3^(rd) examiner(SC) was 0.83.All the three comparisons show an almost perfect agreement between them.CONCLUSIONThere is an almost perfect agreement between multiple observers for classifying dental cervical abrasions using Sawai’s classification.Hence,this classification is reliable.展开更多
The fracture and tribological evaluation of dental composite resin containing pre-polymerized particle fillers were investigated. Composite resins, e.g. metafil, silux plus, heliomolar and palfique estelite were selec...The fracture and tribological evaluation of dental composite resin containing pre-polymerized particle fillers were investigated. Composite resins, e.g. metafil, silux plus, heliomolar and palfique estelite were selected as specimens in order to evaluate the effects of pre-polymerized particle filler on the fracture and wear characteristics of composite resins. In the wear tests, a ball-on-flat wear test method was used. The friction coefficient of metafil was quite high. The wear resistance of silux plus and palfique estelite was better than that of metafil and heliomolar under the same experimental condition. The main wear mechanism of composite resins containing pre-polymerized particle fillers was an abrasive wear by brittle fracture of pre-polymerized particles and by debonding of fillers and matrix.展开更多
The aim of this study was to evaluate the effect of chewing simulation on wear of artificial enamel abraded against zirconia-based crowns. Fifteen crown preparations were scanned for the manufacturing of crowns using ...The aim of this study was to evaluate the effect of chewing simulation on wear of artificial enamel abraded against zirconia-based crowns. Fifteen crown preparations were scanned for the manufacturing of crowns using computer-aided-design/computer-aided-machining technique (CAD/CAM), according to the following (n = 5): Polished (PM) and glazed (GM) monolithic zirconia (1.5 mm uniform thickness), and Bilayer (BL - 0.8 mm zirconia coping, 0.7 mm porcelain veneer) crowns. The samples were cemented and chewing simulation (2.5 million cycles/0-80N/artificial saliva/37°C) was performed with steatite indenters (6 mm diameter) as antagonists. Assuming the uniformity of the unaged samples, antagonists were scanned using a surface profilometer and the material loss volume was calculated. Roughness of the crowns’ occlusal surface was also analyzed using the profilometer. Scanning electron microscopy was used to characterize the abraded surface. One-way ANOVA and Tukey test (p = 0.05) were employed for analysis of wear results. A significant difference was observed among the groups (p 3 ± 0.015) than those abraded against monolithic zirconia, polished (PM - 0.167 mm3 ± 0.02) and glazed (0.101 mm3 ± 0.03), which were similar to each other. Veneering porcelain results in more pronounced wear of the artificial enamel than monolithic zirconia. However, mastication against monolithic Y-TZP also imposes wear to the opposing teeth.展开更多
目的:通过对临床损伤失效的全瓷修复体的损伤形貌观察,分析全瓷修复体饰瓷疲劳损伤的机制和过程,以及缺陷与饰瓷损伤的关系。方法:收集断裂或破碎的全瓷修复体,体式显微镜和扫描电子显微镜(scanning electron microscope,SEM)观察其断...目的:通过对临床损伤失效的全瓷修复体的损伤形貌观察,分析全瓷修复体饰瓷疲劳损伤的机制和过程,以及缺陷与饰瓷损伤的关系。方法:收集断裂或破碎的全瓷修复体,体式显微镜和扫描电子显微镜(scanning electron microscope,SEM)观察其断裂面和咬合面微观形貌以及饰瓷的缺陷,X线衍射能谱分析(energy-dispersive X-ray spectroscopy,EDS)饰瓷内不均质部分的化学成分。运用陶瓷损伤形貌分析的方法,分析全瓷修复体的断裂方式和损伤特征。结果:全瓷修复体的最终损伤失效包括完全断裂、饰瓷崩瓷和饰瓷脱瓷3种方式。氧化铝全瓷冠发生了完全断裂,氧化锆全瓷冠发生饰瓷崩瓷或饰瓷脱瓷。饰瓷疲劳损伤包括表面磨损、锥状裂纹和饰瓷脱瓷3种模式。饰瓷表面发现气孔和污染颗粒缺陷。结论:全瓷修复体应设计多点咬合接触,分散咬合应力。饰瓷脱瓷发生于饰瓷层过薄的情况,适当的饰瓷厚度保证饰瓷的抗疲劳损伤能力。临床需严格控制饰瓷烧结过程的环境污染。展开更多
基金Project(20080440850) supported by China Postdoctoral Science FoundationProject(ZJY0605-02) supported by the Natural Science Foundation of Heilongjiang Province, China
文摘The microstructure and properties of a series of binary Ti-Nb alloys for dental prostheses with niobium contents ranging from 5% to 20% were investigated. The experimental results indicate that the crystal structure and morphology of Ti-Nb alloys are sensitive to their niobium contents. When Nb content is 5%, the acicular α crystal grain is observed. When Nb content is 10%, the coarse equiaxed crystal grain and the fine, acicular α crystal grain are observed. When Nb content is 15%, only the α equiaxed crystal grain is observed. When the alloy contains 20%Nb, the equiaxed and dendritic α crystal grain are observed. For Ti-Nb alloys, the increase of Nb content modifies the microstructure of Ti-Nb alloys significantly and decreases their compression elastic modulus, in which Ti-20Nb alloy shows the largest compression strength and Ti-5Nb alloy shows the best plasticity. The dry wear resistance of Ti-Nb alloys against Gr15 ball was investigated on CJS111A ball-disk wear instrument. For Ti-Nb alloys, Ti-10Nb alloy shows a smallest steady friction coefficient, Ti-5Nb alloy shows the smallest wear depth and best wear resistance, and Ti-15Nb alloy shows the largest wear depth and worst wear resistance. The phenomenon of furrow cut happens and furrows form during wear tests.
基金supported by grant 50305030 from the Chinese Natural Science Foundationgrant 2003033526 from China Postdoctoral Science Foundationgrant 03SG022 from Sicence an d Technology Office of Sichuan Province.
文摘In order to well design tribosystems of dental CAD-CAM restorations, an understanding of the tribological mechanisms of dental machinable porcelain are essential. The friction and wear behavior of new generation industrially prefabricated Cerec Vitablocs Mark II against uniform Si3N4 ball has been performed using a small amplitude reciprocating apparatus under simulating oral conditions. The loads of 10-40 N, reciprocating amplitudes of 100-500 urn, frequencies of 1-4 Hz and two lubrications (no / artificial saliva lubrication) were selected. Tests lasting up to 10 000 cycles were conducted. The results show that Cerec Vitablocs Mark II record a friction coefficient of 0.55-0.84. Artificial saliva plays a lubricant effect during wear process. Among three parameters of the test on friction coefficient and wear depth of dental machinable porcelains, the load effect is prominent. Abrasive wear is the main wear mechanism, but brittle cracks and delamination are more popular especially under unlubricated friction.
文摘AIM To test the reliability of the Sawai’s classification for dental cervical abrasions.METHODSIntraoral photographs of 70 teeth from 23 patients with tooth abrasions were taken by the first examiner MS.The teeth were marked and the photos were maintained in a soft copy sequentially.Two other examiners FA and SC were trained in the use of the classification and any clarifications needed were provided at the beginning of the study.Each examiner was then given the soft copy of the complied photographs and was asked to classify the dental cervical abrasion according to their understanding of the Sawai’s classification.They were given sheets to write their responses for every marked tooth.All the examiners were blinded to each other’s observations which were then tested for inter-rater agreement among the three examiners.RESULTSThe 70 teeth with tooth abrasions from 23 patients were examined by 3 investigators(MS,FA and SC)to test the reliability of the Sawai’s classification system for tooth abrasion.Each examiner marked their responses in separate sheets which were blinded to each other.The kappa statistics were performed for inter-rater agreement among the three examiners.The level of agreement was evaluated according to the six-level nomenclature given by Landis and Koch.ICC and 95%CI between two examiners,i.e.,the inter-rater agreement among 1^(st) examiner(MS) and 2^(nd) examiner(FA) was 0.89.The inter-rater agreement among 1^(st) examiner(MS) and 3^(rd) examiner(SC) was 0.89.And the inter-rater agreement among 2^(nd) examiner(FA) and 3^(rd) examiner(SC) was 0.83.All the three comparisons show an almost perfect agreement between them.CONCLUSIONThere is an almost perfect agreement between multiple observers for classifying dental cervical abrasions using Sawai’s classification.Hence,this classification is reliable.
文摘The fracture and tribological evaluation of dental composite resin containing pre-polymerized particle fillers were investigated. Composite resins, e.g. metafil, silux plus, heliomolar and palfique estelite were selected as specimens in order to evaluate the effects of pre-polymerized particle filler on the fracture and wear characteristics of composite resins. In the wear tests, a ball-on-flat wear test method was used. The friction coefficient of metafil was quite high. The wear resistance of silux plus and palfique estelite was better than that of metafil and heliomolar under the same experimental condition. The main wear mechanism of composite resins containing pre-polymerized particle fillers was an abrasive wear by brittle fracture of pre-polymerized particles and by debonding of fillers and matrix.
文摘The aim of this study was to evaluate the effect of chewing simulation on wear of artificial enamel abraded against zirconia-based crowns. Fifteen crown preparations were scanned for the manufacturing of crowns using computer-aided-design/computer-aided-machining technique (CAD/CAM), according to the following (n = 5): Polished (PM) and glazed (GM) monolithic zirconia (1.5 mm uniform thickness), and Bilayer (BL - 0.8 mm zirconia coping, 0.7 mm porcelain veneer) crowns. The samples were cemented and chewing simulation (2.5 million cycles/0-80N/artificial saliva/37°C) was performed with steatite indenters (6 mm diameter) as antagonists. Assuming the uniformity of the unaged samples, antagonists were scanned using a surface profilometer and the material loss volume was calculated. Roughness of the crowns’ occlusal surface was also analyzed using the profilometer. Scanning electron microscopy was used to characterize the abraded surface. One-way ANOVA and Tukey test (p = 0.05) were employed for analysis of wear results. A significant difference was observed among the groups (p 3 ± 0.015) than those abraded against monolithic zirconia, polished (PM - 0.167 mm3 ± 0.02) and glazed (0.101 mm3 ± 0.03), which were similar to each other. Veneering porcelain results in more pronounced wear of the artificial enamel than monolithic zirconia. However, mastication against monolithic Y-TZP also imposes wear to the opposing teeth.
文摘目的:通过对临床损伤失效的全瓷修复体的损伤形貌观察,分析全瓷修复体饰瓷疲劳损伤的机制和过程,以及缺陷与饰瓷损伤的关系。方法:收集断裂或破碎的全瓷修复体,体式显微镜和扫描电子显微镜(scanning electron microscope,SEM)观察其断裂面和咬合面微观形貌以及饰瓷的缺陷,X线衍射能谱分析(energy-dispersive X-ray spectroscopy,EDS)饰瓷内不均质部分的化学成分。运用陶瓷损伤形貌分析的方法,分析全瓷修复体的断裂方式和损伤特征。结果:全瓷修复体的最终损伤失效包括完全断裂、饰瓷崩瓷和饰瓷脱瓷3种方式。氧化铝全瓷冠发生了完全断裂,氧化锆全瓷冠发生饰瓷崩瓷或饰瓷脱瓷。饰瓷疲劳损伤包括表面磨损、锥状裂纹和饰瓷脱瓷3种模式。饰瓷表面发现气孔和污染颗粒缺陷。结论:全瓷修复体应设计多点咬合接触,分散咬合应力。饰瓷脱瓷发生于饰瓷层过薄的情况,适当的饰瓷厚度保证饰瓷的抗疲劳损伤能力。临床需严格控制饰瓷烧结过程的环境污染。
