The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the Ca...The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the CaO/SiO_(2)slag mass ratio(C/S ratio)on the dissolution rate of alumina-based refractory ceramics was investigated.The results indicate that the dissolution rate increases with an increase of the C/S ratio and is mainly controlled by diffusion.During the early stage of dissolution,for all C/S ratios,the dissolution process conforms to the classical invariant interface approximation model.During the later stage of dissolution,when the C/S ratio is≥6,the dissolution process is significantly different from the model above because of the formation of a thick interfacial layer,which can be explained by dissolution kinetics.展开更多
Alumina-based foam ceramic filters were fabricated by using alumina,SiC,magnesia powder as major materials.It has been found that this ceramic filter has a uniform macrostructure for filtering molten metals.The influe...Alumina-based foam ceramic filters were fabricated by using alumina,SiC,magnesia powder as major materials.It has been found that this ceramic filter has a uniform macrostructure for filtering molten metals.The influences of SiC and magnesia content,the sintering temperatures on ceramic properties were discussed.Alumina-based foam ceramic filters containing 2.2 mass% magnesia and 7.6 mass% SiC has a compressive strength of 1.36 MPa and a thermal shock resistance of 5 times.Its main phases after 1 hour sintering at 1 500℃ consist of alumina,silicon carbide,spinel and mullite.展开更多
The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against cer...The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against ceramic crowns in posterior region. The selected studies were analyzed in regard to type of crowns, natural antagonist, measuring protocol and outcome. From a yield of 1 000 titles, 43 articles were selected for full-text analysis; finally, no in vitro and only five in vivo studies met the inclusion criteria. As there is heterogeneity in design, used measuring method, ceramics and analysis-form, a meta-analysis was not possible. Results of these studies are very controversial which makes a scientifically valid comparison impossible. This review indicated that some all-ceramic crowns are as wear friendly as metal-ceramic crowns. Up to now, it has been impossible to associate tooth wear with any specific causal agent. The role of ceramic surface treatment that might be responsible for the changing in rate of tooth wear seems undetermined as yet through clinical trials. The literature reveals that studies on this topic are subject to a substantial amount of bias. Therefore, additional clinical studies, properly designed to diminish bias, are warranted.展开更多
The fracture toughness and fracture work of A12O3/SiC prismatic ceramic composites was evaluated in this paper, which showed the fracture energy was improved greatly. Based on the observation 'for crack propagat...The fracture toughness and fracture work of A12O3/SiC prismatic ceramic composites was evaluated in this paper, which showed the fracture energy was improved greatly. Based on the observation 'for crack propagation and fracture morphology, the fracture behavior of the prismatic composites was analyzed. In the bending test, the composites displayed a non-catastrophic behavior and a graceful failure with reasonable load-carrying capability.展开更多
Y2O3-stabilized tetragonal zirconia polycrystalline （Y-TZP） ceramics with high-performance were prepared for dental ap- plication by use of the micro-emulsion and two-step sintering method. The crystal phase, morpho...Y2O3-stabilized tetragonal zirconia polycrystalline （Y-TZP） ceramics with high-performance were prepared for dental ap- plication by use of the micro-emulsion and two-step sintering method. The crystal phase, morphology, and microstructure of the reaction products were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron mi- croscopy （TEM）. XRD results show that the ceramics mainly consist of tetragonal zirconia. Physical and mechanical properties test results show that the bending strength, fracture toughness, and the density of full sintered Y-TZP ceramics are 1150 MPa, 5.53 MPa.m1/2, and 6.08 g/cm3, respectively, which suggest that the material is relatively suitable for dental restoration. The dental base crown machined with this material by CAD/CAM system exhibits a verisimilitude configuration and the material＇s expansion coefficient well matches that of the glaze. These results further indicate that the product can be used as a promising new ceramic material to fabricate dental base crowns and bridges.展开更多
A mechanically retentive structure and meticulous surface cleanliness are critical factors in providing fracture resistance and clinical success of metal ceramic restorations. This investigation compared the porcelain...A mechanically retentive structure and meticulous surface cleanliness are critical factors in providing fracture resistance and clinical success of metal ceramic restorations. This investigation compared the porcelain/metal interfaces of deliberate compressive fractures of ceramic crowns between conventional preparation and application of the Radio Frequency Glow Discharge Treatment (RFGDT) before each bonding step. It evaluated RFGDT’s capacity to improve wetting effectiveness and minimize porosity. Twelve metal ceramic crowns were fabricated identically. RFGDT was applied to the metal substructures of half the specimens before the ceramic layering process. All specimens were fractured in the same manner by an applied compressive force to simulate dental occlusive failure. Fracture surfaces were inspected by light and scanning electron microscopy. Quantitative analyses of images were performed to identify numbers, locations of cracks, porosity patterns, and other morphological correlates of the fracture zones. There were significantly fewer voids per millimeter at the interfaces in the RFGDT group than in the non-RFGDT group (t = 2.377, df = 9, p = 0.021). There was a significant difference in the number of horizontal cracks per millimeter between the groups (t = 2.132, df = 7, p = 0.035), with more cracks occurring in the non-RFGDT group. RFGDT can improve the integrity of metal ceramic crowns by increasing the substratum surface energy, improving porcelain wetting and spreading and thereby diminishing the numbers of interfacial voids available for initiation of fracture. Routine application of RFGDT should result in fewer cracks along metal/ceramic interfaces in all restorative preparations.展开更多
目的:观察生物活性陶瓷材料iRoot BP Plus^(■)(Innovative BioCeramix Inc,Vancouver,BC,Canada)在儿童年轻恒前牙复杂冠折牙髓切断术中的应用,并对其预后进行分析,为该术式的更广泛应用提供临床参考。方法:收集2017年3月至2022年9月...目的:观察生物活性陶瓷材料iRoot BP Plus^(■)(Innovative BioCeramix Inc,Vancouver,BC,Canada)在儿童年轻恒前牙复杂冠折牙髓切断术中的应用,并对其预后进行分析,为该术式的更广泛应用提供临床参考。方法:收集2017年3月至2022年9月因恒前牙复杂冠折就诊于北京大学口腔医院急诊科,行以生物活性陶瓷iRoot BP Plus^(■)为盖髓剂的牙髓切断术患者。根据患者术前根尖片和初诊病历显示为年轻恒牙者,纳入97颗年轻恒牙进行研究。收集患者初诊及复查时的临床及影像学检查资料,临床检查包括根尖孔形成情况、松动度、牙冠颜色、牙髓活力测试(冷测)、有无脓肿和瘘管,影像学检查包括根周膜连续性、根尖周低密度影像、复诊时盖髓剂下方牙本质桥形成情况、髓腔及根管钙化情况,并对上述结果进行分析。结果:最终纳入有复诊记录的64例患者共75颗患牙,其中男性37例(57.8%),女性27例(42.2%),就诊时平均年龄为9.1岁,平均随访时长19.3个月。采用iRoot BP Plus^(■)盖髓的牙髓切断术后6个月成功率为96.0%,术后1年成功率为94.7%。术后复查2年以上者共23例,累计失败6例。成功率在患牙就诊时距外伤的时间是否超过24 h组中(P=0.61)以及是否松动组中(P=0.28)的差异无统计学意义。结论:对无移位性损伤的年轻恒牙复杂冠折患牙,采用iRoot BP Plus^(■)盖髓的牙髓切断术1年成功率很高,该术式具备广泛推广价值。展开更多
目的:探究纤维桩+复合树脂+氧化锆全瓷冠修复根管治疗后后牙楔状缺损患者的效果及美观满意度。方法:纳入2022年1月-2023年1月在笔者医院就诊的102例后牙楔状缺损患者,根据患者自主选择意愿分为研究组(n=50)和对照组(n=52),对照组行金属...目的:探究纤维桩+复合树脂+氧化锆全瓷冠修复根管治疗后后牙楔状缺损患者的效果及美观满意度。方法:纳入2022年1月-2023年1月在笔者医院就诊的102例后牙楔状缺损患者,根据患者自主选择意愿分为研究组(n=50)和对照组(n=52),对照组行金属桩核+金属烤瓷冠修复,研究组行纤维桩+复合树脂+氧化锆全瓷冠修复。6个月后,对比两组临床疗效,观察两组牙周健康情况(牙龈指数、菌斑指数、龈沟出血指数),检测牙周炎症[肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)、白细胞介素-4(Interleukin-4,IL-4)、白细胞介素-6(Interleukin-6,IL-6)],调查美观满意度[美国公共健康服务标准(United states public health service,USPHS)]和实用度(咀嚼功能、咬合情况、语言功能),比较两组并发症发生情况。结果:治疗后,研究组治疗有效率达92.00%,高于对照组的76.92%(P<0.05);两组牙周健康相关指数及TNF-α、IL-4、IL-6均较治疗前降低,且研究组降低幅度大于对照组(P<0.05);治疗后,研究组牙齿表面形态、色泽协调性、边缘着色满意度均高于对照组(P<0.05),两组咀嚼功能、咬合情况、语言功能均较治疗前提高,但差异无统计学意义(P>0.05);两组并发症发生率比较治疗组低于对照组(P<0.05)。结论:采用纤维桩+复合树脂+氧化锆全瓷冠修复根管治疗后后牙楔状缺损能够减轻炎症反应,提升患者牙周健康,增加美观满意度及实用度,疗效显著,安全性高。展开更多
基金supported by the National Natural Science Foundation of China(52272022)the Special Project of Central Government for Local Science and Technology Development of Hubei Province(2019ZYYD076)the Innovation and Entrepreneurship Fund of Wuhan University of Science and Technology(D202202171045002669).
文摘The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the CaO/SiO_(2)slag mass ratio(C/S ratio)on the dissolution rate of alumina-based refractory ceramics was investigated.The results indicate that the dissolution rate increases with an increase of the C/S ratio and is mainly controlled by diffusion.During the early stage of dissolution,for all C/S ratios,the dissolution process conforms to the classical invariant interface approximation model.During the later stage of dissolution,when the C/S ratio is≥6,the dissolution process is significantly different from the model above because of the formation of a thick interfacial layer,which can be explained by dissolution kinetics.
基金The project is supported by National Natural Science Foundation of China:50334030PhD Fund of Liaoning Province:20041010.
文摘Alumina-based foam ceramic filters were fabricated by using alumina,SiC,magnesia powder as major materials.It has been found that this ceramic filter has a uniform macrostructure for filtering molten metals.The influences of SiC and magnesia content,the sintering temperatures on ceramic properties were discussed.Alumina-based foam ceramic filters containing 2.2 mass% magnesia and 7.6 mass% SiC has a compressive strength of 1.36 MPa and a thermal shock resistance of 5 times.Its main phases after 1 hour sintering at 1 500℃ consist of alumina,silicon carbide,spinel and mullite.
文摘The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against ceramic crowns in posterior region. The selected studies were analyzed in regard to type of crowns, natural antagonist, measuring protocol and outcome. From a yield of 1 000 titles, 43 articles were selected for full-text analysis; finally, no in vitro and only five in vivo studies met the inclusion criteria. As there is heterogeneity in design, used measuring method, ceramics and analysis-form, a meta-analysis was not possible. Results of these studies are very controversial which makes a scientifically valid comparison impossible. This review indicated that some all-ceramic crowns are as wear friendly as metal-ceramic crowns. Up to now, it has been impossible to associate tooth wear with any specific causal agent. The role of ceramic surface treatment that might be responsible for the changing in rate of tooth wear seems undetermined as yet through clinical trials. The literature reveals that studies on this topic are subject to a substantial amount of bias. Therefore, additional clinical studies, properly designed to diminish bias, are warranted.
文摘The fracture toughness and fracture work of A12O3/SiC prismatic ceramic composites was evaluated in this paper, which showed the fracture energy was improved greatly. Based on the observation 'for crack propagation and fracture morphology, the fracture behavior of the prismatic composites was analyzed. In the bending test, the composites displayed a non-catastrophic behavior and a graceful failure with reasonable load-carrying capability.
文摘Y2O3-stabilized tetragonal zirconia polycrystalline （Y-TZP） ceramics with high-performance were prepared for dental ap- plication by use of the micro-emulsion and two-step sintering method. The crystal phase, morphology, and microstructure of the reaction products were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron mi- croscopy （TEM）. XRD results show that the ceramics mainly consist of tetragonal zirconia. Physical and mechanical properties test results show that the bending strength, fracture toughness, and the density of full sintered Y-TZP ceramics are 1150 MPa, 5.53 MPa.m1/2, and 6.08 g/cm3, respectively, which suggest that the material is relatively suitable for dental restoration. The dental base crown machined with this material by CAD/CAM system exhibits a verisimilitude configuration and the material＇s expansion coefficient well matches that of the glaze. These results further indicate that the product can be used as a promising new ceramic material to fabricate dental base crowns and bridges.
文摘A mechanically retentive structure and meticulous surface cleanliness are critical factors in providing fracture resistance and clinical success of metal ceramic restorations. This investigation compared the porcelain/metal interfaces of deliberate compressive fractures of ceramic crowns between conventional preparation and application of the Radio Frequency Glow Discharge Treatment (RFGDT) before each bonding step. It evaluated RFGDT’s capacity to improve wetting effectiveness and minimize porosity. Twelve metal ceramic crowns were fabricated identically. RFGDT was applied to the metal substructures of half the specimens before the ceramic layering process. All specimens were fractured in the same manner by an applied compressive force to simulate dental occlusive failure. Fracture surfaces were inspected by light and scanning electron microscopy. Quantitative analyses of images were performed to identify numbers, locations of cracks, porosity patterns, and other morphological correlates of the fracture zones. There were significantly fewer voids per millimeter at the interfaces in the RFGDT group than in the non-RFGDT group (t = 2.377, df = 9, p = 0.021). There was a significant difference in the number of horizontal cracks per millimeter between the groups (t = 2.132, df = 7, p = 0.035), with more cracks occurring in the non-RFGDT group. RFGDT can improve the integrity of metal ceramic crowns by increasing the substratum surface energy, improving porcelain wetting and spreading and thereby diminishing the numbers of interfacial voids available for initiation of fracture. Routine application of RFGDT should result in fewer cracks along metal/ceramic interfaces in all restorative preparations.
文摘目的:观察生物活性陶瓷材料iRoot BP Plus^(■)(Innovative BioCeramix Inc,Vancouver,BC,Canada)在儿童年轻恒前牙复杂冠折牙髓切断术中的应用,并对其预后进行分析,为该术式的更广泛应用提供临床参考。方法:收集2017年3月至2022年9月因恒前牙复杂冠折就诊于北京大学口腔医院急诊科,行以生物活性陶瓷iRoot BP Plus^(■)为盖髓剂的牙髓切断术患者。根据患者术前根尖片和初诊病历显示为年轻恒牙者,纳入97颗年轻恒牙进行研究。收集患者初诊及复查时的临床及影像学检查资料,临床检查包括根尖孔形成情况、松动度、牙冠颜色、牙髓活力测试(冷测)、有无脓肿和瘘管,影像学检查包括根周膜连续性、根尖周低密度影像、复诊时盖髓剂下方牙本质桥形成情况、髓腔及根管钙化情况,并对上述结果进行分析。结果:最终纳入有复诊记录的64例患者共75颗患牙,其中男性37例(57.8%),女性27例(42.2%),就诊时平均年龄为9.1岁,平均随访时长19.3个月。采用iRoot BP Plus^(■)盖髓的牙髓切断术后6个月成功率为96.0%,术后1年成功率为94.7%。术后复查2年以上者共23例,累计失败6例。成功率在患牙就诊时距外伤的时间是否超过24 h组中(P=0.61)以及是否松动组中(P=0.28)的差异无统计学意义。结论:对无移位性损伤的年轻恒牙复杂冠折患牙,采用iRoot BP Plus^(■)盖髓的牙髓切断术1年成功率很高,该术式具备广泛推广价值。
文摘目的:探究纤维桩+复合树脂+氧化锆全瓷冠修复根管治疗后后牙楔状缺损患者的效果及美观满意度。方法:纳入2022年1月-2023年1月在笔者医院就诊的102例后牙楔状缺损患者,根据患者自主选择意愿分为研究组(n=50)和对照组(n=52),对照组行金属桩核+金属烤瓷冠修复,研究组行纤维桩+复合树脂+氧化锆全瓷冠修复。6个月后,对比两组临床疗效,观察两组牙周健康情况(牙龈指数、菌斑指数、龈沟出血指数),检测牙周炎症[肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)、白细胞介素-4(Interleukin-4,IL-4)、白细胞介素-6(Interleukin-6,IL-6)],调查美观满意度[美国公共健康服务标准(United states public health service,USPHS)]和实用度(咀嚼功能、咬合情况、语言功能),比较两组并发症发生情况。结果:治疗后,研究组治疗有效率达92.00%,高于对照组的76.92%(P<0.05);两组牙周健康相关指数及TNF-α、IL-4、IL-6均较治疗前降低,且研究组降低幅度大于对照组(P<0.05);治疗后,研究组牙齿表面形态、色泽协调性、边缘着色满意度均高于对照组(P<0.05),两组咀嚼功能、咬合情况、语言功能均较治疗前提高,但差异无统计学意义(P>0.05);两组并发症发生率比较治疗组低于对照组(P<0.05)。结论:采用纤维桩+复合树脂+氧化锆全瓷冠修复根管治疗后后牙楔状缺损能够减轻炎症反应,提升患者牙周健康,增加美观满意度及实用度,疗效显著,安全性高。
