In order to investigate the influence of abutment material on the stress of implant-supported all-ceramic single crown, a 3D finite element model of implant-supported mandibular first premolar was computed by COSMOS/M...In order to investigate the influence of abutment material on the stress of implant-supported all-ceramic single crown, a 3D finite element model of implant-supported mandibular first premolar was computed by COSMOS/M 2.85 software. Alumina, zirconia, and titanium were used as abutment materials respectively. Vertical 600 N and horizontal 225 N load was applied on the occlusal surface. The results show that the stress distribution of implant-supported single crown was similar for different abutment materials. Maximum stresses within the crown were higher when titanium abutment was used. Maximum stress of titanium abutment was lower than that of ceramic abutment. Within the screw and fixture, maximum stresses had no difference under vertical loading but higher as titanium abutment was used under horizontal loading. There was no difference of maximum stress within the bone when different abutment materials were used. The present findings indicate that the abutment material had no influence on the stress distribution of implant-supported all- ceramic single crown but maximum stress when the titanium abutment was lower than that of ceramic abutment.展开更多
The purpose of this study was to investigate the influence of different luting agents on the stress distribution within the crown, abutment and peri-implant bone of implant-supported all-ceramic single crown. A three-...The purpose of this study was to investigate the influence of different luting agents on the stress distribution within the crown, abutment and peri-implant bone of implant-supported all-ceramic single crown. A three-dimensional finite element model of an implant-supported single crown for the first premolar of mandible was created by COSMOS 2.85. Resin-modified glass ionomer and two different resin adhesives were used to cement the crown and abutment. Vertical 600 N and horizontal 225 N loads were applied to stimulate the condition of chewing. The stress distributions within the all-ceramic crown, abutment and peri-implant bone were analyzed. The experimental results show that the stress distributions of all-ceramic crown, abutment, implant and peri-implant bone were similar when different luting agents were used. The result of present study indicated that luting agents had no influence on the stress distributions of implant-supported all-ceramic single crown.展开更多
The purpose of the present study was to evaluate the effect ofA1203 content on the fracture property of all-ceramics ZrO2. To improve the all-ceramics ZrO2 restoration mechanics properity ,96 samples containing 0,5,10...The purpose of the present study was to evaluate the effect ofA1203 content on the fracture property of all-ceramics ZrO2. To improve the all-ceramics ZrO2 restoration mechanics properity ,96 samples containing 0,5,10 and 15 wt% of A1203 particles were prepared by cold isostatic pressing （200 MPa） and 1 550 ℃ sintered .The phase was analyzed by X-ray diffraction analysis and the bulk densities of the samples were made using Archimedes principle. Samples were randomly divided into four groups. In each group, 24 specimens were prepared so that the angle between notch and specimen＇s long axis is 90° and 60°. Notch depths were 1 mm for all samples. Samples were loaded with three-point bending method. 90° cut samples were used to measure fracture toughness while 60°cut samples were used to observe fracture curve by taking points on the fracture extension path under microscope, plotting points on coordinates, generating fitting curve by software ＂Origin＂, and analyzing the microstructure of the specimen fracture surfaces by scanning electron microscopy （SEM）.The results show that the increment ofA1203 has insignificant effect on the densification of all-ceramic ZrO2.XRD analysis shows that the specimen is comprised of t-ZrO2 and a- A1203 before fracture while fracture surface is m-ZrO2, t-ZrO2 and a-A1203. ZrO2 containing 10% A1203 has the optimum mechanical properties and unconspicuous crack propagation and distribution. The observations may provide a reference for the materials selection, shaoe design, and production orocess of all-ceramic crown and bridge.展开更多
Since the last two decades, restorative dentistry has been witnessing an increased acceptance of the use of the well-known all-ceramic materials for the fabrication of single dental restorations, such as inlays, onlay...Since the last two decades, restorative dentistry has been witnessing an increased acceptance of the use of the well-known all-ceramic materials for the fabrication of single dental restorations, such as inlays, onlays, crowns, anterior and posterior fixed partial dentures (PFPDs). These restorations certainly offer the potential for better biocompatibility coupled with superior aesthetic qualities, especially when compared with the conventional prostheses made from porcelain that is fused with metal ceramic restorations. However, brittleness and extreme sensitivity of all-ceramic materials to micro-like defects or cracks that are inherently present, or may grow, in their microstructure during different laboratory fabrication steps, during necessary clinical adjustments, or from post-placement chewing activity, remain major shortcomings of these dental restorations. In fact, many researchers are of the opinion that the improved mechanical properties can significantly improve the lifetime of all-ceramic restorations and result in enhanced reliability. Therefore, efforts of researchers, as well as manufacturers, have been directed towards the improvement of the mechanical properties in order to overcome such limitations. This article reviews the characterization of the most important mechanical properties that can delineate the behavior of all-ceramic dental materials upon loading. These include fracture mechanics, the brittle nature of ceramics, the relationship between microstructural features and fracture behavior, sources of cracks and flaws that may initiate a fracture and the effect of different fabrication procedures and/or clinical adjustments on the mechanical behavior of dental ceramics are also reviewed and discussed.展开更多
AIM：To provide a side-by-side analysis of the summary of safety and effectiveness data（SSED）submitted to the FDA for the KAMRA and Raindrop corneal inlays for the correction of presbyopia.METHODS：SSED reports subm...AIM：To provide a side-by-side analysis of the summary of safety and effectiveness data（SSED）submitted to the FDA for the KAMRA and Raindrop corneal inlays for the correction of presbyopia.METHODS：SSED reports submitted to the FDA for KAMRA and Raindrop were compared with respect to loss of corrected distance visual acuity（CDVA）,adverse event rates,induction of astigmatism,retention of contrast sensitivity,stability of manifest refractive spherical equivalent（MRSE）,and achieved monocular uncorrected near visual acuity（UNVA）at 24mo.RESULTS：Totally 442/508 of KAMRA patients and344/373 Raindrop patients remained enrolled in the clinical trials at 24mo.The proportion of KAMRA and Raindrop patients who lost≥2 lines of CDVA at 24mo was 3.4%and1%,respectively.The adverse event rate was comparable between the devices.No significant inductions of astigmatism were noted.Both technologies induced a transient myopic shift in MRSE followed by a hyperopic shift and subsequent stabilization.Totally 87%of KAMRA and 98%of Raindrop patients attained a monocular UNVA of J5（20/40）or better at 24mo,28%of KAMRA and 67%of Raindrop patients attained a monocular UNVA of J1（20/20）or better at 24mo.CONCLUSION：Both devices can be considered safe and effective,however,the results of corneal inlay implantation are mixed,and long-term patient satisfaction will likely depend on subjective expectations about the capabilities of the inlays.Variability in surgical technique and postoperative care within and between the two clinical trials diminishes the comparative power of this article.展开更多
目的:观察研究一种纳米复合陶瓷修复儿童第一磨牙大面积牙体缺损的临床效果。方法:针对临床上29例年龄7~15岁,第一磨牙大面积牙体缺损的患者(共35颗),使用CAD/CAM纳米复合陶瓷进行修复,13颗嵌体和22颗高嵌体。修复后24个月内分别对患者...目的:观察研究一种纳米复合陶瓷修复儿童第一磨牙大面积牙体缺损的临床效果。方法:针对临床上29例年龄7~15岁,第一磨牙大面积牙体缺损的患者(共35颗),使用CAD/CAM纳米复合陶瓷进行修复,13颗嵌体和22颗高嵌体。修复后24个月内分别对患者进行修复体形状、色泽、舒适性的满意度调查,使用改良的美国公共卫生服务(United States Public Health Service,USPHS)标准分别评价修复后即刻、12个月和24个月时的临床疗效,评价项目包括修复体完整性、继发龋、边缘适合性、牙龈健康状况和磨耗程度。结果:35颗患牙修复后即刻、24个月修复体形状和舒适性主观评价满意度均达100%,24个月时色泽满意度下降为91.4%。修复体完整性、继发龋以及牙龈健康状况24个月内均100%达到A级。边缘适合性12个月时均达到A级,24个月时88.6%(31例)达到A级,有统计学差异。磨耗程度上,12个月、24个月的临床效果有明显差异,12个月时20%(7例)修复体面出现了小的磨耗平面,24个月时达到了45%(16例),并有17%(6例)出现了较大的磨耗平面,修复体的解剖形态均较好。结论:CAD/CAM纳米复合陶瓷嵌体可以作为儿童第一磨牙大面积牙体缺损的有效治疗方案,疗效稳定,满意度高。展开更多
基金the National Natural Science Foundation of China (No.30801312)
文摘In order to investigate the influence of abutment material on the stress of implant-supported all-ceramic single crown, a 3D finite element model of implant-supported mandibular first premolar was computed by COSMOS/M 2.85 software. Alumina, zirconia, and titanium were used as abutment materials respectively. Vertical 600 N and horizontal 225 N load was applied on the occlusal surface. The results show that the stress distribution of implant-supported single crown was similar for different abutment materials. Maximum stresses within the crown were higher when titanium abutment was used. Maximum stress of titanium abutment was lower than that of ceramic abutment. Within the screw and fixture, maximum stresses had no difference under vertical loading but higher as titanium abutment was used under horizontal loading. There was no difference of maximum stress within the bone when different abutment materials were used. The present findings indicate that the abutment material had no influence on the stress distribution of implant-supported all- ceramic single crown but maximum stress when the titanium abutment was lower than that of ceramic abutment.
基金Funded by the National Natural Science Foundation of China(No.81100784)
文摘The purpose of this study was to investigate the influence of different luting agents on the stress distribution within the crown, abutment and peri-implant bone of implant-supported all-ceramic single crown. A three-dimensional finite element model of an implant-supported single crown for the first premolar of mandible was created by COSMOS 2.85. Resin-modified glass ionomer and two different resin adhesives were used to cement the crown and abutment. Vertical 600 N and horizontal 225 N loads were applied to stimulate the condition of chewing. The stress distributions within the all-ceramic crown, abutment and peri-implant bone were analyzed. The experimental results show that the stress distributions of all-ceramic crown, abutment, implant and peri-implant bone were similar when different luting agents were used. The result of present study indicated that luting agents had no influence on the stress distributions of implant-supported all-ceramic single crown.
基金Funded by the Technology Department Science Fund of Sichaun(No.2011GZ011520)
文摘The purpose of the present study was to evaluate the effect ofA1203 content on the fracture property of all-ceramics ZrO2. To improve the all-ceramics ZrO2 restoration mechanics properity ,96 samples containing 0,5,10 and 15 wt% of A1203 particles were prepared by cold isostatic pressing （200 MPa） and 1 550 ℃ sintered .The phase was analyzed by X-ray diffraction analysis and the bulk densities of the samples were made using Archimedes principle. Samples were randomly divided into four groups. In each group, 24 specimens were prepared so that the angle between notch and specimen＇s long axis is 90° and 60°. Notch depths were 1 mm for all samples. Samples were loaded with three-point bending method. 90° cut samples were used to measure fracture toughness while 60°cut samples were used to observe fracture curve by taking points on the fracture extension path under microscope, plotting points on coordinates, generating fitting curve by software ＂Origin＂, and analyzing the microstructure of the specimen fracture surfaces by scanning electron microscopy （SEM）.The results show that the increment ofA1203 has insignificant effect on the densification of all-ceramic ZrO2.XRD analysis shows that the specimen is comprised of t-ZrO2 and a- A1203 before fracture while fracture surface is m-ZrO2, t-ZrO2 and a-A1203. ZrO2 containing 10% A1203 has the optimum mechanical properties and unconspicuous crack propagation and distribution. The observations may provide a reference for the materials selection, shaoe design, and production orocess of all-ceramic crown and bridge.
文摘Since the last two decades, restorative dentistry has been witnessing an increased acceptance of the use of the well-known all-ceramic materials for the fabrication of single dental restorations, such as inlays, onlays, crowns, anterior and posterior fixed partial dentures (PFPDs). These restorations certainly offer the potential for better biocompatibility coupled with superior aesthetic qualities, especially when compared with the conventional prostheses made from porcelain that is fused with metal ceramic restorations. However, brittleness and extreme sensitivity of all-ceramic materials to micro-like defects or cracks that are inherently present, or may grow, in their microstructure during different laboratory fabrication steps, during necessary clinical adjustments, or from post-placement chewing activity, remain major shortcomings of these dental restorations. In fact, many researchers are of the opinion that the improved mechanical properties can significantly improve the lifetime of all-ceramic restorations and result in enhanced reliability. Therefore, efforts of researchers, as well as manufacturers, have been directed towards the improvement of the mechanical properties in order to overcome such limitations. This article reviews the characterization of the most important mechanical properties that can delineate the behavior of all-ceramic dental materials upon loading. These include fracture mechanics, the brittle nature of ceramics, the relationship between microstructural features and fracture behavior, sources of cracks and flaws that may initiate a fracture and the effect of different fabrication procedures and/or clinical adjustments on the mechanical behavior of dental ceramics are also reviewed and discussed.
文摘AIM：To provide a side-by-side analysis of the summary of safety and effectiveness data（SSED）submitted to the FDA for the KAMRA and Raindrop corneal inlays for the correction of presbyopia.METHODS：SSED reports submitted to the FDA for KAMRA and Raindrop were compared with respect to loss of corrected distance visual acuity（CDVA）,adverse event rates,induction of astigmatism,retention of contrast sensitivity,stability of manifest refractive spherical equivalent（MRSE）,and achieved monocular uncorrected near visual acuity（UNVA）at 24mo.RESULTS：Totally 442/508 of KAMRA patients and344/373 Raindrop patients remained enrolled in the clinical trials at 24mo.The proportion of KAMRA and Raindrop patients who lost≥2 lines of CDVA at 24mo was 3.4%and1%,respectively.The adverse event rate was comparable between the devices.No significant inductions of astigmatism were noted.Both technologies induced a transient myopic shift in MRSE followed by a hyperopic shift and subsequent stabilization.Totally 87%of KAMRA and 98%of Raindrop patients attained a monocular UNVA of J5（20/40）or better at 24mo,28%of KAMRA and 67%of Raindrop patients attained a monocular UNVA of J1（20/20）or better at 24mo.CONCLUSION：Both devices can be considered safe and effective,however,the results of corneal inlay implantation are mixed,and long-term patient satisfaction will likely depend on subjective expectations about the capabilities of the inlays.Variability in surgical technique and postoperative care within and between the two clinical trials diminishes the comparative power of this article.
文摘目的:观察研究一种纳米复合陶瓷修复儿童第一磨牙大面积牙体缺损的临床效果。方法:针对临床上29例年龄7~15岁,第一磨牙大面积牙体缺损的患者(共35颗),使用CAD/CAM纳米复合陶瓷进行修复,13颗嵌体和22颗高嵌体。修复后24个月内分别对患者进行修复体形状、色泽、舒适性的满意度调查,使用改良的美国公共卫生服务(United States Public Health Service,USPHS)标准分别评价修复后即刻、12个月和24个月时的临床疗效,评价项目包括修复体完整性、继发龋、边缘适合性、牙龈健康状况和磨耗程度。结果:35颗患牙修复后即刻、24个月修复体形状和舒适性主观评价满意度均达100%,24个月时色泽满意度下降为91.4%。修复体完整性、继发龋以及牙龈健康状况24个月内均100%达到A级。边缘适合性12个月时均达到A级,24个月时88.6%(31例)达到A级,有统计学差异。磨耗程度上,12个月、24个月的临床效果有明显差异,12个月时20%(7例)修复体面出现了小的磨耗平面,24个月时达到了45%(16例),并有17%(6例)出现了较大的磨耗平面,修复体的解剖形态均较好。结论:CAD/CAM纳米复合陶瓷嵌体可以作为儿童第一磨牙大面积牙体缺损的有效治疗方案,疗效稳定,满意度高。
