共查询到20条相似文献，搜索用时 31 毫秒
1.
Statement of problem
Heat treatment has been used to reduce the residual stress of alloys fabricated by selective laser melting (SLM) to avoid deformation. Co-Cr metal-ceramic alloys are used to fabricate metal-ceramic restorations and removable partial dentures (RPDs) on the same substrate by SLM. A heat treatment that enables the fabrication of metal-ceramic restorations and RPDs with excellent mechanical properties should be evaluated.Purpose
The purpose of this in vitro study was to determine the effects of 2 heat treatments on the mechanical properties of SLM Co-Cr metal-ceramic alloys intended for the fabrication of thin RPDs.Material and methods
Tensile bars were manufactured using cast metal-ceramics (C-MC group), RPD alloys (C-RPD group), and SLM Co-Cr metal-ceramic alloys. The SLM specimens were subjected to 2 different heat treatments, L1 at 880°C and L2 at 1100°C, and were further divided into subgroups (L1-MC, L1-RPD, L2-MC, and L2-RPD). Thirty-six tensile specimens were prepared in C-RPD, L1-RPD, and L2-RPD (simulated partial denture alloys for clinical use) and in C-MC, L1-MC, and L2-MC (simulated metal-ceramic alloys); 18 metal-ceramic bond strength specimens were prepared in C-MC, L1-MC, and L2-MC groups (n=6). The tensile test and 3-point bend test were conducted using a universal testing machine. The fracture surfaces of the L2-RPD tensile bar were examined using a scanning electron microscope. The Student t test (α=.05) was used for statistical analysis.Results
No significant differences were observed between the bond strengths of L1-MC and C-MC (P=.74) or between those of L2-MC and C-MC (P=.124). The 0.2% yield strength (σ0.2) and elongation of all SLM specimens exceeded the minimum requirements required for the fabrication of thin RPDs as prescribed in ISO 22674:2016. The σ0.2 value of L1-MC and L2-MC was significantly higher than that of C-MC. Significant differences in σ0.2 values were found among the 3 RPD groups, L1-RPD>L2-RPD>C-RPD. For the elongation, significant differences were found among the 3 groups, L2-RPD>C-RPD>L1-RPD. The fracture surface of L2-RPD showed clear submicroscale dimples with fusion defects.Conclusions
When Co-Cr metal copings and RPD frameworks were fabricated on the same substrate simultaneously using SLM, heat treatment at 1100°C was found more suitable than at 880°C to release residual stress, considering the toughness required for dental prostheses. 相似文献2.
3.
王勇 《中华口腔正畸学杂志》2016,(2):102-107
口腔医学数字化技术是指借助数字化硬件或软件辅助口腔医生实现精确、高效、自动、智能的口腔疾病诊断与治疗的技术.“数字化口腔诊疗模式”正在改变着口腔医学的传统诊疗模式,成为口腔医学未来的发展趋势之一.本文简要概述口腔医学数字化技术的临床应用现状,阐述相关重点技术,并针对口腔医学与数字化技术的几点重要关系谈谈个人的思考. 相似文献
4.
Weina Wang Hai Yu Yifan Liu Xinlei Jiang Bo Gao 《The Journal of prosthetic dentistry》2019,121(2):285-291
Statement of problem
The primary manufacturing method of zirconia ceramic crowns is computer-aided design and computer-aided manufacture (CAD-CAM), but a disadvantage of this technique is material waste. Three-dimensional (3D) printing, which has been recently introduced into dentistry, has improved the processing of polymers and metals, but not yet of ceramic crowns.Purpose
The purpose of this in vitro study was to evaluate the 3D trueness of zirconia crowns fabricated by 3D printing to investigate the potential application of this technology in dental ceramic restorations.Material and methods
A typodont tooth was prepared for a ceramic crown, and a digital crown was designed using the CAD software. The digital crown was processed either with a 3D-printing system or with a dental milling system. The crowns were scanned using a dental laboratory scanner, and the data collected for each crown were divided into 4 parts (the external surface, intaglio surface, marginal area, and intaglio occlusal surface). Finally, the trueness of each part was determined using the 3D inspection software. The 3D trueness of the crowns fabricated by either 3D printing or milling was compared by a 1-sided test (α=.05).Results
The trueness of the external surface, intaglio surface, marginal area, and intaglio occlusal surface of the 3D-printed crowns was no worse than the corresponding trueness of the CAD-CAM crowns (P<.05).Conclusions
Zirconia crowns produced by 3D printing meet the trueness requirements, and 3D printing may be suitable for fabricating zirconia crowns. 相似文献5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
J.S. Zheng X.H. Liu X.Z. Chen W.B. Jiang A. Abdelrehem S.Y. Zhang M.J. Chen C. Yang 《International journal of oral and maxillofacial surgery》2019,48(11):1440-1447
Temporomandibular joint (TMJ) lesions, when large and extensive, will often involve skull base destruction and result in extensive resections, requiring a challenging reconstruction. This study introduces a special type of craniomaxillofacial prosthesis for massive combined skull base–TMJ lesions. Patients who presented with combined skull base–TMJ lesions were recruited. Enhanced computed tomography (CT) data were obtained for all patients and transformed into three-dimensional (3D) reconstruction models. The combined skull base–TMJ prosthesis was designed and fabricated with a customized principle by 3D-printing technology. Clinical follow-up and radiographic evaluations were performed to assess the feasibility of the combined prosthesis in clinical application. A series of five consecutive patients were included in this study. No severe complications occurred after surgery. Based on a mean follow-up period of 13.8 months, the preliminary results suggest that the combined prosthesis has a positive impact on clinical outcomes: there was a mean 75.0% reduction in pain, 55.6% improvement in diet, 54.5% improvement in mandibular function, and 33.6% increase in mouth opening, with significant differences when compared with the preoperative state (all P < 0.05). This study suggests that the combined prosthesis represents a safe and reliable implantable reconstruction method for combined skull base–TMJ lesions. 相似文献
15.
16.
17.
18.
19.
