共查询到20条相似文献，搜索用时 15 毫秒
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Naichuan Su Yunmao Liao Hai Zhang Li Yue Xiaowen Lu Jiefei Shen Hang Wang 《The Journal of prosthetic dentistry》2017,117(1):150-157
Statement of problem
Indirect composite resins (ICR) are promising alternatives as veneering materials for zirconia frameworks. The effects of core-to-dentin thickness ratio (C/Dtr) on the mechanical property of bilayered veneer ICR/yttria-tetragonal zirconia polycrystalline (Y-TZP) core disks have not been previously studied.Purpose
The purpose of this in vitro study was to assess the effects of C/Dtr on the biaxial flexural strength, reliability, and fracture mode of bilayered veneer ICR/ Y-TZP core disks.Material and methods
A total of 180 bilayered 0.6-mm-thick composite resin disks in core material and C/Dtr of 2:1, 1:1, and 1:2 were tested with either core material placed up or placed down for piston-on-3-ball biaxial flexural strength. The mean biaxial flexural strength, Weibull modulus, and fracture mode were measured to evaluate the variation trend of the biaxial flexural strength, reliability, and fracture mode of the bilayered disks with various C/Dtr. One-way analysis of variance (ANOVA) and chi-square tests were used to evaluate the variation tendency of fracture mode with the C/Dtr or material placed down during testing (α=.05). Light microscopy was used to identify the fracture mode.Results
The mean biaxial flexural strength and reliability improved with the increase in C/Dtr when specimens were tested with the core material either up and down, and depended on the materials that were placed down during testing. The rates of delamination, Hertzian cone cracks, subcritical radial cracks, and number of fracture fragments partially depended on the C/Dtr and the materials that were placed down during testing.Conclusion
The biaxial flexural strength, reliability, and fracture mode in bilayered structures of Y-TZP core and veneer ICR depend on both the C/Dtr and the material that was placed down during testing. 相似文献3.
For a patient with a unilateral orbital defect, an esthetic orbital prosthesis plays an essential role in enhancing quality of life. This technique describes the combined use of a facial scanner and an intraoral scanner to acquire the digital scan for the design and fabrication of an orbital prosthesis. The method results in an esthetic prosthesis with accurate skin texture reproduction. 相似文献
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An appliance was designed and fabricated by using computer-aided design and computer-aided manufacturing (CAD-CAM) and 3-dimensional (3D) printing to combine a custom tray with an intraoral Gothic arch. This helped simplify centric relation recording and combined definitive impression making and centric relation recording into a single step. 相似文献
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Yanning Chen Chenmin Yao Cui Huang Yake Wang 《The Journal of prosthetic dentistry》2019,121(3):549.e1-549.e7
Statement of problem
Although newly developed photoinitiators can make up for the limitations of camphorquinone, their absorption spectra are different. However, little attention has been paid to the compatibility of available wavelength spectra of light-polymerization units (LPUs) and photoinitiators within resin cements.Purpose
The purpose of this in vitro study was to evaluate the effect of monowave and polywave light-emitting diode (LED) units on the adhesion of dual-polymerizing self-adhesive resin cements to monolithic zirconia.Material and methods
Monowave LPUs and polywave LPUs were chosen to polymerize 2 dual-polymerizing self-adhesive resin cements. Ninety-six zirconia disks were randomly divided into 4 groups as different combinations of LPUs and resin cements, namely ES-U200, BS-U200, ES-SC, and BS-SC. Resin cements were adhered to zirconia disks, and the microshear bond strength (μSBS) test was conducted after 24 hours of H2O storage (24 h) and 10?000 thermocycles (10k/TC). Failure modes were examined by stereomicroscopy and scanning electron microscopy (SEM). The degree of conversion (DC) was tested both immediately and 24 hours later. In statistical analyses, 2-way ANOVA and the Tukey honestly significant difference post hoc test were performed for μSBS and DC results, and chi-square test was performed for failure mode analysis (α=.05 for all tests).Results
The 2-way ANOVA demonstrated that different combinations of LPUs and resin cements, as well as different artificial aging levels, significantly influenced microshear bond strength values (P<.001). The interactions between 2 factors were also significant (P<.001). The BS-SC group possessed relatively high bond strength in both 24-hour and 10k/TC aging levels. For the same resin cement, no significant difference was found in the immediate DC (P=.405 for U200 and P=.708 for SC). At 24 hours, DC and BS-U200 values were significantly higher than ES-U200 values (P=.002), whereas BS-SC values were not significantly different from ES-SC values (P=.284).Conclusions
Within the limitation of this in vitro study, the emission spectra of LED units significantly influenced the bond strengths, DC, and failure mode of dual-polymerizing self-adhesive resin cements to zirconia at both immediate and artificial aging levels. The LPU should provide light energy to match the absorption wavelengths of photoinitiators in the resin cements. 相似文献8.
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Statement of problem
Selective laser melting (SLM) has become popular in prosthetic dentistry. However, only limited information is available for the internal adaptation of cobalt-chromium (Co-Cr) posts fabricated by SLM.Purpose
The purpose of this in vitro study was to investigate the internal adaptation of Co-Cr metal posts fabricated by SLM technique.Material and methods
Thirty-six Co-Cr metal posts were fabricated by conventional casting, subtractive computer-aided design and computer-aided manufacturing (CAD-CAM), and additive CAD-CAM, by making an impression from a standardized model of a tooth with a single root canal. Posts and the dies were bonded with cement. Specimens were then sectioned horizontally by using a grinding and polishing machine, and 3 different cross-sections of each post were chosen to represent the apical, middle, and coronal regions. The areas of cement were photographed by using a stereomicroscope at an original magnification of ×32 and measured using image-measuring software. From each group, 1 specimen was randomly selected and observed by using scanning electron microscopy. One-way ANOVA and Tukey honestly significant difference test were performed to identify differences among groups with regard to internal adaptation (α=.05).Result
The internal adaptation of the SLM group did not differ from that of the CAD-CAM milling group at 3 cross-section levels (P>.05). At the apical and coronal cross-section levels, the cement area of SLM group was smaller than that of the cast group (P<.05). However, at the middle cross-section level, the cement area of the cast group was significantly smaller than that of the SLM group (P<.05). Use of scanning electron microscopy showed both the SLM group and the CAD-CAM milling group exhibited homogeneous microstructures. However, the cast group showed a typical discontinuous dendritic solidification microstructure.Conclusions
The internal adaptation of SLM was not inferior to that of the CAD-CAM milling group or the cast group. The SLM technique seems a promising choice for fabricating dental posts. 相似文献10.
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Wenbin Yang Wei Liu Cheng Miao Haibin Sun Longjiang Li Chunjie Li 《Journal of oral and maxillofacial surgery》2018,76(10):2066-2073
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