| 1. |
- Liu, Jingyin, et al.
(författare)
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Biomineralization stimulated peri-titanium implants prepared by selective laser melting
- 2015
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Ingår i: Journal of Materiomics. - : Elsevier BV. - 2352-8478 .- 2352-8486. ; 1:3, s. 253-261
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Tidskriftsartikel (refereegranskat)abstract
- Titanium implants prepared by selective laser melting (SLM), a method of additive manufacturing, were subjected to implantation in beagle dogs for two and four weeks. Argon ion beam-polished cross sections of the implants after in vivo tests were characterized by scanning electron microscope (SEM) to evaluate the bone–implant interface and the early peri-implant biomineralization with sufficiently improved resolution. Two bone mineralization mechanisms were disclosed. As early as two weeks after implantation, a layer of new bone was found to form directly on the implant surface and bone in-growth was also observed. Osseointegration was found to establish partly at the tip of the implants. After healing for four weeks it was found that osseointegration was established around the entire tip of the implants, whereas only partly at the third thread region of the implants. The experimental evidences observed reveal that an inherent highly porous surface of the titanium implants generated by selective laser melting is favorable for new bone apposition.
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| 2. |
- Liu, Yihong, et al.
(författare)
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Failure Modes and Fracture Origins of Porcelain Veneers on Bilayer Dental Crowns
- 2014
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Ingår i: International Journal of Prosthodontics. - : Quintessence Publishing. - 0893-2174 .- 1139-9791. ; 27:2, s. 147-150
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were to determine the fracture origins and crack paths in the porcelain of clinically failed bilayer ceramic restorations and to reveal the correlation between the porcelain failures and material properties. Three clinically failed crowns of each material (bilayer zirconia crowns, galvano-ceramic crowns, and porcelain-fused-to-metal crowns) were collected and underwent failure analysis. The fractures found in porcelain veneers showed several characteristics including wear, Hertzian cone crack, chipping off, and delamination. The results indicated that the fracture origins and features of the porcelain in bilayer ceramic restorations might be affected by the rigidity of core materials and thickness of copings.
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| 3. |
- Liu, Yihong, et al.
(författare)
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Fracture and interfacial delamination origins of bilayer ceramic composites for dental restorations
- 2010
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 30:6, s. 1297-1305
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Tidskriftsartikel (refereegranskat)abstract
- Alumina and zirconia (Y-TZP) based bilayer ceramic dental composites with core to veneer thickness ratio (R-value) of 1: 1 and 2:1 were fabricated through an established dental laboratory multi-steps-firing procedure. Their flexural strengths were determined by three-point bending test. A combinational approach of numerical simulations by finite element analysis associated with direct fractography investigation was applied to elucidate the origins of fracture and interfacial delamination and the influence of physical properties mismatch between core ceramic and veneer porcelain. A newly developed argon ion beam cross-section polishing technique was used to conduct fine polishing required for close investigating of the core-veneer interface under scanning electron microscope. For the same core ceramic no significant difference was observed in determined flexural strength of two groups of bilayer composites. The flexural strength of the bilayer composites is similar to 55% and similar to 35% of the core ceramics and achieved similar to 90% and 70-77% of the predicated value respectively in case of Y-TZP and alumina based composites. Numerical simulations by finite element analysis indicate that the often observed interfacial delamination in Y-TZP based bilayer composites has a clear origin of the severe physical properties mismatch between veneer porcelain and core ceramics, particularly the flexural strength, which may be prevented by increasing the flexural strength of veneer porcelain to above 300 MPa. The observation of the formation of microcracks in alumina core immediately one grain-thick under the veneer-core interface warns the possible thermal damages initiated during the veneering operation.
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