Optimization of surface roughness, phase transformation and shear bond strength in sandblasting process of YTZP using statistical machine learning.

Sandblasting process is often applied to roughen the intaglio of yttria tetragonal zirconia polycrystals (YTZP) surfaces for easy and quality adhesion and micro-shear retention with dentine/resin cements. Sandblasting process parameters have shown to influence, at different scales, surface roughness, phase transformation and shear bond strength, all of which are referred, herein, as performance characteristics. This study aimed to find the parametric settings of sandblasting parameters that could simultaneously optimize these performance characteristics, hypothetically testing the probability.

Investigation of indentation size effect and R-curve behaviour of LiO-SiO and LiO-2SiO glass ceramics.

Indentation size effect (ISE) and R-curve behaviour of LiO-SiO and LiO-2SiO glass ceramics are investigated using micro-indentation and indentation-strength (IS) techniques, respectively. Vickers micro-indentations were applied on both materials at the load of 0.10-19.

Influence of CAD/CAM milling, sintering and surface treatments on the fatigue behavior of lithium disilicate glass ceramic.

This paper reports on the process-fatigue relation of lithium disilicate glass ceramic (LDGC) using low-cycle, high-load Hertzian indentations with a rigid indenter to simulate teeth grinding/clenching of LDGC restorations with different surface asperities obtained in CAD/CAM milling, sintering, polishing and glazing. The maximum contact stresses were evaluated as functions of the number of load cycles and surface treatments using the Hertzian model. Indentation-induced surface damage was viewed using scanning electron microscopy (SEM) to understand the relationships among microstructures, surface asperities, crack morphology and propagation.

Elasticity, plasticity and analytical machinability prediction of lithium metasilicate/disilicate glass ceramics.

This paper applied non-linear theory of elasticity (NLTE) to partition indentation-induced deformations into elasticity and plasticity for lithium metasilicate glass ceramic (LMGC), sintered and pressed lithium disilicate glass ceramics (SLDGC and PLDGC). It also used elastic plastic fracture mechanics (EPFM) approach to analytically predict machinability for these materials. Using the Sakai's series elastic and plastic deformation model that applied NLTE, the resistances to plasticity for LMGC, SLDGC and PLDGC were extracted from their respective indentation-extracted plane strain moduli and contact hardness values.

A review of engineered zirconia surfaces in biomedical applications.

Zirconia is widely used for load-bearing functional structures in medicine and dentistry. The quality of engineered zirconia surfaces determines not only the fracture and fatigue behaviour but also the low temperature degradation (ageing sensitivity), bacterial colonization and bonding strength of zirconia devices. This paper reviews the current manufacturing techniques for fabrication of zirconia surfaces in biomedical applications, particularly, in tooth and joint replacements, and influences of the zirconia surface quality on their functional behaviours.

Fracture, roughness and phase transformation in CAD/CAM milling and subsequent surface treatments of lithium metasilicate/disilicate glass-ceramics.

This paper studied surface fracture, roughness and morphology, phase transformations, and material removal mechanisms of lithium metasilicate/disilicate glass ceramics (LMGC/LDGC) in CAD/CAM-milling and subsequent surface treatments. LMGC (IPS e.max CAD) blocks were milled using a chairside dental CAD/CAM milling unit and then treated in sintering, polishing and glazing processes.

Surface quality of yttria-stabilized tetragonal zirconia polycrystal in CAD/CAM milling, sintering, polishing and sandblasting processes.

This paper studied the surface quality (damage, morphology, and phase transformation) of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in CAD/CAM milling, and subsequent polishing, sintering and sandblasting processes applied in dental restorations. X-ray diffraction and scanning electron microscopy (SEM) were used to scan all processed surfaces to determine phase transformations and analyse surface damage morphology, respectively. The average surface roughness (R) and maximum roughness (R) for all processed surfaces were measured using desk-top SEM-assisted morphology analytical software.

Nano-mechanical behaviour of lithium metasilicate glass-ceramic.

This paper reports the first study on the mechanical behavior of lithium metasilicate glass-ceramic using nanoindentation and in situ scanning probe imaging techniques. Indentation contact hardness, Hc, and Young's modulus, E, were measured at 10 mN peak load and 0.1-2 mN/s loading rates to understand the loading rate effect on its properties.

Nano-scale mechanical properties and behavior of pre-sintered zirconia.

This paper reports on the mechanical properties and material behavior of pre-sintered zirconia using nanoindentation with in situ scanning probe microscopy. Indentation contact hardness, Hc, and Young׳s modulus, E, were measured at loading rates of 0.1-2mN/s and 10mN peak load to understand the loading rate effect on its properties.