Viritpon Srimaneepong

Improving shear bond strength between feldspathic porcelain and zirconia substructure with lithium disilicate glass-ceramic liner.

This study investigated the shear bond strength (SBS) between veneering porcelain and zirconia substructure using lithium disilicate glass-ceramic as a liner. The mineral phases and microstructures of lithium disilicate glass-ceramic at temperature range of 800-900°C were preliminarily investigated. SBSs of porcelain-veneered zirconia specimens with and without lithium disilicate glassceramic liner fired at the same temperature were determined. Results showed that SBSs of veneering porcelain and zirconia with lithium disilicate glass-ceramic liner was notably increased (p<0.05). Specimens from the group with the highest SBS (59.7 MPa) were subject to thermocycling up to 10,000 cycles and their post-thermocycling SBSs investigated. Though weakened by thermocycling, SBSs were above the clinically acceptable limit (25 MPa) of ISO 9693. Fractographic analysis revealed mixed cohesive and adhesive failures. It was concluded that lithium disilicate glass-ceramic is a potential liner which generated high SBS between veneering porcelain and zirconia.

Effects of Surface Roughness and Chemical Species on Hydrophilicity of Anodized Film on Ti-6Al-4V Formed at a Low Current Density

Anodization of Ti-6Al-4V is crucial for dental implants because it promotes the roughness, chemical species and hydrophilicity of the surface that leads to its biocompatibility. The anodized film was prepared by the galvanostatic method at a low current density in either 1 M H3PO4 or 1 M NaOH as the electrolyte. The as-anodized film showed a significant decrease in the water contact angle, likely to be due to an increased surface roughness (as revealed by scanning electron and atomic force microcopy) and change in the surface species (as revealed by X-ray photoelectron spectroscopy, XPS). XPS analyses confirmed that the Ti2p spectra scarcely changed while the O1s spectra significantly changed due to Ti-OH bonding. Moreover, the O/Ti ratio of the as-anodized film was increased. The results suggest that anodization by the galvanostatic method at a low current density in 1 M H3PO4 or 1 M NaOH could enhance the surface roughness and chemical surface species, and that both are likely to be important factors for enhancing the hydrophilicity of the anodized films.

Micromorphology of Porosity Related to Electrical Resistance of Dental Luting Cements

The aim was to investigate the relation between micromorphology of porosity and electrical resistance of dental luting cements. Five dental luting cements were evaluated: zinc phosphate, glass ionomer, and three types of resin luting cements. Porosity of the specimen was analyzed by micro-CT and electrical resistance of cement was measured at voltage of 125 V up to 30 days and solubility of each specimen was calculated. It showed that the resin luting cements provided the highest electrical resistance regardless of amount of porosity. Zinc phosphate and glass ionomer had high porosity and the lowest resistance (14 and 3 kΩ, respectively). It was found that the electrical resistance of luting cement was not directly affected by the amount of porosity, but it seems to be related to pore connection. There is no correlation between electrical resistance and percentage of porosity but the morphology of porosity may have an influence on the electrical property of luting cement. Models of pore connection were proposed to explain the electrical resistance of luting cement.

Polymeric materials and films in dentistry: An overview

Graphical abstract

Surface Characteristics and Hydrophilicity of the as-Anodized Films Formed at High Current Density on Ti-6Al-4V in Different Electrolytes

Hydrophilicity of the as-anodized films is an important factor for improving the osseointegration of Ti implants and bone tissues. This study investigated the surface characteristics and the hydrophilicity of the as-anodized films formed on Ti-6Al-4V. The as-anodized films on Ti-6Al-4V were prepared using galvanostatic method in 1M H3PO4 or 1M MCPM as an electrolyte with different current densities (5, 20, 80 mA/cm2) and using potentiostatic method with different voltages (5, 100 and 150 V) for 30 minute at room temperature. The as-anodized films shows a significantly lower water contact angle compared to the untreated Ti-6Al-4V. The porous oxide films were fabricated on Ti-6Al-4V. Ti 2p spectra show that the as anodized films consist of TiO2 and O 1s present hydroxide (OH-) and adsorbed water (H2O) that effect to the hydrophilicity on the as-anodized film surface. These results demonstrate that the galvanostatic method at a high current density of 20 mA/cm2 and the potentiostatic at a high voltage of 150 V in MCPM could enhance both of the high surface roughness and appropriate surface species which is leading to good hydrophilicity on the as-anodized films.