Tianwen Guo

Effect of Surface Modifications on the Bonding Strength of Titanium–Porcelain

Investigations of surface modifications on cast titanium surfaces and titanium–porcelain adhesion were performed. Cast pure titanium was subjected to surface modifications by sandblasting, preoxidation, and SnO x coating by sol-gel process. The adhesion between the titanium and porcelain was evaluated by a three-point flexure bonding test. The X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) results revealed that failure of the titanium–porcelain predominantly occurred at the titanium–oxide interface after sandblasting and preoxidation treatments. The SnO x film with small spherical pores obtained at 300°C served as an effective oxygen diffusion barrier and improved titanium–porcelain adhesion. With the temperature elevated, SnO was oxidized to SnO2 and the film microcracked, which resulted in the decrease of the titanium–porcelain bonding strength.

Preparation and characterization of a titanium bonding porcelain

The titanium bonding porcelain was synthesized through normal melting-derived route using borate-silicate system. The porcelain was characterized by thermal expansion, X-ray diffraction, scanning electron microscope and cytotoxicity tests. The results of X-ray diffraction showed that the main phase of the bonding porcelain was SnO2. The SnO2 microcrystals precipitated from the glass matrix when the SnO2 content was increased. The thermal expansion coefficient of bonding porcelains decreased with the increasing concentration of SiO2. The thermal expansion coefficient of bonding porcelains first decreased slightly with the increasing of B2O3 concentration (from 0 wt% to 10 wt%) and then increased to about 9.4×10(-6)/°C(from 10 wt% to 12 wt%). As an intermediate, B2O3 can act as both network formers and modifiers, depending on the relationship between the concentration of basic oxides and intermediates. The Vickers hardness of bonding porcelains increased with the increase of SnO2 concentration. When SnO2 concentration was 6 wt%, only Si and Sn elements attended the reaction between titanium and porcelain and mainly adhesive fracture was found at Ti-porcelain interface. When SnO2 concentration was 12 wt%, failure of the titanium-porcelain predominantly occurred in the bonding porcelain and mainly cohesive fracture was found at Ti-porcelain interface. The methyl thiazolyl tetrazolium assay results demonstrated that the cytotoxicity of the titanium porcelain was ranked as 0.

Synthesis and Characterization of SiO2 Coating on Cast Pure Titanium

The silicon coating was deposited by sol–gel dipping process as intermediate layer to minimize titanium oxidation for Ti-porcelain restorations. The effect of silicon coating on bonding strength of titanium–porcelain was investigated. The adhesion between the titanium and porcelain was evaluated by three-point flexure bonding test. The result of TG-DSC analysis showed that the optimal treating temperature for SiO2 coating was 300°C. Silicon coating was effective in preventing titanium oxide layer formation and improving bonding strength. The improvement in bonding strength of titanium–porcelain was about 10%. At the same time, the in vitro bioactivity of the titanium and SiO2 coating was studied by cytotoxicity test. The methyl thiazolyl tetrazolium assay results demonstrated that the cytotoxicities of SiO2 coating were ranked as 0. The SEM results revealed the existence of microcrack on the SiO2 coating surface. Failure of the titanium–porcelain predominantly occurred at the titanium-oxide interface. The SiO2 coating increased bonding strength of titanium–porcelain and could be used for dental implant materials.

Influence of particle size distribution of dental opacifier on the color of titanium opaque porcelain

OBJECTIVE To investigate the effect of particle size distribution of opacifier tin dioxides (SnO(2)) on the color of dental opaque porcelain for pure titanium by spectrophotometer. METHODS Sixteen groups of opaque porcelain powders were prepared by combining four grain size SnO(2) with four pigments (no pigment, yellow, coral pink and grey). Five porcelain discs (13 mm diameter and 2mm thickness) for each powder were fired. K/S ratios and L*a*b* values of specimens were obtained by a spectrophotometer. The maximum color differences (ΔE(max)) caused by grain size of SnO(2) in each pigment group were determined using the CIELAB and the CIEDE2000 formulas. The L*a*b* values in each pigment group were compared by MANOVA and the ΔE(max) of different pigment groups were subjected to one way ANOVA. RESULTS With SnO(2) grain size increasing, the L* values decreased, and both a* and b* became more chromatic consistently in each pigment group (p<0.001). The ΔE(max) in all pigmented groups were above the 50:50% perceptibility thresholds, with ΔE(max) in yellow group greater than the acceptability thresholds. Significant difference was found in the ΔE(max) of four pigment groups regardless of the color formula (p<0.001). CONCLUSIONS 15 wt% SnO(2) with median particle size ranging from 0.85 μm to 20.75 μm caused significantly perceptible color differences in the pigmented titanium opaque porcelains used in this study.

Preparation and Characterization of a Titanium Opaque Porcelain

The titanium opaque porcelain was synthesized through normal melting-derived route. The porcelain was characterized by thermal expansion, X-ray diffraction (XRD), and cytotoxicity tests. The results of XRD showed that the main phase of the opaque porcelain was SnO2. The Vickers hardness and flexure strength increased with increasing concentration of SnO2. The thermal expansion coefficient of opaque porcelains decreased with increasing concentration of SnO2 (or decreased with decreasing concentration of SiO2). The one-way ANOVA test indicated that there was no significant difference between the bonding strength of self-made titanium porcelain systems and super porcelain Ti-22. In this research, all measured bonding strengths were higher than 25 MPa (ISO 9693 standard). The methyl thiazolyl tetrazolium assay results demonstrated that the cytotoxicity of the titanium opaque porcelain was ranked as zero.

Effect of SnO–SiO2 composite coating on bonding of titanium–porcelain

Abstract The SnO–SiO2 composite coating was deposited on titanium (Ti) by sol–gel dipping process. The adhesion between the Ti and porcelain was evaluated by three point flexure bonding test. The results of thermogravimetry and differential scanning calorimetry analysis showed that the optimal heat treating temperature for SnO–SiO2 composite coating was 300°C. The SEM results revealed that the existence of microcracks on the SnO–SiO2 composite coatings surface after being treated at 300°C. The Ti oxide was formed along the crack. Failure of the Ti–porcelain predominantly occurred at the SnO–SiO2 composite coatings. SnO–SiO2 composite coatings served as an effective oxygen diffusion barrier, improved the chemical bonding between porcelain and Ti and resulted in the increased bonding strength of Ti–porcelain.

Synthesis and Characterization of Titanium Dentin Porcelain

The titanium dentin porcelain was synthesized through normal melting-derived route using borate-silicate system. The porcelain was characterized by thermal expansion, X-ray diffraction (XRD), and cytotoxicity tests. The results of XRD showed that the dentin porcelain is homogeneous vitreous and without crystalloids. The thermal expansion coefficient of dentin porcelains increased with the increasing concentration of CaO (or decreased with the increasing concentration of SiO2). The methyl thiazolyl tetrazolium assay results demonstrated that the cytotoxicity of the titanium porcelain was ranked as 0. It was believed that the titanium dentin porcelain synthesized in this research was a biocompatible material and could be used for dental implant materials.