Adhesion behavior of conventional and high‐translucent zirconia: Effect of surface conditioning methods and aging using an experimental methodology

Objective: Evaluate the adhesive behavior of conventional and high-translucent zirconia after surface conditioning and hydrothermal aging. Materials and methods: Conventional (ZrC) and high-translucent zirconia (ZrT) specimens were divided into six groups: without surface treatment (ZrC and ZrT), air-borne particle abrasion with 50-μm Al2 O3 sized particles (ZrC-AO and ZrT-AO), and tribochemical treatment with 30-μm silica modified Al2 O3 sized particles (ZrC-T and ZrT-T). Zirconia specimens were treated using an MDP-containing universal adhesive and bonded to two resins blocks with an adhesive luting cement. Microbar specimens with cross-sectioned areas of 1 mm2 were achieved. Half of the microbars were subjected to hydrothermal aging. Bond strength was evaluated by microtensile bond strength test and statistically evaluated by the Weibull analysis. Results: Roughness of the ZrC-AO and ZrT-AO groups were statistically higher. Bond strength analysis revealed higher bond strength for ZrC-AO and ZrC-T groups compared to ZrT-AO and ZrT-T, respectively. Mixed failure was the most frequent for the mechanically treated groups, while no cohesive failures were obtained. Conclusion: Lower values of bond strength were obtained for the mechanically treated high-translucent zirconia groups when compared to their conventional zirconia counterparts. Mechanical surface treatment significantly improved the bond strength to conventional and high-translucent zirconia. Clinical significance: Mechanical surface treatment (air-borne particle abrasion or tribochemical treatment) associated with the use of universal adhesives containing MDP could provide a durable bonding to conventional and high-translucent zirconia. Keywords: adhesive cementation; high-translucent zirconia; microtensile bond strength

Chitosan-based hierarchical scaffolds crosslinked with genipin

Osteochondral defects present significant challenges for effective tissue regeneration due to the complex composition of bone and cartilage. To address this challenge, this study presents the fabrication of hierarchical scaffolds combining chitosan/β-tricalcium phosphate (β-TCP) to simulate a bone-like layer, interconnected with a silk fibroin layer to mimic cartilage, thus replicating the cartilage-like layer to mimic the native osteochondral tissue architecture. The scaffolds were produced by freeze-drying and then crosslinking with genipin. They have a crosslinking degree of up to 24%, which promotes a structural rearrangement and improved connection between the different layers. Micro-CT analysis demonstrated that the structures have distinct porosity values on their top layer (up to 84%), interface (up to 65%), and bottom layer (up to 77%) and are dependent on the concentration of β-tricalcium phosphate used. Both layers were confirmed to be clearly defined by the distribution of the components throughout the constructs, showing adequate mechanical properties for biomedical use. The scaffolds exhibited lower weight loss (up to 7%, 15 days) after enzymatic degradation due to the combined effects of genipin crosslinking and β-TCP incorporation. In vitro studies showed that the constructs supported ATDC5 chondrocyte-like cells and MC3T3 osteoblast-like cells in duo culture conditions, providing a suitable environment for cell adhesion and proliferation for up to 14 days. Overall, the physicochemical properties and biological results of the developed chitosan/β-tricalcium phosphate/silk fibroin bilayered scaffolds suggest that they may be potential candidates for osteochondral tissue strategies.This study was partially financed by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001 and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), PVE 407035/2013-3. This work is also financially supported by Portuguese FCT (PD/BD/135247/2017, SFRH/BPD/93697/2013, DL 57/2016/CP1377/CT0054 (https://doi.org/10.54499/DL57/2016/CP1377/CT0054), CEECINST/00018/2021), PhD programme in Advanced Therapies for Health (PATH) (PD/00169/2013), FCT R&D&I projects with references PTDC/BII-BIO/31570/2017, PTDC/CTM-CTM//29813/2017, and PTDC/CTM-BIO/4706/2014- (POCI-01-0145-FEDER-016716). The authors would like to thank the contributions to this research from the project “TERM RES Hub—Scientific Infrastructure for Tissue Engineering and Regenerative Medicine”, reference PINFRA/22190/2016 (Norte-01-0145-FEDER-022190), funded by the Portuguese National Science Foundation (FCT) in cooperation with the Northern Portugal Regional Coordination and Development Commission (CCDR-N), for providing relevant lab facilities, state-of-the-art equipment, and highly qualified human resources

Colouring of opaque ceramic glaze with zircon pigments: Formulation with simplified Kubelka–Munk model

In this study a simplified Kubelka–Munk model is proposed for colour matching purposes. Opaque glazes were prepared to determine theabsorption optical constants from the reflectance curves measured with a spectrophotometer. After the physical and chemical characterization ofthe glaze components (frit and pigments), to analyze the spectrophotometric results a simplification of the Kubelka–Munk model was suggested.To experimentally verify the model, two target green colour were reproduced in laboratory by adding in an opaque glaze a yellow praseodymiumdopedzircon ((Zr,Pr)SiO4) and blue vanadium-doped zircon ((Zr,V)SiO4) pigments. The results were in good agreement with the experimentalreflectance curves and the prediction of colour green glazes was possible with a reduced number of experiments

Colouring of opaque ceramic glaze with zircon pigments: Formulation with simplified Kubelka–Munk model

In this study a simplified Kubelka–Munk model is proposed for colour matching purposes. Opaque glazes were prepared to determine theabsorption optical constants from the reflectance curves measured with a spectrophotometer. After the physical and chemical characterization ofthe glaze components (frit and pigments), to analyze the spectrophotometric results a simplification of the Kubelka–Munk model was suggested.To experimentally verify the model, two target green colour were reproduced in laboratory by adding in an opaque glaze a yellow praseodymiumdopedzircon ((Zr,Pr)SiO4) and blue vanadium-doped zircon ((Zr,V)SiO4) pigments. The results were in good agreement with the experimentalreflectance curves and the prediction of colour green glazes was possible with a reduced number of experiments

Colouring of opaque ceramic glaze with zircon pigments: Formulation with simplified Kubelka–Munk model

In this study a simplified Kubelka–Munk model is proposed for colour matching purposes. Opaque glazes were prepared to determine theabsorption optical constants from the reflectance curves measured with a spectrophotometer. After the physical and chemical characterization ofthe glaze components (frit and pigments), to analyze the spectrophotometric results a simplification of the Kubelka–Munk model was suggested.To experimentally verify the model, two target green colour were reproduced in laboratory by adding in an opaque glaze a yellow praseodymiumdopedzircon ((Zr,Pr)SiO4) and blue vanadium-doped zircon ((Zr,V)SiO4) pigments. The results were in good agreement with the experimentalreflectance curves and the prediction of colour green glazes was possible with a reduced number of experiments

Prediction of opaque ceramic enamel color using the Kubelka-Munk

In this paper the possibility to predict the color of a ceramic glaze by the Kubelka-Munk theory has been evaluate

Prediction of opaque ceramic enamel color using the Kubelka-Munk

In this paper the possibility to predict the color of a ceramic glaze by the Kubelka-Munk theory has been evaluate

Application of zirconia in dentistry: biologic, mechanical and optical considerations

Aiming to replace the infrastructure of metallic dental prostheses, structural ceramics have been improved and increasingly used in dentistry. Among the dental ceramics, the zirconia has emerged as a versatile and promising material because of its biological, mechanical and optical properties, which has certainly accelerated the routine use of CAD/CAM technology in different types of prosthetic treatment.Routinely, zirconia based ceramics are used in structural applications in engineering as the manufacture of cutting tools, gas sensors, refractories and structural opacifiers. To meet structural demands, zirconia has to be doped with stabilizers to achieve high strength and fracture toughness. The bioceramics nowadays, used in medical and dental care, derived from structural materials used in aerospace and military armor, which were modified to suit the additional requirements of biocompatibility

Influence of ns-Nd:YAG laser surface treatment on the tensile bond strength of zirconia to resin-matrix cements

The main aim of this study was to assess the effect of ns-Nd:YAG laser structuring over zirconia green compacts on the adhesion of sintered zirconia to resin-matrix cements. Zirconia (3Y-TZP) compacts were divided according to the type of surface modification: GB – alumina grit-blasted sintered specimens; G8L – laser structured zirconia green compacts (square pattern 8 lines); G16L - laser structured zirconia green compacts (square pattern 16 lines); G8L/GB – alumina grit-blasted G8L specimens after sintering. Specimens of same group were cleaned, cemented using a dual cure resin-matrix cement and aged in distilled water for 24 h (37 °C). Afterwards, the tensile bond strength was measured using a universal test machine. Specimens were analyzed by field emission guns scanning electron microscopy (FEGSEM) and white light interferometry (WLI). Laser-structured surfaces showed higher roughness values and improved morphological aspects for adhesion to resin-matrix cements. Higher tensile bond strength mean values of zirconia to resin-matrix cements were recorded for G8L (16.7 ± 3.8 MPa) and G16L (13.6 ± 3.0 MPa) groups when compared to those recorded for ordinary grit-blasted zirconia surfaces to resin-matrix cements (10 ± 3.1 MPa). The highest tensile bond strength results were recorded for the G8L/GB group (24.2 ± 7.6 MPa). The laser texturing of green zirconia surfaces promoted an increase in roughness and changes in morphological aspects of sintered zirconia for improved adhesion to resin-matrix cements