Title: silver containing glass infiltrations in dental zirconia for improved mechanical and antimicrobial properties

Abstract

The introduction of zirconia in dentistry partly solved the need for better mechanical properties of metal-free protheses. In spite of the high strength, the veneering porcelain on zirconia is brittle and fractures easily. Besides that, zirconia also presents low bond strength to resin cement. Another disadvantage is its low temperature degradation under certain conditions of moisture and temperature. All of these limitations could be improved with a layer of graded silicates (glass) covering the surface and infiltrating the bulk of zirconia, resulting in a functionally graded material (FGM), without sharp variations in the phases and properties. Besides its use in crowns and fixed prostheses, zirconia has been used for abutments, implants and orthodontic appliances, that is, in clinical situations in which the antimicrobial properties are desirable. Thus, this study aims to make a compound material of zirconia infiltrated with silicium, aluminum, sodium, potassium and calcium. It also aims to create a glass of similar composition including silver in it (5%) and test the antimicrobial properties and cell viability with the counting of colony forming units and cito and cenotoxicity assays. The glass will be applied manually with a brush on the pre-sintered zirconia specimens, which will be heated for interdiffusion of phases, until forming a functionally graded material. The silver containing glass will applied on previously sintered zirconia specimens, purely (5%) or mixed with glazing poder to reduce the silver concentration (4%). To combine the effects of a functionally graded material and antimicrobial properties, the silver containing glass will also applied on zirconia previously infiltrated with glass. The flexural strenght (ISO 6872-2015), hardness, fracture troughness, structural reliability, translucency and free energy of infiltrated and control zirconias will be measured. For the structural analysis, the specimens will be evaluated with X-ray diffraction, Raman specroscopy, and scanning electron microscope. After exploratory analysis of data and followed the normality assumptions, the data will be submitted to statistical analysis, with a significance level (±) of 5% for all tests. (AU)