JOINT STRENGTH FOR PIGMENTATION AND GLAZE REPAIR IN HYBRID CERAMIC: effects of different surface treatments

• Grant number: 22/01016-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2022
• End date: July 31, 2023
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Renata Marques de Melo Marinho
• Grantee: Luisa Almeida Passarelli
• Host Institution: Instituto de Ciência e Tecnologia (ICT). Universidade Estadual Paulista (UNESP). Campus de São José dos Campos. São José dos Campos , SP, Brazil

Abstract

Over the years, dentists have opted for the use of ceramics, knowing that they can provide highly esthetic rehabilitations. Hybrid ceramic is a type of ceramic combined with composite resin, made from CAD/CAM technology, being advantageous for the dentist in a way of easy to adapt and/or modify, having a modulus of elasticity similar to the resilient modulus of the dentin. The application of stain and glaze in this type of ceramic is a light cured procedure, but it is known that over time the stain layer can be lost and/or worn out. Thus, this study will evaluate the bond strength and the effects obtained in the hybrid ceramic from different surface treatments and reapplication of glaze and stain. Initially, the hybrid ceramic blocks will be cut, polished and will undergo a bath of distilled water and ultrasound. Then, each specimen will receive a surface treatment with 5% hydrofluoric acid for 60 seconds, also going through washing, drying and silanization. Subsequently, the specimens will be aged using a brushing machine, so that the entire characterization layer (stain + glaze) is removed. After wearing out, the specimens will be socked in artificial saliva for 1 week and will be cleaned, after which they will be randomly divided into 4 groups. Each group corresponds to a different surface reconditioning method to which the specimens will be submitted (rinsing with water; self-etching ceramic primer; hydrofluoric acid and aluminum oxide). After the reconditioning, the specimens will undergo silanization, and stain and glaze will be applied in micro tubes, then light cured. The micro shear test will be made with an universal machine for EMIC mechanical tests, with a load cell of 50 Kgf and 1 mm / min and steel wire (Ø 0.2 mm) will be used in the form of a loop. The maximum load supported until cylinder displacement by each group will be recorded in Newton (N), values will be divided by the bond area and converted to Mega Pascal (MPa). The samples will be stored and analyzed under a stereomicroscope to classify the type of failure. Representative samples will be analyzed in a scanning electron microscope (SEM). The data will be evaluated regarding the assumptions of normality and homoscedasticity to be submitted to the most appropriate statistical tests.Keywords: Hybrid ceramic. Surface reconditioning. Bond strength.