Evaluation and characterization of zirconia surface after treatment with different air-abrasion particles: pilot study

Trabalho final do 5º ano com vista à atribuição do grau de mestre no âmbito do ciclo de estudos de Mestrado Integrado em Medicina Dentária apresentado à Faculdade de Medicina da Universidade de Coimbra.Objective: The aim of the present pilot study was to assess the effect of sandblasting angulations, new air abrasion powder containing zirconia, and cleaning procedure on Y-TZP ceramic surface. Materials and Methods: A total of 4 cylindrical zirconia ceramic disks were divided in 6 different surface treatment groups and for each group 2 samples (n=2) were prepared: group 1 sandblasted with 50μm alumina powder and a 90° angulation; group 2 sandblasted with 50μm alumina powder and a 30° angulation; group 3 sandblasted with 30μm silica-coated alumina and a 90° angulation; group 4 sandblasted with 30μm silica-coated alumina and a 30° angulation; group 5 sandblasted with 82μm zirconia and alumina and a 90° angulation; group 6 sandblasted with 82μm zirconia and alumina and a 30° angulation. Surface roughness (Alicona InfiniteFocus® optical 3-dimensional micro coordinate system), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis were performed in all samples, before and after cleaning procedures with 9,6% hydrofluoric acid and 37% phosphoric acid. Results: Group 1 had the highest roughness values. Samples sandblasted with 30μm silica-coated alumina and with 82μm alumina and zirconia particles showed higher values of roughness in 30º air abrasion than in 90º procedures, after cleaning protocols. EDS analysis confirmed the presence of silica in zirconia surfaces that were sandblasted with silica-coated alumina particles, even after cleaning protocols. The roughness in all samples presented a decreased after cleaning procedures, indicating the presence of smear-layer, contaminants and dust. Results suggested that the experimental 82μm alumina and zirconia abrasive might produce an appropriate roughness, without leaving a great amount of dust after the air abrasion protocol. Conclusions: In accordance with the goal of this pilot study, results showed that powder composition, air-abrasion angulation and cleaning procedures are crucial in the quality and quantity of zirconia surface roughness. Despite of this, further studies are needed to fully understand zirconia surface behaviour to roughening procedures, and to perform adhesion tests, once they are the reason of this basic procedure