A proposal of thermal etching protocol on intergranular regions of dental zirconia

Paula Nunes Guimarães Paes, Hélio Rodrigues Sampaio Filho, Paula Mendes Jardim

Objective: To analyze the topography and microstructure surface parameters of 3Y-TZP after different thermal treatments that aims to reach a zirconia grain boundary as close as possible to its thermodynamic equilibrium geometry, with higher surface energy state. Methods: 3Y-TZP surface was polished and then thermally treated at 1350°C for 10 minutes, as a means of standardizing the roughness. After this, different thermal treatments were carried out. The control group (G1) received no further treatment, Group 2 (G2) was submitted to 750°C for 3 minutes and Group 3 (G3) at 1350°C for one hour. After the treatments, the zirconia surface was analyzed by Atomic Force Microscopy (AFM) and X-ray diffraction (XRD). Results: G3 was the only that promoted increase in surface roughness by enlargement of the groove region. No heat treatment resulted in phase transformation — all samples remained with the same monoclinic phase content (around 4% by weight) — or grain size increase (average grain size ~ 300 nm). Conclusions: The present study demonstrated that G3 treatment is best suited to achieve thermal equilibrium geometry. With the addition of G3, the zirconia reached the higher surface energy state with the intergranular regions more evidenced. That is the ideal surface for future studies that aim to chemically or physically alter 3Y-TZP and promote adhesion to dental resin cements. Additionally, the results confirm that the temperature (750°C) used for the application of glazes and porcelain do not alter the topography and microstructure parameters of the 3Y-TZP surface.

Keywords: Ceramics. Microscopy, atomic force. Thermic treatment. X-ray diffraction. Dental materials.

How to cite: Paes PNG, Sampaio Filho HR, Jardim PM. A proposal of thermal etching protocol on intergranular regions of dental zirconia. J Clin Dent Res. 2019 Jan-Apr;16(1):148-59. DOI: https://doi.org/10.14436/2447-911x.16.1.148-159.oar

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