Characterization of a Diamond Ground Y-TZP and Reversion of the Tetragonal to Monoclinic Transformation

Author(s)

Candido, L. M. ; Fais, L. M. G. ; Ferreira, E. B. ; Antonio, S. G. ; Pinelli, L. A. P.

• Document type: Journal article
• Source: Operative Dentistry; v. 42, n. 4, p. 407-417, JUL-AUG 2017.
• Web of Science Citations: 2

Abstract

Purpose: To characterize the surface of an yttria-stabilized zirconia (Y-TZP) ceramic after diamond grinding in terms of its crystalline phase, morphology, mean roughness (Ra), and wettability as well as to determine a thermal treatment to reverse the resulting tetragonal to monoclinic (t-m) transformation. Methods and Materials: Y-TZP specimens were distributed into different groups according to the actions (or no action) of grinding and irrigation. Grinding was accomplished using a diamond stone at a low speed. The samples were characterized by x-ray diffraction (XRD), scanning electron microscopy, goniometry, and profilometry. In situ high-temperature XRD was used to determine an annealing temperature to reverse the t-m transformation. Ra was submitted to the Kruskal-Wallis test, followed by the Dunn test (alpha=0.05). The volume fraction of the monoclinic phase and contact angle were submitted to one-way analysis of variance, followed by the Tukey test (alpha=0.05). Results: Monoclinic zirconia was observed on the surface of samples after dry and wet grinding with a diamond stone. The volume fraction of the monoclinic phase was smaller on the dry ground samples (3.6%+/- 60.3%) than on the wet ground samples (5.6%+/- 60.3%). Hightemperature XRD showed reversion of the t-m phase transformation, which started at 700 degrees C and completed at 800 degrees C in a conventional oven. Conclusions: Grinding with a diamond stone partially transformed the crystalline phase on the surface of a Y-TZP ceramic from tetragonal to monoclinic zirconia while simultaneously increasing the surface roughness and wettability. The t-m transformation could be reversed by heat treatment at 800 degrees C or 900 degrees C for 60 minutes or 1000 degrees C for 30 minutes. (AU)

• FAPESP's process: 15/04552-3 - Effect of annealing after grinding on different systems of Y-TZP zirconia
• Grantee: Ligia Antunes Pereira Pinelli
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
• Grantee: Edgar Dutra Zanotto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC