Effect of different surface treatments on surface roughness, phase transformation, and biaxial flexural strength of dental zirconia.

Niknaz Yahyazadehfar,Sayed Shojaedin Shayegh,Tabassom Hooshmand,Maryam Azimi Zavaree,Mobin Yahyazadehfar,Seyed Mohammad Reza Hakimaneh

doi:10.34172/joddd.2021.035

Abstract

Background. Interfacial failures at the cement‒restoration interface highlights the importance of effective surface treatment with no adverse effect on the zirconia’s mechanical properties. This study aimed to determine the effect of different surface treatments on dental graded zirconia’s surface roughness and certain mechanical properties. Methods. Forty sintered zirconia specimens were randomly divided into four groups (n=10): control (no surface treatment), sandblasting (SA), grinding with diamond bur (GB), and Er,Cr:YSGG laser (LS). Following surface treatment, the surface roughness and surface topography of the specimens were examined. X-ray diffraction (XRD) was conducted. In addition, the biaxial flexural strengths of specimens were evaluated. The data were analyzed using one-way analysis of variance (ANOVA) and post hoc Tukey tests; the Pearson correlation coefficient was calculated between either volumetric percentage of monoclinic phase or roughness and flexural strength of specimens (α=0.05). Results. The GB group exhibited significantly greater surface roughness compared to the other groups (P < 0.005). The LS and control groups exhibited a significantly lower volumetric percentage of the monoclinic phase (P < 0.001) than the GB and SA treatments. The SA group exhibited significantly higher flexural strength than the control (P = 0.02) and GB groups (P < 0.01). Furthermore, the Weibull analysis for the LS showed higher reliability for the flexural strength than other treatments. Conclusion. Er,Cr:YSGG laser treatment, with the lowest extent of phase transformation and reliable flexural strength, can be a promising choice for surface treatment of zirconia.

Highlights

The increasing esthetic needs in dentistry have led to a focus on natural-appearing ceramic restorations
Concerning the surface roughness and topography, the results showed that the mean Ra and Rz values for the specimens ground with a diamond bur (GB group) were significantly higher than the corresponding values in other groups (P < 0.005)
Recent studies showed quite different outcomes on the effectiveness of different surface treatments on zirconia,[16,17,18,33,34,35,36] In a study by Martins et al,[16] the laser treatment resulted in more surface roughness than sandblasting, and the control group exhibited the least extent of roughness

Summary

Introduction

The increasing esthetic needs in dentistry have led to a focus on natural-appearing ceramic restorations In this regard, the stabilized tetragonal zirconia (Y-TZP) exhibits some superiority over other ceramic types with improved mechanical properties, biocompatibility, and esthetic characteristics.[1,2,3,4,5] This introduction explains numerous benefits, including superior mechanical properties, compared to the monolithic lithium disilicate ceramics and manufacturing thinner restorations for more conservative dental preparations.[6] This would lead to the possibility of new standardization and cost reduction due to the CAD-CAM processing technique.[6] Y-TZP zirconia has a unique characteristic that can transform from tetragonal to monolithic phase under mechanical stresses, resulting in extra toughness and strength and hindering crack propagation by 3%‒5%. Er,Cr:YSGG laser treatment, with the lowest extent of phase transformation and reliable flexural strength, can be a promising choice for surface treatment of zirconia

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Methods

Results

Discussion

Conclusion