Effect of Finishing Protocols on the Surface Roughness and Fatigue Strength of a High-Translucent Zirconia

Larissa Araújo Lopes Barreto; Manassés Tercio Vieira Grangeiro; Pedro Henrique Condé Oliveira Prado; Marco Antonio Bottino; Amanda Maria de Oliveira Dal Piva; Nathalia de Carvalho Ramos; João Paulo Mendes Tribst; Lafayette Nogueira Junior

doi:10.1155/2023/8882878

Effect of Finishing Protocols on the Surface Roughness and Fatigue Strength of a High-Translucent Zirconia

Int J Dent. 2023 Sep 22:2023:8882878. doi: 10.1155/2023/8882878. eCollection 2023.

Authors

Larissa Araújo Lopes Barreto¹, Manassés Tercio Vieira Grangeiro¹, Pedro Henrique Condé Oliveira Prado¹, Marco Antonio Bottino¹, Amanda Maria de Oliveira Dal Piva², Nathalia de Carvalho Ramos¹, João Paulo Mendes Tribst³, Lafayette Nogueira Junior¹

Affiliations

¹ Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (Unesp), Eng. Francisco José Longo Avenue, 777, São José dos Campos, SP, Brazil.
² Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, Netherlands.
³ Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, Netherlands.

Abstract

Purpose: In case of need for esthetical improvement of zirconia restorations, an individualization using extrinsic staining can be applied. This study aimed to evaluate the surface roughness and fatigue strength (survival) of high-translucency zirconia (3Y-TZP, YZ®HT, Vita Zanhfabrik) with extrinsic characterization and/or glaze.

Methods: Sixty (60) zirconia discs (12 × 1.2 mm) were obtained, sintered, and randomly distributed among three groups (n = 20) according to the surface finishing protocol: C (control), C + G (extrinsic characterization followed by a glaze layer), and G (glaze layer). The surface roughness (Ra) was analyzed with a contact profilometer. Subsequently, the specimens were subjected to a fatigue load profile starting at 120 N during 20,000 cycles at 4 Hz frequency, with a 5% increase at each step until failure. The failed specimens were evaluated under a stereomicroscope. Surface roughness analysis was evaluated by using one-way ANOVA and post hoc Tukey tests (95%); while fatigue survival probability was analyzed with Kaplan-Meier and Mantel-Cox (log- rank, 95%).

Results: One-way ANOVA revealed that surface roughness was affected by the finishing protocol, where C + G showed the highest mean value (0.46 ± 0.18 µm)^A followed by G (0.30 ± 0.10 µm)^B, and C (0.19 ± 0.02 µm)^C. While for fatigue strength, the G protocol presented a higher mean value (243.00, and 222.36-263.63)^A, followed by C + G (192.75 and 186.61-198.88)^B and C (172.50 and 159.43-185.56)^C.

Conclusion: Surface finishing protocols modify the surface roughness and fatigue strength of high-translucent zirconia. Regardless of the surface roughness, both glazing protocols improved the ceramic fatigue strength, favoring the restoration's long-term survival.