Work

Effect of CAD/CAM milling protocols on surface topography and mechanical behavior of polycrystalline zirconia

Year: 2025

Type: article

Abstract: Objectives Even though improvements in CAD/CAM technology have allowed the milling protocol to be modified according to specific treatment requirements, it remains unclear how different protocols affect the surface quality and mechanical properties of the final restoration. This study aims to evaluate the effect of the CAD/CAM milling protocol on the topography, flexural strength, and reliability of 3 mol% yttria partially stabilized zirconia (3Y-PSZ). Methods Disc-shaped specimens (∅12 mm×1.2 mm) were fabricated using three different CAD/CAM dry-milling protocols (n = 20): slow (S), normal (N), and fast (F). Control polished specimens were fabricated by cutting pre-sintered CAD/CAM blocks using a cutting machine and polishing with silicon carbide papers, in wet (P wet ) and dry (P dry ) conditions (n = 20). Surface topography was evaluated using an optical profilometer (n = 3). Specimens were subjected to a piston-on-three-balls flexural strength test using a universal testing machine. Fractographic analysis was performed using optical and scanning electron microscopes. The characteristic flexural strength (σ 0 ), Weibull modulus ( m ), and the 90 % confidence intervals (90 % CI) were estimated. XRD was used to identify the tetragonal, cubic, and monoclinic phases. Results Distinct topographies were observed for polished and CAD/CAM-milled specimens. Surface roughness parameters (Sa and Sz) followed a decreasing order: F > N > S > P (P wet and P dry) There was no difference for σ 0 and m values among the three CAD/CAM milling protocols. P dry had similar σ 0 and m to CAD/CAM-milled groups, while P wet resulted in lower values. Significance Distinct CAM-milling protocols produce apparent differences in the topography of 3Y-PSZ while preserving flexural strength and reliability.

Source: Dental Materials

DOI: 10.1016/j.dental.2025.11.004

Authors: Laura Carolina Kepler, Paula Benetti, Vitor Trancoso Britto, Alvaro Della Bona, Yu Zhang, Marcia Borba

Institutions: Universidade de Passo Fundo, University of Pennsylvania, University of Manchester

Language: English

Topic: Dental materials and restorations

Subfield: Orthodontics

Field: Dentistry

Domain: Health Sciences

Open Access status: hybrid

Estimated APC paid: $4,560

Funders: Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, National Institutes of Health, National Institute of Dental and Craniofacial Research