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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Can ceramic veneer spark erosion and mechanical cycling affect the accuracy of milled complete-arch frameworks supported by 6 implants?

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Silva, Leticia Del Rio [1] ; Veloso, Daniele Valente [1] ; Barbin, Thais [1] ; Borges, Guilherme Almeida [1] ; Camacho Presotto, Anna Gabriella [1] ; Mesquita, Marcelo Ferraz [1]
Total Authors: 6
[1] Univ Campinas UNICAMP, Piracicaba Dent Sch, Dept Prosthodont & Periodontol, Piracicaba - Brazil
Total Affiliations: 1
Document type: Journal article
Source: JOURNAL OF PROSTHETIC DENTISTRY; v. 126, n. 6, p. 772-778, DEC 2021.
Web of Science Citations: 0

Statement of problem. Milling is a well-established method for manufacturing prosthetic frameworks. However, information about the influence of ceramic veneer and spark erosion on the accuracy of the all-on-six complete-arch fixed frameworks manufactured from different materials is lacking. Purpose. The purpose of this in vitro study was to compare the accuracy of milled complete-arch fixed frameworks with zirconia, cobalt-chromium, and titanium at different steps of their manufacturing process and the influence of mechanical cycling. Material and methods. Fifteen milled complete-arch fixed frameworks, supported by 6 implants, were made in zirconia, cobalt-chromium, and titanium (n=5). The fit was measured by the single-screw test protocol. Stress was measured by photoelastic analysis. The loosening torque was evaluated by tightening the screws, retightening them after 10 minutes, and then evaluating the loosening torque 24 hours later. Thereafter, all frameworks received ceramic veneer, and the previous tests were repeated. Cobalt-chromium and titanium frameworks received spark erosion after ceramic veneer, and all analyses were repeated. Before and after mechanical cycling, loosening torque was evaluated. The results were subjected to 2-way repeated-measures ANOVA and the Bonferroni test (alpha=.05). Results. Titanium presented higher fit values than zirconia (P=.037) and similar to cobalt-chromium frameworks (P>.05) at baseline. After ceramic veneer, higher fit levels were observed for zirconia (P=.001) and cobalt-chromium (P=.008). Titanium showed higher stress values (P<.05) regardless of time. Baseline for all materials presented lower stress values (P<.05). Higher loosening torque values were found for the titanium group at baseline (P<.001) and after ceramic veneer (P<.001). Spark erosion improved fit and loosening torque values only for cobalt-chromium (P<.05). Mechanical cycling did not influence the loosening torque (P>.05). Conclusions. Titanium milled complete-arch fixed frameworks presented poorer fit values than zirconia, although the loosening torque at baseline was higher. Ceramic veneer increased the fit levels for zirconia and cobalt-chromium, decreased the loosening torque values for cobalt-chromium, and enhanced stress levels. Spark erosion can be a reliable technique to improve fit and loosening torque for cobalt-chromium frameworks. Mechanical cycling did not decrease loosening torque. (AU)

FAPESP's process: 17/16303-3 - Comparative study of manufacturing techniques of maxillary complete-arch prosthesis: planning, materials, marginal misfit, loosening torque, ceramic coverage, mechanical cycling and stress distribution
Grantee:Marcelo Ferraz Mesquita
Support type: Regular Research Grants