title: A photoelastic assessment of residual stresses in zirconia-veneer crowns.
abstract: Residual stresses within the veneer are linked to the high prevalence of veneer chipping observed in clinical trials of zirconia prostheses. We hypothesized that the thermal mismatch between the zirconia infrastructure and the veneer porcelain, as well as the rate used for cooling zirconia-veneer crowns, would be directly proportional to the magnitude of residual stresses built within the veneer layer. Two porcelains with different coefficients of thermal expansion were used to veneer zirconia copings, to create high or low thermal mismatches. The crowns were cooled according to a fast- or a slow-cooling protocol. The retardation of polarized light waves was used to calculate the residual stress magnitude and distribution across the veneer, according to the photoelasticity principle, in 1.0-mm-thick crown sections. While thermal mismatch was an important factor influencing the maximum stress development in the veneer, cooling rate had a minor role. Curved surfaces were preferential sites for stress concentration regardless of thermal mismatch or cooling rate.
authors.affiliation: Universidade Federal de Santa Catarina, Florianópolis, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Belli
authors.forename: S
authors.initials: S
authors.lastname: Monteiro
authors.forename: L N
authors.initials: LN
authors.lastname: Baratieri
authors.forename: H
authors.initials: H
authors.lastname: Katte
authors.forename: A
authors.initials: A
authors.lastname: Petschelt
authors.forename: U
authors.initials: U
authors.lastname: Lohbauer
mesh_terms: D001641:Bicuspid; D001718:Birefringence; D003080:Cold Temperature; D019245:Compressive Strength; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D004548:Elasticity; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D023861:Photography, Dental; D013718:Tensile Strength; D015040:Zirconium / Q000737:chemistry
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide