title: Influence of interlayer design on residual thermal stresses in trilayered and graded all-ceramic restorations.
abstract: Residual thermal stresses are formed in dental restorations during cooling from high temperature processing. The aim of this study was to evaluate the influence of constructive design variables (composition and interlayer thickness) on residual stresses in alumina- and zirconia-graded restorations. Restorations' real-like cooling conditions were simulated using finite elements method and temperature-dependent material properties were used. Three different designs were evaluated: a bilayered restoration (sharp transition between materials); a trilayered restoration with a homogenous interlayer between core and veneer; and a trilayered restoration with a graded interlayer. The interlayer thickness and composition were varied. Zirconia restorations presented overall higher thermal stress values than alumina ones. Thermal stresses were significantly reduced by the presence of a homogeneous interlayer. The composition of the interlayer showed great influence on the thermal stresses, with the best results for homogeneous interlayers being observed for porcelain contents in the composite ranging between 30%-50% (vol.%), for both alumina and zirconia restorations. The interlayer's thickness showed a minor contribution in the thermal stress reduction. The graded interlayer showed an optimized reduction in restorations' thermal stresses. The use of graded interlayer, favoring enhanced thermal stress distributions and lower magnitude is expected to reduce the risk of catastrophic failure.
authors.affiliation: Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina (UFSC), Campus Trindade, Florianópolis/SC, Brazil; CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal. Electronic address: brunohenriques@dem.uminho.pt.
authors.forename: Bruno
authors.initials: B
authors.lastname: Henriques
authors.affiliation: Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina (UFSC), Campus Trindade, Florianópolis/SC, Brazil.
authors.forename: Douglas
authors.initials: D
authors.lastname: Fabris
authors.affiliation: Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina (UFSC), Campus Trindade, Florianópolis/SC, Brazil; School of Dentistry (DODT), Post-Graduation Program in Dentistry (PPGO), Federal University of Santa Catarina, Campus Trindade, 88040-900, Florianópolis/SC, Brazil.
authors.forename: Júlio C M
authors.initials: JCM
authors.lastname: Souza
authors.affiliation: CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
authors.forename: Filipe S
authors.initials: FS
authors.lastname: Silva
authors.affiliation: Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina (UFSC), Campus Trindade, Florianópolis/SC, Brazil.
authors.forename: Joana
authors.initials: J
authors.lastname: Mesquita-Guimarães
authors.affiliation: Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York University, New York, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina (UFSC), Campus Trindade, Florianópolis/SC, Brazil.
authors.forename: Márcio
authors.initials: M
authors.lastname: Fredel
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D006358:Hot Temperature; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide
keywords: Alumina; Feldspar-based porcelain; Graded ceramics; Thermal residual stresses; Zirconia