title: Thermal/mechanical simulation and laboratory fatigue testing of an alternative yttria tetragonal zirconia polycrystal core-veneer all-ceramic layered crown design.
abstract: This study evaluated the stress levels at the core layer and the veneer layer of zirconia crowns (comprising an alternative core design vs. a standard core design) under mechanical/thermal simulation, and subjected simulated models to laboratory mouth-motion fatigue. The dimensions of a mandibular first molar were imported into computer-aided design (CAD) software and a tooth preparation was modeled. A crown was designed using the space between the original tooth and the prepared tooth. The alternative core presented an additional lingual shoulder that lowered the veneer bulk of the cusps. Finite element analyses evaluated the residual maximum principal stresses fields at the core and veneer of both designs under loading and when cooled from 900 degrees C to 25 degrees C. Crowns were fabricated and mouth-motion fatigued, generating master Weibull curves and reliability data. Thermal modeling showed low residual stress fields throughout the bulk of the cusps for both groups. Mechanical simulation depicted a shift in stress levels to the core of the alternative design compared with the standard design. Significantly higher reliability was found for the alternative core. Regardless of the alternative configuration, thermal and mechanical computer simulations showed stress in the alternative core design comparable and higher to that of the standard configuration, respectively. Such a mechanical scenario probably led to the higher reliability of the alternative design under fatigue.
authors.affiliation: Department of Prosthodontics, Integrated Center for Research - Bauru School of Dentistry, University of Sao Paulo, Bauru, São Paulo, Brazil. estevamab@gmail.com
authors.forename: Estevam A
authors.initials: EA
authors.lastname: Bonfante
authors.forename: Brian
authors.initials: B
authors.lastname: Rafferty
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Zavanelli
authors.forename: Nelson R F A
authors.initials: NR
authors.lastname: Silva
authors.forename: Elizabeth D
authors.initials: ED
authors.lastname: Rekow
authors.forename: Van P
authors.initials: VP
authors.lastname: Thompson
authors.forename: Paulo G
authors.initials: PG
authors.lastname: Coelho
mesh_terms: D001732:Bite Force; D003198:Computer Simulation; D017076:Computer-Aided Design; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000295:instrumentation; D003801:Dental Veneers; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D008963:Molar / Q000033:anatomy & histology; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013816:Thermodynamics; D013871:Thiones / Q000737:chemistry; D019231:Tooth Preparation, Prosthodontic; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium
chemical_list: C521707:Alloy Primer; D008689:Methacrylates; C483701:Rely X Unicem; D019279:Resin Cements; D013871:Thiones; C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium