title: An in vitro study of the effect of different restorative materials on the reliability of a veneering porcelain.
abstract: BACKGROUND
  Implant-supported, porcelain veneered restorations experience a greater rate of porcelain fracture than tooth-supported restorations. For completely edentulous patients, one approach to minimizing porcelain fracture is to use acrylic resin in the mandible, although its efficacy is unknown.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the reliability of a veneering porcelain fatigued with different restorative materials in vitro.
  
  
  METHODS
  Fifty-nine veneering porcelain disk specimens were fabricated by layering veneering porcelain on nickel-chromium base metal alloy disks. Four groups of different indenter materials fatigued the porcelain specimens: group WC, tungsten carbide served as a control; group FC, pressed leucite glass ceramic; group NHC, nanohybrid composite resin denture tooth; and group AR, unfilled acrylic resin denture tooth. Porcelain specimens were randomly divided into 4 groups (n=14). A step-stress accelerated life-testing model was used. Use-level probability Weibull plots were generated, and the reliability of each group was estimated for a theoretical completion of 50 000 cycles at 150 N.
  
  
  RESULTS
  Nanohybrid composite resin and unfilled acrylic resin denture tooth groups had higher reliability than tungsten carbide and leucite glass ceramic groups. No significant differences existed between the reliability of the tungsten carbide and leucite glass ceramic groups and the nanohybrid composite resin and acrylic resin denture tooth groups.
  
  
  CONCLUSIONS
  Veneering porcelain disk specimens fatigued with the unfilled acrylic resin and nanohybrid composite resin denture tooth indenters exhibited higher reliability than the specimens fatigued with either the tungsten carbide or leucite glass ceramic indenters. All of the veneering porcelain disk specimens failed with the same mode of fracture, although the surface posttest exhibited different fracture characteristics among specimens fatigued with the 4 different materials.
authors.affiliation: Graduate student, Graduate Prosthodontics, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Anderson
authors.forename: Kwok-Hung
authors.initials: KH
authors.lastname: Chung
authors.forename: Brian D
authors.initials: BD
authors.lastname: Flinn
authors.forename: Ariel J
authors.initials: AJ
authors.lastname: Raigrodski
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D002858:Chromium Alloys / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003801:Dental Veneers; D055119:Elastic Modulus; D006801:Humans; D008422:Materials Testing; D053761:Nanocomposites / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D017973:Tungsten Compounds / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D000538:Aluminum Silicates; D002858:Chromium Alloys; D003188:Composite Resins; D003764:Dental Materials; D017973:Tungsten Compounds; C002802:tungsten carbide; D003776:Dental Porcelain; C078519:leucite; C023506:Glass ceramics