title: Strain gauge analysis of the effect of porcelain firing simulation on the prosthetic misfit of implant-supported frameworks.
abstract: OBJECTIVE
  This study investigated the effect of porcelain firing on the misfit of implant-supported frameworks and analyzed the influence of preheat treatment on the dimensional alterations.
  
  
  METHODS
  Four external-hex cylindrical implants were placed in polyurethane block. Ten frameworks of screw-retained implant-supported prostheses were cast in Pd-Ag using 2 procedures: (1) control group (CG, n = 5): cast in segments and laser welded; and test group (TG, n = 5): cast in segments, preheated, and laser welded. All samples were subjected to firing to simulate porcelain veneering firing. Strain gauges were bonded around the implants, and microstrain values (με = 10⁻⁶ε) were recorded after welding (M1), oxidation cycle (M2), and glaze firing (M3). Data were statistically analyzed (2-way analysis of variance, Bonferroni, α = 0.05).
  
  
  RESULTS
  The microstrain value in the CG at M3 (475.2 με) was significantly different from the values observed at M1 (355.6 με) and M2 (413.9 με). The values at M2 and M3 in the CG were not statistically different. Microstrain values recorded at different moments (M1: 361.6 με/M2: 335.3 με/M3: 307.2 με) did not show significant difference.
  
  
  CONCLUSIONS
  The framework misfit deteriorates during firing cycles of porcelain veneering. Metal distortion after porcelain veneering could be controlled by preheat treatment.
authors.affiliation: Department of Dentistry, Health Sciences Center, Federal University of Santa Catarina, Campus Universitário Reitor João David Ferreira Lima, Santa Catarina, Brazil.
authors.forename: Diego Klee
authors.initials: DK
authors.lastname: De Vasconcellos
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
authors.forename: Cláudia Ângela
authors.initials: CÂ
authors.lastname: Maziero Volpato
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino
authors.forename: Esra Salihoğlu
authors.initials: ES
authors.lastname: Yener
mesh_terms: D000704:Analysis of Variance; D003735:Dental Casting Technique; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D016876:Metal Ceramic Alloys; D014896:Welding
chemical_list: D016876:Metal Ceramic Alloys; D003776:Dental Porcelain