title: The effect of porcelain thickness and surface liner application on the fracture behavior of a ceramic system.
abstract: OBJECTIVE
  To determine the effect of porcelain thickness and the application of a surface liner (SL) on the flexural strength (σ) of a ceramic system.
  
  
  METHODS
  One hundred twenty bar-shaped specimens of yttria-stabilized zirconia-based ceramic were fabricated and randomly divided into two groups according to the application of SL: A - applied; B - not applied. The specimens were further divided according to the porcelain veneer thickness (n=20): 0-0.5mm; 1-1.0mm; 2-2.0mm. All specimens were tested in 3-point bending with the porcelain under tension. The maximum load was recorded at first sign of fracture, the σ was calculated and the mode of failure was determined. Data was statistically analyzed using one-way ANOVA, Tukey (α=0.05) and Weibull distribution.
  
  
  RESULTS
  The SL application had no effect (p=0.723) while the porcelain thickness had a significant effect (p=0.000) on the mean σ values. No significant differences in mean σ values were found with same porcelain thickness. A 0.5-mm thick porcelain layer (groups A0 and B0) showed greater mean σ values than other groups. The Weibull modulus (m) ranged from 6 (groups A1 and B2) to 9 (groups A0, A2 and B0). The predominant mode of failure for all groups was fracture initiation at the porcelain surface propagating to the ceramic interface.
  
  
  CONCLUSIONS
  The porcelain thickness influenced the mean σ values, but the SL had no significant effect on the flexural strength and the mode of failure of the ceramic system examined.
authors.affiliation: São Paulo State University, Department of Dental Materials and Prosthodontics, São José dos Campos, SP, Brazil.
authors.forename: Paula
authors.initials: P
authors.lastname: Benetti
authors.forename: Fernanda
authors.initials: F
authors.lastname: Pelogia
authors.forename: Luiz Felipe
authors.initials: LF
authors.lastname: Valandro
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino
authors.forename: Alvaro Della
authors.initials: AD
authors.lastname: Bona
mesh_terms: D000704:Analysis of Variance; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D008422:Materials Testing; D018583:Pliability; D013499:Surface Properties; D016019:Survival Analysis; D013718:Tensile Strength; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide