title: Influence of Veneering Fabrication Techniques and Gas-Phase Fluorination on Bond Strength between Zirconia and Veneering Ceramics.
abstract: OBJECTIVE
  Porcelain chipping has been one of the main problems of porcelain-fused-to-zirconia restorations. This study evaluates the bond strengths of layered, pressed, and adhesively bonded porcelain to yttria-stabilized zirconia substrates that have undergone traditional preparation or gas-phase fluorination.
  
  
  METHODS
  A three-point bending test was used to evaluate the bond strength of the porcelain and zirconia interface. Sixty-six specimens were prepared (n = 11) following ISO 9693 and loaded until failure using an Instron testing machine. One-half of the zirconia substrates received gas phase fluorination treatment before veneering application. Three porcelain veneering methods were evaluated: layered, pressed, and adhesively bonded porcelain. Bond strength results were interpreted using a two-way ANOVA and a Bonferroni multiple comparisons test. Statistical significance was set at α = 0.05.
  
  
  RESULTS
  ANOVA revealed a statistically significant effect of the veneering fabrication methods. No main effect was observed regarding the surface treatment to the zirconia. There was a significant effect related to the veneering method used to apply porcelain to zirconia. For untreated zirconia, layered porcelain had a significantly higher flexural strength compared to pressed or bonded, while pressed and bonded porcelains were not significantly different from one another. For zirconia specimens receiving fluorination treatment, both layered and pressed porcelains had significantly higher bond strengths than adhesively bonded porcelain. In addition, fluorinated pressed porcelain was not statistically different from the control layered or fluorinated layered porcelain.
  
  
  CONCLUSIONS
  The choice of veneering fabrication technique was critical when evaluating the zirconia to porcelain interfacial bond strength. Bonded porcelain to zirconia had a lower flexural strength than layered or pressed porcelain, regardless of zirconia surface treatment. In addition, fluorination had an effect on the bond strength of pressed porcelain.
authors: Private Practice, Austin, TX.
authors: Stewart W
authors: SW
authors: Pharr
authors: Department of Operative Dentistry, University of Iowa, Iowa City, IA.
authors: Erica C
authors: EC
authors: Teixeira
authors: Department of Comprehensive Dentistry, University of Texas Health Science Center, San Antonio, TX.
authors: Ronald
authors: R
authors: Verrett
authors: RTI International, Center for Materials and Electronic Technologies, Durham, NC.
authors: Jeffrey R
authors: JR
authors: Piascik
mesh_terms: D002516:Ceramics; D003776:Dental Porcelain; D003799:Dental Stress Analysis; D003801:Dental Veneers; D054879:Halogenation; D006801:Humans; D008422:Materials Testing; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide
keywords: Ceramics; bond strength; gas-phase fluorination; zirconia