title: Bond strength and Raman analysis of the zirconia-feldspathic porcelain interface.
abstract: BACKGROUND
  Zirconia has the best mechanical properties of the available ceramic systems. However, the stability of the zirconia-feldspathic porcelain interface may be jeopardized by the presence of the chipping and debonding of the feldspathic porcelain.
  
  
  OBJECTIVE
  The purpose of this study is to evaluate the shear bond strength of 3 cold isostatic pressed zirconia materials and a feldspathic veneer by analyzing their interface with micro-Raman spectroscopy.
  
  
  METHODS
  The test groups were experimental zirconia, Zirkonzahn zirconia, and Schuetz zirconia. Blocks of partially sintered zirconia were cut into disks (n=20) and then veneered with a feldspathic porcelain. Half of the specimens from each group (n=10) were incubated in 37°C water for 24 hours, and the other half were thermocycled. All the specimens were then subjected to shear testing. The fractured areas were analyzed with optical stereomicroscopy and classified as adhesive, cohesive, or an adhesive-cohesive failure. Spectral patterns were examined to detect bands related to the zirconia and feldspathic porcelain phases. The shear strength data were submitted to 2-way ANOVA.
  
  
  RESULTS
  No significant differences in shear bond strength were observed among the 3 groups, regardless of whether or not the specimens were thermocycled. Adhesive failures were the most prevalent types of failure (70%). Raman spectra were clearly distinguished for all the materials, which showed the presence of tetragonal and monoclinic phases.
  
  
  CONCLUSIONS
  The controlled production of the experimental zirconia did not influence the results of the bond strength. Raman analysis suggested a process of interdiffusion by the presence of peaks associated with the zirconia and feldspathic ceramics.
authors.affiliation: Doctoral student, Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Carla Müller
authors.initials: CM
authors.lastname: Ramos
authors.affiliation: Professor, Department of Biomaterials and Oral Biology, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Paulo Francisco
authors.initials: PF
authors.lastname: Cesar
authors.affiliation: Professor, Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Rafael Francisco
authors.initials: RF
authors.lastname: Lia Mondelli
authors.affiliation: Professor, Department of Physics, Faculty of Science, São Paulo State University, Bauru, SP, Brazil.
authors.forename: Americo Sheitiro
authors.initials: AS
authors.lastname: Tabata
authors.affiliation: Graduate student, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Juliete
authors.initials: J
authors.lastname: de Souza Santos
authors.affiliation: Professor, Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil. Electronic address: afborges@fob.usp.br.
authors.forename: Ana Flávia
authors.initials: AF
authors.lastname: Sanches Borges
mesh_terms: D000268:Adhesiveness; D000538:Aluminum Silicates / Q000737:chemistry*; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003801:Dental Veneers; D006801:Humans; D008422:Materials Testing; D018613:Microscopy, Confocal; D015591:Microspectrophotometry / Q000379:methods; D017680:Potassium Compounds / Q000737:chemistry*; D033081:Shear Strength; D013059:Spectrum Analysis, Raman / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D003764:Dental Materials; D017680:Potassium Compounds; C499362:yttria stabilized tetragonal zirconia; D014867:Water; D003776:Dental Porcelain; C016447:feldspar; D015019:Yttrium; D015040:Zirconium; C028541:zirconium oxide