title: The influence of interfacial surface roughness on bilayered ceramic specimen performance.
abstract: OBJECTIVE
  The aim of the current study was to assess the influence of interfacial surface roughness on the performance of bilayered ceramic composite disc-shaped specimens.
  
  
  METHODS
  Specific surface flaw distributions were introduced to a series of standard aluminous core porcelain disc specimens (12 mm diameter, 1.7 mm thickness) prior to bilayering with dentin porcelain. Mean flexure strengths, standard deviations and associated Weibull moduli (m) were determined using bi-axial flexure (ball-on-ring) for each series of 30 bilayered specimens.
  
  
  RESULTS
  The mean bi-axial fracture strengths of bilayered specimens resulted in significant differences between specimen groups with the smoothest interfacial roughness recording the highest strength and fracture strength reliability. Specimen delamination was identified in five of the bilayered group with the smoothest interfacial roughness compared with no specimen delaminations in the rougher interface groups. However, fracture occurred in the weaker dentin layer rather than along the interface between the dentin and core porcelain for specimens in these rougher interface groups.
  
  
  CONCLUSIONS
  A smoother interfacial surface roughness resulted in increased performance, namely increased strength and reliability amongst the bilayered dental ceramic composite specimens examined in the current investigation. The incidence of complete or partial delamination of the reinforcing core and aesthetic dentin was increased for these specimens since the reduced tortuosity of the interface between porcelain layers fails to restrict propagation of a crack front along the interface.
authors.affiliation: Biomaterials Unit, School of Dentistry, University of Birmingham, St Chad's Queensway, B4 6NN Birmingham, UK. g.j.flemming@bham.ac.uk
authors.forename: Garry J P
authors.initials: GJ
authors.lastname: Fleming
authors.forename: Sherin F A
authors.initials: SF
authors.lastname: El-Lakwah
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Harris
authors.forename: Peter M
authors.initials: PM
authors.lastname: Marquis
mesh_terms: D000535:Aluminum; D003775:Dental Polishing; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis; D003801:Dental Veneers; D008422:Materials Testing; D018583:Pliability; D013499:Surface Properties; D016019:Survival Analysis
chemical_list: C483027:vitadur alpha; D003776:Dental Porcelain; D000535:Aluminum