title: Failure responses of a dental porcelain having three surface treatments under three stressing conditions.
abstract: OBJECTIVE
  Surface conditions are of interest in all-ceramic restorations since they can control both bonding and strength. Tensile testing methods are commonly used to evaluate surface conditions of ceramics. This work evaluated tensile properties of a feldspathic ceramic as-finished, sandblasted and etched under three stressing conditions: (1) biaxial flexure; (2) monotonic mastication loading, dry; and, (3) cyclic mastication loading, wet.
  
  
  METHODS
  Feldspathic CAD/CAM blocks were sliced into Tabs 1mm thick, n=135 specimens were divided into 3 groups assigned to as-finished (600 grit SiC; control), sandblasted, and etched. Of the 45 specimens per group, 35 specimens were used for bonded tests and 10 specimens for biaxial flexure testing. Pin-on-three ball biaxial testing was performed per ISO 6872. 35 specimens were bonded to dentin-analog bases and loaded to radial crack pop-in beneath a 3mm diameter piston. 20 specimens were tested dry with failure determined by acoustic emission methods. 15 specimens, bonded to bases having micro-channels for water transport, were cyclically loaded beneath the 3mm piston under water at 15Hz for 500,000 cycles.
  
  
  RESULTS
  Biaxial flexure distinguished among all three surface conditions (p<0.05, ANOVA). Monotonic testing could not distinguish among groups. Cyclic testing could not distinguish between sandblasted and etched groups but both were weaker than as-finished.
  
  
  CONCLUSIONS
  Mastication loading of bonded specimens creates a different stress state than simple flexure due to contributions of the cement-ceramic interface. Water adds a damage accumulation effect. Tensile stress conditions need to be chosen with the desired outcomes considered.
authors.affiliation: Department of Prosthodontics, Section of Dentistry, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
authors.forename: Yang-Jin
authors.initials: YJ
authors.lastname: Yi
authors.forename: J Robert
authors.initials: JR
authors.lastname: Kelly
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000465:Algorithms; D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D001732:Bite Force; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D001840:Dental Bonding; D045662:Dental Etching / Q000379:methods; D003775:Dental Polishing / Q000379:methods; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D055119:Elastic Modulus; D004853:Epoxy Resins / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D006801:Humans; D006858:Hydrofluoric Acid / Q000737:chemistry; D008422:Materials Testing; D010710:Phosphates / Q000737:chemistry; D018583:Pliability; D017680:Potassium Compounds / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry; D013016:Sound; D013314:Stress, Mechanical; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D017554:Carbon Compounds, Inorganic; D004853:Epoxy Resins; C093719:Panavia TPN-S; D010710:Phosphates; D017680:Potassium Compounds; D019279:Resin Cements; D017655:Silicon Compounds; C009753:fiberglass; D014867:Water; D003776:Dental Porcelain; C016447:feldspar; D000537:Aluminum Oxide; D006858:Hydrofluoric Acid; C022088:silicon carbide