title: Effects of cobalt-chromium alloy surface casting on resistance to deflection fatigue and surface hardness of titanium.
abstract: This study investigated the resistance to deflection fatigue and surface hardness of grade 2 titanium bar samples to a portion of which a layer of cobalt-chromium alloy was cast under standard dental laboratory conditions. The uncovered part of the titanium bar was deflected, and the number of loading cycles required to cause a fatigue fracture in the titanium bar was recorded. The Vickers hardness of the titanium bar was measured, and the fracture surface was examined by scanning electron microscope and energy-dispersive spectroscopy. The number of loading cycles was considerably lower in bars with the cobalt-chromium surface cast (83 vs. 13.770 cycles) (P < .001), while the surface hardness of the titanium bar with the cobalt-chromium surface cast was higher than that without the surface cast (Vickers hardness number 329 vs. 178) (P < .001). These findings suggest that the cobalt-chromium surface cast dramatically affects the fatigue resistance of pure titanium, which should be considered when novel implant-supported prostheses made from premanufactured titanium parts are planned.
authors.affiliation: Nordisk Institutt for Odontologisk Material Prøvning, Scandinavian Institute of Dental Materials, Haslum, Norway.
authors.forename: P K
authors.initials: PK
authors.lastname: Vallittu
authors.forename: K
authors.initials: K
authors.lastname: Luotio
mesh_terms: D000704:Analysis of Variance; D002858:Chromium Alloys / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry; D003735:Dental Casting Technique; D003799:Dental Stress Analysis; D006244:Hardness; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D002858:Chromium Alloys; D003035:Cobalt; D014025:Titanium