title: Improving fatigue damage resistance of alumina through surface grading.
abstract: Porcelain-veneered alumina crown restorations often fail from bulk fracture resulting from radial cracks that initiate at the cementation surface with repeated flexure of the stiffer crown layers on the soft dentin support. We hypothesized that bulk fracture may be substantially mitigated by grading the elastic modulus at the crown surfaces. In this study, we fabricated graded structures by infiltrating glass into dense alumina plates, resulting in a diminished modulus at the surface layers. The plates were then bonded to polycarbonate substrates and subjected to fatigue loading in water. Tests were terminated when fracture occurred at the cementation tensile surface or at the fatigue endurance limit (1 million cycles). Infiltrated specimens showed a significant increase in fatigue fracture loads over non-infiltrated controls. Our results indicate that controlled elastic gradients at the surface could be highly beneficial in the design of fracture-resistant alumina crowns.
authors.affiliation: Department of Chemical, Materials & Biomolecular Engineering, Center for Clean Energy Engineering, University of Connecticut, 191 Auditorium Road, Unit 3222, Storrs, CT 06269-3222, USA.
authors.forename: L
authors.initials: L
authors.lastname: Ren
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Bhowmick
authors.forename: Y B
authors.initials: YB
authors.lastname: Gerbig
authors.forename: M N
authors.initials: MN
authors.lastname: Janal
authors.forename: V P
authors.initials: VP
authors.lastname: Thompson
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D019544:Equipment Failure Analysis; D005898:Glass; D016014:Linear Models; D008422:Materials Testing; D018583:Pliability; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D003776:Dental Porcelain; D000537:Aluminum Oxide