title: Fracture surface characterization of dentin-bonded interfacial fracture toughness specimens.
abstract: Although the current trend in dentin bonding favors the development of a hybrid layer interdiffusion zone for micromechanical bonding, the exact nature of the dentin-composite bond is still unclear. The objective of this study was to characterize the fracture surfaces of specimens used to measure interfacial fracture toughness. Morphological (SEM) and chemical (EDS and XPS) surface analyses were used for characterization. Fracture toughness specimens generally failed along the dentin-bonded interface in agreement with observed clinical failure modes. Four sites of bond failure were identified within the dentin-composite interfaces when All-Bond 2, Scotchbond Multi-Purpose, and Scotchbond 2 were used as the dentinal adhesives. These were located within (1) the smear layer, (2) a resin-modified layer between the interdiffusion zone and the adhesive resin, (3) a well-infiltrated hybrid interdiffusion zone, and (4) a non-infiltrated unsupported collagen layer. The interfacial region had a complex architecture which varied with the nature of the dentin, the dentin surface treatment, and the dentin bonding system. The sites of bond failure appeared to correlate with the interfacial fracture toughness and the extent to which polymerized resin infiltrated and acted to support the organic dentinal structures.
authors.affiliation: Department of Restorative Dentistry, Centre for Biomaterials, Faculty of Dentistry, Toronto, Ontario, Canada.
authors.forename: L E
authors.initials: LE
authors.lastname: Tam
authors.forename: R M
authors.initials: RM
authors.lastname: Pilliar
mesh_terms: D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry; D003804:Dentin / Q000737:chemistry / Q000648:ultrastructure; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements; D016369:Smear Layer; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: C074864:All-Bond system; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; C067788:scotchbond 2