title: Review of the fracture toughness approach.
abstract: Dental adhesives are usually tested in shear or tension even though neither of these approaches measures the local stress triggering failure. Because the stress level varies extensively over the bonded surface, it seems as a fracture mechanics approach would be more appropriate. In this review different general aspects of fracture mechanics and adhesive joints were reviewed first. That review served as a foundation for a review of fracture toughness studies performed on dental adhesives. The dental adhesive studies were identified through a MEDLINE search using "dental adhesion testing AND enamel OR dentin AND fracture toughness" as search strategy. The outcome of the review revealed that fracture toughness studies performed on dental adhesives are complex, both regarding technical performance as well as achieving good discriminating ability between different adhesives. The review also suggested that most fracture toughness tests of adhesives performed in dentistry are not totally reliable because they usually did not consider the complex stress pattern at the adhesive interface. However, despite these limitations, the review strongly supports the notion that the proper way of studying dental adhesion is by use a fracture mechanics. At the present time, it seems as the fracture energy of adhesives might be more appropriate to determine than their fracture toughness values.
authors.affiliation: College of Dentistry, Department of Operative Dentistry, University of Florida, Box-J-100405 JHMHC, Gainesville, FL 32610-0405, USA. ksoderholm@dental.ufl.edu
authors.forename: Karl-Johan
authors.initials: KJ
authors.lastname: Soderholm
mesh_terms: D003188:Composite Resins; D001840:Dental Bonding; D003743:Dental Enamel; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000379:methods*; D003804:Dentin; D017220:Dentin-Bonding Agents; D055119:Elastic Modulus; D004735:Energy Transfer; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D007700:Kinetics; D008422:Materials Testing / Q000379:methods; D019279:Resin Cements; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; D019279:Resin Cements