title: Fatigue resistance of dentin/composite interfaces with an additional intermediate elastic layer.
abstract: According to the "elastic bonding" concept, a thick intermediate layer of flexible resin has been suggested to absorb part of the polymerization shrinkage stress and to absorb shocks during function. In this study, the effect of an additional intermediate layer of a low-viscosity resin on the microrotary fatigue resistance (microRFR) of a hybrid composite bonded to dentin was evaluated. The hypotheses tested were that an intermediate layer of a low-viscosity resin (i) increases the microRFR to dentin, but (ii) has no effect on the static bond strength. Microtensile bond strength (microTBS) samples were loaded until failure or inserted in a microrotary fatigue testing device. Specimens were tested at 4 Hz until failure or until 10(5) cycles were reached. An additional intermediate elastic layer had no effect on the static microTBS, but significantly lowered the median microRFR from 28.4 MPa to 21.6 MPa. However, the application of an intermediate flexible layer had, no effect on the static microTBS. In conclusion, an additional elastic intermediate layer did decrease significantly the microRFR (rejection of hypothesis i), but did not alter the microTBS (acceptance of hypothesis ii). The decrease in microRFR most likely may be explained by the lower mechanical properties of the intermediary layer.
authors.affiliation: Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, B-3000 Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: De Munck
authors.forename: Kirsten L
authors.initials: KL
authors.lastname: Van Landuyt
authors.forename: Eduardo
authors.initials: E
authors.lastname: Coutinho
authors.forename: André
authors.initials: A
authors.lastname: Poitevin
authors.forename: Marleen
authors.initials: M
authors.lastname: Peumans
authors.forename: Paul
authors.initials: P
authors.lastname: Lambrechts
authors.forename: Marc
authors.initials: M
authors.lastname: Braem
authors.forename: Bart
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004548:Elasticity; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D018583:Pliability; D019279:Resin Cements / Q000737:chemistry; D012399:Rotation; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014783:Viscosity
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C409388:Protect Liner F; D019279:Resin Cements; C092420:Clearfil Photo Posterior