Interfacial fracture toughness of aged adhesive-dentin interfaces

Objective. To assess interfacial fracture toughness of different adhesive approaches and compare to a standard micro-tensile bond-strength (mu TBS) test after 6 months water storage. Methods. Chevron-notched beam fracture toughness (CNB) was determined using a modified ISO 24370:2005 standard. Adhesive-dentin micro-specimens (1.0 mm x 1.0 mm x 8-10 mm) were stressed in tensile until failure to determine the micro-tensile bond strength (mu TBS). Results. The highest mean mu TBS and interfacial fracture toughness were measured for the multi-step adhesives Clearfil SE Bond (Kuraray Noritake) and OptiBond FL (Kerr). While large differences were observed in the bond strength values (from 7.4 to 27.2 MPa) of the onestep self-etch adhesives tested, interfacial fracture toughness was less different (from 0.7 to 1.0 MPa m(1/2)). The adhesive with the lowest mean toughness (All-bond Universal, Bisco) had however the highest Weibull reliability, which might be a better parameter in regard to more consistent clinical performance. The self-adhesive composite Vertise Flow (Kerr) scored significantly lower at all levels. Signcance. Although the ranking of the adhesives tested using CNB and mu TBS corresponded well, the outcome of CNB appeared more reliable and less variable. (C) 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.