Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Dentistry, Oral Surgery & Medicine, adhesion, composite resin, computer-aided design, computer-aided manufacturing (CAD, CAM), dental cement, dual cure, interfacial fracture toughness, light cure, resin-based luting composite, INTERFACIAL FRACTURE-TOUGHNESS, GLASS-CERAMIC INLAYS, BOND STRENGTH, MECHANICAL-PROPERTIES, CLINICAL-PERFORMANCE, RESIN, POLYMERIZATION, CONVERSION, IMMEDIATE, MICROHARDNESS, computer-aided design/computer-aided manufacturing (CAD/CAM), resin-based luting composite., Composite Resins, Curing Lights, Dental, Dental Bonding, Dental Cements, Dental Stress Analysis, Light-Curing of Dental Adhesives, Materials Testing, Resin Cements, Surface Properties, 1105 Dentistry, Dentistry, 3203 Dentistry

Abstract:

PURPOSE: To validate the rationale of using a conventional light-curing resin-based composite (RBC) to lute thick indirect restorations by measuring mini-interfacial fracture toughness (mini-iFT). MATERIALS AND METHODS: Freshly exposed dentin of extracted third molars (n = 64) was immediately sealed with a thin layer of an experimental RBC with a 50 wt% or 75 wt% (IDS) filler load. Two- or 6-mm-thick CAD/CAM composite blocks were luted onto IDS using either pre-heated light-cure or dual-cure luting RBC, with the latter having served as control. Samples were cut into sticks, upon which a notch was prepared at the interface between IDS and luting RBC, prior to being submitted to a 4-point bending test to determine mini-iFT. The results were analyzed using a mixed linear model (LME). Failure mode at the fractured interface was determined using scanning electron microscopy (SEM). RESULTS: LME revealed that mini-iFT was not significantly affected by the composite block thickness (p = 0.39), but by the luting RBC (p < 0.0001) and the IDS RBC filler load (p = 0.0011). Mini-iFT was higher with 50 wt% filler-loaded RBC IDS and when luted using the light-curing RBC. CONCLUSION: This work provides the proof of concept that 2- and 6-mm-thick indirect restorations can safely be adhesively luted with pre-heated conventional light-cure RBC under controlled light-irradiation conditions. This strategy even seems beneficial in terms of mini-iFT compared to using a dual-cure luting RBC. IDS with lower filler content also appeared more favorable.