Ceramic strengthening by tuning the elastic moduli of resin-based luting agents

ObjectiveResin-based luting agents (RBLAs) with tuned elastic moduli (E) were prepared and their influence on the strengthening, reliability, and mode of failure of luted feldspar ceramic was investigated.MethodsRBLAs with low E (2.6 GPa), intermediate E (6.6 GPa), and high E (13.3 GPa) were prepared and used to coat acid-etched ceramic disks. Positive (untreated ceramic) and negative (acid-etched ceramic) control groups were tested. The response variables (n = 30) were biaxial flexural strength (σbf, MPa), characteristic strength (σ0, MPa), and Weibull modulus at the ceramic surface (z = 0) and luting agent surface (z = −t2). A 3D finite element analysis simulated the biaxial flexural test. Fractographic analysis and morphology of the bonded interfaces were analyzed using scanning electron microscopy.ResultsThe RBLAs improved σbf and σ0 at z = 0, particularly those with intermediate and high E, whereas the mechanical reliability was only affected in the negative control. At z = −t2, differences between all RBLAs were observed but the structural reliability was independent of the RBLA tested. Increasing E of the RBLA was associated with increased stress concentration at the RBLA and reduced stresses reaching the ceramic. Failures originated on the ceramic surface at the ceramic-cement interface. In the high E group, failure sometimes originated from the RBLA free surface. All RBLAs completely filled the ceramic irregularities.SignificanceIncreased E of the RBLA reduced the variability of strength, the stress reaching the ceramic structure, and sometimes altered the origin of failure. The use of high E RBLAs seems beneficial for luting feldspar ceramics.