Durability of four composite resin cements bonded to dentin under simulated pulpal pressure

Objectives. This study aimed to investigate the durability of four adhesive luting systems bonded to dentin with and without simulated hydrostatic pulpal pressure (PP). Methods. Composite blocks were bonded to dentin with four adhesive systems: Multilink Automix (MA), Multilink Sprint (MS), Clearfil Esthetic cement (CE) and RelyX ARC (RAC) under either a PP of 0 or 15cm H2O. After 3d water storage at 37 degrees C or thermal cycling (TC), of 30d with 5000 TC or 90d with 15,000 TC micro-tensile bond strength (mu TBS) was tested. Failure analysis of the bonding interface was performed using a scanning electron microscope (SEM). Results. Independent of PP application groups MA and RAC showed significantly higher mu TBS than CE and MS (P=0.05). A significant decrease in mu TBS was found for RAC and MS when subjected to PP (P=0.05), whereas CE and MA showed no significant difference (P>0.05). TC had no significant influence on the mu TBS in RAC, MA and CE without PP application (P>0.05), whereas CE with PP and MS showed a significant decrease in mu TBS (P=0.05) when subjected to TC. Significance. Based on these results, there were significant differences between materials. Pulpal pressure and artificial aging also seem to have an effect on in-vitro evaluation of bonding durability. If considered relevant to the materials service performance then these conditions should be applied in the materials testing.