The effect of adhesives with various degrees of hydrophilicity on resin ceramic bond durability

Objectives: To investigate the role of different acid surface-treatments and hydrophilic and hydrophobic bonding agents on resin ceramic bond durability. Methods: Two resin cements, Tetric Flow and Nexus 2, were applied to CAD/CAM Cerec Vitablocs with six bonding strategies: (1) HF-etching and silanization, (2) HF-etching, silanization and application of a hydrophilic bonding agent, (3) HF-etching, silanization and application of a hydrophobic bonding agent, (4) H3PO4-treatment and silanization, (5) H3PO4-treatment, silanization and application of a hydrophilic bonding agent, and (6) H3PO4-treatment, silanization and application of a hydrophobic bonding agent. The hydrophilic agents were Syntac Single-Component and OptiBond Solo Plus. The hydrophobic agent was Visio Bond. After 1 d water storage at 37 °C, 1 mm2 microbars were cut for the microtensile bond strength test (μTBS test). The microbars were subjected to a tensile load using a modified testing device immediately after trimming and after 7 and 28 d water storage. The fractured specimens were examined with a stereomicroscope and scanning eslectron microscopy to determine the failure mode. Results: HF-etching resulted in significantly higher μTBS than H3PO4-treatments (p<0.001). The 1 d μTBS with hydrophilic bonding agents was significantly higher than with the hydrophobic bonding agent (p<0.001), but decreased with time after water storage (p<0.001), while bonds with the hydrophobic bonding agent remained stable. The percentages of adhesive failures after 1, 7, and 28 d were 60, 86, and 94, respectively. Significance: Bonding agents that contain hydrophilic monomers have a negative influence on the resin ceramic bond durability.