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

To investigate the role of different acid surface-treatments and hydrophilic and hydrophobic bonding agents on resin ceramic bond durability.

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 1d water storage at 37 degrees C, 1 mm2 microbars were cut for the microtensile bond strength test (microTBS test). The microbars were subjected to a tensile load using a modified testing device immediately after trimming and after 7 and 28d water storage. The fractured specimens were examined with a stereomicroscope and scanning eslectron microscopy to determine the failure mode.

HF-etching resulted in significantly higher microTBS than H3PO4-treatments (p < 0.001) The 1d microTBS 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 28d were 60, 86, and 94, respectively.

Bonding agents that contain hydrophilic monomers have a negative influence on the resin ceramic bond durability.