Effect of surface treatments on shear bond strength between CAD/CAM glass fiber-reinforced composite block and veneering indirect composite material

This study aimed to evaluate the effect of different surface treatments and artificial aging on the shear bond strength between a CAD/CAM glass fiber-reinforced composite (FRC) block and a veneering indirect composite material. Four surface treatments-no surface treatment (NT), airborne-particle abrasion (AB), tribochemical silica coating (ROC), and hydrofluoric acid etching (HF)-were assessed with and without silane application. Specimens were subjected to thermocycling and mechanical loading to simulate aging. Shear bond strength was measured, and failure modes were analyzed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The AB group exhibited the highest bond strength without silane application. The ROC group combined with silane yielded the highest bond strength, particularly after thermal cycling. Mechanical loading reduced the effectiveness of silane application. These findings indicate that tribochemical silica coating followed by silanization provides a superior and durable bond between FRC blocks and veneering indirect composite materials.