Effect of Surface Treatments and Thermal Aging on Bond Strength Between Veneering Resin and CAD/CAM Provisional Materials

The oral environment significantly influences the aesthetic appearance of CAD/CAM provisional restorative materials. Therefore, a veneering layer is required. However, bonding veneering resin composites to these materials is challenging, especially when exposed to thermal aging. This study assessed the effect of different surface treatments and thermal aging on bond strength between veneering resin and CAD/CAM provisional materials. Provisional materials specimens including CAD-Temp, Everest C-Temp, and PEEK were randomly allocated to five groups. Group C: without any surface treatments. DB: mechanically roughened using a diamond bur; DB+TC: DB group with 5000 cycles of thermocycling; SB: aluminum oxide airborne abraded; SB+TC: SB group, along with 5000 cycles of thermocycling. Following the surface treatments, the specimens received primer and resin veneering composite. The bond strength (SBS) was evaluated. C-Temp in the SB group exhibited the highest SBS values (MPa), while CAD-Temp in the C group showed the lowest values. PEEK recorded significantly higher SBS in DB+TC and SB+TC groups than CAD-Temp in DB+TC and SB+TC. C-Temp exhibited higher SBS without surface treatment, whereas PEEK showed higher SBS after diamond bur roughening and air particle abrasion. Thermocycling significantly reduced bond strength in all materials except for PK material in the air particle abrasion group.