Shear Bond Strength of Different CAD/CAM Ceramics: Acid vs Er:YAG Laser Etching

To evaluate whether Er:YAG laser etching could be an alternative surface treatment to hydrofluoric (HF) acid etching.

Surface treatment is important to bonding properties and utility times of computer aided design/computer aided manufacture (CAD/CAM) dental ceramics. The traditional method of HF acid etching is harmful to humans if not handled properly.

Four different CAD/CAM ceramics (Vita Mark II, IPS Empress CAD, IPS e.max CAD, and Vita Enamic) were cut into 72 blocks and divided into 6 groups according to different surface treatments (n = 12): Group A: no treatment; Group B: HF acid; and Group C to F: different Er:YAG laser power settings (300, 400, 500, and 600 mJ). Ten blocks of each group were measured for shear bond strength (SBS) and the failure modes were evaluated; the rest blocks were observed by scanning electronic microscopy (SEM).

HF acid etching resulted in the highest SBS for Vita Mark II, IPS Empress CAD, and Vita Enamic; however, the difference was not statistically significant (p > 0.05) compared to the second highest group of laser with 600 mJ in IPS Empress CAD. For IPS e.max CAD, the highest SBS was obtained from laser group with 400 mJ. The SBS results were consistent with failure modes and surface characterizations in SEM images.

Our results showed that Er:YAG laser had little impact on Vita Mark II and Vita Enamic; but proper power settings could be an alternative surface treatment to HF acid etching (600 mJ for IPS Empress CAD and 400 mJ for IPS e.max CAD).