Femtosecond laser versus hydrofluoric acid: Effects on the resin bond strength of CAD/CAM materials

This study evaluated the influence of femtosecond (fs) laser micromachining and hydrofluoric acid (HF)‐etching on the surface roughness (Ra) and resin bond strength of restorative materials. The study used 120 rectangular‐shaped specimens from four computer‐aided design/manufacturing (CAD/CAM) blocks (lithium‐disilicate glass‐ceramic [LDS; e.max CAD], leucite‐reinforced glass‐ceramic [LGC; Empress CAD], zirconia‐reinforced lithium‐silicate [ZLS; Vita Suprinity], and polymer‐infiltrated‐ceramic‐network [PICN; Vita Enamic]) and divided them into three subgroups based on the surface treatments applied: Control, HF‐etching (HF), and fs‐laser irradiation (FS). Surface roughness was measured using a surface profilometer. The surfaces were examined by a scanning electron microscope. A silane bonding agent was applied, and a self‐adhesive dual‐cure resin cement was bonded to the surfaces. The shear bond strength (SBS) test was conducted using a universal test device. FS‐treated groups had higher Ra than HF‐treated specimens. PICN showed higher Ra than other materials among the FS‐treated groups. The HF‐treated LDS showed the highest SBS. ZLS had the lowest SBS among the etched groups. Regardless of the material, the fs‐laser treatment resulted in significantly higher SBS values than seen for controls. Fs‐laser micromachining could be a promising alternative to conventional HF‐etching, given its potential to uniformly roughen the bonding surface of CAD/CAM materials and improve resin bonding.