Microtensile Bond Strength Between Resin-Matrix CAD/CAM Ceramics and Resin Cement after Various Surface Modifications and Artificial Aging

To evaluate the effect of different surface modification methods on the microtensile bond strength (μTBS) of four resin-matrix CAD/CAM ceramics after artificial aging.Specimens of four CAD/CAM materials (Shofu Block HC, Lava Ultimate, Brilliant Crios, and Vita Enamic) were prepared and divided into four groups. Each group received one of the following treatments: group 1 (INT): no surface modification; group 2: sandblasting with 29-μm Al2O3 particles (SB); group 3: hydrofluoric acid etching (9%) + silane (HF+Si); group 4: sandblasting with 30-μm particles of the CoJet system (CJ). The specimens of each group were luted together in pairs using resin cement (RelyX Ultimate). After one week of water storage (37°C), the sandwich specimens were sectioned into rectangular microspecimens and half of them were immediately subjected to μTBS testing, while the other half was tested after six months. Data were statistically analyzed using FFANOVA including the factors of material, treatment, and storage time, with α = 0.05.After one week, the lowest μTBS was observed for INT, while the highest was found for either mechanical (SB and CJ) or chemical (HF+Si) treatments (p0.05). After six months, a significant decrease in μTBS was observed depending on treatment (p0.05), while artificial aging significantly influenced the μTBS of all experimental groups (p0.05). During the two storage periods, the failure type was mainly interfacial and was associated with the type of surface modification.After artificial aging, the μTBS appeared to depend on srface modification, while the parameter "material" did not influence the results. Consequently, adhesive strategies should be oriented towards surface modification techniques.