Purpose: To evaluate the effect of thermocycling on the water contact angle (WCA), surface roughness (SR), and microhardness (MH) of resin-matrix computer-assisted design and computer-assisted manufacturing (CAD-CAM) ceramics after different surface treatments (conventional polishing or 2 different surface sealants). Material and methods: Two different types of resin-matrix CAD-CAM ceramics; a nanoparticle-filled resin (CeraSmart; CS) and a resin nanoceramic (Lava Ultimate; LU) were tested. Rectangular-shaped plates (1 mmthick) were divided into 3 groups (n = 8) in terms of surface treatment methods applied: conventional polishing (control) or 2 surface sealants (Optiglaze (OG) and Palaseal (PS)). Scanning electron microscope images ( ? 1000 and ? 700 magnifications) of each material were taken from 2 additional specimens before surface treatments. After surface treatments, WCAs of deionized water, SR, and MH values of specimens were measured. All specimens were subjected to 5000 thermocycling and measurements were repeated. SR, WCA, and MH data before and after thermocycling were compared by using a 2-way ANOVA (?=.05). Results: A significant interaction was found between the surface treatment and the material for WCA after thermocycling (P < .001), for SR before thermocycling (P = .014), and for MH both before and after thermocycling (P .001). SEM images before surface treatments revealed that the surface of CS was mechanically rougher with a more microretentive topography compared with the surface of LU. No significant correlation was found between SR and WCA (P 0.05). Conclusions: Thermocycling affected the SR, MH, and WCA of all resin-matrix CAD-CAM ceramics.