OBJECTIVE To evaluate the effect of ceramic surface treatments on tensile bond strength (sigma) and the mode of failure of a resin bonded to a feldspathic glass and a low-crystalline ceramic, testing the hypothesis that a silica coating treatment is unnecessary for both the glass and the low-crystalline ceramic. METHODS 10 blocks of each the feldspathic glass (V7-VITAVM7) and the leucite-based ceramic (E1-IPS Empress) were fabricated and polished. Five blocks of each ceramic were treated as follows: 9.5% hydrofluoric acid for 60 seconds; and silica coating using Cojet System for 15 seconds. After silane coating, an adhesive resin and a composite were applied and polymerized. The composite-ceramic blocks were cut to produce bar-shaped specimens (n = 30) that were stored in distilled water at 37 degrees C for 7 days before tensile loading to failure in a universal testing machine. Data were statistically analyzed using analysis of variance, Tukey's test (alpha = .01) and Weibull analysis. Fracture surfaces were examined to determine the mode of failure. RESULTS The Weibull modulus (m) and mean sigma value (MPa) of Group E1HF (29.8 +/- 4.5) were significantly higher than other Groups (P = .0001). There was no statistical difference between Groups E1CS (24.6 +/- 5.6) and V7HF (22.3 +/- 4.0). Group V7CS showed the lowest m and mean sigma values (15.7 +/- 6.9) (P = .0001). All fractures occurred within the adhesion zone.