Purpose: The aim of this study was to evaluate the effects of the different sized alumina particles (50 and 150 mu m) and tribochemical silica-modified alumina particles (110 mu m) on titanium (Ti) surface to identify the most effective method of increasing the bond strength between porcelain and Ti. Materials and Methods: Thirty rectangular plates (15 mm x 50 mm x 1 mm) of commercially pure Ti (Cp Ti) Grade 5 (GC Dental Industrial Corporation, Tokyo, Japan) were divided into three groups for different surface modification procedures (n = 10). Ti bonder porcelain, opaque, and dentin layers were fired separately on Ti plates. All specimens were placed in a bending jig for four-point bending test. The load and crosshead displacement data were collected to calculate the strain energy release rate as a G value. Results: Lowest mean G values in J/m(2) were in the group sandblasted with 150 mu m Al2O3 particles (Group 2) (18.6 +/- 5), followed by the group sandblasted with 50 mu m Al2O3 particles (Group 3) (20.8 +/- 6.1) and the group sandblasted with 110 mu m silicoated Al2O3 particles (Group 1) (24.5 +/- 4.1). The one-way ANOVA and Bonferroni post hoc tests indicated that there was a statistically significant difference between Group 1 and Group 2 (P < 0.05). There were also no statistically significant differences between Group 1 and Group 3 and Group 2 and Group 3 (P > 0.05). Conclusion: The size of alumina particles is not a factor that is directly effective in enhancing the bond strength of Ti-porcelain systems. The bond strength of Ti-porcelain systems can be extremely improved by the application of sandblasting with silica-coated alumina particles.