Objective: The purpose of this study was to investigate the effects of flowable composites applied between porcelain surface and composite resin in porcelain repair procedures.

Methods: The surfaces of 40 feldspathic porcelain specimens fired in metal cylinder ingots were standardized using 320 grit SiC paper. Then the specimens were sandblasted with 50 µm  (2.5 atm for 3 s). The etching of porcelain surface was performed with 4% hidroflouric acid gel for 4 minutes as recommended by the manufacturer. After applying silan coupling agents (Porcelain Primer; Bisco) and adhesive (One-step; Bisco) the specimens were divided into 4 groups, containing 10 samples each. Three different flowable composites (Tetric flow, Vivadent;  Filtek flowable, 3MESPE; Aelite Flo LV, Bisco) were applied with brush to the experimental groups. In the control group flowable composite was not used. Hybrid composite (Valux plus; 3MESPE) was bonded to the porcelain surface using translucent plastic ring. Following storage in distilled water at 37ºC for 1 day, the specimens were subjected to  shear testing at 0.25mm/min and shear bond strength were determined in MPa.  Statistical analysis of the data was accomplished by analysis of variance (ANOVA). A Scheffe's test was used for all groups compared at the  95% confidence level.

Results: Means with the same supercript letter are not statistically different at p> 0.05.( mean±sd, MPa). Filtek flowable: 16.40±4.19 ^a, Tetric Flow:13.75± 4.0 ^a, Aelite flo LV: 15.03± 4.34 ^a Control:15.37 ±2.20 ^a

Conclusion: A statistically significant difference was not found both between the groups with flowable composite and the group without flowable composite. No effect has been found on the shear bond strenght to porcelain by using flowable  composites for repair.