Push-out Tests on Fiber Posts with Different Surface Treatments

Objectives: The aim of our study is to improve the adhesion strength of fiber posts by modifying the interface with various physico-chemical surface treatments. Methods: The posts studied were: Light-post and Aestheti-Plus (RTD, France). 5 groups of 10 posts were made according to the selected surface treatment : G1 (control) : G2 : Prime&BondNT /SelfCureActivator (adh) ; G3 : Sandblasting (sand) + adh ; G4 : sand + silane (sil)+ adh ; G5 : Cojet + sil + adh ; Push-out tests were carried out with a specific teflon experimental model. 6 mm high and 9 mm wide cylindrical specimens were obtained. The push-out tests were realized by a universal testing machine at a crosshead speed of 1mm/min. The push-out strength was calculated using the formula: σ = F / Π TD (F=Force, T=Thickness of the specimen and D=diameter of the post). Data were compared using ANOVA supplemented with Fisher's PLSD at a significance level of p<0.05. Results: Aestheti-Plus (MPa) : G1 = 22.5± 2.7 ; G2 = 30.1± 0.7 ; G3=34.2± 1.5 ; G4=38.6± 1.3 and G5=40.6± 3.5. Light-Post (MPa) G1 = 18.5± 2.0 ; G2 = 23.5± 2.6 ; G3=28.7± 1.9 ; G4=34.4± 2.3 and G5=31.3± 1.6. The Aestheti-Plus exhibited retention values that were significantly higher than the Light-Post independently of the surface treatment (p<0.01). Sandblasting and silane improved in any case the shear bond strength. Cojet treatment was the most effective treatment for the Aestheti-plus(p<0.05). Conclusions: the highest adhesion values were observed in group 4 and 5 posts which combine the mostly physical effect of sandblasting with the chemical effect of the silane treatment. Silanes couple the adhesive and the post by bonding with specific functional groups both to the glass fibers and to the adhesive polymer.