The effect of luting cement thicknesses on the push-out bond strength of the fiber posts

Objective. The aim of this study was to evaluate the effect of luting cement thicknesses on the push-out bond strength of the fiber posts. Materials and methods. Sixty human maxillary canine teeth were endodontically treated. Post spaces were prepared and root specimens randomly divided into three groups: Group 1: etch-and-rinse (Variolink II/Exite DSC), Group 2: self-etch (Panavia F2.0/ED primer) and Group 3: self-adhesive (Clearfil SA Cement). Then each group was divided into four sub-groups according to the cement thickness, as follows: Sub-group 1: 0.35 mm, Sub-group 2: 0.25 mm, Sub-group 3: 0.15 mm, and Sub-group 4: 0.05 mm. Three slices of 1 mm thickness were obtained from each root specimen (n = 15). Push-out tests were performed and data was analyzed with two-way ANOVA and Tukey tests. Results. The etch-and-rinse system (Variolink II) had a significantly higher bond strength compared with the other systems (p < 0.05). The thickest cement group (0.35 mm) had a significantly lower bond strength compared with the 0.15 and 0.05 mm groups in the etch-and-rinse and self-adhesive groups (p < 0.05). In the self-etch group, the cement thicknesses did not significantly affect the bond strength (p > 0.05). Conclusions. The etch-and-rinse system offered better bonding to root dentine than the self-adhesive and self-etch systems. The increases in cement thickness significantly reduced the bond strength of fiber posts to root dentine for both the etch-and-rinse and self-adhesive systems.