Evaluation of the effect of fiber posts with different surface treatments on the core fracture resistance.

Aim: This study aimed to determine the effect of different surface treatments applied to the coronal region and the presence of ferrule on the fiber post-composite core fracture strength of teeth to be restored with fiber post. Method: 120 extracted human premolar teeth were divided into 2 groups (n=60). While 2mm ferrule was formed in one group, no ferrule was applied in the other group. The samples were randomly divided into 4 subgroups according to different surface treatments (n=15). The samples in these groups were treated with 9.5% Hydrofluoric (HF) acid for 20 seconds, 150mJ, 10 Hz, 1.5 W Er,Cr:YSGG laser and 20 seconds 120 µm Al2O3 sandblasting, and no surface treatment was applied to the control group. After the surface treatments 5000 thermal cycle processes were applied to all samples. All fiber post specimens were cemented into the teeth with dual cure resin cement. After the core was formed, the samples were tested with a conventional testing device at a speed of 1 mm/min at a 45° angle to the long axis of the teeth. The data obtained were evaluated with the two-way repeated measures ANOVA test. The p value was evaluated as 0.05 in all analyzes. Results: The group with the highest fracture strength was found to be the control group (696.01±135.09 N) treated with ferrule, and the acid group without ferrule (276.25±59.99 N) the lowest. The fracture strength of the ferrule specimens is higher than the specimens without ferrule, but the change in the groups is similar. According to the classification of fractures in the post-core teeth, 55% of the specimens with a ferrule were repairable, while the repairable rate of fractures in the specimens without a ferrule was 43.67%. Conclusion: Ferrule application increased fracture strength in teeth restored with root canal treated post-core method. All surface treatments applied to the core parts of the fibers, on the other hand, deteriorated the structure of the fiber, weakened its bonding and reduced its fracture resistance. Keywords: Post-core, Er,Cr:YSGG, hydrofluoric acid, sandblasting, ferrule