Evaluation of the the bond strength between different surface treatments applied fiber reinforced composite post and root canal dentine wi̇th pust out test

Objective: The aim of this study is to investigate the effect of the different surface treatment of fiber reinforced composite post and different root canal solutions with laser activation on root dentin to post-dentin bond strength. Method: For the study, 200 pieces permanent single rooted premolar teeth were selected. The teeth were cut from the enamel- cementum border with a high-speed saw. In all teeth, the length of the work was determined as 1 mm shorter than the apical foramen and the root canal preparation was done with rotary system. Before the post preparation all fiber posts divided to 5 groups according to different surface conditioning procedures (sand blasting with Al2O3, etching with hydrofluoric acid, Er; Cr; YSGG laser (1,5 W, 20 Hz, 20 seconds), Nd:YAG laser (100 mj, 1W, 20 seconds), untreated surface). Then the fiber posts which the surface treatments were finished divided into 3 groups (%2 NaOHCl, %17 EDTA, %17'lik EDTA+LAI (25 mJ, 20 Hz 0,50 W) (320-mm radial firing tip RFT3, 5mL, 60 seconds)) according to root canal irrigation procedures. Resin cement was sent to root canal by rotary instrument then fiber posts were placed into root canal by finger pressure. The cement was polymerized according to the manufacturer's instructions. Samples were subjected to 5000 cycles of thermal cycling at 5-55 oC prior to push-out strength testing. Three horizontal sections of 1 mm thickness were obtained from the coronal, middle and apical 1/3 of each root by using a diamond disc under the cutting device and water cooling. For push - out strength test with universal test machine, 1 mm / min in apico - coronal direction, 1 mm diameter stainless steel cylindrical tip was used to force to the connection until failure occurred between dentin and resin. This force was recorded in Newton and the bond strength values were converted to megapascal (MPa). Fracture types were examined at × 32 magnification in stereomicroscope and Scanning Electron Microscopy (SEM) analyzes were performed by selecting random samples from coronal, middle and apical to the root canal surface treatments. Statistical analysis of surface treatments was performed by using ANOVA (one way), TUKEY, Tamhane T2, welch test, F tests Results: The highest bond strength values were determined as root canal EDTA (apical) -fiber post Er, Cr: YSGG laser group (9,53 ± 2,75) MPa, and the lowest bond strength value was root canal NaOCl (middle)-fiber post sand blasting group (3.99 ± 0.78) MPa. In the laser irradiation groups, dentin tubule mouths were completely opened in all parts of the tooth. Rough areas in Er, Cr, YSGG laser groups in fiber post surface treatments were observed on SEM images. Micro retantive areas formed by the presence of rough areas have provided high bond strength values. Conclusions: According to the results of the study, the use of fiber post surface treatments with different root canal irrigation techniques; can improve the bond strength between fiber post - resin cement – root canal dentin.