The comparison and evaluation of push-out bond strength of surface treated (sandblasting and Nd

Abstract

Fiber-reinforced composite posts are one of the fundamental elements in restoring endodontically treated teeth which improve retention of the coronal part of the restoration and increase strength of final restorations. Optimum adhesion between the post and root canal dentin is a basic concept which needs appropriate treatment procedure applied on the post surfaces. There are few methods to condition the surface of such posts, including chemical and physical procedures. Air abrasion is a physical conditioning method and acid etching and silanization are examples for chemical surface treatments. Objectives: The aim of present study was to investigate the effect of laser irradiation as a new surface conditioning method and air abrasion technique on push out bond strength of quartz fiber composite posts to root canal dentin. Methods and materials: In this in vitro study 60 single-rooted extracted premolars free of defects were sectioned perpendicular to their long axes at the cemento-enamel junction. After root canal preparation and rinsing, canals were obdurated using AH26 sealer and Gutta-percha. The post spaces were prepared 24 hours after completing endodontic procedures. Posts and teeth samples were divided in three groups. In first group 20 quartz fiber posts were treated with Nd: YAG laser, wave length of 1064 nm, energy of 100 m J/pulse, power of 2 watt and 2 Hz frequency. In The second group the posts were conditioned with sandblast alumina particles using DENTO-PREP Aluminum Oxide micro blaster. This was performed with 50 ? meter alumina particles at 2.5 bar pressure for 5 seconds and from a distance of 30 mm. The conditioned posts were cemented into the root canals by a self-etch dual-cure resin cement (Panavia F2.0).in the third group the fiber posts were cemented to the root canal without any conditioning. The specimens were attached to the arm of a low-speed saw and sectioned perpendicular to the long axis under water cooling. From each specimen, 3 post/dentin sections (cervical, middle, and apical) were obtained, each 3 mm thick. A whole number of 180 specimens were undergone the Push-out test using a customized stainless steel push-out device. Loads were applied with a universal testing machine at a crosshead speed of 0.5 mm/min. The peak force, at the point of extrusion of the post segment from the test specimen, was taken as the point of bond failure and recorded in Newton (N). Three samples from each group were randomly selected and SEM images were captured to evaluate interactions on post surfaces. Other samples were observed under stereo microscope for evaluation of bond failure modes. Mean values were compared with a 2-way ANOVA, followed by a multiple comparisons test performed using a Tukey honestly significant difference (HSD) test to evaluate the different sections and different treatment methods. Statistical significance was set at the p < 0.05 level.data analysis was done by Spss (Ver.19). Results: Mean values STD of push-out bond strength test for 3 groups of the study are Nd: YAG laser: 46.4646 9.74742; Sandblast: 27.6128 11.37682 and Control group: 26.4015 8.30417. Push-out bond strength values in samples prepared by Nd:YAG laser was significantly more than air abraded samples and samples of the control group (p<0.05).Push-out bond strength values in samples of the abrasion group and control group were not significantly different.SEM images justifies the statistical results. Conclusion: Considering the limitations of the present study; Nd: YAG laser irradiation over graphite marked areas could be offered as a surface treatment method for quartz fiber composite posts. Air abrasion technique with the parameters used in this study had no effect on bond strength of posts to root canal dentin.