The effect of relining with different composite resins on push out bond strength of anatomical fiber posts to root canal dentin and void formation analysed by 3D-micro CT

Abstract

Introduction: Relining fiber posts using composite resins helps the posts adapt to the anatomic space of the root canals. The aim of this study was to evaluate the effect of composite resin type on the push-out bond strength of anatomic fibers posts to intra canal dentin.

Methods and Materials: Forty-eight bovine upper incisors were prepared for post space after root canal therapy and randomly divided in to six groups. Five different types of composite resin (GrandioSO, GrandioSO Heavy Flow, X-tra Fil, X-tra base and everX Posterior) were used for relining the prepared fiber posts. In the control group, the prepared post was cemented into the post space without relining. Cervical, middle and apical cross-sections were achieved from each root and push- out test was conducted at a crosshead speed of 0.5 mm/min. One sample from each group was scanned using a micro-CT scanner which provided views from the apical, middle and coronal thirds. Data were analyzed using two-way ANOVA and post hoc test using SPSS 17 (P<0.05).

Results: Statistical analysis showed significant differences in terms of mean push-out bond strengths between different composite resin types and cross-sections (P<0.001). The mean push-out bond strength of the samples relined with Grandio SO composite resin (15.48±2.32) was significantly higher than that of other groups (P<0.05). The un-relined group had a mean push-out bond strength (5.94 ±1.45) which was significantly lower than that in other groups (P<0.05).

Conclusion: This invitro study showed us, the composite resins used for relining can affect the push-out bond strength to intra canal dentin based on their physical and mechanical properties.