Investigation of the fracture strengths of three different post-core systems and evaluation of the stress distribution using finite element analysis

Objective: The aim of the present study was to investigate the fracture resistance of polyether ether ketone (PEEK), glass fiber and zirconium oxide post-core restorations and stress distributions of post-cores and roots by using finite element analysis (FEA). Method: Post cavities of 7.5 and 10 mm depth were formed with 1.4 and 1.6 mm diameter drills at maxillary central incisors (N=120). Glass fiber, zirconium oxide and PEEK posts were applied to post cavities (n=10). Coping was generated for samples. Static load was applied on the long axis of tooth with 45 inclination with universal tester. FEA 100 N force was applied along to long axis of the tooth at 45 angle. Von Misses stress values were recorded and images were obtained. Fracture resistance data were statistically evaluated by using One-Way ANOVA and LSD test. Results: When fracture resistance were evaluated, the post dimensions didn't show statistically significant difference in PEEK posts (p> 0.05). Among zirconium oxide groups, the lowest fracture resistance was observed in short-narrow group and the result was statistically significant. The highest fracture resistance in glass fiber groups was seen in long-wide groups. The PEEK's fracture resistance was significantly lower than glass fiber in other sizes except short-wide group. The highest Von Misses value of posts was seen in PEEK post-core (32.76 MPa). These values were 0.80 MPa and 21.17 MPa for glass fiber and zirconium oxide post. The highest Von Misses values in roots were in glass fiber post model (72.79 MPa), whereas 69.01 MPa and 58.22 MPa in zirconium oxide and PEEK posts. Conclusion: PEEK posts showed adequate fracture resistance. The highest value of fracture resistance was observed in glass fiber post groups. The highest Von Misses value of root which was caused by PEEK post-core was lower than the all other models. Key words: post-core, PEEK, CAD/CAM, glass fiber, zirconium oxide