FRACTURE and PULL-OUT STRENGTHS of DIFFERENT MONOLITHIC POST-CORE SYSTEMS

Objectives: The objective of this study was to evaluate the fracture and pull-out strengths of different prefabricated monolithic post-core systems.
Methods: Fourty-eight extracted human permanent maxillary centrals were endodontically treated and sectioned 1 mm above the cement-enamel junction. The roots were divided into two mechanical test groups, namely fracture strength and pull-out strength. Each mechanical test group was divided into three subgroups depending on post-core systems: prefabric monolithic fiber post-core (MF) (Fibersite), monolithic zirconia post-core manufactured by CAD/CAM (MZ) (In Coris ZI) and fiber post-composite core (FC) (Rely X) control group (n=8/subgroup). The post preparations were performed using Fibersite drill for both of the MF and MZ groups, whereas fiber post drill was used for FC group. The post-core designs for all groups were standardized based on the MF group’s design. Digital impressions were taken by CAD/CAM for MZ group, and then restorations were milled. Monolithic post-core restorations for MF and MZ, and the posts for FC were cemented with resin cement (RelyX U200). Then, composite core were formed only for FC group. Mechanical tests were performed (1 mm/min) and failure types were evaluated. Data were statistically analyzed (One-way ANOVA, Benferroni).
Results: For fracture strength test, the highest values were obtained in MZ (946.33±432.26) group. The differences between MZ (946.33±432.26) and MF (633.75±136.40), and MF (633.75±136.40) and FC (392.95±81.50) were found statistically insignificant (p>.005), whereas fracture strength values between MZ and F were statistically significant (p=.001). For push-out test, statistically significant differences were found among all groups [(MF:233.92±50.39), (FC:141.16±36.28) and (MZ: 50.72±19.82)] (p=.000).
Conclusions: Post-core systems have an effect on the fracture and pull-out strengths of teeth. New generation prefabric monolithic fiber post-core system is shown to have clinical advantages as highlighed by the mechanical tests.