Modulus of Post Affects Fracture Resistance of Endodontically Treated Tooth

Objectives: Fiber reinforced post restored endodontically treated tooth (ETT) was considered as the monobloc configuration. The purpose of this study was to evaluate the different modulus of post on fracture resistance of ETT. Methods: Twenty four mandibular extracted premolars were decoronated at CEJ and endodontically treated. The root was filled with gutta percha and Grossman formula sealer using lateral condensation technique. Post space of 10.5 mm was performed using gate gridden drill and final enlarged with cylindrical bur with diameter 1.5 mm. The specimens were randomly divided into 4 groups with n=6. Three experimental fiber reinforced posts with glass fiber volume content of 0(E3, E=3GPa), 20 (E17, E=17GPa) and 40 (E31, E=31GPa) % and Ag-In alloy (E70, E= 70GPa) post were used as post. All types of post have parallel configuration with the same diameter of 1.5 mm. All posts were luted into the post space using Panavia F 2.0 as per manufacturer's recommendations. The SE bond was used as bonding agent for coronal part of the specimen and later built up using Clearfil Photocore (E=17GPa). Specimens were stored in 37°C water 24 hours prior to the test. The specimens were loaded at 45° on the buccal cusp using a universal testing machine (Instron 8872) with a cross head speed of 2 mm/min. The load in Newton (N) of all specimens were analyzed using one way ANOVA and Tukey's multiple comparison at p<0.05. Results: Means (sd) of fracture resistance were 1126.4(378.8), 952.44(169.5), 857.68(230.8) and 566.7(174.8) N for E17, E31, E70 and E3 respectively. Tukey's revealed that fracture resistance of E17 group was significantly greater than E3 group. Conclusion: Fiber reinforced composite post (E17) which has modulus close to core built up material and dentin demonstrated greater fracture resistance. Mode of failure of this group was restorable.