Fracture Resistance of Endodontically Treated teeth Restored with Esthetic Posts

Objectives: This study compared the effect of three esthetic post systems with different modulus of elasticity on the fracture resistance and fracture patterns of endodontically treated teeth with structurally compromised and normal roots.

Methods: Forty five extracted and root canal treated central incisors were assigned to 2 main experimental groups called "narrow" and "flared" canals. Narrow-canal group divided into 2 and flared-canal group, divided into 3 experimental subgroups (n=9). For narrow-canal subgroups, post spaces were prepared with the corresponding drills to restore with quartz fiber double taper light posts (D.T. Light-Post; RTD) [subgroup A] and zirconia posts (CosmoPost;Ivoclar) [subgroup B]. For the flared-canal subgroups, thin–walled canals were simulated, and restored with quartz fiber double taper light posts[subgroup C], quartz fiber double taper light posts inserted within the polyethylene woven fibers (Ribbond;Ribbond,Inc) [subgroup D] and zirconia posts[subgroup E]. All posts were cemented with dual–polymerizing adhesive resin cement (Panavia F; Kuraray).After restoration of access cavity with composite and thermocycling, compressive load was applied to the palatal surface of tooth until fracture. Mean failure load values were analyzed using One-way ANOVA and Tukey test (P<0.05).Mode of failure was evaluated with Fisher exact test (P<0.05).

Results: The mean failure loads ± SD were 678.55±90.86, 603.44±68.66, 638.22±93.71, 732.44±81.78, and 573.66±91.340 N for subgroups A to E, respectively. Subgroup D exhibited significantly higher resistance to fracture compared to subgroups B, C and E (P<0.05). Subgroup E showed significantly less fracture resistance compared to subgroups A and D (P<0.05). Subgroups B and E showed more root fracture compared to subgroups A, C, and D (P=0,004).

Conclusion: Significantly higher fracture resistance was observed in flared root canal treated teeth restored with quartz fiber double taper light posts + polyethylene woven fibers. Zirconia posts showed lower fracture resistance and significantly more root fracture compared to fiber posts.