Rehabilitation of weakened premolars with a new polyfiber post and adhesive materials

Background: Polyfiber posts used inside the root canal can help to restore the fracture resistance of weakened premolars. Aim: To assess the fracture resistance of endodontically treated premolars restored with different techniques, including the new polyfiber post (Spirapost). Materials and Methods: One hundred superior premolars were distributed into 10 groups ( n = 10): Sound teeth (G1-positive control) and experimental (G2 to G10), which received MODP cavities and canal treatment. Groups were restored as follows: G2 - unrestored (negative control); G3 - microhybrid resin (MR); G4 - flowable resin (FR) + (MR); G5 - glass fiber post (Reforpost) + MR; G6 - Reforpost + FR + MR; G7 - polyethylene fiber (Ribbond) + MR; G8 - Ribbond + FR + MR; G9 - polyfiber post (Spirapost) + MR and G10 - Spirapost + FR + MR. After 24 h, the specimens were loaded until fracture. Data were analyzed by ANOVA and Tukey's test ( P < 0.05). Results: Premolars restored with Spirapost (G9 and G10) provided the highest fracture strength ( P P > 0.05) and different from the others ( P P < 0.05). Conclusion: Fracture resistance of premolars with MODP cavities and endodontic access was recovered with the direct rehabilitation with Spirapost, regardless of the type of composite resin.