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 < 0.05), similar to sound teeth (G1), regardless of the composite resin. Intermediate values were achieved by G3, G4, G5, G6, G7, and G8, which were similar (P > 0.05) and different from the others (P < 0.05). Inferior values were found in G2 (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.