Resistance Against Pull-out Force of Prefabricated Coated FRC Posts

Purpose: To investigate the effect of a prefabricated tribochemical coating of FRC (fiber-reinforced composite) posts with and without aging on the pull-out forces compared to posts without conditioning. Materials and Methods: Post space preparations were performed on 108 extracted anterior teeth. Thirty-six uncoated FRC posts (Dentin Post) and 72 prefabricated tribochemically coated FRC posts (Dentin Post Coated) were used at a length of 12 mm. Thirty-six of the coated posts were thermally aged. FRC posts (n = 9) were placed using Dentin Build or Multi Core Flow foundation composite resins or Panavia F2.0 or RelyX Unicem resin cements. Following water storage (37 degrees, 24 h) and thermocycling (5000 cycles, 5 degrees to 55 degrees C, 30 s), pull-out force testing was performed. Fracture modes were assessed using a light microscope. Data were analyzed statistically (1-way and 3-way ANOVA, Bonferroni-Dunn correction, alpha = 0.05). Results: Significantly higher pull-out forces of posts luted with Panavia F2.0 were observed for the coated and coated/aged FRC posts compared to the unconditioned posts (control group, p < 0.001). The pull-out forces of tribochemically coated FRC posts luted with Multi Core Flow were significantly lower than of coated posts luted with Panavia F2.0 (p < 0.001). Coated/aged FRC posts exhibited similar pull-out forces for the tested luting composite resins (p > 0.05). Except for Dentin Build (coated posts), more mixed or cohesive fractures were assessed for coated and coated/aged FRC posts than for unconditioned FRC posts. Conclusion: Prefabricated tribochemical coating of FRC posts provided a stable interface between coating and post and remained stable over time.