Comparative Evaluation of Push-out Bond Strength between Surface-Treated Glass Fiber Reinforced Composite Resin Post and CAD/CAM Milled Polyetheretherketone Post: An In vitro Study

Abstract

Background: Endodontically treated teeth with extensive coronal structure loss require dependable post-and-core restorations. Prefabricated glass fiber reinforced composite resin (FRC) posts are in routine use, while custom CAD/CAM milled polyetheretherketone (PEEK) posts are an emerging alternative with potentially superior bonding and biomechanical characteristics. Aim: To evaluate and compare the push-out bond strength of surface-treated FRC posts and CAD/CAM milled PEEK posts across coronal, middle, and apical root thirds. Materials and Methods: Twenty-two extracted human maxillary central incisors were endodontically treated and randomly allocated to Group I (n = 11, prefabricated FRC posts) and Group II (n = 11, CAD/CAM milled PEEK posts). Both groups underwent identical surface treatment — 50 µm Al₂O₃ sandblasting followed by silane application — and cementation with dual-cure self-adhesive resin cement. Cemented specimens were stored in distilled water at 37°C for 24 hours prior to testing (no thermal cycling or fatigue loading). Three transverse 2 mm slices per specimen (coronal, middle, apical) were tested on a universal testing machine. Descriptive statistics, independent samples t-test, one-way ANOVA for intragroup regional comparisons, and Bonferroni post hoc analysis were performed (SPSS v28.0.1; significance threshold p < 0.05). Results: Group II (PEEK) demonstrated significantly higher push-out bond strength than Group I (FRC) at all three root thirds: coronal (11.86 ± 1.14 vs 7.74 ± 1.60 MPa; t = −6.968; p < 0.001), middle (12.33 ± 0.75 vs 7.53 ± 0.92 MPa; t = −13.382; p < 0.001), and apical (10.99 ± 0.69 vs 6.36 ± 0.80 MPa; t = −14.536; p < 0.001). One-way ANOVA revealed significant intragroup regional variation in both Group I (F(2,30) = 4.497; p = 0.020) and Group II (F(2,30) = 6.566; p = 0.004). Bonferroni post hoc analysis identified the middle-to-apical contrast as the only significant pairwise difference within each group (Group I: p = 0.014; Group II: p < 0.001). Coronal-to-middle and coronal-to-apical comparisons were not significant after correction in either group. Conclusion: CAD/CAM milled PEEK posts exhibit significantly superior push-out bond strength compared with prefabricated FRC posts following equivalent dual surface treatment. The apical third represents the consistently weakest bonding zone in both post systems. These findings support the clinical use of CAD/CAM milled PEEK posts as a viable alternative for restoring endodontically treated teeth, with clinical implications for improved retention and reduced root fracture risk in heavily restored endodontically treated teeth.