Post-and-Core Buildup Techniques with Short Fiber-Reinforced Composite and Polyethylene Fiber: In Vitro Evaluation of the Fracture Load and Mode of Failure

The aim was to evaluate, in vitro, the fracture load of single-rooted teeth restored using post-and-core techniques combining short fiber-reinforced composite (SFRC) and polyethylene fiber (PEF) compared with the conventional technique of post-and-core buildup using fiberglass posts (FGPs). Thirty-six single-rooted anterior teeth (12 mm root length) were assigned to three groups (n = 12): Group 1 (FGP + conventional composite resin), Group 2 (SFRC), and Group 3 (PEF + SFRC). All specimens received composite resin crowns, were subjected to 1,000,000 mechanical cycles (100 N, 45°), and were then tested for fracture resistance. Failure mode was assessed visually. After mechanical cycling, no fractures, chipping, cracks, or restoration displacement were observed in any specimen. According to the Kruskal–Wallis test and Dunn’s post hoc test with Bonferroni correction, Group 2 (946 N) showed the highest fracture load, with no significant difference from Group 3 (820 N) (p > 0.05). The lowest median was observed in Group 1 (513 N), which differed significantly from the other two groups (p < 0.05). Irreparable failures occurred in Group 1 (75%), Group 2 (50%) and Group 3 (59%). It was concluded that post-and-core technique using SFRC, either alone or in combination with PEF, is a viable and mechanically superior alternative to FGP for rehabilitating single-rooted teeth without a ferrule.