Influence of Post System and Geometry on Radiant Energy Transmission Through the Side of Different Prefabricated...

Adequate polymerization of resin cements in fiber post restorations depends on effective light transmission, which is influenced by post type, design, and length; however, variations in transmitted light radiant energy (TLRE) among systems may compromise bonding and long-term outcomes, and comparative evidence remains limited. This study evaluated radiant exposure and TLRE transmitted by different fiber post systems across varying post lengths. Four fiber post systems (Easy Post, RelyX Fiber Post, iLumi Super Fiber Post, and EZ-Fit Translucent Post) and a glass rod as a control group were tested (n = 40). TLRE was measured through standardized side openings at 1 mm increments after 40 s of light curing and recorded with a radiometer, while the post-microstructure was analyzed using scanning electron microscopy. Hierarchical multiple linear regression was used to assess the effects of post system and length on TLRE. TLRE differed significantly among systems (p < 0.001), with post type and length explaining a substantial proportion of variance; length was a significant negative predictor across all systems. Only 1.20-7.19% of coronal TLRE reached post surfaces. The iLumi post maintained TLRE > 200 mJ/cm² along its length, and microstructural differences were observed between smooth and serrated designs. Fiber post type, configuration, and length significantly influence TLRE, which decreases with increasing length, highlighting the importance of appropriate post selection to optimize resin cement polymerization and clinical performance.