Study of the Effect of the Resin Matrix Type of Glass Fiber Posts on their Retention Within the Root Canal “An In Vitro Study”

The restoration of endodontically treated teeth relies heavily on the retention strength of fiber posts, which is influenced by their resin matrix composition. Epoxy and Bis-GMA are the most common matrices used in glass fiber posts, but their comparative performance remains debated.

This study aims to compare two types of resin matrices used in glass fiber posts in terms of their effect on post retention within the root canal.

Twenty freshly extracted lower premolars were collected, and their coronal portions were sectioned 1 mm above the cementoenamel junction. Endodontic treatment was performed on the premolars, which were then embedded in acrylic blocks. The root canals were subsequently prepared to receive the posts. The teeth were randomly divided into two groups. Group ErP: Restored with glass fiber posts containing an Epoxy resin matrix. Group BGrP: Restored with glass fiber posts containing a Bis-GMA resin matrix.

The samples were subjected to a tensile test until failure. Statistical analysis was performed using SPSS software.

Epoxy-based posts exhibited significantly higher mean tensile force (203 ± 25 N) compared to Bis-GMA-based posts (173 ± 16 N). Statistical analysis (Student’s t-test) confirmed a significant difference (P = 0.007, P 0.05), indicating superior retention for epoxy-based posts.

The superior retention of epoxy-based posts may be attributed to their rougher surface topography, enhancing micromechanical interlocking with resin cement. These findings align with prior studies supporting epoxy-based posts for high-stress scenarios but contrast with research highlighting Bis-GMA’s pre-polymerization advantages. Variability in cementation protocols and post-surface treatments may explain discrepancies in the literature.

Within the study’s limitations, epoxy-based glass fiber posts demonstrated significantly higher retention strength than Bis-GMA-based posts. Epoxy-based posts are recommended for clinical cases requiring optimal retention. Further in vitro, clinical, and microscopic studies are warranted to explore additional influencing factors.