Can fiber reinforcement enhance the load-bearing capacity of self-adhesive restorative materials? An in vitro study.

This study evaluated whether fiber reinforcement improves the load-bearing capacity and fracture behavior of two experimental self-adhesive restorative materials compared with conventional materials. The experimental materials were prepared by adding 20 wt% of glass fibers to the powder of a resin-modified glass ionomer cement (RMGIC) and a glass-hybrid (GH). Large MOD cavities in 70 extracted permanent molars were prepared and restored with seven restorative material groups (n = 10): conventional GIC, RMGIC, GH, experimental-RMGIC, experimental-GH, resin-based composites (RBC) and short fiber-reinforced composite (SFRC). The specimens underwent static-loading to failure after 100,000 cycles of fatigue aging. The microstructure and fracture surfaces were examined using scanning electron microscopy (SEM). One-way ANOVA was used. The incorporation of glass microfibers increased the load-bearing capacity of RMGIC from 1756 ± 394 N to 2514 ± 543 N (p < 0.05). The difference between the load-bearing capacity of experimental-GH and unmodified GH was not significant (p > 0.05). The total energy absorption prior to fracture was higher in both experimental materials compared to their unmodified equivalents. SFRC-group (3350.0 ± 569 N) demonstrated the highest load-bearing capacity among all groups. Fiber-reinforced restorations exhibited a greater proportion of favorable fracture types. SEM analysis revealed that the fibers were uniformly embedded within the cement matrix and exhibited good interfacial integration across all experimental groups. Incorporating glass microfibers significantly improved the load-bearing capacity of the RMGIC-based material and enhanced toughness in both RMGIC and GH. Fiber reinforcement also promoted more favorable fracture patterns, suggesting its potential to improve the mechanical performance of self-adhesive restorative materials.