Fracture Toughness of CAD/CAM Resin-Based Materials vs. Direct Composite Resins: A Scoping Review

Objective: To compare the fracture toughness of CAD/CAM resin-based restorative materials and direct composite resins. Materials and Methods: A systematic search was conducted in July 2025 across PubMed/MEDLINE, EBSCO, Scopus, ISI Web of Science, and grey literature. Eligible studies were only in vitro investigations evaluating fracture toughness of direct composite resins and CAD/CAM hybrid materials. Study selection, data extraction, and risk-of-bias assessment were performed independently by two reviewers. A systematic review and meta-analysis were not performed due to methodological heterogeneity, and findings were synthesized qualitatively. Results: Fifty-two studies met the inclusion criteria, including 16 assessing CAD/CAM restorative materials. Considerable variability in fracture toughness values was observed, even within the same material type. Most studies were judged to present a medium risk of bias. Short fiber-reinforced composites exhibited higher fracture toughness, whereas other CAD/CAM resin-based materials showed values comparable to direct composites. Conclusions: Current evidence does not confirm superior fracture toughness of CAD/CAM resin-based materials compared with direct composites. Short fiber-reinforced composites appear to offer improved resistance to crack propagation. Standardized testing protocols are needed to enable more reliable comparisons.