Fracture Resistance of Anterior Crowns Reinforced by Short-Fiber Composite

The aim of this study was to investigate the load-bearing capacity of anterior crowns made of different commercial particulate-filled composites (PFCs) and reinforced by a core of short-fiber composite (SFC) (bilayer structure). Four groups of composite crowns were fabricated for an upper central incisor (n = 20/group). Two groups were made of chair-side PFC composites (G-aenial anterior, GC, Japan and Denfil, Vericom, Korea) with or without SFC-core (everX Flow, GC). One group was made of laboratory PFC composite (Gradia Plus, GC) with or without SFC-core. The last group was made of plain SFC composite polymerized with a hand-light curing unit only or further polymerized in a light-curing oven. Using a universal-testing device, crown restorations were statically loaded until they fractured, and failure modes were visually investigated. Analysis of variance (p = 0.05) was used to evaluate the data, followed by Tukey’s post hoc test. Bilayer structure crowns with SFC-core and surface PFC gave superior load-bearing capacity values compared to those made of monolayer PFC composites; however, significant differences (p < 0.05) were found in the chair-side composite groups. Additional polymerization has no impact on the load-bearing capacity values of SFC crowns. Using SFC as a core material with PFC veneering composite to strengthen anterior crown restorations proved to be a promising strategy for further testing.