STATEMENT OF PROBLEM:

Cycling masticatory loads decrease the strength of particulate filler composites (PFCs) and initiate the failure process by fatigue. The life expectancy of a composite resin restoration under stress remains difficult to predict.

PURPOSE:

The purpose of this study was to determine the fracture resistance and the compressive fatigue limits (CFL) of anterior crown restorations made of a short-fiber reinforced composite resin (SFC), to investigate selected mechanical properties of the material following standard test methods, and to observe their correlation with the CFL.

MATERIAL AND METHODS:

Specimens (n=10) were fabricated either from SFC (everX Posterior, GC Corp) or PFC (G-ænial anterior, GC Corp). The properties investigated were flexural strength (FS), compression strength (CS), diametral-tensile strength (DTS), and single-edge-notched-bend fracture toughness (FT) following ISO standards. Fracture resistance was determined by static load (n=10) and the CFL at 10000 cycles was determined using a staircase approach (n=20), both on anterior composite resin crowns. The results were analyzed with 1-way ANOVA (α=.05) or 2-way ANOVA (α=.05) followed by a Tukey B post hoc test and the Pearson-correlation analysis.

RESULTS:

The SFC crowns had higher fracture resistance (954 ±121 N) than the PFC crowns (415 ±75 N) (P<.001) and higher CFL (267 ±23 N) than the PFC crowns (135 ±64 N) (P<.001). SFC revealed also higher FT (2.6 ±0.6 MPa·m(1/2)) than the PFC (1.0 ±0.2 MPa·m(1/2)) (F=69.313, P<.001). A significant correlation was observed only between the FT and the CFL (r(2)=0.899; P<.001).

CONCLUSIONS:

SFC crowns showed good performance under static and fatigue loading. FT was the only in vitro test method that filtered as a clinically relevant parameter.