Materials and Methods: 7 different composite resins (3 self-cured (SC), 2 light-cured (LC) and 2 dual-cured (DC)) were tested in a 3-point bending test following storage under 5 different storage conditions (10 min dry at 37°C/ 2h, 24h and 7d in deionized water at 37°C/ 7d thermocycling 5000 x, 5-55°C). In addition, flexural properties of DC composite resins were determined after omission of the light-curing step. Data were statistically analyzed using ANOVA (á=0.05).
Results: SC composite resins showed the lowest (FS: 60.8 ± 6.2 to 125.7± 8.1 MPa and FM: 1.4 ± 0.4 to 12.4 ± 1.2 GPa), whereas LC materials showed highest mechanical strength (FS: 83.7 ± 6.1 to 158.7± 6.5 MPa and FM: 4.1 ± 0.5 to 20.0 ± 1.6 GPa). DC composite resins showed lower FS and FM values when omitting the light curing step (FS: 63.2 ± 3.7 to137.3 ± 8.3 MPa and FM: 1.9 ± 0.5 to 7.9± 0.3 GPa). Material as well as storage had a significant influence on the mechanical properties (p<0.05).
Conclusions: Within the limits of this study, it can be concluded that LC core-buildup materials should be preferred for daily practice whenever possible due to higher mechanical strength. For DC composite resins, light curing is mandatory to achieve adequate strength.