Mechanical Properties of Composite Core Build-Up Materials – a Comparative Study

Objectives: To compare the mechanical properties of dedicated core build-up materials and bulk-fill resin composites as restorative options for core build-up materials.
Methods: The flexural modulus (FM), flexural strength (FS), modulus of resilience (R), water sorption (WS), and solubility (SO) were evaluated for three dual-cure resins: CosmeCore DC Automix (Cosmedent) – CCC, Clearfil DC Core Plus (Kuraray)-CCP, and MultiCore Flow (Ivoclar Vivadent)- CMC and two bulk-fill resin composites (Filtek One Bulk Fill Restorative - BFO and Filtek Bulk Fill Flowable - BFF from 3M ESPE). Additionally, a control group consisted of a conventional resin composite Filtek Supreme Ultra (3M ESPE) - FSU. All tests were conducted according to ISO 4049. For mechanical properties, beam-shaped specimens (25 mm x 2 mm x 2 mm, n=12) were fabricated and subjected to three-point bending using an Instron machine. WS and SO were determined for disc-shaped samples (15 mm x 1 mm, n=5) by desiccation. Samples were weighed until a constant mass (m1) was achieved, followed by immersion in deionized water to calculate WS (m2). Subsequent desiccation yielded m3. Data were statistically analyzed using one-way ANOVA and Tukey post-hoc tests (α = 0.05).
Results: With regards to flexural strength, CCC and BFO exhibited significantly high values (137.77 and 134.57, respectively), while FSU demonstrated the lowest value (109.15). FSU showed the highest value for water sorption and resilience. Regarding solubility, no statistically significant differences were observed among all groups. Concerning flexural modulus, BFF exhibited significantly lower results (4.69), while FSU and BFO demonstrated the highest values (8.91 and 8.53).
Conclusions: The CosmeCore build-up material and Filtek One Bulk Fill demonstrated superior results in most tests, showing excellent properties for core-build-up.