OBJECTIVES: The aim of this study was to evaluate the polymerization depth of two new composite resins compared to a standard hybrid composite resin.

MATERIALS AND METHODS: For each of the three composite resins used (QuixFil, Dentsply, Germany; Adamant, Vivadent, Germany; Tetric-Ceram, Vivadent, Germany) two groups with 10sec and 20sec polymerization time respectively, 10 samples each, were prepared. The specimens were polymerized using two different LED polymerization units (Ultra-Lume 5, Ultradent, USA; Smartlite, Dentsply, Germany) and had a thickness of 8mm. Twenty-four hours after polymerization they were embedded in acrylic resin and separated in the middle in the vertical axis. On the section plane Knoop-microhardness was measured every 1mm, starting 0.5mm below the top-surface.

RESULTS: Microhardness measurements were able to be done up to a depth of 3.5mm for Tetric-Ceram, 4.5mm for Adamant and 7.5mm for QuixFil. Two way ANOVA showed a significant influence of the three materials and the two polymerization units on the microhardness (p=0.0001). Tukey′s studentized range test showed that QuixFil and Adamant were significantly harder compared to Tetric-Ceram when polymerized with Ultra-Lume for 10sec, while QuixFil was significantly harder than Tetric-Ceram when polymerized for 20sec with Smartlite. Tetric-Ceram reached 80% of the surface-hardness at a depth of 2.5mm (24.74 N/mm² ± 4). Adamant had a microhardness of 80% of the surface-value (44 N/mm² ± 6.5) at a depth of 4.5mm (10sec), while QuixFil had a microhardness of 85.5% of the surface-value (32 N/mm² ± 3.3) at 6.5mm (10sec).

CONCLUSIONS: The new composite materials tested in the present study showed a better polymerization rate compared to a standard hybrid composite using two LED curing units.

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