IN VITRO WEAR OF THREE BULK FILL COMPOSITES AND ENAMEL

What is it about?

Introduction: This in vitro study aimed at testing the hypotheses that (1) there is no difference in wear in vitro among 3 bulk-fill composites investigated and their respective antagonists, and (2) the tested bulk-fill wear is not different from enamel. Methodology: X-tra fil (Voco; [X]), Tetric-N-Ceram Bulkfill (Ivoclar Vivadent; [T]), QuiXX (Dentsply; [Q]), and enamel [E] specimens (Ø=8 mm, depth=1.5 mm, n=8/material) were subjected to wear in a chewing simulator (CS 4.8, SD Mechatronik) with steatite antagonists (Ø=6mm). 1.2×105 cycles (0-49 N, 0.7 mm lateral movement, 1 Hz) were performed while simultaneously thermocycling (5/55°C) every 90 s. The volumetric wear of the materials was measured with a 3D laser scanner. Results: The total wear of bulk-fills was: [X]: 0.64±0.07 mm3; [T]: 0.66±0.08 mm3; [Q]: 1.58±0.14 mm3. The total wear of enamel (0.24±0.03 mm3) was significantly lower than that of the bulk-fills (p<0.0001). The total wear of the antagonists was: [X]: 0.32±0.02 mm3; [T]: 0.24±0.04 mm3; [Q]: 0.27±0.02 mm3; [E]: 0.12 ±0.01 mm3. The wear of the antagonists by [X] was significantly higher than by [T] and [Q] (p<0.001). Enamel produced the lowest wear of the antagonists (p<0.0001). The wear was linear between 5×103 and 1.2×105 wear-cycles. A negative correlation between the wear of the composite materials and that of the antagonists was found. Conclusion: In vitro wear of Tetric-N-Ceram Bulkfill was in the expected range and equal to X-tra fil. QuiXX wear was 2.7 times higher. The antagonist wear was significantly lower, less than 50% of the wear of the composites and the enamel. Both hypotheses were rejected. Keywords: chewing simulator, wear, bulk-fill composite, thermocycling, enamel.

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