Aim
This study aimed to assess the polymerization effectiveness of bulk-fill composite resins in longitudinal microhardness.
Methods
Blocks of bulk-fill composite resin with thicknesses of 6 mm were analyzed with Vickers microhardness. The resin blocks were divided into two groups (n=6): resin AURA and OPUS. The microhardness test was performed before (base and top) and after (longitudinal microhardness) sectioning the blocks at distances of 2 mm, 4 mm, and 6 mm from the top of the block. The mean microhardness values were tabulated and subjected to ANOVA followed by Tukey’s test (p<0.05).
Results
The OPUS bulk-fill resin samples presented microhardness means of 55.9 kgf/mm2, 53.7 kgf/mm2, and 49.3 kgf/mm2, the AURA bulk-fill resin samples presented microhardness means of 57,02 kgf/mm2, 55,86 kgf/mm2 e 51,77 kgf/mm2 for the distances of 2 mm, 4 mm, and 6 mm, respectively. Tukey’s statistical test showed a significant difference in microhardness values at different distances of 2 mm, 4 mm, and 6 mm (p<0.001) for each resin. Although there was a statistically significant difference within and between the groups assessed, all samples showed polymerization effectiveness when comparing the top and base of the block.
Conclusion
Polymerization was effective in different thicknesses (2 mm, 4 mm, and 6 mm) in both resins studied. The microhardness ratio was adequate when comparing the base and top.
Keywords
Composite resins; Hardness; Polymerization