Propriedades mecânicas e químicas de resinas compostas fluidas com diferentes estratégias adesivas

Abstract

Flowable composite resins are widely used in restorative dentistry, and more recently, self-adhesive flowable composites have been introduced, eliminating the need for separate adhesive systems. This study compared the degree of conversion and surface microhardness of a conventional flowable composite (YFlow) and a self- adhesive flowable composite (YFlow SA), both from the Yller brand. Specimens (n = 5 per group) were fabricated with standardized dimensions (5 mm in diameter and 2 mm in thickness). The degree of conversion was evaluated using FTIR spectroscopy, analyzing the absorption band intensity at 1636 cm−1 before and after polymerization. Microhardness was measured using a Vickers microhardness tester with a 50 g load for 45 seconds. Data were statistically analyzed using Student’s t-test (α = 0.05). The results showed that the self-adhesive resin had significantly higher values in both degree of conversion (73.6% ± 2.8) and microhardness (39.9 HV ± 1.9) compared to the conventional resin (56.2% ± 4.6 and 36.7 HV ± 2.2, respectively), with p < 0.05 for both comparisons. Within the limitations of this study, it can be concluded that the self- adhesive flowable resin performed better in the evaluated properties. Differences in its chemical composition are likely responsible for these results. However, further studies are needed to assess other material properties as well as clinical studies to evaluate the performance of these resins under real clinical conditions.