In vitro evaluation of the base/top hardness ratio and push-out bond strength between a diatomite-containing composite resin and a bulk-fill composite resin
Composite resins. Evaluation of mechanical properties. Toughness. Aging. Diatomaceous earth.
After the advent of bulk-fill resins, characterized by their use in a single increment, the restorative composite containing diatomite in its inorganic content appeared, marketed as Zirconfill®. However, the scarcity of data that scientifically validate the benefits of diatomite for the physical properties of this composite resin makes it imperative to carry out new studies, especially regarding the use of Zirconhill in semi-direct restorations, whose indication requires materials that support masticatory loads. Objective: To evaluate in vitro the base/top hardness ratio (B/T) and push-out bond strength (RU) between a composite resin containing diatomite and a bulk-fill composite resin after 24 hours and after 6 months of aging. in water. Materials and methods: Twenty-eight bovine incisors were used to produce conical dentinal cavities (4.8 mm major x 2.8 mm minor diameter x 4 mm depth) and C factor of magnitude 3.1. These cavity preparations (n=28) were restored with composite resins Filtek One Bulk Fill (BF) (3M ESPE) or Zirconfill (ZF) (BM4) through the semi-direct technique using the Scotchbond universal adhesive system (3M ESPE) and cement dual resin Relyx Ultimate (3M ESPE). The B/T analysis was performed with the aid of a Vickers microhardness tester and the RU was performed using the push-out test in a universal testing machine. All samples were stored in distilled water at 37 °C for 24 hours or 6 months. The B/T and RU data were submitted to one- and two-way analysis of variance (ANOVA), respectively, with Tukey's post-test (p <0.05). Results: There was no statistically significant difference between the composite resins in B/T. For the RU, analyzing each aging time separately, the ZF composite resin showed higher values than the BF resin. However, analyzing over time, there was no statistically significant difference for any resin.