Shear bond strength of different surface treatments in bulk fill, microhybrid, and nanoparticle repair resins

Abstract

ObjectivesThe purpose of this study was to evaluate the influence of surface treatment and different types of composite resin on the microshear bond strength of repairs.Materials and methodsSeventy-two specimens (n=72) were prepared using a nanoparticle resin and stored in artificial saliva at 37 ± 1°C for 24 h. After this period, the specimens (n=24) were restored with microhybrid resin P60 (3M ESPE), nanoparticle resin Filtek Z350 (3M ESPE), and Bulk Fill Surefil SDR Flow (Dentsply) composite resins. Previously, the surfaces of the samples were treated, forming the following subgroups (n=12): (A) conditioned with 37% phosphoric acid for 30 s, and (B) abrasioned with a diamond tip for 3 s and conditioned with 37% phosphoric acid. In all groups, before insertion of the composite resin, the adhesive system Adper Single Bond 2 was actively applied and photopolymerized for 20 s.ResultsThe microshear test was executed to assess bond strength. Kruskal–Wallis (p<0.05) and Mann–Whitney statistical tests showed significant statistical difference considering that the bulk-fill resin turned out to have a lower bond strength than the conventional nanoparticle and microhybrid composites. With regard to the technique, the roughening with diamond bur followed by the application of phosphoric acid exhibited values higher than the exclusive use of acid.ConclusionThe microshear bond strength of the composite resin repairs varies in accordance with the type of composite resin utilized, and roughening the surface increased the bond strength of these materials.

Repair bond strength of bulk fill composites after different adhesion protocols

“…The specimens were aged for 30 days in artificial saliva at 37°C to simulate oral cavity conditions (10,11,15). Water absorption has a negative effect on composite restoration, causing a reduction in resistance to wear, residual monomers and hydrolytic degradation of chemical reactions (17).…”

“…Due to the reduced capacity to produce chemical reactions in repairs of aged restorations, it is necessary to perform a mechanical surface treatment to produce areas of macro- and micro-retention and increase the exposure of resin matrix and inorganic filler particles. In this research, a diamond bur was employed for roughening because it is a routinely used treatment in clinical practice, as well as its availability, technical simplicity and proven effectiveness in repair procedure research (7,10).…”

“…In an inverse simulation, a bulk fill composite showed significantly lower bond strength than conventional composites when used as repair material of nanoparticulate composite Filtek Z350 (10). In research involving only Z250, no significant differences were found between different adhesion protocols (14).…”

“…The two types of composites received mechanical treatment with a fine-grit diamond bur for three seconds, with the burs replaced by new ones after every five blocks treated (2,7,10).…”

“…Total replacement of restorations is a procedure that weakens the remaining structure, increases the risk of fracture and affects pulp vitality (7); researchers have also determined that restorations with localized defects that were previously repaired showed the same performance after ten years as restorations that had been completely replaced in marginal adaptation, secondary caries, anatomy and color (8). Thus, composite restorations can be considered the treatment of choice for small recurrent caries along the margin, partial staining and fractures (9,10).…”