|dc.description.abstracteng||Aim: The aim of this in-vitro study was to analyse the bonding performances of self-adhesive flowable composites on enamel, dentin, and a nano-hybrid composite.
Material and methods: Three self-adhesive composites (Constic, DMG Germany; Fusio Liquid Dentin, Pentron Clinical USA; Vertise Flow, Kerr Dental Italy) were tested on enamel and dentin surfaces. As a reference the conventional composite Venus Diamond Flow (Heraeus Kulzer Germany) was used. The conventional composite was tested in combination with an adhesive (Optibond FL, Kerr Dental Italy) in etch&rinse technique. After thermal cycling (5000 cycles, 5-55°C) shear bond strength was measured and failure modes were assessed in all subgroups (each n = 16). To analyse repair bond strength, nano-hybrid composite specimens were prepared and aged by thermal cycling (5000 cycles, 5-55°C). The surfaces were treated with Al2O3 air abrasion, mechanical roughening, silica coating/silanization or were left untreated. Before the respective composites were applied, an adhesive (Optibond FL, Kerr Dental Italy) was applied in half of the groups. All nano-hybrid composite specimens then underwent a second thermal cycling procedure (5000 cycles, 5-55°C). Shear bond strengths and failure modes were analysed for all specimens (each subgroup n = 16). Statistical analysis was provided by ANOVAs/Bonferroni post hoc tests, Weibull statistics and χ 2-tests (p < 0.05).
Results: The self-adhesive composites reached significantly lower shear bond strengths on enamel (< 5 MPa) and dentin (< 3 MPa) than the conventional composite (enamel: 13.0 ± 5.1 MPa, dentin: 11.2 ± 6.3 MPa). Cohesive failures could only be observed in the reference group. Repair bond strengths were significantly related to the mechanical surface treatment (silica coating / silanization > mechanical roughening = Al2O3 air abrasion > no treatment). Repair bond strength of the conventional composite was increased by the application of Optibond FL, while the repair bond strengths of the self-adhesive composites were not improved by the application of the adhesive. The majority of cohesive failures occurred within the reference group.
Conclusion: Bonding of self-adhesive flowable composites to enamel and dentin is low, they cannot be recommended as direct filling materials. Repair bond strengths on nano-hybrid composite are significantly higher, self-adhesive flowable composites therefore show potential as repair materials for composite restorations as far as the repair surface is small and limited to the composite area.||de