Effect of nanostructured zirconium dioxide incorporation in an experimental adhesive resin

Abstract

Objectives

The aim of this study was to evaluate the influence of nanostructured zirconium dioxide incorporation in an experimental adhesive resin.

Methods

ZrO₂ particles were characterized by X-ray diffraction (XRD), micro-Raman spectroscopy and Brunauer–Emmett–Teller (B.E.T). Experimental adhesive resins were formulated with 0, 0.5, 1, 4.8, and 9.1% ZrO₂ in weight. The adhesives were evaluated based on degree of conversion (DC), radiopacity, softening in solvent and microtensile bond strength (μTBS) 24 h and after 1 year of aging. Mineral deposition at the hybrid layer was assessed with micro-Raman spectroscopy at the baseline and after 14 days.

Results

XRD showed monoclinic and tetragonal phases of ZrO_2.particles. B.E.T data revealed a surface area of 37.41 m²/g, and typical chemical groups were shown on the Raman spectra_. The addition of ZrO₂ did not influence the radiopacity. The addition of 4.8% and 9.1 wt.% ZrO₂ showed higher initial hardness with increased softening in solvent (P < 0.05) and promoted mineral deposition at the dentin interface. DC was significantly increased in the group with 1% ZrO₂ (P < 0.05). The μTBS test showed difference on the group with 9.1 wt.% of ZrO₂, with a significant reduction after aging.

Conclusion

The incorporation of ZrO₂ promoted mineral deposition on the adhesive interface and the addition of 1 wt.% caused a significant increase on the DC without compromising the other physicochemical characteristics, which may prove promising for the development of new dental adhesive systems.

Clinical relevance

The mineral deposition on the hybrid layer can result in a longer stability of the adhesive, thus delaying the hydrolytic degradation.

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