Use of the adhesive layer as a controlled release platform for doxycycline, as promising advancement for longer durability of dentin adhesion

Abstract

Abstract The loss of dentin adhesive efficiency can put at risk the durability of dental restorations. This loss of stability is a result of the combination of hydrolysis and the activity of metalloproteinases. The use of enzyme inhibitors can obtain higher adhesive stabilities. In this sense, the present paper aimed to evaluate the efficiency of doxycycline releasing adhesive systems using clay particles as a release modulator. The adhesive systems were based on BisGMA, UDMA, HEMA, and TEGDMA, including camphorquinone (photoinitiator) and ethanol (solvent). Different amounts of doxycycline (1–4%) were added to these systems in the presence or absence of 0.2% clay. The systems were evaluated by X-ray diffraction, infrared spectroscopy, flexural strength (and elastic modulus), doxycycline release, dentin MMP-2 inhibition capacity, and dentin adhesion. The results indicated that the addition of clays reinforces the adhesive systems mechanically, generating greater adhesive strengths. These nanoparticles also contribute to obtaining more controlled release profiles allowing a longer effective period of MMP-2 inhibition. The use of 1 and 2% of doxycycline, when combined with the clays, was able to elevate the adhesive stability after 18 months, indicating that clays in these systems represent a highly promising alternative to increasing the stability of dentin adhesion.