An in-vitro study investigating the effect of air-abrasion bioactive glasses on dental adhesion, cytotoxicity and odontogenic gene expression

Abstract

Objective. To assess the microtensile bond strength (MTBS) and interfacial characteristics ofuniversal adhesives applied on dentine air-abraded using different powders. The analysisincludes the cytotoxicity of the powders and their effect on odontogenic gene expression.Methods. Sound human dentine specimens were air-abraded using bioglass 45S5 (BAG), poly-carboxylated zinc-doped bioglass (SEL), alumina (AL) and submitted to SEM analysis. Resincomposite was bonded to air-abraded or smear layer-covered dentine (SML) using an exper-imental (EXP) or a commercial adhesive (ABU) in etch&rinse (ER) or self-etch (SE) modes.Specimens were stored in artificial saliva (AS) and subjected to MTBS testing after 24 h and 10months. Interfacial nanoleakage assessment was accomplished using confocal microscopy.The cytotoxicity of the powders was assessed, also the total RNA was extracted and theexpression of odontogenic genes was evaluated through RT-PCR.Results. After prolonged AS storage, specimens in the control (SML) and AL groups showeda significant drop in MTBS (p > 0.05), with degradation evident within the bonding inter-face. Specimens in BAG or SEL air-abraded dentine groups showed no significant difference,with resin-dentine interfaces devoid of important degradation. The metabolic activity ofpulp stem cells was not affected by the tested powders. SEL and BAG had no effect on theexpression of odontoblast differentiation markers. However, AL particles interfered with theexpression of the odontogenic markers.