Browsing by Author "Pires, Paula Maciel"

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.

Minimally invasive (MI) concepts in restorative dentistry in the year 2020 request from the practitioner, not only a scientifically supported rational for carious tissue removal/excavation and defect-oriented, biological cavity preparation, but also a deep understanding of how to ensure a biomechanically stable and durable restoration in different clinical situations by applying different restorative options. Bio-reactive materials play an increasingly relevant role, as they not only replace diseased or lost tissue but also optimise tissue mineral recovery (among other properties) when used in restorative and preventive dentistry. Indeed, this is of certain interest in MI restorative dentistry, especially in those cases where gap formation jeopardises the integrity of the margins along resin composite restorations, causing penetration of bacteria and eventually promoting the formation of secondary caries. Recently, the interest on whether ion-releasing materials may reduce such biofilm penetration into margin gaps and reduce such a risk for development and propagation of secondary caries is growing significantly among clinicians and scientists. The aim of this article was to explore mechanisms involved in the process that allow mineral deposition at the interface between such materials and dentine and describe how conventional “bioactive” restorative materials currently available on the market may beneficial treatments in MI Dentistry.