Incorporation of inorganic fillers into experimental resin adhesives: Effects on physical properties and bond strength to dentin

• Published in: International journal of adhesion and adhesives Vol. 62; pp. 78 - 84
• Main Authors: Lúcia Rodrigues Macedo, Cármen, Aldrighi Münchow, Eliseu, da Silveira Lima, Giana, Henrique Zanchi, Cesar, Aulo Ogliari, Fabrício, Piva, Evandro
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2015
• Subjects: Adhesives; Bonding strength; Dentin; Durability; Fillers; Nanofillers; Physical properties; Polymers; Resins; Self-etch adhesive; Silicon dioxide; Ytterbium trifluoride; Durability; Ytterbium trifluoride; Nanofillers; Self-etch adhesive
• ISSN: 0143-7496; 1879-0127
• DOI: 10.1016/j.ijadhadh.2015.07.001

This study investigated the effect of different monomeric systems and inorganic fillers on the physical properties of experimental resin adhesives and on the immediate and 6-month bond strength to dentin. Two, 2-step self-etch adhesive systems were prepared: two primers (constituted of GDMA-P, ethanol, water, and HEMA or PEG(400)-UDMA) and two adhesives (constituted of Bis-GMA, TEGDMA, and HEMA or PEG(400)-UDMA). Next, the adhesives were allocated into three groups according to filler incorporated: unfilled (control), silica (SiO2), or ytterbium trifluoride (YbF3). Degree of conversion (DC, after 30 and 60s of light-activation), water sorption (WS) and solubility (SL), and flexural strength (σ) and modulus (Ef) tests were performed for all adhesives. A microtensile bond strength (µTBS) test to dentin was evaluated after 24h (immediate) and 6 months (6-month) of water storage using a universal testing machine (DL500, EMIC). Data were analyzed using statistical tests (α=5%). The adhesives showed similar DC at a same light exposure time, although light-activation for 60s improved conversion of monomers. The unfilled HEMA-containing adhesive showed higher WS, SL, σ and Ef compared to others. The incorporation of fillers into the adhesives did not affect negatively the immediate µTBS results; however, after 6 months the presence of SiO2 impaired in complete premature failures, and the presence of YbF3 reduced the µTBS in the PEG(400)-UDMA-based group. The unfilled HEMA-containing group also reduced bond strength after 6 months of water storage. In conclusion, depending on the resin matrix composition, YbF3 seems to be a good option for reinforcing adhesive systems.