Load cycling enhances bioactivity at the resin–dentin interface

Objectives The purpose of this study was to evaluate if mechanical loading promotes bioactivity at the resin interface after bonding with three different adhesive approaches. Methods Dentin surfaces were subjected to three different treatments: demineralisation by (1) 37% phosphoric acid (PA) followed by application of an etch-and-rinse dentin adhesive Single Bond (SB) (PA+SB), (2) by 0.5 M ethylenediaminetetraacetic acid (EDTA) followed by SB (EDTA+SB), (3) application of a self-etch dentin adhesive: Clearfil SE Bond (SEB). Bonded interfaces were stored in simulated body fluid during 24 h or 3w. One half of each tooth was submitted to mechanical loading. Remineralisation of the bonded interfaces was assessed by AFM imaging/nano-indentation, Raman spectroscopy/cluster analysis, dye assisted confocal microscopy evaluation (CLSM) and Masson's trichrome staining. Results Loading cycling for 3w promoted an increase of mechanical properties at the resin-dentin interface. Cluster analysis demonstrated an augmentation of the mineral-matrix ratio in SB-loaded specimens. CLSM showed an absent micropermeability and nanoleakage after loading EDTA+SB and SEB specimens. Trichrome staining reflected a narrow demineralised dentin matrix after loading, almost not observable in EDTA+SB and SEB. Significance In vitro mechanical loading promoted mineralization in the resin-dentin interfaces, at 24 h and 3w of storage.