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.