Load cycling enhances bioactivity at the resin–dentin interface

ObjectivesThe purpose of this study was to evaluate if mechanical loading promotes bioactivity at the resin interface after bonding with three different adhesive approaches.MethodsDentin 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 3 w. 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.ResultsLoading cycling for 3 w 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.SignificanceIn vitro mechanical loading promoted mineralization in the resin–dentin interfaces, at 24 h and 3 w of storage.

Graphical abstractMineral/Matrix ratio (MMR) calculated at the different Raman spectra after principal components analysis. ADH: adhesive; HL: hybrid layer; BHL: bottom hybrid layer; DEN: dentine; PA: phosphoric acid; SB: single-bond; EDTA: ethylenediaminetetraacetic acid; SEB: Clearfil SE bond; ctr: control; CL: cycling.Figure optionsDownload full-size imageDownload high-quality image (164 K)Download as PowerPoint slide