In vitro mechanical stimulation promoted remineralization at the resin/dentin interface

Abstract

IntroductionTeeth are continuously subjected to mechanical loading during mastication, swallowing and parafunctional habits. The purpose of this study was to evaluate if mechanical loading is able to promote remineralization at etched and bonded dentin interfaces. MethodsFlat mid-coronal human dentin surfaces were subjected to different treatments: (1) demineralization by 37% phosphoric acid (PA) followed by application of an etch-and-rinse dentin adhesive: Adper™ Single Bond (SB) (PA+SB) or (2) treatment by 0.5M ethylenediaminetetraacetic acid (EDTA) followed by SB (EDTA+SB); (3) application of an self-etch dentin adhesive: Clearfil SE Bond (SEB). Restorations were accomplished, incrementally, with resin composite. In half of the specimens, mechanical loading (100,000 cycles, 3Hz, 49N) was applied. AFM imaging/nano-indentation, Raman spectroscopy/cluster analysis and dye assisted confocal microscopy evaluation (CLSM), were employed to detect remineralization at the interfaces. ResultsIn general, load cycling increased mechanical properties at the resin–dentin interface. Cluster analysis demonstrated a regular increase of the mineral-matrix ratio in EDTA+SB and SEB loaded specimens. CLSM showed a reduced micropermeability and nanoleakage after loading in bonded interfaces, and a most pronounced reduction in SEB samples. InterpretationIn vitro load cycling promoted remineralization at resin–dentin interfaces. Mineral content increased and nanomechanical properties were improved at both the hybrid layer and bottom of the hybrid layer. Higher mineral concentration in correspondence with a lesser concentration of demineralized dentin was observed, after loading.