Influence of polar solvents on permeability, stiffness and collagen dissociation of demineralized dentin

Abstract

The purpose of this in vitro study was to evaluate and compare the effect of dimethyl sulfoxide (DMSO) or ethanol on the permeability, stiffness and collagen dissociation of demineralized dentin.Dentin cubes (2 × 2 × 2 mm) were demineralized in EDTA and incubated in DMSO or ethanol (0.01, 0.1, 1, 5, 10, 20, 50 and 100%) (n= 10/group) for 30 s, followed by 100% HEMA incubation. Extracted HEMA was quantified. For elastic modulus (E), demineralized dentin beams (6 × 2 × 1 mm) were incubated in DMSO or ethanol (1, 10, 20, 50 and 100%) for 10, 30 or 60 min at 3-point bending. Additional demineralized dentin discs (1 mm) were incubated in DMSO (1, 10, 50 and 100%) for 10, 30 and 60 min and the optical clearing effect was observed. The data were analyzed using ANOVA and Tukey's test (α=0.05) using SigmaPlot (Systat Software Inc., San Jose, CA).Compared to controls, HEMA uptake was significantly higher with all DMSO concentrations, and with 0.1% or higher ethanol concentrations (p<0.05). HEMA uptake in DMSO-incubated specimens (0.01, 5 and 10%) was significantly higher than with the ethanol incubation. Significant increase in elastic moduli was observed with 50–100% DMSO- and only with 100% ethanol after 10 min incubation. The optical clearing effect of 50–100% DMSO-incubated dentin disks was observed starting from 10 min.The pretreatment of dentin surfaces with low concentrations of DMSO resulted in significant improvement of the penetration of monomers to demineralized dentin matrices. Increase in penetration of monomers combined with a reversible stiffening of dentin collagenous matrix may explain the previously shown increase in durability of wet- or dry-bonded adhesive interfaces with DMSO treatment.