Effects of surface treatment on the free surface energy of dentin

Abstract Objectives . The purpose of this study was to evaluate the influence of six treatments on the dispersive, acid, and base components of the free surface energy of dentin. Methods . Occlusal dentin surfaces were polished with 4000 grit abrasive paper, washed and air dried. Characteristics of the surface energy were calculated by measuring contact angles of the four following liquids: α-bromonaphtalene, glycerol ethylene glycol, and water. The dentin was then treated with aqueous solutions containing: (1) oxalic acid and glycine (OX/GLY), (2) oxalic acid, glycine, and HEMA (OX/GLY/HEMA), (3) phosphoric acid (PA), (4) maleic acid (MA), (5) EDTYA, or (6) NaClO. After treatment, washing and air drying, the energy characteristics of the samples were evaluated again. Results . Three kinds of wetting behavior were observed: an increase (OX/GLY/HEMA), a stabilization (PA, NaClO) or a decrease (OX/GLY, MA, EDTA) of the wettability of the dentin surface. The calculations demonstrated that dentin surfaces are basic. Significance . This study of the evolution of the surface energy components gave information on adhesion mechanisms involving hydrophilic and hydrophobic interactions. The results may be helpful in the formulation of conditioners and primers.