EFFECTS OF SURFACE-TREATMENT ON THE FREE-SURFACE ENERGY OF DENTIN

Objectives. The purpose of this study was to evaluate the influence of six treatments on the dispersive, acid, and base components of the fr ee surface energy of dentin. Methods. Occlusal dentin surfaces were po lished with 4000 grit abrasive paper, washed and air dried. Characteri stics of the surface energy were calculated by measuring contact angle s of the four following liquids: alpha-bromonaphtalene, glycerol, ethy lene glycol, and water. The dentin was then treated with aqueous solut ions containing: (1) oxalic acid and glycine (OX/GLY), (2) oxalic acid , glycine, and HEMA (OX/GLY/HEMA), (3) phosphoric acid (PA), (4) malei c acid (MA), (5) EDTA, 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 demon strated that dentin surfaces are basic. Significance. This study of th e evolution of the surface energy components gave information on adhes ion mechanisms involving hydrophilic and hydrophobic interactions. The results may be helpful in the formulation of conditioners and primers .