INTERFACIAL ULTRASTRUCTURE OF THE RESIN-ENAMEL REGION OF 3 ADHESIVE SYSTEMS

Purpose: To observe the resin/enamel interface produced by different a dhesive systems. Materials and Methods: A conventional three-step smea r layer removing adhesive system (Scotchbond Multi-Purpose), a two-ste p smear layer removing adhesive system (Prime & Bond), and a two-step smear layer dissolving adhesive system containing a self-etching prime r (Panavia 21) were evaluated. Flat enamel surfaces were obtained from approximal surfaces of 18 extracted human molars. A total of 36 surfa ces were collected and divided into three groups of 12 samples. One-ha lf of each specimen in each group was etched with 35% phosphoric acid prior to the application of each adhesive system, with the second half being kept unetched. Subsequently, resin composite was placed and pol ymerized for 40 seconds. The samples were fractured and immersed into HCl and NaOCl solutions, followed by critical point drying and sputter coating for examination with a field emission scanning electron micro scope. Results: In the etched samples, Panavia 21 and Scotchbond Multi -Purpose showed more consistent resin tag penetration than did Prime & Bond. Unetched Prime & Bond and Scotchbond Multi-Purpose samples show ed minimal or no adhesive penetration in enamel surfaces.