THE INTERACTION OF ADHESIVE SYSTEMS WITH HUMAN DENTIN

Purpose: To investigate the interaction of six experimental and commer cial bonding systems with dentin in vivo. Materials and Methods: One-S tep, Clearfil Liner Bond 2, OptiBond, Permagen with 10% phosphoric aci d, Permagen with 35% phosphoric acid, and Prime & Bond were applied in standard Class I occlusal cavities in premolars scheduled for extract ion for orthodontic reasons, combined either with a self-cured or with a light-cured resin composite. The teeth were carefully extracted 5 m inutes after resin polymerization and fixed in 2.5% glutaraldehyde. Af ter fixation, the specimens were dehydrated, sectioned, and processed for field-emission SEM. Results: Although some systems produced gap-fr ee intact interfaces in specific specimens, all of them showed detachm ent at the transition between the resin-dentin interdiffusion zone and the fluid resin placed over it. It was apparent that the presence of air-bubbles and/or thick layers of polymerized-filled fluid resin resu lted in less frequent separation areas at the resin-dentin interface, providing support for the concept of the elastic cavity wall. It was a lso confirmed that some dentin adhesive systems do not form a thick la yer over the dentin, otherwise the resin composite would not have pene trated the dentin tubules.