A smear layer is produced on the dentin surface after abrasion or cutting by instruments. Its removal is indicated or not according to the kind of bonding agent used in adhesive dentistry. The purpose of this study was to evaluate the possible effects of some substances on the smear layer. Twenty upper non-carious premolars, stored in isotonic saline solution, were mesiodistally hemi-sectioned and the buccal and lingual enamel was removed with high speed diamond bur. One millimeter of the dentinal surface was then removed with a water-cooled high speed carbide bur # 56 in order to obtain the smear layer. Different solutions were applied on the dentin surface for 30 seconds, which was then rinsed and dried. The specimens were mounted on metallic holder stubs, prepared, and examined under the scanning electron microscope (DSM 95-Zeiss). Removal of the smear layer by the tested solutions was qualitatively observed, and the solutions, rated according to their performance in increasing order of extent of removal, as follows: 1. air/water spray; 2. 2% NaF; 3. sodium hypochloride/anodic detergent; 4. 3% H2O2; 5. sandblasting with 50 <FONT FACE="Symbol">m</font>m aluminum oxide; 6. 1.27% acidulated fluoride; 7. 25% polyacrylic acid; 8. 10% phosphoric acid. The best solutions for the removal of the smear layer were the acid ones.
Smear layer; Dental cavity preparation; Dentin; Microscopy, electron, scanning
