The purpose of the present study was (1) to examine smear layer formation following different root planing modalities, and (2) to evalute its removal and the exposure of collagen using an ethylenediaminetetraacetic acid gel preparation. Twenty-four periodontitis-affected human teeth were mechanically root planed. Twelve teeth were etched with an ethylene-diaminetetraacetic acid gel preparation. The surfaces were examined by a scanning electron microscope. The results showed that root planing resulted in a smear layer covering the root surfaces, irrespective of treatment modality. The smear layer could be efficiently removed with the ethylene-diaminetetraacetic acid gel preparation. During this process, collagen fibers were exposed to varying degree