This study compared the surface characteristics of periodontally diseased single human teeth extracted after treatment with either EDTA or Tetracycline Hcl. The study was comprised of 30 teeth from 20 patients with advanced periodontal disease. Diseased root surfaces were root planed by hand curette or finishing bur. The teeth were sectioned and solutions of EDTA (pH 7.3) or Tetracycline Hcl (pH 1.8) were applied to the surface with cotton pellets for 3 minutes using light pressure. Specimens were processed and examined by Scanning Electron Microscope. The surfaces of both etched treated sets of specimens differed considerably from specimens treated with root planing alone, regardless of the root planing method. The etched specimens exhibited numerous dentinal tubules exposed by the removal of smear layer.