AbstractThe purpose of the present study was to compare cementum surfaces after etching at neutral or low pH in both healthy monkey teeth and periodontitis‐affected human teeth. 16 monkey teeth and 16 human periodontitis‐affected teeth were used. Etching with phosphoric and citric acids as well as EDTA was performed on the following surfaces: healthy monkey cementum, human cementum surfaces coronal and apical to the level of periodontal breakdown as well as exposed human dentin surfaces. Results indicate a profoundly higher capacity of EDTA to selectively expose collagen fibers in both healthy cementum surfaces and periodontitis‐affected dentin surfaces compared to agents operating at low pH which seemed to erode the surfaces to varying degrees. Variable results were seen on cementum surfaces which had been exposed to the environment of the periodontal pocket or the oral cavity. In view of this, it would seem preferable to mechanically remove the superficial layer of “diseased” cementum prior to the etching procedure. In conventional periodontal surgery, etching may be of limited value. However, in regenerative procedures, exposure of an intact collagenous matrix provides a matrix for retention of implants of biologically active substances such as growth factors, in addition to serving as a biocompatible surface for periodontal ligament cell col