Periodontal plastic surgery may be indicated to re-establish smile harmony. The aim of this case report is to emphasize the importance of the diagnostic wax-up in the fabrication of a periodontal surgical guide to achieve success in esthetic surgery. In the case presented, during the preoperative testing of the guide, it was verified that the laboratory planning was incompatible with the patient's biological measures. Therefore, had crown lengthening been performed based solely on the guide, it would have caused irreparable sequelae, such as the removal of keratinized tissue and root exposure, which, in turn, could result in esthetic and functional consequences. In this case report, the periodontal surgical guide that was based on the previous diagnostic wax-up was an instrumental component in accomplishing an esthetic surgical outcome.