The aim of the study is to present the influence of clinical activities in the production of prosthetic crowns on the condition of marginal periodontium. Positive and negative effects of crowns on the adjacent soft tissues and the alveolar bone have been presented. The article describes the anatomy of the marginal periodontium and its division according to the ratio of the crest to the dentogingival complex (DGK). The main focus was on the technical aspects of subgingival preparation which, if performed incorrectly, carries the risk of many complications, such as acute and chronic marginal gingivitis, recessions, periodontal pocket. Due to the high risk of iatrogenic damage to the biological width (BW) during preparation, appropriate procedures should be followed at every clinical and laboratory stage. It has been shown that by shaping the step during grinding, better depth control and better visibility of the preparation margin are achieved. The article draws attention to a very important aspect, which is a thorough analysis of the structure made at the laboratory stage. The analysis should include: assessment of the contour of the prosthetic crown, smoothness of the cervical surface, adhesion of the crown to the tooth stump, adaptation of the crown edges to the tooth grade, shape of the contacting walls of the crown, and their adherence to adjacent teeth.