All prosthetic and restorative therapies require a healthy periodontium as a prerequisite for success. Understanding of the concepts of periodontal-restrorative interaction, especially with regard to interactions at the gingival margin is important. The aim of this article gives the information about the essential considering factor for successful prosthesis; biologic width, periodontal biotype, width of attached gingiva, margin of restoration. If a restorative margin must be extended below the gingival margin, it is critical that adequate band of attached gingiva is present, the margin does not violate the biologic width, the margin is closed and properly finished.