Knowledge of the periodontal-restorative interface is critical in the fabrication of restorations that are functional and esthetic. Understanding biological principles allows the clinician to predict how the periodontium will respond to restorative therapy. Factors that influence the response to therapy in the periodontal-restorative interface are periodontal biotype, gingival architecture, alveolar crest position, gingival margin position, and gingival zenith.