This chapter describes periodontal-restorative interrelationship. It is a well-established fact that the periodontal health and the restoration of teeth share an intimate and inseparable interrelationship. For the periodontium to remain healthy, restorations must be critically prepared so that, they will remain in harmony with the surrounding periodontal tissues. This chapter covers the sequence of treatment, margins of the restorations, restorative margins encroaching on the biologic width, crown contour, hypersensitivity to dental materials, proximal contact and embrasure, pontic design. Restoration of contour plays an important role in the maintenance of periodontal health. An ideal contour must provide access for hygiene, fullness to create the desired gingival form, esthetically pleasing tooth contour, and protection of the marginal gingiva from mechanical injury during mastication.