The outside of a material or body. The fitting surface is that part of a restoration, prosthetic, or orthodontic appliance in contact with the supporting tissues. A smooth surface is a surface of a tooth on which pits and fissures are normally absent. A surface marker is a form of patient identification applied to the external surface of a denture; it may be either permanent or temporary (for identification during construction). Tooth surfaces are defined by their relationship to other anatomical structures.