1. A metal (usually gold) cast restoration of the occlusal surface of a posterior tooth or the lingual surface of an anterior tooth, the entire surface of which is in dentin without side walls; retention in the anterior tooth is by pins and in the posterior by pins and/or boxes in retentive grooves in the buccal and lingual walls. 2. A graft applied on the exterior of a bone. 3. A graft applied to skin in native urethra in hypospadias or stricture repair.
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on·lay 'ȯn-.lā, 'än- n
1) a metal covering attached to a tooth to restore one or more of its surfaces
2) a graft applied to the surface of a tissue (as bone)
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on·lay (onґla″) 1. a graft applied or laid on the surface of an organ or structure. 2. a cast metal restoration that overlays cusps, thus lending strength to the restored tooth.Medical dictionary. 2011.