(mar'jĭn )

[L. margo, border]

1. A border or boundary such as the edge of a structure, or of a pathological specimen removed from the body surgically.

   SEE: margo.

2. In dentistry, the apical extent or boundary of enamel adjacent to the cementum of the tooth root; the junction of a restoration with the cavosurface angle of a prepared cavity in enamel.

costal m.The lower (abdominal) border of the front of the rib cage formed by the costal cartilages of ribs 7 to 10. SYN: abdominothoracic arch; costal arch.

free gingival m.Gumline.

gingival m.Gumline.

m. of resection Surgical margin.

surgical m.The border of a tissue specimen that has been removed surgically from the body. It is often marked with an indelible dye to make it easily visible to the pathologist.

When obtaining biopsy specimens from a patient, the practitioner's goal is to obtain a tissue specimen that completely surrounds the lesion, so that the margins are free, i.e. not visibly penetrated by tumor cells.