(a) The soft tissue surrounding the TEETH. Also called the gingiva, this tissue protects underlying structures and helps to keep the teeth tightly in the jawbones. Inﬂammation of the gum is called gingivitis and may be due to dental PLAQUE or to systemic disorders such as LEUKAEMIA and SCURVY.
(b) A complex viscid substance which exudes from the stems and branches of various trees, and consists principally of arabin or bassorin. The two best-known gums are gum acacia and gum tragacanth. Gum-resins such as asafoetida, galbanum and myrrh also contain resin.