Accretion

(1) Increase by addition to the periphery of material of the same nature as that already present; e.g., the manner of growth of crystals. SYN: accrementition (2). (2) In dentistry, foreign material (usually plaque or calculus) collecting on the surface of a tooth or in a cavity. (3) A growing together. [L. accretio, fr. ad, to, + crescere, to grow]