1680s, "pressed closely in," past-participle adjective from impact (v.). Of teeth from 1859.
Entries linking to impacted
impact v.
c. 1600, "press closely into something," from Latin impactus, past participle of impingere "to push into, drive into, strike against," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + pangere "to fix, fasten" (from PIE root *pag- "to fasten"). Original sense is preserved in impacted teeth. Sense of "strike forcefully against something" first recorded 1916. Figurative sense of "have a forceful effect on" is from 1935. Related: Impacting.