Do you know ghouls from goblins and ghosts?
1848, literally "around the tooth," from peri- + Greek odon (genitive odontos) "tooth" (see tooth).
periodontal per·i·o·don·tal (pěr'ē-ə-dŏn'tl)adj.
Surrounding or encasing a tooth.
Relating to or affecting tissues and structures surrounding and supporting the teeth.