The retained tooth root.
D000328:Adult; D000368:Aged; D006801:Humans; D008875:Middle Aged; D011859:Radiography; D012391:Root Resorption; D014081:Tooth Extraction / Q000009:adverse effects*; D014082:Tooth Fractures / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology / Q000601:surgery; D014092:Tooth Root / Q000000981:diagnostic imaging / Q000293:injuries*