A survey of 3,874 routine full-mouth radiographs

A comprehensive study of 3,874 routine full-mouth radiographs yielded the following findings concerning retained roots and teeth: 1. The incidence of retained roots discovered in routine full-mouth radiographs of all types of patients was close to 20 per cent. Twice as many roots are retained in the maxilla as in the mandible, and over six times as many are retained in posterior areas as in anterior areas. 2. The incidence of retained roots in edentulous jaws was close to 24 per cent, and the incidence of retained and embedded teeth was 2.6 per cent. 3. The over-all incidence of radiolucencies associated with retained roots was over 50 per cent. 4. Of these retained roots, those exposed to the oral cavity were involved with radiolucent areas in 81 per cent of the cases, while roots lying beneath the surface or completely encased in bone had radiolucent areas around them in 20 per cent of the cases. 5. The size of the retained root had no influence on the incidence of associated radiolucent areas. 6. There was no difference in the numbers of radiolucencies between roots found in the maxilla and those found in the mandible, but a markedly higher incidence of involvement was noted in anterior areas as compared to posterior areas. 7. The incidence of retained roots of deciduous teeth which remain in the jaws is extremely small (1.2 per cent). 8. Retention of deciduous teeth occurred in one out of every sixty-three patients. The most frequently retained deciduous tooth was the maxillary cuspid. The significance of these findings is discussed, and the need for comprehensive radiographic examination of all patients is emphasized.