Influence of projection angles upon position of cementoenamel junction on radiographs

Abstract — The CEJ on radiographs is often used as a reference point in the assessment of alveolar bone loss. The aim of the present study was to test the stability of the radiographic CEJ ("RCEJ") in relation to the alveolar west under varying angulations of the central X-ray beam. In an experimental model four types of extracted teeth were radicrgraphed al 0° and 20° vertical angulation and at 15 horizontal angulations varying from a 17.5° mesial view to a 17.5° distal view. The buccal alveolar bone margin was simulated by a steel needle. RCEJ-"crest" distances were read at a × 10 magnification. Changing the vertical angutation from 0° to 20° reduced the RCEJ-"crest" distances far all tooth types (range ofaverage reduction 2.2–4.1 mm). HorizontaE angulations without concomitant vertical angularion had a significant effect but where without clinical significance. Horizontal anglslations in combination with a 20° vertical angulation bad a considerable influence; in a mesial view, mesial RCEJ-"crest" distances decreas-ed and distal ones increased, and vice wna in a distal view. The deviations from the true CEJ-crest distance demonstrated may be of clinical significance, and a critical attitude to alveolar bone loss measures on radiographs using the RCEJ as reference point is recommended.