RADIOGRAPHIC AMELOCEMENTAL JUNCTION AND ALVEOLAR CREST - EFFECT OF X-RAY-BEAM ANGULATION

The effect of X-ray beam angulation on the radiographic images of the amelocemental junction (ACJ) and alveolar crest (AC) and their positio ns relative to one another were assessed using a new laboratory model for radiographic studies. A total of 39 teeth with 62 usable approxima l surfaces were included in the investigation. When all tooth types we re combined, changes in vertical or horizontal angulation from baselin e through 20 degrees had no significant effect on the distance between the marked (true) ACJ and marked (true) AC. However, the distance bet ween the apparent (radiographic) ACJ and apparent (radiographic) AC wa s significantly reduced by varying the beam angulation in either a ver tical or horizontal direction. Results for individual tooth types were qualitatively similar but larger discrepancies were found in molars f ollowed by premolars and incisors. The results emphasize the importanc e of maintaining the ideal X-ray beam, tooth, bone, film relationship when taking radiographs for the assessment of periodontal destruction.