Influence of X-ray beam angulation upon the radiographic image of proximal carious lesions

Twenty-two extracted human molars and premolars with a total of 34 initial proximal carious lesions were radiographed in 16 different views varying the horizontal angulation of the X-ray beam in steps of 2.5 degrees. The radiographs were read simultaneously by three observers. Clinical and radiographic diagnoses were compared. When utilizing all 16 views the concordance was 95%. All proximal surfaces were scored using four scoring classes. Surfaces without radiolucencies were scored 0, and carious surfaces were scored according to the extent of the radiolucencies. Nine sound and 12 carious surfaces were assigned identical scores in all 16 views, while 22 (65%) of the carious surfaces were assigned two, three or four different scores. Deviations from a direction of the X-ray beam tangential to the proximal surface eliciting a radiographic image belonging to a different score were measured. In 71% of the cases a deviation of 7.5 degrees or less elicited a different score. Projectional circumstances should be taken into consideration in interpreting proximal radiolucencies.