Dental Assistant Practice Exam

Which of the following is a common radiographic error when using the bisecting angle technique?

1. Overexposure of the image

2. Elongation of the image

3. Penumbra effect

4. Foreshortening of the image

The correct answer is: Foreshortening of the image

The bisecting angle technique in dental radiography often leads to specific types of errors based on the positioning of the film or sensor relative to the tooth. Foreshortening of the image occurs when the angle of the X-ray beam is too steep in relation to the long axis of the tooth. This results in the tooth appearing shorter than its actual length on the radiograph. In the bisecting angle technique, the film or sensor is placed against the tooth while an imaginary line is drawn between the plane of the film and the long axis of the tooth. The X-ray beam is directed perpendicular to this bisecting line. If the X-ray beam is angled too steeply, it can lead to this foreshortening effect, distorting the image of the tooth. Understanding this error is crucial for dental assistants, as it emphasizes the importance of correct angulation and positioning in obtaining accurate radiographs, which are essential for diagnosis and treatment planning. Awareness of the potential for foreshortening helps to improve technique and minimizes the need for retakes, enhancing overall efficiency in a dental practice.