Question

Difference between paralleling technique bisecting technique

Answer 1

Answer: in the explanation

Explanation:-

1)bisecting angle technique- The bisecting angle technique is an older method for periapical radiography. It can be a useful alternative technique when the ideal receptor placement using the paralleling technique cannot be achieved, for reasons such as anatomical obstacles e.g. tori, shallow palate, shallow floor of mouth, or narrow arch width.[16]

This technique is based on the principle of aiming the central ray of the X-ray beam at 900 to an imaginary line which bisects the angle formed by the long axis of the tooth and the plane of the receptor.[15] The image receptor is placed as close as possible to the tooth under investigation, without bending the packet. Applying the geometrical principle of similar triangles, the length of the tooth on the image will be the same as that of the actual length of the tooth in the mouth.[7]

The many inherent variables can inevitably result in image distortion and reproducible views are not possible with this technique.[17] An incorrect vertical tube head angulation will result in foreshortening or elongation of the image, while an incorrect horizontal tube head angulation will cause overlapping of the crowns and roots of teeth.[7]

Many frequent errors that arise from the bisecting angle technique include: improper film positioning, incorrect vertical angulation, cone-cutting, and incorrect horizontal angulation.[18]

2)paralleling technique-This can be used for both periapical and bitewing radiographs. The image receptor is placed in a holder and positioned parallel to the long axis of the tooth being imaged. The X-ray tube head is aimed at right angles, both vertically and horizontally, to both the tooth and the image receptor.

This technique is advantageous as the teeth are viewed exactly parallel with the central ray and therefore there are minimal levels of object distortion.[15] With the use of this technique, the positioning can be duplicated with the use of film holders. This makes the recreation of the image possible, which allows for future comparison.[7] There is some evidence that the use of the paralleling technique reduces the radiation hazard to the thyroid gland, as compared to the use of the bisecting angle technique