Difference between Bisecting & Paralleling Techniques
Bisecting technique is when the image receptor cannot be placed parallel to the long axis of the tooth. It can be used without film holder when the anatomy of the patient precludes the use of a film-holding device. The Bisecting Angle Technique is an alternative to the paralleling technique for taking periapical films. The film can be held in the mouth with the bite block or a bisecting instrument may be used. An advantage would be that the Bisecting Technique is a lot more comfortable because the film is placed in the mouth at an angle to the long axis of the teeth. Therefore, the film doesn’t impinge on the tissues as much. Also there may be disadvantages along with the bisecting as in the film being less stable. Using finger retention, the film has more chance of moving during placement. Also, it is harder to position x-ray beam. As mentioned previously, because a film holder is often not used it is difficult to visualize where the x-ray beam should be directed. In the bisecting technique, the long axis of the tooth is not parallel with the long axis of the film. This results in a distortion of the image produced using this technique. In the left radiograph below, the buccal roots appear much shorter than the palatal root, even though in the actual tooth the lengths are not that much different. In the other radiograph taken with the paralleling technique, the lengths are projected in their proper relationship. Paralleling technique is the opposite technique from bisecting. The bisecting technique takes less time than paralleling technique does.
The paralleling technique results in good quality x-rays with a minimum of distortion and is the most reliable technique for taking periapical x-rays. The film is placed parallel to the long axis of the tooth in question ...