Midsagittal plane positioning error will occur if the patient’s head is shifted to the left or right side. However, if the anterior teeth are positioned posterior to the focal trough, they will be magnified and the occlusal plane will appear flattened (Fig. If teeth are positioned anterior to the focal trough, the occlusal plane will be increased, a generalized increase of overlap of tooth contacts occurs, and the anterior dentition will be demagnified (Fig. The cost of a panoramic machine is approximately two to four times that of an intraoral x-ray machine.ĬOMMON ERRORS DURING PANORAMIC RADIOGRAPHYĪnterior teeth positioned outside the focal trough will result in blurring of the anterior teeth. Objects situated outside the focal trough will be distorted or obscured on the radiograph. Magnification, geometric distortion, and overlapped images of teeth sometimes occur. Panoramic radiography is an extraoral technique and the resultant image does not resolve the fine anatomic detail that may be seen on intraoral periapical radiographs. The disadvantages of panoramic radiographs relate to these weaknesses: Greater ease and less time necessary to produce a single image representing the patient’s entire dentition. One panoramic film generally delivers a radiation dose equivalent to about one set of four bitewing intraoral films. The broad anatomic region imaged, including additional visualization of the areas of the body of the mandible beyond the periapical region, the ramus, the temporomandibular joint, the maxillary sinus and the stylohyoid complex. Panoramic radiography offers several advantages over conventional intraoral radiography. Since each panoramic machine is slightly different, the manufacturer’s instructions should be followed carefully. Patients must be properly prepared and positioned with their head carefully aligned in the focal trough. Patient positioning is important for obtaining a detailed panoramic radiograph. The size and shape of the focal trough varies between manufacturers. Structures, which fall in front of or behind, the focal trough, can be distorted, magnified or reduced. The focal trough is the area in which structures will appear most sharply and clearly. The panoramic radiograph is composed largely of the anatomic structures located within this focal trough. The three-dimensional, horseshoe-shaped zone where images are sharp is called the focal trough, or image layer. These two components rotate simultaneously around the patient to produce an image. In panoramic radiography, the x-ray source and the film are connected to each other. Today, there are several types of panoramic machines available. Sometimes, however, the film is incorrectly referred to as a “Panorex”, which is the brand name of the panoramic x-ray machine first introduced to North America by the S.S. This film is referred to as a pantomograph or a panoramic radiograph. A panoramic radiograph can provide a view of the maxilla, mandible, temporomandibular joints, teeth and their supporting structures on one film (Fig.
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