Effect Of Using Different Strips On Reducing The Most Common Error In Panoramic Imaging; Palatoglossal Air Space Shadow

Introduction Panoramic radiography is an extra-oral imaging technique and is considered an effective, fast, and relatively inexpensive diagnostic tool to examine dentofacial structures.Various errors such as open lips, shifted or tilted head position, inappropriate exposure parameters, movement of the patients, etc., have been reported for panoramic imaging, which reduce the quality of the images. The low quality of the radiographic images can result in misinterpretation by dentists, eventually leading to incorrect treatment plans. In addition, panoramic imaging errors ultimately can cause the repetition of radiography. In addition to wasting time and money, radiography repeating causes excess radiation exposure and increases the risk of potential damage in patients and medical radiation operators, including meningioma, brain tumors, and cancers, especially thyroid and Leukemia. Considering that the number of exposures to diagnostic radiation is relatively high during the lifetime, even a small increase related to the risk of cancer is of significant public importance.

Thus, numerous studies have highlighted the necessity of minimising medical and dental diagnostic radiation exposure as much as possible. Patient positional errors have been identified as the most frequent panoramic imaging errors, with some studies suggesting this is the case for nearly 95 percent of reported errors. Positional error and patient movement are two common reasons to reject dental imaging including intra-oral, extra-oral, and Cone-Beam Computed Tomography (CBCT). Thus, it is suggested that all dental radiography staff receive regular training focused on correct positioning techniques and reduction of patient movement.

The typical patient positioning errors in panoramic radiography include failure to rest the tongue against the palate, head positioned forward, head positioned backward, head twisted towards the left or right, head tilted to the left or right, the chin too high, the chin too low, a slumped position and inadequate neck extension, not resting the chin on the chin support, failing to use the bite guide, lips opened, patient movement during imaging and not removing the metal objects or prostheses. Among all the positional errors mentioned above, the most common error is the failure to keep the tongue against the palate.

Due to the failure of holding the tongue against the palate, the palatoglossal airspace (PGA) appears in panoramic radiographs as a dark radiolucent band under the hard palate and on the apices of the anterior maxillary teeth. This artefact significantly reduces the quality of the panoramic radiograph as it may be difficult or impossible to interpret the desired periapical region for correct diagnosis and treatment planning (for example, making it difficult to interpret cystic lesions in the anterior area of the upper jaw). In addition, when PGA falls on the ramus of the mandible, it may be mistaken for a fracture.

PGA may be seen unilaterally and asymmetrically as a localised radiolucent area if the patient swallows during panoramic imaging and momentarily does not touch the roof of the mouth. If the patient places only the tongue tip behind the maxillary teeth, a larger airspace is formed between the tongue and the hard palate.