The importance of the palatoglossal airspace on the quality of digital panoramic radiographs

Abstract

Background Panoramic radiographs are a widely used fundamental diagnostic tool used by both general dental practitioners and specialist dentists. The quality of panoramic radiographs has often been compromised by patient position errors and the resultant, poor quality panoramic radiographs may cause mistakes in diagnosis. Pathology not seen may be missed or airspaces may be mistaken for pathology, resulting in unnecessary treatment and distress for the patient. The palatoglossal airspace is the most prevalent of the positioning errors and is the result of the patient not holding their tongue flat against the roof of the mouth. The traditional method of patient instruction ”hold your tongue to the roof of your mouth” depends on excellent patient communication skills to ensure the abscence of this airspace on panoramic radiographs. However, patients often do not understand where to place the tongue during the procedure, and are unable to consistently maintain the tongue pressed flat against the roof of the mouth. The resulting palatoglossal airspace in these radiographs appears as a dark, radiolucent band across the maxilla and the ramus of the mandible, and is known to hide or mimic pathology and compromise the quality of the radiographs. A new, simple breathing technique (SBT) of patient instruction was developed by the author to aid dental students when positioning patients for digital panoramic radiographs. Patients were simply told or shown how to ”breathe in, breathe out, swallow and hold still”. It was observed, that when students used the SBT to instruct patients, the correct position of the tongue was attained more often. Hence the SBT could be used with all patients, including young children, patients with special needs and patients from non-English speaking backgrounds. Aim The aim of this study was to determine the effect of the new SBT patient instruction method on the incidence and severity of the palatoglossal airspace (PGA) and the diagnostic quality of digital panoramic radiographs (DPR). Methods A retrospective, randomised selection, double-blinded study of matched digital panoramic radiographs was undertaken. One hundred sets of participant radiographs met the inclusion criteria of having one digital panoramic radiograph taken by dental students at Sydney Dental Hospital, using the new SBT patient instruction method and an earlier or later digital panoramic radiograph of those same patients, taken with the traditional method (TM) of instruction (in the period of 2010 to 2015). A new palatoglossal airway assessment score (PGAA) was developed and used in this study to both quantify and accurately describe this common airspace error. In addition the presence of other patient position errors and overall image quality were recorded. Statistical analysis of results was carried out using IBM Statistic Package for the Social Sciences (SPSS) version 20 software. Results The severity and incidence of the palatoglossal airspace (PGA) were significantly reduced by the student use of the new SBT method of patient instruction (p<0.003). The overall quality of digital panoramic radiographs (DPR) demonstrated that students using the SBT had less undiagnostic images and more clinically acceptable images than those taken using the traditional method. The participant population consisted of 39% males and 61% females. Ages ranged from four to 85 years, with a median age of 46 years. The population included 12% of children below 14 years, 15% of the participants had disabilities and 33% of the total population did not speak English at home. Conclusion The diagnostic quality of digital panoramic radiographs taken by students using the new SBT of patient instruction was improved, principally by the reduction of the palatoglossal (PGA) airspace. The decrease in both the incidence and severity of the most common patient positioning error, the PGA, will reduce the need for further radiographs and help to reduce missed and mistaken pathology in the maxilla and the ramus, thus improving overall health outcomes to the patient, reduce radiation dosage and yield economic benefits to the hospital or dentist. The new scoring system for the severity of the PGA will act as a criterion based guide for clinicians to assess the diagnostic quality of the radiographs, to be used in future research studies as a quantitative tool and may become a new gold standard for panoramic radiography quality assessment.