Mandibular changes on panoramic imaging after head and neck radiotherapy.

OBJECTIVES: Changes to the radiographic appearance of the jaws after head and neck radiotherapy have not been thoroughly characterized. This retrospective study examines changes to the appearance of the mandible on panoramic images following intensity-modulated radiotherapy (IMRT) and relates these changes to medical co-morbidities and radiation dose. STUDY DESIGN: The medical and dental charts, and panoramic images of 126 patients who received IMRT at the Princess Margaret Hospital between January 1, 2005, and December 31, 2008, were analyzed independently by three observers. RESULTS: Of the 126 patients, 75 (60%) had post-IMRT changes, as seen on panoramic images; most, 66 (88%), consisted of widened periodontal ligament space (WPLS). The median time to WPLS was 29 months after IMRT. Female gender and radiation dose correlated with decreased time to WPLS. CONCLUSIONS: These results indicate that WPLS is a common radiographic sequela after head and neck radiotherapy, underscoring its clinical significance as a reliable marker of irradiated bone. Furthermore, this type of WPLS needs to be differentiated from odontogenic inflammatory disease and cancer recurrence to avoid unnecessary treatment that may precipitate osteoradionecrosis.

The effects of voxel size on cone beam computed tomography images of the temporomandibular joints.

OBJECTIVES: This clinical study assesses the effect of cone beam computed tomography (CBCT) voxel size on the ability to detect osseous changes associated with degenerative disease of the temporomandibular joint (TMJ). The effect of voxel size on perceived CBCT image quality is also evaluated. STUDY DESIGN: Twenty-two patients presenting for TMJ imaging with suspected degenerative disease were imaged with the Carestream 9000 CBCT unit, using separate right and left joint acquisitions (n = 44). Images were archived at native and downsampled voxel resolutions of 76 µm and 300 µm, respectively. Three oral and maxillofacial radiologists evaluated the images for osseous changes, as well as image quality by using a visual analog scale. RESULTS: There was no statistically significant difference between the voxel sizes in the detection of TMJ osteoarthritic changes. The mean visual analog scale response did, however, differ significantly between the two groups (P = .02). CONCLUSIONS: Despite no improvement in diagnostic efficacy with a smaller voxel size, perceived image quality is consistently higher for images with greater spatial resolution.

A retrospective analysis of referral patterns for oral radiologic consultation over 3 years in Ontario, Canada.

OBJECTIVES: To determine the types of practitioners who most commonly refer and the film type and diagnostic entities that are most frequently submitted for oral radiologic consultation in Ontario, Canada. STUDY DESIGN: A total of 430 referral letters and responses from 2 Ontario oral radiologists from 2003 to 2005 were analyzed. Data collected included the specialty of the referring practitioner, the film type(s) submitted, the radiographic density of the entity of interest, and the interpretation by the radiologist. RESULTS: General practitioners (58.9%) and oral surgeons (21.5%) were the most frequently referring practitioner types, representing 1.2% and 17.1% respectively of each group practicing in Ontario. Also, 18.2% of oral pathologists referred. Panoramic radiographs (79.5%) were included in referrals more often than intraoral radiographs (46.0%). Of the entities, 37.0% were radiopacities, 27.4% were radiolucencies, and 13.5% had mixed radiopaque-radiolucent density. The radiologists interpreted normal features (55.6%) most often. CONCLUSION: Panoramic radiographs with normal findings were submitted to oral radiologists for consultation most frequently in Ontario.

The role of basic sciences in diagnostic oral radiology.

Although it is generally taken for granted that dental education must include both basic science and feature-based knowledge components, little is known about their relative roles in visual interpretation of radiographs. The objectives of this study were twofold. First, we sought to compare the educational efficacy of three learning strategies in diagnostic radiology: one that used basic scientific (pathophysiologic) information, one that used feature lists structured with an organizational tool, and one that used unstructured feature lists. Our second objective was to determine whether basic scientific information provides conceptual coherence or is merely a simple means for organizing feature-based knowledge. Predoctoral dental and undergraduate dental hygiene students (n=96) were randomly assigned into three groups (basic science, structured algorithm, and feature list) and were taught four confusable intrabony entities. The students completed diagnostic and memory tests immediately after learning and one week later, and these data were subjected to a 3x2 repeated measures ANOVA. For the diagnostic test, students in the basic science group outperformed those assigned to the feature list and structured algorithm groups on immediate and delayed testing (p<0.05). A main effect of learning condition was found to be significant. On the memory test, performance was similar across all three groups, and no significant effects were found. The results of this study support the critical role of basic scientific knowledge in diagnostic radiology. This study also refutes the organized learning theory and provides support for the conceptual coherence theory as a possible explanation for the process by which basic science aids in diagnosis.

The evolution and application of dental maxillofacial imaging modalities.

During the last decades, an exciting new array of imaging modalities, such as digital imaging, CT, MRI, positron emission tomography, and cone-beam CT (CBCT), has provided astounding new images that continually contribute to the accuracy of diagnostic tasks of the maxillofacial region. The most recent, cone-beam imaging, is gaining rapid acceptance in dentistry because it provides cross-sectional imaging that is often a valuable supplement to intraoral and panoramic radiographs. The information content in such examinations is high and the dose and costs are low. The increasing trend toward the use of CBCT in dental offices may be expected to result in improved diagnosis, but with increased patient dose and health care costs. Using CBCT as a secondary imaging tool helps optimize health-to-risk ratio.