Sharon L. Brooks

Imaging of the temporomandibular joint: a position paper of the American Academy of Oral and Maxillofacial Radiology.

Various imaging techniques for the temporomandibular joint are discussed with respect to uses, strengths, and limitations. An imaging protocol is outlined for evaluating patients with a wide variety of temporomandibular joint related signs and symptoms.

Oral radiographs in the detection of early signs of osteoporosis

A study was conducted to determine whether radiographic changes could be detected in the mandible of patients with mild-to-moderate postmenopausal osteoporosis and whether these changes could be used as a diagnostic tool to differentiate normal from osteoporotic patients. Subjects were classified as either osteoporotic (21) or normal (14) on the basis of bone density measurements of the lumbar spine and femoral neck, as determined by dual-photon absorptiometry. Mandibular bone density measurements were made on panoramic and periapical radiographs and expressed in terms of millimeters of aluminum equivalent. Thickness of the cortex at the angle of the mandible, sinus floor, and lamina dura of the tooth socket was also measured. There were no significant differences in any of the mandibular measurements between the normal and osteoporotic subjects. Whereas the skeletal bone measurements were correlated with each other, there was no correlation between skeletal and mandibular bone measurements. Women with mild-to-moderate osteoporosis could not be distinguished from women with normal bone density with the method described in this article.

Accuracy of clinical diagnosis for TMJ internal derangement and arthrosis

This study investigated the accuracy of clinical examination in determining the status of the temporomandibular joint with respect to internal derangement and arthrosis. A series of 110 patients was given standard clinical examinations followed by bilateral imaging with arthrography and/or magnetic resonance imaging. There was agreement between the clinical diagnosis and the imaging finding in 95 joints (43%). In the other 125 joints (57%), the clinical diagnosis did not agree with imaging findings. There were false-positive clinical diagnoses in 39 joints and false-negative clinical diagnoses in 31 joints. In the other 55 joints the clinical diagnosis correctly indicated that the joint was abnormal but was incorrect about the stage of abnormality. On the basis of the overall diagnostic accuracy of 43%, it was concluded that a clinical examination is not reliable for determining the status of the joint in patients with signs and symptoms of temporomandibular joint internal derangement.

Prevalence of osseous changes in the temporomandibular joint of asymptomatic persons without internal derangement.

There is a controversy in the literature regarding the prevalence of osseous changes in the temporomandibular joint (TMJ) of asymptomatic persons. Using cephalometrically corrected tomograms, we assessed one TMJ of each of 34 asymptomatic persons who had no arthrographic or magnetic resonance imaging evidence of internal derangement. Minimal flattening of the condyle or articular eminence was seen in 12 joints (35%). More advanced osseous changes such as erosion, osteophytosis, or sclerosis were not seen in any joint. The findings suggest that generally no osseous changes occur in the TMJ in asymptomatic persons without internal derangement. When osseous changes occur, they are confined to minimal flattenings. Minimal flattening is probably of no clinical significance because the persons were asymptomatic, and arthrography and magnetic resonance imaging showed no evidence of abnormalities in the soft tissues.

Temporomandibular joint disk displacement without reduction. Treatment with flat occlusal splint versus no treatment.

A flat occlusal splint has been extensively used in the treatment of patients with temporomandibular joint disk displacement without reduction, but no studies with untreated controls have assessed its effect. We randomly assigned 51 patients with temporomandibular joint pain and arthrographically verified disk displacement without reduction to be treated with a flat occlusal splint or to serve as untreated control subjects in a 12-month clinical trial. Pain symptoms disappeared in about one third of the patients in each group. Another third of the patients in the control group improved. Sixteen percent of the patients in the control group and 40% of the patients treated with a flat occlusal splint were worse at the end than at the beginning of the study. Joint pain and muscle tenderness decreased more frequently in the nontreatment controls than in the treatment group. A statistically significant benefit of a flat occlusal splint over nontreatment control subjects could not be identified in this study of patients with painful disk displacement without reduction. The use of a flat occlusal splint in this patient group should therefore be reconsidered.

The appearance of mental foramina on panoramic radiographs. I. Evaluation of patients

The appearance of the mental foramen on panoramic radiographs can be classified as a continuous, separated, diffuse, or unidentified type. In a sample of 297 patients, the most frequent appearance was separated (43%), followed by diffuse (24%), continuous (21%), and unidentified (12%). There were no significant differences in foramen diameter or relative vertical position within foramen types or developmental stages of the dentition. It is strongly suspected that sometimes the radiographic landmark presumed to be the mental foramen may actually be the reappearance of the mental canal.

The appearance of mental foramina on panoramic and periapical radiographs. II. Experimental evaluation.

The image of the mental foramen was studied on panoramic and periapical radiographs taken on four dry skulls with a variety of vertical and horizontal angulations, skull positions, and exposure times. It was found that any change in exposure conditions affected both the type of appearance (continuous, separated, diffuse, or unidentified) and the relative vertical position of the foramen. The radiographic position agreed with the actual position less than half the time regardless of technique, although the apparent diameter of the foramen was close to the true diameter.

Evaluation of panoramic dental radiographs taken in private practice

Five hundred panoramic radiographs submitted to Delta Dental Plan of Michigan for preauthorization or claim processing were evaluated for frequency of occurrence of 15 categories of technical errors in patient positioning, film processing, and general film handling. Only one radiograph showed no errors. The average radiograph contained 2.2 positioning errors, 1.0 processing errors, and 1.5 miscellaneous errors, for a total of 4.7 errors. Of the 500 radiographs, 467 had positioning errors, 441 had processing errors, and 424 had miscellaneous errors. Diagnostic quality was judged to be adequate in 365 radiographs, inadequate in 91 radiographs and marginal in 44 radiographs. The severity of error was of more importance than the number of errors in the determination of diagnostic adequacy.

Compliance of Michigan dentists with radiographic safety recommendations

We surveyed a random sample of 398 Michigan dentists in private practice to determine their compliance with the American Dental Association Councils recommendations for radiographic equipment and techniques. The response rate was 67% of the questionnaires delivered successfully. The majority of dentists use only D-speed film (73%) and round collimation of the x-ray beam (90%). Only 5% have an x-ray machine equipped with a rectangular collimator and 18% have at least one machine with a pointed cone. Leaded apron use is almost universal, but only 49% of the dentists use cervical collars in addition to the apron. The majority of dentists surveyed do not comply with the American Dental Association Councils recommendations on film speed, collimation, and use of leaded cervical collar. Using effective dose equivalents determined by Gibbs et al. for a variety of radiographic techniques, we estimate that an eight-fold reduction in radiation dose could be achieved without eliminating a single radiograph if all dentists used E-speed film and collimation of the beam to the size of the film.

Temporomandibular joint: Surgically created disk displacement causes arthrosis in the rabbit☆

To document a causal relationship between temporomandibular joint disk displacement and arthrosis, the disk was surgically displaced in one temporomandibular joint in each of three rabbits. The rabbits were sacrificed after 4 weeks and the mandibular condyles were studied radiographically and histologically. All three joints that underwent disk displacement had radiographic and histologic evidence of arthrosis, which included erosion of the bone, irregularity and fissure formation of the articular soft tissue cover, disruption of the subchondral layer of cartilage cells, and chondrocyte proliferation. No radiographic or histologic changes occurred in the joints that were untouched. The results suggest that surgically created disk displacement can cause arthrosis in the temporomandibular joint of the rabbit.