Stuart C. White

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.

Alterations of the trabecular pattern of the jaws in patients with osteoporosis

OBJECTIVE The purpose of this study was to determine whether the morphologic features of the trabecular bones of the maxilla and mandible differ between patients with osteoporosis and normal controls. STUDY DESIGN Periapical radiographs, obtained from dentists of 11 patients with osteoporosis and 12 control subjects, were digitized at 600 dpi. A custom computer program measured morphologic features of the trabecular architecture. The mean values for each feature were determined for the osteoporotic and control groups and compared by anatomic site. RESULTS Twenty-four morphologic features of the trabeculae and marrow regions were examined in each anatomical site. A principal components analysis summarized these predictors to four. The Hotelling T (2) test found that patients with osteoporosis had significantly altered morphologic pattern in the anterior maxilla (P =.019) and the posterior mandible (P =.013) in comparison with the controls. A classification tree analysis separated all subjects into 2 groups with 92% accuracy. CONCLUSIONS The data support the hypothesis that patients with osteoporosis have an altered trabecular pattern in the jaws in comparison with normal subjects.

Clinical and panoramic predictors of femur bone mineral density

Dentists are a potentially valuable resource for initial patient screening for signs of osteoporosis, as individuals with osteoporosis have altered architecture of the inferior border of the mandible as seen on panoramic radiographs. Our aim was to evaluate the efficacy of combining clinical and dental panoramic radiographic risk factors for identifying individuals with low femoral bone mass. Bone mineral density was measured at the femoral neck and classified as normal, osteopenic or osteoporotic using WHO criteria in 227 Japanese postmenopausal women (33–84 years). Panoramic radiographs were made of all subjects. Mandibular cortical shape and width was determined and trabecular features were measured in each ramus. Mean subject age, height, and weight were significantly different in the three bone-density groups (P<0.0001). A classification and regression trees (CART) analysis using just clinical risk factors identified 136 (87%) of the 157 individuals with femoral osteopenia or osteoporosis. Mean mandible cortical width (P<0.0001), cortical index (P<0.0001) and trabecular features (P=0.02) were also significantly different in the three bone density groups. A CART analysis considering only radiographic features found 130 (83%) of the 157 individuals with femoral osteopenia or osteoporosis, although none of the subjects with osteoporosis was correctly identified. A CART analysis using both clinical and radiographic features found that the most useful risk factors were thickness of inferior border of the mandible and age. This algorithm identified 130 (83%) of the 157 individuals with femoral osteopenia or osteoporosis. The results of this study suggest that 1) clinical information is as useful as panoramic radiographic information for identifying subjects having low bone mass, and 2) dentists have sufficient clinical and radiographic information to play a useful role in screening for individuals with osteoporosis.

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.

Film-holding instruments for intraoral subtraction radiography

Clinical application of digital subtraction radiography is limited by the reproducibility in the orientation of the x-ray source, image receptor, and object. In this study, eight dental intraoral film alignment instruments (including five replicates of each) were tested for accuracy in repositioning over a period of 6 months. Each instrument was made by adhering one of six impression materials (including acrylics, compounds, and elastics) onto the bite blocks of commercially available alignment instruments. The dimensional accuracy and reproducibility of the orientation of the x-ray source with respect to the object were determined over time for each instrument by measuring the horizontal and vertical angulation change in the position of a buccally placed marker on a dried mandible with a lingually placed film grid. Nine measurements were made during the 6-month test period. The most reproducible instrument was the combination of Regisil, an elastic impression material, and a Rinn XCP bite block. This combination yielded a mean absolute horizontal angulation error of 1.34 degrees +/- 0.63 and a mean absolute vertical angulation error of 2.04 degrees +/- 0.82, yielding a total angulation error of 2.44 degrees +/- 1.16. This was within the acceptable range of accuracy needed to produce diagnostically useful information when digital subtraction radiography is used.

Dentition, Dental Health Habits, and Dementia: The Leisure World Cohort Study

To explore the association between dentition and dental health behaviors and incident dementia.

Risk factors for fractures in older men and women: The Leisure World Cohort Study.

BACKGROUND Osteoporosis results in >1.5 million fractures in the United States each year, leading to substantial health care costs and loss of quality of life. One major gap in our knowledge is how to effectively identify individuals at risk of developing a fracture. OBJECTIVE We examined a population-based cohort for risk factors for fractures of the hip, wrist, and spine in men and women. METHODS The Leisure World Cohort Study was established between 1981 and 1985 when residents of a southern California retirement community completed a postal health survey. Multiple lifestyle, medical, attitudinal, and anthropomorphic factors were self-reported. Fractures were identified from 4 follow-up surveys, hospital discharge records, and death certificates. Fracture rates were determined separately for men and women. Cox proportional hazards regression was used to identify predictors of fracture. RESULTS Incident fractures of the hip (n = 1,227), wrist (n = 445), and spine (n = 729) incurred over the course of 2 decades were identified in the 13,978 residents surveyed. Mean (SD) age at entry was 74.9 (7.2) years for men and 73.7 (7.4) years for women. The most important risk factors for fracture were the same in men and women: age increased risk of hip and spine fractures (hazard ratio [HR] = 2.3-3.2 per 10 years) and history of fracture increased fracture risk at all 3 sites (HR = 1.4-3.2). In both men and women, glaucoma was a significant risk factor for hip fracture (HR = 1.9 and 1.3, respectively), and smoking was a risk factor for hip and spine fractures. Men and women with a positive mental attitude had fewer hip and spine fractures (HR = 0.7-0.9). High body mass index was protective at all 3 fracture sites in women (HR = 0.7-0.8), but those who used vitamin A supplements had increased rates of hip and wrist fracture (HR = 1.1 per 10,000 IU per day). CONCLUSIONS Attitude, lifestyle choices, and the presence of medical conditions may influence the rate of osteoporotic fracture in older women and men and may help identify individuals at high risk.

Xeroradiography for intraoral dental radiology: A process description

A novel x-ray imaging system for intraoral dental radiography is described. The imaging process is based on xeroradiographic principles. The surface of a small selenium photoreceptor is electrically charged. After insertion into a light-tight cassette, the photoreceptor is placed intraorally and x-ray exposed like film. The resultant electrostatic charge image is developed in a processor using liquid toner. The toner image is then transferred from the photoreceptor and fixed to a white plastic substrate for viewing. After cleaning, the photoreceptor is available for reuse. In contrast to film images, xeroradiographic images are exposed and processed sequentially. Processing time is approximately 20 seconds. Two image characteristics--edge enhancement and deletion--are primarily responsible for many advantageous qualities of xeroradiographic images over film images. An experimental processor was tested successfully at two dental schools.

Impact of cone-beam computed tomography on orthodontic diagnosis and treatment planning.

INTRODUCTION In this study, we measured the impact of cone-beam computed tomography (CBCT) on orthodontic diagnosis and treatment planning. METHODS Participant orthodontists shown traditional orthodontic records for 6 patients were asked to provide a diagnostic problem list, a hypothetical treatment plan, and a clinical certainty. They then evaluated a CBCT scan for each patient and noted any changes, confirmations, or enhancements to their diagnosis and treatment plan. RESULTS The number of diagnosis and treatment plan changes varied widely by patient characteristics. The most frequently reported diagnosis and treatment plan changes occurred in patients with unerupted teeth, severe root resorption, or severe skeletal discrepancies. We found no benefit in terms of changes in treatment plan for patients when the reason for obtaining a CBCT scan was to examine for abnormalities of the temporomandibular joint or airway, or crowding. Orthodontic participants who own CBCT machines or use CBCT scans frequently in practice reported significantly more diagnosis and treatment plan changes and greater confidence after viewing the CBCT scans during the study. CONCLUSIONS The results of this study support obtaining a CBCT scan before orthodontic diagnosis and treatment planning when a patient has an unerupted tooth with delayed eruption or a questionable location, severe root resorption as diagnosed with a periapical or panoramic radiograph, or a severe skeletal discrepancy. We propose that CBCT scans should be ordered only when there is clear, specific, individual clinical justification.

Influence of geometric distortion and exposure parameters on sensitivity of digital subtraction radiography

In the course of digital subtraction radiography (DSR), variation in the alignment of the x-ray source object and image receptor is an undesirable but frequent problem. The influence of angulation changes between the x-ray source and object on the quality of the subtracted image was measured with the visualization of a thin chip of bone (thickness less than or equal to 0.85 mm). Twenty radiographic image pairs that differed by known geometric distortions ranging from 0 to 9 degrees horizontal and vertical were subtracted. The ability to detect a thickness change varied strongly with angular distortion. Under optimal conditions (no distortion), DSR was able to detect a change in thickness of cortical bone of 0.12 mm. Under approximately clinical circumstances (3 degree misalignment), a thickness change of 0.35 mm was detected with 50% accuracy (three of six cases), while a thickness change of 0.42 mm was detected with 100% accuracy (six of six cases). In addition, the influence of exposure parameters on DSR was investigated. Twenty-one radiographic film pairs were subtracted with differing densities and contrasts. Images made at 70 kVp with an optical density of 0.61 in the dentin produced the best subtracted images. However, even images made with one fourth the conventional exposure produced diagnostic information when analyzed with DSR; this was not seen with conventional analysis of the normally exposed radiographic films.