Tore A. Larheim

Reproducibility of rotational panoramic radiography: Mandibular linear dimensions and angles

The reproducibility of nine mandibular variables (linear dimensions and angles) assessed from panoramic radiographs with the Orthopantomograph 5 (Siemens) was investigated. Attention was given to the possible influence of recording the reference number of the head positioner with one or two radiographers. Two separate exposures of three groups of patients were made under different radiographic conditions, each group representing one method. Acceptable reproducibility was observed for the vertical and angular variables, the method variance being mostly within 3% of the total variance. Horizontal variables were clearly more unreliable. No statistically significant differences were observed between the reproducibility of the right and left sides. A negative correlation was found between the angular variables within two groups. For most variables, only small differences among the methods were found. The highest reliability was obtained when the same radiographer recorded the reference number of the head positioner and made both exposures. An accuracy study on five dried skulls showed an image magnification of approximately 18% to 21% for the vertical variables, whereas the gonial angle assessed from a panoramic film was almost identical to that measured on the dried mandible.

Current trends in temporomandibular joint imaging

Diagnostic imaging of the temporomandibular joint has undergone a revolutionary development during the last two decades. With advanced modalities we have been able to differentiate between different articular entities in patients with temporomandibular joint disorders. The purpose of this article is to review and discuss these modalities and their contribution to our present knowledge, with emphasis made on current trends in diagnostic temporomandibular joint imaging. The main section deals with diagnostic imaging of the subgroup of disorders with internal derangement caused by disk displacement including posttreatment imaging. Imaging of pathologic entities characterized by chronic inflammation such as rheumatoid arthritis are discussed in the second section. Finally, the potential of diagnostic imaging of infrequent conditions such as tumors is briefly reviewed. Magnetic resonance imaging has surpassed arthrography and computed tomography for the evaluation of most patients in these three subgroups. In patients who have various forms of disk displacements with or without accompanying bone abnormalities, a diagnostic accuracy of at least 90% may be achieved by oblique sagittal and coronal magnetic resonance imaging. In addition, alterations in the condylar marrow may be detected. T2-weighted magnetic resonance imaging can make a significant diagnostic contribution by demonstrating inflammatory reactions such as joint effusion and marrow edema. In the subgroup of patients with chronic inflammatory diseases, magnetic resonance imaging may also demonstrate abnormalities not shown with other imaging modalities. Disk deformation, fragmentation, and destruction may indirectly suggest the presence of synovial proliferation/pannus formation, which in selected cases may be directly depicted with intravenous gadopentetate dimeglumine. For more detailed evaluation of the bone condition and of soft tissue calcifications in joints with inflammatory diseases, tumors, or other disorders, computed tomography is the preferable imaging modality.

Role of Magnetic Resonance Imaging in the Clinical Diagnosis of the Temporomandibular Joint

Temporomandibular joint (TMJ) abnormalities cannot be reliably assessed by a clinical examination. Magnetic resonance imaging (MRI) may depict joint abnormalities not seen with any other imaging method and thus is the best method to make a diagnostic assessment of the TMJ status. In patients with temporomandibular joint disorder (TMD) referred for diagnostic imaging the predominant TMJ finding is internal derangement related to disc displacement. This finding is significantly more frequent than in asymptomatic volunteers, and occurs in up to 80% of patients consecutively referred for TMJ imaging. Moreover, certain types of disc displacement seem to occur almost exclusively in TMD patients, namely complete disc displacements that do not reduce on mouth opening. Other intra-articular abnormalities may additionally be associated with the disc displacement, predominantly joint effusion (which means more fluid than seen in any asymptomatic volunteer) and mandibular condyle marrow abnormalities (which are not seen in volunteers). These conditions seem to be closely related. Nearly 15% of TMD patients consecutively referred for TMJ MRI will have joint effusion, of whom about 30% will show bone marrow abnormalities. In a surgically selected material of joints with histologically documented bone marrow abnormalities nearly 40% showed joint effusion. Disc displacement is mostly bilateral, but joint effusion seems to be unilateral or with a lesser amount of fluid in the contralateral joint. Abnormal bone marrow is also mostly unilateral. Many patients have unilateral pain or more pain on one side. In a regression analysis the self-reported in-patient TMJ pain side difference was positively dependent on TMJ effusion and condyle marrow abnormalities, but negatively dependent on cortical bone abnormalities. Of the joints with effusion only one fourth showed osteoarthritis. Thus, there seems to be a subgroup of TMD patients showing more severe intra-articular pathology than disc displacement alone, and mostly without osteoarthritis. It should, however, be emphasized that patients with TMJ effusion and/or abnormal bone marrow in the mandibular condyle seem to constitute only a minor portion (less than one fourth) of consecutive TMD patients referred for diagnostic TMJ imaging. The majority of patients have internal derangement related to disc displacement, but without accompanying joint abnormalities. In patients with rheumatoid arthritis and other arthritides TMJ involvement may mimick the more common TMDs. Using MRI it is possible, in most cases, to distinguish these patients from those without synovial proliferation.

Osteonecrosis of the temporomandibular joint: correlation of magnetic resonance imaging and histology.

PURPOSE The aims of this study were to investigate whether osteonecrosis affects the mandibular condyle and to determine whether this condition could be diagnosed with magnetic resonance imaging (MRI). MATERIALS AND METHODS The study was based on 50 temporomandibular joints in 44 patients in whom MRI and surgery were performed for painful internal derangements. At the time of surgery, a core biopsy specimen was obtained from the marrow of the mandibular condyles, and the histological observations were correlated to T1-(proton density) and T2-weighted MR images. RESULTS Histological evidence of osteonecrosis was found in nine joints (18%). Bone marrow edema, which may be a precursor of osteonecrosis, was found in nine other joints. The MRI was 78% sensitive and 84% specific for the diagnosis of osteonecrosis of the mandibular condyle. However, the positive predictive value was only 54% because of a number of false-positive MRI diagnoses. CONCLUSION Osteonecrosis can affect the mandibular condyle, and this condition can be diagnosed with MRI. A combination of edema and sclerosis of the bone marrow was the most reliable MRI sign of osteonecrosis. The cause, its clinical significance, and the need for treatment are unknown.

The Temporomandibular Joint in Juvenile Rheumatoid Arthritis: Radiographic Changes Related to Clinical and Laboratory Parameters in 100 Children

A prospective study of 100 children aged 2-17 years (68 girls) with juvenile rheumatoid arthritis (JRA) was initiated to follow changes in the temporomandibular joint (TMJ), growth of the craniofacial complex and development of the dental occlusion, and to relate the findings to clinical and laboratory parameters. The mean age at onset was 5.5 years. The debut type was acute febrile in 14, pauciarticular in 64, and polyarticular in 22 patients. At examination, at mean age 9 years, 45 patients had pauci- and 55 polyarticular JRA. Definite radiographic TMJ changes were found in 41 patients (unilaterally in 17). 130 children without joint disease served as controls. Of the patients with radiographic TMJ changes, 65% had clinical symptoms and/or signs, the most frequent being restricted mouth opening. Of the patients without radiographic TMJ changes, 19% had uncertain clinical findings (pain, tenderness or slightly restricted mouth opening). Radiographic TMJ changes were significantly related to early onset of JRA, long disease duration, actual polyarticular type, high disease activity, impaired functional capacity and general health, splenomegaly and kidney involvement, low hemoglobin and high gammaglobulin concentrations. A significant relationship was also found with radiographic changes of the cervical spine. Radiographic examination seemed essential for the diagnosis of TMJ arthritis.

Intraoral storage phosphor radiography for approximal caries detection and effect of image magnification : Comparison with conventional radiography

OBJECTIVES The aim of this study was first to test the newly developed storage phosphor (SP) system Digora for diagnostic accuracy of approximal caries detection with special emphasis on image magnification compared with conventional radiography, and second, to test whether the image surroundings could have an influence on observer performance. DESIGN SP plates and Ektaspeed films were exposed simultaneously to 50 extracted premolars/molars, and the SP image files were transported to a different platform for processing. Ten observers rated 95 approximal surfaces for caries with four imaging modalities: (1) SP images at dental film size viewed with black surroundings, (2) magnified (x4) images viewed in the same manner, (3) magnified (x4) images viewed with text and graphics framing, and (4) films viewed on a light box. The observations were validated with microscopy. Diagnostic accuracy was calculated as the area beneath the receiver operating characteristic curve (AZ). RESULTS No significant differences were found between SP images and films. Magnified SP images with text and graphics demonstrated significantly higher AZ values than nonmagnified images both for enamel and dentin, and magnified images with black surroundings demonstrated similar results for dentin. CONCLUSIONS In this in vitro material the observer performance for approximal caries detection with SP images was comparable to that with Ektaspeed films. The magnified SP images generally showed a significantly higher diagnostic accuracy than the nonmagnified SP images.

Temporomandibular Joint Involvement and Dental Occlusion in a Group of Adults with Rheumatoid Arthritis

The temporomandibular joint (TMJ) and dental occlusion were investigated clinically and radiographically in 59 patients aged 23-83 (mean, 58) years with general joint disease. Forty-nine had rheumatoid arthritis (RA), mostly of long duration. The patients were divided into four groups by type of dentition. Radiographic TMJ abnormality was found in about 4 of 5 patients with RA, in both the dentate and the edentulous group. The abnormality was mainly destructive with productive signs, but in the edentulous group erosive and asymmetrical changes occurred more often. Almost complete restriction of the condylar translation and severely restricted mouth opening (less than or equal to 30 mm) rarely occurred, although the translatory motion was restricted in several patients. Many of these had a satisfactory mouth opening (greater than 40 mm). Occlusal changes-various degrees of anterior bite opening-were reported by about one fourth of both the dentate patients and the complete denture wearers. One patient had occlusal contact on the second molars only. Anterior bite opening occurred only in patients with radiographic TMJ abnormality, including 5 of the 6 patients with complete mandibular head destruction.

The Association of Temporomandibular Joint Pain With Abnormal Bone Marrow in the Mandibular Condyle

PURPOSE This study investigated the association between temporomandibular joint pain and bone marrow alterations in the mandibular condyle seen on magnetic resonance (MR) images. PATIENTS AND METHODS The study was based on 112 temporomandibular joints in 112 patients with disc displacement without reduction. Thirty-four patients with abnormal bone marrow on MR images were compared with a control group of 78 patients with normal bone marrow. The analysis was based on proton density and T2-weighted MR images in the oblique sagittal and coronal planes. The degree of pain was correlated to the status of the bone marrow using statistical methods. RESULTS The degree of pain in joints with abnormal bone marrow was higher than in joints with normal bone marrow signal on MR images (P = .0045). CONCLUSION Because the stage of internal derangement was similar in both groups, more intensive pain appears to be associated with bone marrow alterations.

Temporomandibular joint findings in adults with long-standing juvenile idiopathic arthritis: CT and MR imaging assessment.

PURPOSE To assess the long-term temporomandibular joint (TMJ) manifestations of juvenile idiopathic arthritis (JIA), as depicted at computed tomography (CT) and magnetic resonance (MR) imaging, in 47 adult patients. MATERIALS AND METHODS The study was approved by a regional committee for medical research ethics, and informed consent was obtained from all patients. Forty-seven patients with JIA (32 women, 15 men; mean age, 35 years) were examined, on average, 30 years after the initial diagnosis. The findings of TMJ imaging, including CT and MR imaging, were evaluated by three observers. Bone and disk abnormalities, joint effusion, bone marrow abnormalities, and contrast enhancement were analyzed. RESULTS The TMJs were involved in 33 (70%) of the 47 patients with JIA, with bilateral involvement in 29 patients. Slight to moderate contrast enhancement was observed on the images obtained in 14 (42%) of the 33 patients with TMJ JIA abnormalities. All main joint components were abnormal in 28 of the 33 patients, mainly showing flat deformed condyles, wide flat fossae, and thin or perforated disks in the normal position, or absent disks. Condylar concavity or bifidity, and secondary osteoarthritis were found in approximately half of the abnormal joints. CONCLUSION Long-term JIA manifestations in the TMJs, as demonstrated at CT and MR imaging, were frequent, usually bilateral, and characterized by mandibular condyle and temporal bone deformities, abnormal disk morphology, and, rather frequently, osteoarthritis and mild synovitis.

Reproducibility of radiographs with the orthopantomograph 5: tooth-length assessment.

The precision of tooth-length assessments based on repeated panoramic radiographs made with a Siemens OP 5 was investigated in three groups of twenty patients. Two exposures of the same patient were made under three different radiographic conditions. Of the tooth lengths, nonmeasurability was found in 14% to 17%. The variability (standard deviation) of the measurements assessed from repeated radiographs ranged from 0.65 to 0.85 mm, or 2.4% to 3.1% of the mean radiographic tooth length in the different patient groups. The measurement error ranged from 0.43 to 0.56 mm, indicating that the main source of error inherent in the method was recognition of the reference points. Small differences were found between the tooth groups and between the right and left sides.