Dentomaxillofacial Radiology (2005) 34, 91–95 q 2005 The British Institute of Radiology http://dmfr.birjournals.org
RESEARCH
The utility of panoramic radiography in temporomandibular joint assessment HC Crow*,1, E Parks2, JH Campbell3, DS Stucki4 and J Daggy5 1 Department of Oral Diagnostic Sciences, TMD and Orofacial Pain Program, University at Buffalo, Buffalo, NY, USA; 2Department of Oral Pathology, Medicine and Radiology, Indiana University School of Dentistry, Indianapolis, IN, USA; 3Department of Oral Maxillofacial Surgery, University at Buffalo, Buffalo, NY, USA; 4Indiana University School of Dentistry; currently in the private practice of dentistry, St. George, Utah, USA; 5Division of Biostatistics, Indiana University School of Medicine, Indianapolis, IN, USA
Objectives: Panoramic radiography was used to determine (1) intrarater and inter-rater reliability in assessing temporomandibular joint (TMJ) condylar morphology; (2) alteration in condylar shape in patients with temporomandibular disorders (TMD) and controls when matched by age, gender, and state of dentition; and (3) prevalence of condylar abnormalities in individuals with and without TMD. Methods: One hundred panoramic radiographs were randomly selected from a hospital clinic (45 TMD and 55 non-TMD patients). The images were cropped to include only the temporomandibular apparatus and were independently evaluated by three examiners without knowledge of the patient’s clinical status. Multiple statistical tests were performed to evaluate the accumulated data. Results: Intrarater reliability demonstrated substantial agreement, while inter-rater reliability was fair. There was no difference in condylar morphology between patient groups, but mild condylar change was prevalent in all age groups, regardless of TMD status. Conclusions: Morphological condylar abnormalities are present on panoramic images in all adult age ranges, regardless of status of the dentition or presence of TMD. Condylar shape alone is not an indicator of TMD, and minor condylar discrepancies may have no significance in TMD. Dentomaxillofacial Radiology (2005) 34, 91–95. doi: 10.1259/dmfr/24863557 Keywords: temporomandibular disorders; radiography, panoramic; temporomandibular joint Introduction Temporomandibular disorders (TMD) constitute a complex set of specific entities with a reported prevalence of 5 – 12%.1 – 3 TMD can be defined as pain and/or dysfunction in the muscles of mastication or temporomandibular joint (TMJ), and as such is a non-specific term. Given that patients with facial pain complaints may present with both joint and muscle pain symptoms as well as tenderness to palpation, it can be difficult to exclude joint pathology in TMD patients on initial clinical examination. Panoramic radiography has been recommended as a screening tool in patients with TMJ joint complaints,4 and may be appropriate for determining gross bony changes in the condyle.5 However, there can be a lack of correlation between radiographic findings and TMD symptomatology,6 and patients without TMD symptomatology can present with condylar changes demonstrated by panoramic imaging.7 *Correspondence to: HC Crow, DMD, MS, 355 Squire Hall, 3435 Main St., Buffalo, NY 14214, USA; E-mail:
[email protected] Received 5 March 2004; revised 6 December 2004; accepted 1 January 2005
In addition, concerns persist about intrarater and inter-rater reliability in evaluating joint morphology using panoramic radiography.6,8,9 Correlations between morphological changes and age must also be considered when evaluating panoramic radiographs.7,10 Finally, there is controversy as to whether or not the number of remaining teeth affects condylar morphology7,10 despite evidence that morphological changes in elderly individuals are not associated (or only weakly associated) with TMD signs or dental status.11,12 This study was designed to evaluate reliability and to determine if joint morphology could be associated with age, dental status, or pain. We attempted to determine if panoramic images of the condyle can be reliably assessed, both by the same evaluator at different times and by different evaluators. This is an important issue, since previous studies have demonstrated both acceptable,13 and unacceptable,9 reliability in evaluating condylar morphology. If reliability can be demonstrated, it is important to determine if radiographic findings correspond to the
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presence of jaw pain, patient age, dentition status, or some combination of these. Our hypotheses were that abnormalities in condylar shape would increase with age and that patients with TMD would demonstrate increased pathology at a younger age compared with non-TMD patients. Such findings would have direct clinical relevance to the use of panoramic radiography in TMD assessments. Materials and methods One hundred hospital records (45 from known TMD patients and 55 from non-TMD patients) were randomly selected for review through use of a random number table. Panoramic images were obtained from each chart, and abstracts of patient data, which included date of birth, date of radiographic evaluation, race, gender, occlusal status (fully dentate, partially dentate, edentulous), and presence or absence of TMD and subtype (myofascial pain, joint dysfunction subcategories, or both), were prepared. All images were taken prior to initial treatment in the dental clinic, with the same panoramic radiographic unit (PlanMeca, Helsinki, Finland) within a 5-year interval. Radiographs from the non-TMD patients were obtained prior to dental extraction in the Oral and Maxillofacial surgery clinic in patients with either odontogenic pathology or for third molar extraction. Radiographic images of each joint (200 total joints) were scanned into a computer database (grey scale mode), and cropped to include only the temporomandibular apparatus to avoid knowledge of the dentition status or bias from presumed age of the subject based on the dental condition. Images were saved as JPEG files (Figures 1 and 2), and were placed on a website to allow access from different locations. The website incorporated a guided questionnaire to allow standardized evaluation of condylar morphology. An oral and maxillofacial radiologist, a general dentist trained in management of TMD, and an oral and maxillofacial surgeon (each of whom received post-graduate training at different institutions) independently assessed the condylar morphology of each image without knowledge of the patient’s clinical status. By selecting clinicians with different training, we hoped to approximate patient care practice in the community. The clinicians utilized the
Figure 1
Panoramic image as originally scanned and saved in a JPEG file
Dentomaxillofacial Radiology
definitions and scoring system published by Muir and Goss,7 and were calibrated utilizing standard examples of osteophyte, erosion, flattening, sclerosis, concavity, and subcortical “cyst”. For each measure, a score of “zero” equated to no demonstrable change, “one” represented mild change, and “two” signified gross change. The protocol was approved and accepted as exempt research through the Institutional Review Committee. In order to assess intrarater reliability, 20 radiographic images from both patient and control subjects were selected at random and repeated within the database. Reliability within and between examiners was calculated utilizing a total score as well as individual scores for each of the six features. The total joint pathology score was calculated as the sum of scores for all measured variables (0 – 2 each for osteophyte, erosion, flattening, sclerosis, concavity, and subcortical cyst). Thus, a completely “normal” joint would be indicated by a score of zero, while a severely abnormal joint would score 12 (gross change in all 6 areas being evaluated). SAS Software, Version 8 (Cary, NC) was used for analysis. Interclass and intraclass correlation was calculated for this score to assess agreement between and within examiners, respectively, assuming examiners are random. Kappa statistics were computed for all response variables to assess agreement between examiners. The Kappa statistics were interpreted as , 0 ¼ poor agreement, 0.00 – 0.20 ¼ slight agreement, 0.21 – 0.40 ¼ fair agreement, 0.41 – 0.60 ¼ moderate agreement, 0.61 – 0.80 ¼ substantial agreement, 0.81 – 0.99 ¼ almost perfect agreement, and 1.00 ¼ perfect agreement.14 The total joint pathology score was summed over all three examiners for each image to determine the total composite score. Since the data were not normally distributed, a rank transformation was used. A mixed model was fit to compare the transformed score of patients with and without jaw pain, using side as a random effect. Age and gender were included as covariates. Parameter estimates were considered statistically significant if the P-value was less than 0.05. A subset of 23 patient records was able to be matched on age (within 5 years), gender, and state of dentition. State of dentition was categorized by edentulous, fully dentate (with or without third molars), or partially dentate.
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Figure 2 Cropped images of the temporomandibular apparatus shown on the website accessed by the evaluators. Right and left condylar images from the same patient were not shown in the same panel or sequentially
The partially dentate patients were assessed by evaluating opposing tooth contact per side and matched as closely as possible. Composite scores were obtained for each condylar image. Differences between matched pairs were analysed by paired t-test, with significance established at P , 0.05. A final analysis of prevalence was performed, utilizing composite scores averaged from the right and left joints. Also, prevalence of at least minor changes in the jaw joints was assessed across the population of TMD patients and non-TMD patients. Fisher’s Exact Test was used to test for an association between changes in osteophyte or flattening and TMD status. Results Images from 55 non-TMD patients (17 male, 38 female) and 45 TMD patients (6 male and 39 female) were evaluated. The median and mean age of non-TMD patients was 39 years (range 17 – 72 years), while the median age of TMD patients was 30 years and the mean age was 35 years (range 17 – 85 years). Reliability of the total joint score within examiners was good to excellent (intraclass correlations for examiners 1, 2, and 3 for total score were 0.83, 0.76, and 0.62,
respectively). The interclass correlation (ICC) for total score between examiners was adequate (ICC ¼ 0.31). Kappa statistics for between-examiner reliability of individual features varied by feature. There was poor agreement between examiners for presence of a concavity (2 0.07). There was slight agreement for erosion (0.07), sclerosis (0.03), and presence of subcortical cyst (0.17). There was fair agreement for presence of ostephytes (0.35) and flattening (0.29). When the data were analysed to determine if there were differences in total score between patients with and without jaw pain, no significance was found (P ¼ 0.44). Median scores for non-TMD and TMD patients after averaging across sides were 3.0 (0.5 – 8.0) and 3.5 (0.5 – 9.5), respectively. Since this total analysis did not take into account dental differences, a matched pairs analysis was conducted. Twenty-three of the charts could be matched on the basis of age (within 5 years), dentition (full, partially dentate, or edentulous) and gender. There were no statistical differences in condylar morphology between the patients with or without jaw pain when rigorously matched (t ¼ 1.17, df ¼ 22, P ¼ 0.26). The mean difference in total score between non-TMD patients and TMD patients was 0.52 with 95% confidence interval [2 0.41, 1.45]. As the data were being analysed, it became obvious that at least minor changes were present in many of the Dentomaxillofacial Radiology
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images, even in the youngest age groups. The scores of the three clinicians were averaged, and prevalence of at least minor changes in the condyles was determined. At least minor changes were present in 87% of the patients without jaw pain, and in 93% of the patients with jaw pain. When the images were divided into three age groups (17 – 30 years, 31 – 50 years, and 51 years and above), 91% of the younger TMD patients had at least minor remodelling, 93% of the middle age group, and 100% of the older age group had some condylar change. In the younger non-TMD patients, 90% demonstrated at least minor condylar change, with 81% of the middle age group and 93% of the older age groups demonstrating at least minor changes (Table 1). Prevalence of osteophytes or flattening was assessed since these characteristics demonstrated fair reliability among clinicians. There was no increased prevalence of osteophyte formation or flattening in the TMD group compared with the general dental group (Table 2). When degree of osteophyte or flattening was assessed (no change, mild, or gross change), there was no difference between the individuals with TMD and the general dental group.
Discussion This study utilized individuals trained to assess TMJ morphology on panoramic imaging. The intraexaminer reliability was good to excellent, with the highest agreement found within repeat observations from examiner 1, the maxillofacial radiologist. The inter-rater reliability was adequate for a pooled score of the six morphological changes assessed: presence of erosion, flattening, sclerosis, concavity, osteophyte and subcortical “cyst”, so an averaged score across the three clinicians was used to assess prevalence. Utilizing this approach, a high level of prevalence of at least minor changes in condylar morphology was found, even in young individuals, both with and without a history of TMD. Patient positioning has been shown to be crucial in panoramic imaging of the condyles. If the head is inclined posteriorly, the image of the condyle appears flattened and can simulate the presence of an osteophyte. Conversely, if the head is inclined anteriorly, the condyle may appear sclerotic.15 The high prevalence of minor condylar changes seen in both the TMD and general dental population could reflect positioning artefact, rather than remodelling. While the two populations utilized in the study had panoramic images taken from the same machine, there were multiple operators who obtained the images over a period of 5 years. Table 1
However, it seems unlikely that a consistent positioning error would have occurred across operators over this period of time. In another study, when panoramic radiography was compared with tomography (polytomography or spiral tomography) as the gold standard, specificity was high for the presence or absence of osteophytes (0.90) and condylar flattening (0.85), while sensitivity was unacceptable (0.29 and 0.33, respectively).13 This would indicate that when evaluating panoramic images for condylar flattening or presence of osteophytes, false positives are less likely, while false negatives can occur frequently. It would therefore be less likely that the high prevalence of osteophytes and condylar flattening found in this study is a false positive finding. Four to five percent of the images evaluated demonstrated gross change regarding osteophytes or flattening, which is consistent with previous findings. Rushton and colleagues found TMJ abnormalities in 4% of the panoramic images they evaluated from a set of 1817 “screening” films obtained from general dentists.16 The present study did not, however, demonstrate a difference in condylar morphology in patients with or without TMD. This is in contrast to Muir and Goss17, who found increased frequencies of osteophytes, erosion, and condylar flattening in their younger age groups of TMD patients compared with controls. They were aware, however, of which radiographs were from TMD patients and which were from non-TMD patients,7 which may introduce bias. The current study evaluated radiographs from both symptomatic and asymptomatic individuals in a masked fashion, without knowledge of whether the patients were being treated for TMD. Currently there is significant controversy regarding the utility of panoramic radiographic imaging in both general practice and when evaluating TMD patients.15,16 Recent articles do not support the use of panoramic radiography in diagnosis of TMD.18,19 A recent article in the Journal of the American Dental Association claims a panoramic image should be used when the goal is to identify gross osseous changes in the TMJ.20 This same article notes that panoramic radiography should not be used for screening of disease in the absence of signs or symptoms of a problem. In a general practice setting, there is support for use of panoramic radiography in patients with pain.21 It is apparent from our results in this study that a high prevalence of minor condylar changes can be identified in both TMD and non-TMD patients. This implies that minor morphological changes in the radiographic image of the condyle in TMD patients may have no relevance and
Prevalence of at least mild change in one aspect of joint morphology Non-TMD (n ¼ 55)
Age Groups (years) 17 – 30 31 – 50 51 and older TMD, temporomandibular disorder Dentomaxillofacial Radiology
TMD (n ¼ 45)
No change
At least mild change
No change
At least mild change
2 (10%) 4 (19%) 1 (7%)
18 (90%) 17 (81%) 13 (93%)
2 (9%) 1 (7%) 0
21 (91%) 14 (93%) 7 (100%)
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Prevalence of osteophyte formation and condylar flattening Osteophyte Fisher’s Exact Test P ¼ 0.2
Flattening Fisher’s Exact Test P ¼ 1.0
Non-TMD (n ¼ 55)
TMD (n ¼ 45)
Non-TMD (n ¼ 55)
TMD (n ¼ 45)
25 (45%) 23 (42%) 7 (13%)
26 (58%) 11 (24%) 8 (18%)
6 (11%) 41 (74%) 8 (15%)
5 (11%) 33 (73%) 7 (16%)
No change Mild change Gross change TMD, temporomandibular disorder
should not be used to infer a diagnosis. This does not imply that panoramic radiography has no place in diagnostic evaluation of the facial pain patient; it clearly has the potential to rule out dental or other diseases that mimic or contribute to facial pain. This study did not attempt to address this issue, since only the TMJ was visible for analysis. In conclusion, there is a high prevalence of at least minor condylar changes visible on panoramic imaging in all adult age groups, with or without TMD. We were unable to demonstrate increased condylar changes in either an older age group or in patients being treated in a TMD clinic as compared with those being treated for
odontogenic pathology. These findings suggest that panoramic radiography is of no more than limited value in diagnosis of TMD, and minor condylar discrepancies may have no significance in TMD.
Acknowledgments The authors would like to thank the Division of Biostatistics at Indiana University School of Medicine, in particular George Eckert, for their help with statistical design and analysis. The authors also thank Technology Services at Indiana University School of Dentistry for their help in designing the website.
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