Stacy Geisler DDS, PhD
Axially corrected sagittal tomography (ACST) is currently the imaging modality of choice for diagnosing erosions and osteophytes of the tempromandibular joint (TMJ).
Based solely on evidence from dry skulls and autopsy specimens, the lack of information on clinical signs and symptoms limits the generalizability of the results of this study.
What is the ability of different types of imaging technologies in diagnosing erosions and osteophyte formation in the TMJ?
The authors conducted an exhaustive all-language search of 9 electronic databases for studies conducted from 1966 to 2006. The authors only included studies that derived data from autopsy specimens or dry skulls to confirm diagnosis of erosion and/or osteophyte formation using a radiological imaging modality. They excluded studies whose patients had pre-existing arthritis. The search identified 196 studies; only 9 studies met all inclusion criteria.
The authors of the review found that panoramic imaging is capable of identifying only extensive erosions and large osteophytes. Axially corrected sagittal tomography (ACST) is the most valid tool for diagnosing erosions and osteophyte formation in the TMJ, especially in the sagittal plane. The technique fairs comparably with conventional tomography (CT) when imaging the entire TMJ. Cone beam computed tomography (CBCT) appears to have the same capability for diagnosing erosions and osteophyte formation as helical CT (HCT) but is more cost effective and dose effective.
Based on evidence from autopsy specimens and dry skulls, the authors of the review concluded that ACST is currently the imaging modality of choice. CBCT, a promising new technology, is more cost effective and exposes patients to lower doses of radiation as compared to HCT. Diagnostic studies that simultaneously evaluate all imaging modalities and correlate with clinical signs and symptoms are needed.
Source of Funding:
Importance and Context:
According to the National Institutes of Health, approximately 10 million Americans are affected by tempromandibular dysfunction and usually present to a dentist with a complaint of pain or joint locking, clicking or popping. Evidence that radiography of the TMJ improves diagnosis and treatment decision and at the same time decreases patient lifetime radiation dose and health care costs, is needed before the radiographs are routinely used to guide treatment decisions.
Strengths and Weaknesses of the Systematic Review:
Although the authors conducted a comprehensive and systematic search, they presented the results in narrative form without any tables summarizing results. In addition, the number of final selected articles shown in the figure does not correspond to the results reported in the text. Results would have been strengthened by providing a table with the specific outcomes examined for each study. Statistics related to intra-examiner reliability would have also been useful in weighing the evidence between the various studies.
Strengths and Weaknesses of the Evidence:
Although the authors attempted to “evaluate the ability of different imaging modalities to diagnose the presence of TMJ erosions and osteophyte formation,” they included only studies whose data derived from autopsy specimens or dry skulls. Direct visual detection of degenerative pathology in dry skulls and autopsy specimens is the best confirmation for presence of disease. However, the lack of correlation with clinical signs and symptoms precludes any clinical applicability for disease diagnosis.
Implications for Dental Practice:
The systematic review does not provide reliable evidence that can be used to determine the diagnostic accuracy of an imaging modality for patients with TMJ disorders. Before justifying the use of diagnostic radiation, evidence is needed to demonstrate improved patient outcomes that offset the harms associated with increased radiation doses. While the authors make several conclusions as stated in the structured abstract above, results from the autopsy specimens without information on clinical signs and symptoms suggest possible values for sensitivity and specificity that might be obtained in vivo to detect erosions and osteophyte formation in the TMJ but have limited applicability to draw clinically relevant conclusions on accuracy of imaging modalities. [References: National Institute of Dental and Craniofacial Research. National Institutes of Health. TMJ Disorders. http://nidcr.nih.gov/OralHealth/Topics/TMJ/TMJDisorders.htm. NIH Publication No. 06-3487. Accessed on March 9, 2009.]