comparison of the diagnostic accuracy of the Cone Beam Computed Tomographys (CBCTs) and Orthopantomogaphs (OPGs): clinical and medico-legal issues

BACKGROUND Since a long time the OPG is the most widespread prescribed radiological examination. The introduction of digital imaging has allowed the reduction of the exposition dose and an important improvement in the quality of the images. Moreover, some three-dimensional radiological examinations, and CBCTs among them, are getting ever more used in dental diagnostic routine since they are nowadays a relatively inexpensive and easy accessible tool and provide accurate examination. Particularly a CBCT scan allows to accurately detect the site and dimension of oral pathological conditions which the OPGs, on the contrary, cannot definitely recognize, and implies very low radiation doses in comparison to the traditional CT. As such, the CBCT scan may become a recommended procedure in specific clinic conditions and omitting its prescription may raise medico-legal and ethical issues. AIM The aim of the present study is to evaluate the different diagnostic accuracy of CBCT compared with that proper to a digital OPG. MATERIALS AND METHODS A total of 187 upper and lower dental arches CBCTs and OPGs, performed for ordinary clinical purposes in the same day, in the same radiology office and with the same devices, have been submitted for the comparison to two general dentists. The operators examined the OPGs at first and the CBCTs after 1 week, and listed in details every detectable oral pathological condition or anomaly (transparencies, opacities,etc). The difference in diagnostic accuracy between the two exams has been evaluated. The intra-operator variability has also been evaluated re-submitting the 10% of the exams to the operators after two weeks. The inter-operator variability is also evaluated. RESULTS Even if the research is still in progress, it is already clear that the CBCT exam allows to obtain a more accurate diagnostic evaluation of the oral clinical conditions than the OPG exam does. The CBCT particularly allows to reveal more precisely the site and the actual dimensions of the pathological processes of the maxillary bones, which are by the OPG only poorly or not at all detectable. In most samples, at least one lesion not revealed by OPG is clearly showed by the CBCT, especially for periapical radiotrasparencies of endodontically treated teeth. The most striking cases will be described and discussed. Hence, the ethical as well as the medico-legal implications will be discussed in terms of appropriateness of the two different radiological examinations, given their radiation dose, the costs and the difference in accuracy and efficacy in specific diagnostic procedures. The related medico-legal issues deserve further discussion to define the different radiological approaches and the possible implications in terms of standard of care.