INTERPRETATION OF LINEAR AND COMPUTED TOMOGRAMS IN THE ASSESSMENT OF IMPLANT RECIPIENT SITES

TOMOGRAPHY IS A RADIOGRAPHIC PROCESS that produces cross-sectional ima ges of bony structures within the body. The purpose of this study was to evaluate the accuracy of diagnostic measurements made by dental imp lant team members from linear tomograms of human cadaver mandibles. Fi ve partially edentulous cadaver mandibles were radiographed using line ar tomography (LT) and computer-assisted tomography (CT). From the tom ograms, each of four team members traced the perceived outer circumfer ence of the mandible and the inferior alveolar canal. Tomogram tracing s were compared to each other and to the equivalent CT cross-sectional image to determine the precision of the measurements. One mandible wa s sectioned to verify the accuracy of the CT images. Repeated measures analysis of variance of the measurements made from the LT and CT scan s showed significant statistical differences between team members. Mul tiple cross-sectional views facilitated identification of the inferior alveolar canal in the majority of CT scans, whereas image blurring in herent to LT resulted in the inability of team members to identify the canal in 14% to 50% of the images. Volume averaging within the Cr sli ce aperture was found capable of producing a magnification error of sh ort dense objects. CT and LT must both be interpreted cautiously becau se of innate technique pecularities that can lead to measurement error s. The wide variation in interpretation of the linear tomograms and fr equent inability to identify the inferior alveolar canal made this tec hnique less valuable than the reformatted CT when planning dental surg ical procedures.