英文摘要 |
To evaluate the accuracy of ridge height estimation of posterior mandible from panoramic radiography before dental implant placement placement. Thirty patients were included in the study. These patients received dental implant treatment at the National Taiwan University Hsopital (NTUH) between March and September of 2000. Panoramic radiography and cross-sectional and sagittal hypocycloidal tomography were performed on each patient with surgical stent in place. With the fixed magnification in the hypocycloidal tomography, the ridge height at the implant sites of posterior mandible can be measured with tomography as a standard to evaluate the magnification of panoramic radiography at the same sites. Accuracy of estimating ridge height, calculated according to the literature on panoramic radiography was also evaluated. The vertical magnification factor of the panoramic radiography range from 23% to 62% (mean: 37.4%, standard deviation:8.8%) which was significantly larger than 26% in tomography. In panoramic radiography, different vertical magnification (28% to 43%) could be observed at similar sites (e.g. #47) of the mandible. The ridge height estimated on the panoramic radiography was larger than the true ridge height. The magnification factor of panoramic radiography varied from case to case. Therefore, clinicians should be very careful in judging the ridge height of mandible from panoramic radiography when accuracy is required during implantation. |