Radiographic evaluation of mandibular posterior implant sites: correlation between panoramic and tomographic determinations.

The purpose of the present study was to compare bone height determinations of implant sites by different radiographic techniques. Available bone height was measured in regions posterior to the mental foramen on panoramic radiographs, and on tomographs where the faciolingual dimension was at least 5mm. The bone heights were recorded at 401 edentulous and dentate sites in 100 patients. The overall mean bone height (m +/- SD) was 11.25 +/- 3.29 mm on panoramic radiographs and 8.81 +/- 3.38 mm on tomographs. The correlation between the two radiographic techniques ranged from 0.36 to 0.91 if the material was stratified according to factors such as height of available bone, age, gender and the presence of teeth. Gender was significantly correlated to panoramic and tomographic measurements in all regions. However, the precision of predicted tomographic measurements by using a linear regression model was not significantly increased by including gender as an explanatory variable. For evaluation of available bone height in mandibular regions posterior to the mental foramen, tomography is recommended for all prospective implant sites.