Introduction: For implant planning, clinical evaluation, model study, radiographic exams are necessary. Through the radiographic exams, alveolar bone and basal bone quantity and quality could be evaluated. It is very important to determine the location and length of the implant. Panorama is simple and it shows the maxilla and mandibular anatomical structures at a glance. However, the image is different from the anterior and posterior / horizontal and vertical magnification. Cone-Beam CT(CBCT) is accurate and there is no overlap of the surrounding tissue. However, the relatively long exposure time can cause errors due to patient motion. Two different imaging modalities used for pre-implant assessment were compared in this study: panorama and CBCT reformatted panoramic images. Patients & Method: Twenty-two Patients(42 implant sites) with edentulous state on premolar and molar regions were included in this study conducted between June 2014 to February 2015. In each patient, panorama(Vatech, Korea) and reformatted panoramic image from CBCT(Vatech, Korea) using Simplant®(Materialise, Belgium) were compared . Distance from the maxillary sinus and inferior alveolar nerve to alveolar crest were compared at premolar and molar regions. Result: The length measurement error appeared to vary from 0.19 ~ 7.1mm. The average error was 2.65 mm between Panorama and reformatted panoramic image. In mandible, the length was measured longer on all implant sites digital panorama than CBCT reformatted panoramic images, however, in maxilla it did not show significant differences in the length measurement. Conclusion: If the length is insufficient (less than 10mm) in panorama, CBCT exam is considered to be necessary especially in mandible. Keywords: CBCT, Panorama, Dental implant