Image quality in preimplant computerized tomography (CT) examinations made with different radiation doses (40 to 280 mAs) and scanning modes (standard and helical axial, 15-degree angled, and frontal) and in conventional spiral tomography (Scanora) was compared. Mandibular canal and alveolar bone crest visibility was evaluated in images from mandibular jaw segments. Visibility was unaffected by radiation dose in CT examinations except in frontal scanning, where a small actual difference was statistically significant. Differences among CT scanning modes and between CT and conventional spiral tomography were highly significant. Low-dose mandibular preimplant tomography can be performed with CT using lower-than-normal radiation doses or with conventional spiral tomography. Keywords: computerized tomography, dental implantation, mandible, radiation dose, x-ray tomography