What each modality shows
Panoramic radiography flattens both jaws onto a single curved 2D image. You see all teeth and surrounding bone in one shot, but with overlap, magnification distortion and no depth information. It's fast, cheap and low dose (9–24 μSv).
CBCT acquires a 3D volume of the same region. Every voxel has X, Y, Z coordinates, so you can measure depth, oblique angles and curved structures accurately. Cost and dose are higher (30–200 μSv typical).
When CBCT adds clinical value
Implant planning (3D bone volume, nerve canal location), impacted teeth where root resorption of neighbors is suspected, complex root canal anatomy or persistent symptoms after RCT, surgical extraction of teeth near vital structures, evaluation of pathology beyond a panoramic's 2D view, orthognathic and TMJ assessment.
For routine screening, eruption charts, gross caries detection or simple extractions, panoramic plus periapicals usually suffice and avoid unnecessary dose.