In dentistry, there is a special type of CT scan called Cone Beam Imaging.  A cone beam scanner puts out at least 300 times less radiation than a conventional medical CT scan, and the images it creates are far superior.  The benefit of a cone beam CT scan is that things can be diagnosed and treated in 3D instead of in a flat 2D aspect, since the body is a three dimensional object.  

A 3D CT scan is used to diagnose diseases such as hard tissue lesions that may involve cysts and tumors.   More commonly, a 3D CT scan is taken to determine bone height, width, volume, quality, density, and quantity.  A scan can also be used to plan implant placement in computer software.  That plan can then be sent to a lab to create a surgical template, which assists with placing implants in the ideal position.

Diagnosing and treatment planning in 3D provides incredible accuracy and incredible power to see things that were never seen before, and cannot be seen any other way.  Since the radiation dose is so low, it gives us a much better opportunity to be able to diagnose and/or treat in a way that has never been done before.