1. A 3-D digital medical and dental modeling system, which comprises: a computer including a digital memory adapted for storing patient densitometry information, an input and an output; an input subsystem including a signal source and a signal receptor; a signal positioning subsystem connected to said computer and mounting said source and receptor, said positioning subsystem being adapted for moving said source and/or said receptor through a predetermined path of movement relative to a patient; said receptor being connected to the computer input; said receptor producing signals to said computer input representing a condition of the patient's dental and/or orthopedic structure; said computer being adapted for creating, storing and comparing 3-D digital models of patient dental and/or orthopedic structure; and an output device connected to said computer output and adapted for communicating patient condition information consisting of or derived from a respective said 3-D digital model.