1. A 3-D digital medical and dental modeling system, which comprises: a computer including a digital memory adapted for storing patient densitometry information, at least one input, and at least one output; an input subsystem including a signal source and a signal receptor; a signal source positioning subsystem including a positioning motor and adapted for mounting said signal source and said signal receptor, said positioning subsystem connected to said computer and 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 a patient's dental and/or orthopedic structure; an output device connected to said computer output and adapted for communicating condition information for said patient consisting of said 3-D digital model or relevant information for said patient derived from said model; said computer being adapted to access a general population baseline database of patient dental or orthopedic densitometry data including variables for age and gender, said computer also being adapted to create a plurality of baseline 3-D digital patient models created using said general population baseline database and said computer being further adapted for building a predictive, 3-D, digital general population, densitometry model for said patient based on information from said general population baseline database and from identified dental or orthopedic densitometry changes for said patient; and said computer being further adapted for performing automated digital comparisons of said identified dental or orthopedic densitometry changes for said patient with said predictive, 3-D, digital, general population, densitometry model for said patient.