Negative and positive merge modelling

A system for producing a virtual three-dimensional dentition model for modelling a patient's prepared tooth for assisting in preparing and fitting a prosthetic therefor, comprising:

• one or more computing devices;
• one or more scanning devices communicatively coupled to the computing device;
• and
• a memory storing instructions, the instructions executable by the one or more computing devices and/or scanning devices;
• wherein the instructions comprise:
• scanning, by the one or more scanning devices, a negative impression of the patient's dentition, including at least the teeth surrounding and including the prepared tooth, to create optionally with said computing device a negative virtual three-dimensional impression model;
• scanning, by the one or more scanning devices, a positive die created from a negative impression of the patient's dentition, which is a positive representation of a limited part of the patient's dentition containing at least the prepared tooth, to create optionally with said computing device a positive virtual three-dimensional die model;
• inverting, by the one or more computing devices, the negative virtual three-dimensional impression model to create a positive virtual three-dimensional impression model;
• and
• merging, by the one or more computing devices, the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model to create a virtual three-dimensional dentition model.

A non-transitory computer-readable medium storing instructions, which when executed cause one or more processors to:

• scan a negative impression of the patient's dentition, including at least the teeth surrounding and including the prepared tooth, to create a computer-generated negative virtual three-dimensional impression model;
• scan a positive die created from a negative impression of the patient's dentition, which yields a computer-generated positive virtual three-dimensional die model representative of a limited part of the patient's dentition containing at least the prepared tooth;
• invert the negative virtual three-dimensional impression model to create a positive virtual three-dimensional impression model;
• and
• merge the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model to create a virtual three-dimensional dentition model.