Three-dimensional occlusal and interproximal contact detection and display using virtual tooth models
Occlusal contact between upper and lower virtual three-dimensional teeth of a patient when the upper and lower arches are in an occlused condition are determined and displayed to the user on a user interface of a general purpose computing device. Various techniques for determining occlusal contacts are described. The areas where occlusal contact occurs is displayed on the user interface in a readily perceptible manner, such as by showing the occlusal contacts in green. If the proposed set-up would result in a interpenetration of teeth in opposing arches, such locations of interpenetration are illustrated in a contrasting color or shading (e.g., red). The ability to calculate distances and display occlusal contacts in a proposed set-up assists the user in planning treatment for the patient. The process can be extended to interproximal contact detection as well. The concepts also apply to dental prosthetics, such as crowns, fillings and dentures.
1. A method of evaluating a proposed set-up of teeth in planning treatment for an orthodontic patient, comprising the steps of:
obtaining a three-dimensional digital model of the teeth of the upper and lower arches;
moving said teeth to a proposed set-up for treating the patient;
calculating distances between portions of said teeth in said upper and lower arches when said teeth are positioned in an occluded condition; wherein said step of calculating includes, for a plurality of points on a surface of a tooth, the step of calculating a sphere around each of said points, and enlarging the size of the sphere until the sphere intersects with a surface of a tooth on the opposing arch in said model; and
displaying said teeth to a user in a manner such that said user can readily distinguish portions of said teeth in said upper and lower arches in which the distance between said portions is less than a predetermined threshold.
2. The method of claim 1 , wherein said predetermined threshold is adjustable by the user.
3. The method of claim 1 , wherein said portions of said teeth are displayed in a contrasting color relative to other portions of said teeth in which said calculations of distances results in distances greater than said threshold.
4. The method of claim 1 , wherein said step of calculating results in a determination that a portion of a tooth of one of said arches intrudes into a portion of a tooth of the other of said arches, and wherein the method further comprises the step of displaying on a user interface the said portions of said tooth in a manner such that a user can readily distinguish said portions.
5. A machine for assisting a user in planning treatment for an orthodontic patient, comprising:
a central processing unit;
a user interface; and
memory storing a set of instructions for said central processing unit and a data set representing a set of virtual teeth of a patient including the teeth of an upper arch and a lower arch;
said instructions comprising treatment planning software enabling a user to move the virtual teeth to a proposed set-up;
wherein said instructions further comprise a set of instruction for determining at least one occlusal contact of said upper and lower arches of said virtual teeth in said proposed set-up when said virtual teeth are in an occluded condition; wherein said set of instructions calculates a sphere around points on a surface of virtual teeth in one of said arches, and enlarges the size of said sphere until intersection of said sphere with a surface of a tooth on the opposing arch occurs thereby finding the separation distances between said virtual teeth in said opposing arches thereby enabling determining said at least one occlusal contact; and
wherein said set of instructions includes instructions for display of said virtual teeth on said user interface with said occluded contact displayed in a manner readily observable to said user.
6. The machine of claim 5 , wherein the proposed set-up would result in interpenetration of a tooth of one arch into a tooth of the opposing arch and said set of instructions displays on said user interface the location of said interpenetration in a manner such that a user can readily observe said location.
7. The machine of claim 5 , wherein said set of instructions further comprises an instruction permitting the user to adjust a distance variable indicative of an occlusal contact.
8. The machine of claim 5 , wherein said set of instructions includes a separation distance parameter indicative of an occlusal contact.
9. A method for determining the proximity of teeth of upper and lower jaws of an orthodontic patient, comprising the steps of:
a) storing data representing a three-dimensional model of teeth from the upper and lower arches of the patient in a memory associated with a computer;
b) simulating motion of said upper and lower arches relative to each other; and
c) calculating, with said computer and model, distances between surfaces of teeth in one of said upper and lower arches and surfaces of teeth in the other of said upper and lower arches during said simulation of motion; wherein said step of calculating includes the step of calculating a sphere around a plurality of points on a surface of a tooth in said one arch of said model, and enlarging the size of the sphere until the sphere intersects with a surface of a tooth on the opposing arch in said model.
10. The method of claim 9 , wherein said simulation of motion comprises a simulation of a closing of said upper and lower arches.
11. The method of claim 9 , wherein said simulation of motion comprises a simulation of a chewing motion of said upper and lower arches.
12. The method of claim 9 , further comprising the step of providing a user interface for displaying said three-dimensional model, displaying at least one tooth of said upper and lower arches on said user interface, and indicating on said display information associated with said calculations.
13. The method of claim 12 , wherein said step of indicating comprises the step of displaying portions of said model in a contrasting color or shading relative to other portions of said model in which said distance between said portions is less than a predetermined threshold.
14. The method of claim 12 , wherein said step of calculating results in a determination that the distances between portions of teeth in the upper and lower arches is less than or equal to zero, and wherein said portions are illustrated in a contrasting color or shading relative to other portions of said model.
15. The method of claim 9 , wherein said three-dimensional model of teeth comprises a model of a proposed arrangement of teeth in the upper and lower arches for planning orthodontic treatment of said patient.
16. The method of claim 9 , wherein said three-dimensional model of teeth comprises a model of an initial malocclusion of the patent.
17. The method of claim 9 , wherein said three-dimensional model of teeth comprises a model of an intermediate position of teeth during the course of treatment of said patient.