Three-dimensional occlusal and interproximal contact detection and display using virtual tooth models
A method for monitoring tooth wear and a method for monitoring tooth wear and gingival recession and erosion by comparing three-dimensional virtual models at different times are described, as well as occlusal contact between upper and lower virtual three-dimensional teeth of a patient when the upper and lower arches are in an occluded 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 monitoring tooth wear, and gingival recession and erosion, comprising the steps of:
in-vivo scanning a portion of the patient's dentition at a first point in time using a hand-held scanner; where in said portion of the patient's dentition comprises teeth and gingival tissue;
obtaining a first three-dimensional virtual model of said portion of the patient's dentition at said first point in time;
in-vivo scanning said portion of the patient's dentition at a second point in time using said hand-held scanner; where in said second point in time is later than said first point in time;
obtaining a second three-dimensional virtual model of said portion of the patient's dentition at said second point in time;
comparing said first and second virtual models to each other; and
identifying, from said step of comparison, portions of said first three-dimensional virtual model that are missing from said second three-dimensional model; where in said portions missing from said second three-dimensional model comprise tooth wear, and gingival recession and erosion.
2. The method of claim 1 , wherein said step of comparing comprises the step of subtraction of said second three-dimensional model from said first three-dimensional model.
3. A method of monitoring toot wear, comprising the steps of:
1) obtaining a first three-dimensional virtual model of a portion of the patient's dentition at a first point in time, wherein said first virtual model comprises a virtual model of the upper and lower arches;
2) obtainig a second three-dimensional virtual model of said portion of the patient's dentition at a second, later point in time; wherein said second virtual model comprises a virtual model of the upper and lower arches;
3) determining occlusal contact areas of said upper and lower arches for said first three-dimensional model;
4) determining occlusal contact areas of said upper and lower arches for said second three-dimensional model;
wherein in steps 3) and 4) determining said occlusal contact areas comprises:
a) calculating, with said three-dimensional virtual model of a portion of the patient's dentition, distances characterizing the occlusal relationship 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 when said arches are 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
whereby a comparison of said occlusal contact areas from step 4) with said occlusal contact areas of step 3) provides an indication of tooth wear with an increase in occlusal contact area indicating tooth wear.
4. The method of claim 3 , wherein steps 3) and 4) comprise quantitative measurements of said occlusal contact areas.
5. The method of claim 4 , wherein steps 1)-4) are performed in a general purpose computer and wherein said quantitative measurements are performed automatically by said computer.