EP-4740901-A2 - METHOD TO SEMI-AUTOMATICALLY DETERMINE VIRTUAL DENTAL OCCLUSION

Abstract

Certain aspects of the present disclosure provide for a method of determining a virtual occlusion. The method may include obtaining a 3-D representation of a patient's first and second jaw portions. The method may further include, with the 3-D representation, representing in a GUI an initial position of the first jaw portion relative to the second jaw portion, the initial position being defined by six pre-determined degrees of freedom relative to a coordinate system fixed relative to the first jaw portion. The method may further include receiving user input of changes at least one degree of freedom, and automatically adjusting at least one other degree of freedom to minimize a vertical distance of the control point to the origin, thereby determining a virtual occlusion. The method may further include representing, in the GUI, the first and second jaw portions in the determined virtual occlusion.

Inventors

• BARTELS, Ward
• VAN DIJCK, Christophe

Assignees

• Materialise NV

Dates

Publication Date

20260513

Application Date

20221013

Claims (17)

1. A computer-implemented method of determining a virtual occlusion, comprising: obtaining a 3-D representation of a patient's first jaw portion and the patient's second jaw portion, the second jaw portion being opposite to and moveable with respect to the first jaw portion; with the 3-D representation, setting and representing in a graphic user interface (GUI) an initial position of the second jaw portion relative to the first jaw portion, the initial position being defined by a control point on the second jaw portion and the second jaw portion having six pre-determined degrees of freedom relative to a coordinate system with an origin fixed relative to the first jaw portion; receiving user input of changes to at least one of the degrees of freedom; automatically adjusting at least one of the other degrees of freedom to minimize a vertical distance of the control point to the origin while constraining distances between opposed surfaces of the first and second jaw portions to be positive, thereby determining an occlusion between the first and second jaw portions; and representing, in the GUI, the first and second jaw portions in the determined occlusion; said method further comprising: receiving user input indicating a region of at least one of the first and second jaw portions and assigning a maximum burring depth to said region; and generating at least one modified 3-D model representing the at least one of the first and second jaw portions based on the indicated region and the maximum burring depth, wherein automatically adjusting at least one of the other degrees of freedom comprises constraining distances between opposed surfaces of the first and second jaw portions to be positive based on the at least one modified 3-D model.
2. The method of claim 1, wherein generating the at least one modified 3-D model comprises altering an unmodified 3-D model of the at least one of the first and second jaw portions before burring to generate the at least one modified 3-D model, said altering comprising a translation of parts of said unmodified 3-D model representing the region indicated by the user input towards an inside of said unmodified 3-D model.
3. The method of claim 2, wherein the translation comprises a translation in a single direction, such as a downward translation when the at least one of the first and second jaw portions is a mandible or an upward translation when the at least one of the first and second jaw portions is a maxilla.
4. The method of claim 2, wherein the translation comprises a surface offset with a negative distance.
5. The method of any one of claims 1-4, wherein the GUI further comprises an occlusionogram of at least one of the first jaw portion and the second jaw portion.
6. The method of claim 5, further comprising displaying contact points between the first and second jaw portions in the determined occlusion on the occlusionogram.
7. The method of claim 5 or 6, further comprising displaying approximate contact points between the first and second jaw portions in the determined occlusion on the occlusionogram.
8. The method of any one of claims 5-7, further comprising displaying a convex hull around contact points and/or approximate contact points between the first and second jaw portions in the determined occlusion on the occlusionogram.
9. The method of any one of claims 5-8, wherein the occlusionogram is calculated based on the at least one modified 3-D model.
10. The method of any one of claims 5-8, wherein the occlusionogram is calculated based on unmodified 3-D models of the patient's first and second jaw portions before burring.
11. The method of any one of claims 1-10, wherein: the first jaw portion comprises at least part of the patient's maxilla, and the second jaw portion comprises at least part of the patient's mandible.
12. The method of any one of claims 1-10, wherein: the first jaw portion comprises at least part of the patient's mandible, and the second jaw portion comprises at least part of the patient's maxilla.
13. The method of any one of claims 1-12, wherein the GUI comprises a 3-D model of each of the first jaw portion and the second jaw portion.
14. The method of claim 13, further comprising displaying a distance between the first and second jaw portions in the determined occlusion as a color map on the 3-D model.
15. The method of any one of claims 1-14, further comprising updating the representation of the first and second jaw portions in the GUI in the occlusion determined in response to additional user input of changes to at least one of the degrees of freedom and corresponding automatic adjustments of at least one of the other degrees of freedom.
16. A computer-implemented method of forming a surgical guide based on a determined virtual occlusion, comprising: determining a virtual occlusion of a patient's first jaw portion and the patient's second jaw portion according to the method of any one of claims 1-15; and forming a surgical guide to guide the patient's teeth into the determined occlusion during orthognathic surgery, preferably wherein forming the surgical guide comprises manufacturing the surgical guide using an additive manufacturing technology.
17. A system for determining a virtual occlusion, comprising: a graphic user interface (GUI); and a processor configured to execute the method of any one of claims 1-15.

Description

CROSS REFERENCE TO RELATED APPLICATION This application claims benefit of and priority to U.S. Provisional Patent Application No. 63/266,079, filed December 28, 2021. BACKGROUND Field of the invention Aspects of the present disclosure relate to determining occlusion. In some aspects, the present disclosure relates specifically to devices, systems and methods for determining virtual occlusion for orthognathic surgery planning. Description of the Related Technology In orthognathic surgery, a surgeon performs an osteotomy to reposition the teeth of one or both jaws, aiming to alleviate clinical and esthetic problems caused by severe jaw misalignment that orthodontics alone cannot treat. Computer-assisted planning systems (such as Materialise's® ProPlan CMF, SurgiCase®, Mimics®, and the like) can help the surgeon predict the functional and esthetic outcome of the procedure. Such planning systems may provide for 3D- printed dental splints for use during surgery to guide the teeth toward the planned position. The user of such a software system must specify the relative position and orientation of the teeth of both jaws (i.e., the maxilla with respect to the mandible, or vice versa), or parts thereof, when the patient brings both jaws into contact to bite. The relative position and orientation of the teeth of both jaws when the patient brings both jaws into contact to bite is referred to as the patient's occlusion. In some orthognathics cases, the surgeon may need to perform additional osteotomies to split the maxilla and/or mandible into multiple parts. Each individual part is then repositioned in a slightly different way. This is referred to as a split mandible or a split maxilla. It may be required, e.g., if the maxilla or mandible is too small to support a proper occlusion or to obtain an acceptable functional or aesthetic outcome for the patient. Typically, the parts of one jaw are repositioned to be slightly further apart than they were before surgery. In such cases, the occlusion comprises the relative position and orientation of all jaw parts relative to the other jaw. If the planned intervention involves splitting both the maxilla and mandible, then the occlusion comprises the relative position and orientation of all jaw parts relative to one arbitrarily selected part in one of both jaws. In some orthognathics cases, the surgeon may decide that during or after orthognathic surgery, material is to be removed from the occlusal surface of one or more teeth by grinding or burring. This may be the case if, for example, parts of one or more teeth protrude from the rest of the teeth in the same jaw and thereby interfere with an appropriate occlusion. In such cases, burring down the protruding parts of those teeth may improve the patient's post-operative occlusion, by allowing the teeth of both jaws to make contact in different points. The occlusion is determined by an optical scan of dental cast models which the surgeon has physically placed in occlusion. Figure 1 depicts a conventional workflow to specify the occlusion for computer-assisted planning of orthognathic surgery. At step 2 of Figure 1, impression molds of the patient's maxilla and mandible are created. At step 4, plaster casts are created from the impression molds. At step 6, the two plaster casts are positioned together in an articulator to determine and represent the desired occlusion. At step 8, the plaster casts are secured together in the desired occlusion. At step 10, the fixed plaster casts are optically scanned for use in a computer-assisted planning system. In split maxilla or split mandible cases, step 4 in Figure 1 additionally involves physically cutting one or both plaster casts to simulate the additional osteotomies performed to split the corresponding jaw(s). The resulting parts of each cast are then fixed together in a different relative position and orientation, representing the desired new shape of the split jaw. However, in many cases, such "occlusion scans" may not be readily available. For example, the surgeon may prefer a fully digital workflow using intra-oral scans of the teeth instead of casts. As another example, the relative positioning of the casts (representing the desired occlusion) may be disturbed prior to optical scanning, such as during transport. In such cases, the surgeon would need to specify the occlusion through other means, such as by using a user interface integrated into the planning software to manually rotate and translate 3-D models of the jaws and/or jaw parts relative to one another until the desired occlusion is achieved. Figure 2 depicts an example all-virtual workflow to specify the occlusion for computer-assisted planning of orthognathic surgery. At step 22A, the plaster casts (created as described above in connection with steps 2 and 4 of Figure 1) are optically scanned. Alternatively, at step 22B, both jaws are optically scanned intra-orally. At step 24, the optical scans are provided to the planni