METHODS AND SYSTEMS FOR OBTAINING HINGE AXIS POSITION AND CONDYLE GUIDE INCLINATION FROM A PATIENT

Abstract

The present invention relates to methods and systems for generating a 3-D dental impression with a corresponding hinge axis position and, in certain embodiments, a condylar guide inclination. In some embodiments, an intraoral scanner and a computer processing system are employed to: i) generate upper and lower jaw models, and first and second occlusal 3-D models with different mouth openings (MOs) or functional positions (FPs), ii) align the models to generate a composite 3-D model, iii) calculate a hinge axis position from the composite 3-D model based on the difference in said MOs or FPs, and iv) mount the 3-D dental impression on a virtual articulator (VA) by aligning the hinge axis position to the hinge axis position of the VA.

Claims

1. A method of generating a hinge axis position 3-D impression comprising: a) generating from a subject: i) upper and lower jaw teeth and gum (UJTG and LJTG) 3-D models, and ii) first and second occlusal 3-D models with different mouth openings (MOs) or functional positions (FPs), b) aligning said UJTG and LJTG 3-D models and the first and second occlusal 3-D models to generate a composite 3-D model, c) calculating a first hinge axis position from the composite 3-D model based on the difference in said MOs or FPs, and d) generating a hinge axis position 3-D impression (HAP 3-D impression) by combining said first hinge axis position with said UJTG and LJTG 3-D models, wherein said UJTG and LJTG 3-D models are aligned to each other using said first or second occlusal 3-D model.

2. The method of claim 1, wherein said generating said UJTG and LJTG 3-D models, and first and second occlusal 3-D models, is performed using an intraoral scanner.

3. The method of claim 1, wherein said methods further comprises: e) mounting said HAP 3-D impression on a virtual articulator (VA) by aligning said first hinge axis position to the hinge axis position of the VA.

4. The method of claim 1, further comprising: obtaining a vertical distance from a chosen point on said HAP 3-D impression to an anterior reference point on said subject's face.

5. The method of claim 4, wherein said chosen point is an edge of an incisor of said subject.

6. The method of claim 4, further comprising the processing step(s) of: a) positioning said chosen point on said HAP 3-D impression said vertical distance from said VA horizontal upper arm, thereby horizontally mounting said HAP 3-D impression to said VA; and/or b) positioning the midpoint of said HAP 3-D impression to the mid-point of said VA, thereby vertically mounting said HAP 3-D impression on said VA.

7. The method of claim 6, wherein said VA comprises an incisal pin and/or incisal rod, and wherein said mid-point of said VA is defined by said incisal pin and/or said incisal rod.

8. The method of claim 6, wherein both a) and b) are conducted, thereby generating a VA with a fully-mounted 3-D impression.

9. The method of claim 1, further comprising: e) generating a protrusive occlusal 3-D model; f) adding said first hinge axis position to said UJTG 3-D model to generate a UJTG-hinge axis model with said first hinge axis position; g) adding said first hinge axis position to said LJTG 3-D model to generate a LJTG-hinge axis model with a second hinge axis position; h) aligning said UJTG-hinge axis model with said LJTG-hinge axis model using said protrusive 3-D model, thereby generating a protrusive hinge axis position impression (Pro HAP impression), wherein said Pro HAP impression comprises: A) said first hinge axis position, and B) said second hinge axis position which is at a different position than said first hinge axis position.

10. The method of claim 9, further comprising i) in the sagittal plane with respect to said Pro HAP impression, measuring an angle between said horizontal reference plane and a line connecting said first and second hinge axis positions, wherein said angle is a condylar guide inclination for said HAP impression when said HAP impression is fully mounted in said VA.

11. The method of any of claims 1-10, wherein only an intraoral scanner is used to take measurements of said subject's teeth and gums.

12. The method of any of claims 1-10, wherein none of the following are used: manual facial measurements, electronic facial scans, face/skull tomography, and face/skull radiography.

13. A method comprising: using an intraoral scanner and a processing system comprising a computer processor and non-transitory computer memory, for performing the steps of: a) obtaining a first 3-D model of the upper jaw teeth and gums (UJTGs), b) obtaining a second 3-D model of the lower jaw teeth and gums (LJTGs), c) obtaining a third 3-D model that comprises at least a portion of said UJTGs and LJTGs in an occlusal and centric relation (CR) or retruded relation (RR) at a first mouth opening (MO) or functional position (JM), d) obtaining a fourth 3-D optical scan that comprises at least a portion of said UJTGs and LJTGs in a CR or RR at a second mouth opening (MO) or FP that is different from said first MO, e) aligning said first, second, third, and fourth 3-D models to generate a composite aligned model; f) calculating a CR or RR hinge axis position based on the difference between said first MO or FP and said second MO or FP; and g) generating a CR or RR hinge axis position 3-D impression (CorR HAP impression) by combining: A) said CR or RR hinge axis position, said first 3-D model, and said second 3-D model, wherein said first 3D model and said second 3-D model are aligned to each other using said third 3-D model, or said fourth 3-D model.

14. A method of generating a hinge axis position 3-D impression comprising: a) performing the following on a subject using an intraoral scanner, wherein the subject has an upper jaw comprising teeth and gums (UJTGs) and a lower jaw comprising teeth and gums (LJTGs): i) a scan of the oral cavity of a subject to generate UJTGs scan data and LJTGs scan data; ii) a scan of said subject's UJTGs and LJTGs with said lower jaw and upper jaw in a first occlusive and centric relation (CR) or retruded relation (RR) to generate first CR or RR scan data, wherein said first occlusive CR or RR position has a first mouth opening (MO) or functional position (FP); and iii) a scan of said subject's UJTGs and LJTGs with said lower jaw and upper jaw in a second occlusive and centric relation (CR) or retruded relation (RR) to generate second CR or RR scan data, wherein second occlusive and CR or RR has a second MO or FP that is different from said first MO or FP, and b) implementing the following processing steps with a processing system that comprises: a computer processor and non-transitory computer memory comprising one or more computer programs for: i) generating 3-D models from intraoral scanner data, ii) aligning 3-D models, and iii) determining a hinge axis position: i) processing said scan data to generate corresponding 3-D models that comprise: a UJTG 3-D model, a LJTG 3-D model, a first CR or RR 3-D model, and a second CR or RR 3-D model, ii) aligning said UJTG 3-D model with said first and second CR or RR 3-D models to generate first and second aligned models respectively; iii) aligning said LJTG 3-D model with said first and second CR or RR 3-D model to generate a third and fourth aligned models respectively, iv) aligning said first, second, third, and fourth aligned models to generate a composite aligned model that comprises: A) a composite UJTG, B) a first composite LJTG with a first tooth, and C) a second composite LJTG with a second tooth which is the same tooth as said first tooth, but is located at a different vertical height with respect to said composite UJTG; v) processing said composite aligned model such that: i) a first reference point is assigned at or near the top of said first tooth (rp1) and said second tooth (rp2); and ii) a second reference point is assigned at or near the bottom of said first tooth (rp3) and said second tooth or in the gums below said first tooth and said second tooth (rp4), and vi) processing said rp1, rp2, rp3, and rp4 such that: A) the following steps are implemented: a) connecting said rp1 and rp3 to generate a first line segment, and connecting said rp2 and rp4 to generate a second line segment; b) a first plane perpendicular to said first line segment is generated that bisects said first line segment, c) a second plane perpendicular to said second line segment is generated, wherein said second plane bisects said second line segment and d) determining a crossing line where said first and second planes intersect, and/or B) the x, y, z coordinates of said first and second lines, said first and second planes, and said crossing line are all calculated mathematically by one or more algorithms, and wherein said crossing line is a CR or RR hinge axis position, and vii) generating a CR or RR hinge axis position 3-D impression (CorR HAP impression) by combining said CR or RR hinge axis position, said UJTG 3-D model, and said LJTG 3-D model, wherein said UJTG-3D model and said LJTG 3-D model aligned to each other using said first CR or RR 3-D model, or said second CR or RR 3-D model.

15. The method of claim 14, wherein said one or more computer programs further provides a virtual articulator (VA) comprising a VA hinge axis and a VA horizontal upper arm, and wherein the method further comprises the processing step of aligning said CR or RR hinge axis of said 3-D impression with said VA hinge axis, thereby axially mounting said 3-D impression to said VA.

16. The method of claim 15, further comprising: obtaining a vertical distance from a chosen point on said 3-D impression to a horizontal reference plane on said subject's face above the nostrils but below the eyes.

17. The method of claim 16, wherein said chosen point is an edge of an incisor of said subject.

18. The method of claim 16, further comprising the processing step(s) of: a) positioning said chosen point on said 3-D impression said vertical distance from said VA horizontal upper arm, thereby horizontally mounting said 3-D impression to said VA; and/or b) positioning the anatomic midpoint of said 3-D impression to the mid-point of said VA, thereby vertically mounting said 3-D impression on said VA.

19. The method of claim 18, wherein said VA comprises an incisal pin and/or incisal rod, and wherein said mid-point of said VA is defined by said incisal pin and/or said incisal rod.

20. The method of claim 18, wherein both a) and b) are conducted, thereby generating a VA with a fully-mounted 3-D impression.

21. The method of claim 20, further comprising: a) scanning said subject's UJTGs with hinge and LJTGs using an intraoral scanner with said lower jaw and upper jaw in an occlusive and protrusive position to generate protrusive scan data; b) conducting the following processing steps with said processing system: i) processing said protrusive scan data to generate a protrusive 3-D model; ii) adding said CR or RR hinge axis position to said UJTG-3D model to generate an UJTG hinge axis model with a first hinge axis position, iii) adding said CR or RR hinge axis position to said LJTG-3D model to generate a LJTG hinge axis model with a second hinge axis position, and iv) aligning said UJTG hinge axis model with said LJTG hinge axis model using said protrusive 3-D model, thereby generating a protrusive hinge axis position impression (Pro HAP impression), wherein said Pro HAP impression comprises: A) said first hinge axis position which is at the same location as said CR or RR hinge axis position, and B) said second hinge axis position which is at a different position than said first hinge axis.

22. The method of claim 21, wherein said one or more computer programs further provides a condylar guide inclination measuring component, and wherein the method further comprises conducting the following processing step with said processing system: in the sagittal plane with respect to said Pro HAP impression, measuring an angle between said horizontal reference plane and line connecting said first and second hinge axis positions, wherein said angle is a condylar guide inclination for said CorR HAP impression when said CoR HAP impression is fully mounted in said VA.

23. The method of any of claims 14-22, wherein only an intraoral scanner is used to take measurements of said subjects teeth and gums.

24. The method of any of claims 14-22, wherein none of the following are used: manual facial measurements, electronic facial scans, face/skull tomography, and face/skull radiography.

25. A system for generating a hinge axis position 3-D impression comprising: a) non-transitory computer memory comprising one or more computer programs for: i) align 3-D models, and ii) determine a hinge axis position, wherein said one or more computer programs, in conjunction with a computer processor, is/are configured to: i) process: A) UJTGs scan data, B) LJTGs scan data, C) first centric relation (CR) or retruded relation (RR) scan data having a first mouth opening (MO) or functional position (FP), and D) second centric relation (CR) or retruded relation (RR) scan data having a first mouth opening (MO) or functional position (FP), thereby generating: corresponding 3-D models that comprise: A) a UJTG 3-D model, B) a LJTG 3-D model, C) a first CR or RR 3-D model, and a D) second CR or RR 3-D model; ii) align said UJTG 3-D model with said first and second CR or RR 3-D models to generate first and second aligned models respectively; iii) align said LJTG 3-D model with said first and second CR or RR 3-D model to generate a third and fourth aligned models respectively, iv) align said first, second, third, and fourth aligned models to generate a composite aligned model that comprises: A) a composite UJTG, B) a first composite LJTG with a first tooth, and C) a second composite LJTG with a second tooth which is the same tooth as said first tooth, but is located at a different vertical height with respect to said composite UJTG; v) process said composite aligned model such that: i) a first reference point is assigned at or near the top of said first tooth (rp1) and said second tooth (rp2); and ii) a second reference point is assigned at or near the bottom of said first tooth (rp3) and said second tooth or in the gums below said first tooth and said second tooth (rp4), and vi) process said rp1, rp2, rp3, and rp4 such that: A) the following steps are implemented: a) connecting said rp1 and rp3 to generate a first line segment, and connecting said rp2 and rp4 to generate a second line segment; b) a first plane perpendicular to said first line is generated, c) a second plane perpendicular to said second line segment is generated, wherein said second plane bisects said second line segment; and d) determine a crossing line where said first and second planes cross, and/or B) the x, y, z coordinates of said first and second lines, said first and second planes, and said crossing line are all calculated mathematically by one or more algorithms, and wherein said crossing line is a CR or RR hinge axis position, and vii) generating a CR or RR hinge axis position 3-D impression (CorR HAP impression) by combining said C or R hinge axis position, said UJTG 3-D model, and said LJTG 3-D model, wherein said UJTG-3D model and said LJTG 3-D model aligned to each other using said first CR or RR 3-D model, or said second CR or RR 3-D model.

26. The system of claim 25, further comprising: b) said computer processor.

27. The system of claim 25, wherein said one or more computer programs further provides a virtual articulator (VA) comprising a VA hinge axis and a VA horizontal upper arm, and wherein said one or more computer programs are further configured to align said CR or RR hinge axis of said 3-D impression with said VA hinge axis, thereby axially mounting said 3-D impression to said VA.

28. The system of claim 25, wherein said one or more computer programs are further configured to receive a vertical distance from a chosen point on said 3-D impression to a horizontal reference plane on said subject's face above the nostrils but below the eyes.

29. The system of claim 28, wherein said chosen point is an edge of an incisor of said subject.

30. The system of claim 28, wherein said one or more computer programs are further configured to: a) position said chosen point on said 3-D impression said vertical distance from said VA horizontal upper arm, thereby horizontally mounting said 3-D impression to said VA; and/or b) position the anatomic midpoint of said 3-D impression to the mid-point of said VA, thereby vertically mounting said 3-D impression on said VA.

31. The system of claim 30, wherein said VA comprises an incisal pin and/or incisal rod, and wherein said mid-point of said VA is defined by said incisal pin and/or said incisal rod.

32. The system of claim 30, wherein both a) and b) are conducted, thereby generating a VA with a fully-mounted 3-D impression.

33. The system of claim 32, wherein said one or more computer programs are further configured to: i) process protrusive scan data to generate a protrusive 3-D model; ii) add said CR or RR hinge axis position to said UJTG-3D model to generate an UJTG hinge axis model with a first hinge axis position, iii) add said CR or RR hinge axis position to said LJTG-3D model to generate a LJTG hinge axis model with a second hinge axis position, and iv) align said UJTG hinge axis model with said LJTG hinge axis model using said protrusive 3-D model, thereby generating a protrusive hinge axis position impression (Pro HAP impression), wherein said Pro HAP impression comprises: A) said first hinge axis position which is at the same location as said CR or RR hinge axis position, and B) said second hinge axis position which is at a different position than said first hinge axis.

34. The system of claim 32, wherein said one or more computer programs further provides a condylar guide inclination measuring component which is configured to conduct the following processing step: in the sagittal plane with respect to said Pro HAP impression, measure an angle between said horizontal reference plane and line connecting said first and second hinge axis positions, wherein said angle is a condylar guide inclination for said CorR HAP impression when said CoR HAP impression is fully mounted in said VA.

35. The system of any of claims 25-34, wherein scan data is only provided from an intraoral scanner.

36. The system of any of claims 25-34, wherein none of the following are used to generate scan data: manual facial measurements, electronic facial scans, face/skull tomography, and face/skull radiography.

Description

DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 shows 3-D models constructed from optical scans of jaws and occlusion. FIG. 1A shows an exemplary upper teeth and gums 3-model. FIG. 1B shows an exemplary upper teeth and gums 3-D model. FIG. 1C shows an exemplary occlusal and centric scan 3-D model. FIG. 1D shows an exemplary occlusal and centric 3-D model at a different MO than FIG. 1C. FIG. 1E shows an exemplary occlusal and protrusive 3-D model.

[0035] FIG. 2 shows an alignment (superimposition) of 3D models to generate a composite 3-D model.

[0036] FIG. 3 shows exemplary point markers on lower jaw scans.

[0037] FIG. 4 shows a virtual kinematic face bow.

[0038] FIG. 5 shows an alignment of VKF to . FIG. 5A shows a frontal view, and FIG. 5B shows a side view.

[0039] FIG. 6 shows exemplary steps for locating a hinge axis.

[0040] FIG. 7 shows an exemplary schematic of aligning a model to virtual articulator.

[0041] FIG. 8a shows an exemplary distance from incisor edge to horizontal reference plane (DIH) on a subject's face between the eyes and nostrils. FIG. 8B shows an exemplary methods to adjust the vertical position of model.

[0042] FIG. 9 shows superimposing upper and lower jaw models according to protrusion bite scan.

[0043] FIG. 10 shows an exemplary method for measuring condylar guide inclination.

[0044] FIG. 11 shows sagittal planes that crossing left and right temporomandibular joints of virtual articular (VA).

DETAILED DESCRIPTION OF THE INVENTION

[0045] The present invention relates to methods and systems for generating a 3-D dental impression with a corresponding hinge axis position and, in certain embodiments, a condylar guide inclination. In some embodiments, an intraoral scanner and a computer processing system are employed to: i) generate upper and lower jaw models, and first and second occlusal 3-D models with different mouth opening (MOs) or functional positions (FPs), ii) align the models to generate a composite 3-D model, iii) calculate a hinge axis position from the composite 3-D model based on the difference in said MOs or FPs, and iv) mount the 3-D dental impression on a virtual articulator (VA) by aligning the hinge axis position to the hinge axis position of the VA.

[0046] The dental articulator is a device to simulate the occlusion of a patient, which is a fundamental tool for dental treatment. The virtual articulator is a digital counterpart of a real (manual) dental articulator. To accurately reproduce the position and movement of the jaw, the occlusal relationship should be recorded from the patient and transferred to the articulator, and this procedure is called mounting an articulator. At present, available methods of mounting a virtual articulator have to rely on conventional mounting approach or face scan. The methods and systems described herein allow a virtual articulator to be mounted (e.g., using only data from an intraoral scanner).

[0047] The following provides an exemplary description of how to determine a hinge axis, mount a virtual articulator, and find the condylar guide inclination (e.g., only using intraoral scanner data).

[0048] I. Initial Intraoral Device Scans and Model Generation

[0049] First, one obtains optical scans of jaws and occlusion using an intraoral scanner. Optical scans of an upper jaw (with teeth and gums; UJTG) are scanned (model shown in FIG. 1A) and lower jaw (with teeth and gums; LJTG) are scanned (model shown in FIG. 1B). A patient's jaw is positioned into centric relation (CR), and one applies bite registration material to record the CR. Scan both maxillary and mandibular jaws to get the first occlusion scan (OSCR1), as shown in FIG. 1C. Use bite registration material to record another CR with a varied mouth opening (MO). Scan both maxillary and mandibular jaws to obtain the second occlusion scan (OSCR2), as shown in FIG. 1D. Next, put the lower jaw into protrusion position, apply bite registration material, and scan both maxillary and mandibular jaws to get the third occlusion scan (OSP), as shown in FIG. 1E. These scans are converted into digital three-dimensional models as shown in FIG. 1. It is noted that Retruded Relation (RR) can used as an alternative to centric relation.

[0050] II. Obtain Distance from Reference Point to Horizontal Reference Plane

[0051] Next, obtain a vertical distance from a point on a tooth or gums (e.g., central incisor edge) to horizontal reference plane. This step can be done by using a ruler when the patient is smiling as shown in FIG. 8a.

[0052] III. Aligning/Superimposing Scans and Adding Reference Points

[0053] Next, align OS.sub.CR1 3-D model and OS.sub.CR2 3-Model to UJTGs model by matching the anatomic structures of upper jaw. Then align LJTGs model to OS.sub.1 3-D model by matching the anatomic structures of lower jaw. Align a duplication of LJTG to OS.sub.2 3-D model. The firstly aligned lower jaw model is LJL1TGs, the other one is LJ.sub.2 TGs; see FIG. 2. It is noted that part II. above can be omitted if OS1 and OS2 can provide enough anatomic landmarks of lower jaw for locating the hinge axis.

[0054] Next, choose a landmark on the 3D model of LJ.sub.1TG, add a point marker (A.sub.1) on it. Add another maker on the same position of LJ.sub.2TG. Choose another landmark on LJ.sub.1TG and LJ.sub.2TG, add other two corresponding point markers (B.sub.1, B.sub.2) (see FIG. 3). From A.sub.1, A.sub.2, B.sub.1, and B.sub.2, the 3D position of hinge axis can be located.

[0055] IV. Locating the Hinge Axis

[0056] There are two general approaches to locate hinge axis: 1) manual approach, and 2) automatic (algorithm) approach.

[0057] A. Acquiring Position of Hinge Axis Manually

[0058] In work conducted during the development of embodiments herein a tool named virtual kinematic facebow (VKF) was constructed to locate hinge axis manually. The VKF has a plane and a probe. The probe is perpendicular to the plane and has scales on each side (see FIG. 4. Align the probe to , keep the VKF plane as the perpendicular bisector of (see FIG. 5). Make a duplicate of VKF, align it to . Plane A is the perpendicular bisector of and plane B is the perpendicular bisector of . Given that in CR, the lower draw rotates around the transverse horizontal axis, the hinges axis can be found as the intersection of plane A and plan B (FIG. 6).

[0059] B. Acquiring Position of Hinge Axis Automatically (Algorithm)

[0060] Acquire the 3-dimensional spatial coordinate of A.sub.1 (x.sub.a,y.sub.a1,z.sub.a1), A.sub.2 (x.sub.a,y.sub.a2,z.sub.a2), B1 (x.sub.b1,y.sub.b1,z.sub.b1), and B2 (x.sub.b2,y.sub.b2,z.sub.b2). The 3-dimensional spatial expression of the hinge axis can be defined as follows:

Midpoint between A.sub.1(x.sub.a1,y.sub.a1,z.sub.a1), A.sub.2(x.sub.a2,y.sub.a2,z.sub.a2):

[00001]$A_m\left(\frac{x_{a1}+x_{a2}}{2},\frac{y_{a1}+y_{a2}}{2},\frac{z_{a1}+z_{a2}}{2}\right)$

The vector that connects A.sub.1 and A.sub.2 is:

=(x.sub.a2−x.sub.a1,y.sub.a2−y.sub.a1,z.sub.a2−z.sub.a1)=(a,b,c)

The perpendicular bisector follows this equation:

ax+by+cz=d

To solve for d, plug A.sub.m into the above equation:

[00002]$d=\frac{\left(x_{a1}+x_{a2}\right).Math.\left(x_{a2}-x_{a1}\right)}{2}+\frac{\left(y_{a1}+y_{a2}\right).Math.\left(y_{a2}-y_{a1}\right)}{2}+\frac{\left(z_{a1}+z_{a2}\right).Math.\left(z_{a2}-z_{a1}\right)}{2}$$d=\frac{x_{a2}^2-x_{a1}^2}{2}+\frac{y_{a2}^2-y_{a1}^2}{2}+\frac{z_{a2}^2-z_{a1}^2}{2}$

The perpendicular bisector for points B.sub.1 and B.sub.2 can be derived similarly
Given two planes a.sub.1x+b.sub.1y+c.sub.1z=d.sub.1 and a.sub.2x+b.sub.2y+c.sub.2z=d.sub.2,
The vector is parallel to the intersect of the two planes:

v=(a.sub.1,b.sub.1,c.sub.1)×(a.sub.2,b.sub.2,c.sub.2)=(b.sub.1c.sub.2−c.sub.1b.sub.2,c.sub.1a.sub.2−a.sub.1c.sub.2,a.sub.1b.sub.2−b.sub.1a.sub.2)=(l,m,n)

Find an arbitrary point on the intersect:

[00003]$\mathrm{plug}z=0\mathrm{into}{a}_{1}x+b_{1}y+c_{1}z=d_1\mathrm{and}{a}_{2}x+b_{2}y+c_{2}z=d_2;\mathrm{and}\mathrm{then}\mathrm{solve}\mathrm{for}x=x_0\mathrm{and}y=y_0;$$\mathrm{Then}$$\left[\begin{array}{c}{x}_0\\ y_0\\ 0\end{array}\right]+t\left[\begin{array}{c}l\\ m\\ n\end{array}\right],t\in ℝ\mathrm{is}\mathrm{the}\mathrm{expression}\mathrm{for}\mathrm{the}\mathrm{intersect}\left(\mathrm{hinge}\mathrm{axis}\right)$

According to above expression, the 3D position of hinge axis can be calculated by computer.

[0061] V. Mount 3D Jaw Models on Virtual Articulator (VA)

[0062] Alinge the models to the VA by matching the hinge axis of models to that of VA (see FIG. 7). Rotate model around hinge axis, until the distance from model incisors to the upper arm of VA equals to distance (e.g., DIH) which is obtained as described above (see FIG. 8a). Next, align the midline of the model to VA, which will put the jaw models in the right position.

[0063] VI. Acquiring Left and Right Condylar Guide Inclinations

[0064] Create a lower jaw model with hinge axis, align it to upper jaw model by matching OS.sub.P(FIG. 9). Now, the hinge axis attached to the lower jaw is in a protrusion position. The condylar guide inclination can be measured in a sagittal plane (see FIGS. 10 and 11), as the angle between horizontal reference plane and the line passing hinge axis in CR and hinge axis in protrusion. Left and right condylar guide inclination should be measured in according sagittal plane that cross left and right temporomandibular joints of VA (see FIG. 11).

REFERENCES

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[0077] All publications and patents mentioned in the above specification are herein incorporated by reference. Various modifications and variations of the described compositions and methods of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention that are obvious to those skilled in the relevant fields are intended to be within the scope of the present invention.