CN114431989B - Method for establishing coordinate system based on target dental arch curve, automatic tooth arrangement method and tooth movement evaluation method - Google Patents

Abstract

The invention relates to a method for establishing a coordinate system based on a target dental arch curve, and an automatic tooth arrangement method and a tooth movement evaluation method are established based on the dental arch curve coordinate system. The coordinate system of the dental arch curve has different local coordinate systems composed of tangent axis, main normal axis and subnormal axis at different points of the curve, which adapt to the three-dimensional position of the teeth and can guide more efficient and accurate automatic tooth arrangement and more Clinical evaluation of tooth movement is helpful for more scientific, reasonable and accurate design of tooth movement plan and evaluation of curative effect.

Description

Establishment method of coordinate system based on target dental arch curve, automatic tooth arrangement method and tooth movement evaluation method

technical field

The invention belongs to the technical field of dental orthodontics, and in particular relates to a method for establishing a coordinate system based on a target dental arch curve, an automatic tooth arrangement method and a tooth movement evaluation method based on the dental arch curve coordinate system.

technical background

Nowadays, orthodontic treatment has entered the digital era. Whether it is digital fixed orthodontics or digital invisible orthodontic technology without brackets, it is necessary to digitally arrange teeth based on the digital dental model before treatment, arrange the target dental model, and carry out the process from the initial Evaluation of tooth movement to target position. The establishment of efficient and accurate automatic tooth arrangement and scientific and accurate tooth movement evaluation method is of great significance for the design of treatment goals, the construction of treatment mechanics system and the evaluation of curative effect.

At present, the mainstream orthodontic tooth arrangement software still relies on technicians to manually arrange teeth, and the efficiency of tooth arrangement is low. In recent years, methods for automatically aligning teeth have been gradually proposed (for example, see Patent Documents 1 and 2 below). In the automatic tooth arrangement method, it is necessary to establish the dental arch curve, the global coordinate system and the tooth local coordinate system, and then arrange the teeth through the calculation of the coordinate system. However, in the above automatic tooth arrangement method, the established coordinate system is still the traditional flute. Carl's coordinate system (rectangular coordinate system), the calculation of each angle when arranging teeth depends on specific experience values.

For the evaluation of tooth movement, simplified mathematical models were usually used in the past. A common method is to use the jawbone as a reference to establish a global rectangular coordinate system in the three-dimensional position space to determine the sagittal, coronal and coronal directions of each tooth before and after treatment. The amount and direction of movement in the vertical direction. This method assigns the same sagittal, coronal, and vertical orientations to all teeth, however, this does not correspond to the fact that teeth are arranged in a circular arch shape with individualized positions, angles, and directions of movement. Another common method is to establish a local reference coordinate system with a single tooth before treatment, and evaluate the movement amount and direction of a single tooth along its own long axis (or the tangent to its own long axis) (for example, see below Patent Document 3). Although this method has a personalized tooth movement direction, it is affected by the misalignment of the teeth before treatment. The state has a great influence, and the error The tooth movement direction pointed by the local coordinate system established by the position along its own long axis is not the same as the clinically realistic movement direction pointed by the normally arranged teeth. Therefore, the above two methods for evaluating tooth movement are not suitable for clinical practice, and only have mathematical significance, which cannot evaluate tooth movement scientifically and accurately. Considering that the essence of orthodontic tooth movement is the reconstruction of the alveolar bone guided by mechanical force, a tooth movement evaluation method based on the curved natural coordinate system of the alveolar bone shape was proposed (for example, refer to the following patent document 4), which The method endows teeth with individualized biomechanical movement evaluation, but requires individualized or big data mean CBCT alveolar bone data.

It should also be noted that although the tooth movement measurement method is mentioned in the prior art (for example, refer to the following patent documents 5 and 6), the focus is on using CBCT images and/or three-dimensional planes to indirectly obtain the complete crown before and after treatment. The superposition of the tooth model of the root, and then calculate the amount of movement of the teeth before and after treatment, and the mathematical calculation of the amount of tooth movement itself is still based on the traditional Cartesian coordinate system.

current technology

Patent Document 1: CN107374758A

Patent Document 2: CN108403234A

Patent Document 3: CN108245264A

Patent Document 4: CN113827362A

Patent Document 5: CN110811653A

Patent Document 6: CN111388125A

Contents of the invention

The problem to be solved by the invention

According to the technology recorded in Patent Documents 1 and 2, the teeth are automatically aligned on the dental arch curve through the calculation between the local Cartesian coordinate system and the global Cartesian coordinate system, and the calculation values of the angles of each dimension refer to a fixed empirical value or theory value, the tooth angle cannot adapt to the personalized dental arch curve shape, or simply point the long axis of the tooth to the vertical axis of the global coordinate system. The teeth after automatic alignment are still insufficient in accuracy, and more may be needed in the later stage. manual fine-tuning.

According to the technology described in Patent Document 4, a curved natural coordinate system based on the alveolar arch curve is established, and the tooth movement is measured in the curved natural coordinate system. This method can reflect the biomechanical movement of the tooth more scientifically and accurately, but it needs The patient's CBCT data is not universal for medical units without CBCT equipment at the grassroots level. Although big data mean CBCT data can be used to replace it, the accuracy will still be lower than individualized real CBCT data. In addition, for automatic tooth arrangement, the coordinate system based on the alveolar arch curve is not as good as the coordinate system based on the dental arch curve, because the dental arch curve is fitted based on the feature points of the crown, which can more accurately guide the neat arrangement of the crown.

Aiming at the problems existing in the prior art, the inventors of the present application realized that a better coordinate system is needed, since it is more efficient and accurate for automatic tooth arrangement, it can also evaluate the tooth movement more reasonably and accurately, and has a greater universality. After research, a method for establishing the natural coordinate system of the curve based on the target dental arch curve was found, and based on the coordinate system of the dental arch curve, computer automatic tooth arrangement and tooth movement evaluation were performed.

The first aspect of the present application provides a method for establishing a coordinate system based on the target dental arch curve, which sequentially includes the following steps:

Obtain the target dental arch curve based on the tooth arrangement before treatment or the big data dental arch curve;

The curve natural coordinate system is established based on the target dental arch curve.

In some embodiments, the specific method of obtaining the target dental arch curve based on the tooth arrangement before treatment or the big data dental arch curve is:

(1) Obtain the digital dental model before treatment, select the tooth feature points on the upper jaw model and the lower jaw model respectively, and use mathematical methods to fit the upper jaw dental arch curve and the lower jaw dental arch curve respectively,

Among them, the characteristic points of the teeth are the midpoints of the incisal margins of the central incisors and lateral incisors, the cusps of the canines, the buccal cusps of the first premolars and the second premolars, and the mesiobuccal cusps of the first and second molars and the distal buccal point, it can also be the coronal axis point, the geometric center point of the crown, the contact point of the proximal surface or the functional point of the cusp;

The fitted dental arch curves have different shapes in the three-dimensional direction. On the horizontal plane, the dental arch curves are roughly divided into pointed circular, oval, square circular and individualized arch shapes. On the sagittal plane, the dental arch curves are Spee curved shape, on the coronal plane, the dental arch curve is in the Wilson curved shape; or,

Obtain the maxillary arch curve and the mandibular arch curve according to the dental arch curve fitted by the big data dentition, select the appropriate shape of the dental arch curve in the big data, and determine the width, length and depth of the dental arch curve according to the width, length and depth of the dental arch before treatment. length and depth;

(2) Automatically match the curves of the upper and lower dental arches, so that the curves of the upper and lower dental arches have uniform and normal coverage on the horizontal plane;

(3) Physicians or technicians can adjust the width, length, depth, shape of the dental arch curve and the matching degree of the upper and lower dental arch curves according to the treatment needs, and finally generate the target dental arch curve.

In some embodiments, the step of establishing the natural coordinate system of the curve based on the target dental arch curve is:

(1) Select the midpoint on the target dental arch curve as the origin of the coordinate system, start from the origin of the coordinate system, and determine the corresponding reference points and spacing of each tooth position on the dental arch curve in turn according to the width of the patient's teeth;

(2) For any point on the dental arch curve, the tangent of the curve at this point is taken as the tangent axis of the local coordinate system, and the plane perpendicular to the tangent axis is the normal plane;

(3) Determine the subnormal axis of the local coordinate system on the normal plane where the reference point corresponding to each tooth position is located. The method is: compare each tooth position to The standard reference values of crown axis inclination and crown inclination of the plane are transformed into the angle data of the tooth long axis relative to the dental arch curve, or according to the normal after treatment Dental model or untreated normal The big data of the dental model obtains the angle data of the long axis of each tooth relative to the dental arch curve, and the projection line of the long axis of the tooth on the normal plane is determined as the subnormal axis;

Physicians can adjust the subnormal axis of each tooth position reference point according to the needs of the patient's treatment plan;

For the points between the reference points of two teeth on the dental arch curve, use interpolation method or other mathematical methods to obtain the subnormal axis corresponding to each point;

(4) The tangent axis and subnormal axis of each point constitute the subtangent plane of the local coordinate system of the dental arch curve, the perpendicular line from the tangent plane is the main normal axis, and the tangent axis and the main normal axis form a close plane, and the main normal axis constitutes a normal plane with the subnormal axis;

Finally, the natural coordinate system of the dental arch curve with different local coordinate systems consisting of tangent axis, subnormal axis, principal normal axis, occult plane, secondary tangent plane and normal plane is established at different points of the three-dimensional dental arch curve.

The second aspect of the present application provides an automatic tooth alignment method, which uses the above method of establishing a coordinate system based on the target dental arch curve to automatically align teeth.

In some embodiments, the specific method for automatically aligning teeth based on the target dental arch curve coordinate system is:

According to the method described in the first aspect of the present application, the target dental arch curve is obtained and the natural coordinate system of the curve is established;

Select the tooth feature points consistent with the tooth feature points of the fitted dental arch curve;

Determine the tooth long axis and tooth transverse axis of the tooth;

The midpoint of the characteristic points of the central incisors on both sides coincides with the midpoint of the dental arch curve, and the teeth are moved in sequence so that the characteristic points of the teeth coincide with the dental arch curve;

Check the adjacent collision, move the tooth along the dental arch curve, make the adjacent point of the tooth contact without gap or collision, or keep a small amount of adjacent surface collision or a small amount of distance between the adjacent surfaces according to the requirements of the medical plan to deglaze the adjacent surface or reserve a gap;

Rotate the tooth around the subnormal axis of the local curvilinear coordinate system of the tooth, so that the angle between the transverse axis of the tooth and the tangent axis of the curvilinear coordinate system on the close plane of the curvilinear coordinate system is 0, thereby positioning the crown torsion of the tooth;

Rotate the tooth around the tangent axis of the local curved coordinate system of the tooth, so that the angle between the long axis of the tooth and the subnormal axis of the curved coordinate system on the normal plane of the curved coordinate system is 0, so as to locate the crown tilt of the tooth, that is, the crown torque;

Rotate the tooth around the principal normal axis of the tooth’s local curvilinear coordinate system, so that the tooth’s long axis and the subnormal axis of the curvilinear coordinate system reach a certain standard value on the secondary tangent plane of the curvilinear coordinate system, thereby positioning the crown axis of the tooth. The value is changed from the existing relative The standard value of coronal inclination of the plane is converted or obtained from the coronal inclination value of the relative curvilinear coordinate system measured by big data;

Check the coverage between the upper and lower dentition, each tooth moves along the buccal and lingual direction along the main normal axis of the local coordinate system, so that the upper and lower dentition can reach the standard coverage, or according to the personalized coverage required by the medical plan;

To check the collision of opposing jaws, each tooth moves up and down along the subnormal axis of the local coordinate system, so that there is light or no contact between the upper and lower jaws, or local heavy contact is retained according to the medical protocol;

In order to obtain a better occlusal and adjacent relationship, the angles of the teeth can also be adjusted appropriately;

Check the adjacent collision again. If the tooth needs to move along the arch curve, reposition the crown torsion, crown axis tilt and crown tilt of the tooth after the movement, check the coverage, check the collision of the opposing jaw, and iteratively move and rotate the tooth until it reaches Reasonable tooth arrangement to complete automatic tooth arrangement;

The ideal occlusion parameters can generate a new coordinate system template.

The third aspect of the present application provides a tooth movement evaluation method, which uses the above method of establishing a coordinate system based on the target dental arch curve to perform tooth movement evaluation.

In some embodiments, the specific method for evaluating tooth movement based on the target dental arch curve coordinate system is:

According to the method described in the first aspect of the present application, the target dental arch curve is obtained and the natural coordinate system of the curve is established;

According to the method described in the second aspect of the present application, the teeth are automatically aligned, and the technician or physician can manually adjust the results of the automatic tooth alignment according to the treatment needs to obtain the final target tooth alignment;

Calculate tooth coordinates;

Calculate tooth movement changes;

Output tooth coordinates and tooth movement changes.

In some embodiments, the step of calculating tooth coordinates is:

(1) Define the direction of the coordinate system:

In the natural coordinate system of the dental arch curve, the tangent axis of the curve is the near-distal direction of the tooth, the main normal axis is the lip (buccal) lingual (palatal) direction of the tooth, and the secondary normal axis is the vertical direction of the tooth;

In the natural coordinate system of the dental arch curve, the normal plane of the curve is the lip (buccal) lingual (palatal) plane of the tooth, the tangent plane of the curve is the near-distal plane of the tooth, and the close plane of the curve is the horizontal plane of the tooth ;

(2) Calculate the coordinates of the teeth, including three-dimensional position and three-dimensional angle:

Locate the corresponding point of the tooth measurement point on the dental arch curve, which is the vertical point of the tooth measurement point on the dental arch curve, and the local coordinate system established on the corresponding point of the dental arch curve is the local coordinate system of the tooth;

The mesio-distal coordinates refer to the tooth position on the tangent axis, that is, the curve distance between the corresponding point of the tooth measurement point on the alveolar arch curve and the origin of the curve coordinate system;

The labial (cheek) lingual (palatal) coordinates refer to the tooth position on the main normal axis, that is, the straight-line distance between the vertical point of the tooth measurement point on the main normal axis and the corresponding point on the alveolar arch curve;

The vertical coordinate refers to the position of the tooth on the subnormal axis, that is, the straight-line distance between the vertical point of the tooth measurement point on the subnormal axis and the corresponding point on the alveolar arch curve;

Torsion angle refers to the angle between the tooth transverse axis and the curve tangent axis in the close plane;

Axial inclination refers to the angle between the long axis of the tooth and the subnormal axis of the curve in the tangential plane;

The inclination angle refers to the angle between the long axis of the tooth and the subnormal axis of the curve in the normal plane;

Calculate the tooth coordinates of the initial position and the target position, and also calculate the tooth coordinates of the intermediate stage.

In some embodiments, the step of calculating the change in tooth movement is:

The tooth movement change is equal to the difference between the tooth coordinates of the initial position and the tooth position of the target position, including three-dimensional displacement and three-dimensional angle change;

It is also possible to calculate the difference between the initial tooth coordinates and the tooth coordinates at any stage, and evaluate the change of tooth movement during the stage;

The mesio-distal movement refers to the movement of the teeth along the tangent axis, that is, the change of the mesio-distal coordinates of the teeth. Among them, the movement close to the midpoint of the curve is the mesial movement, and the movement away from the midpoint of the curve is the distal movement;

The lip (cheek) lingual (palatal) movement refers to the movement of the teeth along the main normal axis, that is, the change of the tooth lip (buccal) lingual (palatal) coordinates. The lip (cheek) movement refers to the outward movement, and the tongue ( Palate) to move means to move inward;

Elongation and depression refer to the movement of the teeth along the subnormal axis, that is, the change of the vertical coordinates of the teeth. Among them, the downward movement of the upper jaw is elongation, and the upward movement is depression, and vice versa for the lower jaw;

Torsion refers to the change of twist angle on the close plane;

Axial inclination refers to the change of axial inclination on the tangent plane;

Tilt is the change in the tilt angle in the normal plane.

In some embodiments, the measurement points for evaluating the amount of tooth movement include a cusp point or a midpoint of an incisal margin, a crown center point, a root center point, a tooth impedance center point, and a root point.

The beneficial effect of the present invention is that: the natural coordinate system of the curve based on the target dental arch curve can be used for automatic tooth arrangement and tooth movement evaluation at the same time, and the coordinate system is more efficient and accurate than the existing automatic tooth arrangement method at least in terms of tooth torsion arrangement , is superior to the coordinate system established based on the initial teeth in the prior art in terms of clinical significance of tooth movement evaluation, and superior to the coordinate system based on the alveolar arch curve in terms of universality, thus contributing to a more scientific, reasonable and efficient Accurate tooth movement program design and curative effect evaluation.

Description of drawings

Fig. 1 is a three-dimensional view of a dental arch curve fitted based on a cusp point and an incisal point in an embodiment of the present invention.

Fig. 2 is a side view of a dental arch curve based on tooth coronal axis point fitting in an embodiment of the present invention.

Fig. 3 is a top view of a dental arch curve fitted based on tooth adjoining points in an embodiment of the present invention.

Fig. 4 is a three-dimensional view of the dental arch curve coordinate system in one embodiment of the present invention.

Fig. 5 is a top view of automatic tooth arrangement based on the dental arch curve coordinate system in an embodiment of the present invention.

Fig. 6 is a side view of automatic tooth arrangement based on the dental arch curve coordinate system in an embodiment of the present invention.

Figure 7 is a schematic diagram of tooth measurement points in one embodiment of the present invention.

Fig. 8 is a schematic diagram of evaluating changes in tooth torsion angles in a dental arch curve coordinate system according to an embodiment of the present invention.

Fig. 9 is a schematic diagram of evaluating changes in inclination angles of tooth axes under the dental arch curve coordinate system according to an embodiment of the present invention.

Fig. 10 is a schematic diagram of evaluating changes in the inclination angle of teeth under the dental arch curve coordinate system in an embodiment of the present invention.

Mark 1: midpoint of incisal edge of tooth; Mark 2: cusp point; Mark 3: dental arch curve; Mark 4: tooth coronal axis point; Mark 5: tooth adjacent point; Mark 6: tangent axis of curve natural coordinate system; Mark 7: the principal normal axis of the natural coordinate system of the curve; Mark 8: the subnormal axis of the natural coordinate system of the curve; Mark 9: the transverse axis of the tooth; Mark 10: the long axis of the tooth; Mark 11: the center point of the crown; Mark 12: the tooth Impedance center point; mark 13: root center point; mark 14: apex point; mark 15: mesial-distal displacement of the tooth from point A to point B, which is the arc length of the curve between point A' and point B'; Mark 16: The buccal-lingual displacement of the tooth moving from point A to point B, the difference between the line distance between point A' and point B' on the main normal axis; mark 17: torsion angle, on the close plane The angle between the horizontal axis of the tooth and the tangent axis, the torsion change of the tooth from point A to point B is the difference between the torsion angles of point A and point B; mark 18: the vertical displacement of the tooth moving from point A to point B, which is the second method The difference between the line distance of point A' at point A on the spool and the line distance of point B' at point B; mark 19: axis inclination angle, which is the angle between the long axis of the tooth and the subnormal axis from the tangent plane, and the distance between the tooth from point A to point B The inclination change is the difference between point A and point B; mark 20: inclination angle, is the angle between the long axis of the tooth on the normal plane and the subnormal axis, and the inclination change of the tooth from point A to point B is the difference between point A and Difference of inclination angle of point B

Detailed ways

The specific examples of the present invention will be described below with reference to the accompanying drawings in order to better illustrate the content of the present invention, but the illustrated implementation method is only an example and does not limit the protection scope of the present invention.

The method for establishing a coordinate system based on the target dental arch curve provided by the present invention specifically includes the following steps:

1. Obtain a digital model of the tooth:

By scanning the patient's upper and lower teeth in the mouth or outside the mouth, a digital three-dimensional tooth model is obtained, which has high-precision crown information;

2. Obtain the target dental arch curve based on the tooth arrangement before treatment or the big data dental arch curve:

(a) Select tooth feature points on the maxillary model and mandibular model respectively, as shown in Figure 1, including the midpoint (1) of the incisal margin of the central incisor and lateral incisor, the cusp of the canine, the first premolar and the second premolar The buccal cusp of the molars, the mesiobuccal cusp and the distal buccal point of the first and second molars (2), the characteristic points of the first and second molars can also be the mesiobuccal cusp and the distal buccal cusp the midpoint of the point to avoid the effect of tooth torsion;

(b) Using mathematical methods to fit the maxillary dental arch curve and the mandibular dental arch curve (3), the mathematical methods for fitting include polynomial equations, Beta functions, spline functions, etc.;

(c) The characteristic point of the tooth can also be the coronal axis point (4) as shown in Figure 2, or the geometric center point of the crown, or the functional cusp point, or the adjacent surface contact as shown in Figure 3 Point (5), if there is a gap between two adjacent teeth without contact, the contact point of the adjacent surface is the midpoint of the closest point of the two teeth;

(d) If due to missing individual teeth, impacted or obvious malposition, etc. The reason leads to the loss or dislocation of local tooth feature points, which leads to the asymmetry of the fitted dental arch curve. You can refer to the base bone shape on the dental model to supplement the missing tooth feature points or adjust the obviously dislocated feature points, and then proceed The fitting of the target dental arch curve, or mirroring the feature points of the bilateral teeth before fitting, and then fitting the target dental arch curve, for mild asymmetry, the dental arch curve can be directly constrained in the mathematical equation The symmetry of the dental arch curve can also be selected by the doctor according to the patient's treatment needs;

(e) As shown in Figure 1, the fitted dental arch curves have different shapes in three-dimensional directions. On the sagittal plane, the dental arch curve is in the shape of a Spee curve, and on the coronal plane, the dental arch curve is in the shape of a Wilson curve;

(f) It is also possible to obtain the maxillary dental arch curve and the mandibular dental arch curve according to the dental arch curve fitted by the big data dentition, select the appropriate dental arch curve shape in the big data, and then according to the patient's dental arch width, length and depth before treatment Determine the width, length and depth of the dental arch curve. The width of the dental arch is the distance between the first molars on both sides. The length of the dental arch is the vertical distance from the midpoint of the central incisor to the distal first molar on both sides. The vertical distance from the lowest point (usually the buccal cusp of the first premolar or the second premolar or between the two) to the line connecting the incisal edge of the central incisor and the buccal cusp of the second molar distal, in some embodiments, The second molar can also be used as a reference to determine the width and length of the arch curve, and the large data arch curve can be derived from the normal orthodontic treatment. The population, which can also be derived from the population after orthodontic treatment to obtain a normal occlusion;

(g) Automatically match the upper and lower dental arch curves, so that the upper and lower dental arch curves have uniform and normal coverage on the horizontal plane, that is, there is a certain distance between the upper and lower dental arch curves, which can be set by software set, the range does not exceed 3mm;

(h) Physicians or technicians can individually adjust the width, length, depth, shape of the dental arch curve and the matching degree of the upper and lower dental arch curves according to the treatment needs, and finally generate the target dental arch curve.

3. Establish the natural coordinate system of the curve based on the target dental arch curve, including the following steps:

(a) Select the midpoint on the target dental arch curve as the origin of the coordinate system. For any point on the dental arch curve, use the tangent line of the curve at that point as the tangent axis (6) of the local coordinate system, and the tangent axis The vertical plane is the normal plane;

(b) Starting from the origin of the coordinate system, determine the corresponding reference points for each tooth position on the dental arch curve in sequence according to the width of the patient's teeth;

(c) Determine the subnormal axis (8) of the local coordinate system on the normal plane where the reference point corresponding to each tooth position is located, the method is: compare each tooth position The standard reference values of crown axis inclination and crown inclination of the plane are transformed into the angle data of the tooth long axis relative to the dental arch curve, or according to the normal after treatment Dental model or untreated normal The big data of the dental model obtains the angle data of the long axis of each tooth relative to the dental arch curve, and the projection line of the long axis of the tooth on the normal plane is determined as the subnormal axis;

(d) Physicians can adjust the subnormal axis of each tooth position reference point in the software according to the needs of the patient's treatment plan;

(e) For the points between two reference points on the dental arch curve, use interpolation method or other mathematical methods to obtain the subnormal axis corresponding to each point;

(f) The tangent axis and subnormal axis of each point constitute the subtangent plane of the local coordinate system of the dental arch curve, and the perpendicular line from the tangent plane is the main normal axis (7), the tangent axis and the main normal axis form the close plane, The principal normal axis and the secondary normal axis constitute the normal plane;

(g) Finally, the natural coordinate system of the dental arch curve as shown in Figure 4 is established. The coordinate system has different coordinates at different points of the three-dimensional dental arch curve. The local coordinate system formed by the tangent plane and the normal plane.

The method for automatically aligning teeth based on the coordinate system of the target dental arch curve provided by the present invention specifically includes the following steps:

1. Obtain the target dental arch curve and establish the natural coordinate system of the curve according to the method provided by the present invention;

2. Automatically align the three-dimensional position of the teeth:

(a) select tooth feature points consistent with the tooth feature points of the fitted dental arch curve;

(b) The midpoint of the feature points of the central incisors on both sides coincides with the midpoint of the dental arch curve, and the teeth are moved in sequence so that the feature points of the teeth coincide on the dental arch curve;

(c) Check the adjacent collision, move the tooth along the dental arch curve, so that the adjacent surface of the tooth just touches, or keep a small amount of adjacent surface collision or a small amount of distance between the adjacent surfaces according to the requirements of the medical plan for deglazing the adjacent surface or reserve a gap;

3. Automatic alignment of teeth in three-dimensional angle:

(a) Determine the tooth transverse axis (9) and tooth long axis (10). The tooth long axis can be the principal component axis of mathematical calculation, or the connection between the crown center point (11) and the root center point (13). line, the connection line from the crown center point to the apex point (14) or the connection line from the apex point to the apex point, etc., when there is only the crown model, the apex point or root center point axis along the posterior teeth The line connecting the mesial ridge point and the distal ridge point in the direction of the central sulcus of the face is the connection line between the mesial ridge point and the distal ridge point in the direction of the cusp or incisal edge in the anterior teeth. The mesial-distal direction defines the tooth’s transverse axis, such as the line connecting the mesial and distal adjacent points, or The vertical line of the line connecting the tip of the cheek and the tip of the tongue, etc.;

(b) Rotate the tooth around the subnormal axis of the local curvilinear coordinate system of the tooth, so that the angle between the transverse axis of the tooth and the tangent axis of the curvilinear coordinate system on the close plane of the curvilinear coordinate system is 0, thereby positioning the crown torsion of the tooth, as shown in Figure 5 The central incisor crowns shown are twisted and aligned;

(c) Rotate the tooth around the principal normal axis of the tooth’s local curvilinear coordinate system, so that the tooth’s long axis and the subnormal axis of the curvilinear coordinate system reach a certain standard value on the secondary tangent plane of the curvilinear coordinate system, so as to locate the crown axis inclination of the tooth , the standard value is determined by the existing relative The standard value of coronal inclination of the plane is converted or obtained from the coronal inclination value of the relative curvilinear coordinate system measured by big data;

(d) Rotate the tooth around the tangent axis of the local curvilinear coordinate system of the tooth, so that the angle between the long axis of the tooth and the subnormal axis of the curvilinear coordinate system on the normal plane of the curvilinear coordinate system is 0, so as to locate the crown tilt of the tooth (crown torque ), the central incisor crowns are aligned obliquely as shown in Figure 6;

4. Self-inspection and personalized adjustment of occlusal relationship:

(a) Check the coverage between the upper and lower dentition, and move each tooth along the buccal and lingual direction along the main normal axis of the local coordinate system to achieve standard coverage between the upper and lower dentition, or set personalized coverage according to the requirements of the medical plan;

(b) To check the collision of the opposing jaws, each tooth moves up and down along the subnormal axis of the local coordinate system, so that there is light or no contact between the upper and lower jaws, or according to the requirements of the medical plan, the partial retention of heavy contact is set;

(c) Other angles of the teeth can also be adjusted appropriately to obtain a better bite;

(d) recheck the abutment collision, if the tooth needs to be moved along the desired arch curve, reposition the tooth's crown torsion, coronal inclination and coronal inclination after the movement,

(e) Check the coverage, check the collision of the opposing jaw, check the adjacent collision, and iteratively move and rotate the teeth in sequence, until the reasonable or personalized tooth arrangement is achieved to complete the automatic tooth arrangement;

(f) The ideal occlusal relationship parameters can generate a new coordinate system template.

The tooth movement evaluation method based on the coordinate system of the target dental arch curve provided by the present invention specifically includes the following steps:

1. Obtain the target dental arch curve and establish the natural coordinate system of the curve according to the method provided by the present invention;

2. According to the above-mentioned method provided by the present invention, the teeth are automatically aligned based on the dental arch curve coordinate system, and the technician or physician can manually adjust the results based on the results of the automatic tooth alignment according to the treatment needs to obtain the final target tooth alignment;

3. Calculate tooth coordinates:

(a) Define the direction of the coordinate system: in the natural coordinate system of the dental arch curve, the tangent axis of the curve is the near-distal direction of the tooth, the main normal axis is the lip (buccal) lingual (palatal) direction of the tooth, and the secondary method The line axis is the vertical direction of the tooth;

In the natural coordinate system of the dental arch curve, the normal plane of the curve is the lip (buccal) lingual (palatal) plane of the tooth, the tangent plane of the curve is the near-distal plane of the tooth, and the close plane of the curve is the horizontal plane of the tooth ;

(b) Select the tooth measurement point: as shown in Figure 7, the tooth measurement point can be the midpoint of the incisal margin or the cusp point (1), or the center point of the crown (11), or the center point of the tooth impedance (12). , root center point (13) or root apex point (14);

(c) Locate the local coordinate system of the tooth: locate the corresponding point of the tooth measurement point on the dental arch curve, which is the vertical point of the tooth measurement point on the dental arch curve, as shown in Figures 8-10, points A' and B' respectively It is the corresponding point of measuring points A and B on the dental arch curve when the tooth is in position A and B. If position B is the result of tooth automatic arrangement based on the coordinate system of the dental arch curve, point B and point B' may coincide. The local coordinate system established on the corresponding point of the dental arch curve is the local coordinate system of the tooth;

(d) Calculate the three-dimensional position of the tooth:

The mesio-distal coordinates refer to the tooth position on the tangent axis, that is, the curve distance between the corresponding point of the tooth measurement point on the alveolar arch curve and the origin of the curve coordinate system, as shown in Figure 8 and curve A'O in Figure 9;

The labial (cheek) lingual (palatal) coordinates refer to the tooth position on the main normal axis, that is, the straight-line distance between the vertical point of the tooth measurement point on the main normal axis and the corresponding point on the alveolar arch curve, as shown in Figure 8 Center line AA'(16);

The vertical coordinate refers to the position of the tooth on the subnormal axis, that is, the straight-line distance between the vertical point of the tooth measurement point on the subnormal axis and the corresponding point on the alveolar arch curve, as shown in Figure 9, the straight line AA'(18) ;

(e) Calculate the three-dimensional angle of the tooth:

The torsion angle refers to the angle between the tooth transverse axis and the curve tangent axis in the close plane (17);

Axis inclination refers to the angle between the long axis of the tooth and the subnormal axis of the curve on the tangent plane (19);

The inclination angle refers to the included angle (20) between the long axis of the tooth and the subnormal axis of the curve in the normal plane;

(f) Calculate the tooth coordinates of the initial position and the target position, and also calculate the tooth coordinates of any intermediate stage.

4. Calculation of tooth movement change: tooth movement change is equal to the difference between the initial tooth coordinates and the target tooth coordinates, including three-dimensional displacement and three-dimensional angle change, and the difference between the initial tooth coordinates and any stage tooth coordinates can also be calculated, and the evaluation Stage tooth movement changes;

Mesiodistal movement refers to the movement of the tooth along the tangential axis, that is, the change of the mesiodistal coordinates of the tooth, as shown in the arc length A'B'(15) of the curve in Figure 8 and Figure 9, where the movement close to the midpoint of the curve is the mesial movement , the movement away from the midpoint of the curve is distal movement;

The labial (buccal) lingual (palatal) movement refers to the movement of the teeth along the main normal axis, that is, the change in the labial (buccal) lingual (palatal) coordinates of the teeth, as shown in Figure 8. The difference between the line distances AA' and BB' (16 ), wherein, moving the lips (cheeks) means moving outwards, and moving the tongue (palate) means moving inwards;

Elongation and depression refer to the movement of the teeth along the subnormal axis, that is, the change of the vertical coordinates of the teeth, as shown in the difference between the AA' and BB' line distances in Fig. Moving upward is depressing, and vice versa for the lower jaw;

Torsion refers to the change of the twist angle on the close plane, such as the difference between the twist angle at position A and the position B in Figure 8;

The axis inclination refers to the change of the axis inclination on the tangent plane, as shown in Figure 9, the difference between the axis inclination at position A and the axis inclination at position B;

Tilt refers to the change of the tilt angle on the normal plane, such as the difference between the tilt angle at position A and the position B in Figure 10.

5. Output tooth coordinates and tooth movement changes: if the tooth coordinates and tooth movement changes are calculated for multiple measurement points of the teeth, multiple sets of tooth coordinates and tooth movement change scales are output.

For adolescent patients, during orthodontic treatment, the dental arch has growth changes in three dimensions: length, width, and depth. According to the prediction of the growth and development of the patient's jaw, the doctor can make personalized adjustments to the dental arch curve in three dimensions: length, width, and depth. For the coordinate system of the dental arch curve, the doctor can make appropriate adjustments according to the patient's characteristics and treatment needs, and set the coordinate angle of the personalized treatment concept, such as adjusting the subnormal axis and tangent axis, so as to obtain better automatic tooth arrangement results and better results. tooth movement evaluation results.

The drawings are only examples, and the invention is not limited to the embodiments shown in the drawings. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, equivalent changes and modifications made without departing from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims (8)

1. A method for establishing a coordinate system based on the target dental arch curve, which comprises the following steps in turn: obtaining the target dental arch curve based on the tooth arrangement before treatment or the large data dental arch curve; establishing the natural coordinate system of the curve based on the target dental arch curve, Among them, the specific method of obtaining the target dental arch curve based on the pre-treatment tooth arrangement or the big data dental arch curve is: (1) Obtain the digital dental model before treatment, select the tooth feature points on the upper jaw model and the lower jaw model respectively, and use mathematical methods The maxillary dental arch curve and the mandibular dental arch curve are respectively fitted, wherein the characteristic points of the teeth are the midpoint of the incisal edge of the incisor and the buccal cusp of the canine, premolar, and molar, and can also be the coronal axis point, tooth The geometric center point of the crown, the contact point of the proximal surface or the functional dimple point, the fitted dental arch curve has different shapes in the three-dimensional direction. On the horizontal plane, the dental arch curve can be roughly divided into pointed circle, oval circle, square circle and Personalized arch shape, on the sagittal plane, the dental arch curve is Spee curved shape, on the coronal plane, the dental arch curve is Wilson curved shape; or, the maxillary dental arch curve and Mandibular arch curve, select the appropriate arch shape in the big data, and determine the width, length and depth of the dental arch curve according to the width, length and depth of the dental arch before treatment; (2) pair the maxillary dental arch curve and the mandibular dental arch curve Perform automatic matching, so that the upper and lower dental arch curves have uniform and normal coverage on the horizontal plane; (3) Physicians or technicians can individually adjust the width, length, depth, shape and matching of the upper and lower dental arch curves according to treatment needs degree, and finally generate the target dental arch curve; Among them, the natural coordinate system of the curve is established according to the following steps: (1) The midpoint on the target dental arch curve is selected as the origin of the coordinate system, starting from the origin of the coordinate system, according to the width of the patient’s teeth, the teeth on the dental arch curve are sequentially determined. (2) For any point on the dental arch curve, take the tangent line of the curve at that point as the tangent axis of the local coordinate system, and the plane perpendicular to the tangent axis is the normal plane; (3) in each Determine the subnormal axis of the local coordinate system on the normal plane where the tooth position corresponds to the reference point. The method is: the standard reference value of the crown axis inclination and crown inclination of each tooth position relative to the plane is converted into the value of the long axis of the tooth relative to the dental arch curve. Angle data, or the angle data of the long axis of each tooth relative to the arch curve obtained from the big data of the normal dental model after treatment or the normal dental model without treatment, and the projection line of the tooth long axis on the normal plane is determined as the subnormal axis ;Physicians adjust the subnormal axis of each tooth position reference point according to the needs of the patient's treatment plan; for the points between two tooth position reference points on the dental arch curve, use interpolation method or other mathematical methods to obtain the subnormal axis corresponding to each point Normal axis; (4) The tangent axis and subnormal axis of each point constitute the secondary tangent plane of the local coordinate system of the dental arch curve, the vertical line from the tangent plane is the main normal axis, and the tangent axis and the main normal axis form an intimate plane, The main normal axis and the secondary normal axis constitute the normal plane; finally, different local positions composed of tangent axis, secondary normal axis, main normal axis, close plane, secondary tangent plane and normal plane are established at different points of the three-dimensional dental arch curve. The natural coordinate system of the dental arch curve of the coordinate system. 2. An automatic tooth alignment method, which uses the establishment method of the coordinate system based on the target dental arch curve according to claim 1 to carry out automatic tooth alignment. 3. The method for automatically arranging teeth according to claim 2, wherein the specific method for automatically arranging teeth based on the target dental arch curve coordinate system is: obtaining the target dental arch curve and establishing The natural coordinate system of the curve; select the tooth feature points that are consistent with the tooth feature points of the fitted dental arch curve; determine the tooth long axis and tooth transverse axis of the tooth; the midpoint of the central incisor feature points on both sides and the midpoint Point coincidence, make the characteristic points of all teeth coincide on the dental arch curve in sequence; the software checks the adjacent collision, moves the teeth along the dental arch curve, so that the adjacent points of the teeth touch without gaps or collisions, or retain a small amount of adjacent surfaces according to the requirements of the medical plan Collision or a small amount of distance between adjacent surfaces; rotate the tooth around the subnormal axis of the tooth’s local curvilinear coordinate system, so that the angle between the tooth’s transverse axis and the tangent axis of the curvilinear coordinate system on the close plane of the curvilinear coordinate system is 0, thereby positioning the crown of the tooth Torsion; rotate the tooth around the tangent axis of the local curve coordinate system of the tooth, so that the angle between the long axis of the tooth and the subnormal axis of the curve coordinate system on the normal plane of the curve coordinate system is 0, so as to locate the crown tilt of the tooth, that is, the crown torque ; Rotate the tooth around the principal normal axis of the local curvilinear coordinate system of the tooth, so that the tooth long axis and the secondary normal axis of the curvilinear coordinate system on the secondary tangent plane of the curvilinear coordinate system reach a certain standard value, thereby positioning the crown axis of the tooth. The standard value is converted from the existing standard value of crown axis inclination relative to the plane or obtained from the crown axis inclination value of the relative curved coordinate system measured by big data; check the coverage between the upper and lower dentition, each tooth along the local coordinates The main normal axis of the local coordinate system moves buccal and lingual to achieve standard coverage between the upper and lower dentition, or personalized coverage according to the medical plan; to check the collision of the opposite jaw, each tooth moves up and down along the secondary normal axis of the local coordinate system to make the upper and lower dentition Light contact or no contact between the jaws, or partial partial heavy contact is required according to the medical plan; in order to obtain a better occlusion and adjacent relationship, the angles of the teeth can also be adjusted appropriately; check the adjacent collision again, if the teeth need to follow the arch curve Move, reposition the crown torsion, crown axis tilt and crown tilt of the tooth after the move, check the overlay, check the collision of the opposite jaw, and iteratively move and rotate the teeth until a reasonable tooth arrangement is achieved and the automatic tooth arrangement is completed; ideal occlusion Relationship parameters can generate new coordinate system templates. 4. A method for evaluating tooth movement, which uses the method for establishing a coordinate system based on the target dental arch curve according to claim 1 to evaluate tooth movement. 5. The tooth movement evaluation method according to claim 4, characterized in that the tooth movement evaluation is performed according to the following steps: according to the method described in claim 2 or 3, the teeth are automatically aligned, and the technician or physician can according to the treatment needs Manually adjust on the basis of the automatic tooth alignment results to obtain the final target tooth arrangement; calculate tooth coordinates; calculate tooth movement changes; output tooth coordinates and tooth movement changes. 6. The tooth movement evaluation method according to claim 5, wherein the step of calculating tooth coordinates is: (1) defining the direction of the coordinate system: in the natural coordinate system of the dental arch curve, the tangent axis of the curve is In the near-distal direction of the tooth, the main normal axis is the labial-lingual direction of the tooth, and the secondary normal axis is the vertical direction of the tooth; in the natural coordinate system of the dental arch curve, the normal plane of the curve is the labial-lingual plane of the tooth, and the tangent The plane is the near-distal plane of the tooth, and the close plane of the curve is the horizontal plane of the tooth; (2) Calculate the coordinates of the tooth, including three-dimensional position and three-dimensional angle: locate the corresponding point of the tooth measurement point on the dental arch curve, and measure the tooth The vertical point on the dental arch curve, the local coordinate system established on the corresponding point of the dental arch curve is the local coordinate system of the tooth; the mesio-distal coordinate refers to the position of the tooth on the tangent axis, that is, the tooth measurement point is in the alveolar The curve distance between the corresponding point on the bow curve and the origin of the curve coordinate system; the labial-lingual coordinate refers to the tooth position on the main normal axis, that is, the correspondence between the vertical point of the tooth measurement point on the main normal axis and the alveolar arch curve The straight-line distance between points; the vertical coordinate refers to the position of the tooth on the subnormal axis, that is, the straight-line distance between the vertical point of the tooth measurement point on the subnormal axis and the corresponding point on the alveolar arch curve; the torsion angle is Refers to the angle between the transverse axis of the tooth and the tangent axis of the curve in the close plane; the axis inclination refers to the angle between the long axis of the tooth and the subnormal axis of the curve in the tangent plane; the inclination angle refers to the long axis of the tooth and the curve in the normal plane The included angle of the subnormal axis; calculate the tooth coordinates of the initial position and the target position, and also calculate the tooth coordinates of the intermediate stage. 7. The tooth movement evaluation method according to claim 5, characterized in that the step of calculating the tooth movement change is: the tooth movement change is equal to the difference between the initial tooth coordinates and the target tooth coordinates, including three-dimensional displacement and three-dimensional angle change ; It is also possible to calculate the difference between the initial tooth coordinates and the tooth coordinates at any stage, and to evaluate the change of tooth movement in the stage; the mesio-distal movement refers to the movement of the teeth along the tangent axis, that is, the change of the mesio-distal coordinates of the teeth. The movement of the point is the mesial movement, and the movement away from the midpoint of the curve is the distal movement; the labial and lingual movement refers to the movement of the teeth along the main normal axis, that is, the change of the labial and lingual coordinates of the teeth. Among them, the labial movement refers to the outward movement, and the lingual movement Movement refers to the inward movement; elongation and depression refer to the movement of the teeth along the subnormal axis, that is, the change of the vertical coordinates of the teeth. Among them, the downward movement of the upper jaw is elongation, and the upward movement is depression, and the lower jaw is vice versa; The change of the torsion angle on the close plane; the axial tilt refers to the change of the axial inclination angle on the tangent plane; the tilt refers to the change of the inclination angle on the normal plane. 8. The tooth movement evaluation method according to claim 6, wherein the tooth measurement points for evaluating the amount of tooth movement include cusp points or midpoints of incisal margins, crown center points, root center points, tooth impedance center points, and Apex point.

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