CN112137739B - Digital dental crown design method and device - Google Patents
Digital dental crown design method and device Download PDFInfo
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- CN112137739B CN112137739B CN202010973883.XA CN202010973883A CN112137739B CN 112137739 B CN112137739 B CN 112137739B CN 202010973883 A CN202010973883 A CN 202010973883A CN 112137739 B CN112137739 B CN 112137739B
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- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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- A61C5/00—Filling or capping teeth
- A61C5/70—Tooth crowns; Making thereof
- A61C5/77—Methods or devices for making crowns
Abstract
The embodiment of the invention provides a digital dental crown design method and equipment, wherein the method comprises the steps of obtaining an occlusion model of an upper jaw and a lower jaw and a standard dental crown model at a tooth missing position; placing the standard dental crown model into a corresponding edentulous part in the upper and lower jaw occlusion model to obtain a designed dental crown model; performing expansion treatment on all designed crown models, and trimming each designed crown model in sequence to remove expansion overlapped parts of the designed crown models and other designed crown models which are not subjected to trimming operation; and expanding the occlusion model of the upper jaw and the lower jaw, and trimming the designed dental crown model to remove the expansion superposition part of the designed dental crown model and the adjacent teeth. According to the digital dental crown design method, the designed dental crown model is properly trimmed, so that a certain gap is reserved between the designed dental crown model and other designed dental crown models around the designed dental crown model or normal adjacent teeth, the problems of difficult installation, blocking and the like are avoided, the subsequent installation is convenient, and the workload of manually grinding and adjusting the dental crown by a doctor is reduced.
Description
Technical Field
The invention relates to the technical field of oral restoration, in particular to a digital dental crown design method and digital dental crown design equipment.
Background
Many factors in daily life cause tooth loss, and the dental implant is gradually a common method for repairing lost teeth compared with a fixed denture and a movable denture. The final step in the dental implant restoration is to install the prepared crown on the implant abutment. The design and manufacture of the dental crown will affect the aesthetic degree of the oral cavity and whether the occlusion relationship between the upper and lower teeth is normal.
Since the application of CAD/CAM technology in the field of dental restoration, the traditional denture design and manufacturing method is fundamentally changed. But existing methods also exist when designing crowns such as: the surface of the dental crown is difficult to partially trim, the form design of the dental crown lacks the flexibility of interaction, the difficulty of designing a plurality of dental crowns is high, the design steps of the dental crown are more, the design time is long, and the like.
Disclosure of Invention
The embodiment of the invention provides a digital dental crown design method and equipment, which are used for solving the problems of difficult trimming, lack of interaction and long time consumption of the dental crown design method in the prior art and designing an ideal dental crown in a digital mode.
The embodiment of the invention provides a digital dental crown design method, which comprises the following steps:
obtaining an occlusion model of upper and lower jaws and a standard dental crown model at the edentulous part;
Placing the standard dental crown model into a corresponding tooth missing position in the upper and lower jaw occlusion model to obtain a designed dental crown model;
performing expansion treatment on all the designed dental crown models, and trimming each designed dental crown model in sequence to remove expansion overlapped parts of the designed dental crown models and other designed dental crown models which are not subjected to trimming operation;
and expanding the upper and lower jaw occlusion models, and trimming the designed dental crown model to remove the expansion superposition part of the designed dental crown model and the adjacent teeth.
According to the digital dental crown design method of one embodiment of the present invention, the expanding process is performed on all the design dental crown models, further comprising:
generating distance field data for all of the designed crown models;
and extracting an expansion isosurface from the distance field data based on an isosurface generation algorithm, wherein the distance value of the expansion isosurface from the designed dental crown model is a preset expansion gap value.
According to a digital crown design method of an embodiment of the invention, the generating distance field data for all of the design crown models further comprises:
respectively generating an outer bounding box for each designed crown model, and respectively moving six faces of the outer bounding box outwards for a first preset distance to obtain a first cubic area corresponding to each designed crown model;
Generating a three-dimensional cubic grid based on the first cubic region;
traversing each grid point a in the three-dimensional cubic grid, calculating the shortest distance value d between the grid point a and the designed dental crown model, and judging whether the grid point a is inside or outside the designed dental crown model;
defining the distance value d as a positive value when the grid point a is outside the designed crown model; defining the distance value d as a negative value when the grid point a is inside the designed dental crown model; defining a distance value d of 0 when the grid point a is located on the surface of the designed crown model; and taking the distance value d as a scalar of the grid point a to obtain three-dimensional cubic grid data with the scalar, namely the distance field data of the designed dental crown model.
According to a digital dental crown design method of an embodiment of the present invention, the expanding the upper and lower jaw occlusion models and trimming the design dental crown model to remove an expanded overlapping portion of the adjacent tooth in the design dental crown model, further comprising:
respectively generating outer bounding boxes for the designed crown model, and respectively moving six faces of the outer bounding boxes outwards for a second preset distance to obtain a second cubic area of the designed crown model;
Trimming the occlusion model of the upper jaw and the lower jaw, and reserving a superposed part of the occlusion model of the upper jaw and the lower jaw and the second cubic area to obtain an area adjacent tooth model;
and performing expansion treatment on the region adjacent tooth model, and trimming the design dental crown model to remove the expansion superposition part of the adjacent tooth in the design dental crown model.
According to an embodiment of the present invention, the digital dental crown design method further comprises, after the expanding the upper and lower jaw occlusion models and trimming the design dental crown model to remove an expanded overlapping portion of the adjacent teeth in the design dental crown model:
identifying a triangular surface patch and a pointed triangular surface patch of a high refraction edge in the designed dental crown model, and marking;
deleting the triangular patch and the pointed triangular patch where the marked high refraction edge is located;
and repairing the hole in the designed dental crown model.
According to the digital dental crown design method of the embodiment of the invention, the method for identifying and marking the triangular surface patch of the designed dental crown model where the high refraction edge is located further comprises the following steps:
traversing each first edge on each triangular patch c of the designed dental crown model, and obtaining another triangular patch n adjacent to the first edge;
Calculating an included angle alpha of a normal between the triangular surface patch c and the triangular surface patch n;
when the numerical value of the included angle alpha is larger than a preset first included angle threshold value, marking the triangular patch c and the triangular patch n as triangular patches where the height refraction edges are located;
the identifying and marking of the pointed triangular surface patch in the designed dental crown model further comprises:
traversing each vertex p on the designed dental crown model and each second edge connected with the vertex p;
calculating an included angle beta between the second edge and the normal of the vertex p, wherein if the included angle beta is an obtuse angle, a complementary angle of the included angle beta is taken as a new included angle beta;
and when the numerical values of at most two included angles in all the included angles beta related to the vertex p are larger than a preset second included angle threshold value, all the triangular patches containing the vertex p are marked as pointed triangular patches.
According to the digital dental crown design method of one embodiment of the invention, after identifying and marking the triangular patch and the sharp triangular patch where the high refraction edge is located in the designed dental crown model, the method further comprises the following steps:
expanding the ranges of the triangular patch where the high refraction edge is located and the pointed triangular patch and marking;
Wherein, expand the range of the triangle facet at which the high refraction limit is located and mark, further include:
traversing the remaining first edges of the triangular patch identified as the high refraction edge and obtaining another triangular patch n' adjacent to the first edge;
calculating the included angle of the normal between the triangular surface patch where the height refraction edge is located and the triangular surface patch n';
when the included angle is larger than a preset first included angle threshold value, identifying the triangular patch n' as a triangular patch where a height refraction edge is located;
wherein, expand the scope of the said sharp triangular patch and mark, further include:
traversing the other vertexes p 'marked as the pointed triangular patch and each second edge connected with the vertexes p';
calculating an included angle beta ' between the second edge and the normal of the vertex p ', wherein if the included angle beta ' is an obtuse angle, a complementary angle of the included angle beta ' is taken as a new included angle beta ';
and when the numerical values of at most two included angles in all the included angles beta ' related to the vertex p ' are greater than a preset second included angle threshold value, marking the rest triangular patches including the vertex p ' as pointed triangular patches.
The digital dental crown design method according to one embodiment of the present invention further comprises, after the repairing the hole in the designed dental crown model:
manually smoothing selected regions in the designed crown model based on a triangular face smoothing algorithm.
According to the digital dental crown design method of one embodiment of the invention, the obtaining of the maxillo-mandibular occlusion model and the standard dental crown model at the edentulous site further comprises:
acquiring an upper jaw three-dimensional model and a lower jaw three-dimensional model which are scanned independently and CBCT data shot in a bite state;
and registering the upper jaw three-dimensional model and the lower jaw three-dimensional model based on the CBCT data to obtain the upper and lower jaw occlusion model.
Embodiments of the present invention further provide an electronic device, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to implement the steps of the digital crown design method as described in any of the above.
The digital dental crown design method and the device thereof provided by the embodiment of the invention are characterized in that the digital dental crown design method generates one or more designed dental crown models based on the occlusion models of the upper jaw and the lower jaw and the existing three-dimensional model of the standard dental crown, and the designed dental crown models are properly trimmed, so that a certain gap is reserved between the designed dental crown models and other designed dental crown models around the designed dental crown models or normal adjacent teeth, the problems of difficult installation, blocking and the like caused by factors such as manufacturing errors or implant implantation errors and the like in the actual installation process of the dental crown are avoided, the subsequent installation is convenient, and the workload of manually grinding and adjusting the dental crown by a doctor is reduced. The dental crown three-dimensional model designed by the digital dental crown design method can be installed and worn by a patient after being processed and manufactured by modes such as CAM (computer aided manufacturing) or 3D (three-dimensional) printing, and the like, can generally directly meet actual requirements or only needs a small amount of fine adjustment, greatly improves the working efficiency of dentists, and reduces the waiting time of the patient.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic flow chart of a digital dental crown design method according to an embodiment of the present invention;
FIG. 2 is a schematic representation of an expansion process for a plurality of designed dental crowns in an embodiment of the present invention;
FIG. 3 is a schematic view of a process for creating a gap between adjacent designed dental crown models in an embodiment of the present invention;
FIG. 4 is a schematic view of another embodiment of the present invention illustrating the process of creating a gap between adjacent designed dental crown models;
FIG. 5 is a simplified schematic diagram of an embodiment of the present invention for creating an expanded iso-surface for a designed crown model based on distance field data;
FIG. 6 is a schematic representation of a designed dental crown model with a generated gap between an adjacent tooth according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a triangular patch and a sharp triangular patch in which a high refractive edge is located in a designed dental crown model according to an embodiment of the present invention;
Fig. 8 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Reference numerals are as follows:
1. designing a dental crown model; 11. A first designed crown model;
12. a second design crown model; 13. A third designed crown model;
2. an upper and lower jaw occlusion model; 21. A three-dimensional model of the upper jaw; 22. A lower jaw three-dimensional model;
3. an adjacent tooth; 4. A first cubic region; 5. Expanding the isosurface;
6. a second cubic region; 7. A region adjacent tooth model;
8. an electronic device; 81. A processor; 82. A communication interface;
83. a memory; 84. A communication bus.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the embodiments of the present invention, it should be noted that the terms "first", "second" and "third" are used for the sake of clarity in describing the numbering of the components of the product and do not represent any substantial difference, unless explicitly stated or limited otherwise. "upper", "lower", "left", "right", and the like are used only to indicate relative positional relationships, and when the absolute position of the object to be described is changed, the relative positional relationships may also be changed accordingly. Specific meanings of the above terms in the embodiments of the present invention can be understood by those of ordinary skill in the art according to specific situations.
It is to be understood that, unless otherwise expressly specified or limited, the term "coupled" is used broadly, and may, for example, refer to directly coupled devices or indirectly coupled devices through intervening media. Specific meanings of the above terms in the embodiments of the invention will be understood to those of ordinary skill in the art in specific cases.
As shown in fig. 1 to 6, a digital dental crown design method according to an embodiment of the present invention includes:
step S100: and acquiring the upper and lower jaw occlusion model 2 and a standard dental crown model at the tooth missing position.
Specifically, the maxillomandibular occlusion model 2 can be acquired by a wireless three-dimensional digital scanning instrument. Generally, in a tooth occlusion state, a conventional intraoral scanning instrument cannot enter an oral cavity for scanning, so that complete data cannot be directly obtained, in order to obtain a complete three-dimensional model of the upper and lower jaws of a patient in the occlusion state, based on CBCT (Cone beam Computer Tomograph, oral cavity and maxillofacial Cone beam CT) data shot in the occlusion state, the complete upper jaw three-dimensional model 21 and the lower jaw three-dimensional model 22 which are scanned independently can be respectively registered, that is, the original independent upper jaw three-dimensional model 21 and the lower jaw three-dimensional model 22 are matched together according to an occlusion relationship through the CBCT data, so that the upper and lower jaw occlusion model 2 is obtained.
The standard crown model at the edentulous site may select a three-dimensional model corresponding to the crown at the respective edentulous site directly from a pre-stored database of standard crowns. Different teeth have different functions and different forms, and corresponding standard dental crown models can be obtained by inducing and integrating the forms of the teeth at different positions, and then a database is established. The standard dental crown database stores three-dimensional models of different teeth, and provides a foundation for dental prosthesis.
Step S200: as shown in fig. 2, a standard crown model is placed in the corresponding edentulous portion of the maxillo-mandibular occlusion model 2 to obtain a designed crown model 1.
Specifically, based on the upper and lower jaw occlusion model 2, the standard dental crown model is dragged and dropped to a proper position in a three-dimensional space, and the basic size and shape of the standard dental crown model are adjusted through a control, for example, the standard dental crown model can be respectively scaled in three directions of length, width and height, the size of the standard dental crown model is adjusted to adapt to different patients, the standard dental crown model is optimally just contacted with the adjacent teeth 3 (normal teeth in the upper and lower jaw occlusion model 2), gaps or interference can also be properly existed, and further trimming processing is performed subsequently, wherein the coarse adjustment is mainly performed.
Step S300: as shown in fig. 2, 3 and 4, the expansion process is performed on all the design crown models 1, and each of the design crown models 1 is trimmed in turn to remove the expansion overlapping portion of the design crown model 1 with other design crown models which are not subjected to the trimming process.
Specifically, when a plurality of crown designs are performed simultaneously, as shown in fig. 2, the first designed crown model 11, the second designed crown model 12 and the third designed crown model 13 are all located at the tooth lacking position, and if the position and size of these designed crown models 1 are just kept in contact during the design, in the actual installation process of the crown, due to the influence of various factors such as manufacturing errors or implant implantation errors, problems such as difficult installation (e.g., jamming during installation) may occur, and further, a doctor is required to manually adjust the crown (e.g., grinding off the contact partial region), thereby increasing the waiting time of a patient and the workload of the doctor. Therefore, a certain gap is reserved between the dental crowns during design, and the subsequent actual dental crowns can be conveniently installed.
To achieve this, each design crown model 1 (shown by a solid line in fig. 2) is expanded, the expanded model is shown by a dotted line in fig. 2, and the distance between the expanded model and the design crown model 1 can be set by parameters, typically around 0.4mm, to secure a crown setting gap.
Then, Boolean subtraction operation is carried out on each designed dental crown model 1 and other models which are not subjected to trimming operation and are expanded to trim the current designed dental crown model 1. More specifically, when the trimming order is different for a plurality of designed crown models 1, different trimmed crown models are obtained.
As shown in fig. 3, the trimming sequence is: first designed crown model 11 → second designed crown model 12 → third designed crown model 13. Firstly, the first designed dental crown model 11 is respectively subjected to Boolean reduction operation with the expanded models of the second designed dental crown model 12 and the third designed dental crown model 13, the first designed dental crown model 11 is trimmed, and the part of the first designed dental crown model 11, which is overlapped by the expanded model of the second designed dental crown model 12 on the right side, is removed, and the part of the first designed dental crown model 11, which is overlapped by the expanded model of the third designed dental crown model 13 on the upper side, is also removed. After the first designed crown model 11 is trimmed by boolean operations, a set gap is ensured between the first designed crown model 11 and the second designed crown model 12 and the third designed crown model 13.
The same trimming operation is then performed on the second designed crown model 12, skipped because the boolean operation has already been performed between the expanded models of the first and second designed crown models 11, 12. The second designed crown model 12 is then trimmed to leave a gap between the expanded models of the second and third designed crown models 12, 13 by performing a boolean operation. As can be seen in FIG. 3, the second designed crown model 12 is not in contact with the expanded model of the third designed crown model 13 and therefore the second designed crown model 12 is unchanged after the Boolean operation.
The same trimming operation is finally performed on the third designed crown model 13, which is skipped since the third designed crown model 13 has already been boolean operated with the first and second designed crown models 11, 12. The resulting first designed crown model 11 is trimmed of the superior and right portions while the shapes of the second designed crown model 12 and the third designed crown model 13 remain unchanged.
In addition, other trimming sequences may be used, as shown in fig. 4, the trimming sequence is: second designed crown model 12 → first designed crown model 11 → third designed crown model 13. First, the second designed crown model 12 is subjected to a boolean subtraction operation with the expanded models of the first designed crown model 11 and the third designed crown model 13, respectively, and the second designed crown model 12 is trimmed to remove a portion of the second designed crown model 12 where the left portion overlaps the expanded model of the first designed crown model 11. Since the second design crown model 12 is not in contact with the expanded model of the third design crown model 13, no further trimming of the second design crown model 12 is required.
The same trimming operation is then performed on the first designed crown model 11, skipped because a boolean operation has already been performed between the expanded models of the first and second designed crown models 11, 12. Next, boolean operation is performed on the expanded models of the first designed crown model 11 and the third designed crown model 13 to trim the first designed crown model 11, and a portion of the first designed crown model 11 where the upper portion coincides with the expanded model of the third designed crown model 13 is removed, leaving a gap therebetween.
The same trimming operation is finally performed on the third designed crown model 13, which is skipped since the third designed crown model 13 has already been boolean operated with the first and second designed crown models 11, 12. The resulting first design crown model 11 is trimmed of the upper side portion, the second design crown model 12 is trimmed of the left side portion, and the shape of the third design crown model 13 remains unchanged.
When other pruning sequences are adopted, the processing method is similar to the above method, and the description is omitted here. In summary, a boolean subtraction operation is performed between each designed crown model 1 and the remaining crowns that have not undergone the boolean operation with respect to the designed crown model 1 to trim the designed crown model 1 so that a certain gap exists between the designed crown model and other designed crown models. The designer can select an appropriate trimming sequence according to actual requirements. In a specific embodiment, the designed crown model 1 may be selected to be trimmed first with the largest contact surface with other designed crown models.
Step S400: and (3) performing expansion treatment on the upper and lower jaw occlusion models 2, and trimming the designed dental crown model 1 to remove the expansion overlapped part of the designed dental crown model 1 and the adjacent tooth 3.
Specifically, the expansion processing method similar to step S300 may be adopted to perform the expansion processing on the upper and lower jaw occlusion models 2 to generate the expansion model of the adjacent tooth 3 corresponding to the designed dental crown model 1, and then perform the boolean reduction operation on the expansion models of the designed dental crown model 1 and the adjacent tooth 3 to remove the expansion overlapping portion with the adjacent tooth 3 in the designed dental crown model 1.
The digital dental crown design method provided by the embodiment is based on the upper and lower jaw occlusion models 2 and the existing standard dental crown three-dimensional model, a single or a plurality of designed dental crown models 1 are generated, the designed dental crown models 1 are properly trimmed, certain gaps are reserved between the designed dental crown models 1 and other designed dental crown models 1 around the designed dental crown models or normal adjacent teeth 3, the problems of difficult installation, blocking and the like caused by factors such as manufacturing errors or implant implantation errors in the actual installation process of the dental crowns are avoided, the subsequent installation is convenient, and the workload of manual grinding and adjustment of the dental crowns of doctors is reduced. The dental crown three-dimensional model designed by the digital dental crown design method can be installed and worn for a patient after being processed and manufactured by modes such as CAM or 3D printing, and the like, can generally directly meet actual requirements or only needs a small amount of fine adjustment, greatly improves the working efficiency of dentists, and reduces the waiting time of the patient.
Further, as shown in fig. 5, step S300 further includes:
step S310: distance field data was generated for all designed crown models 1. Let the pixel spacing of the distance field be space.
Wherein, step S310 further includes:
step S311: an outer bounding box (i.e. the smallest cube containing the designed crown model 1) is generated for each designed crown model 1, and six faces of the outer bounding box are moved outwards by a first preset distance to obtain a first cubic region 4 corresponding to each designed crown model 1. In particular, the first predetermined distance is greater than a predetermined expansion gap value, which in one particular embodiment may be gap + space 2, where gap is the predetermined expansion gap value, i.e., the predetermined gap between the design crown model 1 and the surrounding teeth, to ensure that the expanded model of the design crown model 1 remains within the distance field.
Step S312: based on the first cubic region 4, a three-dimensional cubic grid is generated. Specifically, the grid line intersection represents one pixel, and the pixel interval is space, representing the sampling interval. The smaller the value of the sampling interval, the denser the sampling points. In a specific embodiment, the pixel spacing is set to 0.3 mm.
Step S313: traversing each grid point a in the three-dimensional cubic grid, calculating the shortest distance value d between the grid point a and the designed dental crown model 1, and judging whether the grid point a is inside or outside the designed dental crown model 1. When the grid point a is outside the designed dental crown model, defining the distance value d as a positive value; when the grid point a is in the interior of the designed dental crown model, defining the distance value d as a negative value; when the grid point a is located on the surface of the designed crown model, the distance value d is defined to be 0.
Step S314: and taking the distance value d as a scalar of the grid point a to obtain three-dimensional cubic grid data with the scalar, namely the distance field data of the designed dental crown model 1.
Step S320: based on an isosurface generation algorithm, an expansion isosurface 5 is extracted from the distance field data, and the distance value d of the expansion isosurface 5 to the designed dental crown model 1 is a preset expansion gap value gap. Specifically, the iso-surface generation algorithm may adopt a Marching Cubes algorithm, and the distance value from each sampling point on the expanded iso-surface 5 to the designed dental crown model 1 is the same.
By inputting the target gap size gap in the iso-surface extraction algorithm, i.e. extracting the iso-surface which is gap away from the designed dental crown model 1, the expanded designed dental crown model 1 is generated, and the model cannot generate self-intersection. If the designed dental crown model 1 is expanded by a method of directly expanding along the normal direction, self-intersection is easily generated at the recessed portion due to the surface roughness of the designed dental crown model 1, which may seriously affect the subsequent calculation and the final manufacturing. And the self-intersection condition can be well avoided by using the isosurface extraction algorithm.
Further, as shown in fig. 6, step S400 further includes:
step S410: respectively generating outer bounding boxes for designing the dental crown model 1, and respectively moving six faces of the outer bounding boxes outwards for a second preset distance to obtain a second cubic area 6 containing the designed dental crown model 1. In particular, the second predetermined distance may be selected as a practical matter, and in one particular embodiment is 1mm to ensure that the designed crown model 1 is inside the second cubic area 6, rather than against the margin.
Step S420: and trimming the upper and lower jaw occlusion model 2, and keeping the overlapped part of the upper and lower jaw occlusion model 2 and the second cubic area 6 to obtain an area adjacent tooth model 7. The maxillomandibular occlusion model 2 can be obtained by performing a boolean operation on the separated maxillomandibular three-dimensional model 21 and the mandible three-dimensional model 22.
Because the data volume of the upper and lower jaw occlusion model 2 is large, the number of triangular meshes is large, in order to improve the operation performance, the upper and lower jaw occlusion model 2 is trimmed by using the second cubic area 6, and the part of the upper and lower jaw occlusion model 2 which is not adjacent to the designed dental crown model 1 can be removed by adopting Boolean subtraction operation, so that a new model, namely an area adjacent tooth model 7 is obtained. As shown in fig. 6, the region adjacent tooth model 7 includes partial adjacent tooth models adjacent to the upper side, the left side and the right side of the designed crown model 1.
Step S430: the region adjacent tooth model 7 is subjected to expansion processing, and the design crown model 1 is trimmed to remove the expansion overlapping part of the design crown model 1 with the adjacent tooth 3.
Specifically, the regional adjacent tooth model 7 is expanded according to a preset expansion gap value, and the expansion gap value can be obtained by using an isosurface generation algorithm, so that the expanded regional adjacent tooth model 7 (the part shown by the dotted line in the second cube region 6) is obtained. And carrying out Boolean subtraction on the designed dental crown model 1 and the expanded region adjacent tooth model 7, cutting off the expansion superposition part of the designed dental crown model 1 and the adjacent tooth 3, and keeping the designed dental crown model 1 and the adjacent tooth 3 in a set gap.
By adopting the method for processing, the calculation amount of Boolean operation can be reduced, the calculation process is accelerated, and the design fluency is improved. It should be noted that, during the process of performing boolean operations on the three-dimensional model for trimming, due to the local surface unevenness of the model, some loose fragments of the designed dental crown model 1 may be generated after trimming, and the largest model needs to be extracted as a new designed dental crown model 1. For the convenience of calculation, the number of triangular faces of the model can be compared for judgment.
Further, after step S400, the method further includes:
step S500: and removing the high refraction edge and the sharp object generated in the Boolean operation.
The three-dimensional model of the crown after trimming by boolean operation may generate a highly refractive edge (the normal direction of the triangular patches on both sides of the edge is very different) and a sharp object (a single-point peak on the curved surface mesh), which needs to be deleted to repair the model.
The step S500 further includes:
step S510: and identifying a triangular surface patch and a pointed triangular surface patch where the high-degree refraction edge is positioned in the designed dental crown model, and marking.
Step S520: and deleting the triangular patch and the pointed triangular patch where the marked high refraction edge is positioned.
Step S530: the holes in the designed dental crown model 1 are repaired.
Specifically, the hole in the designed crown model 1 may be repaired by a three-dimensional model hole repairing method, such as a mesh-based repairing method, a volume expression-based repairing method, a curvature feature mesh-based repairing method, or a radial basis function-based repairing method, which are all the prior art and will not be described herein again.
Since new high refraction edges and spikes may be generated during the hole repairing operation, the steps S510 to S530 may be iterated multiple times to delete the new high refraction edges and spikes as much as possible (for example, the iteration number may be set to 5).
Further, as shown in fig. 7, the identifying and marking the triangular patch where the high refractive edge is located in the designed dental crown model 1 in step S510 further includes:
step S511-1: each first edge on each triangular patch c of the design crown model 1 is traversed and another triangular patch n adjacent to the first edge is taken.
Step S512-1: and calculating an included angle alpha of the normal between the triangular patch c and the triangular patch n.
Step S513-1: and when the numerical value of the included angle alpha is larger than a preset first included angle threshold value, marking the triangular patch c and the triangular patch n as triangular patches where the high refraction edges are located. The first angle threshold may be 125 deg. to 145 deg., and in one specific embodiment, the first angle threshold may be set to 135 deg..
As shown in fig. 7, the identifying and marking the sharp triangular patch in the designed dental crown model 1 in step S510 further includes:
step S511-2: traversing each vertex p on the designed dental crown model 1 and each second edge connected with the vertex p;
step S512-2: and calculating an included angle beta between the second edge and the normal of the vertex p, wherein if the included angle beta is an obtuse angle, a complementary angle of the included angle beta is taken as a new included angle beta, and the included angle beta is made to be 180-beta, namely an acute angle is selected as the included angle beta.
Step S513-2: and when the numerical values of at most two included angles in all the included angles beta related to the vertex p are larger than a preset second included angle threshold value, all the triangular patches containing the vertex p are marked as pointed triangular patches. The larger the angle β, the gentler the mesh surface at the vertex p. The second angle threshold may be 70-85 deg., and in one specific embodiment, the second angle threshold is set to 80 deg..
Further, after step S510, the method further includes:
the range of the high-refraction triangular patch and the cusp triangular patch is expanded and marked.
Wherein, the range of the high refraction triangular patch is expanded and marked, further comprising:
step S514-1: traversing the rest of the first edges of the triangular patch identified as the high refraction edge and obtaining another triangular patch n' adjacent to the first edge;
step S515-1: calculating the included angle of the normal between the triangular patch where the height refraction edge is located and the triangular patch n';
step S516-1: and when the included angle is larger than a preset first included angle threshold value, identifying the triangular patch n' as the triangular patch where the high refraction edge is located.
Wherein, expand the scope of the triangle patch of point form and mark, further include:
Step S514-2: traversing the other vertexes p 'marked as the pointed triangular surface patch and each second edge connected with the vertexes p';
step S515-2: calculating an included angle beta ' between the second edge and the normal of the vertex p ', wherein if the included angle beta ' is an obtuse angle, a complementary angle of the included angle beta ' is taken as a new included angle beta ';
step S516-2: and when the numerical values of at most two included angles in all the included angles beta ' related to the vertex p ' are larger than a preset second included angle threshold value, identifying the other triangular patches containing the vertex p ' as pointed triangular patches.
FIG. 7 is a schematic view of a highly refractive edge and a spike. The above steps will be described below by taking a cusp triangular patch as an example. A circle of triangular patches collectively including p points forms a spike, which can be determined in step S510 to identify the triangular patch of the spike. Since the fluctuation of the grid surface is often existed in the vicinity of the spikes, the crown model 1 is designed for better restoration, and the remaining vertexes (p in the figure) on the triangle patch of the spikes with the identified positions are continuously traversed and marked1、p2、p3、p4) The other connected circle of triangular patches, namely the triangular patch with the corresponding spike, is locally expanded. Similarly, the region where the highly refractive edge is located may be similarly processed.
Further, after step S530, the method further includes:
step S600: and manually smoothing the selected area in the designed dental crown model 1 based on a triangular surface smoothing algorithm.
If the surface of the designed dental crown model 1 generated according to the above steps is not smooth enough, the user can select a region with a set size on the surface of the designed dental crown model 1 by using a mouse (the size of the region can be set by parameters), and the selected region is smoothed manually by adopting a triangular surface smoothing algorithm.
As shown in fig. 8, an embodiment of the present invention further provides an electronic device 8, including: a processor (processor)81, a communication Interface (Communications Interface)82, a memory (memory)83 and a communication bus 84, wherein the processor 81, the communication Interface 82 and the memory 83 complete communication with each other through the communication bus 84. The processor 81 may invoke logic instructions in the memory 83 to perform the steps of the digital crown design method as in any of the embodiments described above.
In addition, the logic instructions in the memory 83 may be implemented in the form of software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In another aspect, embodiments of the present invention also provide a computer program product comprising a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions, which when executed by a computer, enable the computer to perform the digital crown design method provided by the above-described method embodiments.
In yet another aspect, the embodiments of the present invention further provide a non-transitory computer readable storage medium, on which a computer program is stored, the computer program being implemented by a processor to perform the digital crown design method provided by the above embodiments.
It can be seen from the above embodiments that the digital dental crown design method and apparatus provided by the present invention, wherein the digital dental crown design method generates one or more designed dental crown models 1 based on the upper and lower jaw occlusion models 2 and the existing standard dental crown three-dimensional model, and the designed dental crown model 1 is properly trimmed to reserve a certain gap between the designed dental crown model 1 and other designed dental crown models 1 around the designed dental crown model or normal adjacent teeth 3, thereby avoiding the problems of difficult installation, jamming and the like caused by factors such as manufacturing errors or implant implantation errors during the actual installation of the dental crown, facilitating the subsequent installation, and reducing the workload of manual grinding adjustment of the dental crown by the doctor. The dental crown three-dimensional model designed by the digital dental crown design method can be installed and worn for a patient after being processed and manufactured by modes such as CAM or 3D printing, and the like, can generally directly meet actual requirements or only needs a small amount of fine adjustment, greatly improves the working efficiency of dentists, and reduces the waiting time of the patient.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A digital crown design method, comprising:
obtaining an occlusion model of upper and lower jaws and a standard dental crown model at the edentulous part;
placing the standard dental crown model into a corresponding edentulous position in the upper and lower jaw occlusion model to obtain a designed dental crown model;
performing expansion treatment on all the designed dental crown models, and trimming each designed dental crown model in sequence to remove expansion overlapped parts of the designed dental crown models and other designed dental crown models which are not subjected to trimming operation;
expanding the upper and lower jaw occlusion model, and trimming the designed dental crown model to remove an expansion superposition part of the designed dental crown model and adjacent teeth;
Identifying a triangular surface patch and a pointed triangular surface patch of a high refraction edge in the designed dental crown model, and marking;
deleting the triangular patch and the pointed triangular patch where the marked high refraction edge is located;
repairing the hole in the designed dental crown model;
the identifying and marking of the triangular surface patch where the high refraction edge is located in the designed dental crown model further comprises:
traversing each first edge on each triangular patch c of the designed dental crown model, and obtaining another triangular patch n adjacent to the first edge;
calculating an included angle alpha of a normal between the triangular patch c and the triangular patch n;
when the numerical value of the included angle alpha is larger than a preset first included angle threshold value, marking the triangular patch c and the triangular patch n as triangular patches with high refraction edges;
the identifying and marking of the sharp triangular patch in the designed dental crown model further comprises:
traversing each vertex p on the designed dental crown model and each second edge connected with the vertex p;
calculating an included angle beta between the second edge and the normal of the vertex p, wherein if the included angle beta is an obtuse angle, a complementary angle of the included angle beta is taken as a new included angle beta;
And when the numerical values of at most two included angles in all included angles beta related to the vertex p are larger than a preset second included angle threshold value, all the triangular patches containing the vertex p are marked as pointed triangular patches.
2. The digital dental crown design method according to claim 1, wherein the expanding all of the design dental crown models further comprises:
generating distance field data for all of the designed crown models;
and extracting an expansion isosurface from the distance field data based on an isosurface generating algorithm, wherein the distance value of the expansion isosurface from the designed dental crown model is a preset expansion gap value.
3. The digital crown design method according to claim 2, wherein the generating distance field data for all of the design crown models further comprises:
respectively generating an outer bounding box for each designed crown model, and respectively moving six faces of the outer bounding box outwards for a first preset distance to obtain a first cubic area corresponding to each designed crown model;
generating a three-dimensional cubic grid based on the first cubic region;
traversing each grid point a in the three-dimensional cubic grid, calculating the shortest distance value d between the grid point a and the designed dental crown model, and judging whether the grid point a is inside or outside the designed dental crown model;
Defining the distance value d as a positive value when the grid point a is outside the designed crown model; defining the distance value d as a negative value when the grid point a is inside the designed dental crown model; defining a distance value d of 0 when the grid point a is located on the surface of the designed crown model; and taking the distance value d as a scalar of the grid point a to obtain three-dimensional cubic grid data with the scalar, namely the distance field data of the designed dental crown model.
4. The digital dental crown design method according to claim 1, wherein the expanding the upper and lower jaw occlusion models, trimming the design dental crown model to remove an expanded overlapping portion of the design dental crown model with an adjacent tooth, further comprises:
respectively generating outer bounding boxes for the designed dental crown model, and respectively moving six surfaces of the outer bounding boxes outwards for a second preset distance to obtain a second cubic area of the designed dental crown model;
trimming the occlusion model of the upper jaw and the lower jaw, and reserving a superposed part of the occlusion model of the upper jaw and the lower jaw and the second cubic area to obtain an area adjacent tooth model;
and performing expansion treatment on the region adjacent tooth model, and trimming the designed dental crown model to remove the expansion overlapped part of the adjacent tooth in the designed dental crown model.
5. The digital crown design method according to claim 1, further comprising, after the identifying and marking the triangular and sharp triangular patches in the design crown model on which the highly refractive edges are located:
expanding the ranges of the triangular patch where the high refraction edge is located and the pointed triangular patch and marking;
wherein, expand the range of the triangle patch that the high refraction limit is located and mark, further include:
traversing the remaining first edges of the triangular patch identified as the highly refractive edge and taking another triangular patch n' adjacent to the first edge;
calculating an included angle of a normal between a triangular patch where the high refraction edge is located and the triangular patch n';
when the included angle is larger than a preset first included angle threshold value, identifying the triangular patch n' as a triangular patch where the high refraction edge is located;
wherein expanding the range of the cusp-shaped triangular patch and marking further comprises:
traversing the other vertexes p 'marked as the pointed triangular patch and each second edge connected with the vertexes p';
calculating an included angle beta ' between the second edge and the normal of the vertex p ', wherein if the included angle beta ' is an obtuse angle, a complementary angle of the included angle beta ' is taken as a new included angle beta ';
And when the numerical values of at most two included angles in all included angles beta ' related to the vertex p ' are greater than a preset second included angle threshold value, marking the rest triangular patches including the vertex p ' as pointed triangular patches.
6. The digital dental crown design method according to claim 1, further comprising after the repairing the hole in the design dental crown model:
manually smoothing selected regions in the designed crown model based on a triangular face smoothing algorithm.
7. The digital crown design method according to any one of claims 1 to 6, wherein the acquiring the maxillomandibular occlusion model and the standard crown model at the edentulous further comprises:
acquiring an upper jaw three-dimensional model and a lower jaw three-dimensional model which are scanned independently and CBCT data shot in a bite state;
and registering the upper jaw three-dimensional model and the lower jaw three-dimensional model based on the CBCT data to obtain the upper and lower jaw occlusion model.
8. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor, when executing the program, carries out the steps of the digital crown design method according to any of the claims 1 to 7.
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| JP2003516168A (en) * | 1999-04-29 | 2003-05-13 | ダイレクトクラウン・エルエルシー | Hourglass-shaped temporary crown and long-term provisional crown with occlusal contour |
| CN105266905A (en) * | 2014-07-17 | 2016-01-27 | 上海时代天使医疗器械有限公司 | Tooth correctional system suitable for mixed dentition and manufacturing method |
| CN108403234A (en) * | 2018-02-26 | 2018-08-17 | 北京正齐口腔医疗技术有限公司 | Arrange tooth method and device |
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| US9168114B2 (en) * | 2013-10-17 | 2015-10-27 | B & D Dental Corp. | Method of making a dental prosthesis |
| KR101953341B1 (en) * | 2017-09-20 | 2019-03-04 | 오스템임플란트 주식회사 | Crown digital design method for processing overlapped region, apparatus, and recording medium thereof |
| CN111563900B (en) * | 2020-04-01 | 2023-04-25 | 正雅齿科科技(上海)有限公司 | Method for repairing digital dental crown model and designing and preparing shell-shaped dental appliance |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003516168A (en) * | 1999-04-29 | 2003-05-13 | ダイレクトクラウン・エルエルシー | Hourglass-shaped temporary crown and long-term provisional crown with occlusal contour |
| CN105266905A (en) * | 2014-07-17 | 2016-01-27 | 上海时代天使医疗器械有限公司 | Tooth correctional system suitable for mixed dentition and manufacturing method |
| CN108403234A (en) * | 2018-02-26 | 2018-08-17 | 北京正齐口腔医疗技术有限公司 | Arrange tooth method and device |
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