Tooth preparation depth guiding method and system based on mixed reality technology

Abstract

The invention provides a tooth preparation depth guiding method and system based on a mixed reality technology, relates to the technical field of stomatology, and solves the problems that the preparation depth is difficult to accurately control and the manufacturing cost of a guiding tool is high. The method comprises the following steps: acquiring a digital dentition model M1 corresponding to an intraoral dentition of a patient, designing and manufacturing a digital diagnosis wax pattern M2, and inputting the digital diagnosis wax pattern M2 into AR glasses to form a virtual diagnosis wax pattern M3; acquiring and updating a real dentition model M4 corresponding to the intraoral dentition of the patient in real time through AR glasses, and forming an intraoral live-action dentition model M5 in an AR glasses coordinate system; performing model matching of the wax pattern M3 and the model M5, projecting the wax pattern M3 and the model M5 into AR glasses, placing a measuring rod on the surface of a preparation body, observing the distance between the surface of the model M5 and the contour of the wax pattern M3, and evaluating whether the tooth preparation depth meets a preset depth requirement or not; the tooth preparation depth of tooth preparation is accurately guided, and the overall quality and efficiency of tooth preparation are improved.

Description

Technical Field

[0001] The present invention relates to the field of oral medicine technology, and is applied to tooth preparation process, and specifically to a tooth preparation depth guidance method and system based on mixed reality technology. Background Art

[0002] In the process of oral restoration, in order to provide the necessary space for the restoration, the restoration of tooth defects usually requires tooth preparation. This process requires the doctor to accurately control the preparation depth to ensure that the restoration can be properly positioned and maintain good function and aesthetic effects. However, the guidance of tooth preparation depth has always been a difficult and hot issue in restoration.

[0003] The guidance techniques for tooth preparation depth mainly include relying on the doctor's subjective experience, using the needle diameter assessment, and using the tooth preparation depth guide. Although these methods have their own advantages, they also have obvious shortcomings.

[0004] First, the method that relies on the doctor's personal experience lacks precise quantitative standards during the operation, which makes it difficult to control the depth of tooth preparation and may lead to problems such as too shallow or too deep preparation.

[0005] Secondly, although the assessment of preparation depth by the needle diameter provides a certain reference, its accuracy is limited due to the poor correlation between the needle and the actual cutting depth, and this method only considers the status of the existing teeth and ignores the needs of future restorations.

[0006] Furthermore, although the preparation depth guide combines the shape of the existing teeth with the shape of the future restoration, thereby providing more accurate preparation depth guidance, its production process is complicated and not only time-consuming but also increases production costs. This is a considerable challenge in the modern medical environment that pursues high efficiency and low cost.

[0007] With the development of oral restoration technology, precision and minimally invasive techniques have become a trend. Before performing tooth preparation, doctors usually need to make a model of the patient's dentition, and the dental technician will make an aesthetic diagnostic wax model based on this model to simulate the appearance of the future restoration. Despite this, the existing preparation depth guidance method still cannot fully meet the requirements of precision and minimally invasive techniques, especially in terms of ensuring the preparation depth while reducing damage to healthy tooth tissue. Therefore, it is urgent to develop a new method that can both improve the accuracy of tooth preparation and reduce production costs to meet the needs of the development of modern oral restoration technology. Summary of the invention

[0008] The purpose of the present invention is to solve the problem that the tooth preparation depth is difficult to accurately control and the cost of guiding tools is high in the prior art, and therefore a tooth preparation depth guidance method and system based on mixed reality technology is proposed. Since the spatial position relationship of the aesthetic diagnostic wax-up can be used to guide the tooth preparation depth of tooth preparation, the present invention implements the spatial coupling of the virtual diagnostic wax-up and the intraoral dentition model based on mixed reality technology, thereby accurately guiding the tooth preparation depth of tooth preparation and improving the overall quality and efficiency of tooth preparation.

[0009] The present invention adopts the following technical solutions to achieve the purpose: A tooth preparation depth guidance method based on mixed reality technology comprises the following steps: S1, obtaining a digital dental arch model M1 corresponding to the patient's dental arch, and designing and producing a digital diagnostic wax-up model M2 based on the digital dental arch model M1; S2, inputting the digital diagnostic wax-up model M2 into the AR glasses to form a virtual diagnostic wax-up model M3 in the AR glasses coordinate system; S3, during tooth preparation, the real dental model M4 corresponding to the patient's dental arch is obtained and updated in real time through AR glasses to form a real-life dental model M5 in the AR glasses coordinate system; S4, performing model matching on the virtual diagnostic wax-up model M3 and the intraoral real-life dental arch model M5, so that the spatial positions of the two in the AR glasses coordinate system match each other; S5. Place the measuring rod vertically on the surface of the preparation, and use AR glasses to observe the distance between the surface of the real-life dental model M5 and the outline of the virtual diagnostic wax model M3, to evaluate whether the depth of tooth preparation meets the preset depth requirement, and to guide the depth of tooth preparation.

[0010] Furthermore, in step S2, a first positioning mark is set on the virtual diagnostic wax model M3; in step S3, a second positioning mark is set on the intraoral real-life dental arch model M5; after completing real-time model matching based on the first positioning mark and the second positioning mark, a real-time registered fusion image is obtained; the real-time registered fusion image is projected into the eyepiece of the AR glasses for observation by the operator, and the time series images acquired by the camera of the AR glasses and the tracking device are sequentially matched with each other to achieve real-time tracking.

[0011] Specifically, the positions of the first positioning mark on the virtual diagnostic wax-up model M3 and the second positioning mark on the intraoral real-life dentition model M5 are both set on the adjacent teeth of the abutment teeth in the intraoral dentition of the patient, and the number of the set marks is not less than 3; According to the camera and tracking device of the AR glasses, a second positioning mark is set on the real-life dental arch model M5 formed in the mouth after each frame is shot, and the second positioning mark is fitted with the first positioning mark on the virtual diagnostic wax type M3 to achieve registration; the registration algorithm adopts the iterative closest point algorithm ICP, and by executing iterative convergence, the first positioning mark and the second positioning mark are overlapped in the preset overlapping block, thereby achieving model matching between the virtual diagnostic wax type M3 and the real-life dental arch model M5 in the mouth.

[0012] The present invention also provides a tooth preparation depth guidance system based on mixed reality technology, the system having a computer, the computer being configured with a central processing unit and a memory, the memory storing a computer program; the system also comprising AR glasses, the AR glasses being communicatively connected to the computer, the computer program implementing the steps of the aforementioned tooth preparation depth guidance method based on mixed reality technology when executed by the central processing unit, and projecting a model-matched virtual diagnostic wax model M3 and an intraoral real-life dental arch model M5 in the eyepiece of the AR glasses.

[0013] In summary, due to the adoption of this technical solution, the beneficial effects of the present invention are as follows: The present invention achieves spatial coupling between the aesthetic diagnostic wax-up model and the intraoral dentition model by introducing mixed reality technology, thereby accurately guiding the preparation depth of tooth preparation. Specifically, after wearing AR glasses, the dentist can project the outline of the diagnostic wax-up model onto the glasses in a combination of virtual and real ways, so that the outline of the diagnostic wax-up model can be intuitively displayed on the abutment teeth. This visual guidance method not only improves the accuracy of the tooth preparation process, but also significantly reduces various problems caused by improper preparation depth.

[0014] Compared with the prior art, the accuracy of the present invention has been improved. Through mixed reality technology, the positional relationship between the virtual diagnostic wax model and the actual teeth is mapped in real time, so that the tooth preparation depth can be accurately controlled, avoiding the problem of inappropriate restorations caused by too deep or too shallow preparation. The method of the present invention no longer relies on traditional silicone rubber guides or other physical guides, reducing the materials and time required to make the guides, greatly reducing production costs. In addition, the use of AR glasses for visual guidance simplifies the tooth preparation process and improves work efficiency. Dentists can focus more on the operation itself and reduce errors caused by manual operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The overall process diagram of the method of the present invention is briefly described; Figure 2 It is a schematic diagram of the overall structure of the system of the present invention; Figure 3This is a schematic diagram of the application of the present invention in the depth guidance process of tooth preparation. DETAILED DESCRIPTION

[0016] In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0017] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example 1 A tooth preparation depth guidance method based on mixed reality technology. Figure 1 The overall process of the method is briefly described in FIG. 1 , which can be viewed simultaneously. The steps of the method are summarized as follows: S1, obtaining a digital dental arch model M1 corresponding to the patient's dental arch, and designing and producing a digital diagnostic wax-up model M2 based on the digital dental arch model M1; S2, inputting the digital diagnostic wax-up model M2 into the AR glasses to form a virtual diagnostic wax-up model M3 in the AR glasses coordinate system; S3, during tooth preparation, the real dental model M4 corresponding to the patient's dental arch is obtained and updated in real time through AR glasses to form a real-life dental model M5 in the AR glasses coordinate system; S4, performing model matching on the virtual diagnostic wax-up model M3 and the intraoral real-life dental arch model M5, so that the spatial positions of the two in the AR glasses coordinate system match each other; S5. Place the measuring rod vertically on the surface of the preparation, and use AR glasses to observe the distance between the surface of the real-life dental model M5 and the outline of the virtual diagnostic wax model M3, to evaluate whether the depth of tooth preparation meets the preset depth requirement, and to guide the depth of tooth preparation.

[0019] This embodiment will introduce the details of each step in detail according to the above step sequence.

[0020] First, in step S1, an intraoral scanner can be used to scan the patient's intraoral dentition, or a model scanner can be used to scan a physical dentition model made based on the patient's intraoral dentition to obtain scan data; based on the scan data, three-dimensional reconstruction is performed using reverse engineering software such as Geomagic to obtain a digital dentition model M1 corresponding to the patient's intraoral dentition.

[0021] Then, using the functional aesthetic analysis technology in dental design software such as EXOCAD, the corresponding digital diagnostic wax model M2 is designed and produced based on the digital dentition model M1.

[0022] In this embodiment, the data types of the digital dental arch model M1 and the real dental arch model M4 are both three-dimensional point cloud data.

[0023] In step S3 of this embodiment, the operator observes the patient's dental arch through the eyepiece of the AR glasses, and the camera of the AR glasses cooperates with the tracking device to obtain and update the real dental arch model M4 in real time, and form a corresponding real-life dental arch model M5 in the mouth. The AR glasses are worn on the operator's head, and the camera can be a common AR glasses configuration camera on the market. The camera-based visual SLAM algorithm can update the real dental arch model M4 and the corresponding real-life dental arch model M5 in real time. The visual SLAM algorithm is a well-known technology in the field of computer vision and will not be described in detail. The tracking device used here can be implemented in one or more combinations of infrared positioning cameras, optical positioning cameras, or electromagnetic induction devices.

[0024] The following is a detailed description of the model matching process between the virtual diagnostic wax-up model M3 and the intraoral real-life dentition model M5 in the method of this embodiment.

[0025] As a preferred method, in step S2, a first positioning mark is set on the virtual diagnostic wax model M3; in step S3, a second positioning mark is set on the intraoral real-life dental arch model M5; in step S4, after completing real-time model matching based on the first positioning mark and the second positioning mark, a real-time registration and fusion image is obtained; the real-time registration and fusion image is projected into the eyepiece of the AR glasses for observation by the operator, and the time series images acquired by the camera of the AR glasses and the tracking device are sequentially matched to each other to achieve real-time tracking.

[0026] Specifically, in this embodiment, the positions of the first positioning mark on the virtual diagnostic wax-up model M3 and the second positioning mark on the intraoral real-life dental arch model M5 are both set on the adjacent teeth of the abutment teeth in the patient's intraoral dental arch, and the number of settings is not less than 3.

[0027] In this embodiment, based on the camera and tracking device of the AR glasses, a second positioning mark is set on the corresponding intraoral real-life dental arch model M5 formed after each frame is shot, and the second positioning mark is fitted with the first positioning mark on the virtual diagnostic wax type M3 to achieve registration; the registration algorithm adopts the iterative closest point algorithm ICP, which is used to align the known parts of the three-dimensional body. By executing iterative convergence, the first positioning mark and the second positioning mark are overlapped in the preset overlapping block, thereby achieving model matching between the virtual diagnostic wax type M3 and the intraoral real-life dental arch model M5.

[0028] In addition to the model matching process of the preferred method described above, this embodiment also introduces an alternative method to achieve model matching, namely, through a pattern recognition algorithm, model matching is performed based on the surface curvature of both the virtual diagnostic wax model M3 and the intraoral real-life dental model M5, or the characteristic geometric shapes of the two.

[0029] In this embodiment, the projection of the virtual diagnostic wax model M3 in the AR glasses can be accurately integrated with the image of the intraoral real-life dental model M5 obtained during the operation, so that the operator can "perspectively" observe the outline of the virtual diagnostic wax model M3 during the operation. Therefore, in step S5, according to the operator's observation needs, the transparency of the image projection of the virtual diagnostic wax model M3 in the eyepiece of the AR glasses can be changed, and the interactive method of changing the transparency can be achieved by the operator dragging a slider.

[0030] Example 2 On the basis of Example 1, this embodiment provides a tooth preparation depth guidance system based on mixed reality technology, the system having a computer, the computer being configured with a central processing unit and a memory, the memory storing a computer program; the system also includes AR glasses, the AR glasses are communicatively connected to the computer, and the computer program, when executed by the central processing unit, implements the steps of the tooth preparation depth guidance method based on mixed reality technology as described in Example 1, and projects a model-matched virtual diagnostic wax model M3 and an intraoral real-life dental arch model M5 in the eyepiece of the AR glasses.

[0031] Figure 2 A schematic diagram of the logical structure of the above system is given, showing the relationship between the various components and the participation of operators and patients. Figure 2In the figure, mark 1 represents a computer; mark 2 represents the processing diagram of the central processing unit; mark 3 represents the first digital dental model M1; mark 4 represents the virtual diagnostic wax-up model M3 with the first positioning mark; mark 5 represents the virtual diagnostic wax-up model M3 and the real dental model M5 in the mouth after model matching; mark 6 represents AR glasses; mark 7 represents the real dental model M4 obtained through AR glasses; mark 8 represents the model matching diagram seen by the operator through the projection of AR glasses; mark 9 represents the operator; mark 10 represents the patient. Figure 2 The overall functional characteristics of the system in this embodiment can be better understood by referring to the schematic diagram of FIG.

[0032] The core of the system in this embodiment is the central processing unit. The central processing unit designs and produces a digital diagnostic wax-up model M2 based on the digital dentition model M1, and transmits it to the AR glasses to form a virtual diagnostic wax-up model M3 in the AR glasses coordinate system, and can attach a first positioning mark. The central processing unit also processes the real dentition model M4 from the AR glasses to form an intraoral real-life dentition model M5, which can be matched with the virtual diagnostic wax-up model M3 by attaching a second positioning mark, and the real-time registration fusion image is finally transmitted to the AR glasses for the operator to observe.

[0033] In this embodiment, combined with Figure 3 An example of the description is as follows: Figure 3 In the figure, mark 11 represents the physical prepared abutment; mark 12 represents the outline of the virtual diagnostic wax-up model M3, and its dotted line in the figure is the outline boundary line; mark 13 represents the depth-fixing needle; mark 14 represents the measuring rod.

[0034] Combination Figure 3 And the enlarged cross-section diagram, specifically explained as follows: Through the AR glasses, the operator can observe the patient's physical prepared abutment teeth, the outline of the virtual diagnostic wax model M3 that fits the physical prepared abutment teeth, and the depth-setting needle during the operation. Taking the implementation of the porcelain veneer tooth preparation process as an example, the operator vertically immerses the depth-setting needle into the fixed-depth hole prepared on the abutment tooth surface (not shown in the figure), and evaluates whether the preparation depth of the tooth preparation reaches the designed depth by measuring the immersion depth of the depth-setting needle within the outline of the virtual diagnostic wax model M3. Similarly, after tooth preparation, the operator can also effectively evaluate the preparation depth of the tooth preparation by measuring the depth of the fixed-depth measuring rod immersed in the virtual diagnostic wax model M3.

Claims

1. A tooth preparation depth guidance method based on mixed reality technology, characterized in that: The method comprises the following steps: S1, obtaining a digital dental arch model M1 corresponding to the patient's dental arch, and designing and producing a digital diagnostic wax-up model M2 based on the digital dental arch model M1; S2, inputting the digital diagnostic wax-up model M2 into the AR glasses to form a virtual diagnostic wax-up model M3 in the AR glasses coordinate system; S3, during tooth preparation, the real dental model M4 corresponding to the patient's dental arch is obtained and updated in real time through AR glasses to form a real-life dental model M5 in the AR glasses coordinate system; S4, performing model matching on the virtual diagnostic wax-up model M3 and the intraoral real-life dental arch model M5, so that the spatial positions of the two in the AR glasses coordinate system match each other; S5. Place the measuring rod vertically on the surface of the preparation, and use AR glasses to observe the distance between the surface of the real-life dental model M5 and the outline of the virtual diagnostic wax model M3, to evaluate whether the depth of tooth preparation meets the preset depth requirement, and to achieve depth guidance for tooth preparation.

2. The tooth preparation depth guidance method based on mixed reality technology according to claim 1, characterized in that: In step S1, an intraoral scanner is used to scan the patient's dentition, or a model scanner is used to scan a physical dentition model made based on the patient's dentition to obtain scan data; based on the scan data, three-dimensional reconstruction is performed using reverse engineering software to obtain a digital dentition model M1 corresponding to the patient's dentition.

3. The tooth preparation depth guidance method based on mixed reality technology according to claim 2, characterized in that: Using the functional aesthetic analysis technology in the dental design software, the corresponding digital diagnostic wax-up model M2 was designed and produced based on the digital dentition model M1.

4. The tooth preparation depth guidance method based on mixed reality technology according to claim 1, characterized in that: The data types of the digital dental arch model M1 and the real dental arch model M4 are both three-dimensional point cloud data.

5. The tooth preparation depth guidance method based on mixed reality technology according to claim 1, characterized in that: In step S3, the operator observes the dentition in the patient's mouth through the eyepiece of the AR glasses, and the camera of the AR glasses cooperates with the tracking device to obtain and update the real dentition model M4 in real time, thereby forming a corresponding real-life dentition model M5 in the mouth.

6. The tooth preparation depth guidance method based on mixed reality technology according to claim 1, characterized in that: In step S2, a first positioning mark is set on the virtual diagnostic wax model M3; in step S3, a second positioning mark is set on the intraoral real-life dental arch model M5; in step S4, after completing real-time model matching based on the first positioning mark and the second positioning mark, a real-time registration and fusion image is obtained; the real-time registration and fusion image is projected into the eyepiece of the AR glasses for observation by the operator, and the corresponding matching process is performed on the time series images obtained by the camera of the AR glasses and the tracking device in turn to achieve real-time tracking.

7. The tooth preparation depth guidance method based on mixed reality technology according to claim 6, characterized in that: The positions of the first positioning mark on the virtual diagnostic wax-up model M3 and the second positioning mark on the intraoral real-life dentition model M5 are both set on the adjacent teeth of the abutment teeth in the intraoral dentition of the patient, and the number of the settings is not less than 3; According to the camera and tracking device of the AR glasses, a second positioning mark is set on the real-life dental arch model M5 formed in the mouth after each frame is shot, and the second positioning mark is fitted with the first positioning mark on the virtual diagnostic wax type M3 to achieve registration; the registration algorithm adopts the iterative closest point algorithm ICP, and by executing iterative convergence, the first positioning mark and the second positioning mark are overlapped in the preset overlapping block, thereby achieving model matching between the virtual diagnostic wax type M3 and the real-life dental arch model M5 in the mouth.

8. The tooth preparation depth guidance method based on mixed reality technology according to claim 1, characterized in that: In the model matching process of step S4, model matching is performed based on the surface curvatures of the virtual diagnostic wax-up model M3 and the intraoral real-life dental arch model M5, or their characteristic geometric shapes, through a pattern recognition algorithm.

9. The tooth preparation depth guidance method based on mixed reality technology according to claim 1, characterized in that: In step S5, the transparency of the image projection of the virtual diagnostic wax-up model M3 in the eyepiece of the AR glasses is changed according to the operator's observation requirements.

10. A tooth preparation depth guidance system based on mixed reality technology, the system comprising a computer, the computer being configured with a central processing unit and a memory, the memory being stored with a computer program; characterized in that: The system also includes AR glasses, which are communicatively connected to the computer. When the computer program is executed by the central processing unit, the steps of the tooth preparation depth guidance method based on mixed reality technology as described in claim 1 are implemented, and a virtual diagnostic wax model M3 and an intraoral real-life dental arch model M5 after model matching are projected in the eyepiece of the AR glasses.

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