Artificial mark structure for intraoral scanning of edentulous jaw and intraoral scanning method thereof

Abstract

The invention discloses an artificial mark structure for oral scanning of an edentulous jaw and an oral scanning method of the artificial mark structure. The artificial mark structure comprises a patch layer, a bonding layer and a mark body which are sequentially arranged from bottom to top. The scanning method comprises the following steps: arranging an artificial mark structure at the top of an alveolar ridge of an edentulous jaw; scanning the palate area of the edentulous jaw of the upper jaw according to an S-shaped path; scanning the alveolar ridge palatal side of the edentulous jaw of the upper jaw according to the contour of the alveolar ridge palatal side; scanning around the artificial mark structure at the top of the alveolar ridge of the edentulous jaw of the upper jaw according to a broken line path; scanning on an alveolar ridge cheek side of the edentulous jaw of the upper jaw according to the contour of the alveolar ridge cheek side; scanning around the artificial mark structure at the top of the alveolar ridge of the edentulous jaw of the lower jaw according to a broken line path; scanning the tongue side of the alveolar ridge of the edentulous jaw of the lower jaw according to the contour of the tongue side of the alveolar ridge; and scanning on an alveolar ridge cheek side of the edentulous jaw of the lower jaw according to an alveolar ridge cheek side contour. According to the method, the splicing error rate in the scanning process can be reduced, and meanwhile, the accuracy and precision of the scanned image are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oral scanning and restoration, and in particular relates to an artificial landmark structure for intraoral scanning of an edentulous jaw and an intraoral scanning method thereof. Background Art

[0002] With the development of computer-aided design and manufacturing (CAD / CAM) technology, fully digital restoration technology has been increasingly used in oral clinical practice. Fully digital restoration technology uses an intraoral scanner to obtain a digital impression of the patient's oral cavity, and then performs digital processing to finally produce an oral restoration. As the first step of digital restoration technology, the intraoral scanning method can effectively save restoration time and facilitate communication between physicians and technicians. It provides a new oral restoration method for patients with strong pharyngeal reflexes, difficulty opening their mouths, and other conditions that make it difficult to use traditional plaster impression methods. Different intraoral scanners use different scanning methods, including triangulation, optical coherence tomography, confocal microscopy, and active wavefront sampling. The scanning accuracy of these methods varies, but is within the clinically acceptable range.

[0003] Edentulous jaw means that there are no natural teeth or tooth roots left in the entire dental arch. According to the results of the fourth national oral epidemiological survey, among the elderly aged 65-74, 86% have missing teeth, and the proportion of complete edentulism is 4.5%. It can be seen that there is a strong demand for improving the quality of life through edentulous restoration. In addition, the elderly group is often more likely to encounter difficulties such as conditioned reflex vomiting and limited mouth opening during the process of taking molds using the traditional plaster impression method, which makes the elderly group's experience in the relevant treatment process worse than that of the young and middle-aged groups, so it is necessary to intervene through the digital restoration process to improve this situation.

[0004] However, from a technical perspective, compared to complete or partially edentulous dentition, the morphology of the alveolar ridge of the edentulous jaw does not change significantly, the mucosal surface lacks anatomical landmarks that can be observed by intraoral scanners, the palatal vault is deep and narrow, and the labial and buccal vestibule mucosa is highly mobile, so it is difficult to perform intraoral scanning on the edentulous jaw, which is mainly reflected in the greatly increased stitching error rate during the scanning process and the reduced accuracy and precision of the scanned polygonal image after multiple corrections. Therefore, it is necessary to develop an artificial landmark structure for intraoral scanning of the edentulous jaw and its intraoral scanning method to improve the scanning accuracy of the edentulous jaw and improve the experience of oral patients, mainly the elderly, during edentulous restoration treatment.

[0005] The invention patent with application publication number CN115381576A discloses a method for measuring the accuracy deviation of an intraoral scanner, comprising the following steps: selecting a standard mandibular dentition superhard plaster model, preparing a series of circular concave marks No. 1-17 on the buccal and lingual surfaces of each tooth position of the plaster model as measurement points for the later model; using different intraoral scanners to scan the scanning model of the occlusal surface fixed red wax high-grade plate, the scanning path is 37 teeth lingual side - 37 teeth occlusal surface - 37 teeth buccal side - 36 teeth buccal side - anterior teeth labial surface - 47 teeth buccal side - 47 teeth lingual side - anterior teeth lingual surface - 35 teeth lingual side, in the process of scanning 36 teeth - 47 teeth, the red wax high-grade plate of the occlusal surface is not crossed, and the scanning start and end points are not connected; importing the scanned model data into Geomagic wrap In 2017, the digital model obtained by the model scanner was used as the reference model, and the model obtained by the intraoral scanner in the software was set as a floating model. The concave circles on the buccal surfaces of teeth 37, 36, 35, and 33 were used as landmarks to perform preliminary registration of the floating model and the reference model. The crown of tooth 37 in the floating model and the reference model was selected for automatic registration. By determining the centroid, a measurement landmark was generated at each concave circle. The distance between each measurement landmark on the reference model and the corresponding landmark of each group of experimental models was calculated to analyze the accuracy deviation of different intraoral scanners. This technical solution sets several model measurement points on the standard mandibular dentition model, which is mainly used to measure the accuracy deviation of different intraoral scanners. However, this technical solution is not suitable for scanning in the edentulous maxillary mouth. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides an artificial landmark structure for intraoral scanning of edentulous jaws, including a patch layer, an adhesive layer and a landmark body arranged in sequence from bottom to top, the patch layer and the adhesive layer are both circular, the landmark body is a truncated cone, and the side surface of the landmark body is composed of six identical arc surfaces.

[0007] The diameter of the patch layer is 3-5mm and the thickness is 0.2-0.4mm; the diameter of the adhesive layer is equal to the diameter of the patch layer, and the thickness of the adhesive layer is 0.05-0.1mm; the bottom diameter of the logo body is equal to the diameter of the adhesive layer, the top diameter of the logo body is 0.5 times the bottom diameter, and the height of the logo body is 0.4 times the bottom diameter; the overall shape of the logo body is a diamond-like structure, and its outer surface is matte treated.

[0008] The patch layer is composed of hyaluronic acid, corn starch and polyethylene glycol, wherein the mass percentage of each substance in the patch layer is 70-80wt% of hyaluronic acid, 10-20wt% of corn starch, and 5-10wt% of polyethylene glycol; the material of the adhesive layer is liquid carrageenan; and the material of the marker is resin.

[0009] In the present invention, the patch layer uses natural polymer hyaluronic acid as the skeleton material. As an unsulfated anionic glycosaminoglycan, hyaluronic acid can quickly absorb moisture and exhibit gel properties, thereby achieving bonding with the mucosal surface. Corn starch and polyethylene glycol are added to enhance adhesion. The patch layer has good film-forming properties, biocompatibility and certain biodegradability, and can adhere to the gums for a long time.

[0010] The sign is made of resin or resin-based composite materials, which is hard and not easy to deform; the outer surface of the sign is matte treated to avoid scanning errors due to transmission and reflection; the sign adopts a "diamond" structure in shape design, which enhances the characteristics of the sign itself while avoiding the appearance of edges and corners below 120° that are difficult to be recognized by scanners, further reducing the difficulty of recognition.

[0011] The adhesive layer is located between the patch layer and the logo body, that is, a thin layer of liquid carrageenan is coated, and the patch layer and the logo body are combined and then cooled and solidified to achieve adhesion between the patch layer and the logo body.

[0012] The present invention also provides an edentulous intraoral scanning method, using the artificial landmark structure for edentulous intraoral scanning, and comprising the following steps in order:

[0013] Step 1: According to the design requirements, artificial landmark structures are set on the top of the alveolar ridge of the maxillary edentulous jaw and the top of the alveolar ridge of the mandibular edentulous jaw respectively;

[0014] Step 2: Start the intraoral scanner, hold the scanning head, and make the scanning head scan continuously in the palate area of ​​the maxillary edentulous jaw in an S-shaped path;

[0015] Step 3: After the scanning of the palatal area of ​​the edentulous maxilla is completed, the scanning path of the scanning head is adjusted so that the scanning head continuously scans the palatal side of the alveolar ridge of the edentulous maxilla according to the palatal side contour of the alveolar ridge;

[0016] Step 4: After the palatal scanning of the alveolar ridge of the edentulous maxilla is completed, the scanning path of the scanning head is adjusted so that the scanning head continuously scans around the artificial landmark structure along a broken line path at the top of the alveolar ridge of the edentulous maxilla;

[0017] Step 5: After the scanning of the alveolar ridge top of the edentulous maxilla and the artificial landmark structure thereon is completed, the scanning path of the scanning head is adjusted so that the scanning head continuously scans the buccal side of the alveolar ridge of the edentulous maxilla according to the buccal contour of the alveolar ridge; after the buccal side of the alveolar ridge of the edentulous maxilla is scanned, a complete intraoral scanning model of the edentulous maxilla can be obtained;

[0018] Step 6: Place the scanning head on the top of the alveolar ridge of the edentulous mandible, and adjust the scanning path of the scanning head so that the scanning head continuously scans around the artificial landmark structure along a zigzag path on the top of the alveolar ridge of the edentulous mandible;

[0019] Step 7: After the top of the alveolar ridge of the edentulous mandible and the artificial landmark structure thereon are scanned, the scanning path of the scanning head is adjusted so that the scanning head continuously scans the lingual side of the alveolar ridge of the edentulous mandible according to the lingual side contour of the alveolar ridge;

[0020] Step 8: After the lingual scan of the alveolar ridge of the edentulous mandible is completed, adjust the scanning path of the scanning head so that the scanning head continuously scans the buccal side of the alveolar ridge of the edentulous mandible according to the buccal contour of the alveolar ridge; after the buccal scan of the alveolar ridge of the edentulous mandible is completed, a complete intraoral scan model of the edentulous mandible can be obtained.

[0021] Preferably, in step 1, five artificial landmark structures are set on the top of the alveolar ridge of the maxillary edentulous jaw, wherein the maxillary No. 1 artificial landmark structure is located at the top of the alveolar ridge of the upper anterior teeth; the maxillary No. 2 artificial landmark structure is located at the position of the first premolar on the left side of the original maxillary dentition corresponding to the alveolar ridge, and the area 2-3 mm forward or backward along the top of the alveolar ridge; the maxillary No. 3 artificial landmark structure is located at the position of the first premolar on the right side of the original maxillary dentition corresponding to the alveolar ridge, and the area along the top of the alveolar ridge. The area 2-3mm forward or backward from the top of the alveolar ridge; the maxillary No. 4 artificial landmark structure is located on the alveolar ridge corresponding to the position of the second molar on the left side of the original maxillary dentition, as well as in the area 2-3mm forward or backward along the top of the alveolar ridge, and in front of the left maxillary tuberosity; the maxillary No. 5 artificial landmark structure is located on the alveolar ridge corresponding to the position of the second molar on the right side of the original maxillary dentition, as well as in the area 2-3mm forward or backward along the top of the alveolar ridge, and in front of the right maxillary tuberosity.

[0022] In any of the above schemes, preferably, in step 1, five artificial landmark structures are set on the top of the alveolar ridge of the mandibular edentulous jaw, wherein the mandibular No. 1 artificial landmark structure is located at the top of the alveolar ridge of the lower front teeth; the mandibular No. 2 artificial landmark structure is located at the position of the first premolar on the left side of the original mandibular dentition corresponding to the alveolar ridge, and the area 2-3 mm forward or backward along the top of the alveolar ridge; the mandibular No. 3 artificial landmark structure is located at the position of the first premolar on the right side of the original mandibular dentition corresponding to the alveolar ridge, and the area 2-3 mm forward or backward along the top of the alveolar ridge; The mandibular No. 4 artificial landmark structure is located at the alveolar ridge corresponding to the position of the second molar on the left side of the original mandibular dentition, and at the area 2-3mm forward or backward along the top of the alveolar ridge, and in front of the left mandibular molar retropad; the mandibular No. 5 artificial landmark structure is located at the alveolar ridge corresponding to the position of the second molar on the right side of the original mandibular dentition, and at the area 2-3mm forward or backward along the top of the alveolar ridge, and in front of the right mandibular molar retropad.

[0023] In the present invention, five raised artificial landmark structures are symmetrically arranged along the top of the alveolar ridge of the edentulous jaw, so as to simulate the positioning function of the teeth to a certain extent. The five artificial landmark structures are kept at an appropriate distance, so that when the intraoral scanner scans along the alveolar ridge, two adjacent artificial landmark structures can appear in a scanned photo at the same time. At the same time, during the intraoral scanning process, the doctor can compare the scanned image displayed on the screen with the actual situation in the mouth. If a scanning blind area or a polygonal sparse area is found, the secondary scan can start from the adjacent artificial landmark structure and move to the scanning area to be supplemented. This solution avoids the intraoral scanner from being unable to identify the appropriate anatomical landmarks and causing incorrect splicing, thereby improving the scanning efficiency and scanning accuracy.

[0024] The spacing between the five artificial landmark structures should be controlled within a certain range, and their specific positions are as follows: For the maxillary edentulous jaw, the maxillary No. 1 artificial landmark structure is set about 7 mm in front of the midpoint of the incisor mastoid, that is, at the intersection of the central sagittal plane and the dental arch. The maxillary No. 2 artificial landmark structure and the maxillary No. 3 artificial landmark structure are set about 4 mm back from the midpoint of the incisor mastoid along the midline, and about 22 mm to the left and right of the central sagittal plane. The maxillary No. 4 artificial landmark structure and the maxillary No. 5 artificial landmark structure are set about 16 mm back from the midpoint of the incisor mastoid along the midline, and about 28 mm to the left and right of the central sagittal plane.

[0025] For the edentulous mandible, the mandibular No. 1 artificial landmark structure was set about 5 mm in front of the connection between the lingual frenulum and the floor of the mouth, that is, at the intersection of the midline and the mandibular alveolar ridge. The mandibular No. 2 artificial landmark structure and the mandibular No. 3 artificial landmark structure were set about 4 mm forward of the mandibular protuberance on the left and right sides, respectively. The mandibular No. 4 artificial landmark structure and the mandibular No. 5 artificial landmark structure were set about 6 mm forward of the retromolar pads on the left and right sides, respectively.

[0026] In any of the above solutions, preferably, in step 2, the method of continuously scanning the palate region of the edentulous maxilla with the scanning head in an S-shaped path comprises the following steps in chronological order:

[0027] Step 2.1: Hold the scanning head and place it at the front of the maxillary edentulous palate near the maxillary No. 1 artificial landmark structure. At this time, the maxillary No. 1 artificial landmark structure appears in the field of view of the intraoral scanner. This position is used as the starting point for scanning the maxillary edentulous palate area.

[0028] Step 2.2: Hold the scanning head and start from the starting point of the maxillary edentulous palate area scanning, first move the scanning head to the left side of the palate area, and then continuously scan from the front to the back of the palate area along an S-shaped path; in the process of scanning in the first complete transverse scanning area, the maxillary No. 2 artificial landmark structure and the maxillary No. 3 artificial landmark structure are simultaneously presented in the scanning model of the intraoral scanner; in the process of scanning in the third to fourth complete transverse scanning areas, the maxillary No. 4 artificial landmark structure and the maxillary No. 5 artificial landmark structure are simultaneously presented in the scanning model of the intraoral scanner;

[0029] Step 2.3: Holding the scanning head, continue scanning toward the posterior part of the palate along the S-shaped path until the right maxillary tuberosity is reached. At this time, at least 50% of the alveolar ridge is present in the scanning model of the intraoral scanner. This position is taken as the end point of the maxillary edentulous palate scan.

[0030] In any of the above schemes, preferably, in step 3, the method of continuously scanning the palatal side of the alveolar ridge of the edentulous maxilla with the scanning head according to the palatal side contour of the alveolar ridge comprises the following steps in chronological order:

[0031] Step 3.1: After the palatal scan of the edentulous maxilla is completed, the end point of the palatal scan of the edentulous maxilla is used as the starting point of the palatal scan of the edentulous maxilla alveolar ridge;

[0032] Step 3.2: Hold the scanning head and start from the starting point of the palatal scan of the maxillary edentulous alveolar ridge, and scan continuously along the palatal contour of the alveolar ridge until the end of the left maxillary tuberosity. This completes the correction of the palatal alveolar ridge. At this time, 60-70% of the alveolar ridge is presented in the scanning model of the intraoral scanner. This position is used as the end point of the palatal scan of the maxillary edentulous alveolar ridge.

[0033] In any of the above schemes, preferably, in step 4, the method of continuously scanning the top of the alveolar ridge of the edentulous maxilla by the scanning head along a broken line path around the artificial landmark structure comprises the following steps in order:

[0034] Step 4.1: After the palatal scan of the maxillary edentulous alveolar ridge is completed, the end point of the palatal scan of the maxillary edentulous alveolar ridge is used as the starting point of the scan of the maxillary edentulous alveolar ridge top and the artificial landmark structure thereon;

[0035] Step 4.2: Hold the scanning head and start from the top of the maxillary edentulous alveolar ridge and the starting point of the scanning of the artificial landmark structure on it, and scan continuously around the maxillary No. 4 artificial landmark structure, the maxillary No. 2 artificial landmark structure, the maxillary No. 1 artificial landmark structure, the maxillary No. 3 artificial landmark structure and the maxillary No. 5 artificial landmark structure in a broken line path at the top of the alveolar ridge; when the maxillary No. 4 artificial landmark structure is scanned, tilt the scanning head toward the maxillary No. 4 artificial landmark structure for scanning. At this time, the maxillary No. 4 artificial landmark structure and part of the alveolar ridge will appear in the scanning model of the intraoral scanner; wait for the maxillary No. 4 artificial landmark structure to be scanned. After the scanning of the maxillary landmark structure is completed, the scanning head is moved along the zigzag path toward the maxillary No. 2 artificial landmark structure while adjusting its inclination. In the process of moving the scanning head along the zigzag path, the maxillary No. 4 artificial landmark structure, the maxillary No. 4 artificial landmark structure, the maxillary No. 2 artificial landmark structure, and the maxillary No. 2 artificial landmark structure are sequentially presented in the scanning model of the intraoral scanner; when the maxillary No. 2 artificial landmark structure is scanned, the scanning head is tilted toward the maxillary No. 2 artificial landmark structure for scanning, and at this time, the maxillary No. 2 artificial landmark structure and part of the alveolar ridge are presented in the scanning model of the intraoral scanner; and so on;

[0036] Step 4.3: Holding the scanning head, continue scanning along the zigzag path around the artificial landmark structure at the top of the alveolar ridge until the left maxillary tuberosity is reached. At this time, the complete alveolar ridge is presented in the scanning model of the intraoral scanner. This position is used as the end point of the scan of the top of the maxillary edentulous alveolar ridge and the artificial landmark structure on it.

[0037] In any of the above schemes, preferably, in step 5, the method of continuously scanning the buccal side of the alveolar ridge of the edentulous maxilla with the scanning head according to the buccal side contour of the alveolar ridge comprises the following steps in chronological order:

[0038] Step 5.1: After the scanning of the top of the alveolar ridge of the edentulous maxilla and the artificial landmark structure thereon is completed, the end point of the scanning of the top of the alveolar ridge of the edentulous maxilla and the artificial landmark structure thereon is used as the starting point of the buccal scanning of the alveolar ridge of the edentulous maxilla;

[0039] Step 5.2: Hold the scanning head and start from the starting point of the buccal scan of the maxillary edentulous alveolar ridge, and continuously scan along the buccal contour of the alveolar ridge until the end of the position of the right maxillary tuberosity, thus completing the correction of the buccal alveolar ridge. At this time, the intraoral scanner presents a complete intraoral scan model of the maxillary edentulous jaw. This position is used as the end point of the buccal scan of the maxillary edentulous alveolar ridge.

[0040] In any of the above solutions, preferably, in step 6, the method of continuously scanning the top of the alveolar ridge of the edentulous mandible by the scanning head along a broken line path around the artificial landmark structure comprises the following steps in order:

[0041] Step 6.1: Hold the scanning head and place it on the top of the alveolar ridge on the right side of the edentulous mandible, and use this position as the starting point for scanning the top of the alveolar ridge and the artificial landmark structure on the edentulous mandible. Scan continuously along the mandibular No. 5 artificial landmark structure, mandibular No. 3 artificial landmark structure, mandibular No. 1 artificial landmark structure, mandibular No. 2 artificial landmark structure and mandibular No. 4 artificial landmark structure on the top of the alveolar ridge in a broken line path; when the position of the mandibular No. 5 artificial landmark structure is scanned, tilt the scanning head towards the mandibular No. 5 artificial landmark structure for scanning. At this time, the mandibular No. 5 artificial landmark structure and part of it appear in the scanning model of the intraoral scanner. alveolar ridge; after the scanning of the mandibular No. 5 artificial landmark structure is completed, the scanning head is moved along the zigzag path toward the mandibular No. 3 artificial landmark structure while adjusting the inclination of the scanning head. In the process of moving the scanning head along the zigzag path, the mandibular No. 5 artificial landmark structure, the mandibular No. 5 artificial landmark structure, the mandibular No. 3 artificial landmark structure, and the mandibular No. 3 artificial landmark structure are sequentially presented in the scanning model of the intraoral scanner; when the position of the mandibular No. 3 artificial landmark structure is scanned, the scanning head is tilted toward the mandibular No. 3 artificial landmark structure for scanning, and at this time, the mandibular No. 3 artificial landmark structure and part of the alveolar ridge are presented in the scanning model of the intraoral scanner; and so on;

[0042] Step 6.2: Holding the scanning head, continue to scan continuously around the artificial landmark structure at the top of the alveolar ridge in a zigzag path until the left mandibular molar retromolar pad is finished. At this time, the complete alveolar ridge is presented in the scanning model of the intraoral scanner. This position is used as the end point of the scan of the top of the mandibular edentulous alveolar ridge and the artificial landmark structure on it.

[0043] In any of the above schemes, preferably, in step 7, the method of continuously scanning the alveolar ridge lingual side of the edentulous mandible according to the alveolar ridge lingual side contour by the scanning head comprises the following steps in chronological order:

[0044] Step 7.1: After the scanning of the top of the alveolar ridge of the edentulous mandible and the artificial landmark structure thereon is completed, the end point of the scanning of the top of the alveolar ridge of the edentulous mandible and the artificial landmark structure thereon is used as the starting point of the lingual scanning of the alveolar ridge of the edentulous mandible;

[0045] Step 7.2: Hold the scanning head and start from the starting point of the lingual scan of the mandibular edentulous alveolar ridge, and continue scanning along the lingual contour of the alveolar ridge until the end of the position of the right mandibular molar back pad. This completes the correction of the lingual alveolar ridge. At this time, 60-70% of the alveolar ridge is presented in the scan model of the intraoral scanner. This position is used as the end point of the lingual scan of the mandibular edentulous alveolar ridge.

[0046] In any of the above solutions, preferably, in step eight, the method of continuously scanning the buccal side of the alveolar ridge of the edentulous mandible by the scanning head according to the buccal contour of the alveolar ridge comprises the following steps in chronological order:

[0047] Step 8.1: After the lingual scan of the alveolar ridge of the edentulous mandible is completed, the end point of the lingual scan of the alveolar ridge of the edentulous mandible is used as the starting point of the buccal scan of the alveolar ridge of the edentulous mandible;

[0048] Step 8.2: Hold the scanning head and start from the starting point of the buccal scan of the mandibular edentulous alveolar ridge, and continue scanning along the buccal contour of the alveolar ridge until the position of the left mandibular molar back pad is ended, thus completing the correction of the buccal alveolar ridge. At this time, the intraoral scanner presents a complete intraoral scan model of the mandibular edentulous jaw, and this position is used as the end point of the buccal scan of the mandibular edentulous alveolar ridge.

[0049] The artificial landmark structure for intraoral scanning of edentulous jaw and the intraoral scanning method thereof of the present invention have the following beneficial effects:

[0050] (1) The diamond-shaped artificial landmark structures protruding from the alveolar ridge of the edentulous mandible are arranged at appropriate intervals, playing a clear anatomical landmark role in terms of structural and color characteristics. At the same time, there are sufficient gaps between the artificial landmark structures to avoid scanning interference caused by occlusion.

[0051] (2) The artificial landmark structure on the alveolar ridge plays a positioning role. The artificial landmark structure and the intraoral scanning method can effectively reduce the time required for scanning, reduce the number of polygons in the scanning model, improve the scanning efficiency, and also improve the accuracy and precision of palate scanning.

[0052] (3) When the scanner is started, it can quickly identify the artificial landmark structure and the soft tissue information around it, reducing the common phenomenon in direct intraoral scanning where the image stitching cannot be started due to the inability to identify the edentulous jaw features.

[0053] (4) After the initial scan, the physician can conduct targeted general scanning starting from the adjacent artificial landmark structure in the scanning blind area or polygonal sparse area. This operation can effectively reduce the phenomenon of splicing the new image to the wrong position of the original image due to the loss of relative position relationship of the new image caused by the restart of the intraoral scanner during the second scan in direct intraoral scanning, thereby improving the scanning efficiency.

[0054] (5) The artificial landmark structure and the corresponding intraoral scanning method of the present invention help to avoid splicing errors in intraoral scanning of edentulous jaws. Through this technical solution, the clinical application of intraoral scanning of edentulous jaws can be promoted, and full digital technology can be applied to the restoration process of missing teeth. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A front view of a preferred embodiment of an artificial landmark structure for intraoral scanning of edentulous jaws according to the present invention;

[0056] Figure 2 for Figure 1 A top view of the artificial marking structure in the illustrated embodiment;

[0057] Figure 3 for Figure 1 A schematic diagram of the positions of five artificial landmark structures arranged on the alveolar ridge top of the edentulous maxilla in the embodiment shown, wherein the left position in the figure corresponds to the right position of the edentulous maxilla in the human oral cavity;

[0058] Figure 4 for Figure 1 A schematic diagram of the positions of five artificial landmark structures disposed on the alveolar ridge top of the edentulous mandible in the embodiment shown, wherein the left position in the figure corresponds to the right position of the edentulous mandible in the human oral cavity;

[0059] Figure 5 for Figure 1 A schematic diagram of the intraoral scanning path of the edentulous maxilla in the illustrated embodiment, wherein the left position in the figure corresponds to the right position of the edentulous maxilla in the human oral cavity;

[0060] Figure 6 for Figure 1 A schematic diagram of the intraoral scanning path of the edentulous mandible in the embodiment shown, where the left position in the figure corresponds to the right position of the edentulous mandible in the human oral cavity;

[0061] Figure 7 for Figure 1 Intraoral scan image of the edentulous maxilla with five artificial landmark structures set in the illustrated embodiment;

[0062] Figure 8 for Figure 1 Intraoral scan image of the edentulous mandible with five artificial landmark structures set in the embodiment shown;

[0063] Fig. 9 for Figure 1 The scanning result analysis diagrams of the maxillary edentulous jaw outside the mouth and inside the head model in the embodiment shown, wherein: (a) is a scanning time analysis diagram, (b) is an image quantity analysis diagram, (c) is a scanning correctness analysis diagram, and (d) is a scanning precision analysis diagram;

[0064] Fig.10 for Figure 1 The scanning result analysis diagrams of the mandibular edentulous jaw outside the mouth and inside the head model in the illustrated embodiment, wherein: (a) is a scanning time analysis diagram, (b) is an image quantity analysis diagram, (c) is a scanning correctness analysis diagram, and (d) is a scanning precision analysis diagram.

[0065] Notes in the figure:

[0066] 1-patch layer, 2-adhesive layer, 3-marker, 4-arc surface;

[0067] 5 - Maxillary No.1 artificial landmark structure, 6 - Maxillary No.2 artificial landmark structure, 7 - Maxillary No.3 artificial landmark structure, 8 - Maxillary No.4 artificial landmark structure, 9 - Maxillary No.5 artificial landmark structure, 10 - Right maxillary tuberosity, 11 - Left maxillary tuberosity;

[0068] 12 - Mandibular No.1 artificial landmark structure, 13 - Mandibular No.2 artificial landmark structure, 14 - Mandibular No.3 artificial landmark structure, 15 - Mandibular No.4 artificial landmark structure, 16 - Mandibular No.5 artificial landmark structure, 17 - Right mandibular retromolar pad, 18 - Left mandibular retromolar pad;

[0069] 19 - S-shaped path, 20 - Palatal contour of maxillary alveolar ridge, 21 - Zigzag path of maxillary alveolar ridge, 22 - Buccal contour of maxillary alveolar ridge, 23 - Zigzag path of mandibular alveolar ridge, 24 - Lingual contour of mandibular alveolar ridge, 25 - Buccal contour of mandibular alveolar ridge. Detailed implementation mode

[0070] In order to further understand the content of the present invention, the present invention will be elaborated in detail below in combination with specific embodiments.

[0071] Embodiment 1:

[0072] As Figure 1-2 shown, according to a preferred embodiment of the artificial landmark structure for intraoral scanning of edentulous jaws of the present invention, it includes a patch layer 1, an adhesive layer 2 and a marker body 3 arranged in sequence from bottom to top. The patch layer 1 and the adhesive layer 2 are both circular, the marker body 3 is frustum-shaped, and the side surface of the marker body 3 is composed of six identical arc surfaces 4.

[0073] The diameter of the patch layer is 4 mm and the thickness is 0.3 mm; the diameter of the adhesive layer is equal to the diameter of the patch layer, and the thickness of the adhesive layer is 0.08 mm; the bottom diameter of the marker body is equal to the diameter of the adhesive layer, the top diameter of the marker body is 0.5 times its bottom diameter, and the height of the marker body is 0.4 times its bottom diameter. The overall shape of the marker body is a diamond-shaped structure, and its outer surface is matte-treated.

[0074] The patch layer is composed of hyaluronic acid, corn starch and polyethylene glycol, and the mass percentages of each substance in the patch layer are: hyaluronic acid accounts for 75 wt%, corn starch accounts for 15 wt%, and polyethylene glycol accounts for 10 wt%; the material of the adhesive layer is liquid carrageenan; the material of the marker body is resin.

[0075] This embodiment also provides an intraoral scanning method for edentulous jaws, and its intraoral scanning path is as Figure 5 and Figure 6As shown, the intraoral scanning method uses the artificial landmark structure for intraoral scanning of edentulous jaws, and includes the following steps in order:

[0076] Step 1: According to the design requirements, artificial landmark structures are set on the top of the alveolar ridge of the maxillary edentulous jaw and the top of the alveolar ridge of the mandibular edentulous jaw respectively;

[0077] Step 2: Start the intraoral scanner, hold the scanning head, and make the scanning head scan continuously along the S-shaped path 19 in the palate area of ​​the edentulous maxilla;

[0078] Step 3: After the scanning of the palatal area of ​​the edentulous maxilla is completed, the scanning path of the scanning head is adjusted so that the scanning head continuously scans the palatal side of the alveolar ridge of the edentulous maxilla according to the palatal side contour of the maxillary alveolar ridge 20;

[0079] Step 4: After the palatal scanning of the alveolar ridge of the edentulous maxilla is completed, the scanning path of the scanning head is adjusted so that the scanning head continuously scans around the artificial landmark structure along the maxillary alveolar ridge zigzag path 21 at the top of the alveolar ridge of the edentulous maxilla;

[0080] Step 5: After the top of the alveolar ridge of the edentulous maxilla and the artificial landmark structure thereon are scanned, the scanning path of the scanning head is adjusted so that the scanning head continuously scans the buccal side of the alveolar ridge of the edentulous maxilla according to the buccal side contour 22 of the alveolar ridge of the edentulous maxilla; after the buccal side scanning of the alveolar ridge of the edentulous maxilla is completed, a complete intraoral scanning model of the edentulous maxilla can be obtained;

[0081] Step 6: placing the scanning head on the top of the alveolar ridge of the edentulous mandible, adjusting the scanning path of the scanning head, so that the scanning head continuously scans around the artificial landmark structure along the mandibular alveolar ridge zigzag path 23 at the top of the alveolar ridge of the edentulous mandible;

[0082] Step 7: After the top of the alveolar ridge of the edentulous mandible and the artificial landmark structure thereon are scanned, the scanning path of the scanning head is adjusted so that the scanning head continuously scans the lingual side of the alveolar ridge of the edentulous mandible according to the lingual side contour 24 of the mandibular alveolar ridge;

[0083] Step 8: After the lingual scan of the alveolar ridge of the edentulous mandible is completed, adjust the scanning path of the scanning head so that the scanning head continuously scans the buccal side of the alveolar ridge of the edentulous mandible according to the buccal contour 25 of the mandibular alveolar ridge; after the buccal scan of the alveolar ridge of the edentulous mandible is completed, a complete intraoral scan model of the edentulous mandible can be obtained.

[0084] In step 1, five artificial landmark structures are set on the top of the alveolar ridge of the edentulous maxilla. The qualitative positions of the five artificial landmark structures are as follows: Figure 3As shown, wherein: the maxillary No. 1 artificial landmark structure 5 is located at the middle top of the alveolar ridge of the upper anterior teeth; the maxillary No. 2 artificial landmark structure 6 is located at the position of the first premolar on the left side of the original maxillary dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position; the maxillary No. 3 artificial landmark structure 7 is located at the position of the first premolar on the right side of the original maxillary dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position; the maxillary No. 4 artificial landmark structure 8 is located at the position of the second molar on the left side of the original maxillary dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position, and is located in front of the left maxillary tubercle 11; the maxillary No. 5 artificial landmark structure 9 is located at the position of the second molar on the right side of the original maxillary dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position, and is located in front of the right maxillary tubercle 10.

[0085] Five artificial landmark structures were set on the alveolar ridge top of the edentulous mandible. The qualitative positions of the five artificial landmark structures are as follows: Figure 4 As shown, wherein: the mandibular No. 1 artificial landmark structure 12 is located at the middle top of the alveolar ridge of the lower front teeth; the mandibular No. 2 artificial landmark structure 13 is located at the position of the first premolar on the left side of the original mandibular dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position; the mandibular No. 3 artificial landmark structure 14 is located at the position of the first premolar on the right side of the original mandibular dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position; the mandibular No. 4 artificial landmark structure 15 is located at the position of the second molar on the left side of the original mandibular dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position, and is located in front of the left mandibular molar back pad 18; the mandibular No. 5 artificial landmark structure 16 is located at the position of the second molar on the right side of the original mandibular dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position, and is located in front of the right mandibular molar back pad 17.

[0086] In step 2, the method of continuously scanning the palate region of the edentulous maxilla with the scanning head in an S-shaped path includes the following steps in order:

[0087] Step 2.1: Hold the scanning head and place it at the front of the maxillary edentulous palate near the maxillary No. 1 artificial landmark structure. At this time, the maxillary No. 1 artificial landmark structure appears in the field of view of the intraoral scanner. This position is used as the starting point for scanning the maxillary edentulous palate area.

[0088] Step 2.2: Hold the scanning head and start from the starting point of the maxillary edentulous palate scanning, first move the scanning head to the left side of the palate, and then scan continuously from the front to the back of the palate along an S-shaped path; in the process of scanning in the first complete transverse scanning area, the maxillary No. 2 artificial landmark structure and the maxillary No. 3 artificial landmark structure are simultaneously presented in the scanning model of the intraoral scanner; in the process of scanning in the third to fourth complete transverse scanning areas, the maxillary No. 4 artificial landmark structure and the maxillary No. 5 artificial landmark structure are simultaneously presented in the scanning model of the intraoral scanner;

[0089] Step 2.3: Holding the scanning head, continue scanning toward the posterior part of the palate along the S-shaped path until the right maxillary tuberosity is reached. At this time, at least 50% of the alveolar ridge is present in the scanning model of the intraoral scanner. This position is taken as the end point of the maxillary edentulous palate scan.

[0090] In step 3, the method of continuously scanning the palatal side of the alveolar ridge of the edentulous maxilla with the scanning head according to the palatal side contour of the alveolar ridge includes the following steps in order:

[0091] Step 3.1: After the palatal scan of the edentulous maxilla is completed, the end point of the palatal scan of the edentulous maxilla is used as the starting point of the palatal scan of the edentulous maxilla alveolar ridge;

[0092] Step 3.2: Hold the scanning head and start from the starting point of the palatal scan of the maxillary edentulous alveolar ridge, and scan continuously along the palatal contour of the alveolar ridge until the end of the left maxillary tuberosity. This completes the correction of the palatal alveolar ridge. At this time, 60-70% of the alveolar ridge is presented in the scanning model of the intraoral scanner. This position is used as the end point of the palatal scan of the maxillary edentulous alveolar ridge.

[0093] In step 4, the method of continuously scanning the alveolar ridge top of the edentulous maxilla by the scanning head along a broken line path around the artificial landmark structure includes the following steps in order:

[0094] Step 4.1: After the palatal scan of the maxillary edentulous alveolar ridge is completed, the end point of the palatal scan of the maxillary edentulous alveolar ridge is used as the starting point of the scan of the maxillary edentulous alveolar ridge top and the artificial landmark structure thereon;

[0095] Step 4.2: Hold the scanning head and start from the top of the maxillary edentulous alveolar ridge and the starting point of the scanning of the artificial landmark structure on it, and scan continuously around the maxillary No. 4 artificial landmark structure, the maxillary No. 2 artificial landmark structure, the maxillary No. 1 artificial landmark structure, the maxillary No. 3 artificial landmark structure and the maxillary No. 5 artificial landmark structure in a broken line path at the top of the alveolar ridge; when the maxillary No. 4 artificial landmark structure is scanned, tilt the scanning head toward the maxillary No. 4 artificial landmark structure for scanning. At this time, the maxillary No. 4 artificial landmark structure and part of the alveolar ridge will appear in the scanning model of the intraoral scanner; wait for the maxillary No. 4 artificial landmark structure to be scanned. After the scanning of the maxillary landmark structure is completed, the scanning head is moved along the zigzag path toward the maxillary No. 2 artificial landmark structure while adjusting its inclination. In the process of moving the scanning head along the zigzag path, the maxillary No. 4 artificial landmark structure, the maxillary No. 4 artificial landmark structure, the maxillary No. 2 artificial landmark structure, and the maxillary No. 2 artificial landmark structure are sequentially presented in the scanning model of the intraoral scanner; when the maxillary No. 2 artificial landmark structure is scanned, the scanning head is tilted toward the maxillary No. 2 artificial landmark structure for scanning, and at this time, the maxillary No. 2 artificial landmark structure and part of the alveolar ridge are presented in the scanning model of the intraoral scanner; and so on;

[0096] Step 4.3: Holding the scanning head, continue scanning along the zigzag path around the artificial landmark structure at the top of the alveolar ridge until the left maxillary tuberosity is reached. At this time, the complete alveolar ridge is presented in the scanning model of the intraoral scanner. This position is used as the end point of the scan of the top of the maxillary edentulous alveolar ridge and the artificial landmark structure on it.

[0097] In step 5, the method of continuously scanning the buccal side of the alveolar ridge of the edentulous maxilla with the scanning head according to the buccal side contour of the alveolar ridge includes the following steps in order:

[0098] Step 5.1: After the scanning of the top of the alveolar ridge of the edentulous maxilla and the artificial landmark structure thereon is completed, the end point of the scanning of the top of the alveolar ridge of the edentulous maxilla and the artificial landmark structure thereon is used as the starting point of the buccal scanning of the alveolar ridge of the edentulous maxilla;

[0099] Step 5.2: Hold the scanning head and start from the starting point of the buccal scan of the maxillary edentulous alveolar ridge, and continuously scan along the buccal contour of the alveolar ridge until the end of the position of the right maxillary tuberosity, thus completing the correction of the buccal alveolar ridge. At this time, the intraoral scanner presents a complete intraoral scan model of the maxillary edentulous jaw. This position is used as the end point of the buccal scan of the maxillary edentulous alveolar ridge.

[0100] In step 6, the method of continuously scanning the top of the alveolar ridge of the edentulous mandible by the scanning head along a broken line path around the artificial landmark structure includes the following steps in order:

[0101] Step 6.1: Hold the scanning head and place it on the top of the alveolar ridge on the right side of the edentulous mandible, and use this position as the starting point for scanning the top of the alveolar ridge and the artificial landmark structure on the edentulous mandible. Scan continuously along the mandibular No. 5 artificial landmark structure, mandibular No. 3 artificial landmark structure, mandibular No. 1 artificial landmark structure, mandibular No. 2 artificial landmark structure and mandibular No. 4 artificial landmark structure on the top of the alveolar ridge in a broken line path; when the position of the mandibular No. 5 artificial landmark structure is scanned, tilt the scanning head towards the mandibular No. 5 artificial landmark structure for scanning. At this time, the mandibular No. 5 artificial landmark structure and part of it appear in the scanning model of the intraoral scanner. alveolar ridge; after the scanning of the mandibular No. 5 artificial landmark structure is completed, the scanning head is moved along the zigzag path toward the mandibular No. 3 artificial landmark structure while adjusting the inclination of the scanning head. In the process of moving the scanning head along the zigzag path, the mandibular No. 5 artificial landmark structure, the mandibular No. 5 artificial landmark structure, the mandibular No. 3 artificial landmark structure, and the mandibular No. 3 artificial landmark structure are sequentially presented in the scanning model of the intraoral scanner; when the position of the mandibular No. 3 artificial landmark structure is scanned, the scanning head is tilted toward the mandibular No. 3 artificial landmark structure for scanning, and at this time, the mandibular No. 3 artificial landmark structure and part of the alveolar ridge are presented in the scanning model of the intraoral scanner; and so on;

[0102] Step 6.2: Holding the scanning head, continue to scan continuously around the artificial landmark structure at the top of the alveolar ridge in a zigzag path until the left mandibular molar retromolar pad is finished. At this time, the complete alveolar ridge is presented in the scanning model of the intraoral scanner. This position is used as the end point of the scan of the top of the mandibular edentulous alveolar ridge and the artificial landmark structure on it.

[0103] In step seven, the method of continuously scanning the alveolar ridge lingual side of the edentulous mandible according to the alveolar ridge lingual side contour with the scanning head includes the following steps in order:

[0104] Step 7.1: After the scanning of the top of the alveolar ridge of the edentulous mandible and the artificial landmark structure thereon is completed, the end point of the scanning of the top of the alveolar ridge of the edentulous mandible and the artificial landmark structure thereon is used as the starting point of the lingual scanning of the alveolar ridge of the edentulous mandible;

[0105] Step 7.2: Hold the scanning head and start from the starting point of the lingual scan of the mandibular edentulous alveolar ridge, and continue scanning along the lingual contour of the alveolar ridge until the end of the position of the right mandibular molar back pad. This completes the correction of the lingual alveolar ridge. At this time, 60-70% of the alveolar ridge is presented in the scan model of the intraoral scanner. This position is used as the end point of the lingual scan of the mandibular edentulous alveolar ridge.

[0106] In step eight, the method of continuously scanning the buccal side of the alveolar ridge of the edentulous mandible with the scanning head according to the buccal side contour of the alveolar ridge includes the following steps in order:

[0107] Step 8.1: After the lingual scan of the alveolar ridge of the edentulous mandible is completed, the end point of the lingual scan of the alveolar ridge of the edentulous mandible is used as the starting point of the buccal scan of the alveolar ridge of the edentulous mandible;

[0108] Step 8.2: Hold the scanning head and start from the starting point of the buccal scan of the mandibular edentulous alveolar ridge, and continue scanning along the buccal contour of the alveolar ridge until the position of the left mandibular molar back pad is ended, thus completing the correction of the buccal alveolar ridge. At this time, the intraoral scanner presents a complete intraoral scan model of the mandibular edentulous jaw, and this position is used as the end point of the buccal scan of the mandibular edentulous alveolar ridge.

[0109] In this embodiment, according to Figure 5 The intraoral scanning path shown in the figure is scanned continuously to obtain a complete intraoral scanning model of the maxillary edentulous jaw. The scanned image is as follows: Figure 7 as shown; according to Figure 6 The intraoral scanning path shown in the figure is scanned continuously to obtain a complete intraoral scanning model of the mandibular edentulous jaw. The scanned image is as follows: Figure 8 shown.

[0110] In this implementation, the upper and lower standard edentulous models were selected as the research object, and the scanned models obtained by the model scanner (E4, 3shape, Denmark) were used as the reference. The intraoral scanning models with no artificial landmark structure, three artificial landmark structures, and five artificial landmark structures were obtained by the intraoral scanner (Trios2, 3shape, Denmark) outside the mouth and in the head model. The scanning time and the number of model images were recorded, and the fitting error between the intraoral scanning results and the model scanning results was measured to compare the efficiency and accuracy of the intraoral scanning of the edentulous jaw before and after the artificial landmark structure was set. The setting positions of the five artificial landmark structures are shown in Figure 1. Figure 3 and Figure 4 As shown, the three artificial landmark structures are set at Figure 3 and Figure 4 There are artificial sign structure No. 1, artificial sign structure No. 4 and artificial sign structure No. 5.

[0111] 1. Experiments and data on edentulous maxilla

[0112] The maxillary edentulous model was placed in a model scanner for scanning, and the scanning result was used as the reference model Mlab for accuracy evaluation. A total of 3 models were scanned, and each model was scanned 5 times.

[0113] The maxillary edentulous model was placed on a horizontal plane, and the same operator used a handheld intraoral scanner to scan the model without artificial landmark structures, with three artificial landmark structures, and with five artificial landmark structures according to the intraoral scanning method of this embodiment and the method of FIG. Figure 5The intraoral scanning path shown in the figure is used to scan the extraoral scanning result of the edentulous maxillary. Three models are scanned for each scheme, and each model is scanned 5 times; the scan data are classified into M0, M3 and M5, where M0 is the scan data without setting the artificial landmark structure, M3 is the scan data with three artificial landmark structures, and M5 is the scan data with five artificial landmark structures.

[0114] The head model is fixed on the dental treatment chair, and the maxillary edentulous model is fixed in the head model, with the upper and lower □ planes at 45 degrees to the ground. The same operator uses a handheld intraoral scanner to scan the model without artificial landmark structures, with three artificial landmark structures, and with five artificial landmark structures according to the intraoral scanning method of this embodiment and the method described in the following example. Figure 5 The intraoral scanning path shown in the figure is used to scan and obtain the scanning results of the edentulous maxillary artificial head model. Three models are scanned for each scheme, and each model is scanned 5 times; the scan data are classified into M0', M3' and M5', M0' is the scan data without setting the artificial landmark structure, M3' is the scan data with three artificial landmark structures, and M5' is the scan data with five artificial landmark structures.

[0115] The model scanning data Mlab and the extraoral scanning data M0, M3, and M5 were respectively imported into the reverse engineering software GeomagicWrap 2021 for fitting and analysis. Taking the high-precision scanning result Mlab as the true value standard, the maxillary hard palate part of the model was intercepted, and M0, M3, and M5 were respectively subjected to the best fitting operation with Mlab, and the deviation analysis was performed. The software will automatically obtain the average distance and RMS of the intercepted part, and the RMS of each group will be used as the evaluation value RMSt of the extraoral scanning accuracy error, and recorded. The result with the smallest accuracy error of each model in the three groups of M0, M3, and M5 is used as the reference N0, N3, and N5, and the remaining four scanning results of each model in each group are respectively subjected to the best fitting operation with the corresponding reference, and the deviation analysis is performed. The RMS of each group (a total of 12 in each group) is used as the evaluation value RMSp of the extraoral scanning precision error and recorded. Accuracy and precision together constitute the evaluation of extraoral scanning accuracy.

[0116] The model scanning data Mlab and the in-head model scanning data M0', M3', and M5' were imported into the reverse engineering software Geomagic Wrap 2021 for fitting and analysis. Taking the high-precision scanning result Mlab as the true value standard, the maxillary hard palate part of the model was intercepted, and M0', M3', and M5' were optimally fitted with Mlab, and deviation analysis was performed. The software will automatically obtain the average distance and RMS of the intercepted part, and the RMS of each group will be used as the evaluation value RMSt' of the accuracy error of the in-head model scanning, and recorded. The result with the smallest accuracy error of each model in the three groups of M0', M3', and M5' was used as the reference N0', N3', and N5', and the remaining four scanning results of each model in each group were optimally fitted with the corresponding reference, and deviation analysis was performed. The RMS of each group (12 in total) is used as the evaluation value RMSp' of the precision error of the head-dummy mold scanning, and is recorded. The correctness and precision together constitute the evaluation of the accuracy of the head-dummy mold scanning.

[0117] SPSS26.0 statistical software was used to process the test results as follows: the group without artificial landmark structure, the group with three artificial landmark structures, and the group with five artificial landmark structures were divided into different groups. After the variance homogeneity test and normality test, the data of each group were subjected to one-way analysis of variance to test the inter-group differences in scanning time T, number of images Pol, scanning correctness RMSt, scanning precision RMSp of the three groups of extraoral test and scanning time T', number of images Pol', scanning correctness RMSt', scanning precision RMSp' of the three groups of in-head model test, respectively. The test standard α = 0.05. The test data of the edentulous maxillary extraoral test are shown in Table 1, and the test data of the edentulous maxillary in-head model are shown in Table 2; the analysis of the scanning results of the edentulous maxillary extraoral and in-head model are shown in Table 2. Fig. 9 As shown, among them: (a) is the scanning time analysis diagram, (b) is the image quantity analysis diagram, (c) is the scanning correctness analysis diagram, and (d) is the scanning precision analysis diagram.

[0118] Table 1 Extraoral test data of the edentulous maxilla (mean ± SD)

[0119] Analyze Project M0 M3 M5 T(s) 79.8±14.1 70.6±13.1 56.5±6.7*** Pol(pcs) 1432.0±209.5 1282±134.4** 1049.0±100.7*** RMSt(μm) 125.4±28.7 123.4±32.1 104.2±24.0 RMSp(μm) 72.6±17.7 69.8±36.3 54.0±20.8

[0120] Note: *P<0.05, **P<0.01, ***P<0.001.

[0121] Table 2 Experimental data in the edentulous maxillary head model (mean ± standard deviation)

[0122] Analyze Project M0＇ M3＇ M5＇ T'(s) 92.5±7.3 84.5±11.9 68.9±7.2*** Pol'(pcs) 1604.0±143.0 1383.0±67.6** 1155.0±75.9*** RMSt'(μm) 124.0±29.0 104.2±16.4* 100.2±18.5* RMSp'(μm) 79.9±19.2 75.3±24.9 56.8±16.1*

[0123] Note: *P<0.05, **P<0.01, ***P<0.001.

[0124] From Table 1 and Fig. 9 It can be seen that under the condition of extraoral scanning, compared with the scanning scheme without artificial landmark structures, the scanning scheme with three artificial landmark structures significantly reduced the number of polygons in the scanning results (P<0.01), but there was no significant difference in the scanning time, scanning accuracy and scanning precision (P>0.05); the scanning scheme with five artificial landmark structures significantly reduced the scanning time and the number of polygons in the scanning results (P<0.001), but there was no significant difference in scanning accuracy and scanning precision (P>0.05). The experimental results show that setting artificial landmark structures can significantly improve the scanning efficiency of edentulous maxillary extraoral, and as the number of artificial landmark structures increases, the improvement effect brought by setting artificial landmark structures is more obvious.

[0125] From Table 2 and Fig. 9 It can be seen that under the condition of clinical scanning in the head model, compared with the scanning scheme without artificial landmark structures, the scanning scheme with three artificial landmark structures significantly reduced the number of polygons in the scanning results (P<0.01), significantly improved the scanning accuracy (P<0.05), and had no significant difference in the scanning time and scanning precision (P>0.05); the scanning scheme with five artificial landmark structures significantly reduced the scanning time and the number of polygons in the scanning results (P<0.001), significantly improved the scanning accuracy (P<0.05), and had no significant difference in scanning precision (P>0.05). The experimental results show that setting artificial landmark structures can significantly improve the scanning efficiency in the edentulous maxillary head model, and improve the scanning accuracy by improving the scanning accuracy. With the increase in the number of artificial landmark structures, the improvement effect brought by setting artificial landmark structures is more obvious.

[0126] 2. Experiments and data on edentulous mandible

[0127] The mandibular edentulous model was placed in a model scanner for scanning, and the scanning result was used as the reference model Mlab for accuracy evaluation. A total of 3 models were scanned, and each model was scanned 5 times.

[0128] The mandibular edentulous model was placed on a horizontal plane, and the same operator held an intraoral scanner to scan the model without artificial landmark structures, with three artificial landmark structures, and with five artificial landmark structures according to the intraoral scanning method of this embodiment and the method of FIG. Figure 6 The intraoral scanning path shown in the figure is used to scan the extraoral scanning result of the edentulous maxillary. Three models are scanned for each scheme, and each model is scanned 5 times; the scan data are classified into M0, M3 and M5, where M0 is the scan data without setting the artificial landmark structure, M3 is the scan data with three artificial landmark structures, and M5 is the scan data with five artificial landmark structures.

[0129] The head model is fixed on the dental treatment chair, and the upper and lower edentulous models are fixed in the head model, with the upper and lower □ planes at 45 degrees to the ground. The same operator holds an intraoral scanner to scan the model without artificial landmark structures, with three artificial landmark structures, and with five artificial landmark structures according to the intraoral scanning method of this embodiment and the method of FIG. Figure 6 The intraoral scanning path shown in the figure is used to scan and obtain the scanning results of the mandibular edentulous mandible simulation head model. Three models are scanned for each scheme, and each model is scanned 5 times; the scan data are classified into M0', M3' and M5', M0' is the scan data without setting the artificial landmark structure, M3' is the scan data with three artificial landmark structures, and M5' is the scan data with five artificial landmark structures.

[0130] The model scanning data Mlab and the extraoral scanning data M0, M3, and M5 were respectively imported into the reverse engineering software GeomagicWrap 2021 for fitting and analysis. Taking the high-precision scanning result Mlab as the true value standard, the mandibular alveolar ridge part of the model was intercepted, and M0, M3, and M5 were respectively subjected to the best fitting operation with Mlab, and the deviation analysis was performed. The software will automatically obtain the average distance and RMS of the intercepted part, and the RMS of each group will be used as the evaluation value RMSt of the extraoral scanning accuracy error, and recorded. The result with the smallest accuracy error of each model in the three groups of M0, M3, and M5 is used as the reference N0, N3, and N5, and the remaining four scanning results of each model in each group are respectively subjected to the best fitting operation with the corresponding reference, and the deviation analysis is performed. The RMS of each group (a total of 12 in each group) is used as the evaluation value RMSp of the extraoral scanning precision error and recorded. Accuracy and precision together constitute the evaluation of extraoral scanning accuracy.

[0131] The model scanning data Mlab and the in-head model scanning data M0', M3', and M5' were imported into the reverse engineering software Geomagic Wrap 2021 for fitting and analysis. Taking the high-precision scanning result Mlab as the true value standard, the mandibular alveolar ridge part of the model was intercepted, and M0', M3', and M5' were optimally fitted with Mlab, and deviation analysis was performed. The software will automatically obtain the average distance and RMS of the intercepted part, and the RMS of each group will be used as the evaluation value RMSt' of the accuracy error of the in-head model scanning, and recorded. The result with the smallest accuracy error of each model in the three groups of M0', M3', and M5' was used as the reference N0', N3', and N5', and the remaining four scanning results of each model in each group were optimally fitted with the corresponding reference, and deviation analysis was performed. The RMS of each group (12 in total) is used as the evaluation value RMSp' of the precision error of the head-dummy mold scanning, and is recorded. The correctness and precision together constitute the evaluation of the accuracy of the head-dummy mold scanning.

[0132] SPSS26.0 statistical software was used to process the test results as follows: the group without artificial landmark structure, the group with three artificial landmark structures, and the group with five artificial landmark structures were divided into different groups. After the variance homogeneity test and normality test, the data of each group were subjected to one-way analysis of variance to test the inter-group differences in scanning time T, number of images Pol, scanning correctness RMSt, scanning precision RMSp of the three groups of extraoral test and scanning time T', number of images Pol', scanning correctness RMSt', scanning precision RMSp' of the three groups of in-head model test, respectively. The test standard α = 0.05. The test data of the edentulous mandible outside the mouth are shown in Table 3, and the test data of the edentulous mandible inside the head model are shown in Table 4; the analysis of the scanning results of the edentulous mandible outside the mouth and inside the head model is shown in Table 4. Fig.10 As shown, among them: (a) is the scanning time analysis diagram, (b) is the image quantity analysis diagram, (c) is the scanning correctness analysis diagram, and (d) is the scanning precision analysis diagram.

[0133] Table 3 Extraoral test data of edentulous mandible (mean ± SD)

[0134]

[0135]

[0136] Note: *P<0.05, **P<0.01, ***P<0.001.

[0137] Table 4 Test data in the mandibular edentulous head model (mean ± standard deviation)

[0138] Analyze Project M0＇ M3＇ M5＇ T'(s) 95.1±20.4 82.6±8.4 74.0±9.7*** Pol'(pcs) 1642.3±187.3 1499.3±131.2 1268.8±118.0*** RMSt'(μm) 82.3±19.0 89.5±19.9 82.4±19.5 RMSp'(μm) 92.0±18.8 100.4±29.1 97.0±17.1

[0139] Note: *P<0.05, **P<0.01, ***P<0.001.

[0140] From Table 3 and Fig.10 It can be seen that under the condition of extraoral scanning, compared with the scanning scheme without artificial landmark structures, the scanning scheme with three artificial landmark structures significantly reduced the scanning time and the number of scanning result polygons (P<0.001), but there was no significant difference in scanning correctness and scanning precision (P>0.05); the scanning scheme with five artificial landmark structures significantly reduced the scanning time and the number of scanning result polygons (P<0.001), and significantly improved the scanning precision (P<0.01), but there was no significant difference in scanning correctness. The experimental results show that setting artificial landmark structures can significantly improve the scanning efficiency of edentulous mandibles outside the mouth, and as the number of artificial landmark structures increases, the improvement effect brought by setting artificial landmark structures is more obvious.

[0141] From Table 4 and Fig.10 It can be seen that under the condition of clinical scanning in the head model, compared with the scanning plan without artificial landmark structures, the scanning plan with three artificial landmark structures had no significant difference in the scanning time, the number of scanning result polygons, the scanning correctness and the scanning precision (P>0.05); the scanning plan with five artificial landmark structures significantly reduced the scanning time and the number of scanning result polygons (P<0.001), but had no significant difference in scanning correctness and scanning precision (P>0.05). The experimental results show that setting artificial landmark structures cannot improve the scanning accuracy of edentulous mandibles, but can significantly improve the scanning efficiency in the head model of edentulous mandibles. As the number of artificial landmark structures increases, the improvement effect brought by setting artificial landmark structures is more obvious.

[0142] This embodiment shows through in vitro tests that setting a raised artificial landmark structure on the alveolar ridge of the edentulous jaw can effectively improve the scanning efficiency, and can improve the accuracy of scanning the hard palate by improving the accuracy. Compared with the scheme without setting an artificial landmark structure, the scheme with three artificial landmark structures and the scheme with five artificial landmark structures have observable improvements in scanning efficiency and scanning accuracy, especially the improvement effect of setting five artificial landmark structures is more obvious, which shows that the improvement of the scanning effect by the artificial landmark structure is related to the number of artificial landmark structures set within a certain range. The main reason is that when one or more artificial landmark structures appear in the field of view of the intraoral scanner at the same time, it can play a good positioning role, and the efficiency and accuracy of the intraoral scanner in judging the relative position of the artificial landmark structure in the current field of view and the artificial landmark structure that has been scanned previously are greatly improved. Compared with the scanning condition of placing the edentulous jaw model outside the mouth, setting up an artificial landmark structure in the scanning condition of simulating the clinical environment in the head model has a more significant improvement on the scanning effect. This shows that the setting of the artificial landmark structure has improved the efficiency decline caused by the limited movement of the scanning head under clinical conditions to a certain extent, such as slow recognition and easy errors in splicing. It also relatively improves the interference of other structures and reflections in the mouth on the scanning accuracy, such as the surface features of soft tissue are not recognized or recognized as nail-like objects, and other structures are incorrectly spliced ​​into the image of the maxillary hard palate area.

[0143] Embodiment 2:

[0144] According to another preferred embodiment of the artificial landmark structure for intraoral scanning of edentulous jaw and the intraoral scanning method thereof of the present invention, the artificial landmark structure and material, intraoral scanning method and scanning device, analysis method, technical principle, beneficial effects, etc. are basically the same as those of the first embodiment, except that:

[0145] The diameter of the patch layer is 5mm and the thickness is 0.4mm; the diameter of the adhesive layer is equal to the diameter of the patch layer, and the thickness of the adhesive layer is 0.1mm; the bottom diameter of the sign body is equal to the diameter of the adhesive layer, the top diameter of the sign body is 0.5 times the bottom diameter, and the height of the sign body is 0.4 times the bottom diameter.

[0146] The patch layer is composed of hyaluronic acid, corn starch and polyethylene glycol, wherein the mass percentage of each substance in the patch layer is 80wt% hyaluronic acid, 10wt% corn starch and 10wt% polyethylene glycol; the material of the adhesive layer is liquid carrageenan; and the material of the marker is resin.

[0147] Embodiment three:

[0148] According to another preferred embodiment of the artificial landmark structure for intraoral scanning of edentulous jaw and the intraoral scanning method thereof of the present invention, the artificial landmark structure and material, intraoral scanning method and scanning device, analysis method, technical principle, beneficial effects, etc. are basically the same as those of the first embodiment, except that:

[0149] The diameter of the patch layer is 3mm and the thickness is 0.2mm; the diameter of the adhesive layer is equal to the diameter of the patch layer, and the thickness of the adhesive layer is 0.05mm; the bottom diameter of the sign body is equal to the diameter of the adhesive layer, the top diameter of the sign body is 0.5 times the bottom diameter, and the height of the sign body is 0.4 times the bottom diameter.

[0150] The patch layer is composed of hyaluronic acid, corn starch and polyethylene glycol, wherein the mass percentage of each substance in the patch layer is 70wt% hyaluronic acid, 20wt% corn starch and 10wt% polyethylene glycol; the material of the adhesive layer is liquid carrageenan; and the material of the marker is resin.

[0151] Special note: The technical solution of the present invention involves many parameters, and the synergistic effects between the various parameters need to be comprehensively considered to obtain the beneficial effects and significant progress of the present invention. Moreover, the value ranges of the various parameters in the technical solution are obtained after a large number of experiments. For each parameter and the combination of each parameter, the inventor has recorded a large amount of experimental data. Due to space limitations, the specific experimental data will not be disclosed here.

[0152] It is not difficult for a person skilled in the art to understand that the artificial landmark structure for intraoral scanning of edentulous jaws and the intraoral scanning method thereof of the present invention include any combination of the invention content and specific implementation methods of the above-mentioned invention specification and the various parts shown in the drawings, and due to the limited space and to make the specification concise, the various schemes composed of these combinations are not described one by one. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An artificial landmark structure for intraoral scanning of edentulous jaws, characterized by: It comprises a patch layer, an adhesive layer and a sign body which are arranged in sequence from bottom to top, the patch layer and the adhesive layer are both circular, the sign body is a truncated cone, and the side surface of the sign body is composed of six identical arc surfaces; The patch layer has a diameter of 3-5 mm and a thickness of 0.2-0.4 mm; the adhesive layer has a diameter equal to that of the patch layer, and a thickness of 0.05-0.1 mm; the bottom diameter of the logo body is equal to that of the adhesive layer, the top diameter of the logo body is 0.5 times the bottom diameter, and the height of the logo body is 0.4 times the bottom diameter; the overall shape of the logo body is a diamond-like structure, and its outer surface is matte-finished; The patch layer is composed of hyaluronic acid, corn starch and polyethylene glycol, wherein the mass percentage of each substance in the patch layer is 70-80wt% of hyaluronic acid, 10-20wt% of corn starch, and 5-10wt% of polyethylene glycol; the material of the adhesive layer is liquid carrageenan; and the material of the marker is resin.

2. An intraoral scanning method for edentulous jaws, characterized in that: Using the artificial landmark structure for intraoral scanning of edentulous jaws according to claim 1, the following steps are included in order: Step 1: According to the design requirements, artificial landmark structures are set on the top of the alveolar ridge of the maxillary edentulous jaw and the top of the alveolar ridge of the mandibular edentulous jaw respectively; Step 2: Start the intraoral scanner, hold the scanning head, and make the scanning head scan continuously in the palate area of ​​the maxillary edentulous jaw in an S-shaped path; Step 3: After the scanning of the palatal area of ​​the edentulous maxilla is completed, the scanning path of the scanning head is adjusted so that the scanning head continuously scans the palatal side of the alveolar ridge of the edentulous maxilla according to the palatal side contour of the alveolar ridge; Step 4: After the palatal scanning of the alveolar ridge of the edentulous maxilla is completed, the scanning path of the scanning head is adjusted so that the scanning head continuously scans around the artificial landmark structure along a broken line path at the top of the alveolar ridge of the edentulous maxilla; Step 5: After the scanning of the alveolar ridge top of the edentulous maxilla and the artificial landmark structure thereon is completed, the scanning path of the scanning head is adjusted so that the scanning head continuously scans the buccal side of the alveolar ridge of the edentulous maxilla according to the buccal contour of the alveolar ridge; after the buccal side of the alveolar ridge of the edentulous maxilla is scanned, a complete intraoral scanning model of the edentulous maxilla can be obtained; Step 6: Place the scanning head on the top of the alveolar ridge of the edentulous mandible, and adjust the scanning path of the scanning head so that the scanning head continuously scans around the artificial landmark structure along a zigzag path on the top of the alveolar ridge of the edentulous mandible; Step 7: After the top of the alveolar ridge of the edentulous mandible and the artificial landmark structure thereon are scanned, the scanning path of the scanning head is adjusted so that the scanning head continuously scans the lingual side of the alveolar ridge of the edentulous mandible according to the lingual side contour of the alveolar ridge; Step 8: After the lingual scan of the alveolar ridge of the edentulous mandible is completed, adjust the scanning path of the scanning head so that the scanning head continuously scans the buccal side of the alveolar ridge of the edentulous mandible according to the buccal contour of the alveolar ridge; after the buccal scan of the alveolar ridge of the edentulous mandible is completed, a complete intraoral scan model of the edentulous mandible can be obtained.

3. The intraoral scanning method for edentulous jaws according to claim 2, characterized in that: In step one, five artificial landmark structures are set on the top of the alveolar ridge of the maxillary edentulous jaw, wherein the maxillary No. 1 artificial landmark structure is located at the middle top of the alveolar ridge of the upper anterior teeth; the maxillary No. 2 artificial landmark structure is located at the position of the first premolar on the left side of the original maxillary dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position; the maxillary No. 3 artificial landmark structure is located at the position of the first premolar on the right side of the original maxillary dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position; the maxillary No. 4 artificial landmark structure is located at the position of the second molar on the left side of the original maxillary dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position, and is located in front of the left maxillary tubercle; the maxillary No. 5 artificial landmark structure is located at the position of the second molar on the right side of the original maxillary dentition corresponding to the alveolar ridge, and the area 2-3mm forward or backward along the top of the alveolar ridge at this position, and is located in front of the right maxillary tubercle; Five artificial landmark structures are set on the top of the alveolar ridge of the edentulous mandible, among which the mandibular artificial landmark structure No. 1 is located at the central top of the alveolar ridge of the lower front teeth; the mandibular artificial landmark structure No. 2 is located at the position of the first premolar on the left side of the original mandibular dentition corresponding to the alveolar ridge, and in the area 2-3mm forward or backward along the top of the alveolar ridge at this position; the mandibular artificial landmark structure No. 3 is located at the position of the first premolar on the right side of the original mandibular dentition corresponding to the alveolar ridge, and in the area 2-3mm forward or backward along the top of the alveolar ridge at this position; the mandibular artificial landmark structure No. 4 is located at the position of the second molar on the left side of the original mandibular dentition corresponding to the alveolar ridge, and in the area 2-3mm forward or backward along the top of the alveolar ridge at this position, and in front of the left mandibular molar back pad; the mandibular artificial landmark structure No. 5 is located at the position of the second molar on the right side of the original mandibular dentition corresponding to the alveolar ridge, and in the area 2-3mm forward or backward along the top of the alveolar ridge at this position, and in front of the right mandibular molar back pad.

4. The intraoral scanning method for edentulous jaws according to claim 3, characterized in that: In step 2, the method of continuously scanning the palate region of the maxillary edentulous jaw with the scanning head in an S-shaped path includes the following steps in order: Step 2.1: Hold the scanning head and place it at the front of the maxillary edentulous palate near the maxillary No. 1 artificial landmark structure. At this time, the maxillary No. 1 artificial landmark structure appears in the field of view of the intraoral scanner. This position is used as the starting point for scanning the maxillary edentulous palate area. Step 2.2: Hold the scanning head and start from the starting point of the maxillary edentulous palate scanning, first move the scanning head to the left side of the palate, and then scan continuously from the front to the back of the palate along an S-shaped path; in the process of scanning in the first complete transverse scanning area, the maxillary No. 2 artificial landmark structure and the maxillary No. 3 artificial landmark structure are simultaneously presented in the scanning model of the intraoral scanner; in the process of scanning in the third to fourth complete transverse scanning areas, the maxillary No. 4 artificial landmark structure and the maxillary No. 5 artificial landmark structure are simultaneously presented in the scanning model of the intraoral scanner; Step 2.3: Holding the scanning head, continue scanning toward the posterior part of the palate along the S-shaped path until the right maxillary tuberosity is reached. At this time, at least 50% of the alveolar ridge is present in the scanning model of the intraoral scanner. This position is taken as the end point of the maxillary edentulous palate scan.

5. The intraoral scanning method for edentulous jaws according to claim 4, characterized in that: In step 3, the scanning head continuously scans the palatal side of the alveolar ridge of the edentulous maxilla according to the palatal side contour of the alveolar ridge, and the method includes the following steps in order: Step 3.1: After the palatal scan of the edentulous maxilla is completed, the end point of the palatal scan of the edentulous maxilla is used as the starting point of the palatal scan of the edentulous maxilla alveolar ridge; Step 3.2: Hold the scanning head and start from the starting point of the palatal scan of the maxillary edentulous alveolar ridge, and scan continuously along the palatal contour of the alveolar ridge until the end of the left maxillary tuberosity. This completes the correction of the palatal alveolar ridge. At this time, 60-70% of the alveolar ridge is presented in the scanning model of the intraoral scanner. This position is used as the end point of the palatal scan of the maxillary edentulous alveolar ridge.

6. The intraoral scanning method for edentulous jaws according to claim 5, characterized in that: In step 4, the method of continuously scanning the top of the alveolar ridge of the edentulous maxilla by the scanning head along a broken line path around the artificial landmark structure includes the following steps in order: Step 4.1: After the palatal scan of the maxillary edentulous alveolar ridge is completed, the end point of the palatal scan of the maxillary edentulous alveolar ridge is used as the starting point of the scan of the maxillary edentulous alveolar ridge top and the artificial landmark structure thereon; Step 4.2: Hold the scanning head and start from the top of the maxillary edentulous alveolar ridge and the starting point of the scanning of the artificial landmark structure on it, and scan continuously around the maxillary No. 4 artificial landmark structure, the maxillary No. 2 artificial landmark structure, the maxillary No. 1 artificial landmark structure, the maxillary No. 3 artificial landmark structure and the maxillary No. 5 artificial landmark structure in a broken line path at the top of the alveolar ridge; when the maxillary No. 4 artificial landmark structure is scanned, tilt the scanning head toward the maxillary No. 4 artificial landmark structure for scanning. At this time, the maxillary No. 4 artificial landmark structure and part of the alveolar ridge will appear in the scanning model of the intraoral scanner; wait for the maxillary No. 4 artificial landmark structure to be scanned. After the scanning of the maxillary landmark structure is completed, the scanning head is moved along the zigzag path toward the maxillary No. 2 artificial landmark structure while adjusting its inclination. In the process of moving the scanning head along the zigzag path, the maxillary No. 4 artificial landmark structure, the maxillary No. 4 artificial landmark structure, the maxillary No. 2 artificial landmark structure, and the maxillary No. 2 artificial landmark structure are sequentially presented in the scanning model of the intraoral scanner; when the maxillary No. 2 artificial landmark structure is scanned, the scanning head is tilted toward the maxillary No. 2 artificial landmark structure for scanning, and at this time, the maxillary No. 2 artificial landmark structure and part of the alveolar ridge are presented in the scanning model of the intraoral scanner; and so on; Step 4.3: Holding the scanning head, continue scanning along the zigzag path around the artificial landmark structure at the top of the alveolar ridge until the left maxillary tuberosity is reached. At this time, the complete alveolar ridge is presented in the scanning model of the intraoral scanner. This position is used as the end point of the scan of the top of the maxillary edentulous alveolar ridge and the artificial landmark structure on it.

7. The intraoral scanning method for edentulous jaws according to claim 6, characterized in that: In step 5, the method of continuously scanning the buccal side of the alveolar ridge of the edentulous maxilla with the scanning head according to the buccal side contour of the alveolar ridge includes the following steps in order: Step 5.1: After the scanning of the top of the alveolar ridge of the edentulous maxilla and the artificial landmark structure thereon is completed, the end point of the scanning of the top of the alveolar ridge of the edentulous maxilla and the artificial landmark structure thereon is used as the starting point of the buccal scanning of the alveolar ridge of the edentulous maxilla; Step 5.2: Hold the scanning head and start from the starting point of the buccal scan of the maxillary edentulous alveolar ridge, and continuously scan along the buccal contour of the alveolar ridge until the end of the position of the right maxillary tuberosity, thus completing the correction of the buccal alveolar ridge. At this time, the intraoral scanner presents a complete intraoral scan model of the maxillary edentulous jaw. This position is used as the end point of the buccal scan of the maxillary edentulous alveolar ridge.

8. The intraoral scanning method of edentulous jaw according to claim 7, characterized in that: In step 6, the method of continuously scanning the top of the alveolar ridge of the edentulous mandible by the scanning head along a broken line path around the artificial landmark structure includes the following steps in order: Step 6.1: Hold the scanning head and place it on the top of the alveolar ridge on the right side of the edentulous mandible, and use this position as the starting point for scanning the top of the alveolar ridge and the artificial landmark structure on the edentulous mandible. Scan continuously along the mandibular No. 5 artificial landmark structure, mandibular No. 3 artificial landmark structure, mandibular No. 1 artificial landmark structure, mandibular No. 2 artificial landmark structure and mandibular No. 4 artificial landmark structure on the top of the alveolar ridge in a broken line path; when the position of the mandibular No. 5 artificial landmark structure is scanned, tilt the scanning head towards the mandibular No. 5 artificial landmark structure for scanning. At this time, the mandibular No. 5 artificial landmark structure and part of it appear in the scanning model of the intraoral scanner. alveolar ridge; after the scanning of the mandibular No. 5 artificial landmark structure is completed, the scanning head is moved along the zigzag path toward the mandibular No. 3 artificial landmark structure while adjusting the inclination of the scanning head. In the process of moving the scanning head along the zigzag path, the mandibular No. 5 artificial landmark structure, the mandibular No. 5 artificial landmark structure, the mandibular No. 3 artificial landmark structure, and the mandibular No. 3 artificial landmark structure are sequentially presented in the scanning model of the intraoral scanner; when the position of the mandibular No. 3 artificial landmark structure is scanned, the scanning head is tilted toward the mandibular No. 3 artificial landmark structure for scanning, and at this time, the mandibular No. 3 artificial landmark structure and part of the alveolar ridge are presented in the scanning model of the intraoral scanner; and so on; Step 6.2: Holding the scanning head, continue to scan continuously around the artificial landmark structure at the top of the alveolar ridge in a zigzag path until the left mandibular molar retromolar pad is finished. At this time, the complete alveolar ridge is presented in the scanning model of the intraoral scanner. This position is used as the end point of the scan of the top of the mandibular edentulous alveolar ridge and the artificial landmark structure on it.

9. The intraoral scanning method of edentulous jaw according to claim 8, characterized in that: In step seven, the method of continuously scanning the alveolar ridge lingual side of the edentulous mandible according to the alveolar ridge lingual side contour with the scanning head includes the following steps in order: Step 7.1: After the scanning of the top of the alveolar ridge of the edentulous mandible and the artificial landmark structure thereon is completed, the end point of the scanning of the top of the alveolar ridge of the edentulous mandible and the artificial landmark structure thereon is used as the starting point of the lingual scanning of the alveolar ridge of the edentulous mandible; Step 7.2: Hold the scanning head and start from the starting point of the lingual scan of the mandibular edentulous alveolar ridge, and continue scanning along the lingual contour of the alveolar ridge until the end of the position of the right mandibular molar back pad. This completes the correction of the lingual alveolar ridge. At this time, 60-70% of the alveolar ridge is presented in the scan model of the intraoral scanner. This position is used as the end point of the lingual scan of the mandibular edentulous alveolar ridge.

10. The intraoral scanning method of edentulous jaw according to claim 9, characterized in that: In step eight, the method of continuously scanning the buccal side of the alveolar ridge of the edentulous mandible by the scanning head according to the buccal side contour of the alveolar ridge includes the following steps in order: Step 8.1: After the lingual scan of the alveolar ridge of the edentulous mandible is completed, the end point of the lingual scan of the alveolar ridge of the edentulous mandible is used as the starting point of the buccal scan of the alveolar ridge of the edentulous mandible; Step 8.2: Hold the scanning head and start from the starting point of the buccal scan of the mandibular edentulous alveolar ridge, and continue scanning along the buccal contour of the alveolar ridge until the position of the left mandibular molar back pad is ended, thus completing the correction of the buccal alveolar ridge. At this time, the intraoral scanner presents a complete intraoral scan model of the mandibular edentulous jaw, and this position is used as the end point of the buccal scan of the mandibular edentulous alveolar ridge.

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