Standardized three-dimensional periodontal attachment quantification system and method

Abstract

The invention discloses a standardized three-dimensional periodontal attachment quantification system and method, and relates to the technical field of digital oral medicine, and the method comprises the following steps: calibrating a cementum-enamel boundary, dividing a tooth model into a dental crown and a tooth root, and determining the total surface area of the tooth root; performing sensitivity analysis by using the candidate threshold sequence, and determining an optimal diagnosis threshold in combination with a surface integrity criterion; based on the optimal diagnostic threshold, an absolute adhesion area and a relative adhesion area ratio are calculated and output. The invention provides a quantitative method capable of truly, comprehensively and accurately reflecting the three-dimensional pathological change of the periodontal tissue, and the accuracy of a measurement result is ensured through standardized crown root segmentation and accurate geometric judgment; through data-driven parameter optimization, uncertainty caused by manual intervention is eradicated, and objectivity and repeatability of a measurement result are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of digital stomatology, and more particularly to a standardized three-dimensional periodontal attachment quantification system and method. Background Art

[0002] Periodontitis, which causes irreversible destruction of periodontal support tissues, is the leading cause of tooth loss in adults. Accurately quantifying the extent of periodontal attachment loss is crucial for disease diagnosis, severity grading, treatment selection, and efficacy evaluation. However, currently used measurement methods have well-known limitations and cannot truly reflect the complex three-dimensional pathological changes surrounding teeth, as follows:

[0003] (1) Two-dimensional X-ray technology

[0004] Missing and distorted information dimensions: Unable to display buccal and lingual bone resorption; overlapping images of adjacent teeth and anatomical structures; different projection angles will produce geometric magnification or reduction, making accurate measurement impossible.

[0005] Non-quantitative in nature: only semi-quantitative "estimates" can be made based on the doctor's experience, such as "alveolar bone absorption reaches 1 / 3 of the root length", which is highly subjective and cannot provide accurate attachment area data.

[0006] (2) Clinical exploration techniques (PD, CAL)

[0007] What is measured is one-dimensional "depth" rather than three-dimensional "area", which cannot reflect the breadth of attachment loss; the results are affected by many factors such as probe brand, penetration force, gingival inflammation status, patient cooperation, etc., and the repeatability is poor.

[0008] (3) Scattered, non-standardized three-dimensional attempts

[0009] Previous sporadic scientific research attempts either simply performed linear measurements on three-dimensional models, or adopted overly simplified geometric judgments and arbitrary parameter selections, failing to form a recognized, complete, and standardized methodological system. The results often had poor reproducibility and could not be promoted in clinical practice.

[0010] Therefore, how to create and define a complete, standardized three-dimensional periodontal attachment quantification technology system to completely replace the traditional imprecise and non-quantitative evaluation methods is a technical problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0011] In light of this, the present invention provides a standardized three-dimensional periodontal attachment quantification system and method. Its fundamental purpose is to establish and define a complete, standardized three-dimensional periodontal attachment quantification technology system to completely replace traditional imprecise and non-quantitative assessment methods. This system aims to achieve: a. a leap from two-dimensional to three-dimensional: providing a quantification method that can truly, comprehensively, and accurately reflect three-dimensional pathological changes in periodontal tissues; b. a leap from fuzzy to precise: ensuring the accuracy of measurement results through standardized crown-root segmentation and precise geometric determination; c. a leap from subjective to objective: eliminating the uncertainty caused by human intervention through data-driven parameter optimization, ensuring the objectivity and repeatability of measurement results.

[0012] In order to achieve the above object, the present invention provides the following technical solutions:

[0013] A standardized three-dimensional periodontal attachment quantification method includes the following steps:

[0014] The cementum-enamel boundary was demarcated, the tooth model was divided into the crown and root, and the total root surface area was determined;

[0015] Sensitivity analysis was performed using a sequence of candidate thresholds, and the optimal diagnostic threshold was determined in combination with the facet completeness criterion;

[0016] Based on the optimal diagnostic threshold, the absolute attachment area and relative attachment area ratio are calculated and output.

[0017] Optionally, the cementum-enamel boundary is demarcated, specifically comprising the following steps:

[0018] Using segmentation technology, a 3D surface model of the target tooth and its surrounding alveolar bone is extracted from the patient's CBCT data;

[0019] For the target tooth model, multiple predefined sparse anatomical landmarks are marked along the contour of the cementum-enamel junction;

[0020] The cubic B-spline interpolation algorithm is applied to multiple sparse anatomical landmarks to automatically fit a continuous, smooth and closed three-dimensional spatial curve;

[0021] Through the nearest neighbor algorithm, the three-dimensional space curve is projected or adsorbed onto the real surface of the target tooth model to obtain a final CEJ curve that is completely composed of tooth surface vertices and fits the anatomical morphology.

[0022] Optionally, the tooth model is segmented into crowns and roots, specifically comprising the following steps:

[0023] Using the final CEJ curve as the cutting boundary, the original complete tooth model is split into two independent parts without overlap: the crown model and the root model;

[0024] Calculate the total surface area of ​​the tooth root model and record it as A_total_root.

[0025] Optionally, a sensitivity analysis is performed using a candidate threshold sequence, specifically including the following steps:

[0026] For any triangular facet on the tooth root model, calculate the closest distances between the three vertices and the surface of the alveolar bone model;

[0027] If the closest distances between the three vertices are all less than or equal to a given distance threshold, the triangle is counted into the attachment area;

[0028] Through a loop, an attachment area calculation is performed for each candidate threshold in the candidate threshold sequence.

[0029] Optionally, determining the optimal diagnostic threshold may include the following steps:

[0030] Based on a series of "threshold-area" data pairs obtained after sensitivity analysis, draw the "area-threshold" sensitivity curve;

[0031] The geometric shape of the "area-threshold" sensitivity curve is automatically analyzed mathematically, and the point with the maximum curvature on the curve is calculated and found as the inflection point. The horizontal coordinate value corresponding to the inflection point is determined as the optimal diagnostic threshold T_optimal.

[0032] A standardized three-dimensional periodontal attachment quantification system, which executes any one of the above-mentioned standardized three-dimensional periodontal attachment quantification methods, comprising:

[0033] The root analysis region definition module is used to calibrate the cementum-enamel boundary, segment the tooth model into the crown and root, and determine the total root surface area;

[0034] An attachment geometry determination module is used to perform sensitivity analysis using a candidate threshold sequence and determine the optimal diagnostic threshold in combination with a surface integrity criterion;

[0035] The result integration and output module is used to calculate and output the absolute attachment area and the relative attachment area ratio according to the optimal diagnostic threshold.

[0036] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a standardized three-dimensional periodontal attachment quantification system and method, which has the following beneficial effects:

[0037] (1) Create a new diagnostic paradigm: Promoting periodontal disease diagnosis from the traditional "estimation era" based on two-dimensional imaging and one-dimensional probing to the "precision quantification era" based on three-dimensional measured data, which is a revolutionary upgrade to the existing clinical diagnostic model;

[0038] (2) Significantly improve diagnostic accuracy and reliability: Providing objective and accurate three-dimensional attachment area data can more realistically reflect the condition and avoid misdiagnosis or missed diagnosis caused by the subjectivity and uncertainty of traditional methods;

[0039] (3) Achieve standardization of efficacy evaluation: It provides a unified and reliable quantitative gold standard for the evaluation of the effects of advanced therapies such as periodontal regeneration therapy, and can accurately calculate the "real" regenerated attachment area after treatment, which is of great scientific and clinical value;

[0040] (4) Empowering personalized precision medicine: Based on accurate quantitative results, doctors can develop more personalized treatment plans for patients, more scientifically judge the prognosis of teeth and the timing of tooth extraction, and comprehensively improve the diagnosis and treatment of periodontal disease. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0042] Figure 1 A flow chart of the standardized three-dimensional periodontal attachment quantification method provided by the present invention;

[0043] Figure 2 A complete technical flow chart provided for the present invention;

[0044] Figure 3 A schematic diagram of the interface for teeth and alveolar bone segmentation and CEJ feature point annotation in the three-dimensional interactive software provided by the present invention;

[0045] Figure 4 A schematic diagram of the process of the background automation program provided by the present invention reading characteristic points and generating accurate CEJ curves;

[0046] Figure 5 This is a schematic diagram of the result of accurately segmenting a tooth model into a crown and a root based on the CEJ curve provided by the present invention;

[0047] Figure 6 A schematic diagram of the principle of the surface integrity attachment judgment criterion provided by the present invention;

[0048] Figure 7 Schematic diagram of the present invention for data-driven determination of the optimal diagnostic threshold using the “area-threshold” sensitivity curve. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] For decades, clinical practice has relied on two-dimensional radiographs to estimate bone resorption and manual periodontal probing to measure probing depth (PD) and clinical attachment loss (CAL). These methods fail to accurately reflect the complex three-dimensional pathological changes surrounding the teeth. While CBCT technology provides high-resolution three-dimensional anatomical data, achieving true three-dimensional quantification is possible. However, establishing a standardized and reliable analytical method using this data has been a long-standing technical challenge.

[0051] In view of this situation, the present invention discloses a standardized three-dimensional periodontal attachment quantification method. Figure 1 As shown, the following steps are included:

[0052] The cementum-enamel boundary was demarcated, the tooth model was divided into the crown and root, and the total root surface area was determined;

[0053] Sensitivity analysis was performed using a sequence of candidate thresholds, and the optimal diagnostic threshold was determined in combination with the facet completeness criterion;

[0054] Based on the optimal diagnostic threshold, the absolute attachment area and relative attachment area ratio are calculated and output.

[0055] pass Figure 1 The embodiment provides an end-to-end complete technical solution encompassing multiple innovative steps, achieving standardized three-dimensional quantification of periodontal attachment area for the first time, thereby resolving the following core issues in the prior art:

[0056] (1) Fundamental limitations of two-dimensional imaging: It completely overcomes the problem of two-dimensional X-ray films (such as periapical films and panoramic films) widely used in clinical practice that cannot perform true three-dimensional quantitative evaluation due to image overlap, geometric distortion and information loss;

[0057] (2) Ambiguity of the starting point of three-dimensional analysis: This solves the problem of lack of standardized methods to accurately define the effective analysis area of ​​the tooth root (i.e., how to accurately segment the crown and root) when performing analysis on a three-dimensional model;

[0058] (3) Lack of three-dimensional quantitative standards: This solves the problem that in three-dimensional space, there is neither a recognized geometric criterion to determine "effective attachment" nor an objective method to determine the key parameters required for calculation (such as distance threshold).

[0059] Next, combine Figure 2 The complete technical process shown in the figure provides a detailed description of the technical solution of the present invention.

[0060] 1. Data Preparation and Guided Labeling of CEJ Feature Points

[0061] The starting point of this process is a high-quality 3D model and critical, guided manual annotations.

[0062] Reference Figure 3 , which shows the operation interface of a typical 3D interactive software (such as 3D Slicer). In this embodiment, the cementum-enamel boundary is demarcated, specifically including the following steps:

[0063] Model segmentation: Segmentation technology is used to extract the 3D surface model of the target tooth and its surrounding alveolar bone from the patient's CBCT data. This is the basis for all subsequent calculations.

[0064] Guided annotation: In this interactive interface, multiple predefined sparse anatomical landmarks are annotated along the contour of the cementoenamel junction (CEJ) of the target tooth model using an input device such as a mouse; Figure 3 As shown in , in this embodiment, 8 points are taken as an example, and these points may include 4 main points at the mesial, distal, buccal, and lingual sides, and turning points at four axis angles;

[0065] Data Export: After annotation, the software exports the segmented tooth model, alveolar bone model (e.g., as an STL file), and a feature point file containing the 3D coordinates of eight points (e.g., as an FCSV file) for subsequent automated processing. This step efficiently converts the operator's anatomical experience into digital signals.

[0066] 2. Automated High-Fidelity CEJ Curve Generation

[0067] From this step on, the process is completely taken over by background automation programs (such as Python scripts) to transform the sparse points into precise anatomical boundaries.

[0068] Reference Figure 4 ,This figure illustrates the core processing of the background program, which is also the subsequent process of calibrating the cementum-enamel boundary, specifically:

[0069] Data reading: The program first reads the tooth model file exported in step 1 and the FCSV file containing the coordinates of the 8 landmark points;

[0070] Initial curve fitting: The program applies a cubic B-spline interpolation algorithm to eight sparse anatomical landmarks to automatically fit a continuous, smooth, and closed three-dimensional spatial curve, which is an idealized mathematical expression of the CEJ.

[0071] Accurate surface projection: This is key to ensuring anatomical accuracy. Using a nearest neighbor algorithm, the program projects or adsorbs the generated 3D spatial curve onto the actual surface of the target tooth model, resulting in a final CEJ curve composed entirely of tooth surface vertices that accurately conforms to the anatomical form.

[0072] 3. Precise crown-root segmentation based on CEJ

[0073] After obtaining the precise CEJ line, the system can use it as a basis for standardized definition of the analysis area.

[0074] Reference Figure 5 , which shows the segmentation result. In this embodiment, segmenting the tooth model into crown and root specifically includes the following steps:

[0075] Model segmentation: The system uses the final CEJ curve generated in step 2 as the cutting boundary;

[0076] Region division: Through an algorithm (for example, combined with the determination of the long axis direction of the tooth), the original complete tooth model is accurately and non-overlappingly divided into two independent parts: the crown model and the root model;

[0077] Parameter calculation: The program automatically calculates the total surface area of ​​the root model, recorded as A_total_root. This value will be used as the "denominator" in the subsequent calculation of the relative attachment ratio. The accuracy of the calculation is due to the standardization process in the first two steps.

[0078] 4. Calculation of attachment area based on the “surface integrity criterion”

[0079] This step defines the specific geometric rules for determining "effective attachment" in the present invention. Figure 6 , which intuitively explains the calculation principle.

[0080] Judgment subject: The object of calculation is each tiny triangular face on the tooth root model;

[0081] "Surface integrity" criterion: For any triangular facet on the tooth root model, calculate the closest distances (d1, d2, d3) from the three vertices (v1, v2, v3) to the surface of the alveolar bone model. The necessary and sufficient condition for a facet to be considered an "attached facet" is that the three distances d1, d2, and d3 must all be less than or equal to a given distance threshold d.

[0082] Example: Figure 6As shown in , if the distance between all three vertices of a patch is less than d, it is counted in the attachment area; if two of the vertices of a patch meet the condition, but the distance d' between the third vertex is greater than d, then the patch is not counted in the attachment area. This strict criterion ensures the geometric stability and continuity of the calculated area.

[0083] 5. Data-driven determination of optimal diagnostic thresholds

[0084] This step is the most creative part of the present invention, as it solves the core problem of how to scientifically and objectively determine the distance threshold d in step 4.

[0085] Reference Figure 7 , the figure shows the whole process of threshold optimization, specifically:

[0086] Sensitivity analysis: The system does not use a fixed threshold d, but sets a sequence of candidate thresholds (for example, from 0.1mm to 2.0mm). Then, the system performs the attachment area calculation based on the "surface completeness" criterion described in step 4 for each candidate threshold in the candidate threshold sequence through a loop;

[0087] Curve generation: After completing the cycle, the system obtains a series of "threshold-area" data pairs and plots them into "area-threshold" sensitivity curves;

[0088] Inflection point optimization: Automated mathematical analysis of the geometry of the "area-threshold" sensitivity curve is performed to calculate and find the point with the maximum curvature on the curve as the knee point. This point physically represents the most significant transition boundary from "closely attached" to "generally adjacent";

[0089] Threshold determination: The horizontal coordinate value corresponding to the inflection point is objectively and automatically determined as the only optimal diagnostic threshold T_optimal for this calculation.

[0090] 6. Final Quantization and Output

[0091] Finally, the system uses T_optimal determined for the current case in step 5 to perform the calculation in step 4 to obtain the final absolute attachment area A_attached, and further calculates the relative attachment area ratio R_attached, which is presented to the doctor together with the 3D visualization results.

[0092] and Figure 1 Corresponding to the method described above, the embodiment of the present invention also provides a standardized three-dimensional periodontal attachment quantification system for Figure 1The specific implementation of the method, a standardized three-dimensional periodontal attachment quantification system provided by the embodiment of the present invention can be applied to a computer terminal or various mobile devices, specifically including:

[0093] The root analysis region definition module is used to calibrate the cementum-enamel boundary, segment the tooth model into the crown and root, and determine the total root surface area;

[0094] An attachment geometry determination module is used to perform sensitivity analysis using a candidate threshold sequence and determine the optimal diagnostic threshold in combination with a surface integrity criterion;

[0095] The result integration and output module is used to calculate and output the absolute attachment area and the relative attachment area ratio according to the optimal diagnostic threshold.

[0096] In summary, combined with specific experimental cases, the key innovations and beneficial effects of this embodiment are summarized as follows:

[0097] A. The end-to-end, standardized three-dimensional quantitative technology system is completely different from a single path: it completely overcomes the fundamental defects of traditional two-dimensional imaging in terms of dimensionality, accuracy and quantification capabilities, and fills the long-standing lack of standardized three-dimensional assessment methods in this field; this invention realizes the standardization of the entire process from three-dimensional data input to objective quantitative indicator output for the first time, making accurate and repeatable three-dimensional assessment of periodontal attachment possible.

[0098] B. Analysis process including standardized crown-root segmentation: The existing technology is overly simplified based on single-point judgment, which can easily misjudge non-supporting geometric neighbors as attachments, resulting in inaccurate results; the present invention adopts a stricter "three-vertex" constraint to ensure that the area included in the area is topologically continuous and stable, effectively filtering out noise and pseudo-attachments, and significantly improving the accuracy of the calculation results.

[0099] C. Specific attachment judgment criteria based on "surface integrity": This solves the technical defect that the curve fitted only by sparse points may have slight deviations from the actual anatomical surface ("hanging" or "cutting in"), thereby causing geometric inaccuracies; the present invention ensures that the final output CEJ curve has an absolute tooth-dissecting surface, which guarantees the accuracy and effectiveness of all downstream based on this curve, and the results are true and reliable.

[0100] D. Built-in data-driven mechanism for determining optimal diagnostic thresholds: Existing technologies rely on manually preset thresholds, which are subject to significant subjectivity and uncertainty, resulting in unreliable and incomparable results. This invention transforms threshold selection from "subjective specification" to "objective optimization," eliminating the subjectivity of parameter selection and ensuring the objectivity, repeatability, and scientific validity of measurement results.

[0101] Therefore, the technical solution of the present invention meets the requirements of novelty, creativity and practicality for patent examination. Specifically:

[0102] The novelty of this invention lies in the fact that it is not an extension or improvement of existing technologies (such as 2D radiographs), but rather it creates a completely new, complete, and unprecedented 3D periodontal attachment quantification technology system. The overall architecture of this technology system and the core processing modules it contains are both proposed and implemented for the first time. Specifically, this invention organically integrates the following three independent innovative links into a seamless, automated workflow for the first time:

[0103] 1) Standardized root analysis area definition: This is the first time a standardized CEJ (cementum-enamel junction) localization method based on operator sparse guidance and computer-automated projection has been proposed and implemented, enabling accurate and repeatable segmentation of the crown and root, providing a clear anatomical boundary for subsequent calculations;

[0104] 2) Specific attachment geometry: For the first time, "face integrity" is defined and applied as a geometric criterion for determining attachment. That is, a triangle must have all three vertices that meet the distance condition at the same time to be considered validly attached.

[0105] 3) Objective determination of calculation parameters: For the first time, a data-driven method for automatically optimizing the optimal diagnostic threshold was proposed and implemented. The optimal calculation parameters were dynamically determined for each case by analyzing the mathematical characteristics of the "area-threshold" sensitivity curve (such as the point of maximum curvature).

[0106] The creativity of this invention lies in its systematic top-level design and the integration of original solutions to a series of sub-problems. Faced with the huge gap between raw 3D data and final quantitative indicators, those skilled in the art could not foresee that such a set of interconnected standardized processes could be constructed:

[0107] 1) Creativity in System Construction: This approach identified three logically necessary challenges, each lacking standard answers in existing technologies: "determining the analysis scope," "determining attachment relationships," and "determining calculation parameters." Innovative solutions were provided for each, ultimately integrating them into an automated "assembly line." This systematic, end-to-end solution design itself is highly creative.

[0108] 2) Creativity of Each Module's Solutions: As previously mentioned, each module, whether the "sparse guided projection" CEJ localization method, the "surface integrity" criterion, or the "curvature-based threshold optimization" method, presents a non-obvious, innovative technical solution tailored to the specific problem it addresses. Through this innovative combination, the present invention fundamentally defines "how to perform standardized three-dimensional periodontal attachment assessment," filling a technological gap in this field.

[0109] The practicality of this invention lies in its transformation of a complex diagnostic process previously reliant on subjective experience, estimation, and two-dimensional imaging into an objective, accurate, and automated three-dimensional quantitative analysis process. It can provide clinicians with unprecedented, precise data on the condition of a patient's periodontal supporting tissues, directly contributing to personalized precision medicine. The system is simple to operate, provides reliable results, and seamlessly integrates into existing digital oral workflows, possessing high clinical application value and broad market prospects.

[0110] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0111] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A standardized three-dimensional periodontal attachment quantification method, characterized in that: The following steps are involved: The cementum-enamel boundary was demarcated, the tooth model was divided into the crown and root, and the total root surface area was determined; Sensitivity analysis was performed using a sequence of candidate thresholds, and the optimal diagnostic threshold was determined in combination with the facet completeness criterion; Based on the optimal diagnostic threshold, the absolute attachment area and relative attachment area ratio are calculated and output.

2. A standardized three-dimensional periodontal attachment quantification method according to claim 1, characterized in that: Demarcating the cementum-enamel boundary includes the following steps: Using segmentation technology, a 3D surface model of the target tooth and its surrounding alveolar bone is extracted from the patient's CBCT data; For the target tooth model, multiple predefined sparse anatomical landmarks are marked along the contour of the cementum-enamel junction; The cubic B-spline interpolation algorithm is applied to multiple sparse anatomical landmarks to automatically fit a continuous, smooth and closed three-dimensional spatial curve; Through the nearest neighbor algorithm, the three-dimensional space curve is projected or adsorbed onto the real surface of the target tooth model to obtain a final CEJ curve that is completely composed of tooth surface vertices and fits the anatomical morphology.

3. A standardized three-dimensional periodontal attachment quantification method according to claim 2, characterized in that: Segmenting the tooth model into crowns and roots involves the following steps: Using the final CEJ curve as the cutting boundary, the original complete tooth model is split into two independent parts without overlap: the crown model and the root model; Calculate the total surface area of ​​the tooth root model and record it as A_total_root.

4. A standardized three-dimensional periodontal attachment quantification method according to claim 3, characterized in that: A sensitivity analysis using a candidate threshold sequence is performed, which includes the following steps: For any triangular facet on the tooth root model, calculate the closest distances between the three vertices and the surface of the alveolar bone model; If the closest distances between the three vertices are all less than or equal to a given distance threshold, the triangle is counted into the attachment area; Through a loop, an attachment area calculation is performed for each candidate threshold in the candidate threshold sequence.

5. A standardized three-dimensional periodontal attachment quantification method according to claim 1, characterized in that: Determining the optimal diagnostic threshold involves the following steps: Based on a series of "threshold-area" data pairs obtained after sensitivity analysis, draw an "area-threshold" sensitivity curve; An automated mathematical analysis was performed on the geometric morphology of the "area-threshold" sensitivity curve. The point with the maximum curvature on the curve was calculated and found as the inflection point. The horizontal coordinate value corresponding to the inflection point was determined as the optimal diagnostic threshold T_optimal.

6. A standardized three-dimensional periodontal attachment quantification system, which executes a standardized three-dimensional periodontal attachment quantification method according to any one of claims 1 to 5, characterized in that: include: The root analysis region definition module is used to calibrate the cementum-enamel boundary, segment the tooth model into the crown and root, and determine the total root surface area; An attachment geometry determination module is used to perform sensitivity analysis using a candidate threshold sequence and determine the optimal diagnostic threshold in combination with a surface integrity criterion; The result integration and output module is used to calculate and output the absolute attachment area and the relative attachment area ratio according to the optimal diagnostic threshold.

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