CN109875713B

CN109875713B - Method for measuring distance from anterior mandibular tooth root tip to mandibular median lingual side tube

Info

Publication number: CN109875713B
Application number: CN201910227183.3A
Authority: CN
Inventors: 张雨; 黄定明; 陆倩; 高原; 谭学莲; 傅裕杰; 汪鎏
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2019-03-25
Filing date: 2019-03-25
Publication date: 2023-12-22
Anticipated expiration: 2039-03-25
Also published as: CN109875713A

Abstract

The invention discloses a method for measuring the distance from the tip of the anterior mandibular root to the lateral canal of the mandibular median tongue, which comprises the following steps in sequence: s1, shooting a pre-operation CBCT image; s2, establishing a space rectangular coordinate system; s3, establishing straight line equations y1 and y2; s4, recording the foot drop coordinates D (x ', y ', z '); s5, judging whether the point D is on an actual MLC pipeline segment, if so, calculating the distance between the point C and the point D to obtain D', and if not, executing the step S6; s6, calculating the distance between the point A and the point C and the distance between the point B and the point C, and taking the smaller value of the two distances as d'. The three-dimensional distance, especially the shortest space distance, between the anterior mandibular root tip and the MLC can be accurately measured by adopting the scheme, the safety of root tip operation can be conveniently guaranteed, and meanwhile, the scheme has the characteristics of simplicity in operation, high ranging efficiency and capability of being repeated in a large number.

Description

Method for measuring distance from anterior mandibular tooth root tip to mandibular median lingual side tube

Technical Field

The invention relates to the technical field of medical measurement, in particular to a method for measuring the distance from the tip of a mandibular anterior tooth to a mandibular median lingual side tube.

Background

Root canal therapy is one of the most common oral clinical diseases, but is the most common effective method for treating the diseases at present, but due to the restrictions of many factors such as anatomy of root canal system, degree of infection of root canal itself and the like, the probability of 6% -32% of treatment failure still exists in root canal therapy, and the failure rate of non-operative root canal re-treatment is higher than 20% -80%. For cases where periapical lesions do not heal for a long time, a non-surgical retreatment scheme is difficult, and a plurality of primary root canal treatments such as periapical cysts exist after failure, the periapical surgery becomes the last alternative for curing diseases and preserving suffering teeth. In recent years, with the general application of microscope, ultrasonic technology and biological materials in root tip surgery, the success rate of the root tip surgery can reach more than 90 percent.

Modern root tip surgery controls infection in the root canal by cutting and tightly sealing the root tip segment of the root canal with biological materials such as MTA, blocking the traffic of the root canal system with periapical and periodontal tissues. The operation steps mainly comprise incision and valve design, valve turning and bone removal, root tip scraping and cutting, root tip pouring preparation and pouring filling, and valve resetting and suturing. When the affected teeth are located in the anterior mandibular region, since the thickness of the alveolar bone is the smallest and there is at least 1 sublingual artery penetrating the lingual cortex and walking to the cheek side through MLC (mandibular median lingual tube, median lingual canals), there is a possibility that when the operations such as flap deboning, root apex scraping and root apex cutting are performed, there is no caution, the patient may die by choking bleeding due to fracture of the sublingual artery. Although the CBCT technology is adopted at present, the accurate distance between the MLC and the mandibular root tip is difficult to measure in the same plane by the existing preoperative CBCT data, and the nearest point to the lower anterior tooth is not always at the end of the pipeline visible by CT, so that the actual shortest distance between the affected root tip and the MLC cannot be directly measured by the conventional CBCT data.

Disclosure of Invention

Aiming at the problem of insufficient data in the existing clinical image aiming at the root tip surgery operation, the invention provides a method for measuring the distance from the anterior mandibular root tip to the central mandibular lingual side tube, and the three-dimensional distance, especially the shortest space distance, between the anterior mandibular root tip and the MLC can be accurately measured by adopting the scheme, so that the safety of the root tip surgery is conveniently ensured, and meanwhile, the scheme also has the characteristics of simplicity in operation, high ranging efficiency and capability of being repeated in a large number.

The technical means of the scheme is as follows, a method for measuring the distance from the anterior mandibular root tip to the mandibular median lingual side tube comprises the following steps in sequence:

s1, shooting a pre-operation CBCT image;

s2, establishing a space rectangular coordinate system in the obtained image, and marking the starting point coordinates of the MLC walk type: a (x 1, y1, z 1), dead point coordinates: b (x 2, y2, z 2) and the lower anterior apillary coordinate: c (x 3, y3, z 3);

s3, establishing a straight line equation y1 of A, B points to obtain a straight line equation y2, wherein the straight line equation y2 is as follows: a straight line equation passing through the point C and perpendicular to the straight line where the straight line equation is y 1;

s4, recording the vertical foot coordinates as D (x ', y ', z '), wherein the point D is the intersection point of a straight line with a straight line equation of y1 and a straight line with a straight line equation of y2;

s5, judging whether the point D is on an actual MLC pipeline segment, if so, calculating the distance between the point C and the point D, wherein the distance between the point C and the point D is the shortest vertical distance D' from the tip of the lower front tooth to the MLC, and finishing three-dimensional space distance measurement, and if not, performing step S6;

and S6, calculating the distance between the point A and the point C and the distance between the point B and the point C, and taking the smaller value of the two distances as the shortest vertical distance d' from the lower front root tip to the MLC to finish three-dimensional space distance measurement.

Aiming at the root tip surgery, as the surgery area usually relates to anatomical structures such as sublingual artery, genitourinary vascular bundle, maxillary sinus, mandibular nerve canal and the like, the proposal aims at measuring the space distance between the affected root tip and the anatomical structures through CBCT imaging data, if the radius D of the surgery range is larger than D 'when the surgery is adopted aiming at the shortest vertical distance D', the better planning of the surgery area can be realized, and the effects of avoiding injuring the important anatomical structures during the surgery and ensuring the life safety and quality of patients are achieved.

Compared with the direct measurement of the distance from the lower anterior tooth tip MLC on CBCT, the method can break through the limitation that the root tip and the MLC model-moving section are not in the same plane, and the accurate distance value can not be measured or the distance can not be measured at all because the planes of the root tip and the MLC model-moving section are far away, so that the distance from the root tip of the lower anterior tooth and even any other mandibular tooth to the MLC can be measured with possibility and feasibility.

The method is non-invasive operation, a patient only needs to shoot a preoperative CBCT image according to conventional operation, an invasive procedure is not needed to be accepted, no harm is caused to the patient, and ethical specification is met.

The whole implementation process of the method depends on the conventional and common software, and a common doctor can complete corresponding calculation under the condition of zero foundation, so that the clinician can conveniently grasp the position relation of the lower front teeth and the MLC, the preoperative risk assessment of the root tip operation of the lower front teeth area is facilitated, the preoperative planning and the intraoperative timely adjustment of the operation area range are facilitated, the serious medical outcome caused by injuring the walked neurovascular structure in the MLC pipeline is avoided, and the safety of the operation is facilitated to be ensured.

Specifically, step S2 may be performed by manual identification, or may be performed by self-contained reader software in a general CBCT optical disc, for example, by opening a PACS browser, but as a person skilled in the art, since there are different CBCT optical discs and the manufacturing is performed by using shooting devices of different manufacturers, the reader software is not limited to relying on a PACS browser; the steps S3 and S4 can be completed through manual calculation, and can also be performed by using existing mathematical software, such as Matlab software; in step S5, although there are various ways of actually routing the MLC pipe, most of the ways are linear or substantially linear, so for determining whether the point D is on the line segment of the MLC pipe, it can be determined whether the point D falls on the line with the linear equation of y1 and is located between the two points A, B, and for the case that the point D falls outside the end of the line segment with the end point of A, B, the D' is obtained in step S6. Further, for the case that the point D falls on the line segment with the end point A, B, it can be determined whether the point D is in the actual MLC pipeline according to the actual CBCT image obtained in the step S1, so as to be a preferred solution, the shortest vertical distance D' between the point C and the point D can be corrected by using the actual CBCT image obtained in the step S1, and the specific correction parameter depends on the actual running condition of the MLC pipeline in the actual CBCT image.

The specific implementation process of the scheme can be as follows: the device is mainly divided into three parts, wherein the first part is a pre-operation CBCT image and matched image reading software which are clinically shot by a patient. After the patient regularly shoots the pre-operation CBCT image, the image is opened by adopting corresponding image reading software such as a PACS browser, and the starting point coordinates (x 1, y1, z 1), the dead point coordinates (x 2, y2, z 2) and the lower front root tip coordinates (x 3, y3, z 3) of the MLC walk are positioned.

The second part is to record the start point coordinates (x 1, y1, z 1) and the stop point coordinates (x 2, y2, z 2) of the MLC walk by adopting Matlab three-dimensional reconstruction software, and establish a linear equation y1=b1+a1x (a1+.0) for two points on a straight line. Then, a lower anterior apex coordinate (X3, y3, z 3) is entered, and a straight line equation y2=b2+a2x (a2+.0) perpendicular to the straight line y1 and passing through the lower anterior apex (X3, y3, z 3) is calculated. The vertical intersection of the straight lines y1, y2 was obtained, and the vertical foot coordinates were recorded as D (x ', y ', z '). The distance between the foot-pendant D (x ', y', z ') and the lower anterior root tip (x 3, y3, z 3) is calculated and denoted as D', which is the shortest vertical distance from the lower anterior root tip to the MLC in three dimensions. It should be noted that after the MLC start point coordinates (x 1, y1, z 1), dead point coordinates (x 2, y2, z 2) and lower anterior root tip coordinates (x 3, y3, z 3) are entered, matlab software can calculate the straight line y1, the straight line y2, the foot drop coordinates, the distance d' between the foot drop and the root tip by itself, without additional manual calculation, and the operation is simple. The Matlab software can directly optimize the process of calculating d' by using a pre-written programming document for distance calculation. The program content written by the document may be as follows:

％％

clc

clear

close all

％％

％AB＝[x2-x1,y2-y1,z2-z1]；

％OP＝[x-x3,y-y3,z-z3]；

X1＝x1；

Y1＝x2；

Z1＝x3；

X2＝x2；

Y2＝y2；

Z2＝z2；

X3＝x3；

Y3＝y3；

Z3＝z3；

syms X Y Z

eq1＝(x2-x1)*(x-x3)+(y2-y1)*(y-y3)+(z2-z1)*(z-z3)；

eq2＝(x-x1)/(x2-x1)-(y-y1)/(y2-y1)；

eq3＝(y-y1)/(y2-y1)-(z-z1)/(z2-z1)；

[x,y,z]＝solve(eq1,eq2,eq3,x,y,z)；

subs(x)；

subs(y)；

subs(z)；

x0＝double(x)；

y0＝double(y)；

z0＝double(z)；

d＝sqrt((x3-x0)^2+(y3-y0)^2+(z3-z0)^2)；

D＝double(d)；

plot3([x1,x2],[y1,y2],[z1,z2])；

hold on

plot3([x,x3],[y,y3],[z,z3])；

as shown in programming content, x1, y1, z1, x2, y2, z2, x3, y3 and z3 values corresponding to the lower front root tip coordinates of the MLC start and stop points are directly input in the document content, all the document content is fully selected and copied into a Matlab input frame, and the distance value d 'between the MLC and the lower front root tip is obtained, wherein the d' value is the shortest vertical distance from the lower front root tip to the MLC. When the distance from the other front root tip (x 4, y4, z 4) to the MLC is required to be calculated, the root tip coordinate points x3, y3 and z3 are directly replaced by x4, y4 and z4 in the programming content, the steps are repeated, and the shortest vertical distance from the affected root tip to the MLC can be obtained by copying the whole content to a Matlab input frame. And similarly, when the space distance from another mandibular median lingual side tube to a certain lower anterior root tip is required to be measured, the coordinate value of the MLC starting point is correspondingly modified and then substituted into the Matlab input frame.

Meanwhile, aiming at the actual clinical situation that the MLC pipeline is actually a linear pipeline with limited length or a nonlinear pipeline very close to a straight line, the three-dimensional space distance from the lower front root tip to the MLC is obtained by using Matlab software and a preprogrammed distance calculation document, so that the method is very fast, convenient and simple. And Matlab software can automatically generate visual three-dimensional images of the point-line relations after D 'is calculated, and whether the shortest distance D (x', y ', z') from the tip of the lower front tooth to the line where the MLC is located is on the actual MLC pipeline segment can be directly judged from the images. If in the schematic of Matlab software output, there is a case where two line segments intersect, d' is the shortest vertical distance from the lower anterior root tip to the MLC; if not (two line segments have no intersection point in the schematic diagram), the Excel table is adopted to directly calculate the distance D between the MLC starting point and the lower front root point (D is larger than the distance between the lower front root point and the foot drop D (x ', y ', z ').

When the Matlab space image shows that the shortest vertical distance point from the lower front root tip to the MLC is not on the MLC line segment, the third part of operation is needed to be performed by means of Excel software (the Excel table can be pre-programmed with a calculation formula) to obtain the distance d between the MLC starting point and the lower front root tip. The Excel table preset formula may be: d= SQRT ((A2-E2)/(2+ (B2-F2)/(2+ (C2-G2)). The table is divided into three parts: MLC end point (start point or stop point) coordinates, root tip coordinates to be calculated, and two-point distance value d. When the table is used, the specific numerical value of the shortest clinical distance d can be automatically generated in the column of the 'two-point distance d' only by correspondingly inputting the coordinates of the root tip of the target and the start and stop points of the MLC: firstly, recording coordinates of an MLC starting point and a lower front root tip, and pressing an Enter key to obtain a distance d1 from the root tip to an MLC starting point in a 'two-point distance d' column; and replacing the starting point coordinates with the point coordinates, repeating the operation to obtain the distance d2 from the root tip to the dead point, and taking the smaller value of d1 and d2 as the numerical value of the shortest clinical distance d' from the lower anterior tooth to the MLC.

In summary, the overall operation steps are summarized as follows: firstly, coordinate points of an MLC starting point and a lower front root tip are read on CBCT, and the three coordinate values are respectively substituted into a programming document correspondingly. And copying the document content into the Matlab input box to obtain a three-dimensional space diagram and a shortest vertical distance d'. The whole process can be completed directly by Matlab and a programming document without complicated manual calculation, and the programming document can be directly used on any computer without additionally installing programming software, so that the operation is more convenient and quick.

It should be noted that if the MLC tunnel has terminated before reaching the shortest distance point with the lower anterior root tip (i.e., the foot drop D), then the distance between the two points of the MLC start dead point and the lower anterior root tip should be calculated as the "clinical shortest distance" D. The operation steps are basically identical to the d' calculation process: firstly, reading coordinates, substituting coordinate values into a programming document, copying document contents to a Matlab input frame to obtain a three-dimensional space diagram and a shortest vertical distance d', wherein the vertical foot is seen to be positioned outside a straight line y1 (namely, two straight lines of a schematic diagram are not intersected) in the three-dimensional space diagram, at the moment, respectively inputting a root tip coordinate point and an MLC starting point to an Excel calculation table, and pressing an Enter key to obtain a distance value between the root tip coordinate point and the starting point.

The further technical scheme is as follows:

as described above, since Matlab software can output intuitive images according to inputted numerical values, for a linear or near-linear MLC pipe, it is set to: the steps S3 to S5 are based on Matlab software.

As described above, since there are few nonlinear MLC tubes, when it is determined from the CBCT image obtained in step S1 that the straight line passing through the two points A, B cannot correctly represent the MLC tube running, in order to facilitate the data accuracy of the finally obtained d' in the surgical guidance, it is set as follows: in the step S2, the coordinates of the three points A, B, C are identified by a reader, and in the step S5, it is determined whether the point D is implemented on the actual MLC pipeline segment by the following method: and (3) comparing the coordinates of the D point obtained in the step (S4) with the coordinate values of the points of the MLC pipeline line segment in the reader, wherein the D point is not on the actual MLC pipeline segment when the coordinate values of the points of the MLC pipeline segment do not contain points which are the coordinate values of the D point, and the D point is on the actual MLC pipeline segment when the coordinate values of the points of the MLC pipeline segment contain points which are the coordinate values of the D point. When the coordinate values of each point of the MLC pipe line segment do not include the point which is the coordinate value of the D point, according to the actual situation, D 'may be obtained by using step S6 or the obtained D' may be corrected to obtain the final D ', and the specific correction method may be to obtain the point adjacent to the D point on the MLC pipe line segment according to the coordinate value of the D point, and then calculate the obtained coordinate value of the adjacent point to obtain D'.

As an implementation scheme which is easy to operate and popularize and has clear data generalization, the following steps are set: the step S6 is realized by Excel software.

The invention has the following beneficial effects:

the distance from the anterior mandibular root tip to the MLC, which is measured by the method, is the distance of a three-dimensional space concept, and accords with the maximum operation range which needs to be paid attention to protecting important anatomical structures such as nerve vascular bundles running in a pipeline in the actual operation process of the root tip operation of the lower anterior mandibular root region, wherein the radius D of the operation range is larger than D' (the shortest vertical distance from the affected root tip to the MLC) and D (the two-point distance from the affected root tip to the starting point or the dead point of the MLC).

The method is a non-invasive operation, a patient only needs to shoot a preoperative CBCT image according to the conventional operation, and the method does not need to accept an invasive procedure and accords with ethical and ethical specifications.

The software adopted by the method is basically conventional software, a common doctor can use the software by himself under the condition of zero foundation, programming content and a table calculation formula are all drawn, the doctor can copy the software according to the operation steps, the clinician can conveniently grasp the position relation between the lower front teeth and the MLC, the preoperative risk assessment of the root tip operation of the lower front teeth area is convenient for preoperative planning and timely adjusting the operation area range in operation, serious medical fatalities caused by injuring the nerve vascular structure of the walking type in the MLC pipeline are avoided, and the safety of the operation is facilitated to be ensured.

Detailed Description

The present invention will be described in further detail with reference to examples, but the structure of the present invention is not limited to the following examples.

Example 1:

the embodiment provides a method for measuring the distance from the apex of the anterior root of the mandibular tooth to the lateral canal of the mandibular median tongue, which comprises the following steps sequentially carried out:

s1, shooting a pre-operation CBCT image;

Example 2:

the embodiment provides a specific implementation case based on Matlab software on the basis of embodiment 1:

for a patient A who is about to undergo 41-terminal surgery, the patient MLC start point coordinates (2, -30, -26), dead point coordinates (1, -33, -30), and right lower median root tip coordinates (-3, -39, -18) are first read on CBCT data.

Substituting the coordinate points into the programming document correspondingly:

％％

clc

clear

close all

％％

％AB＝[x2-x1,y2-y1,z2-z1]；

％OP＝[x-x3,y-y3,z-z3]；

x1＝2；

y1＝-30；

z1＝-26；

x2＝1；

y2＝-33；

z2＝-30；

x3＝-3；

y3＝-39；

z3＝-18；

syms x y z

eq1＝(x2-x1)*(x-x3)+(y2-y1)*(y-y3)+(z2-z1)*(z-z3)；eq2＝(x-x1)/(x2-x1)-(y-y1)/(y2-y1)；

eq3＝(y-y1)/(y2-y1)-(z-z1)/(z2-z1)；

[x,y,z]＝solve(eq1,eq2,eq3,x,y,z)；

subs(x)；

subs(y)；

subs(z)；

x0＝double(x)；

y0＝double(y)；

z0＝double(z)；

d＝sqrt((x3-x0)^2+(y3-y0)^2+(z3-z0)^2)；D＝double(d)；

plot3([x1,x2],[y1,y2],[z1,z2])；

hold on

plot3([x,x3],[y,y3],[z,z3])；

the right results bar automatically generates the value of the vertical distance d '(d' =13.04 mm) and the three-dimensional space diagram by copying all the document contents into the "fx >" dialog box of Matlab software. The intersection of the two segments is seen (i.e., the foot drop is on the MLC segment), so that the d' value is the shortest clinical and theoretical distance to the MLC that needs to be noted in 41 root apex surgery, suggesting that all surgery operations are performed beyond a radius of 1.3cm from 41 root apices, so as to avoid inadvertently damaging important anatomical structures in the MLC and causing life hazards to the patient.

Example 3:

the embodiment provides a specific implementation case based on Matlab software and excel software based on the embodiment 1:

for a patient A who is going to perform a row 31 cusp operation, the patient MLC start coordinates (2, -30, -26), stop coordinates (1, -33, -30), right inferior median apocynum coordinates (-3, -39, -18), left inferior median apocynum coordinates (2, -39, -18) are first read on CBCT data. The shortest clinical and theoretical distance from 41 root tips to MLC was 13.04mm as obtained in example 1. Similarly, the 41-tooth coordinates are replaced by 31-tooth coordinates (2, -39, -18) in the document content, and the coordinate points are respectively substituted into the programming document in a corresponding way:

％％

clc

clear

close all

％％

％AB＝[x2-x1,y2-y1,z2-z1]；

％OP＝[x-x3,y-y3,z-z3]；

x1＝2；

y1＝-30；

z1＝-26；

x2＝1；

y2＝-33；

z2＝-30；

x3＝2；

y3＝-39；

z3＝-18；

syms x y z

eq1＝(x2-x1)*(x-x3)+(y2-y1)*(y-y3)+(z2-z1)*(z-z3)；

eq2＝(x-x1)/(x2-x1)-(y-y1)/(y2-y1)；

eq3＝(y-y1)/(y2-y1)-(z-z1)/(z2-z1)；

[x,y,z]＝solve(eq1,eq2,eq3,x,y,z)；

subs(x)；

subs(y)；

subs(z)；

x0＝double(x)；

y0＝double(y)；

z0＝double(z)；

d＝sqrt((x3-x0)^2+(y3-y0)^2+(z3-z0)^2)；

D＝double(d)；

plot3([x1,x2],[y1,y2],[z1,z2])；

hold on

plot3([x,x3],[y,y3],[z,z3])；

the shortest vertical distance d 'from 31 teeth to the line of the MLC was 12.00mm, but since the drop foot was seen to lie outside the MLC line segment in the three-dimensional schematic (i.e. the median lingual line segment had no intersection with the vertical line segment), the d' value was the theoretical shortest distance from 31 teeth to the line y1 of the MLC, rather than the "shortest clinical distance d" that needs to be noted in the actual operation of the procedure. The excel table continues to be used to calculate d. At this time, the two-point distances d1 and d2 from the 31 teeth to the starting and ending points of the MLC need to be calculated simultaneously, and a smaller value is taken as the shortest distance data from the 31 teeth to the MLC, which is clinically needed.

An Excel table with a preset calculation formula is opened. Inputting MLC starting point coordinates (2, -30, -26) and 31 root tip coordinates (2, -39, -18), and pressing an Enter key to obtain a distance d1=12.04 mm from the 31 root tip to the MLC starting point in a 'two-point distance d' column; the start point coordinates were replaced by the stop point coordinates (1, -33, -30), and the operation was repeated to obtain a 31 root tip to stop point distance d2=12.04 mm, so that the 31 tooth clinical shortest distance d from the MLC actual canal was 12.04mm.

The table is divided into three parts: the MLC endpoint (start or stop) coordinates, the root tip coordinates to be calculated, and the two-point distance value d, preset the formula d+=SQRT ((A2-E2)/(2+ (B2-F2)/(2+ (C2-G2)). When the method is used, the specific numerical value of d can be automatically generated in the column of the distance d between two points only by correspondingly inputting the coordinates of the root tip of the target and the start and stop points of the MLC.

As can be seen from the calculation result, the nearest distance point from the 41 root tip to the MLC is on the line segment, so the shortest spatial distance d' =shortest clinical distance d=13.04 mm from the 41 root tip to the MLC; whereas the shortest clinical distance d=12.04 mm of 31 root tip to MLC was calculated since the closest distance point of 31 root tip to MLC was not on its line segment. All surgical procedures were suggested to be performed beyond a radius of 1.3cm from the 41 root tip and beyond a radius of 1.2cm from the 31 root tip, so as not to inadvertently damage important anatomical structures within the MLC, causing patient life-threatening.

Example 4:

for a patient B who is about to undergo a right anterior mandibular (43-41 teeth) root tip surgery, the patient's MLC start coordinates (2, -26, -31), dead center coordinates (1, -35, -34), right inferior apillary coordinates (-11, -32, -22), right inferior apillary coordinates (-6, -37, -18) and right inferior median apillary coordinates (-3, -39, -17) are first read on CBCT data.

The distance from the lower right cuspid to the MLC was first calculated using Matlab. Substituting the coordinate points into the programming document correspondingly:

％％

clc

clear

close all

％％

％AB＝[x2-x1,y2-y1,z2-z1]；

％OP＝[x-x3,y-y3,z-z3]；

x1＝-2；

y1＝-26；

z1＝-31；

x2＝1；

y2＝-35；

z2＝-34；

x3＝-11；

y3＝-32；

z3＝-22；

syms x y z

eq1＝(x2-x1)*(x-x3)+(y2-y1)*(y-y3)+(z2-z1)*(z-z3)；

eq2＝(x-x1)/(x2-x1)-(y-y1)/(y2-y1)；

eq3＝(y-y1)/(y2-y1)-(z-z1)/(z2-z1)；

[x,y,z]＝solve(eq1,eq2,eq3,x,y,z)；

subs(x)；

subs(y)；

subs(z)；

y0＝double(y)；

z0＝double(z)；

d＝sqrt((x3-x0)^2+(y3-y0)^2+(z3-z0)^2)；

D＝double(d)；

plot3([x1,x2],[y1,y2],[z1,z2])；

hold on

plot3([x,x3],[y,y3],[z,z3])；

the right results bar automatically generates the value of the vertical distance d '(d' =16.38 mm) and the three-dimensional space diagram by copying all the document contents into the "fx >" dialog box of Matlab software. The intersection of the two segments is seen (i.e. the drop foot point is on the lingual line segment), so it is known that d' =16.38 mm is the shortest clinical and theoretical distance from 43 root tips to MLC.

Then correspondingly replacing the 43 root tip coordinate values in the document content with 42 root tip coordinate values,

the following are provided:

％％

clc

clear

close all

％％

％AB＝[x2-x1,y2-y1,z2-z1]；

％OP＝[x-x3,y-y3,z-z3]；

x1＝-2；

y1＝-26；

z1＝-31；

x2＝1；

y2＝-35；

z2＝-34；

x3＝-6；

y3＝-37；

z3＝-18；

syms x y z

eq1＝(x2-x1)*(x-x3)+(y2-y1)*(y-y3)+(z2-z1)*(z-z3)；

eq2＝(x-x1)/(x2-x1)-(y-y1)/(y2-y1)；

eq3＝(y-y1)/(y2-y1)-(z-z1)/(z2-z1)；

[x,y,z]＝solve(eq1,eq2,eq3,x,y,z)；

subs(x)；

subs(y)；

subs(z)；

y0＝double(y)；

z0＝double(z)；

d＝sqrt((x3-x0)^2+(y3-y0)^2+(z3-z0)^2)；

D＝double(d)；

plot3([x1,x2],[y1,y2],[z1,z2])；

hold on

plot3([x,x3],[y,y3],[z,z3])；

repeating the above steps, copying all document contents into the "fx >" dialog box of Matlab software, and automatically generating the numerical value (d '=17.41 mm) and three-dimensional space diagram of the vertical distance d' by the right result column. The intersection of the two segments is seen (i.e. the drop foot point is on the lingual line segment), so it is known that d' =17.41 mm is the shortest clinical and theoretical distance from 42 root tips to MLC.

Similarly, the shortest clinical and theoretical distances from the 41 root tip to the MLC were found for d '=17.88 mm, and thus, the shortest clinical distances from the 43, 42, 41 teeth to the MLC were all the vertical distances d' (theoretical shortest distance) from the three root tip points to the straight line where the MLC was located, and were 16.38mm, 17.41mm, and 17.88mm, respectively, and the root tip in the right mandibular anterior tooth was closest to the MLC but not the right lower anterior incisors (this information was not obtained by simply relying on CBCT information). Thus, during 43-41 root tip surgery, when the surgical field is moved to the 43 tooth field, the vigilance should be improved rather, and it cannot be considered that the teeth further from the midline of the mandible are safer to perform the root tip surgery. It is recommended that the surgical procedure be performed within a range of more than 1.6cm from the 43 root tip, more than 1.7cm from the 42 root tip, and more than 1.8cm from the 41 root tip, so as not to inadvertently damage the important anatomy in the MLC, resulting in life-threatening patients.

The foregoing is a further detailed description of the invention in connection with specific preferred embodiments, and it is not intended that the invention be limited to these descriptions. Other embodiments of the invention, which are apparent to those skilled in the art to which the invention pertains without departing from the technical solution of the invention, shall be covered by the protection scope of the corresponding invention.

Claims

1. A method of measuring anterior mandibular root tip to mandibular median lingual canal distance comprising the steps of, in sequence:

s1, shooting a pre-operation CBCT image;

s6, calculating the distance between the point A and the point C and the distance between the point B and the point C, taking the smaller value of the two distances as the shortest vertical distance d' from the tip of the lower front tooth to the MLC, and completing three-dimensional space distance measurement;

for the case that the point D falls on a line segment with two points of A, B, judging whether the point D is in an actual MLC pipeline according to the actual CBCT image obtained in the step S1, and correcting the shortest vertical distance D' between the point C and the point D by using the actual CBCT image obtained in the step S1: and step S2 is completed by adopting reader software, and the coordinate range covered by the actual walking of the MLC pipeline in the actual CBCT image is calibrated by utilizing the reader software, and the correction value is matched through the coordinate range.

2. A method of measuring anterior mandibular root tip to mandibular median lingual tube distance according to claim 1, wherein steps S3 to S5 are based on Matlab software.

3. The method according to claim 1, wherein in the step S2, the coordinates of the three A, B, C points are identified by a reader, and in the step S5, the determination of whether the point D is implemented on the actual MLC line segment is performed by: and (3) comparing the coordinates of the D point obtained in the step (S4) with the coordinate values of the points of the MLC pipeline line segment in the reader, wherein the D point is not on the actual MLC pipeline segment when the coordinate values of the points of the MLC pipeline segment do not contain points which are the coordinate values of the D point, and the D point is on the actual MLC pipeline segment when the coordinate values of the points of the MLC pipeline segment contain points which are the coordinate values of the D point.

4. A method of measuring anterior mandibular root tip to mandibular median lingual duct distance according to any one of claims 1 to 3, wherein step S6 is implemented using Excel software.