CN104546151A - Numerical control laser automatic tooth preparation method and equipment thereof - Google Patents

Abstract

The invention relates to a numerical control laser automatic tooth preparation method and equipment thereof. The equipment contains an intraoral spatial digitizer, a dental laser, a numerical control laser tooth preparation control system intraoral working end, an oromaxillo-facial region cone-beam CT machine, a computer, a tooth fixator and a negative pressure aspirator. The computer is respectively connected with the intraoral spatial digitizer, the dental laser, the oromaxillo-facial region cone-beam CT machine and the negative pressure aspirator. The dental laser is connected with the numerical control laser tooth preparation control system intraoral working end which is connected with the tooth fixator. The equipment can replace part of manual operation of a doctor. A traditional mechanical grinding apparatus is replaced with laser. Clinical therapy operative level of grass-roots doctors can be effectively raised within a short period of time, and diagnosis and treatment efficiency and quality can be improved.

Description

Digital control laser automatization tooth preparation method and equipment

Technical field

The present invention relates to a kind of tooth preparation method, be specifically related to a kind of digital control laser automatization tooth preparation method, the invention still further relates to a kind of digital control laser automatization tooth preparation equipment.

Background technology

1, the manual tooth preparation technology of clinical practice both at home and abroad at present.

Traditional manual tooth preparation pattern is difficult to reach the standard-required in textbook and Clinical Practice.The level entirety of the manual tooth preparation of China is on the low side (according to relevant expert's statistics, qualification rate accounts for about 40%).In China, high-caliber oral cavity doctor's quantity is comparatively deficient.Meanwhile, cultivate a high-caliber clinician, often need the time for many years.Above-mentioned factor causes jointly " see that tooth is expensive, see that tooth is difficult ".In addition, therefore, need research and development badly brand-new, automatization, intelligent clinical tooth preparation technology, substitute traditional manual mode.

Traditional manual tooth preparation pattern is difficult to reach the standard-required in textbook and Clinical Practice.The level entirety of the manual tooth preparation of China is on the low side (estimate according to relevant expert, qualification rate accounts for about 40%).In China, high-caliber oral cavity doctor's quantity is comparatively deficient.Meanwhile, cultivate a high-caliber clinician, often need the time for many years.Above-mentioned factor causes jointly " see that tooth is expensive, see that tooth is difficult ".In addition, therefore, need research and development badly brand-new, automatization, intelligent clinical tooth preparation technology, substitute traditional manual mode.

2, hard tooth tissue laser cutting technique

Some business-like Er:YAG and Er:YSGG laser instrument are for simple hand-held laser type tooth preparations such as tooth body removing the necrotic tissue and cavity preparations, but the coarse injustice of the dental surface after Er laser cutting, micro-crack may be accompanied to produce, be difficult to the high-precision requirement meeting Oral Repair tooth preparation.Laser cutting dental hard tissue has that precision is high, in active set, the feature such as hot injury is little, can cut under low-down energy density, its to enamel, Dentinal ablation threshold be 0.6 ~ 2.2,0.3 ~ 1.4J/cm ², be expected to the instrument becoming high precision numerical control tooth preparation.But existing bibliographical information laser is (0.05 ~ 3.6) × 10 to enamel, Dentinal cutting rate ^-3, (0.12 ~ 1.90) × 10-3mm ³/ s, lower than high speed turbine mobile phone (about 1mm ³/ s).Meanwhile, laser is different from traditional mechanical bistrique, does not have FORCE FEEDBACK in operation, is unfavorable for operating along with the position experiencing cutting element, direction and attitude etc., is unfavorable for the precision controlling cutting path.

3, about small space laser optical path automatic control technology

At present, some digital control laser scanning optical path control technologys have been there are abroad.As the three-dimensional laser processing software TbPs400 of the three-dimensional laser processing coordinative composition of equipments of German large laser device fabrication business TRUMPF company, but only effective to the cutting of pipe and rectangular pipe fittings, and narrowly, this is a kind of Laser Processing of 2.5 dimensions.And the three-dimensional laser processing software FORMA that the famous laser equipment manufacturing enterprise PRIMAINUSTRIE S.P.A of Italy provides can only for the work station as IBMRISC Systern16000.The PEPSPentacut3D diced system of CAMTEK company of Britain not only shortens the duration, higher required precision can also be provided to bring huge competitive advantage simultaneously, but such software price is expensive, does not possess the market of popularity.On the 11 Beijing International Machine Tool exhibition (CIMT2009) in April, 2009, by (comprising big nation's laser to 20 exhibition Duo Jia laser equipment manufacturers, Wuhan Fa Lilai, unite hundred to surpass, unite the domestic well-known laser equipment manufacturer such as Pu Ruima) investigation, what find exhibition manufacturer's exhibition is substantially all two-dimensional laser cutting machine bed, only have Shanghai unity Pu Ruima company to put on display three-dimensional laser cutting machine bed that model is SESAMO2545, but that its supporting dimension laser cutting automatic programming software adopts is the PEPS PentaCut that Camtek company of Britain develops, illustrate domestic to dimension laser cutting equipment at present, especially the research of automatic programming system is not also very ripe, constrain the popularization of dimension laser cutting technology.

For the tooth preparation in small space this in oral cavity, realize the automatic control of laser optical path, there is not yet and relevant report.

Summary of the invention

The object of this invention is to provide a kind of digital control laser automatization tooth preparation method, the part manual operations of doctor can be substituted, substitute traditional mechanical grinding apparatus with laser, effectively can improve the clinical treatment operating technology level of basic unit doctor at short notice, improve diagnosis and treatment efficiency and quality.The object of this invention is to provide a kind of digital control laser automatization tooth preparation equipment.

In order to achieve the above object, the present invention has following technical scheme:

A kind of digital control laser automatization of the present invention tooth preparation method, comprises the following steps:

1) obtain the three-dimensional surface scan-data of target tooth bizet with spatial digitizer in mouth, obtain target tooth bizet three-dimensional data with oromaxillo-facial region conical beam CT machine, above-mentioned two groups of data are stored separately, so that subsequent read operations;

2) with tooth preparation CAD software, registration is carried out to above-mentioned two groups of data, and be unified in same coordinate system, extract Tooth preparation edge, definition dental preparations design parameter on the computer screen, segmentation enamel, dentin and pulp cavity, complete the Dummy modeling of dental preparations, finally result is stored as STL formatted data;

3) according to step 2) the dental preparations dummy model data that obtain, laser tooth preparation CAM software generates the Cutting Process relevant parameter of the focal beam spot diameter of laser in tooth preparation process, spot motion path, speed automatically, and outputs in digital control laser tooth preparation control system;

4) with silicone rubber, tooth position localizer is fixed on target tooth and nearly middle adjacent teeth far away, and the silicone rubber removed around target tooth bizet, the overall three-dimensional data of tooth position localizer and target tooth is again obtained with spatial digitizer in mouth, utilize step 2) in software Tooth preparation dummy model data and whole scanning data are carried out registration, by the locating dowel on the localizer of tooth position, the tooth of working end in the oral cavity of digital control laser tooth preparation control system and tooth position localizer is closed face opening be rigidly connected, realize target tooth bizet, in the oral cavity of tooth position localizer and digital control laser tooth preparation control system, the unification of the spatial relation of working end is fixed,

5) in step 2) in the coordinate system that formed, laser tooth preparation CAM software is utilized to complete the accurate focusing of laser at target tooth initial position, control laser facula and automatically complete tooth preparation process according to the scanning pattern set and scanning speed, on the localizer of tooth position, negative pressure suction device is installed simultaneously, removes tooth chip in real time;

6) tooth preparation is completed, working end and tooth position localizer in orderly release digital control laser tooth preparation control system oral cavity in patient oral cavity.

Wherein, described tooth preparation CAD software comprises data read module, pretreatment module, data fusion module, constraint modeling module, post-processing module.

Wherein:

Described data read module comprises:

1) CT data reconstruction: CT image reconstruction three-dimensional data is read in tooth preparation CAD software, carries out illumination, play up.

2) scan-data is rebuild: by the three-dimensional data obtained target tooth scanning acquisition three-dimensional surface scan-data and CT machine, and reads in software storage, facilitates subsequent read operations;

Described pretreatment module comprises:

1) integration region curved surface obtains: first obtain three-dimensional surface scan-data model to target tooth and carry out Region dividing, be divided into integration region and non-fused region, non-fused region point set maintains static, and adopts the neck edge line drawing algorithm based on illumination scan to carry out blend surface cutting extraction to three-dimensional surface scan-data model;

2) based on man-machine interactively initial registration: according to 3 reorientation principles, a coordinate relation can be set up at 3, the model that spatial digitizer obtains in CT machine and mouth picks up characteristic of correspondence point and be no less than three, by the alignment of characteristic point alignment implementation model, difference feature point for calibration s on the model that spatial digitizer obtains in CT machine and mouth _i, s ' _iby s ' _i=s _ir+T calculates geometric transformation R between characteristic point, T, matrix is acted on the model that in CT machine and mouth, spatial digitizer obtains and carry out initial transformation, this method greatly can reduce translation error and rotation error between follow-up ICP Model registration, for accuracy registration provides good initial value;

3) based on ICP algorithm accuracy registration: pass through initial registration, ICP algorithm is adopted to carry out accuracy registration, position registration between model is exactly that the model that obtained by spatial digitizer scanning in mouth and CT machine obtain rotation between three-dimensional data model coordinate systems and translation, make the spacing of homologous points minimum, by calculating the optimum spin matrix R of kth time iteration ^kwith translation vector T ^k, make CT model N reach f (R, T) to minimum with the least square approximation object function of scan model M after spatial variations:

$f(R,T)=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\left|\right|v_i^{\′}-({\mathrm{Rv}}_i+T)\left|\right|}^2\→\min$

Described data fusion module comprises:

1) differential coordinate is set up: introduce Laplace operator coefficient matrix L, guarantees the conversion carrying out between cartesian coordinate and differential coordinate with multiplication of matrices form: Δ=LV, L=I-D ^-1a

Wherein Δ={ δ _ibe grid differential coordinate, D is diagonal matrix, wherein D _ii=d _i, A is the adjacency matrix of grid;

2) constraints is set up: CT machine obtains spatial digitizer in three-dimensional data model deformation curved surface N and mouth and scans after the model obtained fixes curved surface M registration, the method that grid significance combines with Morse theory is realized the extraction of remarkable characteristic on scan model M, the closest approach of the Feature point correspondence that search M extracts in N is as constraints;

3) distortion iterative processing is merged:

In the process that deformation surface N is out of shape to fixing curved surface M, single distortion easily produces the distortion of grid form, therefore the strategy of a kind of successive ignition distortion is taken, by single Deformation partition for repeatedly to carry out, after iterative strategy not only makes distortion, grid is naturally mild, and avoid grid selfing phenomenon, each deflection b is:

$b=\frac{1}{n-k},k=\mathrm{0,1}...n-1$

4) weight coefficient design is out of shape: quantize and assess the degree of closeness between deformation point and impact point by design weight matrix, by give a definition:

w _i=w _d(k,d)×w _a(α)

Wherein, w _d(k, d) is distance weighting function, and k is current iteration number of times, and d is current deformation point g _iwith target distortion point v _ibetween distance, w _a(α) be Angular weight function, α is deformation point g _idirection of normal and scan model center of gravity to the directions of rays l of deformation point _ibetween angle;

5) model meshes is rebuild: above-mentioned weight matrix W is introduced linear equation and energy function:

$\left(\begin{array}{c}L\\ {\mathrm{wI}}_{m\×m}\end{array}\right)V^{\′}=L^{\′}{V}^{\′}=\left(\begin{array}{c}\mathrm{\δ}\\ \mathrm{wC}\end{array}\right)$

$E\left(V^{\′}\right)={\left|\right|L^{\′}{V}^{\′}-\mathrm{\δ}\left|\right|}^2+\underset{j\∈C}{\mathrm{\Σ}}w{\left|\right|v_j^{\′}-c_j\left|\right|}^2$

When energy function minimizes, warp mesh, for reaching expection deformation position, is taked the precomputation of decomposing based on Cholesky to accelerate to solve, is tried to achieve x ' respectively in solution procedure, y ', z ';

Described constraint modeling module comprises:

1) spatial point cloud data axis extracts: utilize the optimization method of space line matching to carry

Get the long axis of tooth of tooth, if direction vector is S=(m, n, p) and crosses point (x in space ₀, y ₀, z ₀) linear equation be

$\frac{x-x_0}{m}=\frac{y-y_0}{n}=\frac{z-z_0}{p}$

Wherein x ₀, y ₀, z ₀for passing through the D coordinates value of point, m, n, p are that the coordinate of direction vector represents,

According to Least squares approach principle: error equation is $f(S_{t1},S_{t2},S_{t3})={\mathrm{\Σ}}_{i=0}^R({S_{t1}}^2+{S_{t2}}^2{+S_{t3}}^2)$ , wherein, S _t1, S _t2, S _t3be respectively a little at the error component of X axis, Y-axis, Z-axis direction, N is number a little,

Utilize this ternary quadratic nonlinearity equation of optimum gradient method solution, optimized direction vector (m, n, p) can be obtained, utilize this direction vector and known mid point to obtain straight line, be tooth body axis;

2) space curve projection: with line segment encryption sciagraphy, neck edge line is separated into data point set, pointwise projects to CT machine along curvature direction and obtains on three-dimensional data model, connects each subpoint and is drop shadow curve;

3) discrete model is biased: utilize the offset algorithm bias model based on point, the multidirectional amount on grid vertex is by classification of type and give different weights, and biased direction accounting equation is as follows:

${\stackrel{\→}{V}}_{\mathrm{Offset}}=\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{W}_j\·{\stackrel{\→}{N}}_{i,j}$

Wherein V _offsetfor the biased direction of point, 1 ... n is the triangular plate number that summit one is enclosed, W _jfor the weighted value that dissimilar triangular plate is different, N _ijenclose triangular plate method corresponding respectively for summit one to vow, by obtaining biased later model at each some direction of normal bias point;

4) model constrained equation group analysis and solving: by analysis constraint moulded dimension chain relation, list model constrained equation:

$\left\{\begin{array}{c}\frac{L}{2}=L_1+L_x+L_3\\ H=L_2+L_y+L_4\\ \tan \mathrm{\α}=\frac{L_x}{L_y}\end{array}\right.$

Wherein, L ₁, L ₂, α is parameterized three variate-values, for appointment tooth, H, L and L4 are fixed value, and when parameter value is given, equation group is the equation group containing three unknown numbers, uniquely can determine one group of L by known three equations _x, L _yand L ₃value, thus can uniquely determine Tooth preparation model, by solving this constraint equation, can Confirming model each several part locus;

5) constraints model parametric modeling: utilize the method for parameterization operations to drive Tooth preparation modeling, and utilize the parametrization based on historic villages and towns implementation model to on-the-fly modify;

Described post-processing module comprises:

That detects constraint meets situation: by calculating angle and the dimension constraint in each cross section of Tooth preparation generated, detecting the error size generating Tooth preparation model, and utilizing the distribution situation of color cloud picture formal intuition display error.

Wherein, described is gone on record according to model construction order together with parameter value by parameterization operations based on historic villages and towns, formation model structure tree, and enclose labelling for each operation, when parameter modification of dimension, find the operation of correspondence markings and start to re-construct model according to structure history with new parameter value with this, completing the renewal of new model.

A kind of digital control laser automatization of the present invention tooth preparation equipment, comprise spatial digitizer in mouth, dental lasers, working end in digital control laser tooth preparation control system oral cavity, oromaxillo-facial region conical beam CT machine, computer, Dental anchor, vacuum extractor, described computer respectively with spatial digitizer in mouth, dental lasers, oromaxillo-facial region conical beam CT machine, vacuum extractor connects, dental lasers is connected with working end in digital control laser tooth preparation control system oral cavity, in digital control laser tooth preparation control system oral cavity, working end is connected with Dental anchor.

Wherein, in described digital control laser tooth preparation control system oral cavity, working end comprises light-conducting arm, reflecting mirror lid, locator interface, base, motor cabinet, oscillating motor one, oscillating motor two, two galvanometer system, linear electric motors, condenser lens seat, line slideway, grating sensor, described light-conducting arm is fixed on the left side of base, reflecting mirror lid is positioned at the end of light-conducting arm, locator interface is positioned under reflecting mirror lid, described line slideway is positioned on base, condenser lens seat is positioned on line slideway, grating sensor is positioned under condenser lens seat, described linear electric motors are fixed on base, oscillating motor one, oscillating motor two is fixed on motor cabinet, two galvanometer system and oscillating motor one, oscillating motor two connects.

Wherein, described pair of galvanometer system comprises galvanometer one, galvanometer two, condenser lens, reflecting mirror, described galvanometer one is positioned at the below of galvanometer two, condenser lens is between galvanometer two and reflecting mirror, galvanometer one, galvanometer two drive rotate respectively by oscillating motor one, oscillating motors two, and condenser lens is driven by linear electric motors.

Owing to taking above technical scheme, the invention has the advantages that:

The present invention can substitute the part manual operations of doctor, substitutes traditional mechanical grinding apparatus, effectively can improve the clinical treatment operating technology level of basic unit doctor at short notice, improve diagnosis and treatment efficiency and quality with laser.

Accompanying drawing explanation

Fig. 1 is the flow chart of digital control laser automatization of the present invention tooth preparation method;

Fig. 2 is the model constrained schematic diagram of Tooth preparation of the present invention;

Fig. 3 is the block diagram of digital control laser automatization of the present invention tooth preparation equipment;

Fig. 4 is the schematic diagram of working end in digital control laser tooth preparation control system oral cavity of the present invention;

Fig. 5 is the schematic diagram of the two galvanometer system of the present invention.

In figure: 1, light-conducting arm; 2, reflecting mirror lid; 3, locator interface; 4, lens mount pad; 5, grating sensor; 6, line slideway; 7, linear electric motors; 8, base; 9, two-lens system; 10, oscillating motor one; 11, oscillating motor two; 12, motor cabinet; 13, galvanometer one; 14, galvanometer two; 15, condenser lens; 16, reflecting mirror; 17, target tooth; 18, laser beam.

Detailed description of the invention

Following examples for illustration of the present invention, but are not used for limiting the scope of the invention.

Of the present invention a kind of digital control laser automatization tooth preparation method, is made up of following steps:

1) obtain the three-dimensional surface scan-data of target tooth bizet with spatial digitizer in mouth, obtain target tooth bizet three-dimensional data with oromaxillo-facial region conical beam CT machine, above-mentioned two groups of data are stored separately, so that subsequent read operations;

2) with tooth preparation CAD software, registration is carried out to above-mentioned two groups of data, and be unified in same coordinate system, extract Tooth preparation edge, definition dental preparations design parameter on the computer screen, segmentation enamel, dentin and pulp cavity, complete the Dummy modeling of dental preparations, finally result is stored as STL formatted data;

3) according to step 2) the dental preparations dummy model data that obtain, laser tooth preparation CAM software generates the Cutting Process relevant parameter such as focal beam spot diameter, spot motion path, speed of laser in tooth preparation process automatically, and outputs in digital control laser tooth preparation control system;

What above-mentioned laser tooth preparation adopted is that the method successively removed obtains Tooth preparation, and whole path planning comprises two links, and one is slicing delamination, and one is that the cross section contour obtained for slicing delamination generates efficient cut path;

Rapid section layering link: be first that the tri patch in the threedimensional model of tooth body STL formatted data is divided into groups, tri patch is divided into some groups according to from the different of its crossing incisal plane, the tri patch in each group all intersects with same incisal plane; Then, by the tri patch in each group and incisal plane cap, each tri patch and incisal plane phase intersection obtain a crossing line segment, according to the seriality of the threedimensional model intermediate cam dough sheet of STL formatted data, a undirected closed cross section contour can be formed, without the need to carrying out topological structure reconstruction to tri patch or sorting to obtained intersection section;

The efficient cut coordinates measurement link of cross section profile: the method first adopting straight line to fill solves cut region and fills straight line intersection line segment, calculate laser cut line, then these lines of cut are sorted and Region dividing, the cutting zone of complexity is divided into the cutting zone of little dullness, the efficient cut path of final generation;

4) with silicone rubber, tooth position localizer is fixed on target tooth and nearly middle adjacent teeth far away, and removes the silicone rubber around target tooth bizet.Again obtain the overall three-dimensional data of tooth position localizer and target tooth with spatial digitizer in mouth, utilize step 2) in software Tooth preparation dummy model data and whole scanning data are carried out registration.By the locating dowel on the localizer of tooth position, the tooth of working end in the oral cavity of digital control laser tooth preparation control system and tooth position localizer is closed face opening be rigidly connected, in the oral cavity of realize target tooth bizet, tooth position localizer and digital control laser tooth preparation control system, the unification of the spatial relation of working end is fixed;

5) in step 2) in the coordinate system that formed, laser tooth preparation CAM software is utilized to complete the accurate focusing of laser at target tooth initial position, control laser facula and automatically complete tooth preparation process according to the scanning pattern set and scanning speed, on the localizer of tooth position, negative pressure suction device is installed simultaneously, removes tooth chip in real time;

Laser tooth preparation CAM software work mode is as follows:

The auto-focusing of initial position: first, lens position initializes, and makes lens get back to initial zero position; Then, the peak coordinate figure (greatest z value of target tooth) of target tooth can be obtained by target Yahoo STL model; Finally, the distance of the final movement of lens can be calculated according to the parameter of the obtained the highest coordinate of tooth and laser optical path, the focal position of laser finally can be made to drop on the peak position of target tooth exactly;

Tooth preparation automation process controls: in laser tooth preparation path planning, adopts the mode of straight cuts at the uniform velocity to carry out tooth preparation.The cutting path of laser forms by the cut line segment of different length.Realize the at the uniform velocity cutting of laser, need to carry out interpolation processing to cut line segment, laser scanning line segment by different length is divided into Small Distance cut point, by Inverse Kinematics computing closely spaced cut point D coordinates value is transferred to the galvanometer one in laser work head, the angular displacement of galvanometer two and the displacement of the lines of lens.Because galvanometer and lens all adopt direct drive mode, the point of the cut after can controlling laser spot follow interpolation so the linear electric motors of galvanometer one, galvanometer two motor and lens move simultaneously, finally realize laser and at the uniform velocity realize cutting along the cutting path of planning, complete automatic tooth preparation process;

6) tooth preparation is completed, working end and tooth position localizer in orderly release digital control laser tooth preparation control system oral cavity in patient oral cavity.

Described tooth preparation CAD software comprises data read module, pretreatment module, data fusion module, constraint modeling module, post-processing module.See Fig. 1.

Wherein:

Described data read module comprises:

1) CT data reconstruction: CT image reconstruction three-dimensional data is read in tooth preparation CAD software, carries out illumination, play up.

2) scan-data is rebuild: by the three-dimensional data obtained target tooth scanning acquisition three-dimensional surface scan-data and CT machine, and reads in software storage, facilitates subsequent read operations;

Described pretreatment module comprises:

1) integration region curved surface obtains: first obtain three-dimensional surface scan-data model to the scanning of scanning target tooth and carry out Region dividing, be divided into integration region and non-fused region, non-fused region point set maintains static.The neck edge line drawing algorithm based on illumination scan is adopted to carry out blend surface cutting extraction to three-dimensional surface scan-data model, illumination scan is that the cost by evaluating each target to be searched obtains optimum search position, again from this search until final goal, thus omit a large amount of meaningless path, improve search efficiency;

2) based on man-machine interactively initial registration: according to 3 reorientation principles, a coordinate relation can be set up at 3, the model that spatial digitizer obtains in CT machine and mouth picks up characteristic of correspondence point and be no less than three, by the alignment of characteristic point alignment implementation model.Difference feature point for calibration s on the model that spatial digitizer obtains in CT machine and mouth _i, s ' _iby s ' _i=s _ir+T calculates geometric transformation R between characteristic point, T, matrix is acted on the model that in CT machine and mouth, spatial digitizer obtains and carry out initial transformation, this method greatly can reduce translation error and rotation error between follow-up ICP Model registration, for accuracy registration provides good initial value;

3) based on ICP algorithm accuracy registration: pass through initial registration, ICP algorithm is adopted to carry out accuracy registration, position registration between model is exactly that the model that obtained by spatial digitizer scanning in mouth and CT machine obtain rotation between three-dimensional data model coordinate systems and translation, make the spacing of homologous points minimum, by calculating the optimum spin matrix R of kth time iteration ^kwith translation vector T ^k, make CT model N reach f (R, T) to minimum with the least square approximation object function of scan model M after spatial variations:

$f(R,T)=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\left|\right|v_i^{\′}-({\mathrm{Rv}}_i+T)\left|\right|}^2\→\min$

Described data fusion module comprises:

1) differential coordinate is set up: introduce Laplace operator coefficient matrix L, guarantees the conversion carrying out between cartesian coordinate and differential coordinate with multiplication of matrices form:

Δ=LV,L=I-D ^-1A

Wherein Δ={ δ _ibe grid differential coordinate, D is diagonal matrix, wherein D _ii=d _i, A is the adjacency matrix of grid;

2) constraints is set up: CT machine obtains spatial digitizer in three-dimensional data model deformation curved surface N and mouth and scans after the model obtained fixes curved surface M registration, the method that grid significance combines with Morse theory is realized the extraction of remarkable characteristic on scan model M, the closest approach of the Feature point correspondence that search M extracts in N is as constraints;

3) distortion iterative processing is merged:

In the process that warp mesh N is out of shape to fixed mesh M, single distortion easily produces the distortion of grid form, therefore the strategy of a kind of successive ignition distortion is taken, by single Deformation partition for repeatedly to carry out, after iterative strategy not only makes distortion, grid is naturally mild, and avoid grid selfing phenomenon, each deflection b is:

$b=\frac{1}{n-k},k=\mathrm{0,1}...n-1$

4) weight coefficient design is out of shape: quantize and assess the degree of closeness between deformation point and impact point by design weight matrix, by give a definition:

w _i=w _d(k,d)×w _a(α)

Wherein, w _d(k, d) is distance weighting function, and k is current iteration number of times, and d is current deformation point g _iwith target distortion point v _ibetween distance, w _a(α) be Angular weight function, α is deformation point g _idirection of normal and scan model center of gravity to the directions of rays l of deformation point _ibetween angle;

5) model meshes is rebuild: above-mentioned weight matrix W is introduced linear equation and energy function:

$\left(\begin{array}{c}L\\ {\mathrm{wI}}_{m\×m}\end{array}\right)V^{\′}=L^{\′}{V}^{\′}=\left(\begin{array}{c}\mathrm{\δ}\\ \mathrm{wC}\end{array}\right)$

$E\left(V^{\′}\right)={\left|\right|L^{\′}{V}^{\′}-\mathrm{\δ}\left|\right|}^2+\underset{j\∈C}{\mathrm{\Σ}}w{\left|\right|v_j^{\′}-c_j\left|\right|}^2$

When energy function minimizes, warp mesh, for reaching expection deformation position, is taked the precomputation of decomposing based on Cholesky to accelerate to solve, is tried to achieve x ' respectively in solution procedure, y ', z ';

Described constraint modeling module comprises:

1) spatial point cloud data axis extracts: utilize the optimization method of space line matching to carry

Get the long axis of tooth of tooth, if direction vector is S=(m, n, p) and crosses point (x in space ₀, y ₀, z ₀) linear equation be

$\frac{x-x_0}{m}=\frac{y-y_0}{n}=\frac{z-z_0}{p}$

Wherein x ₀, y ₀, z ₀for passing through the D coordinates value of point, m, n, p are that the coordinate of direction vector represents,

According to Least squares approach errors of principles equation be $f(S_{t1},S_{t2},S_{t3})={\mathrm{\Σ}}_{i=0}^R({S_{t1}}^2+{S_{t2}}^2{+S_{t3}}^2)$ , wherein, S _t1, S _t2, S _t3be respectively a little at the error component of X axis, Y-axis, Z-axis direction, N is number a little,

Utilize this ternary quadratic nonlinearity equation of optimum gradient method solution, optimized direction vector (m, n, p) can be obtained, utilize this direction vector and known mid point to obtain straight line, be tooth body axis;

2) space curve projection: with line segment encryption sciagraphy, neck edge line is separated into data point set, pointwise projects to CT machine along curvature direction and obtains on three-dimensional data model, connects each subpoint and is drop shadow curve;

3) discrete model is biased: utilize the offset algorithm bias model based on point, the multidirectional amount on grid vertex is by classification of type and give different weights, and biased direction accounting equation is as follows:

${\stackrel{\→}{V}}_{\mathrm{Offset}}=\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{W}_j\·{\stackrel{\→}{N}}_{i,j}$

Wherein V _offsetfor the biased direction of point, 1 ... n is the triangular plate number that summit one is enclosed, W _jfor the weighted value that dissimilar triangular plate is different, N _ijenclose triangular plate method corresponding respectively for summit one to vow, by obtaining biased later model at each some direction of normal bias point;

4) model constrained equation group analysis and solving: by analysis constraint moulded dimension chain relation, list model constrained equation:

$\left\{\begin{array}{c}\frac{L}{2}=L_1+L_x+L_3\\ H=L_2+L_y+L_4\\ \tan \mathrm{\α}=\frac{L_x}{L_y}\end{array}\right.$

Wherein, L ₁, L ₂, α is parameterized three variate-values, for appointment tooth, H, L and L4 are fixed value, and when parameter value is given, equation group is the equation group containing three unknown numbers, uniquely can determine one group of L by known three equations _x, L _yand L ₃value, thus can uniquely determine Tooth preparation model, by solving this constraint equation, can Confirming model each several part locus, see Fig. 2;

5) constraints model parametric modeling: utilize the method for parameterization operations to drive Tooth preparation modeling, and utilize the parametrization based on historic villages and towns implementation model to on-the-fly modify;

Described post-processing module comprises:

That detects constraint meets situation: by calculating angle and the dimension constraint in each cross section of Tooth preparation generated, detecting the error size generating Tooth preparation model, and utilizing the distribution situation of color cloud picture formal intuition display error.

Wherein, described is gone on record according to model construction order together with parameter value by parameterization operations based on historic villages and towns, formation model structure tree, and enclose labelling for each operation, when parameter modification of dimension, find the operation of correspondence markings and start to re-construct model according to structure history with new parameter value with this, completing the renewal of new model.

See Fig. 3, a kind of digital control laser automatization of the present invention tooth preparation equipment, comprise spatial digitizer in mouth, dental lasers, working end in digital control laser tooth preparation control system oral cavity, oromaxillo-facial region conical beam CT machine, computer, Dental anchor, vacuum extractor, described computer respectively with spatial digitizer in mouth, dental lasers, oromaxillo-facial region conical beam CT machine, vacuum extractor connects, dental lasers is connected with working end in digital control laser tooth preparation control system oral cavity, in digital control laser tooth preparation control system oral cavity, working end is connected with Dental anchor.

See Fig. 4, in described digital control laser tooth preparation control system oral cavity, working end comprises light-conducting arm, reflecting mirror lid, locator interface, base, motor cabinet, oscillating motor one, oscillating motor two, two galvanometer system, linear electric motors, condenser lens seat, line slideway, grating sensor, described light-conducting arm is fixed on the left side of base, reflecting mirror lid is positioned at the end of light-conducting arm, locator interface is positioned under reflecting mirror lid, described line slideway is positioned on base, condenser lens seat is positioned on line slideway, grating sensor is positioned under condenser lens seat, described linear electric motors are fixed on base, oscillating motor one, oscillating motor two is fixed on motor cabinet, two galvanometer system and oscillating motor one, oscillating motor two connects.

See Fig. 5, described pair of galvanometer system comprises galvanometer one, galvanometer two, condenser lens, reflecting mirror, described galvanometer one is positioned at the below of galvanometer two, condenser lens is between galvanometer two and reflecting mirror, galvanometer one, galvanometer two drive rotate respectively by oscillating motor one, oscillating motors two, and condenser lens is driven by linear electric motors.

Obviously, above-mentioned enforcement of the present invention is only for example of the present invention is clearly described, and is not the restriction to embodiments of the present invention.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here cannot give exhaustive to all embodiments.Every belong to technical scheme of the present invention the apparent change of extending out or variation be still in the row of protection scope of the present invention.

Claims (7)

1. a digital control laser automatization tooth preparation method, is characterized in that comprising the following steps:

1) obtain the three-dimensional surface scan-data of target tooth bizet with spatial digitizer in mouth, obtain target tooth bizet three-dimensional data with oromaxillo-facial region conical beam CT machine, above-mentioned two groups of data are stored separately, so that subsequent read operations;

2) with tooth preparation CAD software, registration is carried out to above-mentioned two groups of data, and be unified in same coordinate system, extract Tooth preparation edge, definition dental preparations design parameter on the computer screen, segmentation enamel, dentin and pulp cavity, complete the Dummy modeling of dental preparations, finally result is stored as STL formatted data;

3) according to step 2) the dental preparations dummy model data that obtain, laser tooth preparation CAM software generates the Cutting Process relevant parameter of the focal beam spot diameter of laser in tooth preparation process, spot motion path, speed automatically, and outputs in digital control laser tooth preparation control system;

4) with silicone rubber, tooth position localizer is fixed on target tooth and nearly middle adjacent teeth far away, and the silicone rubber removed around target tooth bizet, the overall three-dimensional data of tooth position localizer and target tooth is again obtained with spatial digitizer in mouth, utilize step 2) in software Tooth preparation dummy model data and whole scanning data are carried out registration, by the locating dowel on the localizer of tooth position, the tooth of working end in the oral cavity of digital control laser tooth preparation control system and tooth position localizer is closed face opening be rigidly connected, realize target tooth bizet, in the oral cavity of tooth position localizer and digital control laser tooth preparation control system, the unification of the spatial relation of working end is fixed,

5) in step 2) in the coordinate system that formed, laser tooth preparation CAM software is utilized to complete the accurate focusing of laser at target tooth initial position, control laser facula and automatically complete tooth preparation process according to the scanning pattern set and scanning speed, on the localizer of tooth position, negative pressure suction device is installed simultaneously, removes tooth chip in real time;

6) tooth preparation is completed, working end and tooth position localizer in orderly release digital control laser tooth preparation control system oral cavity in patient oral cavity.

2. a kind of digital control laser automatization as claimed in claim 1 tooth preparation method, is characterized in that: described tooth preparation CAD software comprises data read module, pretreatment module, data fusion module, constraint modeling module, post-processing module.

3. a kind of digital control laser automatization as claimed in claim 2 tooth preparation method, is characterized in that:

Described data read module comprises:

1) CT data reconstruction: CT image reconstruction three-dimensional data is read in tooth preparation CAD software, carries out illumination, play up.

2) scan-data is rebuild: by the three-dimensional data obtained target tooth scanning acquisition three-dimensional surface scan-data and CT machine, and reads in software storage, facilitates subsequent read operations;

Described pretreatment module comprises:

1) integration region curved surface obtains: first obtain three-dimensional surface scan-data model to target tooth and carry out Region dividing, be divided into integration region and non-fused region, non-fused region point set maintains static, and adopts the neck edge line drawing algorithm based on illumination scan to carry out blend surface cutting extraction to three-dimensional surface scan-data model;

2) based on man-machine interactively initial registration: according to 3 reorientation principles, a coordinate relation can be set up at 3, the model that spatial digitizer obtains in CT machine and mouth picks up characteristic of correspondence point and be no less than three, by the alignment of characteristic point alignment implementation model, difference feature point for calibration s on the model that spatial digitizer obtains in CT machine and mouth _i, s ' _iby s ' _i=s _ir+T calculates geometric transformation R between characteristic point, T, matrix is acted on the model that in CT machine and mouth, spatial digitizer obtains and carry out initial transformation, this method greatly can reduce translation error and rotation error between successive iterations closest approach Model registration, for accuracy registration provides good initial value;

3) based on ICP algorithm accuracy registration: pass through initial registration, ICP algorithm is adopted to carry out accuracy registration, position registration between model is exactly that the model that obtained by spatial digitizer scanning in mouth and CT machine obtain rotation between three-dimensional data model coordinate systems and translation, make the spacing of homologous points minimum, by calculating the optimum spin matrix R of kth time iteration ^kwith translation vector T ^k, make CT model N reach f (R, T) to minimum with the least square approximation object function of scan model M after spatial variations:

$f(R,T)=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\left|\right|v_i^{\′}-({\mathrm{Rv}}_i+T)\left|\right|}^2\→\min$

Described data fusion module comprises:

1) differential coordinate is set up: introduce Laplace operator coefficient matrix L, guarantees the conversion carrying out between cartesian coordinate and differential coordinate with multiplication of matrices form: Δ=LV, L=I-D ^-1a

Wherein Δ={ δ _ibe grid differential coordinate, D is diagonal matrix, wherein D _ii=d _i, A is the adjacency matrix of grid;

2) constraints is set up: CT machine obtains spatial digitizer in three-dimensional data model deformation curved surface N and mouth and scans after the model obtained fixes curved surface M registration, the method that grid significance combines with Morse theory is realized the extraction of remarkable characteristic on scan model M, the closest approach of the Feature point correspondence that search M extracts in N is as constraints;

3) distortion iterative processing is merged:

In the process that deformation surface N is out of shape to fixing curved surface M, single distortion easily produces the distortion of grid form, therefore the strategy of a kind of successive ignition distortion is taken, by single Deformation partition for repeatedly to carry out, after iterative strategy not only makes distortion, grid is naturally mild, and avoid grid selfing phenomenon, each deflection b is:

$b=\frac{1}{n-k},k=\mathrm{0,1}...n-1$

4) weight coefficient design is out of shape: quantize and assess the degree of closeness between deformation point and impact point by design weight matrix, by give a definition:

w _i=w _d(k,d)×w _a(α)

Wherein, w _d(k, d) is distance weighting function, and k is current iteration number of times, and d is current deformation point g _iwith target distortion point v _ibetween distance, w _a(α) be Angular weight function, α is deformation point g _idirection of normal and scan model center of gravity to the directions of rays l of deformation point _ibetween angle;

5) model meshes is rebuild: above-mentioned weight matrix W is introduced linear equation and energy function:

$\left(\begin{array}{c}L\\ {\mathrm{wI}}_{m\×m}\end{array}\right)V^{\′}=L^{\′}{V}^{\′}=\left(\begin{array}{c}\mathrm{\δ}\\ \mathrm{wC}\end{array}\right)$

$E\left(V^{\′}\right)={\left|\right|L^{\′}{V}^{\′}-\mathrm{\δ}\left|\right|}^2+\underset{j\∈C}{\mathrm{\Σ}}w{\left|\right|v_j^{\′}-c_j\left|\right|}^2$

When energy function minimizes, warp mesh, for reaching expection deformation position, is taked the precomputation of decomposing based on Cholesky to accelerate to solve, is tried to achieve x ' respectively in solution procedure, y ', z ';

Described constraint modeling module comprises:

1) spatial point cloud data axis extracts: utilize the optimization method of space line matching to extract the long axis of tooth of tooth, if direction vector is S=(m, n, p) and crosses point (x in space ₀, y ₀, z ₀) linear equation be:

$\frac{x-x_0}{m}=\frac{y-y_0}{n}=\frac{z-z_0}{p}$

Wherein x ₀, y ₀, z ₀for passing through the D coordinates value of point, m, n, p are that the coordinate of direction vector represents,

According to Least squares approach errors of principles equation be $f(S_{t1},S_{t2},S_{t3})={\mathrm{\Σ}}_{i=0}^R({S_{t1}}^2+{S_{t2}}^2{+S_{t3}}^2)$ , wherein, S _t1, S _t2, S _t3be respectively a little at the error component of X axis, Y-axis, Z-axis direction, N is number a little,

Utilize this ternary quadratic nonlinearity equation of optimum gradient method solution, optimized direction vector (m, n, p) can be obtained, utilize this direction vector and known mid point to obtain straight line, be tooth body axis;

2) space curve projection: with line segment encryption sciagraphy, neck edge line is separated into data point set, pointwise projects to CT machine along curvature direction and obtains on three-dimensional data model, connects each subpoint and is drop shadow curve;

3) discrete model is biased: utilize the offset algorithm bias model based on point, the multidirectional amount on grid vertex is by classification of type and give different weights, and biased direction accounting equation is as follows:

${\stackrel{\→}{V}}_{\mathrm{Offset}}=\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{W}_j\·{\stackrel{\→}{N}}_{i,j}$

Wherein V _offsetfor the biased direction of point, 1 ... n is the triangular plate number that summit one is enclosed, W _jfor the weighted value that dissimilar triangular plate is different, N _ijenclose triangular plate method corresponding respectively for summit one to vow, by obtaining biased later model at each some direction of normal bias point;

4) model constrained equation group analysis and solving: by analysis constraint moulded dimension chain relation, list model constrained equation:

$\left\{\begin{array}{c}\frac{L}{2}=L_1+L_x+L_3\\ H=L_2+L_y+L_4\\ \tan \mathrm{\α}=\frac{L_x}{L_y}\end{array}\right.$

Wherein, L ₁, L ₂, α is parameterized three variate-values, for appointment tooth, H, L and L4 are fixed value, and when parameter value is given, equation group is the equation group containing three unknown numbers, uniquely can determine one group of L by known three equations _x, L _yand L ₃value, thus can uniquely determine Tooth preparation model, by solving this constraint equation, can Confirming model each several part locus;

5) constraints model parametric modeling: utilize the method for parameterization operations to drive Tooth preparation modeling, and utilize the parametrization based on historic villages and towns implementation model to on-the-fly modify;

Described post-processing module comprises:

That detects constraint meets situation: by calculating angle and the dimension constraint in each cross section of Tooth preparation generated, detecting the error size generating Tooth preparation model, and utilizing the distribution situation of color cloud picture formal intuition display error.

4. a kind of digital control laser automatization as claimed in claim 3 tooth preparation method, it is characterized in that: described is gone on record according to model construction order together with parameter value by parameterization operations based on historic villages and towns, formation model structure tree, and enclose labelling for each operation, when parameter modification of dimension, find the operation of correspondence markings and start to re-construct model according to structure history with new parameter value with this, completing the renewal of new model.

5. a digital control laser automatization tooth preparation equipment, it is characterized in that: comprise spatial digitizer in mouth, dental lasers, working end in digital control laser tooth preparation control system oral cavity, oromaxillo-facial region conical beam CT machine, computer, Dental anchor, vacuum extractor, described computer respectively with spatial digitizer in mouth, dental lasers, oromaxillo-facial region conical beam CT machine, vacuum extractor connects, dental lasers is connected with working end in digital control laser tooth preparation control system oral cavity, in digital control laser tooth preparation control system oral cavity, working end is connected with Dental anchor.

6. a kind of digital control laser automatization as claimed in claim 5 tooth preparation equipment, it is characterized in that: in described digital control laser tooth preparation control system oral cavity, working end comprises light-conducting arm, reflecting mirror lid, locator interface, base, motor cabinet, oscillating motor one, oscillating motor two, two galvanometer system, linear electric motors, condenser lens seat, line slideway, grating sensor, described light-conducting arm is fixed on the left side of base, reflecting mirror lid is positioned at the end of light-conducting arm, locator interface is positioned under reflecting mirror lid, described line slideway is positioned on base, condenser lens seat is positioned on line slideway, grating sensor is positioned under condenser lens seat, described linear electric motors are fixed on base, oscillating motor one, oscillating motor two is fixed on motor cabinet, two galvanometer system and oscillating motor one, oscillating motor two connects.

7. a kind of digital control laser automatization as claimed in claim 6 tooth preparation equipment, it is characterized in that: described pair of galvanometer system comprises galvanometer one, galvanometer two, condenser lens, reflecting mirror, described galvanometer one is positioned at the below of galvanometer two, condenser lens is between galvanometer two and reflecting mirror, galvanometer one, galvanometer two drive rotate respectively by oscillating motor one, oscillating motors two, and condenser lens is driven by linear electric motors.