# US 10,373,701 B2 · Methods and apparatuses for creating a statistical average model of an enamel-dentine junction

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- Number: US 10,373,701 B2
- Document ID: US10373701B2
- Status: Granted
- Kind: B2
- Application number: 14/540,457
- Filed: 2014-11-13
- Published: 2015-08-06
- Granted: 2019-08-06
- Earliest claimed: 2013-11-18
- Assignees: Nuctech Company Limited
- Applicants: Nuctech Company Limited
- Inventors: Zhiqiang Chen; Yuanjing Li; Li Zhang; Ziran Zhao; Jianping Gu; Shuo Wang
- Web page: https://patentgrep.com/patent/US10373701B2

## CPC

- G16B 5/00: ICT specially adapted for modelling or simulations in systems biology, e.g. gene-regulatory networks, protein interaction networks or metabolic networks
- G06F 17/18: for evaluating statistical data {, e.g. average values, frequency distributions, probability functions, regression analysis (forecasting specially adapted for a specific administrative, business or logistic context G06Q10/04)}
- G06T 17/20: Finite element generation, e.g. wire-frame surface description, {tesselation}
- G06V 10/7553: {based on shape, e.g. active shape models [ASM]}
- G06T 2210/41: Medical
- G06V 2201/033: of skeletal patterns
- G16B: BIOINFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR GENETIC OR PROTEIN-RELATED DATA PROCESSING IN COMPUTATIONAL MOLECULAR BIOLOGY
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING

## Abstract

Disclosed is method and apparatus for creating a statistical average model of an enamel-dentine junction. The method includes steps of acquiring CT image data of a tooth; segmenting the CT image data to obtain a surface of an enamel-dentine junction; segmenting the obtained surface using a curvature-based clustering algorithm to remove a bottom of the enamel-dentine junction; spherical-parameterizing, by means of spherical harmonic analysis, the surface of the enamel-dentine junction after removal of the bottom; and aligning different samples of the tooth to obtain a statistical average model.

## Claims

### Claim 1

A method of processing image data of a tooth for producing a physical tooth model that simulates structural and optical characteristics of the tooth, the method comprising:
acquiring, by a Computerized Tomography (CT) machine, CT image data of a tooth;
segmenting, by a computer, the CT image data to obtain a surface of an enamel-dentine junction of the tooth;
segmenting, by the computer, the obtained surface using a curvature-based clustering algorithm to remove a bottom of the enamel-dentine junction, wherein a triangular grid model is used to emulate the enamel-dentine junction, and wherein said curvature-based clustering algorithm comprises computing normal vectors at the vertices of the triangular grid model and computing curvatures at the vertices of the triangular grid model based on these normal vectors;
spherical-parameterizing, by the computer and by means of spherical harmonic analysis, the surface of the enamel-dentine junction after removal of the bottom; and
aligning, by the computer, different samples of the tooth to create a statistical average model of the enamel-dentine junction;
wherein the statistical average model of the enamel-dentine junction is used to produce the physical tooth model of the tooth, so that the tooth model simulates structural and optical characteristics of the tooth.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the CT image data are segmented using the Level Set algorithm.

### Claim 3 (depends on 2)

The method according to claim 2, wherein the clustering algorithm comprises the K-Means algorithm.

### Claim 4 (depends on 3)

The method according to claim 3, wherein the spherical-parameterization is performed using an optimized Control of Area and Length Distortions algorithm.

### Claim 5 (depends on 4)

The method according to claim 4, wherein the Control of Area and Length Distortions algorithm is optimized by adding weights.

### Claim 6 (depends on 1)

The method according to claim 1, further comprising:
applying spherical harmonics Fourier expansion on the parameterized surface after the spherical-parameterization.

### Claim 7 (depends on 6)

The method according to claim 6, wherein the alignment is performed in a spherical coordinate system.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the alignment is performed by means of the SPHARM Registration with Iterative Closest Point (SHREC) algorithm.

### Claim 9

An apparatus for processing image data of a tooth for producing a physical tooth model that simulates structural and optical characteristics of the tooth, the apparatus comprising:
a Computerized Tomography (CT) machine configured to acquire CT image data of a tooth;
a computer configured to create a statistical average model of an enamel-dentine junction of the tooth by
segmenting the CT image data to obtain a surface of the enamel-dentine junction;
segmenting the obtained surface using a curvature-based clustering algorithm to remove a bottom of the enamel-dentine junction, wherein a triangular grid model is used to emulate the enamel-dentine junction, and wherein said curvature-based clustering algorithm comprises computing normal vectors at the vertices of the triangular grid model and computing curvatures at the vertices of the triangular grid model based on these normal vectors;
spherical-parameterizing, by means of spherical harmonic analysis, the surface of the enamel-dentine junction after removal of the bottom; and
aligning different samples of the tooth to obtain the statistical average model;
wherein the statistical average model of the enamel-dentine junction is used to produce the physical tooth model of the tooth, so that the tooth model simulates structural and optical characteristics of the tooth based.