The braid index of DNA double crossover polyhedral links.

In this paper, the authors study the mathematical properties of a class of alternating links called polyhedral links which have been used to model DNA polyhedra. The motivation of such studies is to provide guidance and aid in the research of the properties of certain DNA molecules. For example, such studies can provide characterizations of the structural complexity of DNA molecules.

Facial morphology prediction after complete denture restoration based on principal component analysis.

In developing treatment plan before complete denture restoration, doctors need to help the patient regain chewing ability while considering facial shape reconstruction after the surgery. At present, facial deformation prediction depends on the subjective judgment and experience of doctors; thus, an accurate basis for scientific quantitative analysis is lacking. With the development of computer technology, this paper proposed new facial morphology prediction method based on principal component analysis.

Relative trajectory-driven virtual dynamic occlusal adjustment for dental restorations.

The abnormal occlusal contact can disrupt the coordination and health of the oral jaw system. Therefore, the dynamic adjustment of the occlusal surface is of great significance for assessing the status of occlusal contact and clarifying jaw factors of stomatognathic system diseases. To solve this problem, a trajectory subtraction algorithm based on screw theory to improve the accuracy of the occlusal movement trajectory is proposed in our paper.

Study on digital teeth selection and virtual teeth arrangement for complete denture.

Background And Objective: In dentistry, the complete denture is a conventional treatment for edentulous patients. The computer-aided design and computer-aided manufacturing (CAD/CAM) has been applied on the digital complete denture which is developed rapidly. Tooth selection and arrangement is one of the most important parts in digital complete denture.

Deformation of facial model for complete denture prosthesis using ARAP group method and elastic properties.

With the development of 3D printing and computer graphics technology, mouth rehabilitation has increasingly adopted digital methods. This research proposes a new method to transform the appearance of facial model after complete denture prosthesis. A feature template with few feature points is first constructed according to the facial muscle anatomy and facial deformation after complete denture prosthesis.

Robust tooth surface reconstruction by iterative deformation.

Digital design technologies have been applied extensively in dental medicine, especially in the field of dental restoration. The all-ceramic crown is an important restoration type of dental CAD systems. This paper presents a robust tooth surface reconstruction algorithm for all-ceramic crown design.

Automatic segmentation in image stacks based on multi-constraint level-set evolution.

Contour extraction of image stacks is a basic task in medical modeling. The existing level-set methods usually suffer from some problems (e.g.

Prediction of facial deformation after complete denture prosthesis using BP neural network.

With the accelerated aging of world population, complete denture prosthesis plays an increasingly important role in mouth rehabilitation. In addition to recovering stomatognathic system function, restoring the appearance of a third of the area under the face has become a great challenge in complete denture prosthesis. This study analyzes the interactive relationship between the appearance of a third of the area under the face and complete denture, and proposes a new method to predict facial deformation after complete denture prosthesis.

Personalized Orthodontic Accurate Tooth Arrangement System with Complete Teeth Model.

The accuracy, validity and lack of relation information between dental root and jaw in tooth arrangement are key problems in tooth arrangement technology. This paper aims to describe a newly developed virtual, personalized and accurate tooth arrangement system based on complete information about dental root and skull. Firstly, a feature constraint database of a 3D teeth model is established.

Ear decomposition of 3-regular polyhedral links with applications.

In this paper, we introduce a notion of ear decomposition of 3-regular polyhedral links based on the ear decomposition of the 3-regular polyhedral graphs. As a result, we obtain an upper bound for the braid index of 3-regular polyhedral links. Our results may be used to characterize and analyze the structure and complexity of protein polyhedra and entanglement in biopolymers.

The braid index of complicated DNA polyhedral links.

The goal of this paper is to determine the braid index of two types of complicated DNA polyhedral links introduced by chemists and biologists in recent years. We shall study it in a more broad context and actually consider so-called Jaeger's links (more general Traldi's links) which contain, as special cases, both four types of simple polyhedral links whose braid indexes have been determined and the above two types of complicated DNA polyhedral links. Denote by b(L) and c(L) the braid index and crossing number of an oriented link L, respectively.

Single-Tooth Modeling for 3D Dental Model.

An integrated single-tooth modeling scheme is proposed for the 3D dental model acquired by optical digitizers. The cores of the modeling scheme are fusion regions extraction, single tooth shape restoration, and single tooth separation. According to the "valley" shape-like characters of the fusion regions between two adjoining teeth, the regions of the 3D dental model are analyzed and classified based on the minimum curvatures of the surface.

[Computer aided design and manufacture of the removable partial denture framework].

This paper demonstrates the successful application of a novel approach to the computer aided design (CAD) of removable partial denture (RPD) framework. Firstly, we get the data of the partially edentulous cast, a mandibular Kennedy Class II, through a 3D-optical grating measuring system after corresponding pretreatment. Then, the reverse engineering software and 3D CAD software was used to design basis, big conjunction, clasp, small conjunction of the RPD framework.

[Establishment of database with standard 3D tooth crowns based on 3DS MAX].

The database with standard 3D tooth crowns has laid the groundwork for dental CAD/CAM system. In this paper, we design the standard tooth crowns in 3DS MAX 9.0 and create a database with these models successfully.

[Computer aided design and manufacture of the porcelain fused to metal crown].

In order to satisfy the current demand for fast and high-quality prosthodontics, we have carried out a research in the fabrication process of the porcelain fused to metal crown on molar with CAD/CAM technology. Firstly, we get the data of the surface mesh on preparation teeth through a 3D-optical grating measuring system. Then, we reconstruct the 3D-model crown with the computer-aided design software which was developed by ourselves.

[Research and application of computer-aided technology in restoration of maxillary defect].

This paper presents a new method of designing restoration model of maxillectomy defect through Computer aided technology. Firstly, 3D maxillectomy triangle mesh model is constructed from Helical CT data. Secondly, the triangle mesh model is transformed into initial computer-aided design (CAD) model of maxillectomy through reverse engineering software.

[Virtual orientation of the lower and upper jaws model on the position of centric occlusion].

The rotation axis equation of the simple articulator is built by the cylinder feature identification, which facilitates the rotation transform of the lower jaw data. Then the collision points and areas on the position of centric occlusion are found to form two collision couples. The virtual orientation of the lower and upper jaws model is realized by collision detection of the collision couples.

[The development of a system for 3D reconstruction from DICOM data and collaborative visualization].

Complex surgeries often need multi-disciplinary surgeons to work collaboratively and set synthesized operation plans. Aided by collaboration enabled three dimensional visualization software over network, operation plans can be made more intuitively and accurately. Because different disciplinary surgeons often work at different locations, a distributed collaboration virtue environment over network should be provided.

[Research and implement of the primary motion simulation based on virtual articulator].

This paper presents our work on the research process of virtual articulator simulation. Firstly, plaster models of upper jaw and low jaw are measured by 3D-optical measuring system and processed to get the available data. Secondly, complex physical modeling of the jaw motion is simplified and decomposed to a series of position transform, such as translation, rotation, etc.