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Restoring the correct masticatory function of broken teeth is the basis of dental crown prosthesis rehabilitation. However, it is a challenging task primarily due to the complex and personalized morphology of the occlusal surface. In this article, we address this problem by designing a new two-stage generative adversarial network (GAN) to reconstruct a dental crown surface in the data-driven perspective. Specifically, in the first stage, a conditional GAN (CGAN) is designed to learn the inherent relationship between the defective tooth and the target crown, which can solve the problem of the occlusal relationship restoration. In the second stage, an improved CGAN is further devised by considering an occlusal groove parsing network (GroNet) and an occlusal fingerprint constraint to enforce the generator to enrich the functional characteristics of the occlusal surface. Experimental results demonstrate that the proposed framework significantly outperforms the state-of-the-art deep learning methods in functional occlusal surface reconstruction using a real-world patient database. Moreover, the standard deviation (SD) and root mean square (RMS) between the generated occlusal surface and the target crown calculated by our method are both less than 0.161 mm. Importantly, the designed dental crown have enough anatomical morphology and higher clinical applicability.

Restoring the normal masticatory function of broken teeth is a challenging task primarily due to the defect location and size of a patient's teeth. In recent years, although some representative image-to-image transformation methods (e.g. Pix2Pix) can be potentially applicable to restore the missing crown surface, most of them fail to generate dental inlay surface with realistic crown details (e.g. occlusal groove) that are critical to the restoration of defective teeth with varying shapes. In this article, we design a computer-aided Deep Adversarial-driven dental Inlay reStoration (DAIS) framework to automatically reconstruct a realistic surface for a defective tooth. Specifically, DAIS consists of a Wasserstein generative adversarial network (WGAN) with a specially designed loss measurement, and a new local-global discriminator mechanism. The local discriminator focuses on missing regions to ensure the local consistency of a generated occlusal surface, while the global discriminator aims at defective teeth and adjacent teeth to assess if it is coherent as a whole. Experimental results demonstrate that DAIS is highly efficient to deal with a large area of missing teeth in arbitrary shapes and generate realistic occlusal surface completion. Moreover, the designed watertight inlay prostheses have enough anatomical morphology, thus providing higher clinical applicability compared with more state-of-the-art methods.

PURPOSE To research and develop a novel virtual articulator system (the PN-300) based on computer binocular vision, raster scanning, and simulation technology and to conduct a preliminary evaluation of its accuracy. MATERIALS AND METHODS Two digital cameras were used to build the trajectory-tracking part of the virtual articulator system, and cameras combined with a projection module were used to form the scanning part of the system. The most prominent feature of the PN-300 is its ability to simultaneously obtain the 3D data of the subject's teeth and the movement trajectory of the mandible relative to the maxilla. The PN-300 recorded the linear, circular, and rectangular quadrilateral movements of a high-accuracy 3D electronic translation stage. The accuracy of measurement of the inclination of incisal guidance derived from the PN-300 based on the PROTAR evo7 articulator was also estimated. RESULTS The measurement error was below 100 μm for the linear and circular movements, and the angle error was within 0.2 degrees for the rectangular quadrilateral movements. The error of inclination of protrusive incisal guidance was 1.51 ± 0.68 degrees, and for incisal guidance was 0.82 ± 0.55 degrees. Trajectories and incisal 3D data obtained by the PN-300 were combined with data from plaster models and CBCT to simulate mandibular movement and to calculate the trajectories of the condyle. CONCLUSION The PN-300 achieved a good accuracy for recording mandibular movement and can be expected to calculate the movement of the condyle.

Purpose The purpose of this paper is to establish a chair-side design and production method for a tooth-supported fixed implant guide and to evaluate its accuracy. Design/methodology/approach Three-dimensional (3D) data of the alveolar ridge, adjacent teeth and antagonistic teeth were acquired from models of the edentulous area of 30 patients. The implant guides were then constructed using self-developed computer-aided design software and chair-side fused deposition modelling 3D-printing and positioned on a dental model. A model scanner was used to acquire 3D data of the positioned implant guides, and the overall error was then evaluated. Findings The overall error was 0.599 ± 0.146 mm (n = 30). One-way ANOVA revealed no statistical differences among the 30 implant guides. The gap between the occlusal surface of the teeth covering and the tissue surface of the implant guide was measured. The maximum gap after positioning of the implant guide was 0.341 mm (mean, 0.179 ± 0.019 mm). The implanted axes of the printed implant guide and designed guide were compared in terms of overall, lateral and angular error, which were 0.104 ± 0.004 mm, 0.097 ± 0.003 mm, and 2.053° ± 0.017°, respectively. Originality/value The results of this study demonstrated that the accuracy of a new chair-side tooth-supported fixed implant guide can satisfy clinical requirements.

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. Driving by the relative trajectory, a virtual dynamic occlusal adjustment system is developed to realize 3D occlusal movement simulating, automatic occluding relation detection, and automatic occlusal adjustment. Furthermore, we adapt an active occlusal adjustment method based on Laplacian deformation to increase the contact areas of the occlusal surface, which can aid dentists to realize the automatic adjustment of the non-interference regions. As a consequence, the proposed subtraction algorithm is feasible and the root-mean-square is 0.097 mm, and the adjusted occlusal surface is more consistent with the natural occlusal morphology. Graphical abstract ᅟ.

The aim of the study is to establish a virtual prediction method to predict aesthetic reconstruction effects in edentulous patients. The facial soft tissue surface data before and after wearing complete dentures of ten edentulous patients were acquired with a facial Three-dimension scanner. Then, the two sets of scanned data were entered into the same coordinate system. Manual interaction was performed to extract the external boundary of the perioral appearance deformation area, and the proportional relationships of key facial anatomical features were measured. A virtual prediction software module was developed based on back-propagation neural networks and a Laplacian deformation algorithm. Virtual prediction of the aesthetic reconstruction effects in the overall appearance of the lower third of the face was performed in 10 edentulous patients. The mean accuracy of the virtual predictions was approximately 0.769 ± 0.205 mm, and there were statistically significant differences between the 10 patients (p

Purpose: The aim of this study was to explore the application of computer-aided design and rapid prototyping (CAD/RP) for removable partial denture (RPD) frameworks and evaluate the fitness of the technique for clinical application. Materials and Methods: Three-dimensional (3D) images of dentition defects were obtained using a lab scanner. The RPD frameworks were designed using commercial dental software and manufactured using selective laser melting (SLM). A total of 15 cases of RPD prostheses were selected, wherein each patient received two types of RPD frameworks, prepared by CAD/RP and investment casting. Primary evaluation of the CAD/RP framework was performed by visual inspection. The gap between the occlusal rest and the relevant rest seat was then replaced using silicone, and the specimens were observed and measured. Paired t test was used to compare the average thickness and distributed thickness between the CAD/RP and investment casting frameworks. Analysis of variance test was used to compare the difference in thickness among different zones. Results: The RPD framework was designed and directly manufactured using the SLM technique. CAD/ RP frameworks may meet the clinical requirements with satisfactory retention and stability and no undesired rotation. Although the average gap between the occlusal rest and the corresponding rest seat of the CAD/RP frameworks was slightly larger than that of the investment casting frameworks (P < .05), it was acceptable for clinical application. Conclusion: RPD frameworks can be designed and fabricated directly using digital techniques with acceptable results in clinical application.

The tooth defect is a frequently occurring disease within the field of dental clinic. However, the traditional manual restoration for the defective tooth needs an especially long treatment time, and dental computer aided design and manufacture (CAD/CAM) systems fail to restore the personalized anatomical features of natural teeth. Aiming to address the shortcomings of existed methods, this article proposes an intelligent network model for designing tooth crown surface based on conditional generative adversarial networks. Then, the data set for training the network model is constructed via generating depth maps of 3D tooth models scanned by the intraoral. Through adversarial training, the network model is able to generate tooth occlusal surface under the constraint of the space occlusal relationship, the perceptual loss, and occlusal groove filter loss. Finally, we carry out the assessment experiments for the quality of the occlusal surface and the occlusal relationship with the opposing tooth. The experimental results demonstrate that our method can automatically reconstruct the personalized anatomical features on occlusal surface and shorten the treatment time while restoring the full functionality of the defective tooth.

This study evaluated the quality of impressions taken using three-dimensional (3D)-printed custom trays with different tissue stops to optimize the custom tray designs. Different custom trays were designed and printed based on six edentulous patients. These trays were divided into four groups based on the tissue-stop designs: 3DP trays (3D-printed trays without tissue stops), 3DPS trays (3D-printed trays with saddle-shaped tissue stops), 3DPM trays (3D-printed trays with marginal-band tissue stops) and 3DPIM trays (3D-printed trays with inner marginal-band tissue stops). Final impressions were taken using these trays, of which, the 3DP and 3DPIM trays were preborder-moulded. The finished complete dentures were used to take impressions that were set as the reference group to analyse the accuracy of the final impressions. The impressions taken using the 3DP custom trays (preborder-moulded) were used as a reference to analyse the extensions of the impressions taken using the other three custom trays. Randomized block or Friedman tests were used to evaluate each group’s statistical significance. The results revealed that the 3DPIM custom trays with the inner marginal-band tissue stop facilitated the preborder-moulding process and improved the accuracy and extension of the impression.

A dental defect is one of the most common oral diseases, and it often requires a full crown restoration. In this clinical operation, the dentist must manually prepare the affected tooth for the full crown so that it has a convergence angle between 4? and 10?, no undercuts, and uniform and even shoulder widths and depths using a high speed diamond bur in the patient's mouth within one hour, which is a difficult task that requires visual-manual operation. The quality of the tooth preparation has an important effect on the success rate of the subsequent prosthodontic treatment. This study involved research into digital modeling technology for full dental crown tooth preparation. First, the margin line of the tooth preparation was designed using a semi-automatic interactive process. Second, the inserting direction was automatically computed. Then, the characteristic parameters and the constraints on the tooth preparation were defined for the model. Next, the shoulder and axial surface of the tooth preparation were formed using parametric modeling. Finally, the implicit surface of a radial basis function was used to construct the tooth preparation's occlusal surface. The experimental results verified that the method of digital modeling for full crown preparation proposed in this study can quickly and accurately implement personalized designs of various parameters, such as the shoulder width and the convergence angle; it provides a digital design tool for full crown preparation. A new automatic digital modeling technology is proposed to design full dental crown tooth preparation.Margin line of the tooth preparation could be designed in advance.The implicit surface of a radial basis function was used to quickly and accurately construct the tooth preparation's occlusal surface.Our method can guarantee the design accuracy of the full crown tooth preparation (e.g. the shoulder width and the convergence).

Purpose To investigate a computer-aided design/computer-aided manufacturing (CAD/CAM) process for producing one-piece removable partial dentures (RPDs) and to evaluate their fits in vitro. Materials and methods A total of 15 one-piece RPDs were designed using dental CAD and reverse engineering software and then fabricated with polyetheretherketone (PEEK) using CAM. The gaps between RPDs and casts were measured and compared with traditional cast framework RPDs. Results Gaps were lower for one-piece PEEK RPDs compared to traditional RPDs. Conclusion One-piece RPDs can be manufactured by CAD/CAM, and their fits were better than those of traditional RPDs.

This study is to quantitatively evaluate the efficacy of using a non-contact automatic articulating paper dispenser for reducing microbial articulating paper contamination. Articulating papers in four-handed mode, non-four-handed mode, and via an automatic articulating paper dispenser were evaluated. An adenosine triphosphate bioluminescence assay was used to quantitatively measure the relative light unit (RLU) values of the rest unused articulating papers in the same package to detect contamination at 4 time points, and triplicate examinations were performed for all three methods. The RLUs were recorded, compared, and evaluated. For four-handed mode (n = 36), the RLUs at the four time points were 2.44, 32.89, 37.89, and 27.22, with a satisfactory rate of 94%. The RLUs for non-four-handed mode (n = 36) were 2.22, 286.44, 299.44, and 493.56, with a satisfactory rate of 36%. The RLUs for using the automatic dispenser (n = 36) were all 0 with a satisfactory rate of 100%. The satisfactory rates were significantly different among three methods. No significant differences were observed in the satisfactory rates for the four time points samples. Contact by gloved hands can cause severe biological contamination of articulating paper. However, by using standard four-handed mode or a non-contact automatic articulating paper dispenser, contamination can be controlled.

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. In this paper, we propose a new method of personalized teeth arrangement. Methods This paper presents a method of arranging teeth virtually for a complete denture. First, scan and extract the feature points of the 3D triangular mesh data of artificial teeth (PLY format), then establish a tooth selection system. Second, scan and mark the anatomic characteristics of the maxillary and mandibular cast surfaces, such as facial midline, the curve of the arches. With the enter information, the study calculates the common arrangement lines of artificial teeth. Third, select the preferred artificial teeth and automatically arrange them virtually in the correct position by using our own software. After that, design the gingival part of the dentures on the basic of the arranged teeth on the screen and then fabricated it by using Computerized Numerical Control (CNC) technology, Rapid Prototyping (RP) technology or 3D printer technology. Finally, select artificial teeth were embedded in wax rims. Results This system can choose artificial teeth reasonably and the teeth placement can meet the dentist's request to a certain extent, whereas all the operations are based on the medical principles. Conclusions The study performed here involves computer sciences, medicine, and dentistry, a teeth selection system was proposed and virtual teeth arrangement was described. This study has the capacity of helping operators to select teeth, which improved the accuracy of tooth arrangement, and customized complete denture.

Background Laser techniques have been introduced into dentistry to overcome the drawbacks of traditional treatment methods. The existing methods in dental clinical operations for tooth crown preparation have several drawbacks which affect the long-term success of the dental treatment. Objective To develop an improved robotic system to manipulate the laser beam to achieve safe and accurate three-dimensional (3D) tooth ablation, and thus to realize automatic tooth crown preparation in clinical operations. Method We present an automatic laser ablation system for tooth crown preparation in dental restorative operations. The system, combining robotics and laser technology, is developed to control the laser focus in three-dimensional motion aiming for high speed and accuracy crown preparation. The system consists of an end-effector, a real-time monitor and a tooth fixture. A layer-by-layer ablation method is developed to control the laser focus during the crown preparation. Experiments are carried out with picosecond laser on wax resin and teeth. Results The accuracy of the system is satisfying, achieving the average linear errors of 0.06 mm for wax resin and 0.05 mm for dentin. The angle errors are 4.33° for wax resin and 0.5° for dentin. The depth errors for wax resin and dentin are both within 0.1 mm. The ablation time is 1.5 hours for wax resin and 3.5 hours for dentin. Conclusions The ablation experimental results show that the movement range and the resolution of the robotic system can meet the requirements of typical dental operations for tooth crown preparation. Also, the errors of tooth shape and preparation angle are able to satisfy the requirements of clinical crown preparation. Although the experimental results illustrate the potential of using picosecond lasers for 3D tooth crown preparation, many research issues still need to be studied before the system can be applied to clinical operations. Lasers Surg. Med. 46:573–581, 2014. © 2014 Wiley Periodicals, Inc.

Background The existing methods in dental clinical operations for hard tissue removal have several drawbacks which affect the long-term success of the dental treatment. Methods In this paper, we introduce a miniature robotic device called LaserBot, which can manipulate a femtosecond laser beam to drill/burr a decayed tooth to realize clinical tooth crown preparation. In order to control the 3D motion of the laser focal point on the surface of a tooth, three miniature voice-coil motors with optical grating rulers are utilized to drive the 2D pitch/yaw rotation of a vibration mirror and 1D translation of a protruding optical lens. This method can provide high-resolution control of the laser beam. In order to maintain the small size of the robot, a parallel five linkage mechanism combined with a slider-rocker mechanism is developed to realize 2D pitch/yaw rotation of the vibration mirror. Results Experiment results show that the movement range and resolution of the laser beam point can meet the requirement of typical dental operations. The size of the working end of the device that enters the mouth is 25 × 22 × 57 mm (height × width × length), which is small enough to be mounted on any tooth. The average repeatability error of the laser focal point is about 40 µm. Ablation experiments on wax-resin material and on tooth validate that a femtosecond laser can be used for tooth ablation. Conclusions The developed robotic device achieved precise 3D motion control of a laser focal point and is small enough to be used in the narrow workspace of the oral cavity. Limitations of the prototype have been identified, and quantified specifications are identified for designing the next generation prototype. Copyright © 2014 John Wiley & Sons, Ltd.

Background: This paper introduces a method to digitally design a virtual model of a tooth preparation of the mandibular first molar, by using the commercial three-dimensional (3D) computer-aided design software packages Geomagic and Imageware, and using the model as an input to automatic tooth preparing system. Methods: The procedure included acquisition of 3D data from dentate casts and digital modeling of the shape of the tooth preparation components, such as the margin, occlusal surface, and axial surface. The completed model data were stored as stereolithography (STL) files, which were used in a tooth preparation system to help to plan the trajectory. Meanwhile, the required mathematical models in the design process were introduced. Results: The method was used to make an individualized tooth preparation of the mandibular first molar. The entire process took 15min. Discussion: Using the method presented, a straightforward 3D shape of a full crown can be obtained to meet clinical needs prior to tooth preparation.

This paper proposed a novel method for dental implant guide, based on computer aided design technique with CT data and dental 3D data. We analyze the patient's 3D dental data, and then plan the implant area and support area interactively. With the help of 2D image, we can accurately calculate the anatomical implants direction and a safe distance. With biomechanical principles as well as aesthetical and functional requirements as precondition, this method can make full use of the remaining teeth to ensure the support's stability. First of all, this method needs import and preprocess the model which needs repairing. Secondly, the implant direction was automatically computed. After that, the implant and support area was designed semi-automatically. Then, we design the dental platform and implant parametrically with the help of CT image registration. Finally, the dental implant guide is generated after Boolean operations. In the end of this paper, a case research explained the whole process of surgical guide. The results validated the correctness and feasibility of this method which has a great significance to enhance the quality and accuracy of implant surgery.

The article introduces a new method for three-dimensional reproduction of edentulous dental casts, and wax occlusion rims with jaw relation by using a commercial high-speed line laser scanner and reverse engineering software and evaluates the method's accuracy in vitro. The method comprises three main steps: (i) acquisition of the three-dimensional stereolithography data of maxillary and mandibular edentulous dental casts and wax occlusion rims; (ii) acquisition of the three-dimensional stereolithography data of jaw relations; and (iii) registration of these data with the reverse engineering software and completing reconstruction. To evaluate the accuracy of this method, dental casts and wax occlusion rims of 10 edentulous patients were used. The lengths of eight lines between common anatomic landmarks were measured directly on the casts and occlusion rims by using a vernier caliper and on the three-dimensional computerized images by using the software measurement tool. The direct data were considered as the true values. The paired-samples t-test was used for statistical analysis. The mean differences between the direct and the computerized measurements were mostly less than 0.04 mm and were not significant (P>0.05). Statistical significance among 10 patients was assessed using one-way analysis of variance (P

The aim of this study is to validate the feasibility and accuracy of a new automatic tooth preparation technique in dental healthcare. An automatic tooth preparation robotic device with three-dimensional motion planning software was developed, which controlled an ultra-short pulse laser (USPL) beam (wavelength 1,064 nm, pulse width 15 ps, output power 30 W and repeat frequency rate 100 kHz) to complete the tooth preparation process. A total of 15 freshly extracted human intact first molars were collected and fixed into a phantom head and the target preparation shapes of these molars were designed using customised computer-aided design (CAD) software. The accuracy of tooth preparation was evaluated using the Geomagic Studio and Imageware software and the preparing time of each tooth was recorded. Compared with the target preparation shape, the average shape error of the 15 prepared molars was 0.05–0.17 mm, the preparation depth error of the occlusal surface was approximately 0.097 mm and the error of the convergence angle was approximately 1.0°. The average preparation time was 17 minutes. These results validated the accuracy and feasibility of the automatic tooth preparation technique.

To explore G2G e-Government information sharing mode suitable to China’s national conditions and to boost the construction process of e-Government have already become hot spots among the management informationization strategies of Chinese government. First of all, an introduction of the current situation of China’s G2G e-Government information sharing is made. Secondly, the problems faced by G2G information sharing are analyzed. Based on cloud computing technology, an information sharing cloud applied to G2G e-Government area is put forward, a comparison between information sharing cloud mode and existing sharing mode is made, after that the TDABUM general framework model of information sharing cloud and its software architecture are designed, finally strategies of coconstruction and sharing of information sharing cloud are brought forward.

The conventional technique for the fabrication of complete dentures is complex, with a long fabrication process and difficult-to-control restoration quality. In recent years, digital complete denture design has become a research focus. Digital complete denture tooth arrangement is a challenging issue that is difficult to efficiently implement under the constraints of complex tooth arrangement rules and the patient's individualized functional aesthetics. The present study proposes a complete denture automatic tooth arrangement method driven by a reconfigurable rule; it uses four typical operators, including a position operator, a scaling operator, a posture operator, and a contact operator, to establish the constraint mapping association between the teeth and the constraint set of the individual patient. By using the process reorganization of different constraint operators, this method can flexibly implement different clinical tooth arrangement rules. When combined with a virtual occlusion algorithm based on progressive iterative Laplacian deformation, the proposed method can achieve automatic and individual tooth arrangement. Finally, the experimental results verify that the proposed method is flexible and efficient.

Background and Objective To develop a real-time recording system based on computer binocular vision and two-dimensional image feature extraction to accurately record mandibular movement in three dimensions. Methods A computer-based binocular vision device with two digital cameras was used in conjunction with a fixed head retention bracket to track occlusal movement. Software was developed for extracting target spatial coordinates in real time based on two-dimensional image feature recognition. A plaster model of a subject’s upper and lower dentition were made using conventional methods. A mandibular occlusal splint was made on the plaster model, and then the occlusal surface was removed. Temporal denture base resin was used to make a 3-cm handle extending outside the mouth connecting the anterior labial surface of the occlusal splint with a detection target with intersecting lines designed for spatial coordinate extraction. The subject's head was firmly fixed in place, and the occlusal splint was fully seated on the mandibular dentition. The subject was then asked to make various mouth movements while the mandibular movement target locus point set was recorded. Comparisons between the coordinate values and the actual values of the 30 intersections on the detection target were then analyzed using paired t-tests. Results The three-dimensional trajectory curve shapes of the mandibular movements were consistent with the respective subject movements. Mean XYZ coordinate values and paired t-test results were as follows: X axis: -0.0037 ± 0.02953, P = 0.502; Y axis: 0.0037 ± 0.05242, P = 0.704; and Z axis: 0.0007 ± 0.06040, P = 0.952. The t-test result showed that the coordinate values of the 30 cross points were considered statistically no significant. (P

Objectives: To quantitatively evaluate the correctness of a computer binocular vision mandibular 3D trajectory recording device. Methods: A specialized target shooting paper was neatly pasted on a high-precision three-axis electronic translation stage. A linear one-way movement was set at a speed of 1 mm/s along the X, Y, and Z directions for a distance of 10 mm each. The coordinates of 3 pre-set target points were recorded at the start and end by a computer binocular vision system with a frequency of 10 FPS and stored in TXT format. The TXT files were imported to Imageware 13.0, and the straight-line lengths between the start and end were measured. The mean difference between each length and 10 mm were calculated to evaluate the correctness of the distance measurement. The linear movement and recording procedure was repeated 3 times, but the speed was changed to 5 mm/s to simulate the human mandibular movement speed. The trajectories of the 3 target points were fitted and the vertical dimensions from each track point to the fitted lines were measured. The mean difference was calculated between the vertical dimensions and 0 mm to evaluate the correctness of recording trajectories using this device. Results: The correctness of distance measurements of the points 1, 2, and 3 were 0.06 mm, 0.16 mm, and 0.08 mm, respectively. The correctness of the trajectories of the points 1, 2, and 3 were 0.11 mm, 0.11 mm, and 0.10 mm, respectively. Conclusion: Using this computer binocular vision device, the correctness of the recorded linear trajectories in the range of 10 mm was better than 0.20 mm.

Objective: To evaluate the measurement accuracy of three-dimensional (3D) facial scanners for facial deformity patients from oral clinic. Methods: 10 patients in different types of facial deformity from oral clinical were included. Three 3D digital face models for each patient were obtained by three facial scanners separately (line laser scanner from Faro for reference, stereophotography scanner from 3dMD and structured light scanner from FaceScan for test). For each patient, registration based on Iterative Closest Point (ICP) algorithm was executed to align two test models (3dMD data & Facescan data) to the reference models (Faro data in high accuracy) respectively. The same boundaries on each pair models (one test and one reference models) were obtained by projection function in Geomagic Stuido 2012 software for trimming overlapping region, then 3D average measurement errors (3D errors) were calculated for each pair models also by the software. Paired t-test analysis was adopted to compare the 3D errors of two test facial scanners (10 data for each group). 3D profile measurement accuracy (3D accuracy) that is integrated embodied by average value and standard deviation of 10 patients’ 3D errors were obtained by surveying analysis for each test scanner finally. Results: 3D accuracies of 2 test facial scanners in this study for facial deformity were 0.44±0.08 mm and 0.43±0.05 mm. The result of structured light scanner was slightly better than stereophotography scanner. No statistical difference between them. Conclusions: Both test facial scanners could meet the accuracy requirement (0.5mm) of 3D facial data acquisition for oral clinic facial deformity patients in this study. Their practical measurement accuracies were all slightly lower than their nominal accuracies.

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. Firstly, to improve computational efficiency, the feature template is constructed to replace the deformed facial region. Secondly, a forecast model of elastic deformation is constructed using BP neural network and predicts elastic deformation amount because of the inhomogeneous, anisotropic and nonlinear material properties of soft tissue. Finally, a new feature template is calculated using deformation amount, and the deformation of preoperative model is simulated using Laplacian deformation technique. The average error rates of different hidden layer nodes in the neural network are analysed. Deformation and postoperative models are superimposed for match analysis. Experimental results show that this method can predict facial soft tissue deformation quickly and accurately. BP neural network is used to predict feature positions on facial model.The deformation of facial model is simulated using Laplacian deformation technique.This method can predict facial deformation quickly and accurately.CT scan is not necessary.

Objective. To quantitatively evaluate the tissue surface adaption of a maxillary complete denture wax pattern produced by CAD and 3DP.Methods. A standard edentulous maxilla plaster cast model was used, for which a wax pattern of complete denture was designed using CAD software developed in our previous study and printed using a 3D wax printer, while another wax pattern was manufactured by the traditional manual method. The cast model and the two wax patterns were scanned in the 3D scanner as “DataModel,” “DataWaxRP,” and “DataWaxManual.” After setting each wax pattern on the plaster cast, the whole model was scanned for registration. After registration, the deviations of tissue surface between “DataModel” and “DataWaxRP” and between “DataModel” and “DataWaxManual” were measured. The data was analyzed by pairedt-test.Results. For both wax patterns produced by the CAD&RP method and the manual method, scanning data of tissue surface and cast surface showed a good fit in the majority. No statistically significant (P>0.05) difference was observed between the CAD&RP method and the manual method.Conclusions. Wax pattern of maxillary complete denture produced by the CAD&3DP method is comparable with traditional manual method in the adaption to the edentulous cast model.

A removable complete denture is still the main selection for edentulous patients. Over the last five years, digital technologies for producing complete dentures have rapidly developed. Nevertheless, the design method for the baseplate has become the bottleneck of digital complete denture technology development. In this study, we report a novel method for the generation of aesthetic gingiva and polished surfaces of complete dentures that are driven by the feature curve, which can be conveniently modified using the gingival shape factor. A solid modeling method based on Poisson's surface reconstruction is used to generate a high-quality baseplate solid. This method can aid dentists to realize the rapid design process of personalized aesthetic baseplace. Finally, the experimental results verify that the method of digital design for the baseplate proposed is efficient and accurate (standard deviation < 0.01 mm).

The aim of this study was to explore a method for automatically reconstructing the occlusal surface by CAD technology. A 3D graphic database of standard tooth crown (STC) was established from physical models. Referring to the contact rule, the occlusal surface of STC was partitioned into several functional regions, and the regions related with occlusal adjustment were further defined as some sets of discrete points. Additionally, geometrical marks were added to the database to embody dimensional contours and orientation of STC. Then an adaptive redesign methodology was developed to form occlusal surface: firstly, a STC similar to patient's anatomical characteristics was scaled and registered to the abutment teeth; secondly, the distances between the point sets and the antagonist were calculated to quantify the occluding relation; finally, the occlusal surface was reconstructed by local deformation. The program provided a novel method to automatically adjust the size and location of the restoration, avoid interpenetrations and create necessary contacts. The final occlusal surface fulfills the esthetic and morphologic criteria in clinical dentistry and meets the physiologic demands of occlusal and proximal contacts.

This study explored a method for fabricating removable complete denture aided by CAD&RP technology. 3D crossing section scanner and laser scanner were respectively applied to obtain the surface data of artificial teeth, edentulous models and rims made in clinic. The vertical and horizontal relations of models were recorded before scanning with a special device. A 3D graphic database of artificial teeth, which can be aligned with parameters, was established. Special CAD software developed by ourselves was applied to the 3D integrated design process including automatic setting up artificial teeth, semiautomatic designing aesthetic and individualized artificial gingiva and base plate, automatic constructing individualized virtual flasks according to the finished CAD digital models of removable complete denture. At last, 3DP technology was used to make the individualized physical flasks. In this study, AMT and classic denture materials were effectually combined to achieve making removable complete denture aided by CAD/RP technology.