The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Oksam Chae - One of the best experts on this subject based on the ideXlab platform.
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VRCAI - A new visualization framework of dental CT images for Orthodontics
Proceedings of the 9th ACM SIGGRAPH Conference on Virtual-Reality Continuum and its Applications in Industry - VRCAI '10, 2010Co-Authors: Hui Gao, Jim X. Chen, Oksam ChaeAbstract:Dental CT images present complete information for tooth structures including both crown and root parts. 3D visualization of teeth from CT images provides important assistance for dentists performing Orthodontic Surgery and treatment. In the conventional visualization framework, volume rendering is applied for the tooth and skull visualization. The appearance of the rendered objects can be changed by adjusting the color transfer function and the opacity transfer function. Moreover, the marching cube method is applied to construct the 3D surface from the volume dataset. However, the constructed surface model takes the tooth and skull as a whole object. The individual tooth cannot be manipulated independently, which does not fit the requirement for the Orthodontic simulations. To this end, we propose a new visualization framework to render the skull and tooth independently. Several key modules are addressed including initialization, individual tooth segmentation, 3D visualization and 3D tooth manipulation. Experimental results on both fan beam CT and cone beam CT datasets show that the proposed method is efficient for the Orthodontic simulations.
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individual tooth segmentation from ct images using level set method with shape and intensity prior
Pattern Recognition, 2010Co-Authors: Oksam ChaeAbstract:3D visualization of teeth from CT images provides important assistance for dentists performing Orthodontic Surgery and treatment. However, dental CT images present several major challenges for the segmentation of tooth, which touches with adjacent teeth as well as surrounding periodontium and jaw bones. Moreover, tooth contour suffers from topological changes and splits into several branches. In this work, we focus on the segmentation of individual teeth with complete crown and root parts. To this end, we propose adaptive active contour tracking algorithms: single level set method tracking for root segmentation to handle the complex image conditions as well as the root branching problem, and coupled level set method tracking for crown segmentation in order to separate the touching teeth and create the virtual common boundaries between them. Furthermore, we improve the variational level set method in several aspects: gradient direction is introduced into the level set framework to prevent catching the surrounding object boundaries; in addition to the shape prior, intensity prior is introduced to provide adaptive shrinking or expanding forces in order to deal with the topological changes. The test results for both tooth segmentation and 3D reconstruction show that the proposed method can visualize individual teeth with high accuracy and efficiency.
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Improved B-spline contour fitting using genetic algorithm for the segmentation of dental computerized tomography image sequences
Journal of Imaging Science and Technology, 2007Co-Authors: Hui Gao, Hoon Heo, Oksam Chae, Jinsung Cho, Sungyoung Lee, Young-koo LeeAbstract:. In the dental field, 3D tooth modeling, in which each tooth can be manipulated individually, is an essential component of the simulation of Orthodontic Surgery and treatment. However, in dental computerized tomography slices teeth are located closely together or inside alveolar bone having an intensity similar to that of teeth. This makes it difficult to individually segment a tooth before building its 3D model. Conventional methods such as the global threshold and snake algorithms fail to accurately extract the boundary of each tooth. In this paper, we present an improved contour extraction algorithm based on B-spline contour fitting using genetic algorithm. We propose a new fitting function incorporating the gradient direction information on the fitting contour to prevent it from invading the areas of other teeth or alveolar bone. Furthermore, to speed up the convergence to the best solution we use a novel adaptive probability for crossover and mutation in the evolutionary program of the genetic algorithm. Segmentation results for real dental images demonstrate that our method can accurately determine the boundary for individual teeth as well as its 3D model while other methods fail. Independent manipulation of each tooth model demonstrates the practical usage of our method.
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Image Processing: Algorithms and Systems - Segmentation of tooth in CT images for the 3D reconstruction of teeth
electronic imaging, 2004Co-Authors: Hoon Heo, Oksam ChaeAbstract:In the dental field, the 3D tooth model in which each tooth can be manipulated individually is an essential component for the simulation of Orthodontic Surgery and treatment. To reconstruct such a tooth model from CT slices, we need to define the accurate boundary of each tooth from CT slices. However, the global threshold method, which is commonly used in most existing 3D reconstruction systems, is not effective for the tooth segmentation in the CT image. In tooth CT slices, some teeth touch with other teeth and some are located inside of alveolar bone whose intensity is similar to that of teeth. In this paper, we propose an image segmentation algorithm based on B-spline curve fitting to produce smooth tooth regions from such CT slices. The proposed algorithm prevents the malfitting problem of the B-spline algorithm by providing accurate initial tooth boundary for the fitting process. This paper proposes an optimal threshold scheme using the intensity and shape information passed by previous slice for the initial boundary generation and an efficient B-spline fitting method based on genetic algorithm. The test result shows that the proposed method detects contour of the individual tooth successfully and can produce a smooth and accurate 3D tooth model for the simulation of Orthodontic Surgery and treatment.
Taís Barbosa - One of the best experts on this subject based on the ideXlab platform.
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Occlusal, chewing, and tasting characteristics associated with orofacial dysfunctions in children with unilateral cleft lip and palate: a case-control study
Clinical Oral Investigations, 2018Co-Authors: Ana Bheatriz Marangoni Montes, Thais Marchini Oliveira, Maria Beatriz Duarte Gavião, Taís BarbosaAbstract:Objective The objective of this study is to assess the associations between orofacial dysfunctions with malocclusion, masticatory performance, and taste in children with and without unilateral cleft lip and palate (UCLP). Material and methods A patient-based, matched, case-control study was conducted involving 108 8- to 10-year-old children divided in UCLP and control groups. Orofacial dysfunctions were evaluated using the Nordic Orofacial Test-Screening (NOT-S). Orthodontic treatment need was evaluated using the Goslon Yardstick Index (GYI) and the Index of Orthodontic Treatment Need (IOTN) of patients and controls, respectively. Masticatory performance was assessed using a chewable test material to determine median particle size ( X _50) and distribution of particles in different sieves ( b value). Taste perception was evaluated using four solutions (sweet, salty, bitter, or acid) in three different concentrations. Results More than half of the patients needed Orthodontic Surgery. UCLP group presented higher median particle size and needed more chewing cycles to comminute the artificial test into particles smaller than the median than those of controls. UCLP group had less perception of salty flavor than controls. There was a positive correlation between b value and NOT-S examination score for patients. In regression analysis, a significant interrelationship was observed between NOT-S examination score and b value. Conclusions In the UCLP patients, masticatory performance was compromised probably as a result of facial asymmetry and speech disturbance; whereas, taste was less perceived only for salty flavor. Clinical relevance These findings provide preliminary evidence that mastication and taste are altered in children with UCLP, so these factors must be followed up to ensure oral and general health in growing individuals.
Ana Bheatriz Marangoni Montes - One of the best experts on this subject based on the ideXlab platform.
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Occlusal, chewing, and tasting characteristics associated with orofacial dysfunctions in children with unilateral cleft lip and palate: a case-control study
Clinical Oral Investigations, 2018Co-Authors: Ana Bheatriz Marangoni Montes, Thais Marchini Oliveira, Maria Beatriz Duarte Gavião, Taís BarbosaAbstract:Objective The objective of this study is to assess the associations between orofacial dysfunctions with malocclusion, masticatory performance, and taste in children with and without unilateral cleft lip and palate (UCLP). Material and methods A patient-based, matched, case-control study was conducted involving 108 8- to 10-year-old children divided in UCLP and control groups. Orofacial dysfunctions were evaluated using the Nordic Orofacial Test-Screening (NOT-S). Orthodontic treatment need was evaluated using the Goslon Yardstick Index (GYI) and the Index of Orthodontic Treatment Need (IOTN) of patients and controls, respectively. Masticatory performance was assessed using a chewable test material to determine median particle size ( X _50) and distribution of particles in different sieves ( b value). Taste perception was evaluated using four solutions (sweet, salty, bitter, or acid) in three different concentrations. Results More than half of the patients needed Orthodontic Surgery. UCLP group presented higher median particle size and needed more chewing cycles to comminute the artificial test into particles smaller than the median than those of controls. UCLP group had less perception of salty flavor than controls. There was a positive correlation between b value and NOT-S examination score for patients. In regression analysis, a significant interrelationship was observed between NOT-S examination score and b value. Conclusions In the UCLP patients, masticatory performance was compromised probably as a result of facial asymmetry and speech disturbance; whereas, taste was less perceived only for salty flavor. Clinical relevance These findings provide preliminary evidence that mastication and taste are altered in children with UCLP, so these factors must be followed up to ensure oral and general health in growing individuals.
Xiaoping Yuan - One of the best experts on this subject based on the ideXlab platform.
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Stability of the anterior teeth and hard tissue of skeletal class III malocclusion after Orthodontic Surgery: systematic review
West China journal of stomatology, 2015Co-Authors: Mengxuan Deng, Xiaoping YuanAbstract:OBJECTIVE This study aims to analyze the long-term stability of the anterior teeth and hard tissue of skeletal class III malocclusion after a three-year Orthodontic Surgery by systematic review. METHODS All studies about skeletal class III malocclusion with Orthodontic-Surgery were searched by computer-based retrieval and manual retrieval; the deadline is December 2013. The literature, filtered according to the inclusion criteria and exclusion criteria, was performed with quality. assessment. The same indicators of the anterior location and hard tissue stability were combined and evaluated with metaanalysis and descriptive analysis by Rev Man5.2. RESULTS Four before-and-after comparison study articles with 180 cases were included. The grades of the four literature evaluation were A. The meta-analysis results showed that comparing the three-year post-Orthodontic-Surgery and post-Orthodontic-Surgery, the total weighted mean difference (WMD) of Ul-SN was 4.29 (P 0.05). The measurement methods of A and B point position were different, hence the qualitative description were as follows: point A remained at a relatively stable position, and point B had some replacement compared with post-operative (P
Thais Marchini Oliveira - One of the best experts on this subject based on the ideXlab platform.
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Occlusal, chewing, and tasting characteristics associated with orofacial dysfunctions in children with unilateral cleft lip and palate: a case-control study
Clinical Oral Investigations, 2018Co-Authors: Ana Bheatriz Marangoni Montes, Thais Marchini Oliveira, Maria Beatriz Duarte Gavião, Taís BarbosaAbstract:Objective The objective of this study is to assess the associations between orofacial dysfunctions with malocclusion, masticatory performance, and taste in children with and without unilateral cleft lip and palate (UCLP). Material and methods A patient-based, matched, case-control study was conducted involving 108 8- to 10-year-old children divided in UCLP and control groups. Orofacial dysfunctions were evaluated using the Nordic Orofacial Test-Screening (NOT-S). Orthodontic treatment need was evaluated using the Goslon Yardstick Index (GYI) and the Index of Orthodontic Treatment Need (IOTN) of patients and controls, respectively. Masticatory performance was assessed using a chewable test material to determine median particle size ( X _50) and distribution of particles in different sieves ( b value). Taste perception was evaluated using four solutions (sweet, salty, bitter, or acid) in three different concentrations. Results More than half of the patients needed Orthodontic Surgery. UCLP group presented higher median particle size and needed more chewing cycles to comminute the artificial test into particles smaller than the median than those of controls. UCLP group had less perception of salty flavor than controls. There was a positive correlation between b value and NOT-S examination score for patients. In regression analysis, a significant interrelationship was observed between NOT-S examination score and b value. Conclusions In the UCLP patients, masticatory performance was compromised probably as a result of facial asymmetry and speech disturbance; whereas, taste was less perceived only for salty flavor. Clinical relevance These findings provide preliminary evidence that mastication and taste are altered in children with UCLP, so these factors must be followed up to ensure oral and general health in growing individuals.