• The korean journal of orthodontics
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• v.52 no.2
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• pp.85-101
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• 2022

Objective: To classify facial asymmetry (FA) phenotypes in adult patients with skeletal Class III (C-III) malocclusion. Methods: A total of 120 C-III patients who underwent orthognathic surgery (OGS) and whose three-dimensional computed tomography images were taken one month prior to OGS were evaluated. Thirty hard tissue landmarks were identified. After measurement of 22 variables, including cant (°, mm), shift (mm), and yaw (°) of the maxilla, maxillary dentition (Max-dent), mandibular dentition, mandible, and mandibular border (Man-border) and differences in the frontal ramus angle (FRA, °) and ramus height (RH, mm), K-means cluster analysis was conducted using three variables (cant in the Max-dent [mm] and shift [mm] and yaw [°] in the Manborder). Statistical analyses were conducted to characterize the differences in the FA variables among the clusters. Results: The FA phenotypes were classified into five types: 1) non-asymmetry type (35.8%); 2) maxillary-cant type (14.2%; severe cant of the Max-dent, mild shift of the Man-border); 3) mandibular-shift and yaw type (16.7%; moderate shift and yaw of the Man-border, mild RH-difference); 4) complex type (9.2%; severe cant of the Max-dent, moderate cant, severe shift, and severe yaw of the Man-border, moderate differences in FRA and RH); and 5) maxillary reverse-cant type (24.2%; reverse-cant of the Max-dent). Strategic decompensation by pre-surgical orthodontic treatment and considerations for OGS planning were proposed according to the FA phenotypes. Conclusions: This FA phenotype classification may be an effective tool for differential diagnosis and surgical planning for Class III patients with FA.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.10
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• pp.48-58
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• 1998

We present a method that can recognize face images using independent component analysis that is used mainly for blind sources separation in signal processing. We assumed that a face image can be expressed as the sum of a set of statistically independent feature images, which was obtained by using independent component analysis. Face recognition was peformed by projecting the input image to the feature image space and then by comparing its projection components with those of stored reference images. We carried out face recognition experiments with a database that consists of various varied face images (total 400 varied facial images collected from 10 per person) and compared the performance of our method with that of the eigenface method based on principal component analysis. The presented method gave better results of recognition rate than the eigenface method did, and showed robustness to the random noise added in the input facial images.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.12 no.3
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• pp.250-255
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• 2012

Face recognition has wide applications in security and surveillance systems as well as in robot vision and machine interfaces. Conventional challenges in face recognition include pose, illumination, and expression, and face recognition at a distance involves additional challenges because long-distance images are often degraded due to poor focusing and motion blurring. This study investigates the effectiveness of applying photon-counting linear discriminant analysis (Pc-LDA) to face recognition in harsh environments. A related technique, Fisher linear discriminant analysis, has been found to be optimal, but it often suffers from the singularity problem because the number of available training images is generally much smaller than the number of pixels. Pc-LDA, on the other hand, realizes the Fisher criterion in high-dimensional space without any dimensionality reduction. Therefore, it provides more invariant solutions to image recognition under distortion and degradation. Two decision rules are employed: one is based on Euclidean distance; the other, on normalized correlation. In the experiments, the asymptotic equivalence of the photon-counting method to the Fisher method is verified with simulated data. Degraded facial images are employed to demonstrate the robustness of the photon-counting classifier in harsh environments. Four types of blurring point spread functions are applied to the test images in order to simulate long-distance acquisition. The results are compared with those of conventional Eigen face and Fisher face methods. The results indicate that Pc-LDA is better than conventional facial recognition techniques.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.2
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• pp.184-199
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• 1996

The challenges to achieve three dimensional facial proportionality and occusal stability in many patients with complex dentofacial deformity have been met by the development and use of the maxilla, mandible, and chin surgery techniques in combination with efficient orthodontic treatment. There is a clinical, biological, and biomechanical foundation for simultaneous surgical repositioning of the maxilla, mandible, and chin in a significant proportion of adult and adolescent patients. A combination of the surgical and orthodontic approach may provide increased treatment efficiencies and optimal esthetic results. Art and science to determine the treatment objectives, specifically, the desired soft tissue changes are firstly established by using the clinician's "esthetic sense" of the facial beauty and proportion aided to a few cephalometric guidelines. In this sense, the dependence on the clinician's "esthetic eye" by Dr. Bell is more important in analyzing the facial proportion than the satisfaction of rigid cephalometric norms. The purpose of this article was to elucidate the indication for simultaneous surgical repositioning of the maxilla, mandible, and chin, and to describe the clinical cephalometric analysis for orthognathic surgery. Representative 6 case reports were presented and discussed to illustrate the esthetic, orthodontic, and surgical treatment objectives with long-term follow-up.

• The korean journal of orthodontics
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• v.4 no.1
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• pp.21-29
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• 1974

The purpose of the present study is to evaluate changes of the soft tissue relative to underlying skeletal elements during orthodontic treatment, and the influence of orthodontic treatment quantitatively on various regions of the facial profile. 59 Korean young women were selected, whose Hellman dental age was IV A, IV C and V A. Lateral cephalometric head films were taken before and after orthodontic treatment. From tracings, landmarks on skeletal and soft tissue profile were located, and then their linear and angular measurements were made directly. The results were obtained as follow: 1) Soft tissues of the facial profile were closely related and dependent on the underlying dentoskeletal frameworks. Orthodontic treament resulted in the reduction of dentofacial protrusion with both upper and lower lips becoming less procumbent during treament. 2) Thickness of the upper lip increased considerably during orthodontic treatment, and this change was related to maxillary incisor retraction. The ratio between the amount of maxillary incisor retraction and that of increment of upper lip thickness was approximately 5:3. 3) Soft tissue thickness overlying Downs' point A, point B and pogonion was not modified by orthodontic treatment. 4) Holdaway's H line, relating facial profile to the underlying dentoskeletal framework, seemed to be the most practical approach to soft tissue analysis.

• The korean journal of orthodontics
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• v.48 no.5
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• pp.333-338
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• 2018

Objective: The aim of this study was to compare the buccolingual inclination of maxillary and mandibular molars in adults with different vertical facial types. Methods: Cone-beam computed tomography images of 135 adult patients (age, 20-45 years) with skeletal Class I maxillomandibular relationships were assigned to normodivergent (n = 46), hypodivergent (n = 49), and hyperdivergent groups (n = 40) according to linear and angular sella-nasion/gonion-menton measurements. The normodivergent group consisted of 24 females and 22 males, hypodivergent group of 26 females and 23 males, and hyperdivergent group of 24 females and 16 males. Buccolingual inclination of the maxillary and mandibular first and second molars was measured relative to the occlusal plane. One-way analysis of variance was used for intergroup comparison. Gender differences were evaluated using independent t-tests. Results: Buccolingual molar inclinations did not differ significantly between females and males (p > 0.05). There were no statistically significant differences among the buccolingual inclinations of the first and second maxillary and mandibular molars of the groups (p > 0.05). Conclusions: Buccolingual inclinations of maxillary and mandibular molars are similar in normodivergent, hyperdivergent, and hypodivergent adults with Class I sagittal relationships.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.424-437
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• 2003

This study was observed the variations in skin color, hydration, sebum content according to age groups at the forehead, both cheeks, and chin in 154 healthy Korean women subjects with aged 30 to 59. We selected four face sites (forehead, right cheek, left cheek, and chin) and measured with chromameter, corneometer, and sebumeter. All statistical analysis was performed on the computer software package SPSS 8.0. There was no significant difference of lightness between facial four regions in age groups but lightness showed to tend to age-related decrease on each regions. Redness and yellowness showed the highest values on chin and forehead respectively but there was no tendency to steady changes according to age variation. Both cheeks showed the highest hydration level and the lowest sebum content compared with forehead and chin in all age groups and there was tendency to age-related changes of sebum content on both cheeks. So we concluded there was decreasing tendency in lightness and sebum content according to the increase of age and there was no age-related change of skin hydration level at least in facial skin.(omitted)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.5
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• pp.777-782
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• 2002

This study will offer multimodal recognition instead of an existing monomodal bioinfomatics by using facial multi-feature to improve the accuracy of recognition and to consider the convenience of user . Each bioinfomatics vector can be found by the following ways. For a face, the feature is calculated by principal component analysis with wavelet multiresolution. For a lip, a filter is used to find out an equation to calculate the edges of the lips first. Then by using a thinning image and least square method, an equation factor can be drawn. A feature found out the facial parameter distance ratio. We've sorted backpropagation neural network and experimented with the inputs used above. Based on the experimental results we discuss the advantage and efficiency.

• Imaging Science in Dentistry
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• v.49 no.1
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• pp.35-43
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• 2019

Purpose: The goal of this study was to assess the accuracy and reliability of a low-cost portable scanner (Scanify) for imaging facial casts compared to a previously validated portable digital stereophotogrammetry device (Vectra H1). This in vitro study was performed using 2 facial casts obtained by recording impressions of the authors, at King's College London Academic Centre of Reconstructive Science. Materials and Methods: The casts were marked with anthropometric landmarks, then digitised using Scanify and Vectra H1. Computed tomography (CT) scans of the same casts were performed to verify the validation of Vectra H1. The 3-dimensional (3D) images acquired with each device were compared using linear measurements and 3D surface analysis software. Results: Overall, 91% of the linear Scanify measurements were within 1 mm of the corresponding reference values. The mean overall surface difference between the Scanify and Vectra images was <0.3mm. Significant differences were detected in depth measurements. Merging multiple Scanify images produced significantly greater registration error. Conclusion: Scanify is a very low-cost device that could have clinical applications for facial imaging if imaging errors could be corrected by a future software update or hardware revision.

• Korean Journal of Head & Neck Oncology
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• v.39 no.2
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• pp.35-39
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• 2023

Solitary fibrous tumor (SFT), which was initially believed to be a subtype of mesothelioma, has been reported to occur outside the pleura. In the head and neck region, it primarily manifests in the oral or nasal cavity, with rare occurrences in the facial region. A 40-year-old woman visited our hospital with a mass on her chin. Prior to surgery, involuntary movement was observed in the ipsilateral corner of the mouth upon palpation of the mass. Special care was taken during the surgical procedure to avoid damaging the facial nerve. The mass was excised, and histological examination and immunohistochemical analysis confirmed the diagnosis of an SFT. Here, we present the first reported case of an SFT diagnosed in a jaw mass in Korea. The objective of this study was to highlight the importance of the diagnostic accuracy of SFTs in lower jaw masses.