Ki-Heon Lee

Chonnam National University, Gwangju, Gwangju, South Korea

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Publications (11)12.88 Total impact

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    ABSTRACT: To develop a hard coating for stainless surfaces based on silver (Ag)-platinum (Pt) alloys. Ag-Pt alloys, which have high degree of biocompatibility, excellent resistance to sterilization conditions, and antibacterial properties to different bacteria, are associated with long-term antibacterial efficiency. Approximately 1.03-µm to 2.34-µm-thick coatings, as determined by scanning electron microscopy, were deposited on stainless surfaces by the simultaneous vaporization of both metals (Ag and Pt) in an inert argon atmosphere. The coating was done by physical vapor deposition. Microorganisms and eukaryotic culture cells were grown on these surfaces. The coatings released sufficient Ag ions when immersed in phosphate-buffered saline and showed significant antimicrobial potency against Streptococcus mutans and Aggregatibacter actinomycetemcomitans strains. At the same time, human gingival fibroblast cells were not adversely affected. Ag-Pt coatings on load-bearing orthodontic bracket surfaces can provide suitable antimicrobial activity during active orthodontic treatment.
    Full-text · Article · Aug 2011 · The Angle Orthodontist
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    ABSTRACT: Objective: To investigate whether the accuracy of 3D laser scanning is influenced by the angles and number of scans. Methods: Using a 3D laser scanner, 10 manikins with facial markers were scanned at 7 horizontal angles (front view and at 20°, 45°, and 60° angles on the right and left sides). Three-dimensional facial images were reconstructed by 6 methods differing in the number and angles of scans, and measurements of these images were compared to the physical measurements from the manikins. Results: The laser scan images were magnified by 0.14 - 0.26%. For images reconstructed by merging 2 scans, excluding the front view; and by merging 3 scans, including the front view and scans obtained at 20° on both sides; several measurements were significantly different than the physical measurements. However, for images reconstructed by merging 3 scans, including the front view; and 5 scans, including the front view and scans obtained at 20° and 60° on both sides; only 1 measurement was significantly different. Conclusions: These results suggest that the number and angle of scans influence the accuracy of 3D laser scanning. A minimum of 3 scans, including the front view and scans obtained at more than 45° on both sides, should be integrated to obtain accurate 3D facial images. (Korean J Orthod 2011;41(2):76-86).
    Full-text · Article · Apr 2011 · The Korean Journal of Orthodontics
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    ABSTRACT: The purpose of this study was to investigate various factors associated with initial miniscrew stability for the prediction of the success rate. A total of 378 miniscrews in 154 patients were examined by reviewing their charts. Potential confounding variables examined were age, sex, jaw (maxilla or mandible), placement site, tissue mobility (firm or movable tissue), type, length, and diameter of the miniscrew, and the number of previous operations. The outcome variable of this study was initial stability, defined as the stability of the miniscrew from placement to orthodontic force application. We used the generalized estimating equations method to estimate the influence of each factor on stability for the correlated outcomes of each patient. The overall success rate was 83.6% for all miniscrews (316 of 378). After adjusting for the type of miniscrew, the relative success rate in the mandible was 0.48 times that in the maxilla but without statistical significance (crude odds ratio = 0.52, P = 0.13; adjusted odds ratio = 0.48, P = 0.09). There was no statistically significant association of any factors in this model with respect to initial stability. These results suggest that initial stability cannot be guaranteed or predicted. For this reason, any treatment plan should consider the possibility of failure.
    Full-text · Article · Sep 2009 · American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics
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    ABSTRACT: Purpose: This study was to evaluate the validity of superimposition range at facial images constructed with 3-dimensional (3D) surface laser scanning system. Materials and methods: For the present study, thirty adults, who had no severe skeletal discrepancy, were selected and scanned twice by a 3D laser scanner (VIVID 910, Minolta, Tokyo, Japan) with 12 markers placed on the face. Then, two 3D facial images (T1-baseline, T2-30 minutes later) were reconstructed respectably and superimposed in several manners with (Inus, Seoul, Korea) software program. The distances between markers at the same place of face were measured in superimposed 3D facial images and measurement were done all the 12 makers respectably. Results: The average linear distances between the markers at the same place in the superimposed image constructed by upper 2/3 of the face was , in the superimposed image constructed by upper 1/2 of the face was , in the superimposed image constructed by upper 1/3 of the face and nose area was , in the superimposed image constructed by upper 1/3 of the face was , and in the superimposed image constructed by whole face was . There were no statistically significant differences in the liner distances of the makers placed on the area included in superimposition range used for partial registration methods but there were significant differences in the linear distances of the markers placed on the areas not included in superimposition range between whole registration method and partial registration methods used in this study. Conclusion: The results of the present study suggest that the validity of superimposition is decreased as superimposition range is reduced in the superimposition of 3D images constructed with 3D laser scanner for the same subject.
    Full-text · Article · Jan 2009
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    ABSTRACT: Objective: The purpose of this study was to examine the effect of ipriflavone on periodontal reorganization and prevention of relapse following tooth movement. Methods: Orthodontic rubber bands were inserted between the first and second maxillary molars of 27 white male rats for 3 weeks for experimental tooth movement. From one day before the removal of orthodontic rubber band, ipriflavone was administered 50 or 400 mg/kg daily in each experimental group whereas carboxymethyl cellulose solution was administered in the control group. They were sacrificed at the 5, 10, and 15th day from the day of removal of orthodontic rubber bands. The amount of relapse was evaluated by measuring the interdental space, and the extent of periodontal reorganization was compared through histological examination. Results: In case of ipriflavone administration, the amount and velocity of relapse was less and slower compared to the control group. In addition, the ipriflavone group showed more rapid periodontal reorganization compared to the control group. Conclusions: The results of the present study suggest that ipriflavone administration can be used effectively in the prevention of relapse following orthodontic tooth movement through the acceleration of periodontal reorganization. (Korean J Orthod 2008;38(5):347-357)
    Full-text · Article · Oct 2008 · The Korean Journal of Orthodontics
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    ABSTRACT: Objective: The purpose of this study was to evaluate the reproducibility of measurements representing asymmetry of the mandible and to identify which landmarks would be more useful in 3-dimensional (3D) CT imaging. Methods: Facial CT images were obtained from forty normal occlusion individuals. Eighteen landmarks were established from the condyle, gonion, and menton areas, and 25 measurements were constructed to represent asymmetry of the mandible; 8 for ramus length, 12 for mandibular body length, 1 for condylar neck length, 2 for frontal ramal inclination, and 2 for lateral ramal inclination. Inter- and intra-examiner reproducibility of the measurements was evaluated. Resutts: Inter-examiner reproducibility of the measurements proved to be high except for 3 measurements. Intra-examiner reproducibility also proved to be high except for 2 measurements. Inter- and intra-examiner reproducibility of the measurements including Gonion proved to be low. Conclusions: The results of the present study indicate that the landmarks and measurements constructed in 3D CT images can be used for the diagnosis of facial asymmetry. (Korean J Orthod 2008;38(5):314-327)
    Full-text · Article · Oct 2008 · The Korean Journal of Orthodontics
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    ABSTRACT: The purposes of this study were to classify patients with facial asymmetry by using the cluster analysis and to evaluate the characteristics of the resultant groups. One hundred consecutive orthodontic patients who had frontal cephalograms and photographs taken for the diagnosis of facial asymmetry were included in the sample. A cluster analysis was used to classify the subjects, with craniofacial measurements related to asymmetry obtained from the cephalograms and photographs. The subjects were divided into 5 clusters based on only 3 variables from the frontal cephalograms: menton deviation, apical base midline discrepancy, and vertical difference of right and left antegonion. The results of the ANOVA test according to the variables showed statistically significant differences between the groups in all variables, indicating that each group can be easily identified with the variables. The results suggest that patients with facial asymmetry can be classified simply based on some variables on frontal cephalograms, and this classification can be helpful in proper diagnosis and treatment planning for these patients.
    Full-text · Article · Oct 2007 · American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics
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    ABSTRACT: The purpose of this study was to investigate factors affecting lip-line canting by using musculoskeletal analyses. Fifty-six adults with lip-line canting were selected as subjects. They were divided into 3 groups according to the changes of lip line during smiling: increasing (group I), decreasing (group D), and minimal (group M). Lip-line canting at rest was correlated to craniofacial morphology and muscular activity: Regarding craniofacial morphology, various craniofacial measurements in lateral and frontal cephalograms were used, including inclination of the tongue blade placed across both first molars. The zygomaticus major was the focus of the measurement of muscular activity affecting lip-line canting, and its activity during smiling was evaluated by using a needle electrode. In group I, lip-line canting at rest showed a significant correlation with the right-left (R/L) difference of muscular activity, but no significant correlation with the measurements of craniofacial morphology. In group D, lip-line canting showed a positive correlation with the measurements of craniofacial morphology, such as the inclination of the tongue blade, and a negative correlation with the R/L difference of muscular activity. In group M, lip-line canting showed no significant correlation with the R/L difference of muscular activity, but a significant correlation with inclination of the tongue blade. The results indicate that lip-line canting is caused by craniofacial morphology when the change of lip-line canting during smiling is minimal, whereas lip-line canting is affected by the R/L difference of muscular activity in addition to craniofacial morphology when the cant of lip line markedly changes during smiling. The findings suggest that the cause of lip-line canting can be identified easily by the change of canting during smiling, without complicated musculoskeletal analyses.
    Full-text · Article · Oct 2007 · American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics
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    ABSTRACT: In this study, we evaluated errors introduced into the interpretation of facial asymmetry on posteroanterior (PA) cephalograms due to malpositioning of the x-ray emitter focal spot. We tested the hypothesis that horizontal displacements of the emitter from its ideal position would produce systematic displacements of skull landmarks that could be fully accounted for by the rules of projective geometry alone. A representative dry skull with 22 metal markers was used to generate a series of PA images from different emitter positions by using a fully calibrated stereo cephalometer. Empirical measurements of the resulting cephalograms were compared with mathematical predictions based solely on geometric rules. The empirical measurements matched the mathematical predictions within the limits of measurement error (x= 0.23 mm), thus supporting the hypothesis. Based upon this finding, we generated a completely symmetrical mathematical skull and calculated the expected errors for focal spots of several different magnitudes. Quantitative data were computed for focal spot displacements of different magnitudes. Misalignment of the x-ray emitter focal spot introduces systematic errors into the interpretation of facial asymmetry on PA cephalograms. For misalignments of less than 20 mm, the effect is small in individual cases. However, misalignments as small as 10 mm can introduce spurious statistical findings of significant asymmetry when mean values for large groups of PA images are evaluated.
    Full-text · Article · Aug 2007 · American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics
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    ABSTRACT: To test the antiadherent and antibacterial properties of surface modification of orthodontic wires with photocatalytic titanium oxide (TiO(2)). TiO(2) was coated on the surface of the orthodontic wires by a sol-gel thin film dip-coating method. Bacterial adhesion to the wires was evaluated by the weight change of the wires. The antibacterial activity of the surface-modified orthodontic wires was demonstrated by the dilution agar plate method for Streptococcus mutans and spectrophotometry for Porphyromonas gingivalis. The orthodontic wires coated with the photocatalytic TiO(2) showed an antiadherent effect against S. mutans compared with the uncoated wires. The bacterial mass that bound to the TiO(2)-coated orthodontic wires remained unchanged, whereas that of the uncoated wires increased by 4.97%. Furthermore, the TiO(2)-coated orthodontic wires had a bactericidal effect on S. mutans and P. gingivalis, which cause dental caries and periodontitis, respectively. The antiadherent and antibacterial mechanisms of TiO(2) to break down the cell wall of those bacteria were revealed by scanning electron microscopy. The surface modification of orthodontic wires with photocatalytic TiO(2) can be used to prevent the development of dental plaque during orthodontic treatment.
    Full-text · Article · Jun 2007 · The Angle Orthodontist
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    ABSTRACT: The advent of computed tomography has greatly reduced magnification errors from geometric distortions that are common in conventional radiographs. Recently introduced 3-dimensional (3D) software enables 3D reconstruction and quantitative measurement of the maxillofacial complex; 3D images are also useful in understanding asymmetrical structures. This article describes the use of 3D images in the diagnosis of facial asymmetry. A step-by-step procedure for 3D analysis developed by the authors is described by using the example of a 23-year-old man with a chin deviation to 1 side.
    Full-text · Article · Jan 2007 · American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics