• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.138-145
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• 2009

Custom medical treatment is being widely adapted to lots of medical applications. A technology for 3D modeling is strongly required to fabricate medical implants for individual patient. Needs on true 3D CAD data of a patient is strongly required for tissue engineering and human body simulations. Medical imaging devices show human inner section and 3D volume rendering images of human organs. CT or MRI is one of the popular imaging devices for that use. However, those image data is not sufficient to use for medical fabrication or simulation. This paper mainly deals how to generate 3D geometry data from those medical images. A new image processing technology is introduced to reconstruct 3D geometry of a human body vacancy from the medical images. Then a surface geometry data is reconstructed by using Marching cube algorithm. Resulting CAD data is a custom 3D geometry data of human vacancy. This paper introduces a novel 3D reconstruction process and shows some typical examples with implemented software.

• Journal of Powder Materials
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• v.20 no.6
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• pp.467-473
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• 2013

This research presents a preparation method of dental components by metal injection molding process (MIM process) using titanium scrap. About $20{\mu}m$ sized spherical titanium powders for MIM process were successfully prepared by a novel dehydrogenation and spheroidization method using in-situ radio frequency thermal plasma treatment. The effects of MIM process parameters on the mechanical and biological properties of dental components were investigated and the optimum condition was obtained. After sintering at $1250^{\circ}C$ for 1 hour in vacuum, the hardness and the tensile strength of MIMed titanium components were 289 Hv and 584 MPa, respectively. Prepared titanium dental components were not cytotoxic and they showed a good cell proliferation property.

• Clinics in Shoulder and Elbow
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• v.9 no.1
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• pp.34-41
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• 2006

Purpose: This study is to analyze the result and complications of internal fixation with T-plate for two-part fracture of the neck of the humerus. Materials and Methods: The clinical results of fourteen patients who had been performed with this method mentioned above were reviewed. Their average age was 49.6. Postoperative mean follow up period was 24.1 months. Radiological evaluation was done by Kronberg's and shoulder function by Neer's. Results: By Kronberg evaluation, nine cases were good, two cases acceptable and three cases poor. By Neer's, mean score of shoulder function was 77.6 and 4 cases were excellent, one satisfactory, five unsatisfactory and four failure. The complications were the sfiff shoulder, loss of reduction and avascular necrosis of humeral head. Conclusion: In this study, there were differences according to the age. And we obtained an unsatisfactory result in patients over 50 years old. We consider that in patients over 50 years old, the differences were due to the muscle weakness through wide surgical approaches, postoperative implant loosening or the stiffness caused by poor rehabilitation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.23-23
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• 2018

In this study, new titanium alloys were prepared by adding elements such as tantalum (Ta), zirconium (Zr) and the like to complement the biological, chemical and mechanical properties of titanium alloys. The Ti-40Ta-xZr ternary alloy was formed on the basis of Ti-40Ta alloy with the contents of Zr in the contents of 0, 3, 7 and 15 wt. %. Plasma electrolytic oxidation (PEO), which combines high-voltage sparks and electrochemical oxidation, is a novel method to form ceramic coatings on light metals such as Ti and its alloys. These oxide film produced by the electrochemical surface treatment is a thick and uniform porous form. It is also composed of hydroxyapatite and calcium phosphate-based phases, so it has the characteristics of bone inorganic, non-toxic and very high bioactivity and biocompatibility. Ti-40Ta-xZr alloys were homogenized in an Ar atmosphere at $1050^{\circ}C$ for 1 hour and then quenched in ice water. The electrochemical oxide film was applied by using a power supply of 280 V for 3 minutes in 0.15 M calcium acetate monohydrate ($Ca(CH_3COO)_2{\cdot}H_2O$) and 0.02 M calcium glycerophosphate ($C_3H_7CaO_6P$) electrolyte. A small amount of 0.0075M zinc acetate and magnesium acetate were added to the electrolyte to enhance the bioactivity. The mechanical properties of the coated surface of Ti-40Ta-xZr alloys were evaluated by Vickers hardness, roughness test, and elastic modulus using nano-indentation, and the surface wettability was evaluated by measuring the contact angle of the coated surface. In addition, cell activation and differentiation were examined by cell culture of HEK 293 (Human embryonic kidney 293) cell proliferation. Surface properties of the alloys were analyzed by scanning electron microscopy(FE-SEM), EDS, and X-ray diffraction analysis (XRD).

• Journal of Sensor Science and Technology
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• v.20 no.1
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• pp.19-24
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• 2011

Brain disorders such as epilepsy is a condition that affects an estimated 2.7 million Americans, 50,000,000 worldwide, approximately 200,000 new cases of epilepsy are diagnosed each year. Of the major chronic medical conditions, epilepsy is among the least understood. Scientists are conducting research to determine appropriate treatments, such as the use of drugs, vagus nerve stimulation, brain stimulation, and Peltier chip-based focal cooling. However, brain stimulation and Peltier chip-based stimulation processes cannot effectively stop seizures. This paper presents simulation of a novel heat enchanger network(HEN) technique designed to stop seizures by using a neural cooling probe to stop focal and spontaneous seizures by cooling the brain. The designed probe was composed of a U-shaped tube through which cold fluid flowed in order to reduce the temperature of the brain. The simulation results demonstrated that the neural probe could cool a 7 $mm^2$ area of the brain when the fluid was flowing atb a velocity of 0.55 m/s. It also showed that the neural cooling probe required 23 % less energy to produce cooling when compared to the Peltier chip-based cooling system.

• Journal of Periodontal and Implant Science
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• v.28 no.1
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• pp.57-70
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• 1998

The purpose of this study was to evaluate the clinical and microbiological effects of metronidazole 25% dental gel that was applied to periodontal pockets who have moderate to advanced chronic adult periodontitis were selected for this study. The quadrants that had 2 or 3teeth with 5-8mm probing pocket depth were selected and divided into test side and control side according to the split-mouth design. The metronidazole 25% dental gel applied on test side and 0.12% chlorhexidine solution applicated on positive control side, normal saline irrigation into periodontal pocket was applicated to negative control side respectively. Above procedures followed scaling and root planing at baseline(0week). The subgingival sterile saline irrigation and chlorhexidine irrigation were done for about 30 seconds respectively. The metronidazole 25% dental gel was applied to periodontal pocket at 0,1 week in the test side. The clinical and microbiological analysis carried out at baseline(0week) and 4,8 weeks. The results of this study were as follows; 1. The sulcular bleeding index, probing pocket depth were significantly reduced in the test group. The relative proportions of spirochetes and motile rods were significantly reduced to negative control group and the proportion of cocci was correspondingly increased in the test group. 2. The sulcular bleeding index, probing pocket depth were significantly reduced in metronidazole group. and, there was a significant differences between 2 groups. Also, the relative proportions of spirochetes and motile rods were reduced in both group. And, there was a significant differences between 2 groups. In conclusion, application of metronidazole 25% dental gel as an adjunct to mechanical debridement of root surfaces may improved the clinical and microbiological status of periodontal disease sites.

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.179-189
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• 1997

Teeth mobility is an important part of a periodontal examination, because it represents a function of the persisting height of the alveolar bone and the width of the periodontal ligament. The purpose of this study was to evaluate clinical difference in teeth mobility after treatment with the modified Widman flap and the undisplaced flap in humans. Twenty males with moderate periodontal disease were selected. The severity of periodontal disease was evaluated with sulcular bleeding index, pocket depth and attachment level and tooth mobility was measured with Periotest(Siemens Co., Germany) at the initial examination, 1, 2, 4, 6, 8 and 12 weeks following the modified Widman flap and the undisplaced flap operation using the split-mouth technique. The relation of mobility to clinical parameters was statistically analyzed by multiple regression and the change of teeth mobility according to healing process by independent t-test using SPSS program. The results were as follows: 1. There was a strong relationship between the Periotest value(PTV) and attachment level. 2. The change of teeth mobility in both flap procedures was increased significantly at 1 week post-op. and was decreased to preoperative level at 4 weeks post-op, in modified Widman flap and at 6 weeks post-op. in undisplaced flap. 3. The change of teeth mobility in premolar teeth group in undisplaced flap compared to modified Widman flap was generally increased but these changes were not statistically significant. The changes of teeth mobility in molar teeth group in undisplaced flap was increased significantly at 2 weeks post-op.. 4. The change of teeth mobility following undisplaced flap was increased significantly compared to that of modified Widman flap at 2 weeks post-op.

• Journal of Periodontal and Implant Science
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• v.24 no.1
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• pp.165-177
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• 1994

To investigate the depth of the root concavity and root surface area of the maxillary first premolar, 40 maxillary first premolars were used. All the teeth which extracted because of advanced periodontal disease and orthodontic treatment procedure, were sectioned every 1.5mm from cementoenameljunction to the apex with hard tissue microtome. Each sectioned root was taken photograph with slide film, and projected for measuring with a calibrated digital Curvi-Meter. The root surface area, percentage of the RSA and the linear variation of the RSA were calibrated for each 1.5mm section. Linear variation of the depth of root concavity was measured on mesial and distal root surface for each section using computer-aided digitizer. The results were as follows. 1. The total mean root length of maxillary first premolar was 13.48mm. Mean buccal root length of 2-rooted tooth was 12.59mm, mean palatal root length was 12.73mm, and mean root length of single rooted tooth was 13.78mm. 2. The total mean root surface area of maxillary first premolar was $194.17mm^2$, mean root surface area for 2-rooted tooth was $205.97mm^2$ and mean root surface area for single rooted tooth was $188.49mm^2$. 3. It was 59.93% of the total root surface area that the area from CEJ to coronal 6mm. And, the coronal half of the root length accounted for approximately 71.76% of the total root surface area. 4. Most deepest concavity of the mesial root surface was 0.65mm at apical 3.0mm, 4.5mm level in maxillary first premolar. And, that of the distal root surface was 0.37mm at apical 4.5mm level. 5. All of the maxillary first premolar had mesial root surface concavity. This mesial root surface concavity appeared to be more pronounced in 2-rooted tooth than single rooted tooth.

• The Journal of Advanced Prosthodontics
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• v.8 no.4
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• pp.321-328
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• 2016

PURPOSE. This study was designed to investigate the maintenance of teeth and implants in patients with viral liver disease. MATERIALS AND METHODS. 316 patients without any significant systemic disease were selected as a control group. Liver disease group was consisted of 230 patients. Necessary data were collected using clinical records and panoramic radiographs. Then, the patients were subdivided into 2 groups based on the type of active dental therapy received before maintenance period (Pre-Tx). Analysis for finding statistically significant difference was performed based on the need for re-treatment of active dental therapy (Re-Tx) and change in the number of teeth (N-teeth) and implants (N-implants). RESULTS. Comparing to control group, the patients with liver disease showed higher value on N-teeth, N-implants, and Re-Tx. Statistically significant differences were found on N-teeth (P=.000) and Re-Tx (P=.000) in patients with non-surgical Pre-Tx. Analysis based on severity of liver disease showed that N-teeth and Re-Tx were directly related to severity of liver disease regardless of received type of Pre-Tx. Significant differences were found on N-teeth (P=.003) and Re-Tx (P=.044) in patients with non-surgical Pre-Tx. CONCLUSION. In this study, it was concluded that liver disease might influence the loss of teeth and cause the relapse of dental disease during maintenance period in patients. A significant positive relationship between tooth and implant loss and severity of liver disease seems to exist.

• Journal of Periodontal and Implant Science
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• v.44 no.6
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• pp.280-287
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• 2014

Purpose: The purpose of this randomized single-blind controlled trial was to elucidate the clinical and antimicrobial effects of daily phototherapy (PT) as an adjunct to scaling and root planing (SRP) in patients with chronic periodontitis. Methods: The study was conducted from December 2013 to May 2014 at Ewha Womans University Mokdong Hospital, Seoul, Korea. Forty-one patients with mild to moderate chronic periodontitis were randomly divided into two therapeutic groups in a 1:1 ratio: SRP+PT and SRP (control) groups. All participants underwent full-mouth SRP. PT was performed thrice a day for a month by using electric toothbrushes with embedded light-emitting diodes. Plaque index, gingival index, probing pocket depth (PPD), clinical attachment level (CAL), and bleeding on probing were assessed before (baseline) and four weeks after (follow-up) the treatment. Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia, Fusobacterium nucleatum, Parvimonas micra, Campylobacter rectus, Eikenella corrodens, Streptococcus mutans, and Streptococcus sobrinus levels were detected by a real-time polymerase chain reaction at the same points in time. Results: The clinical parameters improved in both the groups. At the follow-up assessment, PPD was significantly decreased in the SRP+PT group (P=0.00). Further, PPD and CAL showed significantly greater changes in the SRP+PT group than in the SRP group (PPD, P=0.03; CAL, P=0.04). P. gingivalis and T. forsythia levels decreased in this group, but no significant intergroup differences were noted. Conclusions: Adjunctive PT seems to have clinical benefits, but evidence of its antimicrobial effects is not sufficient. Long-term studies are necessary to develop the most effective PT protocol and compare the effectiveness of PT with and without exogenous photosensitizers.