• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.512-519
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• 2007

The purpose of this study is to investigate the potential of a novel tissue engineering approach to regenerate intervertebral disc. In this study, thermosensitive scaffold (chitosan-Pluronic hydrogel) and nanofiber were used to replace the nucleus pulposus (NP) and annulus fibrosus of a degenerated intervertebral disc, leading to an eventual regeneration of the disc using the minimally invasive surgical procedure and organ culture. In preliminary study, disc cells were seeded into the scaffolds and cellular responses were assessed by MTT assay and scanning electron microscopy (SEM). Based on these results, we could know that tissue engineered scaffolds might provide favorable environments for the regeneration of tissues. Organ culture was performed in fresh porcine spinal motion segments with endplates on both sides. These spinal motion segments were classified into three groups: control (Intact), injured NP (Defect), and inserting tissue engineered scaffolds (Insert). The specimens were cultivated for 7 days, subsequently structural stability, cell proliferation and morphological changes were evaluated by the relaxation time, quantity of DNA, GAG and histological examination. In these results, inserting group showed higher relaxation time, reduced decrement of DNA contents, and accumulated GAG amount. Consequently, the tissue engineered scaffolds used in this study seen to be a promising base scaffolds for regenerative intervertebral disc due to its capacity to absorb external dynamic loading and the possible ideal environment provided for disc cell growing.

• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.499-506
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• 2008

The purpose of this study was to compare the push-out strength of a fiber post cemented with various resin cements. Newly extracted 36 human mandibular premolars which had single root canal were selected and their crown portions were removed. The root canal was instrumented using $PROTAPER^{TM}$ system and obturated using continuous wave technique. In each root, a 9-mm deep post space was prepared. #2 translucent fiber post (DT Light post, Bisco Inc., Schaumburg, IL, U.S.A.) was cemented using injection technique with Uni-dose needle tip (Bisco) and six different resin cements. The tested resin cements were Duo-Link (Bisco Inc., Schaumburg, IL, U.S.A.), Variolink II (Ivoclar-Vivadent AG, Schann, Liechtenstein), Panavia F (Kuraray Medical Inc., Okayama, Japan), Multilink Automix (Ivoclar-Vivadent AG, Schann, Liechtenstein), RelyX Unicem (3M ESPE Dental Products, St. Paul, MN, U.S.A.), and Maxcem (Kerr Co., CA, U.S.A.). After storage in distilled water for 24 hours, each root was transversally sectioned into approximately 1-mm thick sections. This procedure resulted in 6 serial sections per root. Push-out test wasperformed using a universal testing machine (EZ Test, Shimadzu Co.) with a crosshead speed of 1 mm/min. The data were analyzed with one-way ANOVA and Tukey HSD (p=0.05). The push-out strength of the groups which cemented fiber post with Panavia F and Multilink Automix were lower than those of the other groups. But, there were no statistically significant difference among groups at a probability level of 0.05.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.4
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• pp.301-307
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• 2004

The flap considered at first for the reconstruction of large maxillary defect, especially mid-face defect, is scapular free flap, because it provides ample composite tissue which can be designed 3-dimensionally for orbital, facial and oral reconstruction. In case of maxillary defect involving hard palate, however, this flap has some limitations. First, its bulk prevents oral function and physio-anatomic reconstruction of nasal and oral cavity. Second, mobility and thickness of cutaneous paddle covering the alveolar area reduce retention of tissue-supported denture and give rise to peri-implantitis when implant is installed. Third, lateral border of scapula that is to reconstruct maxillary arch and hold implants is straight, not U-shaped maxillary arch form. To overcome these problems, new concept of step prefabrication technique was provided to a 27-year-old male patient who had been suffering from a complete hard palate and maxillary alveolar ridge defect. In the first stage, scapular osteomuscular flap was elevated, tailored to fit the maxillary defect, particulated autologous bone was placed subperiosteally to simulate U-shaped alveolar process, and then wrapped up with split thickness skin graft(STSG, 0.3mm thickness). Two months later, thus prefabricated new flap was elevated and microtransferred to the palato-maxillary defect. After 6 months, 10 implant fixtures were installed along the reconstructed maxillary alveolus, with following final prosthetic rehabilitation. The procedure was very successful and patient is enjoying normal rigid diet and speech.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.534-547
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• 2006

Ectopic eruption and impaction of canines is a frequently encountered clinical problems. The incidence of impaction ranges between 1-3%. The cause of canine impaction can be the result of localized factors or can be a polygenic multifactorial inheritance and associated with other dental anomalies. The general dentist and pediatric dentist should know how to properly diagnose and manage potential disturbances in the eruption of maxillary canine. Diagnosis of impacted canine at age 8-10 years can significantly reduce serious ramifications, including surgical exposure and orthodontic traction as well as root resorption of the lateral incisors. Extraction of primary canine would be one of the method to prevent the impaction. The surgical procedure should be designed to minimize the destruction of periodontal tissue of impacted canine. Closed eruption technique is thought to be optimal method of surgical exposure compared with other methods. An overview of the incidence, sequela as well as the surgical periodontal, and orthodontic consideration in the management of impacted canine was presented.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.77-77
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• 2017

Titanium and its alloys offer attractive properties in a variety of applications. These are widely used for the field of biomedical implants because of its good biocompatibility and high corrosion resistance. Titanium anodizing is often used in the metal finishing of products, especially those can be used in the medical devices with dense oxide surface. Based on SAE/AMS (Society of Automotive Engineers/Aerospace Material Specification) 2488D, it has the specification for industrial titanium anodizing that have three different types of titanium anodization as following: Type I is used as a coating for elevated temperature forming; Type II is used as an anti-galling coating without additional lubrication or as a pre-treatment for improving adherence of film lubricants; Type III is used as a treatment to produce a spectrum of surface colours on titanium. In this study, we have focused on Type II anodization for the medical (dental and orthopedic) application, the anodized surface was modified with gray color under alkaline electrolyte. The surface characteristics were analyzed with Focused Ion Beam (FIB), Scanning Electron Microscopy (SEM), surface roughness, Vickers hardness, three point bending test, biocompatibility, and corrosion (potentiodynamic) test. The Ti-6Al-4V alloy was used for specimen, the anodizing procedure was conducted in alkaline solution (NaOH based, pH>13). Applied voltage was range between 20 V to 40 V until the ampere to be zero. As results, the surface characteristics of anodic oxide layer were analyzed with SEM, the dissecting layer was fabricated with FIB method prior to analyze surface. The surface roughness was measured by arithmetic mean deviation of the roughness profile (Ra). The Vickers hardness was obtained with Vickers hardness tester, indentation was repeated for 5 times on each sample, and the three point bending property was verified by yield load values. In order to determine the corrosion resistance for the corrosion rate, the potentiodynamic test was performed for each specimen. The biological safety assessment was analyzed by cytotoxic and pyrogen test. Through FIB feature of anodic surfaces, the thickness of oxide layer was 1.1 um. The surface roughness, Vickers hardness, bending yield, and corrosion resistance of the anodized specimen were shown higher value than those of non-treated specimen. Also we could verify that there was no significant issues from cytotoxicity and pyrogen test.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.543-547
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• 2016

Acute stroke is a one of common disease that require fast diagnosis and treatment to save patients life. however, the acute stroke may cause lifelong disability due to brain damage with no prompt surgical procedure. In order to diagnose the Stroke, brain perfusion CT examination and possible rapid implementation of 3D angiography has been widely used. However, a low-dose technique should be applied for the examination since a lot of radiation exposure to the patient may cause secondary damage for the patients. Therefore, the degradation of the measured CT images may interferes with a clinical check in that blood vessel shapes on the CT image are significantly affected by gaussian noise. In this study, we employed the spatio-temporal technique to analyze dynamic (brain perfusion) CT data to improve an image quality for successful clinical diagnosis. As a results, proposed technique could remove gaussian noise successfully, demonstrated a possibility of new image segmentation technique for CT angiography. Qualitative evaluation was conducted by skilled radiological technologists, indicated significant quality improvement of dynamic CT images. the proposed technique will be useful tools as a clinical application for brain perfusion CT examination.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.671-683
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• 2005

Statement of problem: The most commonly reported problem associated with dental implant restoration is the loosening of the screws. Purpose: This study compared the efficacy of an implant system incorporating an anti-rotational locking sleeve(Anti-Rotating Inner Post Screw System(ARIPS-system)) with other, traditional implant systems as a means of minimizing vibration loosening. Materials and methods: Three implant systems were examined; the conventional external hex type, the ARIPS-system, and the internal taper type implant system 30 specimens(10 samples per group)were fabricated and each abutment screw was secured to the implant future with 32Ncm of torque force and loosening torque was measured using a Torque Gauge. The procedure was repeated 3 times, recording initial loosening torque each time. The re-tightened abutment screw was subjected to a cyclic load having a maximum forte of 200N and minimum of 20N at 2Hz over a period of 12,600 cycles. after which the loosening torque was measured. Measured values were calaulated for statistical analysis. Analysis of measured value was performed by 3 methods: (i) as a percentage average of the initial 3 loosening-torque values(initial loosening value) to the tightening torque of 32Ncm, (ii) as a percentage of the loosening torque value after a load of 200N(experimental value) to the initial loosening value, and (iii) as a percentage of the experimental value to the 32Ncm of tightening torque. The analyses shows the amount of initial loosening at the screw, loosening by repetitive load and the the final loosening value. Results: The results of this study were as follows (1) Percentage of initial loosening value to tightening-torque was increased in order of external hex, ARIPS-system and internal taper and all values between each groups showed statistical significance (p<0.05). (2) Percentage of experimental value to initial loosening value was increased in order of external hex, ARIPS-system and internal taper. Value of internal taper showed significant difference with those of external hex and ARIPS-system (p<0.05). (3) Percentage of experimental value to tightening torque was increased in order of external hex, ARIPS-system and internal taper and all values between each groups showed statistical significance (p<0.05). Conclusion: The results of the analysis of the final loosening level value, which are closely correlated to clinical use, show that the ARIPS-system can be a useful means of minimizing abutment screw loosening when compared to the external hex type system. Although further clinical studies need to be made, the ARIPS-system should be considered to maximize the long-term success of the implant prosthesis.

• The Korean Journal of Pain
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• v.27 no.3
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• pp.278-284
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• 2014

Background: Establishment of laparoscopic cholecystectomy as an outpatient procedure has accentuated the clinical importance of reducing early postoperative pain, as well as postoperative nausea and vomiting (PONV). We therefore planned to evaluate the role of a multimodal approach in attenuating these problems. Methods: One hundred and twenty adult patients of ASA physical status I and II and undergoing elective laparoscopic cholecystectomy were included in this prospective, randomized, placebo-controlled study. Patients were divided into four groups of 30 each to receive methylprednisolone 125 mg intravenously or etoricoxib 120 mg orally or a combination of methylprednisolone 125 mg intravenously and etoricoxib 120 mg orally or a placebo 1 hr prior to surgery. Patients were observed for postoperative pain, fentanyl consumption, PONV, fatigue and sedation, and respiratory depression. Results were analyzed by the ANOVA, a Chi square test, the Mann Whitney U test and by Fisher's exact test. P values of less than 0.05 were considered to be significant. Results: Postoperative pain and fentanyl consumption were significantly reduced by methylprednisolone, etoricoxib and their combination when compared with placebo (P<0.05). The methylprednisolone + etoricoxib combination caused a significant reduction in postoperative pain and fentanyl consumption as compared to methylprednisolone or etoricoxib alone (P<0.05); however, there was no significant difference between the methylprednisolone and etoricoxib groups (P>0.05). The methylprednisolone and methylprednisolone + etoricoxib combination significantly reduced the incidence and severity of PONV and fatigue as well as the total number of patients requiring an antiemetic treatment compared to the placebo and etoricoxib (P<0.05). Conclusions: A preoperative single-dose administration of a combination of methylprednisolone and etoricoxib reduces postoperative pain along with fentanyl consumption, PONV, antiemetic requirements and fatigue more effectively than methylprednisolone or etoricoxib alone or a placebo.

• Restorative Dentistry and Endodontics
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• v.13 no.2
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• pp.323-334
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• 1988

The purpose of this study was to observe the effect of dentin surface conditioners on the dentin surfaces. Freshly extracted human molars were used in this study. They were stored at $4^{\circ}C$ saline solution before experiment. The crown portions of the teeth were cut in various directions by means of wet diamond point to expose dentin which include transverse, vertical oblique, horizontal and oblique cut to the long axis (Fig. 1). Each tooth was then mounted with self curing acrylic resin in brass ring to expose the flattened dentin surfaces. Final finish was accomplished by grinding the dentin specimens with wet No. 180 and No. 600 grit silicon carbide abrasive paper until a 6.0mm in diameter on a dentin surface was exposed without pulp exposure. The specimens were divided into 9 groups according to the modes of dentin treatment procedure. The following surface treatments were applied on these preparation surfaces; Group 1: unetched (control group) after finish with No. 600 silicon carbide abrasive paper. Group 2: etched with 30% phosphoric acid for 60s Group 3: etched with 10-3 solution for 60s Group 4: Cleaned with 5% NaOCl for 30s Group 5: applied Dentin Adhesit Group 6: cleaned with 5% NaOCl followed by applying the Dentin Adhesit$^{(R)}$ Group 7: applied Photo Bond on the unetched dentin followed by applying the Photo Clearfil Bright Group 8: Etched with 30% phosphoric acid followed by applying Photo Bond and Photo Clearfil Bright Group 9: etched with 10-3 solution followed by applying Photo Bond and Photo Clearfil Bright All the specimens were stored in $37^{\circ}C$ under 50% relative humidity for 24 hours before observations. The specimens in 7, 8, and 9 group, omitting the group 1 to 6, were demineralized in 10% HCl for 10s in order to observe the resin tags. All the specimens in each group were then dried at room temperature. The dried specimens were ion coated with Eiko ion coater (Eiko-engineering Co.), and observed in Hitachi S-430 Scanning electron microscope (Hitachi, Co. Tokyo) at 15KV. The following results were obtained as follows; 1. The smear layers were still remained in group 1,2,4,5, and 6. 2. There is no effect of 5% NaOCl and 30% phosphoric acid on the changes of dentin morphology 3. The dentin treated with 10-3 solution, indicating the tubules opened when the smear layer and the dental plug dissolved. 4. In case of applying the bonding agents the resin tag was not formed at the deep area of dentinal tubules, but in case of applying the Dentin Adhesit$^{(R)}$ that was not.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.3
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• pp.243-249
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• 2001

Statement of the problem. The interest in all-ceramic restorations has increased as more techniques have become available. With the introduction of machinable dental ceramics and CAD/CAM systems or Copy-milling systems there is a need for evaluating the quality levels of these new fabrication techniques. Purpose. This study was to evaluate the fitting accuracy of machined all-ceramic crowns made out of an industrially prefabricated feldspathic porcelain. Material and Methods. Three master models with different cutting depth (0.8mm/1.0mm/1.2mm)were produced using a palladium-silver alloy. A total of 36 working dies, 12 of each form, was used for the modellation of prototype resin copings and 36 additional crowns, 12 of each cutting depth, were produced by using the $CEREC^{(R)}2$ system for all crowns. The maginal fit of all 72 crowns was then evaluated on their respective master die at 54 circularly staggered points of measurement per crown under a fixation pressure of 30 N by using a computerized video image system. Results. The medians of the copy-milled $CELAY^{(R)}$ crowns ranged from 29 to $36{\mu}m$. The highest value for the marginal gap was found in group B (cutting depth 1.0mm) at $107{\mu}m$. The median for the $CEREC^{(R)}2$ crowns was found between 43.5 and $70{\mu}m$. The maximum values for all three groups ranged from $181{\mu}m$ to $286{\mu}m$. With $286{\mu}m$ the highest value for marginal gap was found in group C. the Kruskal-Wallis test and multiple comparisons analysis procedure revealed a significant influence of the production technique on the marginal fit in all three groups (p<0,02). Conclusion. 1. The $CELAY^{(R)}$ system is capable to produce all-ceramic crowns with a significantly better marginal fit than the $CEREC^{(R)}2$ system. 2. As far as premolar crowns produced with the $CEREC^{(R)}2$ system are concerned, the cutting depth has a significant influence on fitting accuracy. 3. The production of crowns with an acceptable marginal fit is possible with both systems. However, adhesive luting is recommended for milled feldspathic porcelain crowns.