• Journal of the Korean Ceramic Society
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• v.47 no.4
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• pp.343-352
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• 2010

A zirconia gel/polymer hybrid nanofiber was produced in a nonwoven fabric mode by electrospinning a sol derived from hydrolysis of zirconium butoxide with a polyvinyl butyral. Results indicated that the hydroxyl groups on the vinyl alcohol units in the backbone of the polymer were involved in the hydrolysis as well as grafting the hydrolyzed zirconium butoxide. In addition, use of acetic acid as a catalyst resulted in further hydrolysis and condensation in the sol, which led to the growth of -Zr-O-Zr- networks among the polymer chains. These networks gradually transformed into a crystalline zirconia structure upon heating. The as-spun fiber was smooth but partially wrinkled on the surface. The average fiber diameter was $690{\pm}110\;nm$. The fiber exhibited a strong but broad blue photoluminescence with its maximum intensity at a wavelength of ~410 nm at room temperature. When the fiber was heat-treated at $400^{\circ}C$, the fiber diameter shrunk to $250{\pm}60\;nm$. Nanocrystals which belonged to a tetragonal zirconia phase and were ~5 nm in size appeared. A strong white photoluminescence was observed in this fiber. This suggests that oxygen or carbon defects associated with the formation of the nanocrystals play a role in generating the photoluminescence. Further heating to $800^{\circ}C$ resulted in a monoclinic phase beginning to form In the heat-treated fibers, coloring occurred but varied depending on the heating temperature. Crystallization, coloring, and phase transition to the monoclinic structure influenced the photoluminescence. At $600^{\circ}C$, the fiber appeared to be fully crystallized to a tetragonal zirconia phase.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.276-292
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• 1996

The purpose of this study was to evaluate whether removal of gingival epithelium with pulsed Nd :YAG laser could inhibit the downgrowth of junctional epithelium after alloplastic material grafting in periodontal bone defect. The periodontal bone defects were created surgically on the palatal aspect of the upper right and left molar teeth in 30 rats and filled with resorbable calcium carbonate($Biocoral\;450^{(R)}$: Inoteb, France). The control sites(right molar area) was sutured. The test side (left molar area) received controlled deepithelization of the oral and sulcular epithelium with pulsed Nd:YAG laser($Sunrise\;Maste^{(R)}$: Sunrise Technologies, U.S.A.) under the mode of 1.75W, 15Hz, 116mJ/pulse and was sutured. The control and test sites were evaluated clinically and histologically, at 1, 3, 7, 14, and 28 days postoperation. Clinically, the gingiva showed normal color and shape at the 5th day in the control site and at the 10th day in the test sites. Histologically, the junctional epithelium was formed at the 7th day in the control sites and at the 14th day in the test sites, and the long JE attachment were observed at the 28th day in both sites. The attachment of connective tissue to root surface was observed initially at the 7th day in the control sites and at the 14th day in the test sites, and completed at the 28th day in both sites. In summary, these results showed that the removal of oral epithelium using pulsed Nd:YAG Laser could not prevent epithelial downgrowth after alloplastic material implantation in rat periodontal bone defect.

• Polymer(Korea)
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• v.24 no.1
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• pp.1-7
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• 2000

The ACF/PP-g-AAc copolymers were synthesized by the irradiational grafting of acrylic acid onto ACF/PP fabric. The synthesis of copolymer was evidenced by the bands at 1720, 3600~3100 $cm^{-1}$ / on FT-IR spectrum. After the adsorption of metal ions on ACF/PP-g-AAc copolymers, the morphology with the small deposits on the fiber surface were observed by SEM. The optimal time for the metal ion adsorption equilibrium on ACF/PP-g-AAc copolymers was 24 hrs and their adsorption capacities increased in the order of Mn$^{2+}$>Cu$^{2+}$>Co$^{2+}$>Ni$^{2+}$. The adsorption capacities of ACF/PP-g-AAc copolymers were invariable after more than 10 times of regeneration.eration.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.157-158
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• 1998

The purpose of this study was to test the hypothesis that even very small change of the cue direction in the treatment of the early osteonecrosis could affect the outcomes of operation. For this, the changes in stress transfer within the necrotic area of the femoral head were investigated under various directions and placements of the core utilizing finite element method. The loading of 3188N, which represents after-heel-strike, was imposed in cubic cosine pattern. All nodes on the most distal surface of the model were constrained in all directions. All materials included were assumed to have linear-elastic behavior. The result says that the critical stress, which causes collapse of the femoral head, was reduced when the core was oriented toward the posterior side of the femoral head regardless of location of the necrotic area. The same result was obtained either fibular bone grafting or cementation was adopted. As a consequence, the biomechanical study suggests that the core should be directed toward the loading point where the resultant force is applied to get more desirable treatment of the osteonecrosis of the femoral head in the early stage.

• Archives of Plastic Surgery
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• v.34 no.3
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• pp.325-329
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• 2007

Purpose: Mobius syndrome is a rare congenital disorder characterized by facial diplegia and bilateral abducens palsy, which occasionally combines with other cranial nerve dysfunction. The inability to show happiness, sadness or anger by facial expression frequently results in social dysfunction. The classic concept of cross facial nerve grafting and free muscle transplantation, which is standard in unilateral developmental facial palsy, cannot be used in these patients without special consideration. Our experience in the treatment of three patients with this syndrome using transfer of muscles innervated by trigeminal nerve showed rewarding results. Methods: We used bilateral temporalis muscle elevated from the bony temporal fossa. Muscles and their attached fascia were folded down over the anterior surface of the zygomatic arch. The divided strips from the attached fascia were passed subcutaneously and anchored to the medial canthus and the nasolabial crease for smiling and competence of mouth and eyelids. For the recent 13 years the authors applied this method in 3 Mobius syndrome cases- 45 year-old man and 13 year-old boy, 8 year-old girl. Results: One month after the surgery the patients had good support and already showed voluntary movement at the corner of their mouth. They showed full closure of both eyelids. There was no scleral showing during eyelid closure. Also full closure of the mouth was achieved. After six months, the reconstructed movements of face were maintained. Conclusion: Temporalis muscle transfer for Mobius syndrome is an excellent method for bilateral reconstruction at one stage, is easy to perform, and has a wide range of reconstruction and reproducibility.

• Archives of Plastic Surgery
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• v.40 no.3
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• pp.259-262
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• 2013

After skin grafting, to prevent hematoma or seroma collection at the graft site, a tie-over dressing has been commonly used. However, although the conventional tie-over dressing by suture is a useful method for securing a graft site, refixation is difficult when repeated tie-over dressing is needed. Therefore, we recommend a redoable tie-over dressing technique with multiple loops threads and connecting silk threads. After the raw surface of each of our cases was covered with a skin graft, multiple loop silk thread attached with nylon at the skin graft margin. We applied the ointment gauze and wet cotton/fluffy gauze over the skin graft, then fixed the dressing by connecting cross-counter multiple loop thread with connecting silk threads. When we opened the tie-over dressing by cutting the connecting silk threads, we repeated the tie-over dressing with the same method. The skin graft was taken successfully without hematoma or seroma collection or any other complications. In conclusion, we report a novel tie-over dressing enabling simple fixation of the dressing to maintain proper tension for wounds that require repetitive fixation. Further, with this reliable method, the skin grafts were well taken.

• Macromolecular Research
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• v.14 no.1
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• pp.87-93
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• 2006

Copolymers composed of hyaluronic acid (HA) and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to create temperature-sensitive injectable gels for use in controlled drug delivery applications. Semi-telechelic PNIPAAm, with amino groups at the end of each main chain, was synthesized by radical polymerization using 2-aminoethanethiol hydrochloride (AESH) as the chain transfer agent, and was then grafted onto the carboxyl groups of HA using carbodiimide chemistry. The result of the thermo-optical analysis revealed that the phase transition of the PNIPAAm-grafted HA solution occurred at around 30$\∼$33$^{circ}C$. As the graft yield of PNIPAAm onto the HA backbone increased, the HA-g-PNIPAAm copolymer solution exhibited sharper phase transition. The short chain PNIPAAm-grafted HA ($M_{w}$=6,100) showed a narrower temperature range for optical turbidity changes than the long chain PNIPAAm-grafted HA ($M_{w}$=13,100). PNIPAAm-grafted HA exhibited an increase in viscosity above 35$^{circ}C$, thus allowing the gels to maintain their shape for 24 h after in vivo administration. From the in vitro riboflavin release study, the HA-g-PNIPAAm gel showed a more sustained release behavior when the grafting yield of PNIPAAm onto the HA backbone was increased. In addition, BSA released from the PNIPAAm-g-HA gels showed a maximum concentration in the blood 12 h after being injected into the dorsal surface of a rabbit, followed by a sustained release profile after 60 h.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.2
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• pp.140-147
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• 2012

Microvascular reconstruction, in the oral and maxillofacial regions, is a widely accepted as the best way to overcome the complex oral cavity defects. Many patients requiring composite reconstructions have been treated previously with radiation therapy, chemotherapy, selective and/or functional neck dissection or any of these combinations. In many cases of these patients, inadequate neck vessels for the microanastomosis of free flap are available, due to a lack of recipient vessels in the neck, poor vessel quality or vessel caliber mismatch. To achieve a tension-free anastomosis, vein grafting must be considered to span the vessel gap between the free flap pedicle and the recipient neck vessels. Although most microsurgeons believed that interpositional grafts are to be avoided due to vessel thrombosis and increased number of necessary microanastomosis, we, authors have some confidence of equivalency between reconstruction with and without interpositional saphenous vein graft. The great saphenous vein, also known as the long saphenous vein, is the large subcutaneous superficial vein of the leg and thigh. It joins with the femoral vein in the region of femoral triangle at the saphenofemoral junction, and coursed medially to lie on the anterior surface of the thigh before entering an opening in the fascia lata, called the saphenous opening. For a better understanding of the great saphenous vein graft for the interpositional vessel graft in the oral cavity reconstructions, and an avoidance of any uneventful complications during these procedures, the related surgical anatomies with their harvesting tips are summarized in this review article in the Korean language.

• Macromolecular Research
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• v.16 no.2
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• pp.139-148
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• 2008

Biodegradable and elastic poly(L-lactide-co-$\varepsilon$-caprolactone) (PLCL) was electrospun to prepare nanofibers, and N-isopropylacrylamide (NIPAAm) was then grafted onto their surfaces under aqueous conditions using $^{60}Co-{\gamma}$ irradiation. The graft yield increased with increasing irradiation dose from 5 to 10 kGy and the nanofibers showed a greater graft yield compared with the firms. SEM confirmed that the PLCL nanofibers maintained an interconnected pore structure after grafting with NIPAAm. However, overdoses of irradiation led to the excessive formation of homopolymer gels on the surface of thc PLCL nanofibers. The equilibrium swelling and deswelling ratio of the PNIPAAm-g-PLCL nanofibers (prepared with 10 kGy) was the highest among the samples, which was consistent with the graft yield results. The phase-separation characteristics of PNIPAAm in aqueous conditions conferred a unique temperature-responsive swelling behavior of PNIPAAm-g-PLCL nanofibers, showing the ability to absorb a large amount of water at < $32^{\circ}C$, and abrupt collapse when the temperature was increased to $40^{\circ}C$. In accordance with the temperature-dependent changes in swelling behavior, the release rate of indomethacin and FITC-BSA loaded in PNIPAAm-g-PLCL nanofibers by a diffusion-mediated process was regulated by the change in temperature. Both model drugs demonstrated greater release rate at $40^{\circ}C$ relative to that at $25^{\circ}C$. This approach of the temperature-controlled release of drugs from PNIPAAm-g-PLCL nanofibers using gamma-ray irradiation may be used to design drugs and protein delivery carriers in various biomedical applications.

• Archives of Craniofacial Surgery
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• v.22 no.2
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• pp.85-92
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• 2021

Background: Patients with secondary deformities associated with unilateral cleft lip and nose might also suffer from nostril stenosis due to a lack of tissue volume in the nostril on the cleft side. Here, we used full-thickness skin grafts (FTSGs) to reduce nostril stenosis and various methods for skin volume augmentation. We compared the changes in the symmetry of both nostrils before and after surgery. Methods: From February 2016 to January 2020, 34 patients underwent secondary cheiloplasty and open rhinoplasty for secondary deformities of the unilateral cleft lip and nose with nostril stenosis. FTSG was used on the nostril floor, nasal columella, and alar inner lining. The measured nasal profile included the nostril surface, nostril circumference, width of the nostril floor, and distance from the alar-facial groove to the nasal tip. The "overlap area," which was defined as the largest overlapping area when the image of the cleft nostril was flipped to the left and right and overlaid on the image of the normal side nostril, was also calculated. The degree of symmetry was evaluated by dividing the value of the cleft side by that of the normal side of each measured profile and expressed as "ratios." Results: The results of all profile ratios, except for the nostril floor width, became significantly close to 1, which represents full symmetry. The overlap area ratio improved from 62.7% to 77.3%, meaning that the length and width of the nostril as well as the overall shape became similar (p< 0.05). Conclusion: When performing cleft rhinoplasty with nostril stenosis, FTSG is useful to achieve symmetry in the nostril size and shape. Skin grafting is simpler to perform than the other types of local flap, and the results are generally satisfactory.