• Journal of Biosystems Engineering
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• v.43 no.1
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• pp.59-71
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• 2018

Purpose: Cellulose nanocrystals (CNCs) are natural polymers that have been promoted as a next generation of new, sustainable materials. CNCs are invaluable as reinforcing materials for composites because they can impart improved mechanical, chemical, and thermal properties and they are biodegradable. The purpose of this review is to provide researchers with information that can assist in the application of CNCs extracted from waste agricultural byproducts (e.g. rice husks, corncobs, pineapple leaves). Methods & Results: This paper presents the unique characteristics of CNCs based on agricultural byproducts, and lists processing methods for manufacturing CNCs from agricultural byproducts. Various mechanical treatments (microfluidization and homogenization) and chemical treatments (alkali treatment, bleaching and hydrolysis) can be performed in order to generate nanocellulose. CNC-based composite properties and various applications are also discussed. Conclusions: CNC-based composites from agricultural byproducts can be combined to meet end-use applications such as sensors, batteries, films, food packaging, and 3D printing by utilizing their properties. The review discusses applications in food engineering, biological engineering, and cellulose-based hydrogels.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.363-368
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• 2020

The prosthesis of the implant installed in inappropriate positions presents aesthetic and functional problems. If the implants are placed in the wrong position, re-implantation is often limited. There are surgical and non-surgical methods for resolving complications without re-implantation. The surgical costs, healing time, discomfort and unpredictability make this choice unpopular. On the other hand, a gingival mask has the advantage of solving complications quickly and simply. The patient was a 80-year-old male with palatally installed implant in maxillary anterior region and dissatisfied with his unesthetic philtrum and food impaction between the upper lip and the prosthesis. It was difficult to predict the prognosis of surgical operation, and the patient wanted treatment economically and physically burdenless because of his age and financial situation. Thus, the gingival mask was planned and the results were satisfactory.

• Polymer(Korea)
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• v.38 no.6
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• pp.815-819
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• 2014

Scaffolds of tissue engineering should be biocompatible and biodegradable for cell attachment, proliferation and differentiation. In the various scaffold fabrication, 3D printing technique can make the three dimensional scaffold with interconnected pores for cell ingrowth. Polycaprolactone (PCL) is biodegradable polyester with a low melting temperature and has been approved by the Food and Drug Administration (FDA). In this study, PCL scaffold was fabricated by 3D bioprinting system and surface modification of PCL scaffold was controlled by NaOH treatment. Morphological change and wetability of NaOH-treated scaffold were observed by SEM and contact angle measurement system. The remnant of PCL treated with NaOH was measured by ATR-FTIR. In vitro study of scaffolds was evaluated with WST-1 and ALP activity assay. NaOH treatment of PCL scaffolds increased surface roughness, hydrophilicity, cell proliferation and osteogenic differentiation. These results indicate that NaOH-treated PCL scaffold made by 3D bioprinting has tissue engineered potential for the development of biocompatible material.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.45 no.5
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• pp.276-284
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• 2019

Objectives: This study sought to compare efficiency results between the use of a customized implant (CI) and a reconstruction plate (RP) in mandibular defect reconstruction in an animal model. Materials and Methods: Fifteen rabbits underwent surgery to create a defect in the right side of the mandible and were randomly divided into two groups. For reconstruction of the mandibular defect, the RP group (n=5) received five-hole mini-plates without bone grafting and the CI group (n=10) received fabricated CIs based on the cone-beam computed tomography (CBCT) data taken preoperatively. The CI group was further divided into two subgroups depending on the time of CBCT performance preoperatively, as follows: a six-week CI (6WCI) group (n=5) and a one-week CI (1WCI) group (n=5). Daily food intake amount (DFIA) was measured to assess the recovery rate. Radiographic images were acquired to evaluate screw quantity. CBCT and histological examination were performed in the CI subgroup after sacrifice. Results: The 1WCI group showed the highest value in peak average recovery rate and the fastest average recovery rate. In terms of reaching a 50% recovery rate, the 1WCI group required the least number of days as compared with the other groups ($2.6{\pm}1.3days$), while the RP group required the least number of days to reach an 80% recovery rate ($7.8{\pm}2.2days$). The 1WCI group showed the highest percentage of intact screws (94.3%). New bone formation was observed in the CI group during histological examination. Conclusion: Rabbits with mandibular defects treated with CI showed higher and faster recovery rates and more favorable screw status as compared with those treated with a five-hole mini-plate without bone graft.