• Imaging Science in Dentistry
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• v.33 no.2
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• pp.71-77
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• 2003

Purpose : To evaluate and compare the efficacy of digital radiographic images in the detection of bone loss at the bifurcation area of the mandibular first molar with traditional film-based periapical radiographs, Materials and Methods : One dried human mandible with minimal periodontal bone loss around the first molar was selected and an artificial alveolar bone defect at the bifurcation area was serially prepared over 18 steps. Images were taken using a direct CCD-based system and with F-speed periapical films. The images were evaluated by seven interpreters (3 radiologists, 3 periodontologists, and 1 general dentist) using a 5-point confidence rating scale. Results : The readability of both periapical radiographs and digital image increased as the size of the artificial lesion and exposure time increased (p < 0.05). Periapical radiographs offered greater readability of smaller bone defects than digital images, and the coefficient of variation of mean score between periapical radiographs and digital images showed a significant difference. Conclusion : The experimental results indicate that a significant difference in the coefficient of variation of mean score exists between periapical radiographs and digital images, and that traditional film-based periapical images offer greater readability of smaller bone defects than digital images can presently offer.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.1
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• pp.36-48
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• 2008

To repair bone defects in the oral and maxillofacial field, bone grafts including autografts, allografts, and artificial bone are used in clinical dentistry despite several disadvantages. The purpose of this study was to evaluate new bone formation and healing in rat calvarial bone defects using hydroxyapatite (HA, $Ca_{10}[PO_4]_6[OH]_2,\;Bongros^{(R)}$, Bio@ Co., KOREA) and tricalcium phosphate (${\beta}-TCP,\;Ca_3[PO_4]_2$, Sigma-Aldrich Co., USA) mixed at various ratios. Additionally, this study evaluated the effects of type I collagen (Rat tail, BD Biosciences Co., Sweden) as a basement membrane organic matrix. A total of twenty, 8-week-old, male Sprague-Dawley rats, weighing 250-300g, were divided equally into a control group (n=2) and nine experimental groups (n=2, each). Bilateral, standardized transosseous circular calvarial defects, 5.0 mm in diameter, were created. In each experimental group, the defect was filled with HA and TCP at a ratio of 100:0, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, and 0:100 with or without type I collagen. Rats were sacrificed 4 and 8 weeks post-operation for radiographic (standardized plain film, Kodak Co., USA), histomorphologic (H&E [Hematoxylin and Eosin], MT [Masson Trichrome]), immunohistochemical staining (for BMP-2, -4, VEGF, and vWF), and elementary analysis (Atomic absorption spectrophotometer, Perkin Elmer AAnalyst $100^{(R)}$). As the HA proportion increased, denser radiopacity was seen in most groups at 4 and 8 weeks. In general radiopacity in type I collagen groups was greater than the non-collagen groups, especially in the 100% HA group at 8 weeks. No new bone formation was seen in calvarial defects in any group at 4 weeks. Bridging bone formation from the defect margin was marked at 8 weeks in most type I collagen groups. Although immunohistochemical findings with BMP-2, -4, and VEGF were not significantly different, marked vWF immunoreactivity was present. vWF staining was especially strong in endothelial cells in newly formed bone margins in the 100:0, 80:20, and 70:30 ratio type I collagen groups at 8 weeks. The calcium compositions from the elementary analysis were not statistically significant. Many types of artificial bone have been used as bone graft materials, but most of them can only be applied as an inorganic material. This study confirmed improved bony regeneration by adding organic type I collagen to inorganic HA and TCP mixtures. Therefore, these new artificial bone graft materials, which are under strict storage and distribution systems, will be suggested to be available to clinical dentistry demands.

• Macromolecular Research
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• v.16 no.4
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• pp.345-352
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• 2008

Poly(lactic-co-glycolic acid) (PLGA) tubes (5 mm in diameter) were fabricated using an electro spinning method and used as a scaffold for artificial blood vessels through the hybridization of smooth muscle cells (SMCs) and endothelial cells (ECs) differentiated from canine bone marrow under previously reported conditions. The potential clinical applications of these artificial blood vessels were investigated using a canine model. From the results, the tubular-type PLGA scaffolds for artificial blood vessels showed good mechanical strength, and the dual-layered blood vessels showed acceptable hybridization behavior with ECs and SMCs. The artificial blood vessels were implanted and substituted for an artery in an adult dog over a 3-week period. The hybridized blood vessels showed neointimal formation with good patency. However, the control vessel (unhybridized vessel) was occluded during the early stages of implantation. These results suggest a shortcut for the development of small diameter, tubular-type, nanofiber blood vessels using a biodegradable material (PLGA).

• Journal of Biomedical Engineering Research
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• v.15 no.3
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• pp.341-346
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• 1994

To develop an artificial bone substitute that is gradually degraded and replaced by the regenerated natural bone, the authors designed a composite that is consisted of calcium phosphate and collagen. To use as the structural matrix of the composite, collagen was purified from human umbilical cord. The obtained collagen was treated by pepsin to remove telopeptides, and finally, the immune-free atel- ocollagen was produced. The cross linked atelocollagen was highly resistant to the collagenase induced collagenolysis. The cross linked collagen demonstrated an improved tensile strength.

• Journal of the Korean institute of surface engineering
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• v.29 no.2
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• pp.81-92
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• 1996

The cementless fixation of bone ingrowth by porous coatings on artificial hip joint prostheses are replacing polymethylmethacrylate(PMMA) bone cement fixations. However, the major interests in the field of porous metal coating are environmental corrosivity accelerated by metal ion release, deterioration in the mechanical property of the coating, and the mechanical failure of the coatings as well as the substrate. Therefore, the selection of right materials for coatings and the development of porous coating techniques must be accomplished. Because of the existing problems in Ti and Ti alloys which are used extensively, this study is focused on the plasma spraying technique for coating on super stainless steel substrate. In order to determine the optimum conditions which satisfy the requirement for the porous coatings, under the plasma spraying, we selected the experimental parameters which extensively influenced on the characteristics of the coating through the pre-examination. Spray distance has been selected among 120, 160, and 200mm and primary gas flow rate among 70, 100, and 130 SCFH. Current and secondary gas($H_2$) flow rate was fixed at 400A, and 15 SCFH respectively. To understand the characteristics of the coatings, surface morphology, cross-sectional micro-structure, surface roughness, residual stress, and corrosion resistance were elucidated and the best conditions for the bone ingrowth improvement on artificial hip joint prostheses were found.

• Korean Journal of Radiology
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• v.22 no.12
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• pp.2017-2025
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• 2021

Objective: To evaluate the accuracy and clinical efficacy of a hybrid Greulich-Pyle (GP) and modified Tanner-Whitehouse (TW) artificial intelligence (AI) model for bone age assessment. Materials and Methods: A deep learning-based model was trained on an open dataset of multiple ethnicities. A total of 102 hand radiographs (51 male and 51 female; mean age ± standard deviation = 10.95 ± 2.37 years) from a single institution were selected for external validation. Three human experts performed bone age assessments based on the GP atlas to develop a reference standard. Two study radiologists performed bone age assessments with and without AI model assistance in two separate sessions, for which the reading time was recorded. The performance of the AI software was assessed by comparing the mean absolute difference between the AI-calculated bone age and the reference standard. The reading time was compared between reading with and without AI using a paired t test. Furthermore, the reliability between the two study radiologists' bone age assessments was assessed using intraclass correlation coefficients (ICCs), and the results were compared between reading with and without AI. Results: The bone ages assessed by the experts and the AI model were not significantly different (11.39 ± 2.74 years and 11.35 ± 2.76 years, respectively, p = 0.31). The mean absolute difference was 0.39 years (95% confidence interval, 0.33-0.45 years) between the automated AI assessment and the reference standard. The mean reading time of the two study radiologists was reduced from 54.29 to 35.37 seconds with AI model assistance (p < 0.001). The ICC of the two study radiologists slightly increased with AI model assistance (from 0.945 to 0.990). Conclusion: The proposed AI model was accurate for assessing bone age. Furthermore, this model appeared to enhance the clinical efficacy by reducing the reading time and improving the inter-observer reliability.

• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.670-675
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• 2016

Calcium phosphate crystallites were prepared by wet chemical method for use in artificial bone. In order to obtain ${\beta}$-tricalcium phosphate (TCP), nano-crystalline calcium phosphate (CaP) was precipitated at $37^{\circ}C$ and at $pH5.0{\pm}0.1$ under stirring using highly active $Ca(OH)_2$ in DI water and an aqueous solution of $H_3PO_4$. The precipitated nano-crystalline CaP solution was kept at $90^{\circ}C$ for the growth of CaP crystallites. Through the growing process of CaP crystallites, we were able to obtain various sizes of rectangular CaP crystallites according to the crystal growing times. Dry nano-crystalline CaP powders at $37^{\circ}C$ were mixed with dry macro-crystalline CaP crystallites and the shaped mixture sample was fired at $1150^{\circ}C$ to make a ${\beta}-TCP$ block. Several tens of nm powders were uniformly coated on the surface, which was comprised of powders of several tens of ${\mu}m$, using a vibrator. The mixing ratio between the nanometer powders and the micrometer powders greatly affected the mechanical strength of the mixture block; the most appropriate ratio of these two materials was 50 wt% to 50 wt%. The sintered block showed improved mechanical strength, which was caused by the solid state interaction between the nano-crystalline ${\beta}-TCP$ and the macro-crystalline ${\beta}-TCP$.

• Archives of Plastic Surgery
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• v.39 no.4
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• pp.390-396
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• 2012

Background The radial forearm osteocutaneous free flap is considered to be the standard technique for penile construction. One year after their operation, most patients experience a softened phallus, so that they suffer from difficulties in sexual intercourse. In this report, we present our experience with phalloplasty by radial forearm osteocutaneous free flap, as well as an evaluation of the etiology and treatment of the softened phallus. Methods Between March 2005 and February 2010, 58 patients underwent phalloplasty by radial forearm osteocutaneous free flap. Most of their neophallus had been softened subjectively and among them, 12 patients who wanted correction were investigated. We performed repetitive fat injection, artificial dermis grafting, silicone rod insertion, and rib bone with cartilaginous tip graft. Physical examination, plain radiograph, computed tomography, bone scintigraphy, and satisfaction scores were investigated. Results Most of the participants' penises have been softened after phalloplasty, and the skin elasticity had been also decreased. On plain radiograph, the distal end of the bone was self-rounded; however, the bone shape of the neophallus had no significant interval changes or resorption. Computed tomography showed equivocal density of cortical bone. On bone scintigraphy, the bone metabolism was active at 3 months postoperatively, and remained active 9 years postoperatively. Conclusions The use of a rib bone with cartilaginous tip graft could be an option for improvement of the softened phallus. Silicon rod insertion is also worth considering for rigidity of the softened phallus. Decreased rigidity due to soft tissue atrophy could be alleviated with repeated fat injection and artificial dermis grafting.

• Journal of Periodontal and Implant Science
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• v.29 no.3
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• pp.483-509
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• 1999

Biodegradable barrier membrane has been demonstrated to have guided bone regeneration capacity on the animal study. The purpose of this study is to evaluate the effects of cultured calvarial cell inoculated on the biodegradable barrier membrane for the regeneration of the artificial bone defect. In this experiment 35 Sprague-Dawley male rats(mean BW 150gm) were used. 30 rats were divided into 3 groups. In group I, defects were covered periosteum without membrane. In group II, defects were repaired using biodegradable barrier membrane. In group III, the defects were repaired using biodegradable barrier membrane seeded with cultured calvarial cell. Every surgical procedure were performed under the general anesthesia by using with intravenous injection of Pentobarbital sodium(30mg/Kg). After anesthesia, 5 rats were sacrificed by decapitation to obtain the calvaria for bone cell culture. Calvarial cells were cultured with Dulbecco's Modified Essential Medium contained with 10% Fetal Bovine Serum under the conventional conditions. The number of cell inoculated on the membrane were $1{\times}10^6$ Cells/ml. The membrane were inserted on the artificial bone defect after 3 days of culture. A single 3-mm diameter full-thickness artificial calvarial defect was made in each animal by using with bone trephine drill. After the every surgical intervention of animal, all of the animals were sacrificed at 1, 2, 3 weeks after surgery by using of perfusion technique. For obtaining histological section, tissues were fixed in 2.5% Glutaraldehyde (0.1M cacodylate buffer, pH 7.2) and Karnovsky's fixative solution, and decalcified with 0.1M disodium ethylene diaminetetraacetate for 3 weeks. Tissue embeding was performed in paraffin and cut parallel to the surface of calvaria. Section in 7${\mu}m$ thickness of tissue was done and stained with Hematoxylin-Eosin. All the specimens were observed under the light microscopy. The following results were obtained. 1 . During the whole period of experiment, fibrous connective tissue was revealed at 1week after surgery which meant rapid soft tissue recovery. The healing rate of defected area into new bone formation of the test group was observed more rapid tendency than other two groups. 2 . The sequence of healing rate of bone defected area was as follows ； test group, positive control, negative control group. 3 . During the experiment, an osteoclastic cell around preexisted bone was not found. New bone formation was originated from the periphery of the remaing bone wall, and gradually extended into central portion of the bone defect. 4 . The biodegradable barrier membrane was observed favorable biocompatibility during this experimental period without any other noticeable foreign body reaction. And mineralization in the newly formed osteoid tissue revealed relatively more rapid than other group since early stage of the healing process. Conclusively, the cultured bone cell inoculated onto the biodegradable barrier membrane may have an important role of regeneration of artificial bone defects of alveolar bone. This study thus demonstrates a tissue-engineering the approach to the repair of bone defects, which may have clinical applications in clinical fields of the dentistry including periodontics.

• Journal of Veterinary Clinics
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• v.31 no.1
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• pp.46-50
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• 2014

A 7-year-old spayed female Welsh corgi presented with a mass of the skull. The mass was diagnosed as multilobular bone tumor and surgically removed. To treat a large bone defect after the tumor removal, custom-made artificial bone fabricated by a 3-dimensional ink-jet printer was implanted in the defect. Follow-up computed tomography evaluation was performed for 4.3 years. The implant was well integrated with the skull and had covered the large bone defect during the follow-up period. Gradual degradation of the implant began 6 weeks after surgery. It provides an additional option for the treatment of large bone defect.