• The Journal of Korean Academy of Prosthodontics
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• v.45 no.3
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• pp.362-374
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• 2007

Statement of problem. The intial stability for osseointegration of implant has been an interesting factor. Especially, in the case of poor bone quality or immediately loaded implant, various strategies have been developed focusing on the surface of materials to improve implant fixation to bone. The microscopic properties of implant surfaces play a major role in the osseous healing of dental implants. Purpose. The aims of this study are to perform a histologic and histomorphometric comparison of the healing characteristics of three different surfaces and the comparison of resonance frequency analysis (RFA) values measured by $Osstell^{TM}$ and perio-test values (PTV) measured by Periotest. Material and methods. A total of 24 screw titanium implants (Dentium Co., Seoul, Korea) with 6mm in length and 3.4mm in diameter, were placed in the mandible of 4 beagle dogs. Implants were divided into three groups following the surface treatment methods: Group I is machined(control group). Group II is anodically oxidized. Group III is coated 500nm in thickness with hydroxyapatite(HA) by ion beam assisted deposition(IBAD) on the anodized oxidization. Bone blocks from 2 dogs were caught after 3 weeks of covered healing and another blocks from 2 dogs after 6 weeks. RFA values and PTV were measured right after insertion and at 3 and 6weeks. Histomorphometric analysis was made with Kappa Image Base System to calculate bone-to-implant contact (BIC) and bone area inside the threads. Pearson's correlation analyses were performed to evaluate the correlation between RFA and PTV, BIC and bone area ratio of three different surfaces at 3 and 6 weeks. Results. 1) In all surface treatment methods, the RFA values decreased and the PTV values increased until 6 weeks in comparison to initial values. 2) At 3 weeks, no significant difference was found from bone-to-implant contact ratio and bone area ratio of three different surface treatment methods(P>0.05). However, at 6 weeks, different surface treatment methods showed significantly different bone-toimplant contact ratio and bone area ratio(P<0.05). 3) In the implants with the IBAD on the anodic oxidization, significant difference was found between the 3 weeks and the 6 weeks bone area ratio(P<0.05). 4) Correlation was found between the RFA values and the bone area ratio at 3 and 6 weeks with significant difference(P<0.05). Conclusions. These results indicate that the implants with the IBAD on the anodic oxidization may have a high influence on the initial stability of implant.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.1
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• pp.26-34
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• 2003

Intraoral Vertical Ramus Osteotomy,along with Sagittal Split Ramus Osteotomy,is an popular surgical technique performed on mandibular prognathism. However Intraoral Vertical Ramus Osteotomy has been suspected for an initial mobilization at the healing phase of segment because it does not employ the rigid fixation between segments. To execute a study on the healing phase of segment after Intraoral Vertical Ramus Osteotomy on the horizontal plane, 102 patients (204 parts) who were diagnosed mandibular prognathism and took Intraoral Vertical Ramus Osteotomy at the Yonsei University dental hospital were observed during the period of before operation, immediately postoperation, 1 month, 3 months, 6 months, and 12 months. The change in the width of segment and horizontal angle of proximal segment and condylar head on the Submentovertex Cephalogram taken from those patients represented following results. 1. The width of proximal and distal segment decreased with the lapse of time. It decreased into 84.5% between immediate postoperative and 6M and even continued to decrease till 12M. 2. The horizontal angle of the proximal segment did medial rotation according as the lapse of time and rigorously continued till 3M. The rotation angle of condylar head indicated its tendency of recurrence to the original position but the entire recurrence was not allowed. The bigger an initial angle was, the higher was the tendency of recurrence after the operation while the rotation angle remained still bigger. 3. After grouping into group 1, group 2,and group 3 based on the extent of the variation of rotation angle of condylar head at immediate postoperative, the variation of rotation angle was measures in each group. The result presented that the initial rotation angle of condylar head had correlation with that of proximal segment but had no relation with the extent of setback of the mandible. However a quantitative analysis alone is not a sufficient method for analyzing the healing phase of segment on the horizontal plane.Therefore a multilateral analysis using 3 dimensional data such as CT is recommendable for the future study.

• Journal of Periodontal and Implant Science
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• v.47 no.3
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• pp.143-153
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• 2017

Purpose: The aim of the present exploratory study was to evaluate extraction socket healing at sites with a history of periodontal and endodontic pathology. Methods: The mandibular 4th premolar teeth in 5 adult beagle dogs served as experimental units. Periodontal and endodontic lesions were induced in 1 premolar site in each animal using wire ligatures and pulpal exposure over 3 months (diseased sites). The contralateral premolar sites served as healthy controls. The mandibular 4th premolar teeth were then extracted with minimal trauma, followed by careful wound debridement. The animals were sacrificed at days 1, 7, 30, 60, and 90 post-extraction for analysis, and the healing patterns at the healthy and diseased extraction sites were compared using radiography, scanning electron microscopy, histology, and histometry. Results: During the first 7 days of healing, a significant presence of inflammatory granulation tissue was noted at the diseased sites (day 1), along with a slightly accelerated rate of fibrin clot resolution on day 7. On day 30, the diseased extraction sites showed a greater percentage of persistent fibrous connective tissue, and an absence of bone marrow formation. In contrast, healthy sites showed initial signs of bone marrow formation on day 30, and subsequently a significantly greater proportion of mature bone marrow formation on both days 60 and 90. Radiographs exhibited sclerotic changes adjoining apical endodontic lesions, with scanning electron microscopy showing collapsed Volkmann canals protruding from these regions in the diseased sites. Furthermore, periodontal ligament fibers exhibited a parallel orientation to the alveolar walls of the diseased sites, in contrast to a perpendicular arrangement in the healthy sites. Conclusions: Within the limitations of this study, it appears that a history of periodontal and endodontic pathology may critically affect bone formation and maturation, leading to delayed and compromised extraction socket healing.

• Clinics in Shoulder and Elbow
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• v.8 no.2
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• pp.117-121
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• 2005

A secure slip knot is very important in the arthroscopic surgery of the shoulder joint. The new 'Hallym Slider', developed by the first author(KCN), has the properties of being a simple sliding and one-way locking knot. This technique can be performed alone without an assistant and has no accidental premature locking during the knot tying. The initial slip knot determines the adequacy of tissue approximation and consequent healing. The 'Hallym Slider' has excellent initial holding capacity, maintaining tension on soft tissue while additional half-hitches are being tied. It locks readily, it takes less time to tie than numerous square knots, and it is not as bulky as other knots. Therefore, we introduce this new sliding and one-way locking knot during the arthroscpic surgery of shoulder.

• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.371-376
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• 1998

This study presents an evaluation of the effectiveness of nonsurgical subgingival scaling and root planing related to initial pocket depth, type of teeth, and individual root surfaces. A total of 110 teeth designated for periodontal surgery in 67 patients with marginal periodontitis were selected and received thorough scaling and root planing with standard rigid Gracey curettes. After a healing period of 4 to 8 weeks, residual calculus was assessed at the time of periodontal surgery following the reflection of mucoperiosteal flap. The results demonstrated a high correlation between the percentage of residual calculus and initial pocket depth. It was further noted that tooth type and involved root surface also influenced the rate of calculus remnant. The results of this study suggest that complete removal of subgingival calculus utilizing conventional instrumentation via closed approach is rare.

• Journal of Power Electronics
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• v.13 no.1
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• pp.94-103
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• 2013

A capacitor deterioration of LCL-filter grid-connected PWM converters is progressed by the self-healing mechanism. It leads to the degradation of the filter performance and drop of power factor. Thus, it is required to diagnose fault-point of capacitors and determine the replacement time. Typically, the fault of capacitors is determined when the capacitance is reduced up to 80% from initial value. This paper proposes algorithm to the determine capacitor replacement time of an LCL filter. The algorithm takes the advantage of change of the response on the injected resonant frequency corresponding to 80% value from the initial capacitance. The results of the algorithm are demonstrated through simulations and experiments.

• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.3
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• pp.143-157
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• 2015

Successful integration of cementless femoral stems using porous surfaces relies on effective periimplant bone healing to secure the bone-implant interface. The initial stages of the healing process involve protein adsorption, fibrin clot formation and cell osteoconduction onto the implant surface. Modelling this process in vitro, the current work considered the effect of fibrin deposition on the responses of human mesenchymal stromal cells cultured on ferritic fibre networks intended for magneto-mechanical actuation of in-growing bone tissue. The underlying hypothesis for the study was that fibrin deposition would support early stromal cell attachment and physiological functions within the optimal regions for strain transmission to the cells in the fibre networks. Highly porous fibre networks composed of 444 ferritic stainless steel were selected due to their ability to support human osteoblasts and mesenchymal stromal cells without inducing untoward inflammatory responses in vitro. Cell attachment, proliferation, metabolic activity, differentiation and penetration into the ferritic fibre networks were examined for one week. For all fibrin-containing samples, cells were observed on and between the metal fibres, supported by the deposited fibrin, while cells on fibrin-free fibre networks (control surface) attached only onto fibre surfaces and junctions. Initial cell attachment, measured by analysis of deoxyribonucleic acid, increased significantly with increasing fibrinogen concentration within the physiological range. Despite higher cell numbers on fibrin-containing samples, similar metabolic activities to control surfaces were observed, which significantly increased for all samples over the duration of the study. It is concluded that fibrin deposition can support the early attachment of viable mesenchymal stromal cells within the inter-fibre spaces of fibre networks intended for magneto-mechanical strain transduction to in-growing cells.

• Journal of Korean Foot and Ankle Society
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• v.25 no.2
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• pp.100-107
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• 2021

Purpose: The present study aimed to develop guidelines regarding initial choice of antibiotics for diabetic foot ulcers (DFU) by investigating bacterial isolates. Materials and Methods: This study included 223 DFU patients that visited a single tertiary hospital and underwent bacterial culture between January 2016 and February 2020. The study was conducted in two parts: 1) to compare bacterial isolates and wound healing according to comorbidities such as chronic kidney disease (CKD) and peripheral artery disease (PAD), and 2) to compare bacterial isolates according to wound depth using the Wagner classification. Results: Of the 223 patients, 43 had CKD (group A), 56 had PAD (group B), 30 had CKD and PAD (group C), and 94 had none of these comorbidities (group D). The isolation rate for multidrug-resistant gram-negative bacteria (MRGNB) and gram-negative to gram-positive bacteria ratio were highest in group C (p=0.018, p=0.038), and the proportion that achieved wound healing was lowest in group C (p<0.001). In the second part of the study, subjects were classified into 5 grades by wound depth using the Wagner classification; 13 grade I, 62 grade II, 60 grade III, 70 grade IV, and 17 grade V. No significant difference was observed between these grades in terms of isolation rates or gram-negative to gram-positive bacteria ratios. Conclusion: This study suggests antibiotics that cover gram-negative bacteria including MRGNB produces better results in the presence of CKD and PAD and that initial antibiotic choice should be based on the presence of CKD and PAD rather than wound depth.

• Journal of Korean Dental Science
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• v.4 no.2
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• pp.67-72
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• 2011

Purpose: This study sought to evaluate the effects of bone graft wedging on the initial stability of implants in bone sites of unfavorable quality. Materials and Methods: Three male beagle dogs were used in this study. Osteotomies were performed with parallel drills (${\O}4.1{\times}10mm$), and fixtures (${\O}3.3{\times}8mm$) were placed. The control group was given implants without bone graft. Experiment group A was given implants with minimal initial stability using autobone grafts, whereas experiment group B was given xenografts. Groups were also divided by healing times at 4, 8, and 12 weeks. Results: All implants in the control group failed to osseointegrate. On the other hand, all implants in the experiment groups were clinically well-maintained during the entire experiment period. After 4, 8, and 12 weeks, bone-to-implant contact (BIC) ratio and implant stability quotient (ISQ) increased in the experiment groups. The differences between experiment groups A and B were not statistically significant, however. Conclusion: In unfavorable bone regions for dental implants, bone graft packing into the osteotomy prior to implant placement secured minimal initial stability and showed reasonable BIC ratios and ISQ values throughout the study period.

• Archives of Reconstructive Microsurgery
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• v.10 no.1
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• pp.49-54
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• 2001

Sutures support wound healing during the initial phase. As the tensile strength of a wound increases, the need for the presence of sutures becomes less important. For this reason, absorbable suture materials have been sought. Nowadays, commonly used suture materials are Chromic Catgut, Coated Vicryl, and PDS. Among these materials, Coated Vicryl is the most popular. Studies were conducted to compare the handling properties, reliability of knots, wound healing, and tissue reactivity(Inflammation, Fibroblast proliferation, Collagen deposition, Giant cell reaction, Absorption) between AILEE vicryl and ETHICON vicryl. We used twelve purebred New Zealand white rabbits, and biopsied the tissue at three, seven, fourteen, and thirty days post implantation. The results showed that both were supple and easy to handle and tie, and gross and histologic differences were not apparent.