• The Journal of Advanced Prosthodontics
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• v.12 no.5
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• pp.316-321
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• 2020

PURPOSE. The stress distribution and microgap formation on an implant abutment structure was evaluated to determine the relationship between the direction of the load and the stress value. MATERIALS AND METHODS. Two types of three-dimensional models for the mandibular first molar were designed: bone-level implant and tissue-level implant. Each group consisted of an implant, surrounding bone, abutment, screw, and crown. Static finite element analysis was simulated through 200 N of occlusal load and preload at five different load directions: 0, 15, 30, 45, and 60°. The von Mises stress of the abutment and implant was evaluated. Microgap formation on the implant-abutment interface was also analyzed. RESULTS. The stress values in the implant were as follows: 525, 322, 561, 778, and 1150 MPa in a bone level implant, and 254, 182, 259, 364, and 436 MPa in a tissue level implant at a load direction of 0, 15, 30, 45, and 60°, respectively. For microgap formation between the implant and abutment interface, three to seven-micron gaps were observed in the bone level implant under a load at 45 and 60°. In contrast, a three-micron gap was observed in the tissue level implant under a load at only 60°. CONCLUSION. The mean stress of bone-level implant showed 2.2 times higher than that of tissue-level implant. When considering the loading point of occlusal surface and the direction of load, higher stress was noted when the vector was from the center of rotation in the implant prostheses.

• Clinics in Shoulder and Elbow
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• v.8 no.1
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• pp.19-22
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• 2005

Purpose: The causes of twelve cases of the mid-shaft clavicle nonunion and the results of internal fixation with plate and bone graft were investigated. Materials and method: From August 1997 to March 2003, twelve cases of the mid-shaft clavicle nonunion were operated with internal fixation with plate and bone graft. The duration of follow-up was average 13 months. Results: The causes of the mid-shaft clavicle nonunion included severe associated injury, severe initial displacement of the fracture fragments and insecure fixation. All cases were operated with internal fixation with plate and bone graft. According to the factor for evaluations of results, using a rating scale of excellent (no apparent factors), good (one factor), fair (two factors), poor (more than three factors), the results showed 10 excellent, 1 good and 1 poor. Screw loosening was developed in only one case . Conclusion: The internal fixation with plate and bone graft of the mid-shaft clavicle nonunion after failed conservative treatment achieved excellent results and seemed to be the procedure of choice for mid-shaft clavicle nonunion.

• Composites Research
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• v.23 no.6
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• pp.55-60
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• 2010

In this paper, tensile and bending tests of glass/polypropylene composite (Twintex) specimens fabricated by various forming conditions were carried out and the results were compared according to the forming conditions to find the appropriate condition for the forming composite bone plates. From the tests it was found that the most appropriate forming conditions were $230^{\circ}C$, 3MPa. Composite bone plates were formed using this condition by two different fabricating methods for screw holes: one was a net shape molding and the other was drilling. The forming and bending tests revealed that the drilling process provided much better bending stiffness of bone plates. This paper provided the most appropriate condition for forming composite bone plates and this result was also expected to offer informative data on forming of other Twintex structures.

• Journal of Periodontal and Implant Science
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• v.50 no.2
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• pp.106-120
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• 2020

Purpose: A new form of porous polyethylene, characterized by higher porosity and pore interconnectivity, was developed for use as a tissue-integrated implant. This study evaluated the effectiveness of porous polyethylene blocks used as an onlay bone graft in rabbit mandible in terms of tissue reaction, bone ingrowth, fibrovascularization, and graft-bone interfacial integrity. Methods: Twelve New Zealand white rabbits were randomized into 3 treatment groups according to the study period (4, 12, or 24 weeks). Cylindrical specimens measuring 5 mm in diameter and 4.5 mm in thickness were placed directly on the body of the mandible without bone bed decortication, fixed in place with a titanium screw, and covered with a collagen membrane. Histologic and histomorphometric analyses were done using hematoxylin and eosin-stained bone slices. Interfacial shear strength was tested to quantify graft-bone interfacial integrity. Results: The porous polyethylene graft was observed to integrate with the mandibular bone and exhibited tissue-bridge connections. At all postoperative time points, it was noted that the host tissues had grown deep into the pores of the porous polyethylene in the direction from the interface to the center of the graft. Both fibrovascular tissue and bone were found within the pores, but most bone ingrowth was observed at the graft-mandibular bone interface. Bone ingrowth depth and interfacial shear strength were in the range of 2.76-3.89 mm and 1.11-1.43 MPa, respectively. No significant differences among post-implantation time points were found for tissue ingrowth percentage and interfacial shear strength (P>0.05). Conclusions: Within the limits of the study, the present study revealed that the new porous polyethylene did not provoke any adverse systemic reactions. The material promoted fibrovascularization and displayed osteoconductive and osteogenic properties within and outside the contact interface. Stable interfacial integration between the graft and bone also took place.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.255-264
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• 1997

The conventional osseointegration protocol calls for waiting up to 12 months for ossification of an extraction socket to heal before placing an endosseous implant. In this study, the possibility of placing a pure titanium implant directly into an extraction socket immediately after extraction was investigated. And the marginal bone loss of immediate nonsubmerged and submerged endosseous dental implants placed into extraction sockets was also compared. Pure titanium Nobelpharma Branemark implants and solid screw type ITI implants were placed into premolar extraction sockets of two adult dogs and allowed to heal for a period of 3 months, followed by functional loading of the implant. Radiographic examination was performed before implantation, immediately after implantation and 3, 6, 9, 12 months after implantation. The results obtained were as follows : 1. Immediately placed nonsubmerged ITI implants and submerged Branemark implants showed favorable radiographic osseointegration status and there were minimum marginal bone loss. 2. There were no significant differences in radiographic finding of osseointegration between conventional and immediate implantation. 3. Gingival tissue around implants showed more inflammatory signs than that of adjacent natural teeth. This study suggest that pure titanium Branemark implants and submerged ITI implants have the potential to integrate when placed immediatly after extraction of the teeth and warrants further investigation.

• The Journal of Advanced Prosthodontics
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• v.2 no.2
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• pp.54-57
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• 2010

PURPOSE. The aim of this study was to evaluate the periodontal and prosthodontic complications of multiple freestanding implants in the posterior jaws for up to 1 year of function. MATERIALS AND METHODS. Eight patients received 20 implants posterior to canines. Two or more implants were consecutively inserted to each patient. Single crowns were delivered onto the implants. Marginal bone loss, implant mobility, probing depth, and screw loosening were examined to evaluate the clinical success of such restorations for maximum 1 year of functional loading. RESULTS. All the implants performed well during the observation period. Neither periodontal nor prosthodontic complications were found except a slight porcelain chipping. While the marginal bone level was on average 0.09 mm lower around the implant after 6 months of loading, it was 0.15 mm higher after 1 year. CONCLUSION. Within the limits of this investigation, separate single-tooth implant restorations to replace consecutive missing teeth may clinically function well in the posterior jaw.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.253-262
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• 2008

Background: Incomplete flap coverage or early exposure over implants and/or barrier membranes have a negative effect on bone regeneration. In cases of using regenerative techniques, complete soft tissue coverage of the implant area is necessary to promote adequate conditions for guided bone regeneration. Primary socket closure may be difficult, when periosteal releasing incision is only used, due to the opening left by extracted tooth. Therefore, Soft tissue grafting techniques are used to achieve primary soft tissue closure. Materials and Methods: Soft tissue grafting techniques, with or without barrier membranes, were performed for primary closure in four cases of immediate placements. Three different methods were used (CTG, VIP-CT, Palatal advanced flap). Clinical results of the grafting were evaluated. Result: One case showed early exposure of cover-screw and, no other complications were noted. In the others, Primary closure was achieved by soft tissue grafting techniques. One of the cases, Graft showed partial necrosis, but there were no exposure over implants and/or barrier membranes. Conclusion: The use of grafting techniques, in immediate implant placement, can predictably obtain primary closure of extraction sockets, thereby providing predictable bone formation and improved implant results.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup1
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• pp.108-114
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• 2001

Objective : Posterior lumbar interbody fusion(PLIF) provides the favorable outcome to degenerative lumbar disease, especially isthmic spondylolisthesis. To determine the long-term effect of PLIF using psterior movable segment, we analysed the results of follow-up radiologic changes and surgical outcome retrospectively Patients and Method : During the past 11 years(1989. 1.-1999. 9.), 148 patients with symptomatic lumbar spondylolisthesis were managed at our department and the clinical wants were throughly recieved and final outcome is determined at last follow up. PLIF using antogenous bone(posterior movable segment, iliac bone and rib) were performed in 106 case. Results : After an average follow-up period of 33 months(range ; 15-58 months), the results were excellent in 66 cases, good in 37 cases, fair in 2 cases and poor in 1 cases. And the satisfactory results were 103 cases(98.2%) in PLIF,. Conclusion : In conclusion, patients who underwent PLIF with autologous bone graft had good clinical and radiological outcomes without significant neurological complications.

• Journal of Korean Foot and Ankle Society
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• v.27 no.2
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• pp.75-78
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• 2023

During bone tumor resection, many cases require medial malleolar osteotomy to achieve adequate access to the operative field. Various osteotomy methods have been developed to address this issue, including oblique, transverse, reverse V-shape, and step-cut osteotomies. However, medial malleolar osteotomy has several drawbacks, such as the excessive disruption of the joint surface, unstable screw fixation when fixing the medial malleolus, and iatrogenic medial ankle joint arthritis due to articular displacement during the reduction of the osteotomy site. In addition, there is a possibility of injury to the posterior tibial artery, tibial nerve, or posterior tibialis tendon if the osteotomy range is too aggressive. Therefore, the authors propose a new osteotomy method, which has shown promising clinical results, namely, partial posterior medial malleolar osteotomy. This method minimizes articular involvement and provides adequate access to the operative field during talar body bone tumor resection.

• The Journal of Advanced Prosthodontics
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• v.6 no.5
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• pp.325-332
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• 2014

PURPOSE. The aim of this review was to analyze the evaluation criteria on mandibular implant overdentures through a systematic review and suggest standardized evaluation criteria. MATERIALS AND METHODS. A systematic literature search was conducted by PubMed search strategy and hand-searching of relevant journals from included studies considering inclusion and exclusion criteria. Randomized clinical trials (RCT) and clinical trial studies comparing attachment systems on mandibular implant overdentures until December, 2011 were selected. Twenty nine studies were finally selected and the data about evaluation methods were collected. RESULTS. Evaluation criteria could be classified into 4 groups (implant survival, peri-implant tissue evaluation, prosthetic evaluation, and patient satisfaction). Among 29 studies, 21 studies presented implant survival rate, while any studies reporting implant failure did not present cumulative implant survival rate. Seventeen studies evaluating peri-implant tissue status presented following items as evaluation criteria; marginal bone level (14), plaque Index (13), probing depth (8), bleeding index (8), attachment gingiva level (8), gingival index (6), amount of keratinized gingiva (1). Eighteen studies evaluating prosthetic maintenance and complication also presented following items as evaluation criteria; loose matrix (17), female detachment (15), denture fracture (15), denture relining (14), abutment fracture (14), abutment screw loosening (11), and occlusal adjustment (9). Atypical questionnaire (9), Visual analog scales (VAS) (4), and Oral Health Impact Profile (OHIP) (1) were used as the format of criteria to evaluate patients satisfaction in 14 studies. CONCLUSION. For evaluation of implant overdenture, it is necessary to include cumulative survival rate for implant evaluation. It is suggested that peri-implant tissue evaluation criteria include marginal bone level, plaque index, bleeding index, probing depth, and attached gingiva level. It is also suggested that prosthetic evaluation criteria include loose matrix, female detachment, denture fracture, denture relining, abutment fracture, abutment screw loosening, and occlusal adjustment. Finally standardized criteria like OHIP-EDENT or VAS are required for patient satisfaction.