Biocompatibility and Efficiency of Biodegradable Magnesium-Based Plates and Screws in the Mandible Fracture Model of Beagles

Background Trauma involving bone are very common and occur six million bone fracture each year in the United States. These fractures are caused by a variety of causes such as birth defect, osteoporosis, osteomyelitis, MRONJ (Medication related osteonecrosis of the jaw) and, most commonly, trauma. As the population ages and the number of medically compromised patients increases, the rate of pathologic bone fracture is expected to be increased in the future. For this reason, fracture treatment remains an important clinical focus in bone tissue engineering. Fracture treatments often require internal fixation. Plates and screws are used for alignment and stabilization of bone fragments. Largely, two kind of internal bone fixation devices have been used such as metallic and polymeric substances. Internal anchors made of permanent metal are associated with numerous long-term complications and may require removal. Polymeric materials are biodegradable and need not be removed, but are known to have poorer mechanical quality than metals. Unlike permanent metals and resorbable polymers, degradable magnesium alloys can provide an ideal balance of degradation and strength. Recent investigations of magnesium alloys in vivo have highlighted their potential as bone fixation materials. Purpose A biodegradable magnesium alloy system has been developed as a substitute for conventional plates and screws made of titanium or absorbable polymer. However, previous studies were limited to small animal experiments using screws or wires. In this study, human standard-sized degradable magnesium devices were evaluated by using the mandible fracture model of beagles. Device degradation, fracture healing, and new bone formation were assessed. Method and Materials The biodegradable magnesium alloy plate products are evaluated using biological safety / efficacy in large animals. Among large animals, beagle, in which the masticatory and oral conditions are similar to those of humans, is routinely selected as an experiment related to CMF implants and other dental materials. The hydrogen gas generation and decomposition behavior around the plates were evaluated for the fracture site on the mandibular right mandible. Micro CT images were performed 5 times at 4 weeks interval (1, 4, 8, 12, 16 weeks) immediately after implantation. Bone and tissue volumes were calculated using CT analyzing software. Histology was performed after sacrifice. Local response and biocompatibility were evaluated. Result and Discussion The biodegradable magnesium plates used in this study were found to be a positive result in histological and pre-clinical evaluation after 16 weeks of CT and after sacrifice. Particularly, additional bone formation in the surgery site was found when it compared to the control site, and hydrogen gas pocket formation as a result of plate decomposition was observed in one animal. However, all dogs underwent normal healing process. Further study is recommended to confirm that bone deposition is more prevalent in comparison with the control site before the prototype is applied to humans, and how to control hydrogen production at the early stage of surgery.Docto

치과근관치료 의사결정지원체계에 있어서의 치의학 온톨로지의 사용

학위논문 (석사)-- 서울대학교 대학원 : 치의학과, 2012. 2. 김홍기.1. 목 적 치수염과 근관치료의 연관성을 밝히고 환자의 임상적반응과 조건에 따라 치료계획을 제시하는 의사결정지원체계의 틀을 마련하는 것은 의미가 있을 것이라 생각되므로 치의학 온톨로지를 치과근관치료의 의사결정지원체계에 적용시켜보고 앞으로의 온톨로지 연구의 나아갈 길을 모색해 볼 것이다. 2. 방 법 온톨로지를 발전시키는데 있어서 적절한 공식성을 지닌 온톨로지를 채택하는것은 매우 중요한 요소이다. KIF, Ontolingua, Semantic Net, Frames 등의 다양한 온톨로지가 개발되었다. 한편 웹영역에서는 the Web-based Ontology Language (OWL)가 대표적인 온톨로지로 부각되었다. 또한 OWL은 의학적인 영역에서 Diseases, Objectives, Anatomy, Treatments 등을 잡아내고, 보여주는 데에 이용되어 왔다. OWL은 Descriptive Logic, 묘사적인 논리를 갖고 있다. 이것은 현재 사용되고 있는 온톨로지 중 가장 선호되는 논리이다. 묘사논리는 현재까지 가장 많이 행해져 왔고, Protégé 와 같은 좋은 편집도구를 갖고 있다. 그리고 이것은 검사하고 추론하는데 있어서 자체 완결성을 갖고 있어서 개념을 투사하는데 모자람이 없다. 그리하여 기존의 연구에서는 OWL2가 공식성을 갖고 사용되었다. OWL 2-based Manchester DL syntax4 가 수복치료학의 온톨로지중 우식치료를 위해 사용되었다. 여기에서도 OWL2 Manchester syntax 에 기반하여서 진단과정을 언급할 것이다. [1] 한편, 본 논문에서는 치수에 생긴 병적 변화를 언급하는데 있어서 Smulson and Sieraski (Weine textbook)혹은 Walton and Torabinejad등의 분류가 있지만 다음과 같은 서울대학교 치의학대학원의 분류를 따를 것이다. 3. 결 과 1) 서울대학교 치의학대학원의 치수병변 분류 * 염증성 변화 (Inflammation) 1. 치수충혈 (Pulp hyperemia) 2. 치수염 (Pulpitis) a) 급성치수염 (Acute Pulpitis) b) 만성궤양성치수염 (Chronic ulcerative pulpitis) c) 만성증식성치수염 (Chronic hyperplastic pulpitis) 3. 치수괴사 (Pulp necrosis) * 퇴행성 변화 (Degeneration) 1. 치수의 변성 (Pulp Degeneration) a) 석회화 변성 (Calcific Degeneration) b) 섬유화 변성 (Fibrous Degeneration) c) 변성위축 (Atrophic Degeneration) d) 내(부) 흡수 (Internal Resorption) 이와같은 학술적인 분류는 다음과 같은 온톨로지로 표현한다. Class: Inflammation SubclassOf: Disease Class: Pulp_Hyperemia SubclassOf: Inflammation Class: Pulpitis SubclassOf: Inflammation Class: Acute_Pulpitis SubclassOf: Pulpitis Class: Chronic_Ulcerative_Pulpitis SubclassOf: Pulpitis Class: Chronic_Hyperplastic_Pulpitis SubclassOf: Pulpitis Class: Pulp_Necrosis SubclassOf: Inflammation Class: Degeneration SubclassOf: Disease Class: Calcific_Degeneration SubclassOf: Degeneration Class: Fibrous_Degeneration SubclassOf: Degeneration Class: Atropic_Degeneration SubclassOf: Degeneration Class: Internal_Resorption SubclassOf: Degeneration 각각의 질환에 대한 판단 논리와 그에 해당하는 온톨로지가 본 논문에 존재한다.Maste

스포츠 상황에서 자기조절 초점과 목표추구 행동간의 관계

학위논문(박사)--서울대학교 대학원 :체육교육과,2001.Docto

The Development and Validation of Scales Assessing Middle School Students' Achievement Goal Orientation

Traditionally, although theorists have described achievement motivation in terms of approach and avoidance tendencies, goal orientation, research has focused primarily on two approach goals (Dweck, 1986; Nicholls, 1984; Ames, 1987) : the learning or task goal to develop and improve one's ability, and the performance or ego goal to demonstrate ones ability through the comparison with other people. Recently, three-dimensional achievement goal theory including the goal to develop ability (learning goal orientation), the goal to demonstrate ability (performance-approach goal orientation) and the goal to avoid the demonstration of lack of ability (performance-avoid goal orientation) has emerged as a new direction in motivational research (Button, Mathieu, & Zajac, 1996; Elliot, 1994; Elliot & Harackiewicz, 1996; Vandewalle, 1997; Middleton & Midgley, 1997; Elliot & Church, 1997; Skaalvik, 1997; Midgley, Kaplan, Middleton, Maehr, Urdan, Anderman & Roeser ; 1998). Accordingly, a scale to assess the goal of avoiding the demonstration of lack of ability (performance-avoidance goal) was included with scales assessing approach goals in a survey given to students in the middle school. The results of studies conducted with three different samples of 1,005 middle school students were used to describe the validity and reliability of the scale. The content-related evidence of validity by means of 5 experts, the construct-related evidence of validity through exploratory factor analysis and confirmatory factor analysis, and the criterion-related evidence of validity included into concurrent validity with TEOSQ, intrinsic motivation, and the implicit belief of intelligence and prediction validity with the score of physical education all supported the conclusion that the instrument operationalized the theorized three-dimensional construct.본 연구는 1999년도 서울대학교 사범대학 발전기금의 지원에 의해서 연구됨