• 대한치과의사협회지
• /
• 제48권10호
• /
• pp.754-761
• /
• 2010

Horizontal root fractures are defined as those that involve cementum, dentin and pulp, comprising from 0.5 to 7% of injuries in permanent dentition on dental trauma. Diagnosis is made through clinical findings and radiographic exams, the latter frequently being limited by the position of the fracture line. Treatment varies according to the displacement of crown portion and vitality of the fragments. Authors describe clinical cases of maxillary right central incisor with horizontal root fractures in dental clinic, Jeju National University Hospital.

• Journal of Periodontal and Implant Science
• /
• 제38권1호
• /
• pp.15-22
• /
• 2008

Purpose: The attachment level is strongly associated with tooth loss and provides useful information on patterns of destruction of the periodontium. The presence of horizontal attachment loss would not be detected in clinical measurement. Therefore, the purpose of the present study was to estimate the patterns of periodontal destruction based on the attachment area and horizontal attachment loss in extracted teeth due to severe periodontitis. Materials and Methods: 307 teeth satisfied the criteria for assessment. An indirect method, based on digital images obtained from a digital camera and an image analysis program, was used to calculate the area of root surface and attachment loss and the extent of horizontal attachment loss. The data were analysed using SPSS. Results: No statistically significant differences among root surfaces were observed in anterior teeth on the loss of attachment area. However, in posterior teeth statistically significant differences in palatal surfaces of maxillary and mandibular premolar and molar surfaces compared with buccal surfaces were observed. Horizontal attachment loss was observed in 21.5% of the teeth examined. Frequency of horizontal attachment loss was highest in the maxillary first premolar (34.8%), followed by the maxillary second premolar (27.3%) and maxillary canine (25%). The mean length of horizontal attachment loss was 1.5mm. Conclusion: More meticulous examination will be needed of the palatal surfaces of maxillary and mandibular premolar and molar teeth. The percentage of teeth with horizontal attachment loss greater than 2.1 mm was 5.2%. Considering the length of curette blades, about 5.2% of teeth were not properly debrided. Therefore, Additional supportive therapy such as local drug delivery has to be considered in treatment of the first maxillary, second premolar and canine due to the high prevalence of horizontal attachment loss.

• 한국산림과학회지
• /
• 제89권5호
• /
• pp.677-684
• /
• 2000

본 연구는 토양 특성이 다른 30-40년생 독일가문비나무(Picea abies [L.] KARST) 임분에서 토양 깊이에 따른 뿌리구조 분석을 통하여 뿌리 발달의 차이점과 토양 상태의 상호관계 및 외부 형태적 특징 그리고 기계적 물리적 안정성에 대한 적응범위를 밝히고자 실시하였다. 조사된 3개 임분에 있어서 독일가문비나무의 뿌리구조는 다양한 형태로 관찰되었는데, Eberg$\ddot{o}$tzen 임분은 뿌리수가 많고 가늘며 토양 깊이까지 발달한 뿌리구조를 보였으며, Barbis 임분은 Eberg$\ddot{o}$tzen 임분에 비하여 그 수가 적으나 굵고 깊이까지 자라는 뿌리구조를 나타내었다. 그리고 Weidenbrunnen 임분은 반 수직 뿌리와 편평/접시형 뿌리구조를 나타내었다. 뿌리의 수는 Eberg$\ddot{o}$tzen 임분이 74개로 가장 많은 뿌리 수를 보여주었으며, Barbis 임분은 33개, Weidenbrunnen 임분은 57개이었다. Eberg$\ddot{o}$tzen 임분은 수직뿌리에서 평균 57개로 Barbis 임분이 21개이고, Weidenbrunnen 임분 36개에 비하여 월등히 많은 뿌리의 수를 나타내었다. 뿌리의 길이는 Weidenbrunnen 염분이 전체 뿌리길이가 다른 두 임분에 비하여 길게 나타났으며, 수형뿌리의 길이는 수직뿌리에 비하여 그 값이 107m로 매우 큰 값을 나타내었다. 수직뿌리에 대한 수평뿌리의 비는 Eberg$\ddot{o}$tzen 임분이 다른 두 임분(0.5)에 비하여 그 값이 1.2로 높게 나타났다. 전체 뿌리무게는 다른 두 임분에 비하여 Weidenbrunnen 임분이 매우 높은 값을 보여 주였으며, 수명뿌리에 대한 수직뿌리의 비는 0.16으로 다른 두 임분(0.40)에 비해 매우 낮은 값을 나타내었다. 본 연구의 독일가문비나무 임분에서 나타난 뿌리 발달의 현저한 차이점은 토양의 기계적 물리적 요인보다는 토양 산성화와 같은 화학적인 요인으로 인하여 정상적인 뿌리의 발달이 장애를 받아 수직뿌리생장이 저하되고 수분과 영양분의 스트레스로 언하여 상대적으로 수평뿌리가 발달된 결과로 사료된다.

• Journal of Periodontal and Implant Science
• /
• 제45권5호
• /
• pp.184-189
• /
• 2015

Purpose: The purpose of the present study was to evaluate the effect of root planing on the reduction of probing pocket depth and the gain of clinical attachment depending on the pattern of bone resorption (vertical versus horizontal bone loss) in the interproximal aspect of premolar teeth that showed an initial probing pocket depth of 4-6 mm. Methods: In this study, we analyzed 68 teeth (15 from the maxilla and 53 from the mandible) from 32 patients with chronic periodontitis (17 men and 15 women; mean age, 53.6 years). The probing pocket depth and clinical attachment level at all six sites around each tooth were recorded before treatment to establish a baseline value, and then three months and six months after root planing. Results: The reduction in interdental pocket depth was 1.1 mm in teeth that experienced horizontal bone loss and 0.7 mm in teeth that experienced vertical bone loss. Interdental attachment was increased by 1.0 mm in teeth with horizontal bone loss and by 0.7 mm in teeth with vertical bone loss. The reduction of probing pocket depth and the gain of clinical attachment occurred regardless of defect patterns three and six months after root planing. Conclusions: The reduction of pocket depth and gain in the clinical attachment level were significantly larger in horizontally patterned interproximal bone defects than in vertical bone defects.

• 대한치과보철학회지
• /
• 제44권5호
• /
• pp.561-573
• /
• 2006

Statement of the problem: In cases of low bone level in maxilla followed by extraction due to severe periodontitis or enlarged maxillary sinus, crown-root ratio of implant prosthesis will increase. The prognosis of these cases is not good as expected. Purpose : The purpose is to compare stress distribution due to crown-root ratio and effect of splinting between two implants in maxillary molar area under different loads Material and methods: Using ITI($4.1{\times}10$ mm) implant. two finite element models were made(model S: two parallel implants, model A: one of two is 20 degree inclined). Each model was designed in different crown-root ratio(0.7:1, 1:1, 1.25:1) and set cement type gold crown to make it splinted or non-splinted clinical situations. After that, 300 N force was loaded to each model in four ways.(load 1 : middle of occlusal table, load 2 : middle of buccal cusp, load 3 : middle of lingual cusp, load 4 : horizontal load to middle of buccal cusp), and stress distribution was analyzed. Results: On all occasions, stress was concentrated on neck of implant near cortical bone. In the case of inclined implant, stress was increased compared with parallel implants. Under load 1, 2, 3, stress was not increased even when crown-root ratio increases, but under load 4, when crown-root ratio increases, stress also increased. And more stress was concentrated under load 1 than load 2, 3. When crown-root ratio was same, stress under load 1, 2, 3 decreased when splinting, but under load 4, stress did not really decrease. Conclusion: Under vertical load, stress distribution related to crown-root ratio did not change. But under horizontal load, stress increased as crown-root ratio increases. Under vertical load, splinting decreased stress but under horizontal load, effect of splinting was decreased as condition of implant changes for the worse such as increase of crown-root ratio, inclined implant.

• 농업생명과학연구
• /
• 제45권5호
• /
• pp.33-39
• /
• 2011

본 연구는 강원지역 1영급 금강소나무를 대상으로 천연임분과 인공임분간의 직경별 뿌리의 분포 특성을 알아보기 위해 실시하였다. 직경별 뿌리분포는 두 임분 모두 0.5-2.0 mm 직경급의 뿌리가 가장 많았고, 10.0-20.0 mm 직경급의 뿌리가 가장 적었다. 두 임분간 직경별 뿌리발달에서 5.0 mm 이하의 직경급은 인공임분이 천연임분보다 우수하였지만, 5.0 mm 이상의 직경급 발달은 천연임분이 더 우수하였다. 토양층위별 뿌리의 직경별 발달은 천연임분이 인공임분보다 다양한 토양층위에 고르게 분포하였으며, 인공임분은 5.0 mm 이하의 직경급이 토심 10 cm, 토양 수평층위 20 cm 범위 내에 편중되어 발달하였다. 따라서 임분 성립방법의 차이는 뿌리발달의 현저한 구조적 차이를 나타낼 수 있으며, 이러한 결과는 인공조림시 올바른 식재방법과 조림지침을 제공하는데 중요한 기초자료로 사용될 수 있을 것이다.

• 대한치과보존학회:학술대회논문집
• /
• 대한치과보존학회 2004년도 춘계 학술대회 (제121회) 초록집
• /
• pp.312-314
• /
• 2004

• 대한치과보존학회:학술대회논문집
• /
• 대한치과보존학회 2002년도 춘계학술대회
• /
• pp.344-345
• /
• 2002

• Restorative Dentistry and Endodontics
• /
• 제19권2호
• /
• pp.549-567
• /
• 1994

Restoration of severly damaged teeth after endodontic treatment had been an interest to many dentists, and it is a fact that there have been lots of studies about it. In these days, although we have used Para-Post, pins, threaded steel post, cast gold post and core, and so on, as a method of restoration frequently, it has been in controversy with the influence of them on the teeth and surrounding periodontal tissue. In this study, we assume that the crown of the upper incisor have severly damaged, so, after the root canal therapy, 4 types of restoration had been carried out; 1) coronal-radicular amalgam restoration, 2) after setting up the Para-Post, restore with composite resin core only, 3) after setting up the Para-Post; restore with amalgam core, then cover with the PPM crown 4) after setting up the Para-Post, restore with composite core, then cover with the PPM crown. After restoration, in order to observe the concentration of stress at internal portion of the teeth and the sourrounding periodontal tissue, developing a 2-dimensional finite element model of labiopalatal section, then loading forces from 3 direction - direction of 45 degrees from lingual side near the incisal edge, horizontal direction from labial height of contour, vertical direction at the incisal edge-were applied. The analyzed results were as follows: 1. Stress of the normal central incisor was concentrated on the dentin aroundpulp chamber, labiocervical portion of a tooth and root apex, but with the alveolar bone, in the case of load from the direction of 45 degrees from lingual side near the incisal edge showed remarkable concentration of stress: 2. Coronal-radicular amalgam technique -showed less concentration of stress on the root and surrounding periodontal tissue than the restoration with the Para-Post. 3. The von Mises equivalent stress on the Para-Post showed maximum value at root-core junction rather than both ends and model with PPM restoration with amalgam core showed the least concentration of stress. Only the force from horizontal direction showed large shear stress on internal portion of the root, root apex and alveolar bone. 4. PPM crown with composite core rarely showed the concentration of stress on root and periodontal tissue. 5. As for alveolar bone, remarkable shear stress was concentrated on labial and palatal side by horizontal load.

• Journal of Welding and Joining
• /
• 제21권3호
• /
• pp.46-50
• /
• 2003

The horizontal fillet joint is one of the most important weld joints in the shipbuilding industry. High-speed rotating arc welding, which can increase the leg length, is an effective way to improve the weld productivity and quality for the horizontal fillet welding. Based on the Taguchi method, the effects of welding parameters on bead characteristics - leg length, asymmetry, undercut, overlap - are investigated fur high-speed welding process. As a result, the adequate welding parameters are selected for the required leg length, symmetric bead and no undercut. Besides, considerably consistent leg length is observed for the horizontal fillet welding with gap variation up to 3mm.