• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.735-741
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• 2018

In this paper, the surface recession of ablative materials was quantitatively analyzed using a high-speed camera and a three-dimensional profilometer. The ablation tests of the graphite and carbon/phenolic composite samples were performed using a 0.4 MW arc-heated wind tunnel for simulating the atmospheric re-entry environment. The real-time images during the ablation test were captured by the high-speed camera, and analyzed to calculate the surface recession and recession rate. Also, the surface data of samples were obtained using a three-dimensional profilometer, and the surface recession was precisely calculated from the difference of height between the surface data before and after the test. It is effective to complement the two measurement results in the comprehensive analysis of surface recession phenomena.

• Journal of Periodontal and Implant Science
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• v.31 no.1
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• pp.243-258
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• 2001

Gingival recession is exposure of the root surface with apical shift in the position of gingiva. The incidence of gingival recession is 8% in children and 100% after the age of 50. Recession tends to be found in patients with healthy gingiva, but more frequentely found in patients with periodontal disease, and it often causes mucogingival defects. Buccal surface of premolar is the area not only for severe gingival recession and cervical abrasion, but also the area of numbers of buccal frenum and less keratinized gingiva. Threrfore, the goal of this study was to observe the patients with periodontitis and examine whether there are clinical relations between gingival recession and cervical abrasion of premolar and other factors related with the condition of periodontal health. Generally healthy 218 patients who had periodontitis, aged between 18 and 78, were examined for depth of periodontal poket, width of attached gingival, gingival recession, cervical abrasion, and frenum of mid-buccal surface of premolar at the Department of Periodontics in Dankook University Dental Hospital and following is the result. 1. The average gingival recession and cervical abrasion of premolar with periodontal disease was 0.76mm and 0.29mm and each has 43% and 14% of incidence. Also the width of attached gingiva of mid-buccal surface was 1.77mm. the average periodontal pocket depth is 2.0mm and 47% of frequently seen was narrow single shaped frenum, and the interdistance of the frenum was mostly over 4mm. 2. With statistical significance(P<0.05), the incidence of gingival recession increased with age and was related much more with female than male, the first premolar than the second premolar, and with narrow attached gingiva and frenum. 3. With statistical significance(p<0.05), the incidence of cervical abrasion increased with age and was related with the area of the first premolar and narrow attached gingiva, but the sexual and frenum differences were not statistically significant (p>0.05). 4. The severity of gingival recession increased with age and was more related with female than male, the first premolar than the second premolar. And the area of narrow attached gingiva and frenum showed more gingival recession and the distance of frenum was more highly related than shape, and they were statistically significant (p<0.05). 5. With statistical significance(p<0.05), the severity of cervical abrasion increase with age and was observed at the first premolar and narrow attached gingiva. But the sexual and frenum differences were not statistically significant (p>0.05).

• Korean Journal of Veterinary Research
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• v.38 no.4
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• pp.936-945
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• 1998

This study was performed to investigate the best surgical technique for normal stifle mobility by comparison with clinical signs and histopathological changes of articular cartilage after femoral trochleoplasty, trochlear chondroplasty and trochlear wedge recession. Twelve small mixed dogs who had grade I or II medial patellar luxation were used. The days that the dog had partial and full weight bearing were checked and histopathological changes 49 and 90 days after surgery were observed. The dogs had partial weight bearing in 3~6 days postoperatively and full weight bearing in 20~24 days. After femoral trochlepoplasty, the articular surface was irregular and rough, but smooth after trochlear chondroplasty and trochlear wedge recession. Histopathologic examination performed on the 49th and 90th days after femoral trochleoplasty revealed that articular surface was occupied by fibrocartilage but the hyaline cartilages are preserved after trochlear chondroplasty and trochlear wedge recession. In trochlear wedge recession, the wedges of all cases were firmly attached to underlying subchondral bone which were indicating complete healing. The results of this study suggested that the trochlear wedge recession was the best chondroplasty for correcting patellar luxation.

• Journal of Periodontal and Implant Science
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• v.36 no.1
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• pp.51-60
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• 2006

Gingival recession is clinically manifested by an apical displacement of the gingival tissue and dentin hypersensitivity is often used to describe a painful condition in which exposed dentin is unduly sensitive to intraoral stimuli. The objects of this study were primarily to investigate the prevalence and distribution of gingival recession and hypersensitivity and secondarily to determine whether a relationship exists between gingival recession and hypersensitivity. The study population was 195 patients (102 males, 93 females) who were attended the department of periodontology, Pusan National University Hospital. 189 patients exhibited gingival recession at least more than 1 tooth, the prevalence was 96.9%. The maxillary and mandibular first premolar and mandibular incisors had the highest prevalence. The majority of patients (139 patients, 71.3%) were diagnosed as having dentin hypersensitivity. Dentin hypersensitivity was determined to 3 seconds application of cold air to the exposed root surface after isolating the test tooth and was commonest in maxillary and mandibular first premolars and mandibular incisors. Relationship between recession and hypersensitivity was analyzed using chi-square test (p=0.05), significant relation (p=0.000) was existed. Gingival recession was more severe, the prevalence of hypersensitivity was higher.

• The Journal of the Korean dental association
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• v.55 no.7
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• pp.450-456
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• 2017

The purpose of this case report is to present a case of free gingival graft for treatment of mandibular incisor labial gingival recession relapsed after laterally positioned flap surgery. A 22 year-old female patient with discomfort and labial gingival recession on left mandibular central incisor was treated. The patient had been treated root coverage on same site by laterally positioned flap surgery, but treated site had relapsed in one month. Exposed root surface was covered by free gingiva from left palatal area. Although gingival color did not completely match with adjacent gingiva, more than 5mm keratinized gingiva was attained. The patient showed no further recurring pain and recession on gingiva after 5 months from the surgery. In conclusion, the root coverage with gain of keratinized gingiva could be achieved through free gingival graft from palate on relapsed gingival recession.

• Journal of Periodontal and Implant Science
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• v.25 no.1
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• pp.121-132
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• 1995

Patients, who have gingival recession and complain of root sensitivity, or esthetic concerns, are candidates for root coverage. When free gingival grafting is used for complete root corverage, the results may not be entirely predictible unless the recession is shallow and narrow because a free gingival graft depends on collateral circulation from the lateral and apical parts of the recipient bed to survive over the avascular root. Various pedicle graft techniques can produce more esthetic results, but these procedures are only indicated when adequate donor tissues are available adjacent to the defect. This case report presents three cases for root coverage using the various connective tissue graft techniques. In the first case(Class III & IV), subepithelial connective tissue grafting was done and resulted in gingival coverage on the two-thirds of exposed root surface and blended with the adjacent tissue in color and texture. In the second case(Class I), connective tissue and partial thickness double pedicle graft resulted in complete coverage of denuded root surface. In the third case(Class I), recession was treated by supraperiosteal envelope technique. The root surface was covered completely and esthetically. Finally, the esthetics in both colors and tissue contours were acceptable to patients in all cases by the connective tissue grafting. However, in the case of the reduced interdental bone, the denuded root surfaces were hardly covered completely.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1048-1053
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• 2015

Ablative materials in a thermal protection system for atmospheric re-entry suffers from the most severe heat fluxes and temperatures, which induces surface recession in the thickness direction. In this paper, a 0.4MW arc-heated wind tunnel is operated to test for ablative materials, and a non-contact three-dimensional surface measuring system is used to evaluate the different surface characteristics of them. In particular, by postprocessing the three-dimensional image data, the surface roughness and recession of ablative materials can be calculated before and after the wind tunnel test. Moreover, the surface properties are analyzed quantitatively by comparing volume and mass losses of the test specimens.

• The Journal of the Korean dental association
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• v.55 no.3
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• pp.230-239
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• 2017

Root coverage can be an efficacious treatment not only in aspect of dental symptoms like root caries and hypersensitivity, but also in aspect of esthetic problem. There are several predictable methods for gaining a connective tissue attachment to an exposed root surface. Among them, this case report will deal with three cases using enamel matrix derivative and connective tissue graft to recover esthetic and physiological periodontal environment and its form. This case report deals with three patients with gingival recession which has occurred by different causes. They were treated with de-epithelialized graft accompanied by application of enamel matrix derivative. 6-12 months later, all three patients showed considerable root coverage and clinically stable condition of healing. In conclusion, within the limitation of this study, de-epithelialized connective tissue graft accompanied by application of enamel matrix derivative shows stable and clinical acceptable results in aspect of root coverage.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.8
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• pp.597-604
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• 2013

A coupled thermomechanical analysis of composite structures in pyrolysis and ablation environments is performed. The pyrolysis and ablation models include the effects of mass loss, pore gas diffusion, endothermic reaction energy, surface recession, etc. The thermal and structural analysis interface is based upon a staggered coupling algorithm by using a commercial finite element code. The characteristics of the proposed method are investigated through numerical experiments with carbon/phenolic composites. The numerical studies are carried out to examine the surface recession rate by chemical and mechanical ablation. In addition, the effects of shrinkage or intumescence during the pyrolysis process are shown.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.231-236
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• 2008

Purpose: The treatment of gingival recessions is needed to reduce root sensitivity and improve esthetical satisfaction. Several surgical techniques have been proposed to achieve these goals. The use of connective tissue grafts has made esthetic root coverage a predictable procedure. Numerous clinical studies have represented that using connective tissue grafts to cover exposed root surface showed high success rates. This is a case report which demonstrates the technique to obtain root coverage of a buccal recession defect. Materials and Methods: A 35-year-old patient with a high level of oral hygiene was selected for the study. This patient had one Class I Miller recession defect in the mandible. A coronally advanced flap in combination with the connective tissue graft was chosen for the treatment. After surgery, the patient was told to visit the hospital once a week for his oral management and professional prophylaxis. The depth of initial recession was 4.0 mm. Result: After three months, it reduced to 0.0 mm, and the average recession reduction was 4.0 mm. The average root coverage was 100%. Conclusion: The connective tissue graft is both effective and predictable way to produce root coverage in increasing the width of CAL and KT of various adjacent gingival recessions.