• Restorative Dentistry and Endodontics
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• 제23권2호
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• pp.656-669
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• 1998

Hydrogen peroxide at high concentration during walking bleaching may cause damage to the tooth structure and to the surrounding periodontal tissues and may develop external root resorption. Clinically, It is so important to find a method of prevention or minimization of these complications. The efficacy of various chamber-irrigating agents to eliminate residual hydrogen peroxide after walking bleaching was examined and compared with water rinse in this study. Extracted human 46 premolars without any cementoenamel junction defects were treated endodontically and based with IRM to 1 mm below CEJ and totally bleached 3 times for each tooth with 30% hydrogen peroxide and sodium perborate. Upon completion of the 3rd walking bleaching procedure, the cervical portion and pulp chamber of each group of teeth were irrigated with catalase, 70% ethylalcohol, acetone, and distilled water. And then, a radicular hydrogen peroxide penetration was measured with spectrophotometer immediately after each bleaching and following treatment with each chamber-irrigating agents, and the significance of their eliminating efficacy of residual hydrogen peroxide was analyzed by Kruskal-Wallis test. The results were obtained as follows. 1. Cervical root penetration of hydrogen peroxide was increased as the bleaching procedure was repeated(P<.01). 2. The most effective irrigant that removed residual hydrogen peroxide was the catalase, and the least effective one was water rinsing (P<.01).; there was no significant difference between the acetone and ethanol group. 3. The Irrigation with antioxidant enzyme or water-displacement solutions can eliminate residual oxygen radicals from the pulp chamber effectively after walking bleaching. So, these agents can reduce adverse effects such as cervical external resorption and periapical inflammation and prevent residual $O_2$ from impeding composite resin polymerization, thus increase the bonding strength of composite resin. This, in turn reduces microleakage and discoloration of the esthetic restoration, extending its service-life.

• 대한소아치과학회지
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• 제31권4호
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• pp.729-733
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• 2004

완전 탈구된 치아의 치료 목적은 치주인대 세포의 손상과 치수 조직의 감염에 의한 염증 반응을 예방하거나 최소화하는 것이다. 치주인대 세포의 생활력은 완전 탈구된 치아의 예후에 있어 중요한 요소인데 치주인대 세포가 생활력을 유지하는 경우 재식시 재부착을 하게 되어 최소한의 염증반응 후 신생 백악질로 회복되지만, 생활력을 상실하게 되면 심한 염증반응을 야기하게 되어 광범위한 치근 흡수와 유착이 나타나게 된다. 치근이 유착되면 특히 성장하는 어린이일 경우 치조돌기의 성장을 방해하여 저위교합을 유발하게 된다. 또한 광범위한 치근 흡수나 유착으로 인한 치아의 조기 상실은 치조골의 흡수와 인접치의 지속적인 이동을 야기하여 기능적, 심미적인 문제를 발생케 한다. 본 증례는 상악 우측 중절치의 완전 탈구 후 재식한 후 항생제 투여 및 장기간의 수산화 칼슘 적용을 통해 9년에 걸쳐 기능적, 심미적으로 양호한 결과를 얻었기에 이에 보고하는 바이다.

• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.250-260
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• 1995

Bases have been used in order to prevent the leakage of bleachingagents through dentinal tubules in bleached teeth. But the proximal surfaces where the actual resorption takes place havenot been protected. The purpose of this study was to compare the conventional basing method with the basing of the labial and two proximal surfaces to the cementoenamel junction. The bases were placed after conventional root canal treatment. Group I: 2mm thickness bases were placed to the level of labial cementoenamel junction line. Group II : 2mm thickness bases were placed to the level of all c-e J lines including cervical area. Control : No bases were placed. After placement of sodium perborate and 30% hydrogen peroxide mixtureinto the teeth, the changes of pH were measured. The results were as follows. 1. Group II showed smaller leakage of bleaching agents and was statistically significant difference compared to Group I.(p<0.05) 2. Group I showed no statistically significant difference compared to the control group. (p>0.05) 3. There were no significant among the upper and lower teeth groups in each group and between the groups.(p>0.05). According to the above results, it was considered that basing of the labial and proximal surfaces to the cementoenamel junction can reduce the leakage of bleaching agents during bleaching procedure of pulplessteeth.

• 대한소아치과학회지
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• 제24권4호
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• pp.727-733
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• 1997

Autotransplantation is a procedure which transplants teeth from the original position to other positions in the same individual. It is classified surgical reposition by intraalveolar autotransplantation and transalveolar autotransplantation. The prognosis for successful autotransplantation is dependent on a number of factors such as root development, surgical technique, patient's age, endodontic treatment, time and type of splinting, preservation of periodontal ligament and storage medium. The most important factor is preservation of periodontal ligament. The cause of the failure of transplantation include damage of the transplant during removal from deep palatal malposition, poor regeneration of the bone around the transplant and chronic periodontal infection. In case I, Impacted maxillary canine for which surgical exposure and orthodontic treatment was impossisle was transplanted. After 2 weeks, It showed periapical radiolucency and external root resorption. So, endodontic treatment was done. One year later, permanent filling was done with gutta percha. In case II, Transpositioned maxillary central incisor was transplanted after extraction of impacted mesiodens. Pulp vitality was maintained during 5 months without other clinical symptons.

• Restorative Dentistry and Endodontics
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• 제38권1호
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• pp.26-30
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• 2013

Objectives: The aim of this study was to investigate the relationship between the apical foramen morphology and the length of merged canal at the apex in type II root canal system. Materials and Methods: This study included intact extracted maxillary and mandibular human premolars (n = 20) with fully formed roots without any visible signs of external resorption. The root segments were obtained by removing the crown 1 mm beneath the cementum-enamel junction (CEJ) using a rotary diamond disk. The distance between the file tip and merged point of joining two canals was defined as Lj. The roots were carefully sectioned at 1 mm from the apex by a slow-speed water-cooled diamond saw. All cross sections were examined under the microscope at ${\times}50$ magnification and photographed to estimate the shape of the apical foramen. The longest and the shortest diameter of apical foramen was measured using ImageJ program (1.44p, National Institutes of Health). Correlation coefficient was calculated to identify the link between Lj and the apical foramen shape by Pearson's correlation. Results: The average value of Lj was 3.74 mm. The average of proportion (P), estimated by dividing the longest diameter into the shortest diameter of the apical foramen, was 3.64. This study showed a significant negative correlation between P and Lj (p < 0.05). Conclusions: As Lj gets longer, the apical foramen becomes more ovally shaped. Likewise, as it gets shorter, the apical foramen becomes more flat shaped.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.111-131
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• 1997

Eighty two of extracted bovine mandibular incisors were sectioned transversely through the cementoenamel junction(CEJ) and instrumented to a size minimum-# 110 file at the working length by 5.25 % NaOCl irrigation. The roots in group 1 were received a final irrigation with 10ml of 17% EDTA followed by 10ml of 5.25% NaOCl, group 2, 10ml of 40% citric acid followed by 10ml of 5.25% NaOCl, group 3, 20ml of 5.25% NaOCl, and control group, 20ml distilled water. Canal walls of four roots in each group and control group were examined by SEM(x3000). Calcium hydroxide was placed into all experimental roots except control group. Each root was placed in nalgen bottle containing unbuffered distilled water. The pH level of the medium surrounding tooth was recorded at 0, one hour, and daily for 1week, then 14days, 21days, and 28days using pH electrode. At 1, 3, 7, 14, 21days, and 28days, four roots from each group were split longitudinally and the ratio change was recorded using spectroiluorometer. The results were followings : 1. The smear layer was totally removed from canal walls in group 1 and 2, but was observed in group 3 and control group. 2. The hydroxyl ion diffused more rapidly through radicular dentin when smear layer was removed from canal walls. 3. The hydroxyl ion derived from calcium hydroxide began to diffuse from the root canal to the exterior surface of the root at 1day, and continued to 1-2weeks. 4. The pH level of dentin near the CEJ was not different in all experimental group regardless of presence of smear layer. It is clinically advisable to place calcium hydroxide into root canal for 1-2weeks for the purpose of expectation of diffusion of hydroxyl ion. But, after the placement of calcium hydroxide into root canal, the consequent pH level of external root surface will be futher studied with respect to it's effect on the root and periodontium.

• Imaging Science in Dentistry
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• 제31권3호
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• pp.181-184
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• 2001

Thirteen-year-old girl complaining of the swelling and pain on the left midface visited our dental hospital. On the radiographic examination, well-defined radiolucent lesion with hyperostotic border was found in the left maxilla accompanying with the external root resorption of the involved teeth and the displaced second molar. CT showed calcified bodies, thinning of hard palate, inferior orbital wall and lateral wall of nasal fossa, and thinning and perforation of the buccal plate of the maxilla. Enucleation and curettage of the lesion and nasoantrostomy was carried out and histopathologic examination mainly showed a solid tumor tissue composed of odontogenic epithelium and pulp tissues admixed with dentin and enamel formation. And some part of reduced follicular epithelium of tooth germ showed a change mimicking calcifying odontogenic cyst. Taken together, we concluded the lesion is an ameloblastic fibro-odontoma with a change of calcifying odontogenic cyst.

• Imaging Science in Dentistry
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• 제30권3호
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• pp.199-205
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• 2000

Purpose: To determine whether the significant relationship exists between radiographic appearance, whether it is unilocular or multilocular, and its corresponding clinical and histologic features by examining the odontogenic keratocyst clinically, radiologically and histologically. Materials and Methods: This study was conducted on 48 cases of odontogenic keratocyst from the files of Dental Hospital, Yonsei University for the years 1982 through 1995. Results and Conclusions : The mean age of patients was 30.5 years in the unilocular group and 35.5 years in the multilocular group. The male to female ratio was 1 : 1.06 in the unilocular group and 1 : 1.75 in the multilocular group. The chief complaint was swelling in both groups(unilocular 35.1 %, multilocular 54.5%). In the occurrence site, the border of the lesion, the displacement and external root resorption of the adjacent teeth, there were no statistically significant difference between the unilocular group and multilocular group, but in the border type, there was statistically significant difference (x²-test, p<0.05)wo recurred cases were observed among 11 cases of odontogenic keratocyst. One was unilocular case and the other was multilocular case.

• Imaging Science in Dentistry
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• 제51권4호
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• pp.455-460
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• 2021

This report presents a rare case of maxillary osteoblastoma in a 17-year-old female. The patient presented with dull pain and facial asymmetry inferior to the left zygoma. An intraoral examination found a painless swelling on the buccal gingival tissue in the left posterior maxilla. Panoramic radiographs and multidetector computed tomographic images revealed an ill-defined, non-corticated, mixed attenuating entity of osseous density located within the left posterior maxilla apical to the left maxillary molars. The entity exhibited a heterogeneous internal structure with a fine granular appearance, and the periphery showed a partial hypo-attenuating rim along the antero-medial aspect. Expansion of the left posterior maxilla accompanied with displacement of the left maxillary sinus floor was noted. External root resorption of the first and second molars was noted, as well as postero-superior displacement of the third molar. The histopathologic diagnosis of the biopsy was osteoblastoma. Complete excision of the tumor was performed.

• 대한치과교정학회지
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• 제20권3호
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• pp.447-462
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• 1990

The objective of this experiment is to observe structural differences in the othodontic movement of vital (control group) and devitalized (experimental group) teeth in the mongrel dogs. The 5 utilized dogs in this experiment were approximately 1 year of age and their average weight was about 12 Kg. Endodontic therapy was performed on the 2nd premolars in upper & lower jaws of each animal under the general anesthesia by intravascular injection of 25mg/kg of pentobarbital sodium. The canals of the teeth were obturated by using gutta percha in conjunction with root canal sealer (AH26 Densply). One of the roots in the 2nd premolars was hemisected to make an extraction space for the devitalized teeth to be moved. The edgewise technique was employed for the movement of the teeth. Orthodontic models and intraoral roentgenograms were taken before and after orthodontic tooth movement. The open coil springs (.010 x .040) were used at interbraket space in order to provide equal forces (75gm) between the teeth in each arch wire. After 13 weeks of active orthodontic tooth movement, dogs were sacrified and the experimental results w ere examined through the intraoral radiography, microscopic examination and scanning electromicroscopic examination at the root sulfate. From the results of the study, the following conclusions may be drawn: The root resolution and cemental deposition were observed within the pressure and tension site in both group. 2. The root resorbed lacunae were observed in the cementum and/or into the dentin in both group. 3. The prominent osteoblastic activities were observed on the alveolar margin in the tension site in both group. 4. A few of blood vessels were observed in the pressure site, but also lots of blood vessels were observed in the tension site especially in the periphery of the alveolar bone in both group. 5. In the pressure site, resorbed lacunae were formed with deep and narrow cavity in the control group; the shallow and wide cavity in the experimental group. 6. In the pressure site, the repaired cementum or cementoid tissue was lined on cementum in the experimental group, but not in the control group. 7. There was no significant difference between external root resolution of endodontically and vital teeth when both were subjected to orthodontic forces.