• Restorative Dentistry and Endodontics
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• 제43권2호
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• pp.16.1-16.9
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• 2018

Objectives: Understanding the reason for an unsuccessful non-surgical endodontic treatment outcome, as well as the complex anatomy of the root canal system, is very important. This study examined the cross-sectional root canal structure of mandibular first molars confirmed to have failed non-surgical root canal treatment using digital images obtained during intentional replantation surgery, as well as the causative factors of the failed conventional endodontic treatments. Materials and Methods: This study evaluated 115 mandibular first molars. Digital photographic images of the resected surface were taken at the apical 3 mm level and examined. The discolored dentin area around the root canal was investigated by measuring the total surface area, the treated areas as determined by the endodontic filling material, and the discolored dentin area. Results: Forty 2-rooted teeth showed discolored root dentin in both the mesial and distal roots. Compared to the original filled area, significant expansion of root dentin discoloration was observed. Moreover, the mesial roots were significantly more discolored than the distal roots. Of the 115 molars, 92 had 2 roots. Among the mesial roots of the 2-rooted teeth, 95.7% of the roots had 2 canals and 79.4% had partial/complete isthmuses and/or accessory canals. Conclusions: Dentin discoloration that was not visible on periapical radiographs and cone-beam computed tomography was frequently found in mandibular first molars that failed endodontic treatment. The complex anatomy of the mesial roots of the mandibular first molars is another reason for the failure of conventional endodontic treatment.

• Restorative Dentistry and Endodontics
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• 제41권4호
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• pp.322-331
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• 2016

Variation in the root and canal morphology of the maxillary first molars is quite common. The most common configuration is 3 roots and 3 or 4 canals. Nonetheless, other possibilities still exist. The presence of an additional palatal root is rather uncommon and has been reported to have an incidence of 0.06 - 1.6% in varying populations studied. Whenever two palatal roots exist, one of them is the normal palatal root, the other is a supernumerary structure which can be located either mesiolingually (radix mesiolingualis) or distolingually (radix distolingualis). This case report describes successful endodontic treatment of a maxillary first molar with radix mesiolingualis and radix distolingualis. Identification of this variation was done through clinical examination along with the aid of multiangled radiographs, and an accurate assessment of this morphology was made with the help of a cone-beam computed tomography imaging. In addition to the literature review, this article also discusses the epidemiology, classifications, morphometric features, guidelines for diagnosis, and endodontic management of a maxillary first molar with extra-palatal root.

• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.517-529
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• 1996

The purpose of this study was to evaluate the apical sealing ability of the Thermafil endodontic obturation technique and to compare it with lateral condensation technique. 42 straight canals from extracted human anterior teeth and 42 curved canals(> $25^{\circ}$) from maxillary and mandibular molar teeth were selected. And 80 of them were divided into four groups, 20 canals respectively. The teeth in prior two groups had straight canals and the other two groups had curved canals. The rest of four canals served as positive and negative controls. After resecting anatomical crowns, all canals were prepared using a standard step-back technique. Lateral condensation was used to obturate two groups, one group of straight ones the other curved. And Thermafil obturators were also used in the same two groups. Obturated teeth were infiltrated by India ink for a week, decalcified and cleared with 5% nitric acid and methyl salicylate. The apical leakage and the frequency of filled lateral and accessory canals were measured with stereomicroscope and also apical extrusion of sealer and gutta-percha and obturation time were checked and the data were analyzed statistically(one-way ANOVA, t-test, Chi-square test). The results were as follows : 1. There was no significant difference in the degree of dye penetration between Thermafil and lateral condensation groups(p>0.05). 2. Apical extrusion of sealer and gutta-percha occurred significantly more often with Thermafil obturators in straight canals(p<0.05), but not significantly different in curved canals(p>0.05). 3. Canal obturation time with Thermafil obturators was significantly faster than lateral condensation (p<0.05). 4. The Thermafil groups showed a higher frequency of filled lateral and accessory canals than in the lateral condensation groups. But the difference was not statistically significant (p>0.05).

• Restorative Dentistry and Endodontics
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• 제30권2호
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• pp.79-85
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• 2005

최근, 다양한 경사도의 니켈-티타늄 근관기구와 더불어 다양한 경사도의 gutta-percha cone이 소개되었다. 효율적인 근관 충전을 위해서는 짧은 시간에 적은 수의 기구 및 재료를 사용하여 균일한 gutta-percha로 근관을 충전할 필요가 있다. 본 연구에서는 0.06 경사도의 니켈-티타늄 전동화일로 형성된 만곡 근관에서 측방 가압법으로 근관충전시 비표준화 medium 크기 master gutta-percha cone의 충전효율을 ISO 표준화 규격의 master cone과 비교하여 평가하고자 하였다. 60개의 모형레진 만곡근관에서 0.06 경사도의 니켈-티타늄 전동화일 ($ProTaper^{TM},\;ProFile^{(R)}$, Dentsply-Maillefer, Ballaigues, Switzerland)을 사용하여 근단부 근관이 30번 크기가 되게 crown-down법으로 근관을 형성하였다. 근관은 master gutta-percha cone, AH 26 실러 (Dentsply-DeTrey, Konstanz, Germany), 그리고 type A accessory cone (Dentsply-Maillefer, Ballaigues, Switzerland)을 사용하여 측방가압법으로 충전하였으며, 이 때 사용된 master gutta-percha cone(Diadent, Chongju, Korea)과 Finger spreader(B type, Dentsply-Maillefer, Ballaigues, Switzerland)에 따라 임의로 15개씩 4개의 군으로 나누어 실험하였는데, St/SS 군에서는 ISO 표준화 규격의 30번 master cone과 스테인레스 스틸 finger spreader를, St/NT 군에서는 ISO 표준화 규격의 30번 master cone과 니켈-티타늄 finger spreader를, Non-St/SS 군에서는 비표준화 medium 규격 master cone과 스테인레스 스틸 spreader를, 그리고 Non-St/NT 군에서는 비표준화 medium 크기 master cone과 니켈-티타늄 finger spreader를 각각 사용하였다. 충전된 근관은 $37^{\circ}C$, 상대습도 $100\%$하에서 24시간 보관한 후, 치근단 1, 3및 5 mm수준에서 횡절단하여 입체현미경 하에서 관찰하고 컴퓨터에 저장한 다음, $Auto^{(R)}$CAD 2000 프로그램을 이용하여, 형성된 근관 및 gutta-percha 충전물의 외형을 추적하여 근관내 gutta-percha 면적비를 계산하였다. Gutta-percha 면적비의 결과치는 two-way ANOVA를, 그리고 accessory cone 수는 one-way ANOVA 및 Duncan's multiple range test를 이용하여 통계 분석하여 다음과 같은 결과를 얻었다. 스테인레스 스틸 finger spreader를 사용한 경우 및 니켈-티타늄 finger spreader를 사용한 경우 공히, 모든 치근단 수준에서 비표준화 medium 크기 master cone 사용군이 ISO 표준화 규격의 master cone 사용군에 비해 유의하게 높은 gutta-percha 면적비를 나타내었다 (p < 0.01). 비표준화 medium크기 master cone 사용군에서는 표준화 규격의 master cone 사용군에 비해 유의하게 적은 수의 accessory cone이 사용되었다 (p < 0.01).

• 한국산림과학회지
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• 제24권1호
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• pp.53-61
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• 1974

전남(全南) 신안군(新安郡) 흑산면(黑山面) 홍도리(紅島里)에 위치(位置)하고 있는 홍도(紅島)의 적송집단(赤松集團)을 대상(對象)으르 개체(個體)의 수형(樹型), 분지각(分枝角), 수피색(樹皮色), 추재율(秋材率) 침엽장(針葉長), 수지도(樹脂道)의 위치(位置)와 수(數) 등이 조사(調査)되었다. 홍도(紅島)에 자라는 송류(松類)는 적송(赤松)이 대부분(大部分)으로 필자(筆者)는 조사(調査)도중 단일주(單一株)의 해송치수(海松稚樹)를 발견(發見)하였을 뿐이다. 20년생(年生) 이상의 적송(赤松) 14개체(個體)의 침엽(針葉)을 검경(檢鏡)한바 어느 정도(程度)의 해송인자(海松因子)가 혼입(混入)되어 있었다. 밀엽형개체(密葉型個體)와 소엽형개체(疎葉型個體)를 볼 때 부수지도(副樹脂道)의 수(數)가 현저하게 적은 것이 특징(特徵)이며 특히 소엽형(疎葉型)의 경우 부수지도(副樹脂道)의 수(數)가 1.3 이라는 평균치(平均値)를 보였다. 현 단계로서는 과거부터 홍도(紅島)에 해송(海松)이 있었던 것으로 보기 어렵고 해안일대(海岸一帶)에 분포(分布)하는 해송(海松)으로부터 화분(花粉) 비산공여(飛散供與)되는 것으로 생각된다.

• Journal of Periodontal and Implant Science
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• 제35권1호
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• pp.177-185
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• 2005

The purpose of the study was to investigate the influence of an endodontic infection on presence of furcation involvement in periodontally-involved mandibular molars. All first and second mandibualr molars in 45 patients were selected if at least one was root-filled or had a possible periapical radiolucency. The sample consisted of patients from a referral population at a periodotnal clinic which represented an adult population with a mean age of 47.5 years (range 31 to 63) For mandibular molars with periapical destruction at both roots, frequency of horizontal furcation depth ${\geqq}$ 3 mm was significantly more compared to teeth without periapical destruction. Mean periodontal probing depth was significantly greater at mandibular molars with periapical destruction. It is suggested that a root canal infection in periodontitis-involved molars may potentiate periodontitis progression by spreading of endodontic pathgens through patent accessory canals and dentinal tubules. In conclusion, an endodontic infection in mandibular molars was found to be associated with additional attachment loss in the furcation area, and may thus be considered to be one of several risk factors influencing the prognosis of molars in periodontitis-prone patients.

• Restorative Dentistry and Endodontics
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• 제34권2호
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• pp.137-144
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• 2009

본 연구는 한국인의 하악 제1 대구치 60개를 대상으로 생리적 근단공의 크기와 형태, 근심 치근의 치근단 3mm에서 isthmus의 발생 빈도와 형태, 그리고 원심 치근의 치근단 3mm의 근관 형태를 입체현미경하에서 60배로 조사한 결과 다음과 같은 결론을 얻었다. 1.근심 치근은 두 개의 근단공을 가지는 비율이 높았으며(51.67%), 원심 치근은 하나의 근단공을 가지는 비율이 높았다(71.66%). 2. 부근단공의 빈도는 근심 치근의 1개의 근단공을 가지는 경우가 가장 높았다(26.07%) 3. 생리적 근단공의 크기는 근심 치근에서 하나의 근단공을 가지는 경우 0.329mm, 근심 협측 근단공은 0.266mm, 근심 설측 근단공은 0.246mm였으며, 원심 치근에서 하나의 근단공을 가지는 경우 0.375mm, 원심 협측 근단공은 0.291mm, 원심 설측 근단공은 0.237mm로 나타났다. 4. 근단공의 형태는 oval 형태 (69.93%)가 가장 많았다. 5.근심 치근의 치근단 3mm에서 isthmus의 발생빈도는 55%였으며, partial isthmus는 31.66%, complete isth-mus는 23.34%로 나타났다. 6.원심 치근의 치근단 3mm의 근관 형태는 oval형태(50.64%)가 가장 많았다. 이상의 연구 결과 하악 제1대구치의 성공적인 근관 치료를 위해서는 생리적 근단공의 실제 크기와 형태 및 isthmus의 존재에 대한사전 지식이 필요할 것이다.

• 한국패류학회지
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• 제5권1호
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• pp.1-9
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• 1989

A scanning electron microscopic study on the glochidium and glchidial encystment of Anodonta grandis on the guppy was conducted. The shape of the glochidium is apparently triangular and its averge size is 0.45mm X0.4mm when closed, The two glochidial shell valves are of the same size, kept together by a ligament of 120${\mu}{\textrm}{m}$ in length and 7 ${\mu}{\textrm}{m}$ in width. Each of the glochidial shell valves has a 16 ${\mu}{\textrm}{m}$ long hook sitdded with many spines on the superior face. A large area to the apex of the valve surrounding the base of the hook is provided with numerous small spines which become progressively smaller towards the periphery of the area, The external surface of the glochidial shell valve is covered with numerous small processes showing successive change in the shape and the pattern of destribution by part. Besides the processes, there are a number of niches scattered all over the exterior surface. The glochidial shell valve has two layers. One is the outer thin membrane bearing the processes and the niches and the others is the inner layer bearing numerous holes which any accessory structure and 2.65 ${\mu}{\textrm}{m}$ in diameter, emerges from a canal located at center of ventral plate of the mamtle, A total of three types of the hair cells are observed. In present artificial infection of the glochidium to the guppy, it took about three to four hours to complete an early cysts, During the period of encystment, The epithelial cells of the host fish actively migrated toward the attached glochidium and covered it.