• Restorative Dentistry and Endodontics
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• 제8권1호
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• pp.139-145
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• 1982

Eighty four human maxillary second premolars were injected with china. ink, decalcified, cleared and used in study, in vitro, to determine the number of root canals, the frequency and location of lateral canals, the frequency and location of transverse ansatomoses, the curvature of root canals, the location of apical foramens, and the frequency of apical deltas. The results were as follows: 1. Most of the teeth demonstrated one canals, but the only tooth was found to have two canal. 2. Of the 101 canals studied, 85.1% of the canals were found to have lateral canals and these ramifications were usually located in the apical third of the root. 3. Of the two root canals in one root, 25.4% of the canals were found to have transverse anastomoses and were usually located in the middle third of the root 4. 33.3% of apical foramens were located directly on the root apex and 66.7% of them laterally, and 46.5% of canals showed distal curvature.

• Restorative Dentistry and Endodontics
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• 제7권1호
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• pp.139-144
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• 1981

Eighty four human maxillary first premolars were injected with china ink, decalcified, cleared and used in study, in vitro, to determine the number of root canals, the frequency and location of lateral canals, the frequency and location of transverse anastomoses, the curvature of root canals, the location of apical foramens, and the frequency of apical deltas. The results were as follows: 1. Most of the teeth demonstrated two canals, but 20.2% of the teeth were found to have one canal. 2. Of the 151 canals studied, 38.4% of the canals were found to have lateral canals and these ramifications were usually located in the apical third of the root. 3. Of the two root canals in one root, 35.7% of the canals were found to have transverse anastomoses and were usually located in the middle third of the root. 4. 15.2% of apical foramens were located directly on the root apex and 84.8% of them laterally, and 52.3% of canals showed distal curvature.

• 대한소아치과학회지
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• 제30권4호
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• pp.637-642
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• 2003

유치근의 치근이개와 만곡에 관련된 형태학적 특성은 치열교환기의 치근 흡수 및 근단 병소의 양상을 결정지을 뿐 아니라, 성공적인 치수치료에 심대한 영향을 미친다. 본 연구는 하악 제 2유구치 근관 만곡의 각도, 반경 및 만곡 시작점을 측정해 봄으로써, 유치근과 근관의 해부학적 형태를 정밀 분석할 목적으로 시행되었다. 연구재료로는 $3{\sim}6$세의 어린이의 제 2 유구치 구내 치근단 방사선 사진 50매를 사용하였다. 근단공이 미완성이거나 흡수된 것을 제외하고, 방사선상의 왜곡이 적으며 근관 형태의 판독이 가능한 것을 선택하고, 자료를 digital image화하여 이미지 분석용 software Scion Image Beta 4.02 (Scion Co. USA)를 이용하여 만곡을 분석하였다. 그리고 Schneider법에 의해 만곡도를 측정하고, Schaefer 등의 방법에 의해 만곡반경을 측정하였으며, 아울러 만곡개시거리를 측정하고 근원심근 간의 비교를 통하여 다음과 같은 결과를 얻었다. 1. 제 2유구치의 만곡도는 근심근에서 $17.3^{\circ}{\pm}5.0$, 원심근에서 $27.9^{\circ}{\pm}6.0$로 원심근에서 크게 나타났다(p<0.05). 2. 만곡반경은 근심근에서 $8.7\;mm{\pm}2.5$, 원심근에서 $5.8\;mm{\pm}1.5$로 근심근에서 크게 나타났다(p<0.05). 3. 만곡개시거리는 근심근에서 $4.1\;mm{\pm}0.6$, 원심근에서 $4.2\;mm{\pm}0.6$로 양 근간에 차이가 없었다(p<0.05).

• Restorative Dentistry and Endodontics
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• 제26권5호
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• pp.418-435
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• 2001

Root canal preparation process is of utmost importance in successful treatment of root canal. Also, one of the most important purpose of the root canal preparation is to enlarge the root canal three dimensionally without changing the curvature of the root canal However as the curvature of the root canal increases, there are many difficulties involved in formation of optimum root canal. Therefore in order to solve the above mentioned problems, new developments in methods of root canal preparation and equipments for such purposes were made. Recently, vigorous studies about newly introduced engine-driven nickel-ti-tanium rotary file are conducted. As shown in research results to dates, it is well established that the use of nickel-titanium file is better suited for curved root canal than stainless steel file in maintaining the curvature or root canal and reducing the deformation of root canal. However it is also acknowledged that there are a few discrepancies in research results according to protocol, due to failure to remove variables in experiments. In addition, although it is recommended by the manufacturer that the GT rotary file should maintain a low rotational speed of 150~350rpm and 'light pressure' as light as not to break the lead of a pencil, academic studies about the vertical force which is not yet standardized are not sufficiently explored. Therefore, this research devised and utilized a special research equipment to standardize the appropriate range of vertical force for GT rotary file through experiments by breaking of the lead of a pencil as expressed by the manufacturer and to accurately measure factors involved through repeating and recreating the environment of root canal preparation. Forming nine experimental groups by varying the vertical forces (150g. 220g, 300g) and rpm (150rpm, 250rpm, 350rpm), the effects of changing vertical forces and rpm on working efficiency were measured in terms of time expended in root canal preparation by crown-down method using a transparent resin block with 35 degree curvature and GT rotary file (z-test). The following research using this special research equipment that involved nine experimental groups and varying the vertical force for root canal preparation from 300g which is within the normal vertical force range to 700g and 1000g which fall outside the normal rpm range. The results were as follows : 1. Analysis of the experiment results revealed that the time spent in root canal preparation decreased as the vertical forces and rpm increased (p<0.05). Also, the effects of rpm were greater than those of the vertical forces within the normal vertical force range ($\beta$-weight test). 2. Observation of the deformation of GT rotary file revealed that deformation increases in a direct correlation with the vertical force increase and in a reverse correlation with the rpm decrease. In the case of the vertical forces close to the normal range, the probability of GT rotary file deformation were quite different depending on the rpm changes. In the case of greater vertical forces, the occurrences of deformation of the file were more frequent regardless of the rpm changes. 3. Deformation and breakage of file were also commonly observed in the expended time measurement experiments and GT rotary file deformation experiments in which low speed rpm (150rpm) was used and at the curved portion of the resin block.

• Imaging Science in Dentistry
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• 제36권1호
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• pp.55-62
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• 2006

Purpose : To find the cause of root curvature by use of panoramic and lateral cephalometric radiograph. Materials and Methods : Twenty six 1st graders whose mandibular 1st molars .just emerged into the mouth were selected. Panoramic and lateral cephalometric radiograph were taken at grade 1 and 6, longitudinally. In cephalometric radio graph, mandibular plane angle, ramus-occlusal plane angle, gonial angle, and gonion-gnathion distance (Go-Gn distance) were measured. In panoramic radio graph, elongated root length and root angle were measured by means of digital subtraction radiography. Occlusal plane-tooth axis angle was measured, too. Pearson correlations were used to evaluate the relationships between root curvature and elongated length and longitudinal variations of all variables. Multiple regression equation using related variables was computed. Results : The Pearson correlation coefficient between curved angle and longitudinal variations of occlusal plane-tooth axis angle and ramus-occlusal plane angle was 0.350 and 0.401, respectively (p<0.05). There was no significant correlation between elongated root length and longitudinal variations of all variables. The resulting regression equation was $Y=10.209+0.208X_1+0.745X_2$ (Y: root angle, $X_1$: variation of occlusal plane-tooth axis angle, $X_2$: variation of ramus-occlusal plane angle). Conclusion : It was suspected that the reasons of root curvature were change of tooth axis caused by contact with 2nd deciduous tooth and amount of mesial and superior movement related to change of occlusal plane.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
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• pp.554-554
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• 2003

I. Objectives This study was done to evaluate the shaping ability of ProFile and ProTaper, K-Flexofile during instrumentation in simulated resin canals with different angles of curvature. II. Materials and Methods Ninety simulated root canals with a curvature of 15, 30 and 45 degree (following Schneider's method) were made of epoxy resin ($EPOXICURE^{TM}$, BUEHLER, USA) for this study. The canal length of simulated root canals was adjusted to 18 mm. The beginning point of curvature was positioned at 10mm from the canal orifice.(omitted)

• Restorative Dentistry and Endodontics
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• 제35권5호
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• pp.374-379
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• 2010

연구목적: 근관의 만곡도가 니켈-티타늄 전동파일의 screw-in effect에 미치는 영향을 평가하고자 하였다. 연구 재료 및 방법: 0, 10, 20, 그리고 30도의 만곡을 가지는 80개의 레진모형근관 (Nissin Dental Prod. Inc.)에서 0.06 경사도 30번 전동화일 (ProTaper, Dentsply-Maillefer)을 분당 300회전, 단일 pecking 동작으로 기구조작하였으며 dynamometer를 이용하여 발생한 screw-in force를 측정하였다. 결과치는 one-way ANOVA로 통계처리 하였고, Scheffe multiple range test를 사용하여 95% 수준에서 유의성을 검정하였다. 결과: 근관의 만곡도가 작을수록 screw-in force가 높게 나타났으며 (p < 0.001), 모든 그룹 간에 유의성 있는 차이를 보였다. 결론: 이 결과로 미루어 볼 때, 근관의 만곡도가 작을수록 screw-in force가 많이 발생하는 것으로 보여지며, 따라서 기구조작 동안의 screw-in force를 방지 또는 억제하기 위해서는 만곡도가 작은 근관을 성형할 때 더 많은 주의가 요구될 것으로 생각된다.

• 생명과학회지
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• 제17권2호통권82호
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• pp.174-178
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• 2007

malformin A1은 옥수수 뿌리에서 대조구와 비교하여 에틸렌 생성을 4시간에는 130%, 8시간에는 56%를 각각 촉진하였다. 에틸렌 생성량이 4시간을 최대로 하여 8시간까지 서서히 증가율이 감소하였다. 칼슘 이온 조절제인 A23187 (calcium ionophore)과 verapamil (calcium channel blocker)을 각각 단독으로 처리한 경우 모두 대조구와 비교하여 4시간에는 30%, 8시간에는 20% 정도로 에틸렌 생성을 촉진하였다. 칼슘 이온 조절제가 malformin A1에 의해 유도된 에틸렌 생성에 미치는 영향을 조사한 결과 4시간에는 malformin A1만 처리하였을 경우에 관찰되는 수준만큼 촉진되지 않았지만 칼슘 이온 조절제의 촉진 효과는 8시간까지 유지되었다. 이러한 결과는 malformin A1이 에틸렌 생성을 촉진하기 위하여 적절한 칼슘 농도가 필요할 가능성을 제시하고 있다. Malformin A1은 굴중성 굴곡 반응을 대조구와 비교하여 4시간과 8시간에 각각 58%와 42% 정도 억제하였다. A23187과 달리, verapamil은 굴중성 굴곡반응을 4시간과 8시간에 대조구와 비교하여 각각 54%와 23%를 억제하였다. 더 나아가 verapamil은 malformin A1에 의해 유도된 굴중성 굴곡 반응을 A23187보다 더 억제하였다. 이러한 결과는 칼슘이온 조절제가 malformin A1에 의해 유도된 옥수수 뿌리의 굴중성 반응에 영향을 주며, 칼슘 이온이 굴중성 반응에 중요한 역할을 한다는 증거를 제시한다.

• Restorative Dentistry and Endodontics
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• 제30권4호
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• pp.327-334
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• 2005

본 연구에서는 ProFile로 근관형성 시 anticurvature filing 방법의 영향을 평가하고자 하였다 변형된 Bramante 법을 이용해 36개의 레진 블록을 치근단으로부터 8mm부위와 근관의 최대 만곡 부위에서 절단한 후 재조립하였다. 근관형성의 동작에 따라 anticurvature filing motion, circumferential filing motion, straight up-and-down motion의 3가지 실험군으로 분류한 다음 ProFile로 근관을 형성하였으며, 술 전$\cdot$후의 단면을 stereomicroscope로 촬영, 저장하고 중첩하여 근관 단면의 변화와 근관의 중심 이동률을 비교 평가하였다. 모든 위치에서 단면적 변화량, 만곡 내측으로의 형성량과 중심 이동률은 세 군간에 유의한 차이가 없었으며, 만곡 외측으로의 형성량은 치근단으로부터 8mm 부위에서 anticurvature filing motion, circumferential filing motion, straight up-and-down motion의 순으로 많았으나, 근관의 최대 만곡 부위에서는 차이가 없었다 이상의 결과에서 만곡 근관의 위험 부위에서 ProFile로 근관형성 시 anticurvature filing motion의 영향은 다른 motion과 비교해 볼 때 유의할 만한 차이가 없는 것으로 생각된다.

• Restorative Dentistry and Endodontics
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• 제46권1호
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• pp.5.1-5.13
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• 2021

Objectives: The aim of the current study was to assess whether the amount of extruded debris differs for straight and severely curved root canals during retreatment using H-files, R-Endo, Reciproc and ProTaper Universal Retreatment (PTU-R) files. Additionally, the area of residual filling material was evaluated. Materials and Methods: Severely curved (n = 104) and straight (n = 104) root canals of maxillary molar teeth were prepared with WaveOne Primary file and obturated with gutta-percha and AH Plus sealer. Root canal filling materials were removed with one of the preparation techniques: group 1: H-file; group 2: R-Endo; group 3: Reciproc; group 4: PTU-R (n = 26). The amount of extruded material and the area of the residual filling material was measured. The data were analyzed with 2-way analysis of variance (ANOVA) and 1-way ANOVA at the 0.05 significance level. Results: Except for Reciproc group (p > 0.05), PTU-R, R-Endo, and H-file systems extruded significantly more debris in severely curved canals (p < 0.05). Each file system caused more residual filling material in severely curved canals than in straight ones (p < 0.05). Conclusions: All instruments used in this study caused apical debris extrusion. Root canal curvature had an effect on extruded debris, except for Reciproc system. Clinicians should be aware that the difficult morphology of the severely curved root canals is a factor increasing the amount of extruded debris during the retreatment procedure.