• Restorative Dentistry and Endodontics
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• v.32 no.4
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• pp.335-342
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• 2007

C-shaped canals are known to present a complex canal anatomy with numerous fins connecting individual canals, thus requiring supplementary effort to accomplish a successful root canal treatment. This study examined the frequency of the C-shaped mandibular second molars and interrelation between the clinical records and radiographs to recognize them treated in the Department of Conservative Dentistry of the Chosun University Dental Hospital during a six-year period (1998-2004). This study reviewed the clinical records of 227 patients who underwent root canal treatment of the mandibular second molars. After opening the chamber, those cases with C-shaped orifices in the pulpal floor were selected, ana the C-shaped root canal types were classified according to Melton's criteria. Three experienced dentists evaluated the radiographs of the C-shaped mandibular second molar on a viewer using a magnifying glass in order to determine if the root apex was fused or separated, the distal root canal was either centered or mesial shifted in the distal root, and if there was bilateral symmetry in a panorama. In conclusion, there is a high frequency of C-shaped mandibular second molars in Koreans. Simultaneous interpretation of the root shape and distal root canal using the preoperative, working length and post-treatment radiographs is important for diagnosing a C-shaped mandibular second molar.

• Restorative Dentistry and Endodontics
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• v.34 no.5
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• pp.390-396
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• 2009

The aim of this study was to evaluate endodontic irrigation methods with $EndoVac^{(R)}$ and $EndoActivator^{(R)}$ in the elimination of Enterococcus faecalis from the root canals. Extracted 70 human single-rooted teeth were used. The canals were instrumented by a crown-down technique with .04 taper ProFile to ISO size 40. After the teeth were autoclaved, the canals were inoculated with E. faecalis and incubated for 48 h. The teeth were randomly divided into three experimental groups of 20 teeth each according to canal irrigation methods and two control groups as follows: group 1 - $EndoVac^{(R)}$; group 2 - $EndoActivator^{(R)}$; group 3-Conventional needle irrigation method. After canal irrigation using 2.5% NaOCl. first samples (S1) were taken using sterile paper point. And the canals were filled with sterile brain heart infusion (BHI) broth and incubated for 24 h, then second samples (S2) were taken. The samples were cultured on BHI agar plate to determine the numbers of colony forming units (CFU). In first sampling (S1), only one canal of conventional method among the all experimental groups was positive cultured. In second sampling (S2), $EndoVac^{(R)}$ group showed the least positive culture numbers of E. faecalis. There was statistically significant difference between the $EndoVac^{(R)}$ and conventional needle irrigation methods in the mean value of Log CFU. According to the results of this study, $EndoVac^{(R)}$ showed better efficacy than conventional needle irrigation method in the elimination of E. faecalis from the root canal.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.494-498
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• 2000

이 연구의 목적은 'Three-File' 방식에 의한 근관형성시 근관의 형태변화 및 전이정도를 분석하고 이를 기존의 근관형성방법과 비교하고자 하는 것이다. 만곡된 근관을 가진 투명한 레진블럭 상에서 'Three-File' 방식, crown-down방식 및 스테인레스강 화일에 의한 수동방식으로 근관형성을 시행하고 이를 똑같은 위치가 재현가능한 고정틀에 위치시킨 후 사진의 이중노출 기법을 이용하여 근관형성 전후의 근관의 형태변화 및 전이정도를 분석한 결과 다음과 같은 결과를 얻었다. 1. 스테인레스강 화일의 경우 근관확대가 가장 컸고 근관의 전이정도도 심하였으며, 형성된 근관이 taper하지 못하고 불규칙한 형태를 보였다. 2. Profile로 crown-down방식에 의해 형성한 경우 taper한 근관형태를 보였고, 근관의 전이 정도도 스테인레스강 화일의 경우보다 작았다(p<0.01). 3. Profile로 'Three-File'방식에 의해 형성한 경우 taper한 근관형태를 보였고 근관의 전이정도도 스테인레스강 화일의 경우보다 유의하게 작았으나(p<0.01), crown-down방식에 의해 형성한 경우와 유의할 만한 차이는 없었다(p>0.01).

• Restorative Dentistry and Endodontics
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• v.32 no.6
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• pp.550-558
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• 2007

The purpose of this study was to evaluate the insertion depth of several brands of master gutta percha cones after shaping by various Ni-Ti rotary files in simulated canals. Fifty resin simulated J-shape canals were instrumented with ProFile, ProTaper and HEROShaper. Simulated canals were prepared with ProFile .04 taper #25(n=10), .06 taper #25(n=10), ProTaper F2(n=10), HEROShaper .04 taper #25(n=10) and .06 taper #25(n=10). Size #25 gutta percha cones with a .04 & .06 taper from three different brands were used: DiaDent; META; Sure-endo. The gutta percha cones were selected and inserted into the prepared simulated canals. The distance from the apex of the prepared canal to the gutta percha cone tip was measured by image analysis program. Within limited data of this study, the results were as follows 1. When the simulated root canals were prepared with HEROShaper, gutta-percha cones were closely adapted to the root canal. 2. All brands of gutta percha cones fail to go to the prepared length in canal which was instrumented with ProFile, the cones extend beyond the prepared length in canal which was prepared with ProTaper. 3. In canal which was instrumented with HEROShaper .04 taper #25, Sure-endo .04 taper master gutta percha cone was well fitted(p < 0.05). 4. In canal which was instrumented with HEROShaper .06 taper #25, META .06 taper master gutta percha cone was well fitted(p < 0.05). As a result, we concluded that the insertion depth of all brands of master gutta percha cone do not match the rotary instrument, even though it was prepared by crown-down technique, as recommended by the manufacturer. Therefore, the master cone should be carefully selected to match the depth of the prepared canal for adequate obturation.

• Restorative Dentistry and Endodontics
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• v.31 no.2
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• pp.125-132
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• 2006

This study was conducted to evaluate the insertion depth of Buchanan plugger after shaping by various Ni-Ti rotary files. It was conducted to determine which size of plugger are appropriate, when root canals are shaped with Ni-Ti rotary files and obturated by Continuous wave of condensation technique. Two type of eighty simulated resin blocks were used : J-shaped and straight shaped canal. The simulated canals were instrumented by ProTaper and ProFile. Buchanan pluggers were inserted into the canal, and then the image was recorded to scanner. The distance from the apex of the canal to the plugger tip was measured by image analysis program. Data were analyzed by one-way ANOVA followed by Scheffe's test. The results were as follows 1. In straight canal finished up to ProTaper F2 and F3 file, F and FM pluggers were inserted more than 5 mm short of working length. 2. In J-shaped canal finished up to ProTaper F2 file, F pluggers were inserted more than 5 mm short of working length. Finished up to ProTaper F3 file. F and FM pluggers were inserted more than 5 mm short of working length. 3. In straight and J-shaped canal finished up to ProFile .06/#20 and .06/#25, any of Buchanan plugger could not be inserted more than 5 mm short of working length. These results suggest that canals shaped by ProTaper could be obturated by Continuous wave of condensation technique with F and FM size Buchanan plugger.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.32-37
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• 2016

Purpose: To determine the anatomical characteristic of C-shaped canal systems in Korean mandibular 2nd molars by cone beam computed tomography (CBCT). Materials and Methods: The 824 CBCT images were evaluated. These patients were taken CBCT for the diagnosis and treatment of dental implantation on 2013. The 711 mandibular 2nd molars were examined. The configuration of root canal systems were classified according to modified Melton's classifications. Results: Of the 711 mandibular 2nd molars, 21.5% had C-shaped canal systems. This prevalence did not differ with tooth position. Most of the C-shaped canals with bilateral molars were symmetrical. Of the C-shaped canal, the most common configuration Type were Melton's Type I (89%) in the orifice level and Melton's III (83.8%) in the apical level. The prevalence of C-shaped canal was higher in female (25%) than male (13.9%) (P < 0.05). Conclusion: A high prevalence of C-shaped canals were observed in Korean mandibular 2nd molars. For successful C-shaped root canal treatment, the comprehension of root canal systems was important.

• Restorative Dentistry and Endodontics
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• v.26 no.3
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• pp.206-214
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• 2001

근관계의 완전한 충전을 위해 기계적인 근관 확대 및 화학적인 세척은 필수 불가결하다. 근관내 기구 조작 시 근관벽에는 무기물과 유기물로 구성된 도말층이 형성되는데, 이 층은 서서히 분해되어 충전재 주위에서 미세누출을 야기하고, 세균과 그 부산물이 이동할 수 있는 통로를 제공하기 때문에 제거되어야 한다. 현재 이러한 목적을 위해 다양한 기구들과 세척 용액들이 이용되고 있다. 최근에는 근관확대를 위해 엔진 구동형 니켈-티타늄 파일이 개발되어 임상에서 널리 사용되고 있으며, 이러한 엔진 구동형 파일을 사용할 때는 윤활제의 사용이 필수적이다. 현재 시판되고 있는 윤활제들에는 도말층 제거를 위한 EDTA가 함유되어 있다. 따라서, 본 연구의 목적은 엔진 구동형 니켈-티타늄 파일을 이용해 근관을 확대할 경우 이런 윤활제들의 도말층 제거 효과를 비교 평가하는 것이다. 본 실험에는 75개의 치아가 각각 15개씩 5개의 군으로 분류되어 사용되었다. 대조군은 윤활제를 사용하지 않은 경우이고, 실험 1군에서는 윤활제로 RC-PREP$^{TM}$이, 실험 2군에서는 Glyde$^{TM}$가 각각 사용되었고. 실험 3군은 RC-PREP$^{TM}$을 사용한 후 17% EDTA로 처리하였으며. 실험 4군은 Glyde$^{TM}$를 사용한 후 17% EDTA로 처리하였다. 처리된 시편을 절단한 후 주사전자현미경을 통해 시편의 근관의 중앙부와 치근단 부위를 관찰하여 얻어진 결과는 다음과 같다. 1. 대조군과 실험군의 비교시, 대조군에서 더 많은 양의 도말층이 관찰되었고, 이는 통계학적으로 유의성이 있었다 (p<0.01). 2. 윤활제의 종류에 따른 비교 시, Glyde$^{TM}$를 사용한 2군에서 RC-PREPTM을 사용한 1군 보다 더 적은 양의 도말층이 관찰되었지만, 이는 통계학적으로 유의성이 없었다. 3. 윤활제 사용과 EDTA 처리에 따른 효과 비교 시, EDTA로 처리한 3, 4군에서 윤활제만을 사용한 1, 2군 보다 더 적은 양의 도말층이 관찰되었으며, 이는 통계학적으로 유의성 이 있었다(P<0.01). 4. 치근 중앙부와 치근단 부위에서의 도말층 제거 효과 비교 시, 1, 2군에서는 치근 중앙부에서 더 적은 양의 도말층이 관찰되었고, 통계학적으로 유의성이 있었다(P<0.01). 3, 4군에서는 중앙부의 도말층이 더 적었지만 통계학적으로 유의성이 없었다. 이상으로부터 EDTA가 함유된 윤활제를 함께 사용하면서 엔진구동형 니켈-티타늄 파일로 근관확대 시, 근관벽에 형성된 도말층 제거에 대한 파일의 효능이 상승되었다. 그러나, 윤활제의 도말층 제거 효과는 17% EDTA용액으로 근관벽을 처리하는 것보다는 낮았다 따라서, 엔진구동형 니켈-티타늄 파일로 근관확대 시 EDTA가 함유된 윤활제를 함께 사용하는 것이 요구되고, 보다 완벽하게 도말층을 제거하기 위해서는 충전 전에 17% EDTA 용액으로 근관벽을 처리하는 것이 필요하다고 사료된다.

• Restorative Dentistry and Endodontics
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• v.35 no.6
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• pp.429-435
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• 2010

Objectives: The aim of this study was to investigate average working lengths of Korean posterior teeth and evaluate validity of endodontic file length. Materials and Methods: The endodontic working length of the posterior teeth of 670 Korean patients were measured than each mean value and standard deviation were investigated than the frequency deviation and standard deviation per each length were calculated. Results: Among the canals of premolar, 66.5% of canal length was marked under 20 mm by endodontic working length and 95.4% could be measured under 22 mm and Among the canals of molars, 95.5% of canal length was marked under 20 mm endodontic working length. Conclusions: With the result of measurement of endodontic working length of premolars of Korean, it suggested that 23 mm endodontic file is more proper than the 21 mm and 25 mm file on the market.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.508-514
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• 2009

The purposes of this study were to compare the efficacy of irrigation systems by removing a calcium hydroxide $(Ca(OH)_2)$ paste from the apical third of the root canal and the effect of the patency file. Sixty single rooted human teeth were used in this study. The canals were instrumented by a crown-down manner with .04 taper ProFile to ISO #35. $Ca(OH)_2$ and distilled water were mixed and placed inside the root canals. The teeth were divided into 6 groups according to the root canal irrigation system and the use of patency file as follows: group 1 - conventional method: group 2 - $EndoActivator^{(R)}$: group 3 - $EndoVac^{(R)}$; group 4 - conventional method, patency: group 4 - $EndoActivator^{(R)}$, patency; group 6 - $EndoVac^{(R)}$, patency. All teeth were irrigated with sodium hypochlorite. After the root canal irrigation, the teeth were split in bucco-lingual aspect. Percentage of the root canal surface coverage with residual $Ca(OH)_2$ until 3 mm from working length was analyzed using Image Pro Plus ver. 4.0. Statistical analysis was performed using the One-way ANOVA, t-test and Scheffe's post-hoc test. Conventional groups had significantly more $Ca(OH)_2$ debris than $EndoActivator^{(R)}$, $EndoVac^{(R)}$ groups. There was no significant difference between $EndoActivator^{(R)}$ and $EndoVac^{(R)}$ groups. Groups with patency file showed more effective in removing $Ca(OH)_2$ paste than no patency groups. but. it was no significant difference. This study showed that $EndoActivator^{(R)}$ and $EndoVac^{(R)}$ systems were more effective in removing $Ca(OH)_2$ paste from the apical third of the root canal than conventional method.

• Restorative Dentistry and Endodontics
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• v.35 no.2
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• pp.88-95
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• 2010

The purpose of this study was to compare the root canal shaping ability of 4 rotary NiTi instruments in simulated root canals. For the preparation of thirty two curved root canals, Mtwo instruments using "single length"technique, and Profile, ProTaper Universal, and K3 using crown-down technique (N = 8) were used. All canal samples were prepared by reaching an apical canal size of #30. Pre- and post-instrumentation digital images were recorded and an assessment of canal shape was determined using a computer image analysis program SigmaScan Pro (Systat Software Inc., San Jose, CA, USA). The changes of the dimension of inner walls of canals, (2) the changes of the dimension of outer walls of canals, and (3) the centering ratio were measured at 7 measuring points, and then data were statistically analyzed using one-way ANOVA and Duncan's test. The results were as below; 1. The root canal shaping ability of Profile was significantly faster than that of other rotary NiTi instruments (p < 0.05). 2. The deformation and fracture of all instruments used for this study were not experienced. 3. In the degree of changes of the dimension of inner walls of canals, Profile demonstrated the lowest changes of the dimension of inner walls of canals except at the measuring points of the 1 and 2 mm (p < 0.05). However, the ProTaper Universal showed the highest changes of the dimension of inner walls of canals at all measuring points (p < 0.05). 4. In the degree of changes of the dimension of outer walls of canals, Mtwo demonstrated the lowest changse of the dimension of outer walls of canals except at the measuring point of the 1 mm (p < 0.05). However, Profile exhibited the highest changes of the dimension of outer walls of canals at the measuring points of 3 and 4 mm and ProTaper Universal and K3 showed the largest changes of the dimension of outer walls of canals at the measuring points of 1, 2, 6, and 7 mm (p < 0.05). 5. In degree of centering ratio, Profile demonstrated the least centering ratio comparing with the centering ratio shown by other NiTi instruments at the measuring points of 1, 4, 5, and 6 mm. Results suggest that in the coronal part of canal preparation, active cutting files such as ProTaper Universal may efficiently flare the canal orifice and form a better taper, and in the apical part of the canal, files which have a better centering ability such as Profile may maintain the original canal curvature and reduce the shaping time.