• Restorative Dentistry and Endodontics
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• 제42권4호
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• pp.301-308
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• 2017

Objectives: It was aimed to compare the cyclic fatigue resistances of ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG) and the effects of sterilization by autoclave on the cyclic fatigue life of nickel-titanium (NiTi) instruments. Materials and Methods: Eighty PTU, 80 PTN, and 80 PTG were included to the present study. Files were tested in a simulated canal. Each brand of the NiTi files were divided into 4 subgroups: group 1, as received condition; group 2, pre-sterilized instruments exposed to 10 times sterilization by autoclave; group 3, instruments tested were sterilized after being exposed to 25%, 50%, and 75% of the mean cycles to failure, then cycled fatigue test was performed; group 4, instruments exposed to the same experiment with group 3 without sterilization. The number of cycles to failure (NCF) was calculated. The data was statistically analyzed by using one-way analysis of variance and post hoc Tukey tests. Results: PTG showed significantly higher NCF than PTU and PTN in group 1 (p < 0.05). Sterilization significantly increased the NCF of PTN and PTG (p < 0.05) in group 2. PTN in group 3 had significantly higher cyclic fatigue resistance than PTN group 4 (p < 0.05). Also, significantly higher NCF was observed for PTG in group 2 than in groups 3 and 4 (p < 0.05). Conclusions: PTG instrument made of new gold alloy was more resistant to fatigue failure than PTN and PTU. Autoclaving increased the cyclic fatigue resistances of PTN and PTG.

• Restorative Dentistry and Endodontics
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• 제41권1호
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• pp.1-5
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• 2016

Objectives: The purpose of this study was to assess the ability of ProTaper Gold (PTG, Dentsply Maillefer) in maintaining the original profile of root canal anatomy. For that, ProTaper Universal (PTU, Dentsply Maillefer) was used as reference techniques for comparison. Materials and Methods: Twenty simulated curved canals manufactured in clear resin blocks were randomly assigned to 2 groups (n = 10) according to the system used for canal instrumentation: PTU and PTG groups, upto F2 files (25/0.08). Color stereomicroscopic images from each block were taken exactly at the same position before and after instrumentation. All image processing and data analysis were performed with an open source program (FIJI). Evaluation of canal transportation was obtained for two independent canal regions: straight and curved levels. Student's t test was used with a cut-off for significance set at ${\alpha}=5%$. Results: Instrumentation systems significantly influenced canal transportation (p < 0.0001). A significant interaction between instrumentation system and root canal level (p < 0.0001) was found. PTU and PTG systems produced similar canal transportation at the straight part, while PTG system resulted in lower canal transportation than PTU system at the curved part. Canal transportation was higher at the curved canal portion (p < 0.0001). Conclusions: PTG system produced overall less canal transportation in the curved portion when compared to PTU system.

• 구강회복응용과학지
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• 제38권4호
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• pp.213-221
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• 2022

목적: 근관 치료에 사용된 실러의 양과, 재치료용 NiTi 파일이 근관충전재의 제거 효율에 미치는 영향을 알아보고자 하였다. 연구 재료 및 방법: 발거된 소구치 중 단일 근관을 가지는 치아를 대상으로 하였다. #40/.06까지 근관 형성을 한 후, 무작위로 4 그룹으로 분류하였다. 근관충전재 중 실러가 차지하는 양을 다르게 하기 위해 그룹 별로 .06 taper 또는 .04 taper 거타퍼차를 칼슘실리케이트 실러인 Ceraseal과 함께 사용하여 single-cone 충전법으로 충전하였다. 그룹 별로 재치료용 NiTi 파일로는 ProTaper Universal Retreatment system (PTUR) 또는 Hyflex Remover (HR)를 사용하였다. 충전재 제거에 걸린 시간, 치근단 방출 잔사량, 근관 내의 충전재 잔존량을 측정하고 비교하였다. 결과: 근관치료에 사용된 실러의 양은 충전재 제거 효율에 영향을 미치지 않았다. HR 그룹은 PTUR 그룹보다 빠르게 충전재를 제거하였다. 치근단 방출 잔사량과 근관충전재 잔존량은 재치료용 NiTi 파일의 종류에 따라 유의한 차이를 보이지 않았다. 결론: 근관치료에 사용된 실러의 양은 제거 효율에 유의한 영향을 미치지 않았다. HR는 기존의 PTUR보다 빠르게 충전재를 제거했으며, 다른 제거 효율은 차이가 없었다.

• Restorative Dentistry and Endodontics
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• 제42권4호
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• pp.332-341
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• 2017

Objectives: To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR), Mtwo-R, ProTaper Next (PTN), and Twisted File Adaptive (TFA) systems. Materials and Methods: The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the negative control group. One hundred teeth were prepared, obturated, and then divided into 5 retreatment groups. The retreatment procedures were performed using the following files: PTR, Mtwo-R, PTN, TFA, and hand files. After filling material removal, apical enlargement was done using apical size 0.50 mm ProTaper Universal (PTU), Mtwo, PTN, TFA, and hand files. Digital images of the apical root surfaces were recorded before preparation, after preparation, after obturation, after filling removal, and after apical enlargement using a stereomicroscope. The images were then inspected for the presence of new apical cracks and crack propagation. Data were analyzed with ${\chi}^2$ tests using SPSS 21.0 software. Results: New cracks and crack propagation occurred in all the experimental groups during the retreatment process. Nickel-titanium rotary file systems caused significantly more apical crack formation and propagation than the hand files. The PTU system caused significantly more apical cracks than the other groups after the apical enlargement stage. Conclusions: This study showed that retreatment procedures and apical enlargement after the use of retreatment files can cause crack formation and propagation in apical dentin.

• 대한치과의사협회지
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• 제47권7호
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• pp.435-443
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• 2009

The purpose of this study was to compare the centering ratio and reduction of canal curvature according to the preparation sizes of #30, #40 and #50 using three rotary NiTi instruments which have different shaft tapers. Seventy-two simulated root canals in clear resin blocks (Endo Training Bloc; Dentsply Maillefer, Ballaigues, Switzerland) were divided as following 3 groups according to the file system; the 24 canal blocks prepared with each of ProTaper Universal system (Group P), LightSpeed eXtra system (Group L), and K3 (Group K). The pre- and post-instrumented root canals were scanned and superimposed to evaluate and calculate the centering ratio and reduction of canal curvature. Mean scores of each group were statistically analyzed using one-way ANOV A and Duncan's multiple range test for post-hoc comparison. The results were as followings: 1. Group L showed better centering ratio, followed by K and P. And all experimental groups generally showed increasing tendency of centering ratio as the apical size was increasing from #30 to #50, except at 1 mm level of group P where showed reducing tendency of centering ratio. The smaller the ratio, the better the instrument remained centered in the canal. 2. Group P showed more decrease of canal curvature at all apical shaping size (p < 0.05). Under the conditions of this study, the shaft design could affect the quality of canal shaping and the smooth taperless flexible (LightSpeed) shaft design was capable of preparing canals with good morphological characteristics in curved canals.

• 구강회복응용과학지
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• 제27권1호
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• pp.99-107
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• 2011

비외과적 재근관치료의 주된 목표는 치근주변의 치유를 위하여 근관 공간을 완전히 멸균하는 것이며, 이 목표를 달성하기 위해서는 이전 충전물질의 완전한 제거가 요구된다. 전통적으로 근관충전물질의 제거는 스테인리스스틸 수기구를 통해서 이루어져 왔으며 이는 시간과 노력이 많이 소요되는 작업이다. 최근 보다 효율적인 근관충전물질의 제거를 위해 재치료용 회전식 NiTi 기구가 소개되었다. 이 연구에서는 만곡된 근관에서의 스테인리스스틸 수기구, ProTaper Universal Retreatment (Dentsply Maillefer, Ballaigues, Switzerland), Mtwo retreatment (Sweden & Martina, Padova, Italy)의 gutta-percha 제거 효율을 비교하였다. 재치료 후 근관 내 남겨진 gutta-percha의 양은 실험군 사이에 유의한 차이가 발견되지 않았다. 하지만 재치료에 소요된 시간은 재치료용 회전식 NiTi 기구를 이용한 실험군에서 더 적게 소요되는 것으로 나타났다.

• Restorative Dentistry and Endodontics
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• 제33권4호
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• pp.377-388
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• 2008

이 연구에서는 다양한 부식 환경하에서 니켈티타늄 파일에 대한 부식 경향을 전기화학적 검사와 시각적 검사를 이용해 비교 평가하였다. 각 45개의 21 mm ProTaper Universal 52와 21 mm #25/0.06의 Hero642 file을 기계적 하중 여부, 저장 용액(증류수 및 차아염소산나트륨), 저장 온도(22$^{\circ}C$ 및 55$^{\circ}C$), 파일 종류에 따라 18개의 그룹(n = 5)으로 나누었다. 40개의 발거 치아 근관을 성형한 후 18시간 동안 저장 용액에 조건에 따라 보관하였다. 부식 산물의 생성 여부나 변색 등을 관찰하고 주사전자현미경을 이용해 각 시편을 다양한 배율에서 관찰하였으며 에너지 분산형 X선 분광기로 성분 분석을 하였다 전기화학적분극시험을 통하여 새 파일과 근관 성형에 사용한 파일의 부식저항성을 검사하였다. 본 실험 조건하에서는 저장 용액의 종류와 보관 온도가 니켈 티타늄 파일의 부식에 영향을 주는 것으로 나타났다. 또한 이종 금속이 존재하는 경우 갈바닉 부식의 영향으로 인해니켈 티타늄 파일의 부식 경향이 증가할 수도 있음을 보였다.

• Restorative Dentistry and Endodontics
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• 제41권3호
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• pp.176-181
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• 2016

Objectives: This study aimed to compare two nickel-titanium systems (rotary vs. reciprocating) for their acceptance by undergraduate students who experienced nickel-titanium (NiTi) instruments for the first time. Materials and Methods: Eighty-one sophomore dental students were first taught on manual root canal preparation with stainless-steel files. After that, they were instructed on the use of ProTaper Universal system (PTU, Dentsply Maillefer), then the WaveOne (WO, Dentsply Maillefer). They practiced with each system on 2 extracted molars, before using those files to shape the buccal or mesial canals of additional first molars. A questionnaire was completed after using each file system, seeking students' perception about 'Ease of use', 'Flexibility', 'Cutting-efficiency', 'Screwing-effect', 'Feeling-safety', and 'Instrumentation-time' of the NiTi files, relative to stainless-steel instrumentation, on a 5-point Likert-type scale. They were also requested to indicate their preference between the two systems. Data was compared between groups using t-test, and with Chi-square test for correlation of each perception value with the preferred choice (p = 0.05). Results: Among the 81 students, 55 indicated their preferred file system as WO and 22 as PTU. All scores were greater than 4 (better) for both systems, compared with stainless-steel files, except for 'Screwing-effect' for PTU. The scores for WO in the categories of 'Flexibility', 'Screwing-effect', and 'Feeling-safety' were significantly higher scores than those of PTU. A significant association between the 'Screwing-effect' and students' preference for WO was observed. Conclusions: Novice operators preferred nickel-titanium instruments to stainless-steel, and majority of them opted for reciprocating file instead of continuous rotating system.

• Restorative Dentistry and Endodontics
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• 제42권3호
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• pp.216-223
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• 2017

Objectives: The aim of this study was to compare the mechanical properties of various nickel-titanium (NiTi) files with similar tapers and cross-sectional areas depending on whether they were surface-treated. Materials and Methods: Three NiTi file systems with a similar convex triangular cross-section and the same ISO #25 tip size were selected for this study: G6 (G6), ProTaper Universal (PTU), and Dia-PT (DPT). To test torsional resistance, 5 mm of the straightened file's tip was fixed between polycarbonate blocks (n = 15/group) and continuous clockwise rotation until fracture was conducted using a customized device. To evaluate cyclic fatigue resistance, files were rotated in an artificial curved canal until fracture in a dynamic mode (n = 15/group). The torsional data were analyzed using 1-way analysis of variance and the Tukey post-hoc comparison test, while the cyclic fatigue data were analyzed using the Mann-Whitney U test at a significance level of 95%. Results: PTU showed significantly greater toughness, followed by DPT and G6 (p < 0.05). G6 showed the lowest resistance in ultimate torsional strength, while it showed a higher fracture angle than the other files (p < 0.05). In the cyclic fatigue test, DPT showed a significantly higher number of cycles to failure than PTU or G6 (p < 0.05). Conclusions: Within the limitations of this study, it can be concluded that the torsional resistance of NiTi files was affected by the cross-sectional area, while the cyclic fatigue resistance of NiTi files was influenced by the surface treatment.

• 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.