• Restorative Dentistry and Endodontics
• /
• 제42권3호
• /
• pp.224-231
• /
• 2017

Objectives: To determine the actual revolutions per minute (rpm) values and compare the cyclic fatigue life of Reciproc (RPC, VDW GmbH), WaveOne (WO, Dentsply Maillefer), and TF Adaptive (TFA, Axis/SybronEndo) nickel-titanium (NiTi) file systems using high-speed camera. Materials and Methods: Twenty RPC R25 (25/0.08), 20 WO Primary (25/0.08), and 20 TFA ML 1 (25/0.08) files were employed in the present study. The cyclic fatigue tests were performed using a dynamic cyclic fatigue testing device, which has an artificial stainless steel canal with a $60^{\circ}$ angle of curvature and a 5-mm radius of curvature. The files were divided into 3 groups (group 1, RPC R25 [RPC]; group 2, WO Primary [WO]; group 3, TF Adaptive ML 1 [TFA]). All the instruments were rotated until fracture during the cyclic fatigue test and slow-motion videos were captured using high-speed camera. The number of cycles to failure (NCF) was calculated. The data were analyzed statistically using one-way analysis of variance (ANOVA, p < 0.05). Results: The slow-motion videos were indicated that rpm values of the RPC, WO, and TFA groups were 180, 210, and 425, respectively. RPC ($3,464.45{\pm}487.58$) and WO ($3,257.63{\pm}556.39$) groups had significantly longer cyclic fatigue life compared with TFA ($1,634.46{\pm}300.03$) group (p < 0.05). There was no significant difference in the mean length of the fractured fragments. Conclusions: Within the limitation of the present study, RPC and WO NiTi files showed significantly longer cyclic fatigue life than TFA NiTi file.

• Restorative Dentistry and Endodontics
• /
• 제36권1호
• /
• pp.1-11
• /
• 2011

서론: 이 문헌의 목적은 Nickel-titanium (NiTi) 전동 파일의 기계적 형태적 양상과 이에 의한 임상적 연관성을 고찰하는 것이다. NiTi 전동 파일은 다양한 고유의 형태로 시장에 소개되었고 경쟁 상품에 비해서 근관 성형에 더 나은 능력을 가졌다고 주장하고 있다. 본론: 이 문헌에서는 NiTi 전동 파일의 형태(예. 팁, 테이퍼, helical angle 등)와 파일의 임상 적용 성과 사이의 가능한 상관관계를 다음과 같이 다룬다; - NiTi 전동 파일의 파절 양상 - 비활성 파일팁과 glide path - 파일 경사도와 임상 효과 - 파일 횡단면적과 임상 효과 - 열처리와 표면 특성 - Screw-in 효과와 치근 상아질의 유지 - Screw-in 효과를 줄이기 위한 고안 결론: 이상의 내용을 바탕으로, 임상가는 다양한 NiTi 전동 기구를 사용함에 있어 임상 상황에 적절한 장점을 고려하여 선택하고 사용할 수 있는 도움을 받을 수 있을 것이다.

• Restorative Dentistry and Endodontics
• /
• 제46권1호
• /
• pp.6.1-6.10
• /
• 2021

Objectives: The aim of this study was to evaluate the corrosion resistance of heat-treated (Reciproc and WaveOne) and non-heat-treated (ProTaper and Mtwo) superelastic nickel-titanium endodontic files when immersed in a 5.25% sodium hypochlorite solution. Materials and Methods: Anodic polarization curves were obtained with potential sweeps that began at the open circuit potential or corrosion potential (E_corr). The pitting potential (E_pit) was identified on the anodic polarization curve as the potential at which a sudden increase in current was observed. The micromorphology of the 28 tested files was analyzed before and after the electrochemical assay using scanning electron microscope (SEM). The data were analyzed using 1-way analysis of variance with the post hoc Bonferroni test (for E_corr) and the Student t-test for independent samples (for E_pit). Results: The mean E_corr values were 0.506 V for ProTaper, 0.348 V for Mtwo, 0.542 V for Reciproc, and 0.321 V for WaveOne files. Only WaveOne and Protaper files exhibited pitting corrosion, with E_pit values of 0.879 V and 0.904 V, respectively. On the SEM images of the ProTaper and WaveOne files, cavities suggestive of pitting corrosion were detected. Conclusions: Signs of corrosion were observed in both heat-treated and non-heat-treated files. Of the evaluated files, WaveOne (a heat-treated file) and ProTaper (a non-heat-treated file) exhibited the lowest corrosion resistance.

• Restorative Dentistry and Endodontics
• /
• 제23권1호
• /
• pp.94-109
• /
• 1998

The purpose of this study was to evaluate the effect of materials and sizes of files on canal transportation in a curved canal. The stress and the strain energy of files of two kinds of materials (stainless steel and NiTi) and five sizes (No. 20, 25, 30, 35 and 40) in a curved canal were analyzed by a finite element program, NASTRAN. Curved canals in transparent resin blocks were instrumented with the 10 kinds of files, and the degree of canal transportation obtained by double exposure technique of photography was compared with the analysis by the finite element method. The results were as follows : 1. The stress of a file in a curved canal increased from the file body to the file tip. 2. The stress of a stainless steel file was about 2.5 times greater than that of a same-sized NiTi file. 3. The stress distributions of files of an identical material were the same, and the strain energies of files of an identical material increased as the size of files increased. 4. The strain energy of a No. 35 NiTi file was about the same as that of a No. 20 stainless steel file. 5. The degree of canal transportation by a stainless steel file was greater than that by a same-sized NiTi file. The degree of canal transportation generally increased as the size of a file increased. 6. The degree of canal transportation of a No. 35 NiTi file was about the same as that of a No. 20 stainless steel file.

• Restorative Dentistry and Endodontics
• /
• 제25권3호
• /
• pp.381-389
• /
• 2000

Lateral condensation with gutta-percha and sealer has been shown to provide an excellent apical seal; however, the lateral condensation technique has demonstrated less favorable apical leakage results in curved canals when compared with straight canals. Placement of endodontic spreaders to within 1 to 2mm of the root canal working length has been advocated for optimum gutta-percha obturation. Due to their stiffness, stainless-steel(SS) spreaders will often fail to achieve this position in curved canals. Newly marketed nickel-titanium(NT) spreaders may offer an advantage in this regard due to the increased flexibility of these instruments. The purpose of this study was to evaluate the effect of NT finger spreader on the sealing ability in lateral condensation technique, compared with conventional SS finger spreader. Twenty four standardized resin models simulating curved canals(30 degree) were randomly placed into 2 groups and instrumented to a #30 master apical file size with Ni-Ti Profile .04 taper series using step down technique. Each groups was obturated with standardized gutta-percha cone by standard lateral condensation technique using SS finger spreader, NT finger spreader. And then, each model was sectioned horizontally with microtome at 1, 2, 3, 4, 5mm levels from the apex. At each of 5 levels, ratio of the area of gutta-percha was obtained by calculating the area of gutta-percha to the total area of the canal. The data collected were then analyzed statistically using a t test for independent samples. The results as follows ; 1. The total mean ratio of area of gutta-percha was 89.20${\pm}$7.00(%) for SS spreader group. 92.20${\pm}$5.17(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). 2. At 3mm level, the mean ratio of area of gutta-percha was 88.32${\pm}$5.41(%) for SS spreader group, 95.25${\pm}$2.60(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). At 1,2,4mm levels, NT spreader group showed greater mean ratio of area of gutta-percha than SS spreader group, too. But there was no statistically significant difference. 3. At 5mm level, the mean ratio of area of gutta-percha was 91.83${\pm}$3.42(%) for SS spreader group, 87.91${\pm}$3.68(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). This study concluded that the NT spreader demonstrated somewhat favorable apical sealing effect than SS spreader in prepared curved canals. The clinical use of NT spreaders may enhance our ability to create better apical seals in curved canals, but further studies in this area will help clarify some of the remaining areas with which practitioners are concerned, such as compaction forces exerted by NT spreaders.

• 구강회복응용과학지
• /
• 제30권2호
• /
• pp.121-130
• /
• 2014

목적: Reciprocating 파일인 WaveOne과 continuous rotary 파일인 ProTaper와 ProFile로 근관 형성시 상아질 벽의 표면성상과 상아질 삭편 크기와 도말층 제거 효과를 비교하였다. 연구 재료 및 방법: 60개 단근치를 ProFile, ProTaper, WaveOne으로 성형 후 근관이 보이도록 grinding 하였다. 근관 성형 동안 상아질 삭편을 모아 건조하였다. Scanning electron microscope으로 상아질 삭편 크기와 근관 표면의 불규칙성과 도말층을 관찰하였다. 결과: 표면 함요부의 범위는 ProFile, ProTaper 그리고 WaveOne에서 $150{\mu}m$, $70{\mu}m$, 그리고 $80{\mu}m$의 범위 내에서 관찰되었다. 상아질 삭편의 크기는 ProFile, ProTaper 그리고 WaveOne에서 $7{\mu}m$, $6.5{\mu}m$, 그리고$4{\mu}m$의 범위 내에서 관찰되었다. 도말층은 WaveOne의 중간 1/3과 근단 1/3에서 유의하게 더 많이 관찰되었다. 결론: WaveOne은 중간 1/3과 치근단 1/3의 도말층 제거 효과를 제외하고, ProFile과 ProTaper와 근관 표면 성상과 상아질 삭편에서 큰 차이가 없는 것으로 사료된다.

• Restorative Dentistry and Endodontics
• /
• 제39권4호
• /
• pp.270-275
• /
• 2014

Objectives: This study compared the mechanical properties of various instruments for canal exploration and glide-path preparations. Materials and Methods: The buckling resistance, bending stiffness, ultimate torsional strength, and fracture angle under torsional load were compared for C+ file (CP, Dentsply Maillefer), M access K-file (MA, Dentsply Maillefer), Mani K-file (MN, Mani), and NiTiFlex K-file (NT, Dentsply Maillefer). The files of ISO size #15 and a shaft length of 25 mm were selected. For measuring buckling resistance (n = 10), the files were loaded in the axial direction of the shaft, and the maximum load was measured during the files' deflection. The files (n = 10) were fixed at 3 mm from the tip and then bent $45^{\circ}$ with respect to their long axis, while the bending force was recorded by a load cell. For measuring the torsional properties, the files (n = 10) were also fixed at 3 mm, and clockwise rotations (2 rpm) were applied to the files in a straight state. The torsional load and the distortion angle were recorded until the files succumbed to the torque. Results: The CP was shown to require the highest load to buckle and bend the files, and the NT showed the least. While MA and MN showed similar buckling resistances, MN showed higher bending stiffness than MA. The NT had the lowest bending stiffness and ultimate torsional strength (p < 0.05). Conclusions: The tested instruments showed different mechanical properties depending on the evaluated parameters. CP and NT files were revealed to be the stiffest and the most flexible instruments, respectively.

• Restorative Dentistry and Endodontics
• /
• 제42권4호
• /
• pp.316-323
• /
• 2017

Objectives: This study compared the amount of apically extruded bacteria during the glide-path preparation by using multi-file and single-file glide-path establishing nickel-titanium (NiTi) rotary systems. Materials and Methods: Sixty mandibular first molar teeth were used to prepare the test apparatus. They were decoronated, blocked into glass vials, sterilized in ethylene oxide gas, infected with a pure culture of Enterococcus faecalis, randomly assigned to 5 experimental groups, and then prepared using manual stainless-steel files (group KF) and glide-path establishing NiTi rotary files (group PF with PathFiles, group GF with G-Files, group PG with ProGlider, and group OG with One G). At the end of canal preparation, 0.01 mL NaCl solution was taken from the experimental vials. The suspension was plated on brain heart infusion agar and colonies of bacteria were counted, and the results were given as number of colony-forming units (CFU). Results: The manual instrumentation technique tested in group KF extruded the highest number of bacteria compared to the other 4 groups (p < 0.05). The 4 groups using rotary glide-path establishing instruments extruded similar amounts of bacteria. Conclusions: All glide-path establishment instrument systems tested caused a measurable apical extrusion of bacteria. The manual glide-path preparation showed the highest number of bacteria extruded compared to the other NiTi glide-path establishing instruments.

• Restorative Dentistry and Endodontics
• /
• 제48권4호
• /
• pp.36.1-36.15
• /
• 2023

Objectives: This study aimed to compare the effectiveness of a single-file reciprocating system (WaveOne Gold, WOG) and a multi-file rotary system (ProTaper Universal Retreatment, PTUR) in removing canal filling from severely curved canals and to evaluate the possible adjunctive effects of XP-Endo Finisher (XPF), the Self-Adjusting File (SAF), and an erbium, chromium: yttrium, scandium, gallium garnet (Er,Cr:YSGG) laser using microcomputed tomography (µCT). Materials and Methods: Sixty-six curved mandibular molars were divided into 2 groups based on the retreatment technique and then into 3 based on the supplementary method. The residual filling volumes and root canals were evaluated with µCT before and after retreatment, and after the supplementary steps. The data were statistically analyzed with the t-test, Mann-Whitney U test, analysis of covariance, and factorial analysis of variance (p < 0.05). Results: PTUR and WOG showed no significant difference in removing filling materials (p > 0.05). The supplementary techniques were significantly more effective than reciprocating or rotary systems only (p < 0.01). The supplementary steps showed no significant differences in canal filling removal effectiveness (p > 0.05), but XPF showed less dentin reduction than the SAF and Er,Cr:YSGG laser (p < 0.01). Conclusions: The supplementary methods significantly decreased the volume of residual filling materials. XPF caused minimal changes in root canal volume and might be preferred for retreatment in curved root canals. Supplementary approaches after retreatment procedures may improve root canal cleanliness.

• Restorative Dentistry and Endodontics
• /
• 제35권5호
• /
• pp.380-386
• /
• 2010

연구목적: 니켈-티타늄 금속을 근관치료기구에 도입함으로써 근관형성과정이 매우 단순화되었다. 그러나 이러한 새로운 기구는 단점도 함께 가지고 있는데 그 중 하나가 근관내로 기구가 빨려 들어가는 경향이다. 본 연구에서는 니켈-티타늄 전동파일의 경사도가 screw-in effect에 미치는 영향을 평가하고자 하였다. 연구 재료 및 방법: 총 20개의 S-자형 투명레진블록 (Dentsply-Maillefer) 근관에서 두 군으로 나누어 실험하였는데 Profile군에서는 0.02, 0.04 그리고 0.06 경사도의 Profile (Dentsply-Maillefer)과 0.08, 0.10 그리고 0.12의 경사도의 GT Rotary file (Dentsply-Maillefer)을 사용하였고 K3군에서는 같은 경사도의 K3 file SybronEndo)을 사용하였으며, 분당 300회전의 일정한 속도에서 단일 pecking 동작으로 기구조작을 하였다. 특수한 장치를 고안하였으며 장치내 dynamometer를 이용하여 screw-in effect를 측정하여 one-way ANOVA로 통계처리하고 Tuckey's multiple range test로 사후검정하였다. 결과: Profile 군에서는 큰 경사도의 기구가 더 큰 screw-in force를 나타내었고 (p < 0.05), K3군에서는 0.08, 0.10. 및 0.12 경사도의 기구가 0.04 경사도의 기구에 비해, 0.08 및 0.12 경사도의 기구가 0.06 경사도의 기구에 비해 더 큰 screw-in force를 나타내었다 (p < 0.05). 결론: 기구의 경사도가 클수록 screw-in force가 많이 발생하는 것으로 생각되며, 경사도가 큰 전동화일을 사용시에는 screw-in force를 억제하기 위해 더 많은 주의가 요구될 것으로 생각된다.