Evaluation of the Efficiency of a New File Removal System in Comparison With Two Conventional Systems

doi:10.1016/j.joen.2006.12.018

Journal of Endodontics

Volume 33, Issue 5, May 2007, Pages 585-588

https://doi.org/10.1016/j.joen.2006.12.018 Get rights and content

Abstract

A novel file-removal system (FRS) was designed to address weak points of conventional file-removal methods. The purpose of this study was to compare file-removal time and dentin removal rates among the FRS, the Masserann kit (Micro-Mega, Besancon, France), and an ultrasonic file-removal method. Ninety extracted mandibular incisors with separated nickel titanium files were divided into 3 groups of 30 teeth each. Groups 1, 2, and 3 had file-removal attempts made by using the Masserann kit, a CPR-7 titanium ultrasonic tip (Obtura-Spartan Corp., Fenton, MO), and the FRS, respectively. Each group had three operators removing the separated files. Pre-/postoperative digital radiographs were downloaded into image analyzing software that calculated the amount of dentin removed. The FRS needed less time and had less dentin loss than the others (p < 0.05). There were statistical differences between the experienced operator and less experienced operators regarding the file-removal time and the dentin removal rates (p < 0.05).

Section snippets

Materials and Methods

Ninety extracted human mandibular incisors with straight roots were used in the study. It was visually recognized that all the experimental teeth had completely developed root apices. The clinical crowns were removed, and conventional access cavities were prepared with high-speed diamond burs. The working length was established by inserting a #15 K file into the canal until the tip was visualized at the apex. The root canals were prepared to the canal terminus by using 25-mm long greater taper

Results

Ninety of 98 separated files consumed in all the groups were successfully removed. The number of unsuccessful cases and causes for failure are listed in Table 1A. Mean file-removal time in minutes, mean dentin removal rates (%) of MD and LL directions with standard deviations and multiple comparisons among the operators and among the experimental groups were determined by using Fisher PLSD and are listed in TABLE 2, TABLE 3, TABLE 4. Representative samples in each group are shown in Figure 2.

Discussion

In the results, there were no statistically significant differences between operators 1 and 2 in both dentin removal rates and working time. However, between operator 3 and the other operators, there were significant differences in the working time and the dentin removal rate in the LL direction. The results showed operator 3 had the longest file-removal time and the lowest dentin removal rate among all the operators in each group, which shows that operator 3 was very careful not to sacrifice

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Cited by (39)

Comparative Evaluation of a Dynamic Navigation System versus a Three-dimensional Microscope in Retrieving Separated Endodontic Files: An In Vitro Study
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This study aimed to compare the effectiveness of a dynamic navigation system and a three-dimensional microscope in retrieving broken rotary Nickel-Titanium files when using trepan burs and the extractor system.
Thirty maxillary first bicuspids with 60 separate roots were split into 2 comparable groups based on a comprehensive cone beam computed tomography analysis of the root length and curvature. After standardized access opening, glide paths, and patency attainment with the K file (sizes 10 and 15), the teeth were arranged on 3D models (three per quadrant, six per model). Subsequently, controlled-memory heat-treated Nickel-Titanium rotary files (#25/0.04) were notched 4 mm from the tips and fractured at the apical third of the roots. The C-FR1 Endo file removal system was employed under both guidance to retrieve the fragments, and the success rate, canal aberration, treatment time, and volumetric changes were measured. The statistical analysis was performed using IBM SPSS software at a significance level of 0.05.
The microscope-guided group had a higher success rate than the dynamic navigation system guidance, but the difference was insignificant (P > .05). In addition, the microscope-guided drills resulted in a substantially lower proportion of canal aberration, shorter time to retrieve the fragments and less change in the root canal volume (P < .05).
Although dynamically guided trephining with the extractor can retrieve separated instruments, it is inferior to three-dimensional microscope guidance regarding treatment time, procedural errors, and volume change.
Outcome of Nonsurgical Root Canal Retreatment Procedures Obturated with Warm Gutta-percha Techniques: A Longitudinal Clinical Study
2023, Journal of Endodontics
To evaluate the success rate of nonsurgical root canal retreatment at the 2–3-year follow-up and identify the possible prognostic factors.
Patients who underwent root canal retreatment at a university dental clinic were contacted for clinical and radiographic follow-up. The retreatment outcomes in these cases were based on clinical signs, symptoms, and radiographic criteria. Inter- and intraexaminer concordances were calculated using Cohen's kappa coefficient. The retreatment outcome was dichotomized into success or failure according to strict and loose criteria. The radiographic success criteria consisted of complete resolution or absence of a periapical lesion (strict criteria) or a reduction in the size of an existing periapical lesion at recall (loose criteria). χ² tests were used to evaluate possible variables associated with retreatment outcomes (age, sex, tooth type, location, contact points, periapical status, quality of previous and final root canal filling, previous and final restoration, number of visits, and complications).
Overall, 129 teeth (113 patients) were included in the final evaluation. The success rate was 80.6% under strict criteria and 93% under loose criteria. Molars, teeth with an initially higher periapical index score, and teeth with >5 mm periapical radiolucency had a lower success rate according to the strict criteria model (P < .05). When the loose success criteria were used, teeth with larger (>5 mm) periapical lesions and those that had been perforated during retreatment showed a lower success rate (P < .05).
The present study demonstrated that nonsurgical root canal retreatment is a highly successful procedure after an observation period of 2–3 years. Treatment success is primarily affected by the presence of large periapical lesions.
Factors Affecting the Removal Time of Separated Instruments
2021, Journal of Endodontics
Citation Excerpt :
This outcome suggests that SIs visible under a DOM can be predictably removed with ultrasonics alone using a single standardized retrieval protocol (Fig. 5A–Q). Other ultrasonic removal techniques requiring 3 to over 60 minutes have been reported4,21,24. Treatment variables that may affect file removal predictability include nonstandardized protocols11,25–30, SI canal location, visibility of the separated instrument, root canal diameter, degree of canal curvature, operator experience, operator fatigue, and the length of the retained fragment4,6,8,10,12,31–33.
Separated endodontic instruments may adversely affect the outcome of endodontic treatment. The combination of ultrasonic techniques and dental operating microscopes appears to be effective in the removal of separated instruments compared with more randomized techniques. This study evaluated the roles of root canal curvature and separated instrument length on the time needed to loosen and retrieve the instrument fragments.
The retrieval procedures of 128 separated instruments referred to a private endodontic practice for retreatment by general practitioners were evaluated in patients who were monitored for a minimum of 6 months. Preoperative cone-beam computed tomographic images were used to measure separated instrument lengths in relation to the degrees of canal curvatures. Ultrasonic instruments were used in the initial phase to remove the tooth structure and to loosen the fractured instrument. In the second phase, ultrasonic instruments, wire loops, or XP Shapers (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) were used for fragment removal. The time periods for all procedures were recorded. Statistical analysis was completed applying log-normal regression, structural equation modeling, and linear regression using Stata Version 14.2 software (StataCorp LLC, College Station, TX).
All separated instruments were successfully retrieved. Using the protocol in this study, 89.8% of the instruments were removed using ultrasonic instruments alone with a mean time of 221 seconds. The instrument removal time was dependent on both the instrument length and the root canal curvature. Additionally, preparation times were proportionately longer with increasing separated instrument lengths when the loop device was required.
The preparation phase appears to have an important role in the retrieval of separated instruments. Preparation times for both non-loop and loop groups demonstrate that length and curvature are independent predictors of the log-transformed time. Generally, procedure times were extended with increasing file lengths and higher degrees of canal curvature.
Tube Technique with Light-curing Composite for Removing Fractured Root Canal Instruments: Influence of Polymerization Cycles and Mechanical Exposure
2020, Journal of Endodontics
The purpose of this study was to investigate the influence of both polymerization cycles and mechanical exposure procedures on the adhesion of instrument fragments using a modified tube technique with a light-curing composite.
Eighty Mtwo instruments (size 15.05; VDW, Munich, Germany) were cut at a diameter of 35/100 mm and clamped in a vice with an overlap of 2 mm. Matching cannulas were filled with SDR composite (Dentsply, York, PA) and placed over the instruments. Prime & Bond Active (Dentsply Sirona, Bensheim, Germany) was used as the bonding material. Glass fiber was inserted from the opposite side into the cannula, and 1, 2, 4, or 6 polymerization cycles of 30 seconds were applied (800 mW/mm²) (n = 20/group). Sixty further identical instruments (n = 20/group) were divided into the following groups: group 1, cut at 10 mm and left unprepared (taper = 5%); group 2, parallelized using diamond instruments (taper = 0%); and group 3, prepared in a way that an inverted conical taper resulted (taper = 2%). Polymerization was performed for 2 minutes. The failure load and mode of failure were determined using a tensile testing device (2 mm/min). Data were statistically analyzed using the Kruskal-Wallis or chi-square test.
The failure load increased significantly with the number of polymerization cycles (P < .0001). More than 4 polymerization cycles had no further benefit (P > .05). The failure load in the inverted conical group was significantly lower (P < .0001) compared with the parallel and the unprepared groups. Adhesive failure was significantly more frequent in groups 2 and 3 (20/20) than in group 1 (16/20) (P < .05).
Both the number of polymerization cycles and the mechanical exposure procedures had a significant impact on the adhesive force when using the tube technique.
Accuracy of Cone-beam Computed Tomography in Measuring Dentin Thickness and Its Potential of Predicting the Remaining Dentin Thickness after Removing Fractured Instruments
2017, Journal of Endodontics
The purpose of this study was to evaluate the accuracy of cone-beam computed tomographic (CBCT) to measure dentin thickness and its potential of predicting the remaining dentin thickness after the removal of fractured instrument fragments.
Twenty-three human mandibular molars were selected, and 4-mm portions of #25/.06 taper K3 files (SybronEndo, Orange, CA) were fractured in mesial canals. The teeth were then scanned using a micro–computed tomographic (micro-CT) system and a CBCT unit. Dentin thickness was measured and compared between both micro-CT and CBCT images to study the accuracy of CBCT readings. Then, the process of removing the fragments was simulated in CBCT images using the MeVisLab package (MeVis Research, Bremen, Germany); the predicted minimal remaining dentin thickness after removal was measured in different layers using VGStudio MAX software (Volume Graphics, Heidelberg, Germany). Data were compared with the actual minimal remaining dentin thickness acquired from micro-CT images, which were scanned after removing fractured instruments using the microtrepan technique. The results were analyzed statistically using intraclass correlation coefficients (ICCs) and a forecasting regression model analysis.
The ICC for the dentin thickness was 0.988. The forecasting regression model of CBCT imaging estimating dentin thickness was micro-CT imaging = 15.835 + 1.080*CBCT, R² = 0.963. The ICC for the remaining dentin thickness was 0.975 (P < .001). The forecasting regression model of CBCT imaging forecasting remaining dentin thickness was micro-CT imaging = 147.999 + 0.879*adjusted CBCT, R² = 0.906.
The study showed that CBCT imaging could measure dentin thickness accurately. Furthermore, using CBCT images, it is reliable and feasible to forecast the remaining dentin thickness after simulated instrument removal.
Evaluation of Two Trephine Techniques for Removal of Fractured Rotary Nickel-titanium Instruments from Root Canals
2017, Journal of Endodontics
Citation Excerpt :
Twenty-one teeth (42 canals) with mesiobuccal and mesiolingual canals that were symmetric in shape, size, and curvature were selected for the study. Size 25/.06 K3 NiTi instruments (SybronEndo, Orange, CA) with a 4-mm apical segment were fractured in the mesial canals, 5 mm apically from the canal orifice as described in a previous study (6). Instruments were notched to a depth of half the instrument thickness at 4 mm from the tip by using a low-speed 0.3-mm-thick diamond disk.
The aim of this in vitro study was to evaluate the effects on root dentin of 2 trephining techniques using an ultrasonic tip or a trepan bur in the mesial canals of mandibular molars during attempts to remove fractured file fragments using micro–computed tomographic imaging.
Twenty-one teeth with a similar anatomic configuration in mesial (buccal and lingual) canals were selected. A 4-mm apical segment of K3 file size 25/.06 was fractured in each mesiobuccal and mesiolingual canal 5 mm apically from the canal orifice. A staging platform was prepared at the coronal aspect of the broken instrument followed by either ultrasonics or a new trepan bur technique to expose a 1- to 1.5-mm length of the fragment. If the broken instrument could not be removed by exposing it either by ultrasound or the trepan bur, a microtube device was used to attach to and withdraw the fragment. Micro-CT scanning was performed before and after removing the broken instrument. Canal volume, diameter, and furcal root dentin thickness were measured by using image analysis software. The time required for the removal of the instrument fragments was recorded. The result was statistically analyzed using the paired t test.
The trepan bur technique had significantly less impact on canal volume, diameter, and furcal root dentin thickness change than the ultrasonic technique (P < .001). The time consumed for successful removal of the fragments was significantly less in the trepan bur group (8.9 ± 3.5 minutes) than in the ultrasonic group (25 ± 11.9 minutes) (P < .001).
A new small-sized trepan bur technique was superior to the use of ultrasound with regard to the amount of dentin removed and the speed in the removal of fractured instruments from root canals.

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Basic research—technologyEvaluation of the Efficiency of a New File Removal System in Comparison With Two Conventional Systems

Abstract

Section snippets

Materials and Methods

Results

Discussion

J Endod

J Am Dent Assoc

J Endod

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

J Endod

J Endod

J Endod

J Endod

Basic research—technology
Evaluation of the Efficiency of a New File Removal System in Comparison With Two Conventional Systems