A new device to test cutting efficiency of mechanical endodontic instruments (original) (raw)
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Measurement of the cutting efficiency of endodontic instruments: A new concept
Journal of Endodontics, 1996
The cutting efficiency of endodontic instruments was measured using an original experimental technique that incorporates new concepts to simulate clinical conditions. Five designs of #1SO 030 endodontic instruments, K-reamer (Maillefer), Flexofile (Maillefer), Helifile (Micro-mega), K-flex (Kerr), and Unifile (De Trey), were chosen and their cutting efficiency assessed at their full working length of 16 mm on two Plexiglas parallelepipeds tilted to follow the 2% conicity of the instruments. For each instrument, four series of 25 cuts were carried out and each cut made on a new flat, smooth Plexiglas surface with an even hardness of 33 VHN. Instruments were tested under a simulated clinical condition of a quarter clockwise turn ROTARY MOTION followed by a PULL ACTION at 16 mm/s rate, with a fixed load on the instrument of 325 g. Water irrigation at a rate of 85 ml/s was supplied before each procedure. Cutting efficiency was evaluated in terms of mass of Plexiglas cut (using a Mettler analytic balance with accuracy of 3 x 10-5 g) per unit of energy used by the instrument, i.e. mg/J. Unifile was found to have the best cutting efficiency of 0.80-4-0.01 (Mean _+ SD) and lowest cutting efficiency loss followed by Flexofile 0.70 __. 0.03 then Helifile 0.36-0.01 then K-flex 0.51-0.07. K-reamer was found to have the lowest cutting efficiency of 0.16 ___ 0.05. The cutting, reaming, and machining efficiencies of various endodontic instruments have been evaluated with a wide variety of techniques over the past few years using various experimental devices. The A.D.A. (1) has established the specifications for sizes, taper, angle of the tip, dimensions at the beginning and at the end of the working head, and overall length but has not yet established any specific test for cutting efficiency of endodontic instruments. This absence of a standard method to measure cutting efficiency of endodontic instruments has led to the emergence of several techniques. 651 Research over the years has drawn attention to the importance of the configuration and cross-sectional shape of instrument (2) and tip design (3, 4) to the cutting efficiency. The significance of the helical angle, defined as being "the angle between cutting edge & long axis of'the instrument," on cutting efficiency has (5) led to
Journal of endodontics, 1988
In this study the cutting efficiency of three hybrid designs of endodontic instruments were compared with traditional K-type and H-type files for their ability to enlarge standardized artificial root canals. Sizes #15 through 30 instruments were tested in a clinical manner by serial preparation using a circumferential filing motion as the method of canal enlargement. The relative cutting ability of each group was evaluated in terms of the mean specimen weight loss following sedal preparation. The cutting efficiency of each group was reported as the rate of canal enlargement, based on the mean specimen weight loss versus time. Significantly greater cutting efficiency occurred with the newly designed S file and traditional Hedstrom files over other types of hand instruments. REVIEW OF THE LITERATURE Since the introduction of the K file at the beginning of the 20th century, the design and manufacture of endodontic instruments have remained essentially unchanged. Modifications of the traditional K file for the most part have centered around changes in the cross-sectional design, from square to triangular in smaller sizes, or to rhombus shape (1). These changes have resulted in improved instrument flexibility (2, 3) and cutting ability (4, 5) attributed to the decrease in instrument bulk along the shaft. The K-Flex file introduced in 1981 appears to be the first serious effort to improve the K file without mimicking H-type geometry or characteristics. For this reason it may be viewed as the forerunner of socalled "hybrid" instrument designs. The term hybrid as it pertains to endodontic instruments may be applied to those designs that attempt to integrate the strength and versatility of K-type files with the aggressive cutting properties of H-type instruments. The Unifile appears to be the first hybrid-type instrument per se since it displays features of both K-and H
Egyptian dental journal, 2021
Aim: The aim of the present study was to compare the cutting efficiency of XP-Endo shaper and iRaCe nickel titanium rotary instruments after different number of uses and to evaluate the surface characteristics. Methodology: Forty-eight mesial roots were divided into two groups (n= 24) according to the type of the file system used (XPS/iRaCe) and was then subdivided into three subgroups (n=8) according to the number of uses (first use, second use and third use). Each specimen was prepared and irrigation was done using 5 ml of freshly prepared 2.5% NOCL, then 3 ml of 17% EDTA followed by 10 ml of distilled water. All root samples were weighted before and after preparation and weight loss was calculated. Two samples (Size 30 and Taper 0.04) from each file system were randomly selected and photographed using Scanning Electron Microscope (SEM) before and after the third use, at magnification 150x and 2000x. Comparing the cutting efficiency of each group at the different number of uses wa...
A New Device to Test the Bending Resistance of Mechanical Endodontic Instruments
Applied Sciences
The aims of the present study were to propose a new machine for testing the bending behavior of an instrument at multiple specific points along the cutting surface and to compare the influence of proprietary heat treatment on the bending ability of EdgeTaper (ET), Protaper Universal (PTU), EdgeTaper Platinum (ETP), and Protaper Gold (PTG). A total of 320 instruments were examined in the present study: 80 ET, 80 PTU, 80 ETP, and 80 PTG. The bending ability of all instruments was tested at a 45° angle and on three different portions of the instrument at 3, 6, and 9 mm from the tip using a customized device. Statistical analysis showed significant differences among each single instrument of the series and between ET and PTU as well as ETP and PTG. The bending behavior of a nickel–titanium rotary instrument is its ability to bend without any plastic deformation. This feature, according to the results of the present study, is variable along the cutting surface; therefore, it should be ev...
Cutting efficiency of 3 different instrument designs used in reciprocation
Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2010
Objective. This study examined the effect of flute number and cross-sectional area on the cutting efficiency of 3 reciprocating endodontic instruments twisted from rectangular stainless steel wire; 40/0.02 instruments at 25-mm length were compared. Study design. Seventy-five anterior teeth were prepared, divided into 3 groups, and operated on with a reciprocating handpiece at 2500 rpm for 5 seconds at around 500 grams of force: Group 1, SafeSiders; Group 2, Dentsply K-Files; Group 3, Dentsply K-Reamers. Dentin generated was collected in weigh dishes. Cutting efficiency was determined by dentin weight. Statistical analysis was performed with 1-way ANOVA and the Student-Neuman-Keuls (SNK) multiple comparisons testing. Results. SafeSider instruments produced a greater amount of debris than K-Files and K-Reamers (P Ͻ .026). K-Files and K-Reamers were not statistically different (P ϭ .63). Conclusions. Flute number had no effect on cutting efficiency. Cross-sectional area may be a determining factor on cutting efficiency.
Engineering Failure Analysis, 2011
This study aims at evaluating the deformation changes on three types of root canal rotary instruments with different designs; the Pro-Taper Universal, the V-Taper, and the Liberator systems after clinical use. Measurements were made before and after the instruments were used for treating four human root canals by developing stereo-microscopic images for a number of instruments from the three systems at the same position. All images were transformed to AutoCAD to evaluate changes in measurements before and after use. The results showed that the majority of the tested instruments were subjected to significant deformations along the length of the working parts of the instruments. These deformations were only detected by the AutoCAD program but went unnoticed by either visual or microscopic examinations. The results suggest that AutoCAD could be a ground of developing a chair side ''computer image analysis program'' to predict and justify discarding of a piece before or during operation. In addition, considerations should be given to the material of construction and new approaches of ion implants, such as electro-polishing, that could improve or at least assist in enhancing the wear resistance of the instruments against the dentine surface.
Analysis of Torque and Force with Differently Tapered Rotary Endodontic Instruments In Vitro
Journal of Endodontics, 2005
The aim of this study was to compare torques and forces developed by two sequences of nickel-titanium rotary instruments, using only .04 taper instruments or a combination of .04 and .06 tapers, respectively. Curved canals in plastic blocks were shaped in a torque-testing device; torque, force, contact areas and numbers of working rotations were determined. Analysis of variance and Pearson correlation coefficients were used to compare the two sequences. Mean torque ranged from 0.2 Ϯ 0.03 to 3.19 Ϯ 0.28 Ncm and was higher for instrument sizes 25 to 45 in group A. Mean vertical forces ranged from 1.49 Ϯ 0.54 to 12.0 Ϯ 3.5 N; there were significant correlations between torque and force as well as between torque and contact areas. Numbers of rotations were lower in the combined .04 and .06 sequence. An instrumentation sequence encompassing various tapers seems to be safer regarding torsional and fatigue failure compared to a sequence that used one single taper. However, the former sequence requires the use of more instruments.
Sword of Endodontist: A Review
Dental Journal of Advance Studies, 2014
The last decade has been witness to phenomenal growth in endodontic technology. The introduction of these new technologies has resulted in endodontics becoming easier, faster and most importantly, better. NiTi alloys overall are softer than stainless steel, are not heat treatable, have a low modulus of elasticity (about one fourth to one fifth that of stainless steel) but a greater strength, are tougher and more resilient, and show shape memory and superelasticity. The latter two properties are the main reasons why NiTi alloys have succeeded in endodontics. The purpose of this article is to review the design features of different rotary instruments used for pulp space preparation. Important mechanical features include the variability of taper, rake angle, crosssectional geometry, tip configuration, design of blades, helical angle and pitch. These design features influence flexibility, cutting efficiency and safety. In this review, design features of commonly used NiTi rotary systems are summarized.
Comparative characteristics of endodontic drills
PubMed, 2015
The work concerns the analysis of influence of the wear process of endodontic instruments on the mechanical and physico-chemical properties of the materials from which they are made. A detailed study of the microstructure, mechanical properties and corrosion resistance in the environment simulating work of the tool was conducted. The research was done for the new Mtwo endodontic files and after six times of use. In addition, the observations with a scanning electron microscope in order to reveal possible damage caused by the impact of a corrosive environment were carried out. The results showed that use of the tool by six times revealed damage at the edges of the blades and may cause a lack of continuity of the cutting line resulting in the uneven distribution of the resistive force which acts on the tool during operation.