Steel Files Research Articles

爪甲下黒色腫 外傷後に生じた悪性黒色腫の１例

This report deals with a case of malignant melanoma following injury in a 30-year-old female. She dropped a steel file on her rt. great toe to develop subungual hematoma at the age of 25. After nail avulsion, a granulomatous tumor was observed on the nail bed. Histpathologically, the tumor consisted of round or spindle shaped cells and had a little pigments. Immunohistochemically, the tumor was partially positive for S-100 protein and HMB-45, and was diagnosed acral lentiginous melanoma (ALM) . Amputation of rt. great toe followed by groin dissection were performed. Postoperative diagnosis was ALM Stage III (pT4 N0 M0).

A comparison of canal preparation with nickel-titanium and stainless steel instruments

Maintaining the original canal path during instrumentation is a challenge in narrow curved canals. This study compared the maintenance of the original canal path of curved root canals during instrumentation with nickel-titanium (Mac) hand files, nickel-titanium engine-driven files, and stainless steel (K-Flex) files. Canal path maintenance was determined by superimposing instrumentation radiographs over an initial file radiograph and examining for discrepancies. Nickel-titanium hand and engine-driven instruments maintained the original canal path in all cases. The incidence of deviation from the original canal path during instrumentation with stainless steel files increased with file size. The difference between nickel-titanium groups and stainless steel became statistically significant with instruments larger than size 30. In this study, nickel-titanium files were more effective in maintaining the original canal path of curved root canals when the apical preparation was enlarged beyond size 30.

RS 5 Stainless steel and NiTi files: Their wear with usage

RS 5 Stainless steel and NiTi files: Their wear with usage

RS 4 Torsional properties of stainless steel and nickle-titanium endodontic files

RS 4 Torsional properties of stainless steel and nickle-titanium endodontic files

An evaluation of nitinol and stainless steel files used by dental students during a laboratory proficiency exam

Eighty-one dental students instrumented two curved canals in acrylic blocks with the use of stainless steel files in one block and nitinol files in the other. Overlay tracings were made of photographs taken before and after instrumentation of the acrylic blocks and differences between the tracings were measured along the canal walls. The canals instrumented with nitinol files were shaped better than those instrumented with stainless steel files; working length was maintained more often without ledging the canal walls and with less zipping of the apical foramen.

PC 16 The effect of corrosion on two stainless steel files

PC 16 The effect of corrosion on two stainless steel files

Abstract #33 — Flexibility/torsional properties of nickel titanium and stainless steel files

Abstract #33 — Flexibility/torsional properties of nickel titanium and stainless steel files

Wear behaviour in the presence of magnetic fields for pin-on-disc repeated dry wear tests

Wear behaviour in a magnetic field is discussed for pin-on-disc repeated dry wear tests. The results showed that the sliding distance corresponding to a severe-mild wear transition decreased with increasing magnetic flux density. Consequently, the degree of wear also decreased in the presence of a magnetic field. These phenomena were observed, remarkably, for the case using a carbon steel pin, which is a material that easily oxidizes. To discuss the above phenomena, the oxidation of steel filings in a magnetic field was investigated at high temperature. As a result, it was certain that the activation energy for oxidation decreased both in ac and dc magnetic fields. EPMA observations also proved that the magnetic field promoted oxidation. It was concluded that the degree of wear decrease was caused by magnetic-field-promoted oxidation of wear particles and these oxidized fine wear particles existed and attached to the wear surface owing to the magnetic forces present.

An initial investigation of the bending and torsional properties of nitinol root canal files

Root canal files in size #15 and triagular cross-sections were fabricated from 0.020-inch diameter arch wires of Nitinol, a nickel-titanium orthodontic alloy with a very low modulus of elasticity. A unique manufacturing process was used in which the fluted structure of a K-type file was machined directly on the starting wire blanks. The Nitinol files were found to have two to three times more elastic flexibility in bending and torsion, as well as superior resistance to torsional fracture, compared with size #15 stainless steel files manufactured by the same process. The fracture surfaces for clockwise and counterclockwise torsion were observed with the scanning electron microscope and exhibited a largely flat morphology for files of both alloy types and torsional testing modes. It was possible to permanently precurve the Nitinol files in the manner often used by clinicians with stainless steel files. These results suggest that the Nitinol files may be promising for the instrumentation of curved canals, and evaluations of mechanical properties and in vitro cutting efficiency are in progress for size #35 instruments. Root canal files in size #15 and triagular cross-sections were fabricated from 0.020-inch diameter arch wires of Nitinol, a nickel-titanium orthodontic alloy with a very low modulus of elasticity. A unique manufacturing process was used in which the fluted structure of a K-type file was machined directly on the starting wire blanks. The Nitinol files were found to have two to three times more elastic flexibility in bending and torsion, as well as superior resistance to torsional fracture, compared with size #15 stainless steel files manufactured by the same process. The fracture surfaces for clockwise and counterclockwise torsion were observed with the scanning electron microscope and exhibited a largely flat morphology for files of both alloy types and torsional testing modes. It was possible to permanently precurve the Nitinol files in the manner often used by clinicians with stainless steel files. These results suggest that the Nitinol files may be promising for the instrumentation of curved canals, and evaluations of mechanical properties and in vitro cutting efficiency are in progress for size #35 instruments.

Separating instrument technique for root canal filling: a case report

Summary. When no accepted method of canal sealing is possible in narrow curved cancals, intentionally separating stainless steel files in the canal can be considered. A case is presented in which this method was applied in aseverely curved mesial root of a lower second molare with a 4‐year follow‐up. The advantages and disadvantages of this method are discussed.

Effect of sterilization and irrigants on the cutting ability of stainless steel files

The effect of sterilization and irrigants on the cutting ability of stainless steel files was determined. Dry heat or salt sterilization had no effect, but autoclave sterilization caused a reduction in their cutting ability. Sodium hypochlorite, hydrogen peroxide, and EDTA-urea peroxide (UP) irrigants caused a decrease in the cutting ability of the files, but the saline irrigant had no effect.

An in vitro study of the comparative effectiveness of obturating curved root canals with gutta-percha cones, silver cones, and stainless steel files

The quality of apical seal obtained with gutta-percha cones, silver cones, and stainless steel files was assessed in 120 freshly extracted teeth with moderately or severely curved root canals. Teeth were coated with wax, except in the apical foramen area, and immersed in 2 percent methylene blue solution for 48 hours. Apical leakage was quantitated by a linear measurement of the distance that the dye penetrated along the root canal and by a volumetric measurement of the quantity of dye within the root. There was a highly significant (p < 0.001) correlation between the two measurements. Root canals filled with silver cones showed significantly less apical leakage than those filled with gutta-percha or stainless steel files, regardless of degree of curvature. For both silver cones and stainless steel files, leakage was less in severely curved roots than in moderately curved roots.

Cutting ability of K type endodontic files

The cutting ability of K type stainless steel files was measured on an instrument that controlled the force on the files and the length and number of strokes. The depth of cuts in poly(methyl methacrylate) was used to determine cutting ability. The cutting ability of a single surface of a file did not decrease as a result of 6,100 strokes. The cutting ability of individual files varied considerably, but good reproducibility was found for the same file with various numbers of strokes. The wear of files did not have a significant effect on the cutting ability of the files.

A new gutta-percha technique

A sealer, stainless steel files, and thermally plasticized gutta-percha were used in a filling technique to obtain a three-dimensional obturation of the root canal system. The technique eliminates the fitting of a master cone and does not require the special skills that are needed in other techniques for the apical placement of master cones.

X-ray line-broadening studies on austenitic stainless steel filings

A study of stacking-fault parameters, microstrains and domain size has been made using X-ray line profile analysis on manually prepared austenitic stainless steel (18% Cr, 9% Ni and 0.07% C) filings. Studies were carried out at room temperature and on filings annealed at 180, 350 and 500°C. Results obtained through studies based on integral breadths, variance analysis and Fourier methods are compared.

Sealing quality of instruments cemented in root canals with polycarboxylate cements

Stainless steel files were cemented in place as the master cone with Durelon, PCA, and Proco-sol. The treated teeth were immersed in, dye; after 2, 4, 8, and 16 days, they were examined for evidence of dye penetration. The depth of dye penetration for each group was compared with the use of the t test. The results showed that none of the test groups belonged to the same general distribution. Although PCA sealed better than Durelon, both were considered unsatisfactory when compared to Proco-sol. Stainless steel files were cemented in place as the master cone with Durelon, PCA, and Proco-sol. The treated teeth were immersed in, dye; after 2, 4, 8, and 16 days, they were examined for evidence of dye penetration. The depth of dye penetration for each group was compared with the use of the t test. The results showed that none of the test groups belonged to the same general distribution. Although PCA sealed better than Durelon, both were considered unsatisfactory when compared to Proco-sol.

Rack-and-pinion motors: hybrid of linear and rotary machines

The field over an open-sided linear motor contains a rotating component which can be used to spin rotors of a variety of types. If the field of the linear motor is visualised as a magnetic ‘river’, the motion is analogous to a mechanical rack and pinion. The paper concentrates on reluctance- and hysteresis-type rotors which can develop substantial torque in small sizes. It is shown that the possible acceleration of steel rotors increases with decrease in size. The effect of linear-motor fields on iron and steel filings is investigated and a demonstration of rack-and-pinion action using a permanent magnet is described.

A comparison of root canal preparations using stainless steel, Ni-Ti hand, and Ni-Ti engine-driven endodontic instruments – an in vitro study

The main advantage of nickel titanium instruments is that they permit canal preparation with less transportation and ledging. Hand used Ni-Ti and rotary Ni-Ti instruments have a wider range of elastic deformation and greater flexibility. The aim of the present study was to evaluate and compare the preparation time, loss of working length, apical transportation, instrument deformation and fracture with stainless steel, Ni-Ti hand and Ni-Ti rotary endodontic instruments. Fifty freshly extracted human mandibular molars with curved roots were collected and stored in 10% formalin. The samples were divided into 3 groups of 15 each. The access opening was made for each tooth and the biomechanical preparation was carried out using crown down pressureless technique in all the groups. Group I was instrumented with stainless steel files, group II with hand Ni-Ti and group III with Ni-Ti rotary files. The preparation time to enlarge each canal was recorded in minutes and seconds, which included only active instrumentation. Following preparation, the final length of each canal was subtracted from the original length to give the loss of working length. SEM photographs of the deformed and fractured instruments were taken. The apical transportation was measured using computer software (Microdraw 4.1). The readings were noted and statistically analyzed.The results of this in vitro study showed that the mean preparation time was less with Ni- Ti rotary (1.85 min) when compared to hand Ni-Ti (6.33) and stainless steel files (6.73), which was statistically significant. The loss of working length was more for stainless steel group which was statistically significant (P&lt;0.05) when compared with the other 2 groups.One instrument in stainless steel and one in Ni-Ti rotary files were fractured. Only one instrument in stainless steel file deformed permanently. Apical transportation was found to be greater in stainless steel group than other groups (P&lt;0.01) which was statistically significant. Considering the parameters in this study, Ni-Ti rotary files proved to perform better than the other two groups. Key words: Canal preparation; crown-down pressure less technique; double exposure radiographic technique. DOI: 10.3329/bjms.v9i4.6689Bangladesh Journal of Medical Science Vol.09 No.4 July 2010 pp.223-230

The effect of the degree of work hardening on the friction and wear of metals during abrasion

The friction, wear and surface microhardness of the face-centred cubic pure metals Al, Cu, Ag and Au, during abrasion on dry steel files at 1 kg load, were investigated as a function of the degree of work hardening. It was found that the friction-microhardness, and to a less certain extent the wear-microhardness loci of these metals progressively work hardened from the annealed state, corresponded closely to those found for different fully abraded cubic metals of a similar range of hardness.

Friction, wear and surface hardness in abrasion of binary solid-solution alloys in the copper-gold system

The friction coefficient μ, the mass wear rate M and the surface micro-hardness HD are measured in abrasion of Cu-Au alloys (in the fully abraded, and thus fully work-hardened, surface state), sliding on dry `smooth-cut' steel files at a load of about 1 kg and a speed of a few cm s−1.μ and M/ρ (where ρ is the density) are found to be nearly the same as for a pure cubic metal of similar HD, and vary with alloy composition in a nearly parabolic manner analogous to that found by Sachs and Weerts for the shear stress of Ag-Au alloys. The deviations Δμ and Δ(M/ρ) from a Vegard's-law type of linear dependence on composition are approximately proportional to each other and to|Δa|, the lattice dimension deviation from Vegard's law, but they vary non-linearly with ΔHD. Similar results are indicated for the Cu-Zn and Cu-Ni alloy systems. On this basis the probable μ, M/ρ and HD can be estimated for abrasion of face-centred-cubic alloys of other binary solid-solution systems. The stored energy in the abraded alloy surface regions is also estimated from μ and M.