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PubMed2003

NH3/O2 mixed gas plasmas alter the interaction of blood components with stainless steel.

Stainless steel treated with a mixed gas plasma of NH(3) plus O(2) had chemical and biologic characteristics distinct from untreated stainless steel or stainless steel treated with NH(3) or O(2) plasmas used separately. NH(3)/O(2) plasmas deposited nitrogen as both -CN (organic) and -NO (nitrate, nitrite)--materials not found on untreated stainless steel--and the contact angle changed from 44 degrees to 23 degrees. Treatment of stainless steel (and titanium) resulted in surfaces with enhanced resistance to platelet and leukocyte attachment. A gas plasma of N(2)O/O(2) also was found to reduce platelet and leukocyte attachment, suggesting that these properties may be common to surfaces coated with oxynitrites (nitrides). Upon subcutaneous implantation, no inflammation, hemolysis, or untoward thrombosis was noted in the tissue surrounding the wafers treated with the NH(3)/O(2) plasmas, although the cellular density was considerably reduced by 2 weeks after implant. Collectively, the results suggest that NH(3)/O(2) plasmas impart a unique character to stainless steel that may be useful in the construction of medical devices.

Ammonia↗
PubMed2003

Corrosion resistance of stressed NiTi and stainless steel orthodontic wires in acid artificial saliva.

The purpose of this study was to investigate the corrosion resistance of stressed NiTi and stainless steel orthodontic wires using cyclic potentiodynamic and potentiostatic tests in acid artificial saliva at 37 degrees C. An atomic force microscope was used to measure the 3-D surface topography of as-received wires. Scanning electron microscope observations were carried out before and after the cyclic potentiodynamic tests. The surface chemical analysis was characterized using X-ray photoelectron spectroscopy and Auger electron spectroscopy after the potentiostatic tests. The cyclic potentiodynamic test results showed that the pH had a significant influence on the corrosion parameters of the stressed NiTi and stainless steel wires (p < 0.05). The pitting potential, protection potential, and passive range of stressed NiTi and stainless steel wires decreased on decreasing pH, whereas the passive current density increased on decreasing pH. The load had no significant influence on the above corrosion parameters (p > 0.05). For all pH and load conditions, stainless steel wire showed higher pitting potential and wider passive range than NiTi wire (p < 0.001), whereas NiTi wire had lower passive current density than stainless steel wire (p < 0.001). The corrosion resistance of the stressed NiTi and stainless steel wires was related to the surface characterizations, including surface defect and passive film.

Acids↗
PubMed2006

Adhesion enhancement of steel fibers to acrylic bone cement through a silane coupling agent.

The use of a silane coupling agent (methacryloxypropyl-trichlorosilane) to improve the mechanical properties of steel fiber-reinforced acrylic bone cements was assessed. Changes to the tensile and fracture properties of bone cements reinforced with silane-coated or uncoated 316L stainless steel fibers of different aspect ratios were studied. Contact-angle measurements indicated that the coupling agent coats the metal surface through room temperature treatments in a short time (within 2 h). Push-out tests indicated that the interfacial shear strength of silane-coated 316L stainless steel rods is 141% higher than the uncoated rods. The elastic moduli, ultimate stresses, and fracture toughness of the silane-coated, steel fiber-reinforced bone cements are significantly higher than the bone cements reinforced with uncoated steel fibers. There were no differences in the tensile mechanical properties of the silane-coated or uncoated, steel fiber-reinforced cements after aging in a physiological saline solution, indicating that the bonding effectiveness is decreased by the intrusion of water at the metal-polymer interface. Because of possible biocompatibility issues with leaching of the silane coupling agent and no long-term mechanical benefit in simulated aging experiments, the use of these agents is not recommended for in vivo use.

Adhesiveness↗
PubMed2006

Phosphorus removal by electric arc furnace steel slag and serpentinite.

Electric arc furnace (EAF) steel slag and serpentinite were tested in columns either alone or mixed with limestone to determine their capacity to remove phosphorus (P) from a solution containing initially 20mg P/L (for 114 days) than 400mg P/L (for 21 days). EAF steel slag was nearly 100% efficient due to specific P adsorption onto metal hydroxides and precipitation of hydroxyapatite. Serpentinite also showed a good performance that decreased with time, adsorption appearing to be the dominant mechanism for P removal. Mixing limestone with these two materials did not improve their performance and in the case of serpentinite, it actually even decreased it. In 114 days of experimentation, serpentinite alone and the mixture of serpentinite and limestone removed 1.0mg P/g while in 180 days of experimentation, EAF steel slag and the mixture of slag and limestone removed an average of 2.2mg P/g, without attaining their maximum P removal potential. The void hydraulic retention time (HRTv) was a key factor for growing hydroxyapatite crystals and had a significant effect on P removal efficiency by EAF steel slag. A temporary increase in HRTv caused by clogging resulted in an increase in EAF steel slag efficiency (from 80% to almost 100%) towards the end of investigation. Results from this study indicate that the use of EAF steel slag in constructed wetlands or filter beds is a promising solution for P removal via adsorption and precipitation mechanisms.

Minerals↗
PubMedDate not supplied

A comparison of winged steel needles and Teflon cannulas in maintaining intravenous access during gastrointestinal endoscopy.

We have conducted a prospective study in 142 consecutive patients undergoing either gastroscopy or colonoscopy. The patients were randomized to have either a 23-gauge winged steel needle or a 23-gauge Teflon cannula inserted. The two groups were well matched, with 71 patients receiving each device. Intravenous access was achieved in every case. The steel needle was inserted at the first attempt in 65 of 71 cases (91.6%) compared with 67 of 71 cases (94.4%) for the Teflon cannula. Extravasation occurred in only 1 of 71 cases (1.4%) with Teflon cannulas compared with 18 of 71 cases (25.5%) of steel needle use (p < 0.01). Additionally, no Teflon cannula blocked completely, whereas 1 of 71 steel needles (1.4%) did so. Only 1 of 71 (1.4%) of the Teflon cannulas became difficult to flush compared with 12 of 71 steel needles (16.9%). The Teflon cannula was as easy to insert and provided significantly more reliable intravenous access than the steel needle.

Adult↗
PubMed1995

Relative kinetic frictional forces between sintered stainless steel brackets and orthodontic wires.

The level of kinetic frictional forces generated during in vitro translation at the bracket-wire interface were measured for two sintered stainless steel brackets as a function of two slot sizes, four wire alloys, and five to eight wire sizes. The two types of sintered stainless steel brackets were tested in both 0.018-inch and 0.022-inch slots. Wires of four different alloy types, stainless steel (SS), cobalt chromium (Co-Cr), nickel-titanium (Ni-Ti), and beta-titanium (beta-Ti), were tested. There were five wire sizes for the 0.018-inch slot and eight wire sizes for the 0.022-inch slot. The wires were ligated into the brackets with elastomeric ligatures. Bracket movement along the wire was implemented by means of a mechanical testing instrument, and time dependent frictional forces were measured by a load cell and plotted on an X-Y recorder. For most wire sizes, lower frictional forces were generated with the SS of Co-Cr wires than with the beta-Ti or Ni-Ti wires. Increase in wire size generally resulted in increased bracket-wire friction. There were no significant differences between manufacturer for the sintered stainless steel brackets. The levels of frictional force in 0.018-inch brackets ranged from a low of 46 gm with 0.016-inch Co-Cr wire to a high of 157 gm with 0.016 x 0.025-inch beta-Ti wire. In comparing the data from a previous study by Kapila et al. 1990 performed at OUHSC with the same apparatus, the friction of sintered stainless steel brackets was approximately 40% to 45% less than the friction of the conventional stainless steel brackets.

Analysis of Variance↗
PubMed2003

Release of nickel ions from stainless steel alloys used in dental braces and their patch test reactivity in nickel-sensitive individuals.

Nickel ions leached in sufficient quantities from nickel-containing alloys may induce nickel sensitization or elicit allergic contact dermatitis. Nickel-containing stainless steel alloys are generally considered safe for nickel-sensitive individuals to use. The study summarized in this paper investigated 3 parameters. First, the release of nickel was estimated in artificial saliva and sweat from 4 different stainless steel alloys frequently used in dental braces. Second, in a pilot study, oral mucosa cells harvested from 3 dental patients before and after the attachment of dental braces were analysed for possible nickel content. Third, patch test reactivity of the 4 stainless steel alloys was tested on 31 nickel-sensitive subjects. All 4 stainless steel alloys released small amounts of nickel ions into artificial saliva (<0.13 micro g/cm2/week) and artificial sweat (<0.05 micro g/cm2/week), but no measurable amounts of nickel were found in any of the oral mucosa samples. None of the 31 nickel-sensitive subjects reacted to patch testing with the 4 stainless steel alloys, indicating that these stainless steel alloys would be safe to use in direct and prolonged contact with the skin.

Dental Alloys↗
PubMed2005

General dental practitioners' views on the use of stainless steel crowns to restore primary molars.

AIM: To ascertain general dental practitioners' views on the use of stainless steel (pre-formed metal) crowns to restore carious primary molars. METHOD: Ninety-three general dental practitioners were selected at random from those practising in Lancashire, Cheshire and Greater Manchester in 2003 and interviewed separately about the clinical care they provide to the primary dentition. Before the interview participants recorded the care they would provide for a case scenario, describing a child with a carious lesion that the British Society of Paediatric Dentistry (BSPD) guidelines indicate should be treated with a stainless steel crown. RESULTS: In answering the case scenario only six (7%) of the dentists reported that they would fit a stainless steel crown. Of the 93 dentists interviewed 71% knew of the BSPD guidelines, but only 18% had ever fitted a stainless steel crown in general practice. Reasons given for not using stainless steel crowns were they are inappropriate for many children, time consuming to fit, difficult to manipulate, expensive, and ugly. CONCLUSION: The BSPD guidelines on the use of stainless steel crowns do not reflect the views of the majority of general dental practitioners who consider these crowns unsuitable for most children and an impractical restorative technique in busy daily practice.

Attitude of Health Personnel↗
PubMed1999

Heat transfer analysis of staphylococcus aureus on stainless steel with microwave radiation.

Staphylococcus aureus (NCTC 6571; Oxford strain) on stainless steel discs was exposed to microwave radiation at 2450 MHz and up to 800 W. Cell viability was reduced as the exposure time increased, with complete bacterial inactivation at 110 s, attaining a temperature of 61.4 degrees C. The low rate of temperature rise, RT, of the bacterial suspension as compared with sterile distilled water or nutrient broth suggests a significant influence of the microwave sterilization efficacy on the thermal properties of the micro-organisms. The heat transfer kinetics of thermal microwave irradiation suggest that the micro-organism has a power density at least 51-fold more than its surrounding liquid suspension. When the inoculum on the stainless steel disc was subjected to microwave radiation, heat conduction from the stainless steel to the inoculum was the cause of bacteriostasis with power absorbed at 23.8 W for stainless steel and 0.16 W for the bacteria-liquid medium. This report shows that the microwave killing pattern of Staph. aureus on stainless steel was mainly due to heat transfer from the stainless steel substrate and very little direct energy was absorbed from the microwaves.

Hot Temperature↗
PubMedDate not supplied

A simple technique for arthroscopic suture fixation of displaced fracture of the intercondylar eminence of the tibia using folded surgical steels.

SUMMARY: The purpose of this article is to describe a new and simple technique for arthroscopic suture fixation of avulsion fractures of the intercondylar eminence of the tibia using surgical steels as both suture passers and suture. The looped ends of 2 folded surgical steels being used as suture passers were inserted through 2 tibial drill holes and through the reduced bone fragment into the knee joint cavity and pulled out through the anteromedial portal in front of the knee joint. Outside the knee joint, a third unbent surgical steel to be used as a suture was tied to the 2 small loops of the folded surgical steels very easily. The ends of the folded surgical steels outside the tibia were then retracted back through the tibial drill holes, thereby automatically bringing the third surgical steel through the holes while making a loop over the avulsed fragment. The advantage of this technique is that the suture can be tied to the suture passers outside of the knee joint.

Adult↗
PubMed1997

Effect of stainless steel and titanium low-contact dynamic compression plate application on the vascularity and mechanical properties of cortical bone after fracture.

OBJECTIVES: Comparison of the effect of stainless steel and titanium low-contact dynamic compression plate application on the vascularity and mechanical properties of cortical bone after fracture. DESIGN: Randomized, prospective. SETTING: Orthopaedic research laboratory. ANIMALS: Ten large (greater than twenty-five kilogram) adult dogs. INTERVENTION: A short, midshaft spiral tibial fracture was created, followed by lag screw fixation and neutralization with an eight-hole, 3.5-millimeter, low-contact dynamic compression plate (LCDCP) made of either 316L stainless steel (n = five) or commercially pure titanium (n = five). After surgery, animals were kept with unrestricted weight-bearing in individual stalls for ten weeks. MAIN OUTCOME MEASUREMENTS: Cortical bone blood flow was assessed by laser Doppler flowmetry using a standard metalshafted probe (Periflux Pf303, Perimed, Jarfalla, Sweden) applied through holes in the custom-made LCDCPs at five sites. Bone blood flow was determined at four times: (a) prefracture, (b) postfracture, (c) postplating, and (d) ten weeks postplating. After the dogs were killed, the implant was removed and both the treated tibia and contralateral tibia were tested for bending stiffness and load to failure. RESULTS: Fracture creation decreased cortical perfusion in both groups at the fracture site (p = 0.02). The application of neither stainless steel nor titanium LCDCPs further decreased cortical bone blood flow after fracture creation. However, at ten weeks postplating, cortical perfusion significantly increased compared with acute postplating levels in the stainless steel (p = 0.003) and titanium (p = 0.001) groups. Cortical bone blood flow ten weeks postplating was not significantly different between the titanium group and the stainless steel group. Biomechanical tests performed on the tibiae with the plates removed did not reveal any differences in bending stiffness nor load required to cause failure between the two groups. CONCLUSIONS: Both titanium and stainless steel LCDCPs were equally effective in allowing revascularization, and neither provided a significant advantage in biomechanical properties of fracture healing at ten weeks.

Analysis of Variance↗
PubMed2003

Effects of steel scalpel, ultrasonic scalpel, CO2 laser, and monopolar and bipolar electrosurgery on wound healing in guinea pig oral mucosa.

OBJECTIVE: The study's objective was to compare instrument performance and tissue healing when steel scalpel, ultrasonic scalpel, monopolar or bipolar electrosurgical instruments, or CO2 laser was used in an animal oral surgery model. STUDY DESIGN: Prospective, blinded, randomized. METHODS: Adult guinea pigs (N = 70) were randomly assigned to 5 groups (14 animals per group) for excision of 2-cm, full-thickness oral mucosa using steel scalpel, ultrasonic scalpel, monopolar or bipolar electrosurgical instruments, or CO2 laser. Postoperative pain was measured indirectly using weekly body weight changes. Animals from each group were killed on days 0, 7, 14, 21, and 28. Specimens were harvested for blinded histopathological study and tensile strength measurement. Instrument performance (hemostasis, tissue coagulation, tissue sticking) and wound healing (tissue re-epithelialization, degree of inflammation) were primary outcomes. Statistical analysis was performed using analysis of variance. RESULTS: The ultrasonic scalpel was the best tool in controlling hemostasis, tissue coagulation, and tissue sticking. Significantly higher body weight gain ( P<.05) was noted at day 7 for monopolar and CO2 laser groups. Greatest tensile strength was seen in the steel scalpel and ultrasonic scalpel groups at the end of 28 days. Tissue re-epithelialization was fastest for the steel scalpel and ultrasonic scalpel groups (complete by day 7). Complete re-epithelialization of wounds of all treatment groups occurred by day 28. All groups had acute inflammation. Complete resolution of inflammation by day 14 took place in the steel scalpel and ultrasonic scalpel groups only. CONCLUSION: Use of the ultrasonic scalpel produced faster re-epithelialization and greater tensile strength than laser or electrosurgical instruments, with results comparable to those seen with the steel scalpel.

Animals↗
PubMed2005

Comparison of titanium and Robinson stainless steel stapes piston prostheses.

OBJECTIVE: Although stainless steel stapes prostheses have generally been considered magnetic resonance imaging safe, there is concern that this may change with the development of more powerful imaging systems. The objective of the study was to determine whether a titanium piston stapes prosthesis would be audiometrically and surgically equivalent to a Robinson stainless steel piston for stapedectomy. STUDY DESIGN: Retrospective chart review. SETTING: Private otology practice. PATIENTS: In all, 50 patients underwent stapedectomy with a Gyrus titanium piston prosthesis. These patients were matched on the basis of age and preoperative bone-conduction scores with patients who underwent stapedectomy with a Robinson stainless steel piston prosthesis. MAIN OUTCOME MEASURES: Audiometric results are analyzed, and surgical complications noted. RESULTS: There was no significant difference between groups in hearing improvement or postoperative air-bone gap. The mean four-frequency hearing improvement was 27.7 dB for the stainless steel group and 27.8 dB for the titanium group. The mean postoperative air-bone gap was 2.65 dB for the stainless steel group and 2.60 for the titanium group. Neither group had a surgical complication. CONCLUSION: The titanium stapes prosthesis is a good alternative to a stainless steel prosthesis.

Adult↗
PubMed2004

Embolotherapy of pulmonary arteriovenous malformations: efficacy of platinum versus stainless steel coils.

PURPOSE: To compare the results of embolotherapy of pulmonary arteriovenous malformations (PAVMs) with use of platinum versus stainless-steel coils. MATERIALS AND METHODS: From a database of 78 consecutive patients with PAVMs treated by embolotherapy between May 1992 and September 2001, 54 patients with 306 PAVMs were selected for retrospective evaluation. Exclusion criteria were PAVMs with less than 12 months of follow-up computed tomography (CT) of the thorax (n = 15), embolotherapy with a mixture of embolic materials (n = 8), and repeat embolotherapy for previous treatment failures (n = 1). Successful treatment was defined as complete resolution of the aneurysm sac and draining vein on follow-up CT (all patients) and/or absence of contrast material flow through the PAVM on pulmonary angiography (n = 27). RESULTS: Of 267 PAVMs embolized with stainless-steel coils, 249 (93.3%) were successfully occluded (mean follow-up, 3.1 years). Of 39 PAVMs embolized with platinum coils, 35 (89.7%) were successfully occluded (mean follow-up, 2.1 years). There was no significant difference in success between the two groups (P =.5). The mean feeding artery size was significantly larger (P <.0001) in the platinum group (4.3 mm) than in the stainless-steel group (3.5 mm). Potentially serious complications included coil reflux (n = 3), PAVM perforation (n = 2), self-limited neurologic deficit (n = 2), and systemic embolization of a coil (n = 1) in the stainless-steel group, and PAVM perforation (n = 2) in the platinum group. There were no long-term sequelae. CONCLUSIONS: Coil embolotherapy is highly efficacious, with no statistically significant difference between platinum and stainless-steel coils. The slightly higher proportion of sustained occlusion with stainless-steel coils may be partly explained by the larger mean feeding artery size in the platinum group. The study is limited by the small sample size of the platinum group.

Adult↗
PubMed2006

Electrochemical properties of 316L stainless steel with culturing L929 fibroblasts.

Potentiodynamic polarization and impedance tests were carried out on 316L stainless steel with culturing murine fibroblast L929 cells to elucidate the corrosion behaviour of 316L steel with L929 cells and to understand the electrochemical interface between 316L steel and cells, respectively. Potential step test was carried out on 316L steel with type I collagen coating and culturing L929 cells to compare the effects of collagen and L929 cells. The open-circuit potential of 316L steel slightly shifted in a negative manner and passive current density increased with cells, indicating a decrease in the protective ability of passive oxide film. The pitting potential decreased with cells, indicating a decrease in the pitting corrosion resistance. In addition, a decrease in diffusivity at the interface was indicated from the decrease in the cathodic current density and the increase in the diffusion resistance parameter in the impedance test. The anodic peak current in the potential step test decreased with cells and collagen. Consequently, the corrosion resistance of 316L steel decreases with L929 cells. In addition, collagen coating would provide an environment for anodic reaction similar to that with culturing cells.

Animals↗
PubMed2004

Investigation of the microstructure and mesotexture formed during thermomechanical controlled rolling in microalloyed steels.

Thermomechanical controlled rolling (TMCR) has been widely used as an effective method to improve the properties of steels. In the present paper, two commercial TMCR microalloyed steels were investigated. The grain size distributions and grain boundary misorientation angles were measured using electron backscattered diffraction patterns obtained using orientation imaging microscopy (OIM). The equivalent grain diameters were also measured using optical microscopy. Mixed coarse- and fine-grained regions were observed and the microhardness values were measured for both areas. Grain boundary misorientation angle distributions showed that the magnitude of mesotexture developed in the steel is dependent upon the rolling passes, the reduction ratio and the rolling temperatures including the finish rolling temperature. The surface layer, up to 2 mm depth, in Com-A steel had about 55% of grain boundaries with a misorientation angle below 12 degrees, much higher than in the central area ( approximately 30%), whereas Com-B steel showed similar distributions from the rolling surface to the centre. Misorientation results obtained from laboratory rolled steel plates with various TMCR procedures are also discussed as are OIM results from Charpy impact brittle fracture surfaces examining the effect of misorientation on crack propagation.

Alloys↗
PubMed1996

Torsional and bending properties of stainless steel and nickel titanium Canal Master U and Flexogate instruments.

The purpose of this study was to assess and to compare the torsional and bending properties of the Canal Master U (CMU) and Flexogate instruments made of stainless steel and nickel titanium. The bending moment, the torsional moment and angular deflection were measured according to ANSI/ADA specification number 28 and ISO reference number 3630. Ten instruments of each size, sizes 25 to 40 were used for each test. Nickel titanium instruments were significantly more flexible than stainless steel files. With regard to the torsional moment, values obtained were below the standards in all sizes except stainless steel CMU sizes 25, 35 and 40, and nickel titanium CMU size 25. Nickel titanium instrument also showed the highest angular deflection values. There were statistically significant differences between nickel titanium files and stainless steel Flexogates and between stainless steel Flexogates and stainless steel CMU. Based on these findings, the use of nickel titanium CMU and Flexogates is encouraged. Given the perceived advantages of both CMU and Flexogate instruments over conventional files for canal preparation, it would appear desirable to have the torque resistance of these instruments improved.

Dental Instruments↗
PubMed2000

Increased risk of restenosis after placement of gold-coated stents: results of a randomized trial comparing gold-coated with uncoated steel stents in patients with coronary artery disease.

BACKGROUND: Gold is a highly biocompatible material. Experimental evidence suggests that coating the stent with a gold layer may have a beneficial influence. In this randomized trial, we assessed whether gold-coated stents were associated with a better clinical and angiographic outcome after coronary placement. METHODS AND RESULTS: Patients with symptomatic coronary artery disease were randomly assigned to receive either a gold-coated Inflow stent (n = 367) or an uncoated Inflow stainless steel stent (n = 364) of identical design. Follow-up angiography was routinely performed at 6 months. The primary end point of the study was the occurrence of any adverse clinical event (death, myocardial infarction, or target-vessel revascularization) during the first year after stenting. At 30 days, there was no significant difference in the combined incidence of adverse events, with 7.9% in the gold-stent group versus 5.8% in the steel-stent group (P = 0.25). The incidence of angiographic restenosis (> or =50% diameter stenosis) was 49.7% in the gold-stent group and 38.1% in the steel-stent group (P = 0.003). One-year survival free of myocardial infarction was 88.6% in the gold-stent group and 91.8% in the steel-stent group (P = 0.14). One-year event-free survival was significantly less favorable in the gold-stent group (62.9% versus 73.9% in the steel-stent group; P = 0.001). CONCLUSIONS: Coating steel stents with gold had no significant influence on the thrombotic events observed during the first 30 days after the intervention. However, gold-coated stents were associated with a considerable increase in the risk of restenosis over the first year after stenting.

Aged↗