Multistranded Stainless Steel Wires Research Articles

Efficacy of Esthetic Retainers: Clinical Comparison between Multistranded Wires and Direct-Bond Glass Fiber-Reinforced Composite Splints

The purpose of this longitudinal prospective randomized study was to evaluate the reliability of two different types of orthodontic retainers in clinical use: a multistrand stainless steel wire and a polyethylene ribbon-reinforced resin composite. Moreover the level of satisfaction of the patient about the esthetic result was also analyzed by means of a Visual Analogue Scale (VAS). 34 patients (9 boys and 25 girls, mean age 14.3), in the finishing phase of orthodontic treatment, were selected for the study. Since splints were applied the number, cause, and date of splint failures were recorded for each single tooth over 12 months. Statistical analysis was performed using a paired t-test, Kaplan Meier survival estimates, and the log-rank test. Kruskal Wallis test was performed to analyze VAS recordings. Differences between the bond failure rates were not statistically significant. Esthetic result of VAS was significantly higher for polyethylene ribbon-reinforced resin retainers than for stainless steel wires.

Application of fiber-reinforced composite as fixed lingual retainer

To investigate mechanic properties of fiber-reinforced composite (FRC) and its influence on maintaining periodontal health. Sixty patients completing orthodontic treatment were randomized into two groups with FRC and multistrand stainless steel wire (MSSW) being applied as fixed lingual retainer. Bleeding index (BI) and pocket depth(PD) were recorded right after, 6 months and 12 months after bonding the retainer. Flexural modulus and maximum shear bond strength were tested for FRC and MSSW. Statistical significance was found at the increase of BI from right after bonding, 6 months after to 12 months after for both groups (P < 0.05), while no statistically significant change was found in PD among the three time points (P > 0.05). There were no difference between the two groups at each time point regarding BI and PD (P > 0.05). The flexural modulus and maximum shear bond strength of FRC were both below to that of MSSW under the same test situation (P < 0.001). It is necessary to improve the bonding strength of FRC and reduce its negative effect on periodontal health in addition to its advantage of convenience.

A new non-operative approach to fistula in ano.

The results of a new out-patient approach to fistula in ano are presented. The technique involved passing a multi-strand stainless steel wire through the fistulous tract and has been used in 56 patients with low fistulae as well as high horseshoe anal fistulae. Recurrence was seen in only 2 patients and none of the patients experienced temporary or permanent incontinence of flatus or faeces.

A comprehensive survey of retention procedures in Australia and New Zealand

Abstract Objectives: This survey aimed to identify consistencies in retention procedures. Methods: Three hundred Australian orthodontists and 70 New Zealand orthodontists were randomly selected for the study. A questionnaire gathered their views regarding the most commonly used retainers, wire types and sizes of bonded retainers, factors influencing the design of retainers, duration of regular retention, definition of permanent retention, percentage of cases that needed permanent retention, factors influencing the decision to use permanent retention, changes in retention protocols over the last five years, and reasons for such changes. Results: Upper invisible and lower canine-to-canine bonded retainers were the most commonly used retainers. Pretreatment tooth position was the major factor influencing the design of retainers, and most respondents preferred bonded retainers. The majority preferred multistrand stainless steel wire for bonded retainers. The most common wire size was 0.0175 inch. Orthodontists more commonly recommended a regular retention period of more than two years, and defined permanent retention as “lifetime”. Orthodontists applied permanent retention to either a very high or very low percentage of their cases. A high percentage of respondents made changes to their retention protocols over the past five years. There was no relationship between factors influencing the design of retainers and the preferred type of retainer. There was no consensus on the major factor influencing the decision to use permanent retention. Conclusions: Retention procedures are variable and dependent largely on personal preferences. There does not seem to be any consistent pattern in the application of retention methodologies.

Deactivation force-deflection behavior of multistranded stainless steel wires

This investigation measured the deactivation (unloading) force-deflection behavior of selected multistranded stainless steel orthodontic wires. The guidelines from the revised American National Standards Institute/American Dental Association Specification No. 32 for orthodontic wires (type 2, nonlinear elasticity) were used to perform a 3-point bending test to obtain data for the deactivation force levels at 3, 2, 1, and 0.5 mm, and permanent deformation values. The study tested 20 wire designs: triple-stranded twisted wires, 5- and 6-stranded coaxial wires, and 8- and 9-stranded braided rectangular wires of selected cross-sections. Twenty specimens were tested for each wire design. The specification guidelines for testing provided a means for obtaining comparative unloading force delivery data for the deflections tested. Multistranded wires of significantly different cross-section, weave, and strand number fell within relatively narrow ranges of force delivery at the 0.5-mm (1.7-42.7 grams-force [gmf]) and 1-mm (31.1-134.2 gmf) deflections and wider ranges of force levels at the 2-mm (57.0-320.5 gmf) and 3-mm (72.5-451.8 gmf) deflections. All wires exhibited some permanent deformation, but none averaged greater than 0.66 mm. The testing also showed that multistranded wires of significantly different design exhibit similar force levels. The guidelines of the revised Specification No. 32 yielded deactivation data with regard to force delivery and provided comparisons of the wire designs tested.

Resistance to sliding of stainless steel multistranded archwires and comparison with single-stranded leveling wires

The sliding mechanics of multistranded stainless steel (SS) wires were compared with single-stranded leveling wires in the passive and the active regions when dominated by classical friction and elastic binding, respectively. Tests were done under both dry and wet (human saliva) conditions. The round multistranded wires had 3- (triple) and 6-stranded (coax) configurations in nominal sizes of 15.5, 17.5, 19.5, and 21.5 mil; the rectangular wires had 3- (rect3) and 8-stranded (rect8) configurations in nominal sizes of 16 × 16, 16 × 22, 17 × 25, and 19 × 25 mil. While a ligature force of 150 g was applied and the second-order angulation was varied from −12° to 12°, each wire was translated relative to its bracket as the drawing force was digitally recorded. Linear regressions were fitted separately to the passive and the active regions. In the passive region, the kinetic coefficients of friction μk-FR in the wet state were the same as, lower than, and higher than in the dry state for single-stranded SS, single-stranded nickel titanium (NiTi), and multistranded SS wires, respectively. Because the kinetic coefficients of friction were similar for multistranded and single-stranded SS wires, μk-FR is a material property for SS and perhaps also for NiTi. In the active region, the frictional behaviors of multistranded SS wires compared with other leveling archwires are as follows: (1) coax wires had low friction, (2) triple and rect8 wires had midrange friction, and (3) rect3 wires had high friction. The coefficients of binding (μBI) were not affected by saliva and were proportional to the wire stiffnesses. The resistance to sliding depended on wire stiffnesses to the extent that the differences in the μk-FR's of SS versus NiTi became unimportant shortly after binding occurred. (Am J Orthod Dentofacial Orthop 2002;122:73-83)

Inhibition of dynamic thigh muscle contraction by electrical stimulation of the posterior cruciate ligament in humans.

We investigated the influence of electrical stimulation of the posterior cruciate ligament (PCL) on the motoneuron pool of the thigh muscle during voluntary static and dynamic muscle contraction. The study group comprised nine young men with no history of injury to the knee joints. Multistranded Teflon-insulated stainless-steel wires were inserted into the PCL guided by ultrasound. In three subjects wires were also inserted into the fat pad of the knee. The PCL was electrically stimulated during static, concentric, or eccentric muscle contraction with a constant load of 20% of the maximal voluntary contraction of either the quadriceps or the hamstrings. Electromyographic signals were recorded with bipolar surface electrodes placed over the vastus medialis, rectus femoris, vastus lateralis, biceps femoris caput longum, and semitendinosus muscles. The stimuli consisted of four pulses delivered at 200 HZ; the stimulus amplitude was two to three times the sensory threshold. The electrical stimulation of the PCL inhibited the ongoing muscle activity in both the quadriceps and hamstrings with latencies of 114-150 ms and 99-130 ms, respectively. Stimulation of the fat pad of the knee did not influence the muscle activity. The study suggests that the mechanoreceptors in the PCL are involved in controlling muscle activity during both static and active muscle contractions. The relative long latency of the reflex makes it unlikely that it can serve as a directly protective reflex for the cruciate ligaments.

Clinical comparison and performance perspective of three aligning arch wires

Objectives: To clinically evaluate three commonly used orthodontic tooth aligning arch wires: 016 × 022 inch active martensitic medium force nickel titanium, 016 × 022 inch graded force active martensitic nickel titanium, and 0.0155 inch multistrand stainless steel. Design: A prospective randomized clinical trial. Data source: Measured serial study casts of dental arches for 112 assigned arch wires from 56 consecutive patients. Analysis based on completed records for 98 arch wires and 51 patients. Method: A consecutive sample of 56 patients requiring both upper and lower fixed appliance therapy were randomly allocated two different arch wires from a possible three under trial. Good quality impressions were taken of the dental arches at the designated serial stages of alignment (start, T 0; 4 weeks, T 4; 8 weeks, T 8). The resultant casts were measured on a Reflex Microscope to record the change in individual tooth alignment both in three and two dimensions (horizontal plane only). Results: The measurement error was within acceptable limits (range, 0.05 to 0.09 mm) and showed no significant bias. ANOVA statistical models were fitted to the data to adjust for a number of variables. No significant difference in aligning capability ( p > 0.05), in either two or three dimensions, was demonstrated between the three arch wires in the trial. Conclusion: Heat activated nickel titanium arch wires failed to demonstrate a better performance than the cheaper multistrand stainless steel wires in this randomized clinical trial. The failure to demonstrate in vivo superiority at the clinical level may be due to the confounding effects of large variations in individual metabolic response. Alternatively, it may be that in routine clinical practice NiTi-type wires are not sufficiently deformed to allow their full superelastic properties to come in to play during initial alignment. (Am J Orthod Dentofacial Orthop 1998;114:32-39)

A study of the fatigue properties of small diameter wires used in intramuscular electrodes

Single and multi-strand stainless steel and cobalt-nickel alloy wires, with strand diameters from 26 to 46 microns, were fatigue tested using a modified rotating bending test to determine what factors are most important in controlling fatigue life. The relation between cyclic strain and cyclic life was determined for each material by cyclically straining test specimens at various strain ranges and recording the number of cycles to failure. The results show that (a) the fatigue curves of the 316LVM, MP35N, DBS, and Syntacoben wires are very similar and have many of the same fatigue characteristics of specimens of large cross section. (b) Multi-stranded wires have the same average fatigue life as their individual constituent strands, but the variance of that life is smaller. (c) Deformities in the wire, which are created during the manufacturing, appear to have the effect of shortening the fatigue life of these small section wires. (d) Observation of wire fracture surfaces show a relatively small crack propagation zone and a large fast fracture zone suggesting that most of the fatigue life of these small wires is in the original crack formation, which creates a large stress concentration and quickly leads to wire failure. (e) The size of the wire cross sectional area is of secondary importance compared to the amplitude of the maximum cyclic strain of the individual strands in determining fatigue life of the cable. To maximize the fatigue life of electrodes in vivo, the highest fatigue life for a given bending radius of curvature is desired. This suggests wire strands should be manufactured at the smallest diameter possible (without introducing structural flaws) to maximize service life.

The Construction of Endocardial Balloon Arrays for Cardiac Mapping

The advent of multichannel recording systems has enabled clinical mapping to be performed on a beat-by-beat basis using multi-electrode arrays. Surgical ablation of ventricular arrhythmias generally requires endocardial mapping. Clinical usage has indicated that an inflatable balloon array is the most practical design and can obviate the need for ventriculotomy by a transatrial introduction in the deflated state. Successful experience with the left ventricular balloon led to the development of a right ventricular balloon array suitably configured to extend into the outflow tract. Custom moulds are used to create an appropriate balloon from liquid latex. Nylon cloth is cut from a cardboard pattern to fashion a stretchable sock to envelope the balloon. Electrodes are formed by stitching 2-mm silver beads to the balloon sock in a preconfigured pattern. Teflon-coated 31 G multi-strand stainless-steel wires 130 mm in length connect the electrode beads by solder to the multipin connectors for easy hookup to the amplifier inputs. Tygon tubing 0.53 cm in diameter fitted to the balloon allows inflation and pressure monitoring. This basic design has been successfully implemented for the last 6 years.

Structural responses of orthodontic wires in flexure from a proposed: alternative to the existing specification test

To be reaffirmed in 1987 for lack of a ready replacement, the flexural (elastic-bending) test protocol of ADA Specification No. 32 is judged inadequate. The protocol is problematic because of potentials for erroneous use of the theoretical component, incompatible with the flexible titanium alloy and multistrand stainless steel wires marketed subsequent to the preparation of the specification, and obscure to the clinician because it dictates quantifications of mechanical (pertaining to material only) rather than structural properties (including wire shape and size influences). A five-point elastic-bending test is proposed that simulates wire activation toward engagement of a single, malaligned tooth crown. An experimental study was undertaken to determine values of transverse stiffness and corresponding elastic range for a broad sample of, orthodontic wires and in the process to evaluate the proposed alternative test. Reduced test results are presented; comparisons of rankings and ratios from available theoretical developments and other experimental outcomes, including findings from the existing standard test, were: completed. The difficulties with the existing protocol are largely eliminated with the alternative test; a test fixture and procedures are relatively straightforward to fabricate and follow, and the structural characteristics quantified are more meaningful to the practitioner.

Comparative range of orthodontic wires

ADA specification No. 32 for determining the range (elastic limit) of orthodontic wires uses the bending of a wire section treated as a cantilever beam. An alternative method for defining the range of orthodontic wires proposed by Waters (1981) is to wrap wire sections around mandrels of varying, diameters and measure the deformation imparted after unwrapping. Four brass mandrels with a total of 46 test diameters ranging from 3.5 to 60.0 mm were used in this study. Wire sections 9 cm in length were rolled on the mandrel with a hand lathe. The mandrel cross section required to produce a predetermined amount of deformation (2 mm arc height for a 5 cm chord) was defined as the yield diameter for that particular wire. No individual wire was tested twice so as to avoid introduction of strain history. Test samples of 488 different orthodontic wires supplied by nine commercial distributors were evaluated (a total of 4,747 samples). Stainless steel wires of identical dimensions had a large variation in range, depending on the state of strain hardening and heat treatment. For example, 0.020 inch round wire had yield diameters ranging from 22.8 mm for Australian special plus orange (TP Laboratories) to 42.9 mm for Nubryte gold (G.A,C. International). Chromium cobalt wires had less range than stainless steel before heat treatment, but increased greatly in range after heat treatment. Nitinol (Unitek) had the greatest range of all wires tested (yield diameter of 8.7 mm for 0.016 inch Nitinol). Multistranded stainless steel wires had yield diameters between 9.0 and 14.0 mm.

The effects of electric current on fracture healing clinical observation

The electrical current has been applied for fracture healing. Bared tip, one and half centimeter in length of a multistrand stainless-steel wire insulated with Teflon was inserted into the bone marrow as a cathode and the anode was fixed on the skin. The power pack with 9 volt battery modified to discharge a constant current of 10 microamperes inspite of variable resistence was connected in between both poles. All the patients were sustained either of the fracture of the femur or the tibia.Five patients with non-union, five with delayed union and four with fresh fracture were included in this series. Complete healing of fracture was obtained in thirteen out of fourteen cases. Electrical current thus applied might be said to enhance bone formation and is promising for the treatment of fractures, especially for non-union or delayed union.

Evaluation of multistrand stainless steel wire sutures

A preliminary report has been presented of the characteristics of a new multifilament stainless steel wire suture. It has been found to possess a high degree of flexibility and not to kink. When compared with sutures of silk, cotton and catgut of the same diameter, the wire suture was found to possess greater tensile strength and to cause less tissue reaction in rabbits. A limited clinical trial has been conducted with satisfactory results.