The wires for initial alignment purposes require a combination of excellent strength, excellent springiness, and a long rang of action. The variables in selecting appropriate arches for alignment are the arch wire material, its diameter, and the distance between attachments. The principle that there should be 0.02 inch clearance for initial wires means that an .016 diameter wire is the largest that should be considered for initial alignment in the .018 slot system. The three major possibilities for alignment arches are multistranded steel wires, nickel-titanium wires, and single-stranded steel wires with loops. The excellent choice for initial alignment in .018 bracket is .014 steel wire with loops.
Steel

The purpose of this study was to compare and evaluate the shaping abilities of various hybrid instrumentation method using constant tapered file systems with ProTaper(R) S1 and the difference between experts and inexperienced clinicians in use of NiTi file. Three hybrid methods used in this study were composed of ProTaper(R) S1 and K-Flexofile(R) (group S), ProTaper(R) S1 and HeroShaper(R) (group H), and ProTaper(R) S1 and ProFile(R) (group P), respectively. The ProTaper(R)-alone method (group C) was introduced as a control group. After canal preparation, the lapse of time was recorded. The images of pre- and post-operative canal were scanned and superimposed. Amounts of instrumented canal widths and centering ratio were measured at apical 1, 2 and 3 mm levels and statistical analysis was performed. In this study, both of the group C and S took more time to prepare canals than other groups. Inexperienced operators required more time for the entire preparation with the groups C and H than the experienced (p < 0.05). And the centering ratio of group P were preferable to ProTaper(R)-alone method or the hybrid technique using stainless steel files. As such, within experienced operators, group H also showed better results in addition to the group P. Under these condition, the hybrid methods of each the ProFile(R) system and HeroShaper(R) with ProTaper(R) are recommendable comparative to ProTaper(R)-alone method. According to the results, the hybrid instrumentation method is a more appropriate method of canal preparation than single file system for narrow or curved canals.
Stainless Steel

At a brewery, the base plate-to-shell weld seam of a 90-m3 vertical cylindrical steel tank failed catastrophically. The 4 ton tank "took off" like a rocket leaving its contents behind, and landed on a van, crushing it. The top of the tank reached a height of 30 m. The internal overpressure responsible for the failure was an estimated 60 kPa. A rupture disc rated at < 50 kPa provided overpressure protection and thus prevented the tank from being covered by the European Pressure Equipment Directive. This safeguard failed and it was later discovered that the rupture disc had been installed upside down. The organizational root cause of this incident may be a fundamental lack of appreciation of the hazards of large volumes of low-pressure compressed air or gas. A contributing factor may be that the standard piping and instrumentation diagram (P&ID) symbol for a rupture disc may confuse and lead to incorrect installation. Compressed air systems are ubiquitous. The medium is not toxic or flammable. Such systems however, when operated at "slight overpressure" can store a great deal of energy and thus constitute a hazard that ought to be addressed by safety managers.
Compressed Air ; Rupture* ; Steel*

OBJECTIVES: To determine the actual revolutions per minute (rpm) values and compare the cyclic fatigue life of Reciproc (RPC, VDW GmbH), WaveOne (WO, Dentsply Maillefer), and TF Adaptive (TFA, Axis/SybronEndo) nickel-titanium (NiTi) file systems using high-speed camera. MATERIALS AND METHODS: Twenty RPC R25 (25/0.08), 20 WO Primary (25/0.08), and 20 TFA ML 1 (25/0.08) files were employed in the present study. The cyclic fatigue tests were performed using a dynamic cyclic fatigue testing device, which has an artificial stainless steel canal with a 60° angle of curvature and a 5-mm radius of curvature. The files were divided into 3 groups (group 1, RPC R25 [RPC]; group 2, WO Primary [WO]; group 3, TF Adaptive ML 1 [TFA]). All the instruments were rotated until fracture during the cyclic fatigue test and slow-motion videos were captured using high-speed camera. The number of cycles to failure (NCF) was calculated. The data were analyzed statistically using one-way analysis of variance (ANOVA, p < 0.05). RESULTS: The slow-motion videos were indicated that rpm values of the RPC, WO, and TFA groups were 180, 210, and 425, respectively. RPC (3,464.45 ± 487.58) and WO (3,257.63 ± 556.39) groups had significantly longer cyclic fatigue life compared with TFA (1,634.46 ± 300.03) group (p < 0.05). There was no significant difference in the mean length of the fractured fragments. CONCLUSIONS: Within the limitation of the present study, RPC and WO NiTi files showed significantly longer cyclic fatigue life than TFA NiTi file.
Fatigue* ; Radius ; Stainless Steel

OBJECTIVES: To compare the fatigue life of Tango-Endo, WaveOne GOLD, and Reciproc NiTi instruments under static model via artificial canals with different angles of curvature. MATERIALS AND METHODS: Reciproc R25, WaveOne GOLD Primary, and Tango-Endo instruments were included in this study (n = 20). All the instruments were rotated in artificial canals which were made of stainless steel with an inner diameter of 1.5 mm, 45°, 60°, and 90° angles of curvatures and a radius of curvature of 5 mm until fracture occurred, and the time to fracture was recorded in seconds using a digital chronometer. The data were analyzed using Kruskal-Wallis and post-hoc Dunn tests were used for the statistical analysis of data in SPSS 21.0 software. RESULTS: Tango-Endo files were found to have significantly higher values than WaveOne GOLD and Reciproc files in terms of fatigue life (p < 0.05). However, there was no statistically significant difference between fatigue life of Reciproc and WaveOne GOLD files (p > 0.05). It was determined that increasing the angle of curvature of the stainless canals caused significant decreases in fatigue life of all of three files (p < 0.05). CONCLUSIONS: Within the limitations of the present study, the cyclic fatigue life of Tango-Endo in canals having different angles of curvature was statistically higher than Reciproc and WaveOne GOLD.
Fatigue* ; Radius ; Stainless Steel

This report introduces a novel technique that allows a safe and predictable canal negotiation, creation of a glide path and canal preparation with reciprocating nickel-titanium or stainless steel engine-driven instruments in canals where the use of rotary and the newly developed reciprocating instruments is contraindicated. In this novel technique, the instruments are used in reciprocating motion with very small angles. Hand files are not used regardless of the complexity of the canal anatomy. It also allows achieving predictable results in canal negotiation and glide path creation in challenging canals without the risk of instrument fracture.
Hand ; Negotiating ; Stainless Steel*

OBJECTIVE: To quantify, for each activation, the effect of preactivations of differing distribution and intensity on the neutral position of T-loops (7-mm height), specifically the horizontal force, moment to force (M/F) ratio, and load to deflection ratio. METHODS: A total 100 loops measuring 0.017 x 0.025 inches in cross-section were divided into two groups (n = 50 each) according to composition, either stainless steel or beta-titanium. The two groups were further divided into five subgroups, 10 loops each, corresponding to the five preactivations tested: preactivations with occlusal distribution (0degrees, 20degrees, and 40degrees), gingival distribution (20degrees), and occlusal-gingival distribution (40degrees). The loops were subjected to a total activation of 6-mm with 0.5-mm iterations. Statistical analysis was performed using comprised ANOVA and Bonferoni multiple comparison tests, with a significance level of 5%. RESULTS: The location and intensity of preactivation influenced the force intensity. For the M/F ratio, the highest value achieved without preactivation was lower than the height of the loop. Without preactivation, the M/F ratio increased with activation, while the opposite effect was observed with preactivation. The increase in the M/F ratio was greater when the preactivation distribution was partially or fully gingival. CONCLUSIONS: Depending on the preactivation distribution, displacement of uprights is higher or lower than the activation, which is a factor to consider in clinical practice.
Analysis of Variance ; Stainless Steel*

Stainless steel has been widely used in non-active surgical implantable medical device of cardiovascular, orthopedics, dental and ophthalmology. In this paper, we mainly focused on development of stainless steel, as well as the material-related standard evolution. We further summarized the recent advancement of stainless steel use in surgical implantable medical device. Insight and regulatory perspective has been further demonstrated.
Prostheses and Implants ; Stainless Steel

The aim of this study was to compare the morphological characteristics of two types of stainless steel permanent molar crowns using three-dimensional scanners and the morphological changes of these crowns after crimping. Two types of stainless steel permanent molar crowns, PO-96 and PERMACROWN were scanned using three-dimensional scanner. Crown size, crown index (ratio of buccolingual diameter to mesiodistal diameter at height of contour), cervical convergency of crown were measured. Stainless steel crowns were crimped and re-scanned with three-dimensional scanner. Morphological changes of stainless steel permanent molar crowns were analyzed. As for the crown index, maxillary PERMACROWN was larger buccolingually and smaller mesiodistally than maxillary PO-96 and mandibular PERMACROWN was smaller buccolingually and larger mesiodistally than mandibular PO-96. Maxillary PO-96 was more convergent to cervical mesiodistally than maxillary PERMACROWN and mandibular PO-96 was more convergent to the cervical mesiodistally, buccolingually than mandibular PERMACROWN. Both types of stainless steel permanent molar crowns showed reduction of cervical circumference after crimping. Two products were morphologically different in crown size, shape and cervical convergence. Although both types of stainless steel permanent molar crowns are pre-contoured type, additional crimping is needed to achieve better marginal adaptation.
Crowns ; Molar ; Stainless Steel

The purpose of this study was to find the difference of stress distribution on canine altered by the application point of preangulated T-loop spring T-loop spring. For this study, the finite element models of upper left canine, upper left second premolar and upper left first molar were made. Also, the finite element models of 0.017X0.025 inch preangulated, preactivated T-loop spring and 0.018X0.025 inch stainless steel wire were made. Three types of T-loop spring were made : the middle of activated T-loop is positioned in accordance with the middle position of distance of bracket position of both the canine and first molar, 2mm anterior, 2mm posterior. We compared the forces and the distribution of stress that were generated by the difference of position of T-loop spring. The results were as follows. 1. All of the 3 types of T-loop spring showed the similar retraction forces. 2. All showed the similar amount & pattern of stress distribution. 3. The centers of rotation of canine in 3 types of T-loop spring were same and were positioned between C and D plane. 4. The canine showed the intrusive force by 2mm anterior positioned T-loop spring, but the extrusive force by 2mm posterior positioned T-loop spring. Neverthless, because of the small amount of the forces, the effect of vertical force was not significant.
Bicuspid ; Molar ; Stainless Steel