scholarly journals Friction Between Metallic Brackets Before and After Clinical Use: A Comparative Study

2017 ◽  
pp. 40-43
Author(s):  
Anna Paula Costa Ponte Sousa ◽  
Rafael Ferreira Freire ◽  
Nathalia Carolina Fernandes Fagundes ◽  
Rogério Bentes Kato ◽  
Marcelo Azenha ◽  
...  
Keyword(s):  
Comparative Study ◽  
Friction Force ◽  
Frictional Force ◽  
Clinical Use ◽  
Control Groups ◽  
Orthodontic Wires ◽  
Anova Test ◽  
Orthodontic Wire ◽  
Oral Environment ◽  
Before And After

The friction is a factor that can result on changes in efficacy of sliding orthodontic mechanics. Different factors can impact on the friction force: the composition and properties of orthodontic wires and brackets, the cleaning of orthodontic braces, and even saliva. This study aimed to evaluate the friction in two brands before and after use in the oral environment. Ten patients from the orthopedic clinic of the Master’s of Dentistry, with two premolars bonded of each patient. The patients were divided, according with total number of brackets (n= 40): 2 control groups - without exposure to the buccal medium - (G1 and G2) and 2 experimental groups - with exposure to the buccal medium - (G3 and G4). The brackets were testes on a friction machine and evaluated in a two-way ANOVA test. It was observed that the brand used in groups G2 and G4 presented greater friction with the orthodontic wire and the G2 group brackets presented similar frictional force to G3, which had already been exposed to clinical use. Brazilian brackets brands presented an increased friction after clinical use.

scholarly journals Mechanical properties of orthodontic wires covered with a polyether ether ketone tube

2018 ◽  
Vol 88 (4) ◽  
pp. 442-449 ◽  
Author(s):  
Nobukazu Shirakawa ◽  
Toshio Iwata ◽  
Shinjiro Miyake ◽  
Takero Otuka ◽  
So Koizumi ◽  
...  
Keyword(s):  
Frictional Force ◽  
Color Difference ◽  
Orthodontic Appliances ◽  
Orthodontic Wires ◽  
Polyether Ether Ketone ◽  
Orthodontic Wire ◽  
Before And After ◽  
Ether Ketone ◽  
Coated Wires ◽  
Almost All

ABSTRACT Objectives: To evaluate the esthetics and frictional force of an orthodontic wire passed through a newly designed tube made of a polyether ether ketone (PEEK) resin. Materials and Methods: Two types of standard PEEK tubes were prepared at 0.5 × 0.6ф and 0.8 × 0.9ф, and different archwires were passed through the tubes. Color values were determined according to brightness and hues. Friction was assessed with different bracket-wire combinations, and surface roughness was determined by stereomicroscopy before and after the application of friction. Results: The PEEK tube showed a color difference that was almost identical to that of coated wires conventionally used in clinical practice, indicating a sufficient esthetic property. The result of the friction test showed that the frictional force was greatly reduced by passing the archwire through the PEEK tube in almost all of the archwires tested. Conclusions: Use of the new PEEK tube demonstrated a good combination of esthetic and functional properties for use in orthodontic appliances.

scholarly journals Debris and friction of self-ligating and conventional orthodontic brackets after clinical use

2014 ◽  
Vol 85 (4) ◽  
pp. 673-677 ◽  
Author(s):  
Raíssa Costa Araújo ◽  
Lívia Monteiro Bichara ◽  
Adriana Monteiro de Araujo ◽  
David Normando
Keyword(s):  
Frictional Force ◽  
The Self ◽  
Orthodontic Brackets ◽  
Rank Test ◽  
Clinical Use ◽  
Clinical Exposure ◽  
Debris Accumulation ◽  
Before And After ◽  
Conventional Brackets ◽  
Signed Rank Test

ABSTRACT Objective:  To compare the degree of debris and friction of conventional and self-ligating orthodontic brackets before and after clinical use. Materials and Methods:  Two sets of three conventional and self-ligating brackets were bonded from the first molar to the first premolar in eight individuals, for a total of 16 sets per type of brackets. A passive segment of 0.019 × 0.025-inch stainless steel archwire was inserted into each group of brackets. Frictional force and debris level were evaluated as received and after 8 weeks of intraoral exposure. Two-way analysis of variance and Wilcoxon signed-rank test were applied at P < .05. Results:  After the intraoral exposure, there was a significant increase of debris accumulation in both systems of brackets (P < .05). However, the self-ligating brackets showed a higher amount of debris compared with the conventional brackets. The frictional force in conventional brackets was significantly higher when compared with self-ligating brackets before clinical use (P < .001). Clinical exposure for 8 weeks provided a significant increase of friction (P < .001) on both systems. In the self-ligating system, the mean of friction increase was 0.21 N (191%), while 0.52 N (47.2%) was observed for the conventional system. Conclusion:  Self-ligating and conventional brackets, when exposed to the intraoral environment, showed a significant increase in frictional force during the sliding mechanics. Debris accumulation was higher for the self-ligating system.

scholarly journals In vitro evaluation of frictional force of a novel elastic bendable orthodontic wire

2018 ◽  
Vol 88 (5) ◽  
pp. 602-610
Author(s):  
Megumi Takada ◽  
Akira Nakajima ◽  
Shingo Kuroda ◽  
Shinya Horiuchi ◽  
Noriyoshi Shimizu ◽  
...  
Keyword(s):  
Frictional Force ◽  
Frictional Resistance ◽  
The Novel ◽  
Orthodontic Wires ◽  
Alloy Wire ◽  
Orthodontic Wire ◽  
Ni Alloy ◽  
Titanium Nickel ◽  
Elastic Modules

ABSTRACT Objectives: To determine the frictional force (FF) of the novel, elastic, bendable titanium-niobium (Ti-Nb) alloy orthodontic wire in stainless steel (SS) brackets and to compare it with those of titanium-nickel (Ti-Ni) and titanium-molybdenum (Ti-Mo) alloy wires. Materials and Methods: Three sizes of Ti-Nb, Ti-Ni, and Ti-Mo alloy wires were ligated with elastic modules to 0.018-inch and 0.022-inch SS brackets. The dynamic FFs between the orthodontic wires and SS brackets were measured at three bracket-wire angles (0°, 5°, and 10°) with an Instron 5567 loading apparatus (Canton, Mass). Results: FFs increased gradually with the angle and wire size. In the 0.018-inch-slot bracket, the dynamic FFs of Ti-Nb and Ti-Ni alloy wires were almost the same, and those of the Ti-Mo alloy wire were significantly greater (P<0.05). FF values were 1.5–2 times greater in the 0.022-inch-slot bracket than in the 0.018-inch-slot bracket, regardless of alloy wire type, and the Ti-Mo alloy wire showed the greatest FF. Scanning electric microscopic images showed that the surface of the Ti-Mo alloy wire was much rougher than that of the Ti-Ni and Ti-Nb alloy wires. Conclusion: These findings demonstrate that the Ti-Nb alloy wire has almost the same frictional resistance as the Ti-Ni alloy wire, although it has a higher elastic modulus.

Friction reduction and wear resistance of electro-co-deposited inorganic fullerene-like WS2 coating for improved stainless steel orthodontic wires

2008 ◽  
Vol 23 (11) ◽  
pp. 2909-2915 ◽  
Author(s):  
Meir Redlich ◽  
Alex Gorodnev ◽  
Yishay Feldman ◽  
Ifat Kaplan-Ashiri ◽  
Reshef Tenne ◽  
...  
Keyword(s):  
Friction Force ◽  
Metal Nanoparticle ◽  
Friction Reduction ◽  
Orthodontic Wires ◽  
Tungsten Disulphide ◽  
Inorganic Fullerene ◽  
Before And After ◽  
New Type ◽  
Coated Wires ◽  
Coated Surfaces

A new type of composite metal–nanoparticle coating that significantly reduces the friction force of various surfaces, particularly archwires in orthodontic applications, is demonstrated. The coating is based on electrodeposited Ni film impregnated with inorganic fullerene-like nanospheres of tungsten disulphide. The first encouraging tests have shown reduction of up to 60% of the friction force between coated rectangular archwires and self-ligating brackets in comparison with uncoated archwires. The coating not only significantly reduces friction of commercial archwires but also maintains this low value of friction for the duration of the tests in comparison to archwires coated with nickel film without the nanoparticles. The coated surfaces of the wires were examined by scanning electron microscopy equipped with energy dispersive analyzer and by x-ray powder diffraction methods before and after the friction tests. Using these analyses, it was possible to qualitatively estimate the state of the Ni+IF-WS2 coating before and after the friction test compared to Ni coated wires without IF-WS2.

Composition and Transitional Temperature Range of Several Nickel-Titanium Alloy Wires in Orthodontic Treatment

2011 ◽  
Vol 87 ◽  
pp. 20-25 ◽  
Author(s):  
Rutchadakorn Isarapatanapong ◽  
Surachai Dechkunakorn ◽  
Niwat Anuwongnukroh ◽  
Nattiree Chiranavanit ◽  
Julathep Kajorchaiyakul ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Orthodontic Treatment ◽  
Nickel Titanium ◽  
Clinical Use ◽  
Scanning Calorimetry ◽  
Orthodontic Wires ◽  
X Ray ◽  
Temperature Range ◽  
Oral Environment ◽  
Scanning Electron

Objective: The study aimed to clarify the compositions of 14 brands of superelastic NiTi orthodontic wires. Materials and Methods: The compositions were analysed through scanning electron microscopy and energy-dispersive X-ray microanalysis. The wires were tested in differential scanning calorimetry to find the transitional temperature range. Results: The compositions were nickel (50.085%-51.605%), titanium (46.675%-48.140%), copper (0.995%-1.155%), aluminum (0.220%-1.325%), chromium (0%-0.275%) and iron (0%-0.030%). None contained cobalt. G&H, Ormco, AMDG, IMD, Smart, TruFlex, Force 1, NIC, Sentalloy, Ortho Supply and Flexwire were almost or completely austenitic in the oral environment, whereas Highland, Grikin and Unitex were a mixture of austenitic and martensitic phase. The wires showed austenitic finish temperatures ranging from 17°C to 59°C. Conclusions: The results show that NiTi orthodontic arch wires have differences in composition and phase transformation. This information is valuable to evaluate differences in NiTi orthodontic wires for clinical use.

Effects of Time and Perceptual Orientation on Actors' and Observers' Attributions

1984 ◽  
Vol 58 (1) ◽  
pp. 23-30
Author(s):  
Donald S. Martin ◽  
Ming-Shiunn Huang
Keyword(s):  
Video Recording ◽  
Control Group ◽  
Control Groups ◽  
Video Recordings ◽  
Before And After ◽  
Perceptual Orientation ◽  
Initial Difference ◽  
Variety Show ◽  
And Control ◽  
Unrelated Variety

The actor/observer effect was examined by Storms in a 1973 study which manipulated perceptual orientation using video recordings. Storms' study was complex and some of his results equivocal. The present study attempted to recreate the perceptual reorientation effect using a simplified experimental design and an initial difference between actors and observers which was the reverse of the original effect. Female undergraduates performed a motor co-ordination task as actors while watched by observers. Each person made attributions for the actor's behaviour before and after watching a video recording of the performance. For a control group the video recording was of an unrelated variety show excerpt. Actors' initial attributions were less situational than observers'. Both actors and observers became more situational after the video replay but this effect occurred in both experimental and control groups. It was suggested the passage of time between first and second recording of attributions could account for the findings and care should be taken when interpreting Storms' (1973) study and others which did not adequately control for temporal effects.

scholarly journals Robust Inferences from a Before-and-After Study with Multiple Unaffected Control Groups

2013 ◽  
Vol 1 (2) ◽  
pp. 209-234 ◽  
Author(s):  
Pengyuan Wang ◽  
Mikhail Traskin ◽  
Dylan S. Small
Keyword(s):  
Sensitivity Analysis ◽  
Control Groups ◽  
Two Stage ◽  
Time Effects ◽  
Unaffected Control ◽  
Group Time ◽  
Before And After ◽  
Group Variation ◽  
The Impact ◽  
Before And After Study

AbstractThe before-and-after study with multiple unaffected control groups is widely applied to study treatment effects. The current methods usually assume that the control groups’ differences between the before and after periods, i.e. the group time effects, follow a normal distribution. However, there is usually no strong a priori evidence for the normality assumption, and there are not enough control groups to check the assumption. We propose to use a flexible skew-t distribution family to model group time effects, and consider a range of plausible skew-t distributions. Based on the skew-t distribution assumption, we propose a robust-t method to guarantee nominal significance level under a wide range of skew-t distributions, and hence make the inference robust to misspecification of the distribution of group time effects. We also propose a two-stage approach, which has lower power compared to the robust-t method, but provides an opportunity to conduct sensitivity analysis. Hence, the overall method of analysis is to use the robust-t method to test for the overall hypothesized range of shapes of group variation; if the test fails to reject, use the two-stage method to conduct a sensitivity analysis to see if there is a subset of group variation parameters for which we can be confident that there is a treatment effect. We apply the proposed methods to two datasets. One dataset is from the Current Population Survey (CPS) to study the impact of the Mariel Boatlift on Miami unemployment rates between 1979 and 1982.The other dataset contains the student enrollment and grade repeating data in West Germany in the 1960s with which we study the impact of the short school year in 1966–1967 on grade repeating rates.

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