Search results for "Racket"
showing 10 items of 132 documents
Survey on awareness and preference of ceramic bracket debonding techniques among orthodontists
2020
Background The objectives of this study was to evaluate the awareness of different ceramic bracket debonding techniques among orthodontists in the USA and the most commonly used debonding technique for ceramic bracket removal. Material and methods A survey on preference for debonding and awareness of debonding techniques was emailed to 2,227 members of the American Association of Orthodontists (AAO). Results 119 orthodontists completed the survey. 111 responses were included in the study analysis of ceramic bracket users. The most common technique used was mechanical debonding. 86.5% used a specially designed bracket removing plier from the manufacturer. Overall, there were 59.5% of surveye…
Rates of tooth movement and bone remodeling activity : self-ligating versus conventional brackets
2019
Background Bracket systems have been developed with the purpose of reducing frictional resistance between the archwire and accessories. The aim of this research was to compare rates of tooth movement and regions of cellular bone modeling activity along tooth root surfaces of teeth moved with conventional vs. self-ligating brackets. Material and Methods The experiments were conducted in 20 male dogs. Bands were cemented in all intermediate incisors, with conventional brackets (Morelli) on the right side and hybrid self-ligating ones (T3-American Orthodontics) on the left side. A 0.019” x 0.025” stainless steel wire was inserted passively in the slot of these brackets with chain elastics (250…
Comparison of torque expression in esthetic brackets
2019
Background The objective of this work is to test the null hypothesis that there is no difference in the torque expression among different esthetic brackets. Material and methods Five ceramic self-ligating brackets (In-Ovation C - GAC, Damon Clear-Ormco, QuicKlear-Forestadent, Click-It -TP Orthodontics, Clarity SL-3M Unitek) and 4 ceramic conventional brackets (Inspire Ice-Ormco, InVu Ceramic-TP Orthodontics, Ceramic Roth-Morelli, Clarity Metal-Reinforced Ceramic Bracket-3M Unitek) were selected. Metallic Damon MX self-ligating bracket (Ormco) was used as control. Third-order moments were measured at 12o, 24o and 36o using an archwire torsion device associated with a Universal Testing Machin…
The effect of dental chair light exposure duration on shear bond strength of orthodontic brackets : an in vitro study
2018
Background The purpose of this study is to determine if the duration of exposure to the halogen overhead dental chair light has an effect on shear bond strength (SBS) of metal orthodontic brackets. Material and Methods One hundred twenty extracted human lower incisor teeth were divided into six groups (n=20/group). Each group was assigned a predetermined duration of exposure to the halogen dental chair light, set at a fixed distance, before being cured. Light exposure times of 0 minutes (Group 1-Control), 1 minute (Group 2), 2.5 minutes (Group 3), 5 minutes (Group 4), 10 minutes (Group 5), and 15 minutes (Group 6) were tested. Each tooth was subjected to an exclusion criteria examination, s…
Orthodontic brackets friction changes after clinical use : a systematic review
2019
Background To evaluate the bracket-wire friction force after clinical use. Material and methods A systematic search of several electronic databases (PubMed, Embase, Web of Science, Scopus, The Cochrane Library, Lilacs and Google Scholar) without limitations regarding publication year or language, was performed. In-vitro studies analyzing the changes in friction force of orthodontic brackets before/after their clinical use were considered. Risk of Bias was assessed with Downs and Black checklist. All methodological features that could interfere in the results were specifically described. Results Seven studies satisfied the inclusion criteria and were included in the review. All 7 studies rep…
Practice of lingual orthodontics and practitioners’ opinion and experience with lingual braces in the United States
2020
Background A survey was done on practicing Orthodontists in the United States on their experience with lingual orthodontics. The objectives of this survey study were to assess 1) the satisfaction level with cases treated with lingual orthodontics, 2) factors that influence clinicians' decision to utilize or not utilize lingual braces in their current practices, and 3) intention of using lingual braces in their future practices, if not used currently, in the U.S. Material and methods A survey questionnaire was electronically distributed to 2,200 active U.S. members of the American Association of Orthodontists (AAO). Results 85 orthodontists completed the survey. About 25% of respondents prac…
The Poisson Bracket Structure of the SL(2, R)/U(1) Gauged WZNW Model with Periodic Boundary Conditions
2000
The gauged SL(2, R)/U(1) Wess-Zumino-Novikov-Witten (WZNW) model is classically an integrable conformal field theory. A second-order differential equation of the Gelfand-Dikii type defines the Poisson bracket structure of the theory. For periodic boundary conditions zero modes imply non-local Poisson brackets which, nevertheless, can be represented by canonical free fields.
An alternative formulation of Classical Mechanics based on an analogy with Thermodynamics
2013
We study new Legendre transforms in classical mechanics and investigate some of their general properties. The behaviour of the new functions is analyzed under coordinate transformations.When invariance under different kinds of transformations are considered, the new formulation is found to be completly equivalent to the usual Lagrangian formulation, recovering well established results like the conservation of the angular momentum. Furthermore, a natural generalization of the Poisson Bracket is found to be inherent to the formalism introduced. On the other hand, we find that with a convenient redefinition of the Lagrangian, $\mathcal{L}^{\prime}=-\mathcal{L}$, it is possible to establish an …
Classical Chern–Simons Mechanics
2001
We are interested in a completely integrable Hamiltonian system \((\mathscr{M}_{2N},\omega,H).\) Local coordinates on the 2N-dimensional phase space \(\mathscr{M}_{2N}\) are denoted by η a = (p, q), a = 1, 2, … 2N and the symplectic 2-form ω is given by
Classical and Quantum Nonultralocal Systems on the Lattice
1997
We classify nonultralocal Poisson brackets for 1-dimensional lattice systems and describe the corresponding regularizations of the Poisson bracket relations for the monodromy matrix. A nonultralocal quantum algebras on the lattices for these systems are constructed. For some class of such algebras an ultralocalization procedure is proposed. The technique of the modified Bethe-Anzatz for these algebras is developed and is applied to the nonlinear sigma model problem.