Search results for "racket"
showing 10 items of 132 documents
In vitro bond strengths post thermal and fatigue load cycling of sapphire brackets bonded with self-etch primer and evaluation of enamel damage
2020
Background This in vitro study compares a self-etch primer (SEP) to an etch-and-rinse (EaR) for bonding sapphire brackets by evaluation of the enamel etch-pattern, shear bond strength, amount of remnant adhesive and enamel surface damage following thermal and fatigue cyclic loading. Material and Methods Ceramic (sapphire) brackets were bonded to 80 extracted human premolars using two enamel etching protocols: conventional EaR using 37% phosphoric acid (PA) gel (control), and a SEP (Transbond Plus). Each group was subdivided into two subgroups (n=20 teeth) according to the time of bracket debonding: after 24 h water storage or following 5000 thermo-cycles plus 5000 cycles fatigue loading, to…
The effect of different force magnitudes for placement of orthodontic brackets on shear bond strength, in three adhesive systems.
2018
Background: Amount of pressure exerting on orthodontic brackets during bonding can create different thickness of adhesive and affect shear bonding strength(SBS) in different adhesive systems. The purpose of this study was to evaluate the effect of different force magnitudes for placement of brackets on SBS. Material and Methods: In an in vitro study, 420 brackets were placed on the bovine teeth, using three types of adhesives, Concise (chemically cured two-paste mix), Unite (chemically cured no mix), and Transbond XT( light cured), with the application of seven force magnitudes of 50, 100, 200, 300, 400, 600 and 1000 grams in twenty-one groups of twenty samples each. SBS means (using two-wa…
Comparative evaluation of orthodontic bracket base shapes on shear bond strength and adhesive remnant index : an in vitro study
2017
BACKGROUND The objective of this study was to evaluate the effect of orthodontic bracket base shape on shear bond strength and adhesive remnant index. MATERIAL AND METHODS In this in vitro study using 140 bovine incisors, shear bond strength (SBS) of brackets with different base shapes (rectangle, flower, round, heart, diamond, star, and football) were measured with an Instron testing machine and tested until bond failure. Adhesive Remnant Index (ARI) scoring was evaluated after debonding to evaluate the location of bond failure. Descriptive and one-way ANOVA post-hoc Tukey statistical analyses were performed with a statistical significance set at p≤0.05. RESULTS Statistically significant d…
The impact of different surface treatments on the shear bond strength of orthodontic metal brackets applied to different CAD/CAM composites
2020
Background To investigate the shear bond strength (SBS) of orthodontic metal brackets applied to different CAD/CAM composites treated with different surface treatments. Material and Methods Specimens of two CAD/CAM composites were obtained of Lava Ultimate (LU; n=60) and Brilliant Crios (BC; n=60) which were randomly separated into six subgroups (n=10) according to the surface treatment: control (CTL); sandblasting (SB); sandblasting and silane (SBSL); hydrofluoric acid (HF); hydrofluoric acid and silane (HFSL); and Monobond Etch&Prime (MEP). The mandibular central incisor metal brackets were bonded with a light-cure adhesive. The SBS data were analyzed using the two-way analysis of varianc…
Enamel evaluation by scanning electron microscopy after debonding brackets and removal of adhesive remnants
2017
Made available in DSpace on 2022-04-29T08:27:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-01 Background: The bonding of accessories in the dental crown during the orthodontic treatment creates microporosities, thus promoting micromechanical retention of the adhesive to the enamel structure. After debonding brackets, at the end of the active orthodontic treatment, a certain amount of adhesive remnants must be mechanically removed from the enamel. The objective of this study was to compare, by means of scanning electron microscopy, three different methods to remove the adhesive remnants after orthodontic bracket removal. Material and Methods: An experimental analytical study w…
Effect of addition of bioactive glass to resin modified glass ionomer cement on enamel demineralization under orthodontic brackets
2019
Background Enamel demineralization and white spot lesions around orthodontic brackets is a common problem associated with fixed orthodontic treatment. Glass ionomer cements (GICs) are commonly used for bracket bonding and recently, bioactive glass (BAG) was added to GICs to enhance deposition of calcium phosphate in adjacent dental structure. This study sought to assess the effect of addition of BAG particles to resin modified GIC (RMGIC) on enamel demineralization under orthodontic brackets. Material and methods In this in vitro, experimental study, 60 sound human premolars were immersed in distilled water at 6°C. The teeth were randomly divided into three groups. Using a sticker, a window…
Effects of recycling and bonding agent application on bond strength of stainless steel orthodontic brackets
2014
Objectives: 1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. Study Design: A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in each of the first four groups while the last one (group V) was used as the control. Groups (I-V) were subjected to shear force within half an hour until the brackets debond. SBS was measured and the me…
Comparison of frictional forces during the closure of extraction spaces in passive self-ligating brackets and conventionally ligated brackets using t…
2019
Background This study compared the frictional force resulting from the bracket/archwire interface and the stress at the root/periodontal ligament/bone interface, between passive self-ligating brackets and conventionally ligated brackets, during the space closure stage. Material and methods A cone beam tomography was taken to a female patient that required extraction of upper first premolars and passive self-ligating system; three months after its activation, a cone beam tomography was taken again. The designs of the maxillary bone and the entire system were possible through tomography images and stereomicroscopic photographs. Validation of the Finite Element Method (FEM) was achieved compar…
Does mechanical locking-base ceramic brackets reduce cracks at debonding?
2012
Objectives: Debonding of chemically bonded ceramic brackets has been mostly led to enamel damages. This study aimed to evaluate enamel cracks followed by debonding ceramic brackets with mechanical retention. Study Design: Sixty extracted human premolar teeth were randomly divided into two groups. Metallic brackets and recently available ceramic brackets with mechanical retention were bonded to the teeth in first (MB) and second (CB) group respectively. After a week, the brackets were debonded using a pair of bracket-removing pliers assembled to a testing machine. Optical stereomicroscope and trans-illumination techniques were used to calculate the cracks and measure their length before bond…
Deformations of semisimple Poisson pencils of hydrodynamic type are unobstructed
2015
We prove that the bihamiltonian cohomology of a semisimple pencil of Poisson brackets of hydrodynamic type vanishes for almost all degrees. This implies the existence of a full dispersive deformation of a semisimple bihamiltonian structure of hydrodynamic type starting from any infinitesimal deformation.