Search results for "Adhesive"
showing 10 items of 299 documents
POSITIONING SELF-ETCHING ADHESIVES: VERSUS OR IN ADDITION TO PHOSPHORIC ACID ETCHING?
2004
Effect of water contamination on the shear bond strength of five orthodontic adhesives
2010
Objectives: To evaluate the shear bond strength and site of failure of brackets bonded to dry and wet enamel. Study design: 50 teeth were divided into ten groups of 5 teeth each (10 surfaces). In half the groups enamel was kept dry before bonding, and in the other half distilled water was applied to wet the surface after etching. The following groups were established: 1)Acid/Transbond-XT (dry/wet) XT; 2) Transbond Plus Self Etching Primer (TSEP)/Transbond-XT paste (dry/wet); 3) Concise (dry), Transbond MIP/Concise (wet), 4) FujiOrtho-LC (dry/ wet); 5) SmartBond (dry/wet). Brackets were bonded to both buccal and lingual surfaces. Specimens were stored in distilled water (24 hours at 37ºC) an…
Casein phosphopeptide-amorphous calcium phosphate effects on brackets shear bond strength and enamel damage
2017
Background The aim of study was to evaluate the application of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride regarding their effect on the shear bond strength (SBS), bond failure pattern of brackets using the adhesive remnant index (ARI) and assessing the quality of enamel surface using the enamel damage index (EDI). Material and methods Sixty extracted premolar teeth were randomly divided into four groups regarding pretreatment application of CPP-ACP and fluoride. Brackets were bonded using the conventional method. Specimens were thermocycled for 1000 cycles and were subsequently tested for the SBS in a universal testing machine. After debonding, the teeth were e…
Cohesive delamination and frictional contact on joining surface via XFEM
2018
In the present paper, the complex mechanical behaviour of the surfaces joining two different bodies is analysed by a cohesive-frictional interface constitutive model. The kinematical behaviour is characterized by the presence of discontinuous displacement fields, that take place at the internal connecting surfaces, both in the fully cohesive phase and in the delamination one. Generally, in order to catch discontinuous displacement fields, internal connecting surfaces (adhesive layers) are modelled by means of interface elements, which connect, node by node, the meshes of the joined bodies, requiring the mesh to be conforming to the geometry of the single bodies and to the relevant connectin…
Resistance of bonded premolars to four artificial ageing models post enamel conditioning with a novel calcium-phosphate paste
2020
Background This in vitro study compares a novel calcium-phosphate etchant paste to conventional 37% phosphoric acid gel for bonding metal and ceramic brackets by evaluating the shear bond strength, remnant adhesive and enamel damage following water storage, acid challenge and fatigue loading. Material and Methods Metal and ceramic brackets were bonded to 240 extracted human premolars using two enamel conditioning protocols: conventional 37% phosphoric acid (PA) gel (control), and an acidic calcium-phosphate (CaP) paste. The CaP paste was prepared from β-tricalcium phosphate and monocalcium phosphate monohydrate powders mixed with 37% phosphoric acid solution, and the resulting phase was con…
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…
Local Reinforcement Effect of a Strain Gauge Installation on Low Modulus Materials
2005
The reinforcement effect of electrical resistance strain gauges is well documented in the technical literature. In this paper the local reinforcement effect in tension is studied by using a simple theoretical model by considering a strain gauge mounted on a semi-infinite plate having the same width of the strain gauge and subjected to a uniaxial tension load. Neglecting the effect of the adhesive layer and considering the interface shear stress as an exponential distribution, the proposed model gives a closed-form solution. In detail, this model permits a simple formula to be obtained which allows the user to correct the local reinforcement effect provided that a proper calibration is perfo…
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…
Use of kinetic DTA and TG methods for compatibility tests on 2,4,6--trinitrotoluene
1986
We have investigated the suitability of thermoanalytical methods for compatibility tests on explosives and contact materials. DTA and TG curves of various materials were evaluated using two DTA and four TG methods and one DSC method. TNT was used as model substance. The contact materials were paraffin, polyethylene, an epoxy resin paint and an epoxy glue. In earlier tests the first two were found compatible and the latter two incompatible with TNT. None of the methods provides an absolute value for the activation energy. However, in compatibility tests only the relative change in the activation energy is of interest and, for this, three of the methods proved informative.
Surface investigation of adhesive formulation consisting of UV sensitive triblock poly(styrene–b-butadiene–b-styrene) copolymer
2002
Abstract Atomic force microscopy (AFM) analysis in conjunction with macroscopic studies such as peel testing and contact angle measurement have been undertaken to explain the nanomechanical properties of adhesive formulation consisting of triblock poly(styrene–b-butadiene–b-styrene) (SBS) copolymers. The cross-linking of this photosensitive copolymer was investigated by analyzing the mechanical and morphological changes of each phase induced by the UV exposure. Main result is that the adhesive properties are strongly influenced by the cross-linking of the polybutadiene (PB) phase leading to an increase in the surface stiffness without affecting the surface energy. AFM analysis shows that th…