Shear Bond Strength of Metallic Brackets: An In Vitro Stud

Abstract

Objective: To evaluate in vitro the shear bond strength of metallic brackets. Material and Methods: Forty premolars were divided into four groups (n = 10) according to the type of brackets used (G1: Morelli® Light; G2: Morelli® Standard; G3: Morelli® Max; G4: Abzil® Agile). For bonding, Transbond XT® (3M Unitek) resin was used in all groups. Teeth were embedded in ¾ inch PVC tubes with special plaster stone, perpendicular to the ground. Brackets were fixed on the geometric centers of the exposed crowns. After bonding, teeth were stored in distilled water, incubated at 37ºC for 24 hours and submitted to 500 thermal cycles for 30 seconds in each bath (5°C and 55°C), respectively. The bond strength test was performed on the Instron® mechanical testing machine with 3kg load cell at speed of 0.5mm/min. Data were submitted to statistical analysis through the Statistica® software, version 5.0, by Kruscal Wallis test, ANOVA and Tukey (p< 0.05). Results: There was no statistically significant difference in the ARI scores; whereas for shear resistance, this difference was significant (Averages: G1 -Light: 17.53MPa; G2 -Standard: 18.11MPa; G3 -Max: 29.33MPa; G4 -Agile: 11.37MPa) and G3 showed better performance, compared to the others. All other groups showed similar behavior among themselves. Conclusion: Max bracket had the highest shear strength. Further studies should be conducted to investigate the meshes of brackets tested in this study.

Physical and chemical mechanisms involved in adhesion of orthodontic bonding composites: in vitro evaluations

“…According to S. Elekdag-Turk, the prevalence of adhesive bond failure at the bracket/resin interface becomes a protective phenomenon for the enamel, precisely because, at the moment of detachment, this structure remains intact, preventing damage such as the loss of superficial tissue fragments therefore, cleaning the dental surface from the residual adhesive resin is perhaps less risky than the damage induced by bracket debonding [ 50 ]. Regarding the breaking of the bond at the enamel/adhesive interface, according to T. De Melo, the anatomy, the curvature and the design of the base of the bracket, may be the factors responsible for the greater strength of the bonding at bracket/adhesive interface and is just this condition to favour the major preservation of the dental enamel, because only a thin layer of residual material remains to be removed by milling [ 51 ].…”

Influence of Polymerization with Argon Laser and LED on Shear Resistance of Adhesive Systems

“…After cleaning, they were stored in distilled water, under refrigeration, until the moment of the shear test. The distilled water was changed fortnightly [1,2].…”

“…The sample consisted of 28 maxillary premolars, whose buccal surfaces were evaluated with a stereomicroscopic magnifying glass (Model SMZ 745, Nikon ® ), 40x magnification [1,2,20], to attest its integrity. The teeth were randomly divided into two large groups of 14 specimens each, according to the adhesive system used.…”

“…Achieving an effective union of dental materials to dental structures is a goal pursued for a long time in Dentistry. Adhesion is a surface bonding process, determined by the specific intermolecular attraction between the material and the substrate, through chemical and/or physical reactions [1,2] Detachment of orthodontic accessories is a routine problem in the orthodontic clinic and results in delays in care and an increase in the cost of maintenance of fixed appliances [1][2][3]. The success of direct bonding in orthodontics began with Newman [4]., through a study that established the bonding of brackets to the buccal surface of teeth.…”

“…The efficient polymerization of adhesive materials, decreasing the polymerization shrinkage process, is of paramount importance for the strength and durability of the substrate/fixer adhesion, directly influencing the shear strength. Thus, the bonding of orthodontic accessories can resist the efforts imposed by the dynamics of the stomatognathic system, reflecting clinical benefits for patients and professionals [1].…”