Effect of Activation Mode on Shear Bond Strength of Metallic Brackets

Abstract

The aim of this study was to evaluate the shear bond strength (SBS) of metallic orthodontic brackets bonded to bovine teeth using light-activated or chemically activated composite resins. One hundred and twenty bovine mandibular incisors were divided into 6 groups (n=20), according to the bonding materials: Transbond XT (T); Enforce Dual (ED); Enforce chemical (EC); Enforce Light-activated (EL); Concise Orthodontic (C); and RelyX Unicem Capsule (UN). Metallic brackets were positioned and firmly bonded to the teeth. Lightactivation for T, ED, EL and UN was carried out with four exposures on each side of the bracket with 20 s total exposure times using XL2500 (3M ESPE). EC and C were chemically cured. Next, all specimens were stored in deionized water at 37 °C for 24 h. The shear bond strength was carried out at a crosshead speed of 1.0 mm/min. Data were subjected to one-way ANOVA and Tukey's test (α=0.05). The adhesive remnant index (ARI) was evaluated at 8× magnification. C (17.72±4.45) presented significantly higher SBS means (in MPa) than the other groups (p<0.05), followed by EC (11.97±5.77) and ED (10.57±1.32). EL (5.39±1.06) and UN (4.32±1.98) showed the lowest SBS means, while T (9.09±2.56) showed intermediate values. For ARI, there was a predominance of score 0 for EC, C and UN, and score 3 for T, ED and EL. In conclusion, the activation mode influenced the SBS.

Shear Bond Strength of Metallic Brackets: An In Vitro Stud

“…As for the shear strength, significant differences were observed among groups, corroborating several studies published in literature [4,[9][10][11]; and disagreeing from other studies [3,8].…”

“…Over the years, since the study carried out in 1965 [2], which idealized the bonding of brackets on the buccal surfaces of permanent teeth, numerous authors have studied ways of The bonding material selected for fixing brackets (Transbond® XT) is frequently used in orthodontic bonding procedures, which is a brand already established in the dental market and in several studies in literature [3,4,6,[8][9][10][11]. Conventional metallic orthodontic brackets were chosen because they are widely used in laboratory tests [3][4][5][6] and therefore widely used in orthodontic practice compared to national self-bonded and conventional imported materials.…”

“…After detachment, the buccal surfaces of teeth were analyzed through stereomicroscopic magnifying glass with magnification of 40 times to detect the amount of remaining adhesive and classified according to the Adhesive Remnant Index (ARI) [8][9][10][11][12][13], proposed in 1986 [14], with scores from 0 to 3: Score 0 = no remaining adhesive; Score 1 = less than 50% of the remaining adhesive; Score 2 = more than 50% of the remaining adhesive; Score 3 = 100% of the adhesive on the tooth.…”

“…Several studies in literature have analyzed shear tests with metallic and ceramic brackets [9], with recycled brackets [5], with etch self-adhesive systems [10], with metal brackets fixed with composite photo and chemically activated resins [11] and different cleaning methods for orthodontic bracket bases [8]. Based on the above, the aim of this study was to evaluate in vitro the shear strength of metallic brackets.…”

Effect of Composite Containing an Iodonium Salt on the Bond Strength of Brackets to Bovine Enamel

“…Metallic brackets are routinely bonded to the teeth using light-cured composite resins (1)(2)(3). The advantage of photoactivated composites is that the clinician has the control of working time to place the brackets in the correct position, easy removal of the excess composite and possibility of immediate insertion of the orthodontic archwire (4).…”