Shear Bond Strength at the Resin/Bracket Interface of Sandblasted Brackets with Different Aluminum Oxide Particle Size

The purpose of this study was to evaluate in vitro the shear bond strength of recycled orthodontic brackets. S2C-03Z brackets (Dental Morelli, Brazil) were bonded to the buccal surfaces of 50 extracted human premolars using Concise Orthodontic chemically cured composite resin (3M, USA). The teeth were randomly assigned to 5 groups (n=10), as follows. In group I (control), the bonded brackets remained attached until shear testing (i.e., no debonding/rebonding). In groups II, III and IV, the bonded brackets were detached and rebonded after recycling by 90-mum particle aluminum oxide blasting, silicon carbide stone grinding or an industrial process at a specialized contractor company (Abzil-Lancer, Brazil), respectively. In group V, the bonded brackets were removed and new brackets were bonded to the enamel surface. Shear bond strength was tested in an Instron machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. There was no statistically significant difference (p>0.05) between the control brackets (0.52 kgf/mm²), brackets recycled by aluminum oxide blasting (0.34 kgf/mm²) and new brackets attached to previously bonded teeth (0.43 kgf/mm²). Brackets recycled by the specialized company (0.28 kgf/mm²) and those recycled by silicon carbide stone grinding (0.14 kgf/mm²) showed the lowest shear strength means and differed statistically from control brackets (0.52 kgf/mm²) (p<0.05). In conclusion, the outcomes of this study showed that bracket recycling using 90-µm aluminum oxide particle air-abrasion was efficient and technically simple, and might provide cost reduction for orthodontists and patients alike.

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Comparison of shear bond strength of brackets recycled using micro sandblasting and industrial methods

The Angle Orthodontist ◽

10.2319/032414-221.1 ◽

2014 ◽

Vol 85 (3) ◽

pp. 461-467 ◽

Cited By ~ 3

Author(s):

Manuela M. Haro Montero ◽

Ascensión Vicente ◽

Noelia Alfonso-Hernández ◽

Manuel Jiménez-López ◽

Luis-Alberto Bravo-González

Keyword(s):

Bond Strength ◽

Aluminum Oxide ◽

Shear Bond Strength ◽

Oxide Particle ◽

The Other ◽

Group 4 ◽

Group 3 ◽

Oxide Particles ◽

Group 2

ABSTRACT Objective: To evaluate in vitro the shear bond strength of brackets recycled by sandblasting with aluminum oxide particles of different sizes or reconditioned industrially after successive rebonding. Materials and Methods: Eighty brackets were bonded and debonded sequentially three times. After the first debonding, brackets were divided into four groups: (group 1) sandblasting with aluminum oxide particles of 25 μ, (group 2) 50 μ, and (group 3) 110 μ, and (group 4) industrial recycling. Bond strength and adhesive material remaining on debonded bracket bases were evaluated for each successive debond. Results: No significant differences were detected between the four groups following the first recycle (P > .05). After the second recycle, bond strength was significantly greater for the industrially recycled group than the other groups (P < .016). When shear bond strength was compared within each recycling method, the bond strength of sandblasted brackets decreased with the increase of particle size and with each recycle; for the industrially recycled group, no significant differences were detected between the three sequences (P > .016). In the evaluation of bond material remnant, the industrially recycled group left significantly less bond material after successive recycling than the other groups did (P < .016). Within each recycling method, the adhesive remnant decreased significantly after successive debond (P < .016). Conclusions: Industrial recycling obtained better results than sandblasting after three successive debondings. The brackets' shear bond strength decreased as the size of the aluminum oxide particle used for sandblasting increased and as recycling was repeated.

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