Evaluation of an alternative technique to optimize direct bonding of orthodontic brackets to temporary crowns

Abstract

OBJECTIVE: To compare shear bond strength of different direct bonding techniques of orthodontic brackets to acrylic resin surfaces. METHODS: The sample comprised 64 discs of chemically activated acrylic resin (CAAR) randomly divided into four groups: discs in group 1 were bonded by means of light-cured composite resin (conventional adhesive); discs in group 2 had surfaces roughened with a diamond bur followed by conventional direct bonding by means of light-cured composite resin; discs in group 3 were bonded by means of CAAR (alternative adhesive); and discs in group 4 had surfaces roughened with a diamond bur followed by direct bonding by means of CAAR. Shear bond strength values were determined after 24 hours by means of a universal testing machine at a speed of 0.5 mm/min, and compared by analysis of variance followed by post-hoc Tukey test. Adhesive remnant index (ARI) was measured and compared among groups by means of Kruskal-Wallis and Dunn tests. RESULTS: Groups 3 and 4 had significantly greater shear bond strength values in comparison to groups 1 and 2. Groups 3 and 4 yielded similar results. Group 2 showed better results when compared to group 1. In ARI analyses, groups 1 and 2 predominantly exhibited a score equal to 0, whereas groups 3 and 4 predominantly exhibited a score equal to 3. CONCLUSIONS: Direct bonding of brackets to acrylic resin surfaces using CAAR yielded better results than light-cured composite resin. Surface preparation with diamond bur only increased shear bond strength in group 2.

Adhesion strength of orthodontic brackets to acrylic surfaces. A systematic review on in vitro studies.

“…Four studies evaluated three different surface treatments, 2,5,7,9 two evaluated two pre-treatments 10,11 and one analysed 14 groups all with different substrate treatments. 12 The surface treatments applied were the following: none (control), 5,12 polished with greenstone, 5 sandblasted, 2,5,7,9,11,12 silane, 12 diamond bur, 10,11,12 9.6% hydrofluoric acid, 12 37% phosphoric acid, 7,12 monomer, 2,12 plastic conditioner, 12 silica carbide paper, 2,9 pumice polishing paste, 2 pumice and rubber cup 10 and Laser Er:YAG. 7 Sandblasting with 50-μm Al 2 O 3 particles was performed in test groups of six studies.…”

“…12 Another study also indicated that bond strength was influenced by the surface treatment but only for the light-cure composite resin. 10 Type of adhesive (n=5). Three articles reported a comparison between the use of an acrylic resin and a light-cure composite resin and between a bond metal bracket and an acrylic surface.…”

“…Three articles reported a comparison between the use of an acrylic resin and a light-cure composite resin and between a bond metal bracket and an acrylic surface. 2,10,13 One article compared a composite resin with a cyanoacrylate adhesive and Panavia TM used in different protocols. 11 Another study evaluated the adhesion of a resin-reinforced glass ionomer to metal and ceramic brackets and of a composite resin to acrylic substrates.…”

“…4 Bond strength was reported after shear bond strength tests in MPa and was shown to be influenced by the type of adhesive in four articles. 2,10,11,13 Only one study showed no influence of the adhesives on bond strength. 4 Ageing samples protocols (n=3).…”

“…5 Other relevant variables -Adhesive remnant index (ARI) and failure mode. The adhesive remnant index, firstly described by Artun and Bergland (1984), 14 was used in five studies 2,5,8,9,10 to categorise the amount of adhesive remaining on the substrate 2,5,8,9 and/or determine the adhesion failure mode. 5,9 Three studies used the ARI only for categorisation.…”