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rev port estomatol med dent cir maxilofac . 2021;62(1):16-22 17

Adesão de brackets ortodônticos a polimetilmetacrilato:
Efeito do tratamento de superfície e do sistema adesivo

r e s u m o

Palavras-chave: Objetivos: Avaliar a influência do tratamento de superfície e de sistemas adesivos na resis-
Adesão tência adesiva e tipo de falha de brackets metálicos cimentados a superfícies de polimetil-
Índice de adesivo residual metacrilato.
Adesivos Métodos: 90 brackets metálicos (n=15) foram cimentados a discos de polimetilmetacrilato SR
Brackets Ivocron envelhecidos, usando 3 condições de superfície (sem tratamento; jato de óxido de
Ortodontia alumínio de 50 μm; broca de tungsténio), utilizando 2 combinações de adesivos (monómero
Polimetilmetacrilato de metilmetacrilato + Transbond XT Primer; Scotchbond Universal Adhesive) seguido do
Resistência ao cisalhamento compósito Transbond XT. Brackets cimentados a 15 incisivos mandibulares humanos com
Tratamento de superfície Transbond XT foram usados como controlo. A resistência adesiva ao cisalhamento foi ava-
liada com Instron, após termociclagem e armazenamento em água destilada (37ºC, 7 dias).
O tipo de falha foi classificado pelo índice de adesivo residual, utilizando um estereomicros-
cópio. Os dados foram analisados com uma análise de variância e testes post-hoc (p<0,05).
Resultados: Verificaram-se diferenças significativas na adesão ao polimetilmetacrilato entre
os tratamentos da superfície (p<0,001), sendo o jateamento com óxido de alumínio superior
à abrasão com broca de tungsténio. O sistema adesivo não influenciou significativamente
a resistência adesiva nem o tipo de falha (p=0,8415). Os grupos experimentais obtiveram
valores de adesão inferiores aos do controlo (p=0,1566).
Conclusões: O tratamento mecânico da superfície influenciou significativamente a adesão
de brackets ao polimetilmetacrilato. O jato de óxido de alumínio foi o tratamento mecânico
mais eficaz. A união acrílico-adesivo foi o elo mais fraco da interface adesiva. A adesão ao
polimetilmetacrilato foi inferior à adesão ao esmalte, independentemente do tratamento
de superfície e do adesivo. (Rev Port Estomatol Med Dent Cir Maxilofac. 2021;62(1):16-22)
© 2021 Sociedade Portuguesa de Estomatologia e Medicina Dentária.
Published by SPEMD. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).

with adverse consequences on the cost and efficiency of or-
Introduction 2
thodontic treatment and patient comfort. Brackets’ bond
The evolution of orthodontic techniques over the last decades strength to restorative materials should be strong enough to
has led to a significant increase in the number of adults seek- withstand the orthodontic forces but weak enough to allow for
ing treatment. These patients often have restored teeth, and, debonding without damaging the tooth surface. 14
in many cases, orthodontic procedures are performed concur- New universal adhesive systems aimed to improve the ex-
rently with other dental treatments. The presence of surfac- isting ones have been introduced in the market over the last
1,2
es restored with different materials makes it difficult to bond decade. These adhesives are advertised as being effective for
orthodontic brackets, which has motivated studies on adhe- adhesion to various substrates due to various associated
sion to gold, amalgam, composite and ceramic surfaces. 3 -8 chemicals in their composition. 15-18 This versatility can be use-
In multidisciplinary treatments involving prosthodontics ful in bonding orthodontic brackets to PMMA crowns.
and orthodontics, the need for bonding brackets to temporary Although there are studies in the literature evaluating the
9
crowns arises to avoid damage to the final restoration. The influence of surface treatment on brackets’ adhesion to pro-
materials used for manufacturing temporary crowns can be visional crowns, 2,9,14,19-21 no published research testing the
divided according to their chemical composition into two new universal adhesives or the application of the methyl-
groups: methacrylate acrylic resins (polymethyl, polyethyl, methacrylate monomer (MMA) combined with mechanical
and polyvinyl methacrylates) and Bis -acryl and Bis -GMA surface treatment was found. Therefore, the main objective
composite resins. 10,11 However, in more complex cases, name- of the present investigation was to evaluate the influence of
ly multiple or long -term provisional restorations, polymeth- surface treatment and two adhesive systems on the bond
ylmethacrylate (PMMA) acrylic resins remain the materials strength of metal brackets to PMMA surfaces, according to
of choice. 12,13 the following null hypotheses (H0): the adhesion of brackets
Previous studies have shown that brackets’ bond strength to the PMMA surface is not significantly influenced by the
to PMMA surfaces is lower than the clinically acceptable val- adhesive system or the surface treatment. A secondary ob-
ues. 2,14 In orthodontic practice, a weak adhesion of brackets to jective was to identify the types of bonding failure by com-
temporary materials leads to a high rate of adhesive failures, paring these different adhesive systems and surface treat-