Page 22 - SPEMD_62-1

Revista Portuguesa de Estomatologia,
Medicina Dentária e Cirurgia Maxilofacial

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

Original Research

Bond strength of orthodontic brackets
to polymethylmethacrylate: effect of the surface

treatment and adhesive system

Rita Matos Cardoso*, Joana Godinho, Luís Jardim

Department of Orthodontics, Faculdade de Medicina Dentária, Universidade de Lisboa, Lisbon, Portugal

a r t i c l e i n f o a b s t r a c t

Article history: Objectives: To evaluate the influence of the surface treatment and adhesive system on the
Received 19 September 2020 shear bond strength and the failure mode of orthodontic brackets bonded to polymethyl-
Accepted 24 December 2020 methacrylate surfaces.
Available online 29 January 2021 Methods: Ninety metal brackets (n=15) were bonded to aged discs of polymethylmeth-
acrylate SR Ivocron subjected to three surface conditions (no treatment; sandblasting with
Keywords: 50-μm aluminum oxide; roughening with a tungsten bur), using two combinations of ad-
Adhesion hesives (methylmethacrylate monomer + Transbond XT Primer; Scotchbond Universal Ad-
Adhesive remnant index hesive) followed by the composite Transbond XT. In the control group, metal brackets were
Adhesives bonded with Transbond XT to 15 human mandibular incisors. The specimens were ther-
Brackets mocycled, stored in distilled water (37ºC, 7 days), and tested in shear, using an Instron
Orthodontics universal machine. Failure mode was classified according to the adhesive remnant index
Polymethylmethacrylate using a stereomicroscope. The data were analyzed with an analysis of variance and post-
Shear strength hoc tests (p<0.05).
Surface treatment Results: Significant differences were found between the bracket bond strength to polyme-
thylmethacrylate with different surface treatments (p<0.001). Sandblasting with aluminum
oxide was superior to tungsten bur roughening. The adhesive system did not significantly
influence the shear bond strength nor the failure mode (p=0.8415). All experimental groups
showed lower bond strengths than the control group (p=0.1566).
Conclusions: Mechanical surface treatment significantly influenced the bracket’s bond
strength to polymethylmethacrylate. Sandblasting with aluminum oxide was the most ef-
fective mechanical treatment. The weakest adhesive link was found at the acrylic-adhesive
interface. Orthodontic bonding to polymethylmethacrylate was weaker than bonding to
enamel, regardless of the surface treatment and the adhesive used. (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/).

* Corresponding author.
E-mail address: rita.matoscardoso@gmail.com (Rita Matos Cardoso).
http://doi.org/10.24873/j.rpemd.2021.01.818
1646-2890/© 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/).