Shear bond strength of orthodontic brackets to porcelain surface using universal adhesive compared to conventional method

Soodeh Tahmasbi, Amin Shiri, Mohammadreza Badiee


Background: Considering the increase in demand for orthodontic treatment in adults, bracket bond
to restored teeth is a clinical challenge. This study sought to compare the shear bond strength (SBS)
of orthodontic brackets to feldspathic porcelain using universal adhesive and conventional adhesive
with and without silane application.
Materials and Methods: In this in vitro study Fifty‑six feldspathic porcelain discs were roughened
by bur, and 9.6% hydrofluoric acid was used for surface preparation. Samples were divided into
the following four groups (n = 14): Group 1: universal adhesive, Group 2: universal adhesive/silane,
Group 3: conventional adhesive, and Group 4: conventional adhesive/silane. Mandibular central
incisor brackets were bonded, and SBS was measured by Instron® machine. To assess the mode of
failure, adhesive remnant index (ARI) score was determined. The data were analyzed using SPSS
software and two‑way ANOVA, Bonferroni test, and Kruskal–Wallis test (P < 0.05 considered
Results: The highest SBS was noted in the universal adhesive/silane group (12.7 MP) followed
by conventional adhesive/silane (11.9 MP), conventional adhesive without silane (7.6 MP), and
universal adhesive without silane (4.4 MP). In the absence of silane, the conventional adhesive
yielded significantly higher SBS than universal adhesive (P = 0.03). In the presence of silane, the
two adhesives showed SBS values significantly higher than the values obtained when silane was not
applied, while the two adhesives were not significantly different in terms of SBS in the presence
of silane (P = 0.53). Based on ARI score, there were statistically significant differences between
Groups 1 and 4 (P = 0.00) and Groups 2 and 4 (P = 0.023).
Conclusion: Based on the current results, SBS of bracket to porcelain mainly depends on the use of
silane rather than the type of adhesive. Both universal and conventional adhesives yield significantly
higher SBS in the presence of silane compared to that in the absence of silane.


Orthodontic bracket, porcelain, shear bond strength, universal adhesive

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