Effect of different surface treatment with panaviaV5 on shear bond strength of metal brackets to silver amalgam

Abstract

Background: This study was conducted to compare the shear bond strength (SBS) of orthodontic
brackets to amalgam surfaces by two surface treatment methods, two different adhesives, and one
intermediate resin and also to evaluate surface roughness after two preparation methods as well
as bond failure mode.
Materials and Methods: In this in‑vitro study forty‑eight amalgam samples were randomly allocated
to four groups. In Groups 1–3, specimens were sandblasted with 50 μm aluminum oxide, followed
by application of Alloy primer in Groups 1 and 2. In Group 3 Alloy primer had not used. In Group 4,
samples were prepared by silica coating using a silane coupling agent. Surface roughness analysis
was performed in 10 additional samples after two surface treatments. The brackets in Group 1
were bonded with Transbond XT and those in other groups were bonded with Panavia V5. All
specimens were examined for SBS following 5000 times thermocycling at 5°C–50°C. Modified
adhesive remnant index was utilized for the bond failure mode. Data analysis was done by one‑way
analysis of variance, post hoc Tukey, Kruskal–Walli and Mann–Whitney U tests. Statistical significance
was set at P < 0.05.
Results: The findings indicated the mean SBS were low (ranged from 0.19 to 4.66 MPa) and
significantly lower in Group 3 than in Group 4 (P = 0.009). Bond failure occurred in adhesive/
amalgam interface in nearly all samples. Silica coating produced significantly lower roughness than
sandblast (P = 0.009).
Conclusion: Silica coating had a significant higher bond strength than sandblast without application
of Alloy primer. However compared to sandblast with Alloy primer, silica coating did not significantly
improve the bond strength. Chemical bond between PanaviaV5 and sandblasted amalgam was not
considerable.
Key Words: Dental amalgam, orthodontic brackets, Panavia, shear strength