1 Associate Professor of Orthodontics, Dental Caries Prevention Research Center, Qazin University of Medical Sciences, Qazvin, IR Iran

2 Assistant Professor, Orthodontic Department, Lorestan University of Medical Sciences, Khorramabad, IR Iran


Background: Assure Universal Bonding Resin is capable of providing a strong bond between orthodontic attachments and amalgam surfaces.
Objectives: This study sought to assess the shear bond strength of orthodontic attachments to amalgam surfaces using Assure Universal Bonding Resin after different surface treatments.
Methods: This in-vitro experimental study was conducted on 120 amalgam samples in eight groups of surface roughening with diamond bur, sandblasting with aluminum oxide particles, Er, Cr: YSGG laser irradiation and polishing-only. Molar buccal tubes were bonded to amalgam surfaces using Assure primer and Transbond Plus light-cure composite. Half the samples were immediately subjected to shear bond strength testing while the remaining half were incubated at 37°C for one week, thermocycled (1000 cycles) and were then subjected to shear bond strength test. One-way ANOVA was applied to compare the bond strength of the groups and Tukey’s test was used for pairwise comparisons. The adhesive remnant index (ARI; 4 point-scale) was also determined in the groups and the results were analyzed using the Kruskal-Wallis test.
Results: Significant differences were noted in shear bond strength of attachments following the application of Assure among different surface treatment modalities (P < 0.001); the highest bond strength was noted in sandblasted group followed by laser, bur and polishing, respectively. Aging had no significant effect on bond strength.
Conclusions: Sandblasting and irradiation of Er, Cr: YSGG laser provided sufficiently high bond strength between amalgam and attachments following the application of Assure. Diamond bur and polishing did not provide adequately high bond strength.