[Microshear bond strength of transbond XT and assure universal bonding resin to stainless steel brackets, amalgam and porcelain]

Assure universal bonding resin is marketed with fluoride releasing potential. The manufacturer claims that it provides adequate bond strength between the bracket and amalgam and porcelain. This study compared the shear bond strength of Transbond XT and Assure universal bonding resin to stainless steel brackets, amalgam and porcelain in vitro. In this vitro study, 20 standard brackets of the maxillary central incisors, 20 feldspathic porcelain specimens and 20 self-cure acrylic cavities filled with amalgam were divided into 2 groups bonded with Transbond XT, and Assure. After surface preparation in each group, Transbond XT composite was applied to the surfaces using silicon tubes and light-cured for 20 seconds. Then, the microshear bond strength was determined using Zwick Roell machine. The data were subjected to two-way ANOVA, Tukey's post hoc test, Student's t-test and the Kruskal Wallis test. Different microshear bond strengths were obtained for the bond to stainless steel brackets, amalgam and porcelain by Transbond XT and Assure resin [p<0.000]. Using Assure for bonding to amalgam [7.2 +/- 1.46 vs. 10.12 +/- 4.97] and brackets [16.14 +/- 3.2 vs. 20.16 +/- 5.12; p<0.05] decreased microshear bond strength. However, Assure significantly increased the bond strength to porcelain compared to Transbond XT [28.84 +/- 6.42 vs. 22.48 +/- 3.6; p<0.01]. Non-parametric Kruskal-Wallis test showed significant differences in adhesive remnant index [ARI] between the two bonding agents only in the amalgam group [p=0.029]. Although the bond strength values of Assure were less than those of Transbond XT, Assure was able to create sufficient bond strength especially to porcelain

[Effect of saliva contamination on shear bond strength of transbond XT and assure universal bonding resin to enamel]

Assure universal bonding resin is a modified cement with fluoride releasing property. It is claimed to provide adequate bond strength between the bracket and enamel in wet conditions; although more studies are required in this regard. This study compared the shear bond strength of Transbond XT and Assure universal bonding resin to dry and saliva-contaminated enamel in vitro. In this in vitro study, 60 extracted human premolars were selected and stainless steel brackets were bonded to enamel surfaces. Bonding of brackets to enamel surfaces was done using Assure universal bonding resin [dry condition], Transbond XT [dry condition] and Assure [saliva-contaminated condition]. The shear bond strength of brackets to the enamel was determined by Zwick/Roell machine in three groups. Data were analyzed using one-way analysis of variance [ANOVA], and the Kruskal Wallis test. The mean shear bond strength of brackets to enamel surfaces bonded with Assure [dry condition], Transbond XT and Assure [saliva-contaminated condition] was 14.18 +/- 4.78 MPa, 16.13 +/- 5.49 MPa and 13.32 +/- 4.74 MPa, respectively [with no significant differences]. Non-parametric Kruskal-Wallis test found no significant differences regarding the adhesive remnant index [ARI]. [P=0.053]. Bonding of stainless steel brackets to enamel surfaces with Assure universal bonding resin provided adequate bond strength in dry and saliva-contaminated conditions. Thus, it may be used for bonding of orthodontic brackets to the enamel surfaces in the clinical setting