<abstract xmlns="http://www.w3.org/1999/xhtml">

<sec>
<h3>Aim</h3>
<p>To compare the initial and fatigue shear bond strengths of a chromatic adhesive with a light-cured adhesive in an ex vivo laboratory study.</p>
</sec>
<sec>
<h3>Methods</h3>
<p>Hydroxyapatite discs were used as the bonding substrate. They were produced by cold uni-axial compression at 20 tons, sintered at 1300 °C and embedded in epoxy resin before grinding and polishing. One hundred and fifty upper left central incisor brackets were bonded to the discs with Transbond PLUS Color Change (3M Unitek, Monrovia, CA, USA) while another 150 similar brackets were bonded with Transbond XT (3M Unitek, Monrovia, CA, USA). Seventy-five brackets from each group were subjected to cyclic loading (5000 cycles at 2 Hz) at 50 per cent of the mean bond strength in a Dartec Series HC10 Testing Machine. Initial (unfatigued) and fatigued bond strengths were determined by applying a shear force at the bracket-substrate interface using a custom-made metal jig in an Instron Universal Testing Machine. One-way ANOVA with Bonferroni post-hoc correction and two-way ANOVA were used to analyse the differences between the initial and fatigue mean shear bond strengths of the adhesives. The survival and bond reliability of both adhesives were evaluated with the Kaplan-Meier and Cox regression analyses.</p>
</sec>
<sec>
<h3>Results</h3>
<p>The initial mean shear bond strength for Transbond PLUS Color Change (16.72 MPa) was higher than Transbond XT (15.11 MPa), but this was not statistically significant (<italic>p</italic> = 0.109). The fatigue mean shear bond strength for Transbond XT (15.87 MPa) was similar to that of Transbond PLUS Color Change (15.33 MPa), and the difference was not statistically significant (<italic>p</italic> > 0.999). There were no significant differences when the effects of the material (<italic>p</italic> = 0.264) or fatiguing (<italic>p</italic> = 0.512) were considered separately, but in combination, the effect on bond strength was statistically significant (<italic>p</italic> = 0.026). The survival analysis showed that both adhesives demonstrated similar survival patterns in the unfatigued and fatigued states. Analysis of the material type and fatiguing showed no effect on the survival pattern for both adhesives (<italic>p</italic> = 0.098).</p>
</sec>
<sec>
<h3>Conclusions</h3>
<p>There were no statistically significant differences between the mean initial (unfatigued) and fatigue bond strengths of Transbond XT and Transbond PLUS Color Change under laboratory conditions. A survival analysis for both resins with and without fatigue loading exhibited similar behaviour with respect to their survival patterns. Although this may imply that under clinical conditions the two adhesives could behave similarly, the clinical extrapolation of these results should be interpreted with caution.</p>
</sec>
</abstract>

Aim
To compare the initial and fatigue shear bond strengths of a chromatic adhesive with a light-cured adhesive in an ex vivo laboratory study.


Methods
Hydroxyapatite discs were used as the bonding substrate. They were produced by cold uni-axial compression at 20 tons, sintered at 1300 °C and embedded in epoxy resin before grinding and polishing. One hundred and fifty upper left central incisor brackets were bonded to the discs with Transbond PLUS Color Change (3M Unitek, Monrovia, CA, USA) while another 150 similar brackets were bonded with Transbond XT (3M Unitek, Monrovia, CA, USA). Seventy-five brackets from each group were subjected to cyclic loading (5000 cycles at 2 Hz) at 50 per cent of the mean bond strength in a Dartec Series HC10 Testing Machine. Initial (unfatigued) and fatigued bond strengths were determined by applying a shear force at the bracket-substrate interface using a custom-made metal jig in an Instron Universal Testing Machine. One-way ANOVA with Bonferroni post-hoc correction and two-way ANOVA were used to analyse the differences between the initial and fatigue mean shear bond strengths of the adhesives. The survival and bond reliability of both adhesives were evaluated with the Kaplan-Meier and Cox regression analyses.


Results
The initial mean shear bond strength for Transbond PLUS Color Change (16.72 MPa) was higher than Transbond XT (15.11 MPa), but this was not statistically significant (p = 0.109). The fatigue mean shear bond strength for Transbond XT (15.87 MPa) was similar to that of Transbond PLUS Color Change (15.33 MPa), and the difference was not statistically significant (p > 0.999). There were no significant differences when the effects of the material (p = 0.264) or fatiguing (p = 0.512) were considered separately, but in combination, the effect on bond strength was statistically significant (p = 0.026). The survival analysis showed that both adhesives demonstrated similar survival patterns in the unfatigued and fatigued states. Analysis of the material type and fatiguing showed no effect on the survival pattern for both adhesives (p = 0.098).


Conclusions
There were no statistically significant differences between the mean initial (unfatigued) and fatigue bond strengths of Transbond XT and Transbond PLUS Color Change under laboratory conditions. A survival analysis for both resins with and without fatigue loading exhibited similar behaviour with respect to their survival patterns. Although this may imply that under clinical conditions the two adhesives could behave similarly, the clinical extrapolation of these results should be interpreted with caution.

Initial and fatigue bond strengths of chromatic and light-cured adhesives

Australasian Orthodontic Journal

This work is licensed under the Creative Commons Attribution 4.0 International License.

{"article-title":"Initial and fatigue bond strengths of chromatic and light-cured adhesives"}

Aim
To compare the initial and fatigue shear bond strengths of a chromatic adhesive with a light-cured adhesive in an ex vivo laboratory...

Initial and fatigue bond strengths of chromatic and light-cured adhesives

Published Online: Dec 14, 2023

Page range: 119 - 126

Received: Feb 01, 2010

Accepted: Mar 01, 2010

DOI: https://doi.org/10.2478/aoj-2010-0020

© 2010 June M.L. Lee et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.