Shear bond strength of orthodontic color-change adhesives with different light-curing times

Abstract

Background: The purpose of this study was to evaluate the effect of light-curing time on the
shear bond strength (SBS) of two orthodontic color-change adhesives (CCAs).
Materials and Methods: A total of 72 extracted premolars were randomly assigned into 6 groups
of 12 teeth each. Subsequent to primer application, a metal bracket was bonded to the buccal surface
using an orthodontic adhesive. Two CCAs (Greengloo and Transbond Plus) were tested and one
conventional light-cured adhesive (Resilience) served as control. For each adhesive, the specimens
were light-cured for two different times of 20 and 40 s. All the specimens underwent mechanical
testing using a universal testing machine to measure the SBS. Adhesive remnant index (ARI) was
used to assess the remnant adhesive material on the tooth surface. All statistical analyses were
performed using SPSS software. The signifi cance level for all statistical tests was set at P ≤ 0.05.
Results: The SBSs of the tested groups were in the range of 14.05-31.25 MPa. Greengloo adhesive
showed the highest SBS values when light-cured for 40 s, and Transbond Plus adhesive showed the
lowest values when light-cured for 20 s. ARI scores of Transbond Plus adhesive were signifi cantly
higher than those of controls, while other differences in ARI values were not signifi cant.
Conclusion: Within the limitations of his study, decreasing the light-curing time from 40 to 20 s
decreased the SBS of the tested adhesives; however, this decline in SBS was statistically signifi cant
only in Transbond Plus adhesive
Key Words: Adhesive system, bond strength, dental adhesive, light curing, orthodontic
bonding, shear bond strength