Shear bond strength and adhesive remnant index evaluation of three different orthodontic adhesive systems using three different light curing times

Background Success of long orthodontic treatment using orthodontic brackets depends mainly on the efficiency of the adhesive system used and it`s degree of resistance in the face of stresses and foresees applied during treatment. The aim of this study was to evaluate the shear bond strength of orthodontic brackets bonded with three adhesive systems using different light curing times. Materials and methods The 126 human extracted premolars were randomly divided into three equal groups (n = 42) depending on the type of adhesive system used; total-etch (Transbond XT), self-etch (Transbond Plus), and self-adhesive (GC-Ortho Connect) system. Then each group was randomly subdivided into three subgroups (n = 14) based on the curing time; 1-s, 3-s, and 20-s. The shear bond strength (SBS) and adhesive remnant index (ARI) were evaluated in each subgroup using universal testing machine and stereomicroscope respectively. The data were analyzed statistically by a two-way ANOVA for SBS, and Scheirer Ray Hare Test for ARI. The significance level was set at P ≤ 0.05. Results The results showed a statistically significant difference in shear bond strength at the three-time points for each adhesive system (p < 0.001) with the highest SBS value in 20-sec groups followed by 3-sec groups while 1-sec groups was the lowest. However, there was no statistically significant difference in Shear bond strength between the three adhesive systems except 20-sec groups (p < 0.001). ARI showed a statistically significant difference between all adhesive systems with the highest scores in TE groups, while the lowest in SE groups. Conclusion All adhesive systems provided acceptable values of SBS at all curing times except the 1-sec group in SE and SA adhesive systems where the SBS values were the lowest and below the acceptable range.