Effect of Reducing Curing Time on the Shear Bond Strength of Metal Orthodontic Brackets: An In Vitro Comparative Study

Background The aim of this study was to evaluate the effect of different curing time of LED light cure on the shear bond strength of stainless steel orthodontic brackets bonded to human teeth in comparison with light exposure of 40 seconds from a conventional halogen-based light-curing unit which was used as a control. Materials and Methods Thirty sound maxillary premolar teeth extracted from patients seeking orthodontic treatment were selected for this study. These teeth were divided into three equal groups. In the first group, the brackets were bonded using Halogen light cure for 40 seconds. In the second group, the brackets were bonded using Woodpecker i-Led light cure for 3 seconds, while in the third group, the brackets were bonded using Woodpecker i-Led light cure for one second. The samples were evaluated for bond strength using an Instron universal testing machine 24 hours after bonding procedure, while for adhesive remnant index, the enamel surface and bracket base of each tooth were examined under magnifying lens (20X) of a stereomicroscope. One way ANOVA and Tukey's tests were used to compare the shear bond strength among the groups, while Pearson's chi-square was used to assess the adhesive remnant index. Results The shear bond strengths of both groups of LED unit were higher than halogen one, with a statistically high significant difference. Score 2 and 3 were the predominant scores for the adhesive remnant index, with a non-significant difference among tested groups. Conclusions Both of the LED unit's groups showed clinically acceptable shear bond strength in comparison to halogen, so the time of bonding reduced without jeopardizing the shear bond strength or enamel damage after debonding.