Evaluation of the effects of high power led on shear bond strength of metal brackets as in vitro

n different intensity modes and duration. Materials-Methods: In this study, 75 extracted premolars which was extracted for orthodontic reasons in the Surgery Department of Dentistry Faculty of Ege University in 2017-2018 were divided into 3 groups (n=25). The teeth were embedded in acrylic blocks prepared in standard form, with the buccal surfaces exposed, and the specimens were divided into three groups having metallic brackets that were bonded using Transbond XT (3M-Unitek) and cured for 6 seconds-standard mode (1000 mW/cm2) (Group 1) or 8 seconds-high power mode (1400 mW/cm2) (Group 2) or 20 seconds-extra power mode (3200 mW/cm2) (Group 3) using "high power" LED curing light (OrthoValo, Ultradent). Then, the samples were stored in distilled water for 24 hours at 37°C, thermocycled and then debonded using an Universal Testing Machine (Shimadzu Autograph, AGS-J 5 kN, Shimadzu Corporation, Tokyo, Japonya). Bond failure was evaluated under stereomicroscopy (X16 magnification) using the adhesive remnant index (ARI). One-way analysis of variance (One way ANOVA) was performed to determine whether there was a significant difference in shear bond strengths between the groups. The Bonferonni test was used to determine which group was different when there was a significant difference in bonding strength between the groups. Results: As a result of the statistical evaluation between the groups, there was a significant difference in the bonding strength between group 1 (14.06±1.73) and group 2 (19.07±2.54), and group 1 (14.06±1.73) and group 3 (18.01±3.10). There was no statistically significant difference between group 2(19.07±2.54) and group 3 (18.01±3.10) (p<0.001). There was no significant difference between groups in terms of ARI scores (p>0.05). The highest score among the groups was 1 (45.3%). Conclusions: Similar effects were observed on the bond strength of the brackets for three different intensity modes and duration of high power LED curing lights. Although the value of the bond strength achieved after 20 seconds at a density of 1000 mW / cm2 was found to be lower than the other groups, there is no clinically significant difference since the literature shows that the bond strength at 6 MPa and above is sufficient. As a result; it is believed that using high power LED light sources for 6 seconds in "Extra High Power Mode" enables effective polymerization in a shorter time and saves work power and time because of decrease in the amount of labor spent at the patient.