Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 19 0 2022 01 25 3591 3591 Nastaran Sharifi Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Zahra Mohammadi Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Sepideh Arab Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Maryam Shojaee Department of Restorative Dentistry, Qazvin University of Medical Sciences, Qazvin, Iran Fatemeh Vafadoost School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Azadeh Zakerzadeh Dental Caries Prevention Research Center, Qazvin University of Medical Sciences, Qazvin, Iran 2020 05 15 2021 01 02 Objectives: The purpose of this study was to evaluate the effect of saliva contamination on shear bond strength (SBS) of orthodontic brackets bonded by a self-adhering composite compared with a conventional adhesive. Materials and Methods: This in vitro, experimental study investigated 40 human premolars. The teeth were randomly divided into four groups based on the adhesive type and bonding condition: (I) Vertise Flow composite without saliva contamination (VF), (II) Vertise Flow composite with saliva contamination (VF/S), (III) Transbond XT composite without saliva contamination (TXT), and (IV) Transbond XT composite with saliva contamination (TXT/S). After the preparation step, brackets were bonded to the buccal surface of the teeth, and samples were mounted in acrylic blocks, incubated at 37°C for 24 hours, and underwent thermocycling between 5- 55°C. Next, the SBS was measured by a universal testing machine. Data were analyzed by ANOVA and Tukey’s test.  P<0.05 was considered statistically significant. Results: ANOVA showed a significant difference in SBS among the groups (P<0.001). The highest SBS was achieved in the TXT group (26.63±9.09 MPa), followed by TXT/S (13.69±4.23 MPa), VF/S (3.68±1.49 MPa), and VF (3.04±1.73 MPa). Conclusion: Saliva contamination did not have a significant effect on SBS of brackets bonded with Vertise Flow. However, it did not provide acceptable bond strength for orthodontic bracket bonding in the clinical setting. https://fid.tums.ac.ir/index.php/fid/article/view/3591