Effect of Adding Luteolin Nanoparticles on the Antibacterial and Mechanical Properties of an Orthodontic Adhesive

The current study aimed to evaluate the effect of adding Luteolin nanoparticles in two different concentrations (1% and 3%) on the mechanical and antibacterial properties of the Transbond XT Unitek Orthodontic Adhesive. Materials and Methods: Thirty extracted human upper premolar teeth were used for the shear bond strength test (SBS). The teeth were randomly divided into three groups, ten teeth each: Control group, Luteolin 1% and Luteolin 3% Nanoparticles (NPs) groups. The mesh of the brackets was covered with transbond or modified adhesives, which were then adhered to the teeth. The brackets were debonded using a universal testing machine, and the adhesive remnant index was checked using a stereomicroscope at a 10X magnification. Thirty composite discs were used for the antibacterial test. ten discs were made from transbond adhesive as a control group, and twenty discs (divided equally) were prepared from orthodontic adhesive modified by incorporating Luteolin 1% and Luteolin 3% nanoparticles. The adhesives antibacterial activity against Streptococcus mutans and Lactobacillus acidophilus was determined by the disk diffusion technique. Statistical analysis was done at P >0.05. Results: The Control group's shear bond strength was statistically higher than that of the other groups (16.1 MPa for the control group and 12.9 MPa, 10.8 MPa for luteolin 1% and Luteolin 3%, respectively). However, the SBS results of this study demonstrated that the mean of all groups was more than that recommended by Reynolds (5.9-7.8 MPa) in (1975). The disc diffusion method showed that 3% luteolin modified adhesive was more effective than luteolin 1% and the control groups, with a larger bacterial inhibition zone. Conclusions: The incorporation of Luteolin NPs in orthodontic resin produced an antibacterial effect againstStreptococcus mutans and Lactobacillus acidophilus without compromising the shear bond strength.