Abstract: Objective To evaluate the effect of titanium dioxide (TiO2) nanoparticles on tensile bonding strength (TBS) and antibacterial properties of an orthodontic adhesive. Methods Light cure orthodontic adhesive (Grengloo) was blended with TiO2 nanoparticles by 1%, 2%, 3% (mass fraction). The control was not blended with TiO2. Brackets were bonded to extracted premolars by these new adhesives. TBS of four groups was determined, and the adhesive remnant index (ARI) scores were assessed. A total of 20 composite discs specimen were prepared, and incubated with bacterial suspension for 48 hours and tested for antibacterial properties. Results No significant difference was found among TBS and ARI of the four groups. PH values of group 2% and 3% were significantly increased and lactate production was significantly reduced compared with the control group, but no significant difference was found between these two groups. The colony unit counts of the three groups containing TiO2 were significantly reduced, but no significant difference among these three groups was observed. Conclusion Adding 2%TiO2 to Grengloo enhances its antibacterial effects without increasing the tensile bonding strength.

Key words: TiO2 nanoparticles, orthodontic adhesive, antibacterial, tensile bonding strength