Antibacterial effects and tensile bonding strength of orthodontic adhesive containing nanohydroxyapatite

To evaluate the tensile bonding strength (TBS) and antibacterial properties when an orthodontic adhesive was added with nanohydroxyapatite (nHAp).

Light cure orthodontic adhesive (Grengloo) was blended with 2% TiO₂ containing nHAp nanoparticles by 0%、10%、20%、30% (w/w), while the control was not blended with nHAp. Brackets were bonded to extracted premolars by these new adhesives. TBS of 5groups were determined, and the adhesive remnant index (ARI) scores were assessed. Composite discs specimen were prepared, incubated with bacterial suspension for 48 h, and tested for antibacterial properties.

No significant difference was found in ARI. The colony unit counts and lactate productionof the groups containing 2% TiO₂ were significantly reduced. The colony unit counts and lactate production were without relationship with nHAp. The tensile bonding strength drastically decreased when containing more than 10% nHAp.

nHAp might not enhance the antibacterial effects of Grengloo.