Delivery of antibacterial nanoparticles into dentinal tubules using high-intensity focused ultrasound.
BACKGROUND
High-intensity focused ultrasound (HIFU) produces collapsing cavitation bubbles. This study aims to investigate the efficacy of collapsing cavitation bubbles to deliver antibacterial nanoparticles into dentinal tubules to improve root canal disinfection.


METHODS
In stage 1, experiments were performed to characterize the efficacy of collapsing cavitation bubbles to deliver the miniature plaster beads into a tubular channel model. In stage 2, experiments were conducted on root-dentin blocks to test the efficacy of HIFU applied at 27 kHz for 2 minutes to deliver antibacterial nanoparticles into dentinal tubules. After the stage 2 experiment, the samples were sectioned and analyzed using field-emission scanning electron microscopy and energy dispersive X-ray analysis.


RESULTS
The stage 1 experiment showed that collapsing cavitation bubbles using HIFU delivered plaster beads along the entire length of the tubular channel. It was observed from the stage 2 experiments that the diffusion of fluids alone was not able to deliver antibacterial nanoparticles into dentinal tubules. The collapsing cavitation bubbles treatment using HIFU resulted in significant penetration up to 1,000 microm of antibacterial nanoparticles into the dentinal tubules. The statistical analysis showed a highly significant difference in the depth of penetration of antibacterial nanoparticles between the two groups (<0.005).


CONCLUSIONS
The cavitation bubbles produced using HIFU can be used as a potential method to deliver antibacterial nanoparticles into the dentinal tubules to enhance root canal disinfection.
Shrestha
Annie
A
Department of Restorative Dentistry, National University of Singapore, Singapore.
Fong
Siew-Wan
SW
Khoo
Boo-Cheong
BC
Kishen
Anil
A
D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000382:microbiology; D003804:Dentin / Q000382:microbiology / Q000648:ultrastructure*; D016503:Drug Delivery Systems; D006801:Humans; D045423:Microbubbles; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles; D014465:Ultrasonics
D000900:Anti-Bacterial Agents