Thousands of times smaller than the width of a human hair, they have been widely explored for use in dentistry, cancer therapy, imaging and regenerative medicine, among other applications.
During a root canal, inflamed dental pulp is removed and the empty space is then filled in with a polymer called gutta percha, which is used in part because it does not react within the body.
But some root canals don`t entirely remove the infection, and residual infection after root canals can lead to tooth loss.
In addition, traditional gutta percha has certain shortcomings, including a limited capacity to ward off infection and less-than-optimal rigidity.
To overcome those issues, researchers from the University of California, Los Angeles School of Dentistry developed and tested two types of reinforced gutta percha - one strengthened with nanodiamonds and another strengthened with nanodiamonds that had been pre-loaded with antibiotics.
To evaluate the first type, Sue Vin Kim and Adelheid Nerisa Limansubroto, study co-authors who are UCLA Dentistry students, filled actual teeth from human patients.
Using conventional radiography and micro-computed tomography, they showed that the nanodiamond-enhanced gutta percha could be used to fill the tooth.
Like the traditional formulation, the nanodiamond-enhanced compound did leave small gaps in the canal - where harmful bacteria could grow - but the CT imaging showed that the enhanced material filled the space just as effectively as traditional gutta percha.
"Validating this novel material in teeth extracted from patients serves as a strong foundation for the potential translation of nanodiamond-reinforced gutta percha toward clinical testing," said senior author Dean Ho, co-director of UCLA Dentistry`s Jane and Jerry Weintraub Centre for Reconstructive Biotechnology.
In the research`s second phase, the scientists tested nanodiamonds that had been loaded with amoxicillin, a broad-spectrum antibiotic used to combat infection.
The drug-reinforced nanodiamonds, when combined with the gutta percha, effectively prevented bacteria growth.
"The nanodiamond-enhanced gutta percha combines many desirable properties into a single platform, including vastly improved mechanical characteristics and the ability to combat bacterial infection following a root canal," said Dong-Keun Lee, a postdoctoral scholar in Mr Ho`s lab.
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