Nanodiamonds may make root-canal treatment more effective
It has recently been discovered that mixing nanodiamands with gutta percha when undertaking a root-canal procedure reduces the chances of the infection returning.
Root-canal fillings are required when bacterial infection has penetrated both a tooth’s protective enamel and the somewhat softer dentine layer that underlies this, and has got into the nutrient-rich, nerve-containing pulp in a tooth’s centre.
Unfortunately, root-canals are complex and difficult to pull off, and it’s common for the infection to return to the tooth, either because the void left when the pulp has been removed has not been cleared properly or because gutta percha, the gum usually used to fill that void, has not created a satisfactory seal, allowing the bacteria back in. The idea of mixing diamonds into the gutta percha is that of Dean Ho, a bioengineer at the University of California, Los Angeles.
The diamonds are 4-6 nanometres (billionth of a metre) across. The nanodiamonds have 14 facets; the edges where these facets come together are sharp, and the facets themselves are covered with chemical groups such as amines, carboxyls and hydroxyls, which means that they are good at digging into and, therefore, adhering to surfaces, including the dentine lining of an evacuated root canal.
The surface chemistry of the nanodiamonds means that their facets are perfect for attracting and holding onto antibiotics molecules. The nanodiamonds, which are crystals of pure carbon, are unaffected by the harsh chemical environment that is the mouth. A second bonus is that nanodiamonds are cheap, because conventional mining and refining techniques generate them as by-products.
To test his idea, Dr Ho mixed nanodiamonds with amoxycillin, a common antibiotic, and let the mixture sit for five to seven days at room temperature. This gave the antibiotic time to adhere to the diamonds. He and his colleagues then added the diamonds to some gutta percha and shook the result with sound waves to distribute the diamonds evenly. They then measured their new composite material’s tensile strength and elasticity (both of which were about three times that of gutta percha alone), and its ability to withstand a variety of stresses. They also monitored the rate at which the antibiotic leaked from the diamonds, which only shed around 13-17% of their load during the course of a week’s monitoring.
With such encouraging findings, Dr Ho reckons that clinical trials on patients are now just two years away.
