A futuristic "plasma jet" that eradicates tooth decay without fillings could soon replace the dentist's drill.

In the study, published in the February issue of the Journal of Medical Microbiology, researchers found that firing low temperature plasma beams at dentin - the fibrous tooth structure underneath the enamel coating - reduced the amount of dental bacteria by up to 10,000-fold.

The findings could mean plasma technology is used to remove infected tissue in tooth cavities.

Researchers at the Leibniz-Institute of Surface Modifications, Leipzig and dentists from the Saarland University, Homburg, Germany, tested the effectiveness of plasma against common oral pathogens including Streptococcus mutans and Lactobacillus casei. These bacteria form films on the surface of teeth and are capable of eroding tooth enamel and the dentin below it to cause cavities. If left untreated it can lead to pain, tooth loss and sometimes severe gum infections.

In the study, researchers infected dentin from extracted human molars with four strains of bacteria and then exposed it to plasma jets for 6, 12 or 18 seconds. The longer the dentin was exposed to the plasma the greater the amount of bacteria that were eliminated.