Few things send a chill down the spines of grown men and women as the prospect of getting a root canal. Eighty percent of Americans are afraid of going to the dentist, with one out of every two polled dreading the infamous root canal the most, according to a recent survey by the American Association of Endodontists. Luckily, scientists have been working hard in the past few years to make future dentist visits a little less painful.
Researchers in China and Southern California are racing to develop easy-to-use devices that kill infectious bacteria by delivering a stream of ”cold” plasma, thereby cutting down on the number of patients who have to repeat root canal procedures.
Cold plasma, or atmospheric-pressure plasma, is ionized gas generated by applying brief pulses of high voltage to a controlled flow of air or mixtures of oxygen and inert gases, such as argon or helium. The resulting plasma is cool enough to touch. Cold plasma has caught the attention of biomedical researchers in the past decade because it has proved to be an excellent blood coagulator and sterilizer, making it ideal for surgical and dental procedures.
In a root canal procedure, the endodontist begins by drilling a hole in the infected tooth down to the root canal to reach the core of the tooth containing the blood supply and nerves. She then removes the infected pulp and sterilizes the root canal using a variety of techniques, including liquid antibiotics, which can sometimes be ineffective, and expensive lasers, which can burn the patient’s gums. Finally, the root canal is filled in, and a temporary filling caps the hole. If the infection was destroyed, a permanent crown can later replace the temporary filling.
Unfortunately, the disinfection step doesn’t always work. As many as 10 out of 100 patients treated for root canal infections return to the dentist’s chair for another round of treatment because the disinfectants failed to kill all the bacteria living deep inside the sick tooth.
Cold plasma might do a more reliable job, according to researchers. The latest plasma devices are capable of generating thin plasma plumes that can fit into a tooth’s root canal, which typically has a diameter of 3 millimeters.
At the University of Southern California, a team of engineers and dentists led by Chunqi Jiang have been working on a cold-plasma jet capable of forming a plasma plume that’s 3 centimeters long and less than 1 mm in diameter and that can reach all the way into the root canal. Jiang has used her plasma jet to kill saliva-derived biofilm, a slimy layer of bacteria that has shown some resistance to antibiotics.