Pre-clinical evaluation of 'cleaner burs' - for safer dental aerosol generating procedures

Many procedures that a dentist performs, including tooth fillings, require the use of a dental drill. Attached to the drill is a bur which is the short cutting tool that has been designed specifically to cut tooth surfaces. Dental burs insert into the dental drill and rotate at high speeds with water being used as a coolant to prevent overheating. At the beginning of the COVID-19 pandemic it was recognised that saliva containing large quantities of coronavirus could mix with the coolant water and encounter the fast-spinning dental bur. As a result, a fast-moving aerosol made up of billions of small droplets could be ejected from the patient s mouth into the room environment. Many of these droplets are contaminated with saliva, and possibly virus, and because of their small size they can remain suspended in the air for long period of time. Because of this there have been many changes in the way that dentistry is now provided including the dental staff having to wear enhanced personal protective equipment and a reduction in the number of patients that can be seen per day. In this project we will test new types of dental bur that have been designed to irreversibly mechanically damage any bacteria or viral particles that are emitted in aerosol droplets so that they are no longer a risk. Ultimately the aim is to make dental surgeries a cleaner environment for both the patients and the staff. So far, we have demonstrated that the burs have a significant effect in laboratory tests but we must now prove that they also work when a dentist is using the burs in the same way they would in real life. To do this we will conduct simulations using mannequins with an artificial mouth and with dentists carrying out a series of common drilling procedures. To test the effect of the new burs, we will use a virus harmless to humans, known as a bacteriophage. We will put bacteriophage into artificial saliva in the mannequin and measure how far it is spread in the dental surgery and how much of the virus then remains intact and capable of transmission. We have chosen a specific bacteriophage because it resembles the size and structure of the novel coronavirus, but the work is relevant to a wide range of microorganisms that are concentrated in the fluids of the mouth. If these tests are successful, we will be ready to begin trials in dental clinics with patients. During the course of this study we intend to discuss the technology with patient representatives in order to help us understand how best to design future clinical studies and identify any concerns there may be about the technological approach.