Andrew Wilson was joint winner of the 1st prize of the undergraduate category of the Premier Awards in 2011.
Andrew Wilson - Dental Protection and Schulke Premier Award winner discusses the hazards of air born particles and the safety procedures needed to avoid health problems. This is a short summary of Andrew's project that he submitted for the Premier Awards.
Particles suspended in the air can be more interesting than you think. When the Icelandic volcano Eyjafjallajokull erupted in 2010, air traffic across the whole of Europe was halted by dust... So it's not something that should be ignored. As well as having an effect on a global scale, dust can affect us on an individual level. Particles small enough to be inhaled into your lungs, known as respirable particles, can have wide and varied impacts on your health. The body has processes to remove particles from your lungs but this takes time. Most particles that land in your lungs will be wafted out by the cilia on the wall of your lungs in the form of a "bogey". However if a particle is small enough to land in your alveoli, it must be phagocytosed by a white blood cell. This can take months. If overloaded, these processes will stop. Inflammation is the result and damage to your lungs will follow, hampering your ability to breath - with possibly disastrous effects on your health. So how does this apply to dentistry? The risks of respirable particles in dentistry have been acknowledged for sixty years. Most dental activity produces dust or air sprays. This includes everything from preparing a cavity to mixing alginate.
Technicians in the lab are at risk too. Our study set out to find out the concentration of particles made during laboratory procedures, how big they were and consequently where they would be deposited in the lung and the health implications.
We analysed the air during the mixing and trimming of plaster and the trimming and polishing of acrylic within the orthodontic laboratory at the University of Bristol, UK. During the procedures, air was sampled by a personal data ram particulate monitor to record the concentrations of particles produced. A Marple cascade impactor was used to separate the particles according to aerodynamic diameter onto filter papers which were then viewed under a scanning electron microscope. The results were largely inconsequential. Most of the time, particles made in the laboratory were at safe concentrations well below the limits set out by the Health and Safety Executive. However, when we examined how plaster was mixed, our results were much more interesting. In the laboratory, a machine called a plaster hopper was used - this dispenses powder to be mixed into plaster. The instructions for the machine require the technicians to hold their mixing bowl up to the dispenser and pull the lever. We found that technicians were instead sticking their spatula into the machine, jamming it open and allowing the plaster to fall from a height, resulting in plumes of dust (image 1).
These particles, viewed under the scanning electron microscope, are plaster that was suspended in the air from the plaster hopper. These were the larger particles so would be deposited in your nose and could be safely picked away (image 2). These particles were much smaller and could be inhaled deeper into the respiratory tract as far as the secondary bronchi. The overall concentration of particles over a working day was very close to the limits for a work place set out by the Health and Safety Executive. Our results show that the improper use of equipment can have subtle but serious risks. It is important to look after yourself at work and, no matter how boring, you should always read the instructions.