Aerosol: Electric High Speed vs. Turbine?
Tobias Schwarz is responsible for the product portfolio restorative dentistry at W&H. Since there is more common awareness about the role of aerosols in infection transmission we are receiving many questions. What is the right high speed handpiece to use to reduce the formation of aerosols? And many more …
Do air turbine handpieces produce more aerosol than electric high speed handpieces?
The amount of water spray, coming from both kind of handpieces, is basically the same. The essential difference is the bur speed, that would have different acceleration effects on the water drops once they hit the bur as well as different air velocity at the area around the bur. Turbine handpieces run at approximately 400.000 rpm. Electric high speed handpieces are operated at 200.000 rpm, so half the speed of a turbine, therefore, the intensity of particle distribution is less. This has a beneficial effect on limiting the exposure of water spray generated aerosol into the dental operatory environment. Additional air, leakage at the turbine's head, caused by the drive air to run the turbine, increases the distribution radius of floating particles around the air turbine's head. This effect is also significantly less with electric highspeed handpieces. Nevertheless, W&H Turbine handpieces are known to produce noticeably less air leakage at the turbine head than the average product on the market.
What’s the purpose of water spray use with dental high speed handpieces?
High speed preparation procedures require effective cooling of the contact site between the rotating instrument and the tooth. This is important as the heat, generated during gross reduction of tooth structure, would otherwise cause significant thermal damage to vital teeth.
That’s why dental high speed handpieces are equipped with an ideally multi-directional water spray systems with 3, 4 or 5 ports directed towards the bur's tip. A further positive side effect is that the cutting ability of rotating instruments is supported as the water spray also cleans out debris from the cutting area of the bur.
How does water spray affect the formation of potentially harmful aerosol?
The water spray itself, as it comes from the handpiece, assuming appropriate decontamination processes are followed, does not cause an infection risk if the water quality is acceptable from the dental delivery system. It is only, when the water drops come into contact with the patient, where they can potentially absorb germs which will then rebound from any surface within the oral cavity and spreads as infectious aerosol.
Why can’t I just turn off the air used for the spray to reduce the formation of aerosol?
A water jet alone is not powerful enough and therefore does not have enough cooling efficiency for high speed preparations, which is why compressed air is added to create the spray. The increased moistening capabilities of the spray, consisting of small waterdrops, ensures much better cooling thereby protecting the vitality of the patient’s teeth!