Dryshield Isolation System

Dryshield is NOT a High-Volume Device

It's understandable why so many dental professionals could be deceived into thinking Dryshield is an HVE device. After all, it connects directly to your HVE vacuum line.

Further, since the pandemic, DryShield has claimed to provide high-volume evacuation for aerosol reduction, a statement Solmetex continues to make today. Here’s a screenshot taken from the Solmetex website to illustrate this claim:

Why High-Volume Matters

But the Dryshield adapter is NOT a high-volume device.

A quick Google search will tell you that to qualify as an HVE device, a dental instrument must have a minimum interior diameter of 8mm. Anything smaller than that is considered low-volume (LVE). Most saliva ejectors have a minimum interior diameter of no more than 6.25mm.

But, if Dryshield says they are high-volume, and they plug into your high-volume vacuum line, then they should be high-volume, right? Wrong.

A closer look inside your Dryshield adapter reveals the truth. Inside the lever of the adapter, there is a choke point. A small hole by which all air must travel. In other words, the point considered the minimum interior diameter.

As a dentist who paid attention to aerosol management during the height of the COVID-19 pandemic, you are surely aware of Stephen Harrel & John Molinari's study, which has been a leading source for the dental community regarding aerosol mitigation.

Harrel & Molinari's study titled, "Aerosols and Splatter in Dentistry," was published in the Journal of the American Dental Association in April of 2004. In this study, they state,

"The use of a high-volume evacuator, or HVE, has been shown to reduce the contamination arising from the operative site by more than 90 percent."

The authors go on to further explain and define high-volume evacuation when they write,

"It should be emphasized that for a suction system to be classified as an HVE, it must remove a large volume of air within a short period...The usual HVE used in dentistry has a large opening (usually 8 millimeters or greater)... The small opening of a saliva ejector does not remove a large enough volume of air to be classified as an HVE."

So, in other words, size does matter. Harrel reiterates his point, and the importance of a device to be HVE, not LVE, for aerosol reduction in a more recent study published post-pandemic. In this study published by Decisions in Dentistry in May of 2020, titled, "Dental Aerosols and Spatter Amidst COVID-19," Harrel writes,

"Almost all dental offices have an evacuator system that is capable of removing a high volume of air/droplets/aerosols from the operating field. High-volume evacuation is usually performed by an assistant using a large-bore, disposable evacuation tip. The inside diameter of a large-bore evacuator tip is 13 mm or greater. This large internal size allows for a high volume of material to be removed from the treatment area, and has been shown to reduce the number of bacteria produced during various procedures by 90% to 95%. Various high-volume vacuum devices that fit in the patient’s mouth ... are available that allow for high-volume evacuation without the need for an assistant. It needs to be strongly emphasized the routinely used disposable saliva ejector tip is not a high-volume evacuator. Even if the system is capable of removing a high volume of material, the small inside diameter of a saliva ejector is not capable of removing spatter and aerosols."

So, Dryshield's marketing claims of being an aerosol-reduction device are not research-based and are dangerously, recklessly misleading to the dental community. Clearly, the Dryshield adapter, with an LVE opening of less than 6mm, cannot remove enough volume of air to effectively reduce the number of aerosolized biomatter and bacteria.

How I Discovered the Truth

Recently, I noticed the levers on my adapters were getting harder to turn and asked my assistant to look into it. What she found was disgusting, and she brought it to my attention. After struggling for some time, she was able to remove the lever of the adapter only to find a large amount of accumulation of biofilm, a sticky layer of bacteria inside. This biofilm can potentially cause cross-contamination if not properly cleaned.

We had always followed Dryshield's cleaning and maintenance instructions by flushing the adapter and lines between patients and wiping the exterior with disinfecting wipes. We never autoclaved the adapters, as they were permanently installed at our dental chairs and there was no instruction to do so from Dryshield.

At that point, I asked my assistant to remove, clean and autoclave the adapters. There was so much build up, we ended up having to cut some adapters off the tubing as they would not come free after a long struggle.

The minimum interior diameter of the Dryshield adapter is actually less than 6mm. That is smaller than most saliva ejector tube holders!

No matter how much suction power a device has, the minimum diameter will limit and restrict all airflow. Remember, your LVE valve is connected to the same vacuum source as your HVE. The only difference between your LVE and HVE is the interior diameter.

I, like many others, purchased several Dryshield systems during the Pandemic. Convinced by marketing claims made by Dryshield, including testimonials from other bamboozled dentists, I believed that Dryshield would help protect myself, my staff and my patience from exposure to COVID-19.

Of course, this wasn't the only measure I had taken for protection, but it sure made me feel good to check HIGH-VOLUME evacuation off my list of COVID protection protocols. I should have done more research then. I shouldn't have trusted Dryshield, who positioned themselves as experts in High-Volume Evacuation and COVID-19 aerosol control.

During all of this, I noticed that the build-up inside the lever was blocking some of the airflow. At this point, I realized that, even build-up free, the hole in the lever (what I now call the "choke point") was significantly smaller than I expected for an HVE device.

I quickly compared this hole to my saliva ejector valve "LVE" and was shocked. This led me down a rabbit hole of research, followed by an infuriating trip along memory lane as I browsed through Dryshield's numerous misleading Facebook posts, still active today. See for yourself the many examples of Dryshield's false claims of aerosol reduction and high-volume evacuation:

I can't stand by and say nothing. I am so disgusted by this company, and want to inform the dental community so they don't end up stuck with a large investment of Dryshield equipment that isn't what it claimed to be.

Dryshield, Tested and Failed for Aerosol Reduction

In a peer-reviewed study published in BMC Oral Health in September of 2022 titled, "Aerosol reduction efficacy of different intra-oral suction devices during ultrasonic scaling and high-speed handpiece use," Dryshield is put to the test, and stacked against several other suction devices including standard low-volume suction straws.

Not surprisingly, Dryshield failed. According to the study, during use of a high-speed handpiece, "the Dryshield device allowed escape of significantly more particles than all other dynamic suction devices" including low-volume suction straws. This makes sense now that we know that Dryshield is low-volume.

What are your thoughts on this? I'd love to hear from you!