Case report: Prepping teeth with no water spray or aerosols

By Dr. Joe Blaes, contributing writer

July 29, 2020 -- As dentists during the worldwide pandemic, the greatest enemy facing us is the aerosols we produce with our handpieces and ultrasonic devices. Many restrictions on the use of a treatment after producing aerosols have been placed by government and professional organizations. Our greatest concerns were protecting our patients, our team, our family, and ourselves in every way possible.

Our team came together to examine everything we knew and did and what our fears were. Having always been committed to first-class infection control, all we had to do was to add the extra personal protective equipment (PPE) to our protocol. We would then develop the exact wording to communicate to every patient, easing any concerns.

Handpiece and aerosol
All images courtesy of Joe Blaes, DDS.

While the office was closed due to the mandates from the ADA and the state of Missouri, everyone on the team was asked to watch a number of webinars, then send in a link to their favorite webinar for the entire team to watch. In doing so, each listed four things she had learned and wanted to use to ease any patient anxieties and ensure safety. This time was a great bonding and learning experience for all of us. We came back even stronger and more enthusiastic than ever before.

Many of the webinars were about the danger of the aerosols that we produce while prepping teeth and how hazardous this was to everyone in the dental office. Some of them promoted expensive devices that were supposed to control the aerosols. However, I have been using a rubber dam in my practice from the beginning, thanks to my mentor, Roy Wolff, DDS, who insisted I use one for every procedure. If my dental assistant is using the high-volume evacuator (HVE) correctly, she can easily control most of the aerosol produced by the handpiece and the rubber dam seals off the rest of the mouth, which inhibits being exposed to the virus and bacteria in the mouth.

I watched a webinar featuring Gordon Christensen, DDS, MDS, PhD, and Rella Christensen, RDH, PhD. Gordon said he has been prepping small class I, II, III, IV, and V restorations without air and water sprays for years. He stated that this was 60-year-old research done by the University of California.

This started me thinking about one question: What if I could do larger restorations like crown preps, inlays and onlays, and veneer preps without air and water sprays? If I could do this, it would protect everyone in my office.

Flir thermometer

I started a research project to prove that the temperature of the tooth being prepped did not increase enough to damage the pulpal tissue, using a highly accurate Flir TG54 spot infrared (IR) thermometer to measure the heat of the extracted teeth being prepped with carbide and diamond burs and no water spray. The constant air flow from the handpiece was not turned off, so the tooth was still receiving some cooling effect.

The potential damaging effect of temperature increase on pulpal tissue during dental treatment has always been a concern. An in vivo qualitative estimation of the temperature increase resulting in trauma to the dental pulp was published by Zach et al. They showed that healthy pulps failed to recover from an intrapulpal temperature increase of 52° F in about 60% of the cases, while 15% of the teeth heated to 42° F failed to recover.

The protocol began with the dry prepping of extracted molar teeth using both carbide and diamond burs. I dry prepped class IV and V preparations and crown preps and I sectioned teeth. During these procedures, there was never more than an 8° F increase. A normal amount of pressure on the handpiece was used to cut the tooth at the normal speed that I use in the mouth. In an attempt to increase the temperature, the pressure was increased on the diamond burs. However, there was no increase in temperature. This procedure was done on more than 60 teeth and the results were the same. Each procedure was videotaped with the Flir IR thermometer results in view. To decrease thermal damage to the pulp during dry tooth preparation, it is important to limit bur contact time to within 20 seconds.

Thermometer showing temperature

Using this procedure in the mouth produces dust and debris that must be removed by the high-volume evacuator. Dry prepping the tooth produces an odor, but this can also be controlled by the HVE.

You must be certain that the HVE is functioning as it should. How? Rella Christensen has worked with engineers to determine how a dentist can know if his or her HVE is adequate. All you need is a 2-L bottle (like an old soda bottle); fill it up with tap water, then turn off your HVE in all of your treatment rooms. I would go into whatever you consider your main operatory, then turn on the HVE and put the tip into the bottle. It should be emptied in eight seconds. If your HVE takes longer than this, you have a problem that needs attention!

Recently, Mary Govoni, who is an expert on infection control, wrote the following: "It is frustrating and fearsome to hear dental professionals not taking the threat of exposure to aerosol production in dentistry seriously. It is also frustrating to hear that many dental professionals would rather accept respiratory protection that is less than optimal in their haste to reopen their practices. While I completely understand the financial impact that this pandemic has had on practices, the financial impact of a doctor or team member being exposed to or developing a COVID-19 infection would have an even greater impact."

There are more advantages to prepping teeth without the air water spray. Because this air water spray makes it difficult to see the tooth clearly when you are prepping, you will be better able to see what you are doing as you are prepping the tooth. This means more precise preparations. However, we have always been taught that high-speed handpieces must be run with an air water spray. What you may not know is that many high-speed handpieces need constant coolant water moving through the handpiece to keep it cool so the operators do not burn their patients' intra- and extraoral tissues or their own hands.

I have been using an electric handpiece for more than 30 years. I have used many different brands, but my favorite is the Bien-Air Evo.15 electric handpiece. All of the preparations described in this article were done with the Evo.15. With this handpiece, I will not burn my patient. The patented "cool touch" push button has heat-arresting technology that prevents any burns. Because this electric handpiece does not heat up, we can prep teeth with no water spray and no aerosols.

Joe Blaes, DDS, created a unique, insurance-free, fee-for-service general practice in St. Louis that emphasizes preventive, esthetic, reconstructive, and implant dentistry. He is best known as the former chief editor of Dental Economics. Dr. Blaes is a fellow of the American College of Dentists, a past president of the American Academy of Dental Practice Administration, and a founding member of the American Academy for Oral Systemic Health. He can be reached at

The comments and observations expressed herein do not necessarily reflect the opinions of, nor should they be construed as an endorsement or admonishment of any particular idea, vendor, or organization.

Copyright © 2020

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