A Lesson in Microbiology from Rella Christensen, RDH, PhD





By Lexi Marino June 25, 2020

Rolando Mia, from Zyris, hosts a video series focused on the latest news, topics, and conversations happening in dentistry featuring dentists across the nation. In this special edition episode, we interviewed Rella Christensen, RDH and PhD to get her clinical research perspective in microbiology and dentistry to help our viewers find advice in a time where actionable information from authoritative sources is uncertain.

Watch this video to learn the following:

  • What makes up dental treatment particles and aerosols?
  • Is the 15-minute wait period suggested by ADA (originally suggested by CDC and then removed) sufficient according to science?
  • Proper N95 masks and how to make an educated decision for fit.
  • The science behind pre-treatment rinses, rubber dams, air filters, and overhead vacuums.
  • The importance of proper HVE use and how it’s commonly misused.

Rolando Mia:

Good day, everybody. Welcome to Dental Voice with Zyris. My name is Rolando Mia, and today we have a very special session of Dental Voice with a very special guest. I want to introduce you to Dr. Rella Christensen. Dr. Rella is an icon. I’m going to call her a “goddess” in our industry. She is one of the most knowledgeable people that I’ve met, I’m really excited that she’s on here. In addition to the experience that she has and the insight that she can provide here, she’s the person who directed the Expanded Function Hygiene Program at Colorado School of Dentistry. She’s a graduate of, of USC. So, fight on.

In addition, she’s a PhD in physiology with a microbiology emphasis. Her experience, her knowledge, and the research he’s done in our space is amazing. I’m really looking forward to is spending time with her today to hear her thoughts get some advice and her guidance. So, Rella, welcome and thank you so much for joining us. How are you?

Rella Christensen:

I’m going great, Rolando. Thank you for the invitation – I’m honored to be here.

Rolando Mia:

Awesome. So, the purpose of Dental Voice is to hear feedback and get perspective. Also, most importantly, to hear advice from people who have the ability to express that. So, what I’d like to do is start out with a big topic and that big topic is what everybody is talking about: aerosols. What’s the deal with aerosols and what do we need to know about them? Could you take some time to kind of take us through that?

A Microbiological Perspective on Aerosols

Rella Christensen:

You’re right in the fact that you say this is a very timely topic. However, I want to point out as we begin here, that aerosols in dentistry became an item of interest actually back in the 1960s, when the Air-Rotor Handpiece was introduced and some of the very best research was actually done during that time through the 60’s and early 70’s. Today we have other instruments of interest in the dental aerosol field, but I want you to understand that when we talk about aerosols, technically we’re covering a whole range of droplets that that we create dental treatments. Droplets ranging from quite large to very tiny. It’s the very tiny ones that are known as aerosols.

One of the things I’d like to do with us hygienists is to right here at the beginning, separate the cooler water from the treatment droplets and aerosols that are generated. The coolant water really shouldn’t be part of the discussion but that’s making a huge assumption. That’s assuming that all of us have met the ADA specifications for dental waterlines. That specification states, “500 colony forming units of heterotrophic organisms per mil, or milliliter of water.” A milliliter is a standard test tube covered on the bottom about a half inch up.

So, it’s not a lot of water but that 500 colony forming units of heterotrophic microbes per milliliter is actually the standard for drinking water in the U S. If we meet that in our coolant water, we can put aside that in our vision and just talk about what happens during treatment. The reason I bring that up is because so many of the ads are holding up an ultrasonic working tip and high speed eroder handpiece with all of this cooling water spraying all over the place and that’s really not what we’re talking about.

We’re talking about what happens when a rotary instrument on either a higher or low speed handpiece or the actual sonic or ultrasonic tip or an air polisher, when that actually hits the surface of the tooth, both super and sub gingerly, a lot of things happen and those are the particles that we’re talking about. Those particles can be little bits of tooth. They can be small bits of soft tissue, particularly when we’re sub gingival for crown preps and for ultrasonic scaling and sonic scaling.

All of the fluids in the oral cavity that would include saliva, crevicular fluid, puss, or exudate and blood. All of these fluids are kicked up into the air in various size particles. So, it is these “treatment particles” we’re talking about that are micro-laden and not the cooler water. That’s a long explanation, but it’s very important to make that that difference between the two.

Rolando Mia:

I understand and I appreciate the clarification around that. When you look at the coolant water, that’s the water coming out of the handpiece and that’s not as much an issue. The debris or what’s being ejected during the course of using ultrasonic instruments rotary instruments is the issue.

Dental Treatment Particles Vs. Coolant Water

Rella Christensen:

And you have to realize that the water, if the office has their dental unit water lines under control, that’s the same water. You go over to the sink, you fill up the glass – it’s the same water you use to cook with, or to bathe in and so on. These are heterotrophic organisms. They are present, but these are organisms that are not pathogenic under almost all circumstances except possibly, highly immunocompromised people. Then we have to talk about other things with water.

Rolando Mia:

I so appreciate that. It’s interesting too, because when people talk about COVID-19 and from what I’m hearing, the matter that’s being ejected from the actual patient can contain a bio burden. So, that’s what we have to be mindful of, correct?

Rella Christensen:

That is correct. In fact, it isn’t a matter of, “can contain”, absolutely contains the oral fluids and those harvests off little tiny pieces of issue and the microbes. I don’t think most coalitions realize the concentration of microbes in saliva, when we grow them and Petri plates, there’s just thousands of colonies growing on top of each other.

Even on the outside of a tooth that appears to be dry and clean, and it’s isolated with a rubber dam. We can swipe across that with a little micro brush with medium on it, and then culture that we get back can get anywhere from 15 million up to 2 billion organisms, just that little tiny microbrush. These are the organisms that are associated with the patient. If the patient has to be ill there are highly likely to be what organisms causing that illness, either bacteria or viruses, or even some other life forms.

What Does Science Say About Letting Aerosols Settle?

Rolando Mia:

In looking at all the information that’s out there very recently, I believe there was a webinar that was done by the CDC. They mentioned that they’re potentially going to suggest waiting, 15 minutes in between patients to enable or to let aerosols settle before going to the next patient. What are your thoughts on that?

Rella Christensen:

Well, I’m going to go back to our first comments. Aerosols, that term, if you were to look that up in a medical or scientific dictionary, you would see that these are very small particles measured in microns in sub-microns.

What’s going to settle in that first 15 minutes are going to be what we would call droplets. These would be fluids containing bacteria and viruses and particles of food and all kinds of debris that might be in the oral cavity. The actual aerosols, which are measured in low micron and sub-micron numbers, these take a matter of hours and sometimes several days before they before they actually settle. So that 15 minutes is for the big guys that are that are the more obvious ones. They generally do settle in about the first 15 minutes.

You would be interested to know, Rolando, that we’re creating these kinds of particles here using humans, as well as, as various types of instruments, everything from smoke to actual gritty little particles of known size actually placing virus’s phage bacteria. These are viruses that infect bacteria and creating actual aerosols – very tiny down in about the 0.5 to 0.3 microns in size. We create them purposely and then try to clean them up and also count them with laser particle counters.

So, that first 15 minutes are the big guys. You’re going to have to wait longer for the smaller guys. What I’d like to do is touch on some of the things that we can do now before even purchasing new pieces of equipment or a special technology.

You can do a great deal with products and equipment you have in the dental office right now.

Rolando Mia:

That would be great. What does that look like?

Protocols And Equipment For Reduce Aerosols

Rella Christensen:

Well, you know, we’ve actually kind of put together a set of steps. I think all of us are familiar with step one. That is don’t allow people who are ill inside the office. You’re seeing this all over the country now, as far as taking temperature readings and these types of things. We also put some of these little flat gloves. Can you see this on my screen here is not showing me what I’m showing, but just these little flat plastic press gloves.

We put those on our patients before they enter because it’s more certain than trying to disinfect their hands. In our particular facility, our patient chairs patient treatment chairs enough of them have an arm that the patient is going to grip it with their hand, or at least lay their hand on it. So, that would be number one.

Screen People Who Are Ill

Rella Christensen:
A lot of businesses and professional offices are using questionnaires. That’s a possibility too. Eventually if things continue, which we expect them to those of us that work in my virology and microbiology all the time expect this type of thing that we’re experiencing now to go on for a while.

Maybe not the shutdown as we’re experiencing, but we’re going to be very cautious of for a period of months yet. In that situation, we’re hoping for a quick antibody test. Something where perhaps we can process it right there at the dental office and know if the patient has or currently does have COVID-19 or perhaps even something else.

So that would be point number one is trying to screen for people who are ill. In line with that, just yesterday, I was in put in a situation where I had to make a decision on a patient, but a fever just barely below a hundred who arrived someone who was a special needs patient and in his 20’s, and the mother had to get off work and drive him into the office and from a distance. I had to try to decide if we were going to go ahead and treat him, I decided to treat him and rely on my personal protection.

However, it was a little exciting for the whole time to really practice strict infection control all the way through. Cause we don’t, we know if he was really sick, he was just barely under a hundred, two tenths of a degree under a hundred.

Have An Efficacious Face Mask

Rella Christensen:
The second thing is to have an efficacious face mask. That’s an interesting thing. We’re all talking about N95’s, but for many years we have talked about mask called the critical care PFL – standing for positive facial lock, critical care PFL with magic arch. And this is how that mask looks. It’s a flat mask, but when you, when you hold it up, you can see how it bows out, are we seeing that? If I open this mask and if I take this mask, this one happens to be an ear loop version. You can see it has wire all the way around, and I gather it up here and then folded over on the bottom.

So, it has a very tight peripheral fit and then it has these bands out here that hold it away from my lips and nose. That’s very critical. You don’t want your mouth to touch your mucous membrane of your nose or lips. This is a Level 3 mask, and yet it has a 99% of filtration clear down to 0.1. That’s 1/10 of a micron. It also has better than a 99% peripheral fit if you put it on, right. It comes in an N95, that looks very similar, but it has two of the headbands. We no longer can go with the ear loops; these are going to pull that mask very tight.

Although it looks exactly the same, it has a little bit more filtration, which means that it won’t soak through quite as fast, but it is an N95 mask. It is registered as that with the NIOSH. It’s been available through Crosstex for many years. The critical care PFL with magic arch is available through like most of your major dealers, Schein, Patterson, Benco, and Darby. I don’t mean to leave any out, but an N95 mask will always be stamped as such. It must have that on it.

These are masks at this Level 3 that are a lot easier to operate in all day, and yet give you a great deal of protection in an outpatient clinic. So, you have your choice, N95 masks come in all kinds of styles, they can look like a little snout, or they can look almost like a gas mask, or they could look like the mask I showed you here.

So, you want an efficacious mask. What does that mean? It fits tightly at the periphery and it has high filtration. It does not touch your lips or your nostrils. If you’re wearing anything else, you’re below standard, as far as a mask with efficacy. I have shown you here the critical care PFL is the only one that we found that really has a great seal at the periphery shy of being a N95. If any of you have worn N95 you know that they fit tight because you’ve got to have that peripheral fit or else your organisms are breathed right in.

We actually measure that using a blue dye test where we created aerosols and put a human, right in the chamber with those aerosols and could watch to see where the impregnation is. You must have the peripheral fit as well as the high filtration.

The Controversy Behind Pretreatment Rinses

Rella Christensen:
The third thing is something that’s highly controversial, and that would be a pretreatment mouth rinse. Now we in hygiene have used Chlorhexidine for many years as a pretreatment and post-treatment at home in many applications. However, Chlorhexidine is notorious for being a poor antiviral. We’ve done the work on that in our lab, and I can absolutely vouch for you if we’re after viruses, that’s not the way to go, but it’s great for bacteria.

Particularly for those that are implicated in periodontal disease anaerobic rods and the types of organisms we generally fight. Hydrogen peroxide was suggested by a pulmonologist up in Seattle at about the 1.5% to the rinse with and even to gargle with it. There’s other research in Europe that says, “Don’t, you dare gargle with it, it will burn the tissues in the throat.”

Interestingly though, that pulmonologist said any antiseptic mouth rinse, and I’m going to show you one here. I hope you can see this. This is your old friend Listerine, but it’s the original formulation Listerine, not fancy ones they’re putting out now. This original formulation of Listerine is the stuff your grandparents used and it’s potent not only does it have several essential oils in it, but it also has 27% by volume ethyl alcohol.

This is the same kind of ethyl alcohol that you would have in a scotch bourbon, beer, or wine. That is a very potent antiviral. So, you’re going to have to make your decision on the pretreatment route mouth rents. There are a number of recommendations pulled on iodine at about a 2% or 0.2%. There is no “with patients” research on this for patients who actually have the COVID-19 disease.

So, we don’t have data to on a mouth rinse showing efficacy against the SARS-CoV-2 virus. So, all of this is laboratory work and it’s minus the mucin and the debris in the oral cavity that these mouth rinses would have to penetrate because the viruses are wrapped in all of this debris and the mucin in the saliva. We’re left without good data. We have data with viruses. We have data with bacteria, but not with the SARS-CoV-2 to virus.

I would rather not work with that in my lab right now. I’m an old lady and in the susceptible category. So, all I can tell you is there’s controversy. There has not been any human research with the virus of interest. So what would I personally use?

High Ethyl Alcohol Containing Rinses

Rella Christensen:
I personally would use in high ethyl alcohol containing rinse. A lot of those are no longer on the market. They were taken off the market because there were people that objected to them for two reasons. Number one, people were buying the mouth rinses to drink and were getting drunk. And number two they were destroying tissue cells in young children. So many mouth rinses, proudly proclaim that they’re non-alcohol containing.

That would be my first go to, I wouldn’t even hesitate Listerine original, which I believe you’ll be able to find that just a very fine, like at a Walmart or a Target, these types of national drug stores or variety store.

Hesitation of Rubber Dam, Rather Use An Advanced Dam

Rella Christensen:
The fourth point would be isolation of some type. I hesitate to say rubber dam because we don’t use that so much anymore.

However, some of you may be familiar with the OptraGate, which is a quarter pipe of a dam that you can see the little picture here. I think most hygienists are familiar with this product, very handy for bleaching patients and other types of things. Any kind of a dam, not so much the OpetraGate, but something like your Isolite. Some of the hygienists use these.

A standard rubber dam where you have isolated the area you’re going to work on away from the lips and the cheeks and the tongue and the pooling saliva under the tongue for hygienists that are treating teeth number 1 to 32 to even talk about about how dam isolation is difficult because they’re also using or needing access the sub ginger tissue.

So, I’m going to list the rubber dam or dam isolation as a step that is helpful in controlling the treatment particles, but less helpful to the hygienist in our everyday work.

Everclear and How To Use It

Rella Christensen:
Now I’m going to mention to you something you’ve probably never heard before. This is where you start hearing from the nerves of the world or the microbiologists. Have you ever heard of Everclear, Rolando? You ever heard of this product?

It comes in as pure food grade, ethyl alcohol. If I have some gourmet cooks in my group, they use it for flambé and other things in their dishes. You buy it at a liquor store. It has a couple of different dilutions, 75.5% and 95%. Here in Utah, we have to go to a liquor store, but that I believe is true in many States. Sometimes you can get at where cooking supplies are available because of its being used in a flambé. You know, when you throw in a dish it goes, “Boom.”

Think about it in terms of a micro brush, little tiny brush with a tip on the end, dab dish with a little bit of ethyl alcohol, dry off a quadrant where you’re going to be working and coat those teeth generously not sort of runs all over, but paint the teeth generously with your ethyl alcohol.

You’ll kills the organisms on the outside of those teeth. One interesting thing that we did not know but we published the information in a place where we hope that clinicians would read it. This was in November of 2018, this was in Dentistry Today’s first peer reviewed scientific article. What we were showing is our work in dental caries.

This is a tooth of hygienist, number 18 word, and it had this old sealant in it. Then we go in and we in a very systematic way with a little tiny eighth round bur excavate very small layers of the of the carious material at a time. And then over here, you’re looking at a map showing by color, which genus and species of organism.

Over here on the side, right on this side, we’ve actually shown you the number of these organisms. What we found with this particular patient is by taking our little micro brush and just wiping it over the outside of this tooth, number 18, just a streak, and then dropping my brush into medium and culturing it, and then actually growing up those organisms. We got over 2 billion organisms on that micro brush and I’m hoping that that gives you some kind of an idea of what you’re up against microbiologically in the oral cavity.

So, we have suggested the use of this product. You could go tooth by tooth or in sections as you’re using your Sonic or ultrasonic scaler, or even your polisher and lower those organism numbers. You’ll lower them about down to almost non if you’ll put this high-grade ethyl alcohol. This is not something you would rinse with. It’s going to feel like it’s burning your tissue unless you happen to be somebody that that’s able to, what do they call those little tiny things that the guy goes like this in the Western movies?

Rolando Mia:

Shot glasses.

The Proper Use of HVE for the Hygienist

Rella Christensen:
Sure! Shot glasses.

I understand that just burns all the way down. Basically, this is strictly to use to paint on the teeth and kill those microbs. This work, we put into Dentistry Today with Eric, because we knew it, a lot of people would see it there. It is being prepared now for the Journal of Dental Research where our research colleagues will read it. I dare say probably very few dentists and probably no hygienists will see it there.

The next point that I’d like to bring out would be the most important of all and Rolando you and I had a lot of fun with this, this little friend of the hygienist. This is your high velocity evacuation tip and the hygienists will also very liberally will use the saliva injector tip.

These tips are quite different from one another. The saliva ejector tip is really made for picking up pooled saliva. Whereas this guy here, this is designed to pick up the treatment coolant water, as well as the treatment aerosols. We have wonderful data having studied dental treatment particles three times. Now, this is our third time. The first was near the end of or about mid 1980. The second was about 1992 when air abrasion cutting was very popular. We had to look at what these guys can do. This is for your pool substances and hygienists love them because they are not as likely to pick up the, the loose mucus membrane at the bottom of the oral cavity sublingual.

But this guy here, if you will look at it was designed actually in the 50’s and 60’s when evacuation came into dentistry. We didn’t have such a thing before then. Before then we use cuspid doors and patients would lean over and spit. Whereas this meant the patients stayed in the chair and you would suck the material out. There was a gentleman actually in Salt Lake City by the name of Dr. Albert Thompson, who brought this technology into dentistry. What I want you to notice, Rolando, you remember why this one end has a hole in it, and this other end doesn’t?

Rolando Mia:

To decrease evacuation.

Know Where Your Office’s Suction Pump Is

Rella Christensen:

That’s right. Sometimes you have more evacuation than you want, and you can just turn the tip around and this side has this hole in it. Ideally your office is very familiar with your suction pump. We are finding though that there are hygienists and assistants whenever never seen the suction pump.

It’s often located several floors down in a basement and nobody knows very much about it. Some suction pumps right at the pump have a screen or filter that needs periodic cleaning and changing. You hope you don’t get assigned that duty. It’s an unpleasant one, but it needs to be done and often.

I think every hygienist knows that chairside associated with this and with this there’s a place in the unit where there is a little screen there. So that in case you suction up somebody’s crown or a restoration it won’t go to the sewer, but it’ll only go as far as that little screen.

That little screen picks up a lot of other things too and needs to be cleaned daily. Ideally it would also go into the glutaraldehyde overnight and be installed new each morning. So, when we talk about suction, let me tell you the important part of it, this little guy right here, we can prove to you will actually take care of anywhere from 90 to 95% of your treatment particles of all sizes, but you’ve got to service it correctly.

You’ve got to maintain it correctly. You’ve got to use it correctly. We just talked about servicing it. You need to know where the pump is. You need to know where these screens are chairside and some pumps don’t have them at the pump, others do. Maintaining means cleaning those. You may want to get your equipment person out and ask them to look at your pump and learn from them about the pump.

But this little guy here, 95% of what you’re creating can be picked up at the site of its generation. So, this is your friend. The other five to maybe at the most 10% that we can pick up with perhaps HEPA filters. Perhaps we can pick it up with chemicals and we’re going to talk about that in just a minute, but Rolando, I think I saw you had a cute little mannequin there.

Rolando Mia:

Great. So if I understand correctly, here’s our friend and you can see that I have it on backwards. Is that correct?

Losing the Capability to Control Treatment Particles

Rella Christensen:
Well, unless you purposely want to attenuate to suction. And sometimes when you’re, when you have a patient that has a gingival recession, you’re very close to the bottom of the mouth. Or if the doc has his suction pump or his or her suction pump adjusted from maybe multiple users using it at the same time and you a hygiene’s happened to be in the office, perhaps alone that day, you’re going to have more suction than you want.

So now you may need to use that end with the hole on it, try to use the other end. Show them the other end, Rolando. Here is where you get full suction. So, try to use that end. If it’s not going to work for you. You can always pull the tip out and turn it the other way. If you’re forced to use your saliva ejector, you have lost your capability to control your treatment particles at that 90% to 95% reduction.

This guy is your friend and what we were showing Rolando, it has that 45-degree angle. You see how it has that angle and that squiggly on that angle. That is meant to get it very close to where you’re operating. Hygienists, if you are operating on the buccal surface, go back to a molder like a first molar or even a premolar, Rolando. Yes, I can.

Hygienists, you’re going to see that is designed to fit then on the lingual surface, and you want to pull your coolant water across the tooth. If you’re working with your ultrasonic, you need that coolant water because your ultrasonic tip can get quite warm. Particularly, it will be uncomfortable on the patient’s root tissue. It needs to be moving all the time and it needs that coolant water.

We Don’t Want To Do Away With Ultrasonics

Rella Christensen:
Not only that, our microbiology shows that the lavage from that coolant water is what really gives you a significant reduction of microbes in the pockets. So, we don’t want to do away with ultrasonic and sonic scalers. We don’t want to do away with that cooler water. We want to learn how to use it.

So though, I don’t know if you could get any closer, but can you see how that little squiggly fits around that tooth? You’re coming in, and for hygienists, you’re always opposite. If you’re operating on the lingual, then you’re going to circle around and try to suction from the facial or buccal side. I’m going to say something extremely controversial, but I’m going to stick by it and that is honestly, hygienists are long overdue to have an assistant working with them for their suction and their air.

I’ve worked with assistants a number of times in my hygiene career, which was ancient. I’m a nerd these days and don’t do a lot of hygiene but in order to be convincing to the one dentist I worked with, I actually hired kids that were in a junior and senior high school from 2:30PM – 3:00PM on and treated the patients where I needed that kind of 1:1 tooth at a time type of suction and air. The kids were delighted to come.

They were paid the minimum wage and learned a lot about dentistry and so on. But I think today, if we can manage to find people in my opinion, they do not need to be a trained assistant, however, if they are, or if it’s legal in your state another thing that one of my friends showed me how to do was to work in adjacent operatories. I was doing the scaling and would then send the patient next door for polishing and finishing work. We could see a lot of patients and we could do a really good job on them that way.

So these are some suggestions of ways to make that suction work for you. This is so important.

Rolando Mia:

Thank you for that. To your point, I believe although the hygienists or the dental assistants know this anytime you can refresh the technical use of each of the instruments, because there’s so much going on, is helpful. So, screen your patients, make sure everything’s okay. Don’t treat sick patients. Obviously, the masks are very important, and I love the context around N95, as well as others.

Quick question. What are your thoughts on the clinicians or the people who take the mask? We’ve heard a lot about this, they’ll pull them down and hang them underneath their chin.

We Must Wear Our Masks Properly

Rella Christensen:

Did you really just ask me that?

Rolando, I would hate to see that in a dental office. I have seen it in grocery stores. I’ve seen it in the salons and places like this, where people are not wearing a mask routinely. However, in dentist, hygienist, assistant situation, face masks have been where the OSHA bloodborne pathogen standard, which incidentally is a national law.

The OSHA bloodborne pathogen standard is not a suggestion or a guideline. It went through both houses of our Congress and was signed by the President of the United States. This is a law and essentially masks and gloves would be very routine for us. When you go into a mask that does have a tight, peripheral seal, not tight, that it’s uncomfortable, but enough that it’s a true seal. Now you have to breathe through the mask, not from around the border and you’ll have to get used to it.

I remember one time shortly after I started wearing it, I had to go upstairs, and I had my mask on and I just left it on. I ran up two flights of stairs, Rolando, and I just about passed out at the top because I wasn’t conditioned yet. It’ll take you a couple of months. It’s like a runner. When you decide to take up running you’re going to have a little bit of a hard time getting your breath for a while until you open up the capacity of the bronchioles in your lungs, and then you get used to it, but people will lower the mask cause they’re having a hard time breathing.

Some of them are honestly feel claustrophobic, but I would hope any of us who are hygienists, assistants, or a dentists would have worked past that. I hate to see that in a dental office.

Rolando Mia:

Thank you for that. I appreciate it. We’ve got a lot of viewers here and there are several questions. There are several that, if you would, may I share with you and get your thoughts on them?

One here is from Lance Murphy and he asks, “When will CDC, FDA, NIH or recognized authority study dental aerosols versus medical aerosol generating procedures. For instance – intubation results from deep coughs in the chest versus spray from a high-speed burr or an ultrasonic scaler?”

Dental Aerosols Vs. Medical Aerosol Research

Rella Christensen:
Now that’s a very good question. We’ve spent a lot of time effort and our own funds, as you know, this is a nonprofit foundation. So, we do take funding from manufacturers or from the government – it’s up us to get funding. So, we have done these studies here. I can tell you that both medicine and dentistry have problem.

Yes, you’ve got intubation, but you also have your orthopedic surgeons that use rotary instruments. But they’re generally in an OR and they have the same problems that we have in dentistry where they’re shooting particles of bone, blood, and body fluids and exudate, plus, etc., all over everything. It’s not just dentistry. Anybody that’s using any kind of a rotary instrument or any kind of a powered instrument against either hard or soft body tissue.

Honestly, I wish you would look back a little farther in the literature and you’re going see some excellent research done in the 70’s in tuberculosis sanatoriums. I’m not even sure we have any of those anymore, Rolando, but this was a big thing during the 30’s, 40’s, maybe even the 50’s, but and they’ve gone into these sanatoriums, worked on people, and then cultured the air and found plenty enough tuberculosis bacteria to infect anyone who was there.

So, the research is there, but because it’s a little older, it’s harder to pull it into a Medline search. What else would we do though, in a recognition of this viewer’s question, I would want you to know that today we would group equipment that you could buy into physical, chemical ultraviolet, and then various ionic and electronic and combinations of those.

That’s what we’re testing right now. You might be interested to know what the real nerds in the world use. I showed you just very briefly what we placed in dentistry today, back in 2018. In securing that data, we have to have a sterile environment. So, we have created a dental operatory right in the middle of a true microbiology lab with a couple of anaerobic chambers, with a DNA sequencer, and an operating microscope and an in amongst this is our patient.

Our ability to cut with a dental hand piece – that situation, part of our controls is to prove that the air is pure. What we did is we went to the actually the computer industry and looked at what was going on in the drug and computer industry, where they also need a very clean environment.

A Look Inside A Microbiological Dental Lab

Rella Christensen:
You can’t have little particles and little hairs falling on your circuit boards and into tablets and pills. Are you with me? So, what we have is an equipment that is 2ft by 4ft in size like a ceiling tile, and it is mounted on the ceiling can be hung, or it could be recessed in the ceiling.

We’ve used it both ways. And it is a series of HEPA filters. We put the patient in supine position and there are vents at the right and left shoulder about not maybe about 2ft up from the floor, if you can see that that would be right at the patient’s left and right shoulder, if they’re laying back flat or almost flat, and that those are the intake for the air, it goes up to the ceiling and then comes down.

Our assistant operator with dental, that happens to be me. So I can’t say it’s a dentist, cause I’m not a dentist. Also, the patient is bathed in this highly pure air, 100% the time. Yet our hair doesn’t blow, and it doesn’t need isn’t noisy, but it’s very clean air 100% of the time that the unit is operating. It’s operated at high. Why would I operate it any other way? I want the air to be clear.

So, that is an option. That unit today we called to price it out. We originally paid about $800 for it. When we bought it today, it’s 1500. We bought it about 20 years ago. But to show you the ease of obtaining very clear air, we actually have to open Petri dishes and locate them around us while we’re operating so that we can report those results.

These are part of our controls when we report microbes in teeth. So, you’ve got something that that’s, that’s that easy. You also have consoles that are sucking in the air over filters, and then exhausting into your operatory. These are the kinds of things I call them, “Roll in, plug in, use it.” We find that those will circulate the air, but only clean a 10x10x10 operatory, high ceiling, 10×10, maybe three, maybe four times in an hour.

Whereas the device I first described to you run on high, will clean it about 42 times. So there’s quite a difference in the purity of the air. You also have chemical treatments, you may have heard of what they call fogging and we haven’t tested those yet, cause it’s a little messier to do.

Extra Oral Suction

Rella Christensen:
There is interest in dentistry and what I call extra oral suction. Maybe you’ve seen these little square motors with the big long neck. We have one called the ages AEGIS. I think Schein is selling it. It was brought into our country by Chow group. We have tested that and it’s amazingly efficient. Now they all don’t have that design. It depends on the motor size, depends on the size of the hood. I call it a dish.

I like the one from Chow because the end is transparent. So you can look through it and operate. So see both that and the independent, a little roll in plug in, use it units, they’re all gathering in the impure air, running it over filters and ultraviolet infection, and then expelling it into the operatory.

Any of these could be engineered to expel outside or any of them could be engineered to expel and become a negative air. Your enemy is your heating air conditioning because whatever happens in the hygiene operatory or in the dental operatory down the hall is going to be picked up and carried every room in the office. Including bathroom and the patient reception area, anywhere, because it’s going to be picked up by your heating air conditioning.

It gets complicated if you if you want to get into that type of thing. This is why I like this this thing called the ECM Phantom is what we use in our clinical area. Cause we’re in totally pure air, 100% of the time, but not into the hassle with the heating air conditioning negative air situation that we don’t have to deal with that.

Discrepancies with Ultraviolet

Rella Christensen:
You also have ultraviolet treatment and I’ve heard some dentists say, “Well, look, I’ll just put in ultraviolet’s and then that will disinfect the aerosols.” But there are problems. You need to penetrate your droplets and your particles to the viruses inside and your ultraviolet has a distance. We use ultraviolet in our clean rooms. The distance from the lamp to the surface is 2ft and under. So you can’t just put your ultraviolet on the ceiling of your op and think it’s going to take care of your counters and your chair and everything else, because that may be anywhere from 6 to 8 ft away.

So, these things are a lot more complicated than meet the eye. There are ionic systems and what those systems are trying to to do is to make the particles larger, make them agglomerate so that they’re more easily picked up by a HEPA filters and some of them claim to disinfect as well.

Tell you honestly, bottom line I would advise moving slowly and letting the research come out. It will over the next year and a half, it takes time to get the equipment in, to do the science, to write it up, and then finally get it into publishable form that’s peer reviewed and time passes before the clinicians get a chance to see it.

Rolando Mia:

Thank you. I want to be respectful of your time. I have one more question here from Cindy. What’s the rationale for eight millimeter bore size. And is there a recommendation that goes along with the bore size to achieve that 90% aerosol reduction rate?

Rella Christensen:

No, there is a great question. I have not measured the bore size of this guy. I honestly don’t know what it is. Do you have a ruler? Can you measure that? It looks like to me, if we’re going to go in the English system, it’s shy of half an inch. Our research has done with that. And this is a very standard kind of a thing that you would buy for your high-velocity evacuation. Bore size, sometimes depending on the amount of suction it can impede it or sometimes it can actually make it better if it’s smaller, just depends.

Rolando Mia:

Awesome. So, when we were talking a couple of days ago, there was a sentiment that really struck me – it was meaningful. I was wondering if you would, and this is working together, the practice, the relationship between, you mentioned the context of helping the hygiene and the dentist. Could you could you just kind of take me through that again?

Team Relationship: Dentist, Hygienist, Assistant

Rella Christensen:
You bet I’ll tell you. Honestly, I practiced as a practicing hygienist and a number of different offices over a 20-year period. My husband moved in the course of his career doing a Masters in PhD and so on. So, we moved around quite a bit and I had an opportunity to live in five different states and work for a number of different dentists.

Honestly, I believe in teams and I believe very much in working together. We just can’t get things done when there’s an adversarial approach. I am seeing a little bit of this, a lot of it, an adversarial finger pointing type of a situation. The thing that makes it extremely difficult is sometimes the things that are that are desired are not available.

Like there were some dentists in our area, their hygienists wanted N95 masks, well, good luck getting them. You could order them, but you couldn’t get them delivered were on back order. The same is happening with this equipment. Many of the things we described, the long neck, in the cup, and the roll it in plug it in, the fogging and so on.

We’re seeing that many of the distributors are advertising, but they don’t actually have them. Maybe they’re coming from outside the US and they’re going to sell them, but the equipment’s not actually here. So, the doc puts in an order and week after week it’s not arriving, and they can’t install it. In the meantime, there’s a desire to start again.

That’s where I think, honestly, Rolando, the team needs to sit down and that would include everybody. I would include the janitorial staff, as well as the assistant, hygienist, dentist, and front desk. Sit everybody down and say, “Hey, we’d like to get started again. What, do we need to do that? And can we get what we’d like to order? How are we going to make this happen?” See if they could work together and see if they want to start certain procedures and see where people feel comfortable.

We’ve been in a number of offices with our dental materials studies over the last three weeks. I’m going to tell you something that I’ve noticed here in Utah, the hygienists are the most concerned. The assistants are somewhat concerned.

The dentists are somewhat concerned. The patients are not concerned, and we’re hands on with the patients because we’re making impressions of our restorative materials and taking photographs and so on. The ones we’ve seen have been very happy to be there, glad things are up and going again.

Most of them are coming in without masks and they’re getting their temperatures taken, but they’ve been to me, honestly, amazingly unconcerned. So, I’m wondering how all of this is going to shake out, but I would say that we need to work as a team rather than point fingers. If you feel your employer is just not able to satisfy you for goodness sake, maybe look and find someone who does rather than arguing and making issue.

Rolando Mia:

Thank you for that. The, the sentiment of coming at it together, taking the time to sit down and say, “Hold on a second, we’re doing everything we can.” I think it’s important because when we’re stressed, sometimes we become caught in the moment and to be reminded of that, it’s always pretty cool. So thank you.

Rella Christensen:

Rolando, the expenses go on and the income stops, and we have to be empathetic to that. I see it all over all around me, where some of you receive a salary. So, you’re not worried about things like overhead and the constant billings for water, rent, and that sort of thing. You want to want to try to have this thing called “empathy”, put yourself in the other guy’s place. Yeah.

Rolando Mia:

Thank you. So, first of all, I can’t thank you enough for taking the time to share that with us. The information that you’ve provided is so meaningful. I so appreciate it. First of all, thank you for the time. Thank you for your guidance and expertise. There’s a grace that I feel with you that you really genuinely care. It’s one of the things that is so engaging about you.

I can’t say enough, and I’ve learned so much, not just now, but also during the other times that we’ve spoken. You’re also the head of the TRAC Research which is an incredible program. I love the research. We look forward to any additional information you can provide. For our viewers, thank you for joining us and spending time with Dr. Rella Christensen.

If you’d like this information, please feel free to share. If you have any additional questions, let us know. Dr. Rella, if people want to contact you, what would be the best contact for you at the organization?

Rella Christensen:

You have that Rolando, you’ve done our email, that’s the best way. Rella@tracresearch.org and we’d be happy to help lend the information we know.

Rolando Mia:

You are a Dentalwoman and a scholar. Thank you for your time. Please be safe and look forward to speaking with you again, maybe sometime in the future, when more information is out, we’d love to have you join us again. All right. Take care. Have a great rest of your week.

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