May 31, 2020

How does using a rubber dam for dental procedures help to prevent the spread of the coronavirus?

As dental offices start to reopen following the initial peak of the COVID-19 epidemic, their dentists will need to implement a new set of "standard" protocols aimed at reducing their patients' in-office risk of exposure to the coronavirus.

One very effective step is the use of a dental dam (rubber dam) with patients when performing those procedures where its use is applicable.

This post explains how using a dam helps to reduce the potential spread of the coronavirus from infected patients into the dental office environment. And answers general questions about rubber dam usage/effectiveness that patients tend to have.

What is a dental dam?

A dental dam, frequently also referred to as a rubber dam, is a simple barrier device where a patient's teeth being work on poke through holes that have been punched in a sheet of "rubber" (in most cases, it's actually a sheet of latex that's used).

A tooth with a rubber dam in place.

A tooth with a rubber dam in place for its root canal treatment.

The basic goal of using a dam is to provide the dentist with a more controlled environment when performing a tooth's procedure. This is referred to as "isolating" the tooth.
[If you need further explanation about dam usage, the page linked here provides details (placement, use, removal, post-op considerations, etc...) about rubber dams when used in conjunction with performing root canal therapy.]

How does placing a rubber dam help to prevent the spread of the coronavirus?

The whole idea is very simple. The tooth isolation that a dam provides creates a working field where the level of viral particles that might be picked up from an infected patient's mouth during their dental procedure and spread into the dental office environment as a splash or aerosol is significantly reduced.

A tooth with a dental dam (rubber dam) in place.

Diagram of a tooth with rubber dam in place.

Our diagram illustrates how this works ...

The green line you see in our illustration represents the rubber dam (most commonly a sheet of latex). And also shows the metal clamp that grasps around the tooth to hold the sheet in place.
(In our real-life picture above, the sheet of latex is pink, and you can also see the rubber dam clamp that's been placed on the tooth.)

Notice that ...

With the dam in place, the patient's mouth has now been divided into two parts, a wet and dry side.
a) The portion of the mouth underneath the dam. | The wet side. -

Everything underneath the latex sheet is simply that part of your mouth that you see when you open it. It's your tongue, gums and most of your teeth, along with all of the saliva that bathes and covers over them.

Of course, if a patient has been infected with COVID-19, a fact they may or may not be aware of, it's this side of the dam where the bulk of the virus will lie (primarily in the patient's saliva).

b) The portion of the mouth above the dam. | The dry side. -

This is the side of the dam that your tooth pokes through to and is the working field for its dental procedure. Because of the tight fit of the rubber sheet at your tooth's neck, the dam acts as a barrier that prevents saliva from seeping over to this side, hence our use of the phrase "dry side of the dam."

What's so special about the "dry" side?

The tooth, or few teeth, that stick through to this side of the dam can be washed off thoroughly, without then being recontaminated by saliva. And if perchance the patient does carry COVID-19, which helps to minimize the number of virus particles that are present in the tooth's work area that might be spread into the dental office environment while its work is being performed.

Sterile wouldn't be the right term to use for the conditions on this side of the dam but potentially sanitized is. Especially in comparison to the "wet" (saliva bathed) side, the number of virus particles on the teeth being worked on can be very significantly reduced, just by washing them off before their procedure is begun.

Why is this so important?

Performing dentistry is a messy process, and one prone to spreading the coronavirus if the patient is infected.

Studies have determined that COVID-19 virions are found in the saliva of infected persons and that that fact can play a pivotal role in human-to-human transmission (Sabino-Silva). And unfortunately, this issue makes the dental office environment one of special concern in the spread of the disease.

Section references - Sabino-Silva

Aerosols and splashing liquids are a major issue.

If you'll think for a moment, it should be easy to comprehend how messy the process of performing dentistry is. Surely each of us remembers a procedure being performed (probably more often than not) where afterward we've felt like our face has just had a shower.
  • The process of washing your teeth off or the need to wash your mouth out is usually accompanied by escaping mist and/or splashes of liquid.
  • Dental handpieces (like the dental drill used to trim your tooth) are purposely designed to create a cloud of mist as they are used.


And with both types of events, either a liquid splashing or an aerosol being formed, virus particles, if present, will be picked up too and spread into the dental office environment. With the result being one where exposed surfaces and objects can become contaminated, and people infected too.

The potential scope of in-office contamination and virus exposure is daunting.

Surely by this point in our discussion, you've started to realize how difficult the dental office environment is when it comes to preventing the spread of the coronavirus.

(For further background information, read our page: Issues associated with the spread of COVID-19 in your dentist's office.)

Some pertinent distances to consider.
  • Splashes and splatter - This type of debris, generally categorized as being 50 microns in size and larger (with some bits being quite visible to the naked eye), is composed of air, water and/or solid substances.

    As it's ejected from a patient's mouth during dental procedures, the mixture travels in an arc until gravity finally pulls it down to land on exposed surfaces. The debris may travel as far as 120 cm (4 feet) from its point of origin.

  • Aerosols (airborne droplets) - By definition, aerosols are composed of liquid and solid particles measuring less than 50 microns in diameter. Particles of this size easily enter a person's respiratory system.

    A paper by Turkistani reports that the mist expelled by a dental drill can stay airborne for a distance of 2 meters, which is about six feet.

    Even more troubling, the particles themselves can remain airborne for an extended period of time, thus allowing them to filter throughout the dental office environment.


With those distances and points in mind, now imagine sitting in your dentist's chair. Then, run through your mind all of the objects, surfaces, humans (office staff and other patients), even return air ducts, that lie within that reach.

Section references - Turkistani, Szymanska

Here's how a dental dam prevents COVID-19 spread.

Taking all of the issues discussed above into consideration, the importance of diminishing the level of coronavirus particles that are available for spread when dental work is performed should become abundantly clear to you.

And that's where the dentist's use of a dental dam with all patients for all procedures where it is applicable can play such an important role in keeping you and everyone else in their office safer.

The use of a rubber dam allows for a cleaner working field.

The portion of a tooth that sticks through a rubber dam can be extensively washed, with the waste liquid then suctioned away. And doing so is able to remove a very substantial amount of the viral particles originally found on and around it.

And because the dam's seal against the tooth is watertight, no saliva can seep back onto it to recontaminate it and its work environment.

That's different than every other isolation or virus reduction method your dentist has to use.

There are some alternative and/or adjunct methods your dentist can also use to reduce the level of virus particles potentially escaping from an infected patient's mouth during their treatment. But none are as effective or predictable as the use of a rubber dam. Here's why.

a) Other tooth-isolation methods.

As an alternative to fitting a dam, a dentist might isolate a tooth by way of packing cotton rolls around it, possibly in conjunction with the placement of a dedicated suction device nearby.

Even so, it should be fairly evident to anyone that the level of cleanliness achieved could never equal that of the dry side of a rubber dam. And, of course, recontamination of the work field with saliva is always just one emergency swallow away.

b) High-speed evacuation.

It's true that the extensive use of a dentist's high-speed suction system can significantly reduce the level of liquid and aerosol that escape from a patient's mouth. (This is the "strong" suction device that all dental offices have, routinely use, and has probably snared your tongue a time or two.)

This technique should be implemented whether a dam is placed or not. But utilizing suction alone is only a way of attempting to trap infected moisture (a feat that will never be 100% effective). In comparison, a dam actually helps to prevent the moisture from ever containing a high level of the virus in the first place.

c) Oral rinses.

Some studies have shown that the use of a pretreatment oral rinse can help to reduce the level of the coronavirus found in a patient's saliva, but not totally eliminate it.

So, once again, our counter here is that the use of a rubber dam both predictably and substantially reduces the number of virus particles associated with the tooth being worked on. That's much different than what can be accomplished with a rinse.

Overall, how important is the use of a dental dam?

When applicable, there's no measure that your dentist can take that's more effective or predictable in reducing the release of coronavirus particles from an infected patient's mouth into the office environment during their procedure than placing a rubber dam.

Questions and answers about the use of a dental dam to prevent the spread of COVID-19.

Does using a dam for your procedure help to protect you?

No, your dentist's use of a dental dam for your procedure helps to protect others. In the off-chance that you carry the coronavirus, it helps to prevent it's spread from your mouth into the dental office environment.

In some ways, the use of a dam is analogous to the face mask wear the general public is asked to practice. The primary benefit of the mask lies in helping to contain the infective droplets you might spread to others if you are infected.

Can all dentists offer the use of a rubber dam?

Almost certainly. All dentists were trained in the use of a dental dam in dental school. And, once again almost certainly, its use was probably mandated by the school's clinical faculty when applicable procedures were performed for patients. (That's because its use almost always provides benefits for performing the procedure at hand.)

The instruments needed to place a dam are comparatively inexpensive, as are the disposable sheets of latex used. And in fact, if your dentist performs root canal work (for which using a dam is considered the required "standard of care"), they'll already have all of the needed items on hand for performing that procedure.

What dental procedures can a dental dam be used for?

  • In dental school, your dentist was probably required to use a rubber dam for essentially all filling placement and endodontic (root canal) procedures.

    That would include white (dental composite) and metal (amalgam) fillings, conventional (orthograde) root canal treatment, and post placement. A dam can also routinely be used with inlay placement.

  • A rubber dam tends to interfere with restorative procedures, like crown or bridge placement, where portions of the tooth that lie at or below the gum line must be accessed. A common exception is porcelain veneer placement, where a dam is often used.

    However, with just minor modifications and the use of some creativity, it can be possible to use a rubber dam even for these types of services. (Heasley, Romero)

  • The use of a rubber dam is contraindicated for any procedure where a significant aspect of the treatment involves gum tissue manipulation (periodontal [gum disease] treatments, teeth cleaning, tooth extractions, etc...).

Section references - Heasley, Romero

Does using a dam have the potential to compromise the outcome of my procedure?

For applicable procedures, the use of a dam usually equates with performing the highest caliber of dental work. Placing one gives the dentist a much more controlled environment, which is usually a giant plus for the procedure being performed.

We'll also point out, like we've stated above, that the use of a dam is usually mandated by dental schools for those procedures where its use is applicable. If your dentist uses one, and especially if they have a history of routinely using this technique even before the coronavirus pandemic, you should be impressed.

Why doesn't my dentist routinely place a rubber dam for procedures?

It's extremely common that one of the first good habits that a dentist falls out of after completing dental school is the habitual placement of a dental dam for applicable procedures.

It takes a few moments to place one, and at times, keeping one in place or establishing a completely dry work area can be a struggle. And, admittedly, for the most easily accessed teeth, or for very minor, simple or quick procedures, the same level of results are probably achieved whether one is placed or not.

What's different now, and why their usual protocol must be reevaluated, is that the COVID-19 virus exists.

Can a dental dam be used with all patients?

Generally, yes. Certainly, some difficulties do arise with some patients, like having a latex allergy or a condition where it's difficult for them to breathe through their nose. But there are alternative materials and techniques that are routinely used to overcome these types of obstacles.


 Page references sources: 

Heasley JM. Technique for Achieving General Field Isolation During Dental Procedures. Dentistry Today. January 2003.

Romero MF, et al. 10 Steps to Rubber Dam Isolation in Restorative Therapy. Decisions in Dentistry. November 2019.

Sabino-Silva R, et al. Coronavirus COVID-19 impacts to dentistry and potential salivary diagnosis. Clin. Oral Invest. February 2020.

Szymanska J. Dental bioaerosol as an occupational hazard in a dentist's workplace. Ann. Agric. Environ. Med. Vol. 14, No. 2. 2007

Turkistani KA. Precautions and recommendations for orthodontic settings during the COVID-19 outbreak: A review. Am. J. Orthod. Dentofacial Orthop. May 13, 2020.

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