What is a dental dam (rubber dam) and why is it so important for root canal treatment?

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What is a rubber dam?

When used in conjunction with endodontic procedures …

A rubber dam, also referred to as a “dental dam”, is a sheet of latex that a tooth receiving conventional root canal therapy is positioned (poked) through.

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

The dam creates tooth “isolation,” meaning it acts as a barrier that partitions the tooth being treated from the wet, contaminate-laden environment of your mouth.

A tooth with a dental dam in place.

What services does a rubber dam provide during root canal treatment?

It assists your dentist in performing your tooth’s endodontic treatment more efficiently and effectively.

Placing a dam offers protection and convience for you the dental patient.

a) How a rubber dam benefits your dentist and procedure.

1) Placing a dam is important in maintaining an aseptic operating field.

One of the main goals of root canal therapy is cleaning and disinfecting your tooth’s root canal system. Why? | How?

Dental dam isolation.

• By placing a dental dam, a dentist ensures that contaminants from your mouth (saliva, debris, bacteria) can’t seep into your tooth while its work is being performed.
• In our picture, it’s easy enough to imagine that if a dental dam wasn’t in place it would be a simple matter for indigenous oral bacteria and fluids (meaning contaminants originating from your own mouth) to enter into the tooth via the access cavity that’s been created for its work.

2) Dam placement enhances procedural efficiency.

The tooth isolation that a rubber dam provides creates some procedural advantages for the dentist when performing your work.

• Because it retracts the patient’s lips and cheeks and keeps their tongue at bay, the dentist has improved visibility and less encumbered access to the operating field.
• The dry field that a dam provides means that activities needed for moisture control (like suctioning) are significantly reduced.
• Procedure efficiency is enhanced because interruption/conversation originating from the patient is minimized.

b) How a rubber dam benefits you the dental patient.

1) A dam helps to ensure patient safety and protection.

When performing your root canal procedure …

• Your dentist will use of a series of small instruments (root canal files What are they?) inside your tooth.
• They’ll also use one or more kinds of irrigating solutions. (Liquids used to periodically flush out the interior of your tooth. Why? | How?)

Because a dental dam creates a physical barrier, if any instruments are dropped or irrigants leak from your tooth they are easily and safely retrieved.

In comparison, without a dam in place, significant risk exists for soft tissue irritation, harm, or even damage. This is especially true if the item is aspirated (inhaled into your pulmonary system) or swallowed (entered into your digestive system).

▲ Section references – Ahmad

2) Other benefits for the patient.

While wearing a dental dam may be different from what you’ve experienced before. You may find that you quite like the whole experience.

Once a rubber dam is in place, it will seem like you have your side of things and your tooth and its treatment are all on the other. Your face will be exposed to less mist and splatter. And since liquids from your procedure can’t enter your mouth, you won’t have as much inclination to constantly swallow. Overall, you’ll probably find your procedure to be a more comfortable experience than many other kinds of dental treatments you’ve had.

Rubber dam benefits associated with the COVID-19 pandemic.

An issue that’s become a major concern since we originally created this page is the fact that the use of a rubber dam during a person’s root canal procedure is a major aid in helping to prevent the spread of airborne microorganisms (like the COVID-19 virus) from infected patients. It does so by keeping patient oral fluids (saliva) from being included in the aerosol (mist, splatter) that’s created as their treatment is performed.

And while the use of a rubber dam can be implemented with a variety of other dental procedures too, the fact that its use is unequivocally considered to be the standard of care required when non-surgical (conventional) root canal treatment is performed (see next section) means that having endodontic therapy may arguably be the least likely dental procedure to spread the virus.

How important is using a dental dam during endodontic therapy?

There’s nothing more important.

There is no question that the world’s dental community as a whole considers the use of a rubber dam when performing nonsurgical endodontic treatment to be paramount.

• Placing a dam is considered the required “standard of care” for endodontic treatment, both in the USA and internationally (Gilbert).
• Its placement is recommended by the European Society of Endodontology, American Association of Endodontists (AAE), and the American Academy of Pediatric Dentistry. (Webber, Ahmad)
• The same paper by Gilbert cited above states that the author is unaware of any “US dental school that does not require use of a rubber dam during root canal treatment.”

Note: Nonsurgical or conventional endodontic treatment refers to the method of performing a tooth’s procedure through an opening drilled through its crown (as shown in the pictures on this page). This is the most commonly used method for root canal work.

▲ Section references – Gilbert, Webber, Ahmad

FYI: If you’d like more information about how important the use of a rubber dam is during root canal treatment, check out this section of our page: How dental dam usage benefits endodontic treatment success. Study findings.

How does a dentist place a dental dam?

Placing a rubber dam on a tooth for its root canal procedure is simple enough, although getting everything set exactly right can be a little time-consuming and prove to be a bit of a wrestling match for the dentist. (Hence one reason why some don’t place one.)

A rubber dam clamp and frame in use.

• The dentist will start by selecting a sheet of dam material (usually a 6 X 6-inch square of latex). They’ll then punch a single hole near its center.
• The hole will be stretched over the tooth slated for treatment. (Just it alone will stick out above the surface of the dam.)
• A rubber dam clamp (see next section) will then be placed on the tooth, so to hold the dam in place. (It keeps it from pulling off the tooth.)
• The dentist will then stretch out the corners of the sheet and snag them on a plastic or metal frame (the light brown object in our picture) so they are held out of the way and the dentist has good access and visibility.

What is a rubber dam clamp?

In reality, a rubber dam clamp is a metal spring.

A rubber dam clamp.

• The dentist will spread open the clamp (spring) with special pliers so it can be positioned on its tooth.
• As the tension on the clamp is relaxed, its prongs will close together until they find a firm resting point on the surface of the tooth.
• Once positioned, a clamp’s steady grasp acts as an anchor point that can withstand the pressure exerted by the stretched rubber (latex) sheet, thus holding everything in place.

Your dentist will have an assortment of dam clamps, each having a unique design specially created for a specific type of tooth. (Our picture above shows a clamp designed for use with lower molars. Other photos on this page show clamps in use with other types of teeth.)

Note: The local anesthetics used in dentistry typically aren’t effective in conking out the sensation of pressure. For that reason, despite being numb you may feel the pressure of the clamp grasping your tooth.

Miscellaneous FAQs about rubber dams.

1) What if you’re allergic to latex?

Despite the name “rubber dam,” the sheet of elastic material actually used is usually latex.

Some people have an allergy to latex. If so, a sheet of some other material (nitrile, polyisoprene, polyethylene, or polyvinyl chloride) can be used.

Additionally, all types of dam materials can be purchased in powder-free form, if that agent (usually corn starch) is an allergen for you.

2) How uncomfortable is wearing a dental dam?

We’re under the impression that patients generally find the use of a rubber dam at least tolerable, if not the preferred experience.

• When one is placed, your tooth and dentist are on one side of it, and you’re on the other. A lot of patients like this configuration.
• That separation means that you really don’t have to offer much cooperation during your procedure. Instead, you can just relax. And in fact, some people actually fall asleep.

  Of course, you’ll still need to stay open for your dentist. However, if that proves to be much of a problem, just ask to use a “bite block” (a rubber mouth prop).

• As mentioned above, even though you’ll have been numbed up for your procedure, it’s normal and expected that you may still feel the pressure of the rubber dam clamp grasping your tooth.
• The contact between the dam and your face may create a sweaty situation. As a solution, a dam napkin (having the texture of a paper towel) can be placed in between.

Research findings.

In regard to the use of a rubber dam during root canal appointments, papers by Madarati and Ahmad both state that reporting from surveys has shown that patients have no objection to the use of a dental dam, and respond with a preference for its use during future visits.

▲ Section references – Madarati, Ahmad

3) What if wearing a dental dam interferes with your breathing?

A rubber dam usually covers all of a person’s mouth. And for those people who have trouble breathing through their nose (and therefore need to breathe through their mouth) this can present a problem.

Fortunately, there’s an easy solution. Your dentist can simply cut a hole through the dam in an out-of-the-way (off to the side) location. That way the benefits and advantages of using a dam are retained, and you’ll still be able to breathe through your mouth as needed.

4) A rubber dam clamp may cause minor post-op irritation.

Following your root canal appointment, once your numbness has worn off, you may find that the prongs of the rubber dam clamp used during your procedure have traumatized (bruised, cut) the gum tissue surrounding your tooth.

• This tenderness should just be minor and can be expected to disappear in a day or so.
• The use of a salt-water rinse may help to speed up healing. (1/2 teaspoon of salt to a cup of warm water. Rinse every three to four hours. Spit the rinse out.)

How dental dam use benefits root canal treatment success.

Previously on this page, we outlined some of the procedural advantages that a rubber dam provides. And one might assume that these benefits should translate into an improved success rate for teeth treated with one in place.

Research documenting this effect has been scarce, primarily because of the ethical dilemma that the design of such a study would create. (Clinicians performing endodontic therapy for patients without the use of a rubber dam, which is a breach of the standard of care that a dentist is expected to provide.)

Nonetheless, researchers have found ways to document the beneficial effect of dental dam usage:

Research study: Lin (2014)

This study evaluated a database of over 1/2 million teeth that had received root canal therapy (the work was initial treatment, no retreatment cases were included).

• The procedures were performed by both general dentists and endodontists (root canal specialists), in a variety of practice settings.
• Case success was simply measured by the fact that the database did not record that the tooth had been extracted. (The presumption for extraction would be that the tooth’s root canal therapy had failed.)
• On average, the teeth were followed over a 3.4-year time span.

Study findings.

Over this short duration, the survival probability (the probability of not being extracted) for the teeth whose root canal procedure was performed using a rubber dam was 90.3%. The survival of teeth treated without the benefit of a dam was 88.8%.

While seemingly a small difference, statistical analysis of the data determined that dam usage provided a significantly greater survival probability for teeth.

Research study: Van Nieuwenhuysen (1994)

This study evaluated 612 teeth whose initial root canal treatment had failed and was then retreated. It was determined that treatment success was significantly better for those cases where isolation with a rubber dam was implemented.

(This is a historic study to which we do not have access. Our reporting is based on a citation found in a 2009 paper by Ahmad.)

Research study: Abbott (1994)

This investigation evaluated 100 patients to determine what factors were most associated with continued pain after the initiation of root canal treatment.

“Lack of use of rubber dam” was the number one factor, and was observed in 87% of patients.

(This is a historic study to which we do not have access. Our reporting is based on a citation found in a 2009 paper by Ahmad.)

▲ Section references – Lin, Ahmad

Other effects on treatment outcome.

As mentioned above, when a dam is not used during treatment the solutions used to flush (irrigate) the interior of the tooth might be spilled into the mouth and/or swallowed, resulting in irritation or harm.

Studies have shown that dentists who do not place a dental dam tend to use less effective irrigating solutions (which will likely affect case success) as a way of minimizing immediate complications if an accident occurs.

▲ Section references – Ahmad

Our comments about dental practitioners who do not utilize a dental dam.

On average, it seems well justified to state that not using a rubber dam during root canal therapy compromises treatment outcomes. However, for any one tooth’s procedure, it’s possible to make the case that establishing tooth isolation via another method (like placing cotton rolls aside the tooth) could prove effective.

We think that any patient who assumes that their tooth’s procedure is an exception to a well-established guideline, and also accepts the premise that the alternative method of isolation used for their procedure is as predictable as the use of a rubber dam, is naive at best.

It seems more likely that the dentist who is providing their treatment has simply fallen into bad habits (we might add, completely contrary to the way they were trained in dental school). If your dentist doesn’t use a rubber dam during your root canal procedure, you should be asking questions.

Disregard for patient well-being.

Even accepting the case that effective tooth isolation might be maintained without the placement of a dam, a patient should note that this approach disregards concerns for their safety during their procedure.

As discussed above, the placement of a rubber dam prevents the possibility of swallowing or inhaling objects or medicaments used during the patient’s procedure. No other method of tooth isolation can provide this same level of insurance.

What’s next?

We have a lot more information about root canal treatment …