Rubber Dam: Tooth isolation during root canal treatment.

- What is a rubber dam / dental dam? | What purpose does it serve? | How important is it to use one? | How is a dam placed? | What's it like to wear one? | Managing problems: Latex allergy, breathing difficulty.

What is a rubber dam?

When used as a part of root canal treatment ...

A tooth with a rubber dam in place.

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

  • A rubber dam (also referred to as a "dental dam") is a sheet of latex that the tooth being treated sticks through.
  • With most applications, the dam is held in position via the use of a "rubber dam clamp" that firmly grasps around the tooth.
  • The dam is used for tooth "isolation," meaning it acts as a barrier that partitions the tooth being treated from the wet, contaminate-laden environment of your mouth.

The following diagram illustrates the cross section of a tooth with a rubber dam in place.

Tooth with dental dam in place.

Diagram of a tooth with rubber dam in place.
  • The dam is represented by the green line.

    (Note that in this application just a single tooth, a molar that will receive root canal treatment, sticks through the dam.)

  • A rubber dam clamp has been placed on the molar (the grey object in our illustration) and it holds the dam in place low on the tooth (down around its gum line).
  • Notice how the dam isolates the upper portion of the tooth from the mouth environment.

    a) Items underneath the dam (other teeth, the tongue and other mouth structures) lie in a saliva-laden, bacteria-filled environment.

    b) The part of the tooth the dentist works with is situated above the confines of the dam. And after being washed and dried, lies in a comparatively contaminate-free environment.

What purpose does a rubber dam serve during root canal treatment?

Dental dams are placed for two general reasons. One involves benefits it provides for your dentist as they perform your tooth's work. The other is the protection and advantages it provides for you, the root canal patient.

a) Tooth isolation is an important part of the root canal process.

1) A dam aids in maintaining an aseptic operating field.

We've already hinted that a primary purpose for placing a rubber dam is to keep oral contaminates away from the tooth that a dentist is treating.

Tooth with access cavity and rubber dam.
  • One of the main goals of root canal therapy is cleaning out the interior of the tooth. Placing a dam helps to insure that contaminates from the mouth (saliva, debris, bacteria) aren't allowed to enter the tooth as the dentist proceeds with this work.
  • 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 oral fluids to enter into the tooth via the access cavity created for its work.
2) Dam placement enhances procedure efficiency.

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

  • Because it retracts the patient's cheeks and keeps their tongue at bay, the dentist has improve visibility and less encumbered access to the operating field.
  • The dry field that a dam provides means that activities related to moisture control (like suctioning) are significantly reduced.
  • Procedure efficiency is enhanced because interruptions and conversation originating with the patient are minimized.

b) A rubber dam provides patient protection.

Performing the root canal procedure involves the use of a number of small instruments (such as root canal files) and several types of medicaments (like the solutions used to periodically flush the interior of the tooth out).

Without a dental dam in place, if any of these are lost in the patient's mouth the episode may result in tissue irritation, harm or even damage. This is especially true if the item is aspirated (inhaled) or swallowed.

Of the two, complications involving liquids is the more common. Admittedly, even when a dam is not placed, aspiration or ingestion of root canal instruments is a very rare event (Ahmad 2009). [reference sources]

How important is the use of a dental dam during endodontic therapy?

There is no question that in regard to the dental community as a whole, and in terms of the training your dentist received in dental school, that the importance of using a rubber dam while performing root canal treatment is paramount.

  • Its use is considered the "standard of care," both in the USA and internationally (Gilbert 2015).
  • Its placement is recommended by the European Society of Endodontology, American Association of Endodontists and the American Academy of Pediatric Dentistry. (Webber 2017, Ahmad 2009)
  • A paper by Gilbert (2015) states that the author is unaware of any "US dental school that does not require use of a rubber dam during root canal treatment."

a) How dental dam use affects root canal 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. (Performing treatment on patients that doesn't meet the current standard of care for that procedure.)

None the less, 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 (initial treatment, no retreatment cases were included). The work had been performed by actual practicing dentists and endodontists in a variety of practice settings.

  • Case success was simply measured by the fact that the database did not note that the tooth had been extracted. (The presumption for extraction would be because 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 showed 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 were then retreated. It was determined that treatment success was significantly better for those cases where isolation with rubber dam was used.

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

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 Ahmad [2009].)

Other effects on treatment outcome.

As mentioned above, when a dam is not used during treatment 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 frequently use less effective irrigating solutions (which is likely to affect case success) as a way of minimizing immediate complications if an accident occurs. (Ahmad 2009)

b) Our comments about dentists 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 outcome. 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 any patient who assumes that their tooth's procedure is a suitable exception to a well established guideline, and also accepts that the substitute method of isolation used for their treatment is as predictable as the use of a rubber dam, is naive at best.

It seems more likely the case that the dentist 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.

c) Disregard for patient well-being.

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

As discussed above, 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.

FAQ's about dental dams.

How does a dentist place a dental dam?

Placing a rubber dam around a tooth for its root canal treatment is a simple enough process, although getting everything set exactly right may prove to be a bit of a wrestling match for the dentist (hence one of the reasons why some don't place them).

A tooth with a rubber dam in place.

A rubber dam clamp and frame in use.

  • The dentist will start by taking a sheet of dam material (usually a 6 X 6 inch square of latex) and punching a single hole in the area near its center.
  • They'll then stretch the hole over the tooth receiving treatment. (Just it alone will stick out above 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 slipping off the tooth.)
  • The dentist will then stretch out the corners of the sheet and snag them on a rubber dam frame (see picture) so they are out of the way and the dentist has good access and visibility.

A rubber dam clamp.

A rubber dam clamp.

What is a rubber dam clamp?

A rubber dam clamp is actually a metal spring.

  • The dentist will spread open the clamp with special pliers so it can be positioned on its tooth.
  • As the tension on the clamp is relaxed, it's prongs will close together until they find a firm resting point on the sides 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 dam that lies underneath, 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. The one chosen for your case will simply depend on what kind of tooth is being worked on and the circumstances associated with it.

Our picture above shows a clamp designed for use with lower molars. Other photos on this page show clamps designed for used 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 your numbness you may feel the pressure of the clamp grasping your tooth.

Using our referral links for purchases supports this website at no additional cost to you. It's sincerely appreciated if you do.
Shop either ▶ Amazon related products below on this page, or else for any items on ▶ or ▶

What if you're allergic to latex?

Despite the name "rubber dam," the elastic material most frequently use for dental dams is latex.

Some people have an allergy to latex and if you do dams made of other materials (nitrile, polyisoprene, polyethylene or polyvinyl chloride) can be (and are routinely) used.

Additionally, all types of dam materials can be purchased in "powder free" form if that agent (usually corn starch) is the allergen in your case.

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, you're on the other. That's nice.
  • That separation means that you really don't have to offer much cooperation during your procedure and instead you can just relax. 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 your teeth and gums have been numbed it's normal and expected that you may still may feel the pressure of the clamp on your tooth. Don't confuse that with pain because feeling either is not related.
  • 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.

In regard to the use of a rubber dam during root canal appointments, papers by Madarati (2016) and Ahmad (2009) 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.

What if wearing a dental dam interferes with your breathing?

A rubber dam usually does cover over all of a person's mouth. And for those people who have trouble breathing through their nose (and therefore must breathe through their mouth) this can present problems.

Fortunately, there's a easy solution. The dentist can simply cut a hole through the dam in an out-of-the-way 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.