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?

A tooth with a rubber dam in place.

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

When used in conjunction with endodontic procedures ...

  • A rubber dam (also referred to as a "dental dam") is a sheet of latex that the tooth being treated sticks through.

    (In most applications, the dam is held in position on its tooth via the use of a metal "rubber dam clamp." See picture.)

  • The dam provides tooth "isolation," meaning it acts as a barrier that partitions the tooth being treated from the wet, contaminate-laden environment of your mouth.
Diagram - How a dental dam works.

The following illustration (a cross-sectional view of a patient's jaw and teeth) should make the basic premise of using a rubber dam clear.

Tooth with dental dam in place.

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

    Note: In this application just a single tooth, a 2nd molar, will receive root canal therapy. Therefore, it alone sticks through the dam.

  • A rubber dam clamp has been placed on the 2nd 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 (the part of the tooth through which the dentist will do their work) from the rest of the oral 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 level of the dam. And after being washed and dried, lies in a comparatively contaminate-free environment.


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

A dental dam offers two general areas of service.

a) One involves benefits it can provide for your dentist as they perform your tooth's work.

b) The other has to do with the protection and advantages it provides for you, the root canal patient.

a) Benefits for your dentist and procedure.

A dam aids in maintaining an aseptic operating field.

One of the main goals of root canal therapy is cleaning 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.

Tooth with access cavity and rubber dam.

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 that's been created for its work.

Dam placement enhances procedural 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 needed for moisture control (like suctioning) are significantly reduced.
  • Procedure efficiency is enhanced because interruption/conversation originating from the patient are minimized.

b) Benefits for the patient.

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 out the interior of the tooth).

Without a dental dam in place, if any of these are lost in the patient's mouth, the episode that follows 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)

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

There is no question that in regard to: 1) The opinion of the dental community as a whole and 2) 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).
  • Its placement is recommended by the European Society of Endodontology, American Association of Endodontists 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."

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 endodontic therapy for patient's without the use of a rubber dam, which is a breach of the standard of care that a dentist is expected to provide.)

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 (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 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 information cited in a paper by Ahmad [2009] - linked above.)

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 is likely to affect case success) as a way of minimizing immediate complications if an accident occurs. (Ahmad - linked above.)

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 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.

c) 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, 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 on a tooth for its root canal procedure is a simple enough process, although getting everything set exactly right can 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 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 rubber dam frame (the light brown object in our picture) so they are held 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 in reality a metal spring.

  • 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, it's 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.

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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.

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.

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 with future visits.

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 a 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.

 

Last revision/review: 12/20/2018 - Revision with content added.

 
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