Emergency Treatment of Avulsed Teeth

More than five million teeth are knocked out (avulsed) in the United States each year, many of them during automobile accidents, sporting events like football, basketball and hockey, or work-related incidents.1 All of these teeth have the potential to be replanted and saved; however, for replanting to be successful in the long term, the teeth must be treated properly. Even teeth that have been out of the mouth for several days can be saved. Therefore, EMS providers should be prepared to institute optimum treatment for knocked-out teeth.

There have been great advances in the field of dental traumatology. Treatment for knocked-out teeth has progressed from a success rate of 10% to 90%; however, this success rate can only be achieved with institution of optimum care.2,3 This article reviews the basic philosophy for treatment of knocked-out teeth and provides the newest treatment regimens.

Basic Philosophy

Every tooth is connected to its surrounding bone by the periodontal ligament, through which teeth receive nourishment. When a tooth is knocked out, this ligament is stretched and splits in half: Half stays on the tooth root and half on the socket wall. If these two halves can be kept alive, the tooth can be replanted, the ligament halves will reattach and the tooth will remain vital. Since the half that stays on the socket wall remains connected to the bone’s blood supply, it is naturally kept alive (see Figure 1). However, the ligament cells that remain on the tooth’s root must be artificially maintained and protected from two potentially destructive processes: cell crushing and loss of normal cell metabolism. All treatment between the time of the accident and the ultimate replantation must focus on preventing these two possibilities.

Preventing Cell Crushing

When teeth are avulsed, they end up on an artificial surface—the floor, the ground or material like carpeting. If the surface is hard, the tooth root cells will receive trauma. Since the cells remaining on the tooth root are delicate, additional trauma to the tooth root cells must be avoided to prevent more root cell crushing. This damage can occur while picking the tooth up and during transportation to a dentist.

When picking up a tooth, grasp it by the enamel on the crown, as finger pressure on the root cells will cause cell crushing. Do not attempt to clean off any debris. At the very least, debris should be washed off gently with a physiologic saline. Even with saline, avoid “scrubbing.” When placed in a physiologic solution, gently agitate the tooth to permit cleansing of the root, taking care to not bump the tooth root against any hard surface like glass, plastic or even cardboard.

For the same reasons, the method for transporting the knocked-out teeth must be carefully selected. Placing knocked-out teeth in vehicles like tissues and handkerchiefs can damage the teeth. Placing them in glass or cardboard containers care are also potentially damaging to the cells. In addition to the potential damage that the hard surface can cause, glass containers have the added possibility of breakage or leakage of the physiologic storage fluid. If the glass container does not have a tightly fitting top, the physiologic solution can spill out during transportation and the teeth can fall on the floor.

The type of container in which the teeth are stored has an additional potential root cell-crushing possibility. When the knocked-out teeth arrive for replantation, the dentist is faced with the difficult task of removing them from the container. If the tooth was retrieved from a muddy or dirty accident site, such as a grass field or sand, the solution in which it is transported will become murky and opaque, making it difficult for the dentist to see. The dentist should also touch the tooth by the crown only. If he can’t clearly see the tooth and has to feel blindly for it with his fingers or dental forceps, he may inadvertently crush the root cells. If the knocked-out teeth are placed in a carton of milk, for example, there would be no other recourse for retrieving them except by spilling out the milk. Catching the teeth with latex-gloved hands while spilling the liquid is challenging.

Maintaining Normal Cell Metabolism

Normally, metabolizing tooth root cells have an osmolality (concentration) of 280–300 mOs and a pH of 7.2. When there is an uninterrupted blood supply, all of the metabolites and glucose that the cells require are provided. When the tooth is knocked out, however, the normal blood supply is cut off and, within 15 minutes, most of the stored metabolites have been depleted and the cells begin to die. Within one to two hours, enough cells have died to cause the body to reject the tooth. Rejection of the replanted tooth is through a process called “replacement root resorption.” During this process, the root cells root resorption.” During this process, the root cells become necrotic and are viewed by the surrounding bone as “not-self.” As a result, the body’s immunologic mechanism attempts to remove the necrotic “not-self” and literally eats away the tooth root. It is a slow but painless process that is sometimes not observed on x-ray for years. Once this process starts, it is irreversible, and the tooth will eventually fall out. It is particularly problematic in growing children because the replacement resorption (also termed ankylosis) impedes normal jaw growth.

Research has shown that the critical factor for reduction of replacement resorption following replantation of avulsed teeth is maintenance of normal cell physiology and metabolism.4 In order to maintain this normalcy, the environment in which the teeth are stored must supply the optimum osmolality, cell nutrients and pH.

Storage Media

There are many storage media available for knocked-out teeth, including water, ice, saliva, physiologic saline, milk and pH-balanced cell-preserving fluids.

Water and ice, although appealing to common sense, have actually been shown to damage tooth root cells.5 The reason for this is that the osmolality (concentration) and pH of water and ice are low. When a knocked-out tooth is placed in water, the cells attempt to equalize with the surrounding environment and burst.

Placing the tooth in the saliva under the accident victim’s tongue has been recommended; however, saliva as a storage medium is twice as problematic. Its low osmolality causes bursting, and the normal flora of microorganisms in saliva severely infects the tooth root. When the tooth is replanted, not only will the cells be necrotic, they will also infect the bone socket.

Physiologic saline has a fairly compatible osmolality and will not cause cell structure swelling, but it lacks the metabolites and glucose necessary for maintenance of normal cell metabolism.

Milk has been also recommended as a storage medium for avulsed teeth, because it has a compatible osmolality and it is thought to be readily available. However, like physiologic saline, it lacks the necessary metabolites and glucose for normal cell physiology.6 In addition, milk is not usually readily available in an ambulance. If sour milk is used, it will cause tooth root cell damage. Powdered milk and nonrefrigerated milk have also been tested and, due to the nonavailability of metabolites, did not show good success.

The most optimum storage media have proved to be pH-balanced cell-preserving solutions. The best known and most extensively tested is Hank’s Balanced Solution (HBS), which has all of the metabolites like Ca, P04, K+ and glucose that are necessary to maintain normal cell metabolism for long periods of time. HBS has been extensively tested in dental and medical research for the past 20 years.5

This research shows that 90% of cells stored in HBS for 24 hours maintain their normal viability; 70% is maintained after four days.

HBS also has the capability to reconstitute lost cell metabolites. Since a cell that has been cut off from its blood supply depletes its stored metabolites after 15 minutes, a tooth that has been extra-oral for one hour has 45 minutes fewer vital cells to reconnect with the bone ligament cells. This tooth has a significantly greater possibility of root damage.

Dental research has shown that the amount of root damage can be reduced by soaking the teeth in an HBS for 30 minutes prior to replantation, with teeth showing 50% less root damage following replantation.7 It has also been shown that keeping the teeth cold while in the HBS does not affect success. HBS is now recommended for use by all daycare centers in the state of Ohio.

EMS Treatment

Although some dentists advise that the best treatment for an avulsed tooth is immediate replantation, a variety of reasons make this difficult for EMTs. First, the accident victim may have other more serious injuries that require immediate attention. Second, as already mentioned, the teeth are often covered with debris that must be washed (not scrubbed) off with a physiological solution. If multiple teeth are knocked out, EMTs won’t know into which socket an individual tooth belongs. The patient may have other injuries, such as a severely lacerated lip or gum that prevent easy visualization of the socket. Finally, the patient may be in severe pain and may not allow replantation of the teeth into the sockets.

For all of the above reasons, EMS should have an optimum storage device available in every ambulance. The device should be a shatterproof container with a tightly fitting top and should be large enough to hold 1–8 teeth, with a non-abrading, cushioning apparatus that will prevent the teeth from bumping into each other or striking the sides of the container and permit nontraumatic removal of the teeth by the dentist.

There is a commercially available product—Save-A-Tooth—that fulfills all of the requirements for safe storage and preservation of knocked-out teeth and is accepted by the American Dental Association for this use.8 This product contains a removable basket and net that suspends knocked-out teeth to allow for debridement and atraumatic removal. It has a shelf life of two years and needs no refrigeration.

Having optimum storage devices available for knocked-out tooth storage will prepare EMTs for every contingency and will provide dentists with the best possible condition for the replantation procedure. The chain of events in avulsion replantation is only as strong as its weakest link. By providing a well-preserved knocked-out tooth to the dentist, EMTs can support every patient with the strongest link possible.

References

1. Krasner P, Rankow H. New philosophy for the treatment of avulsed teeth. Oral Surg Oral Med Oral Pathol 79:616–623, 1995.
2. Lenstrup K, Skieller V. A follow-up study of teeth replanted after accidental loss. Acta Odontol Scand 17:503–509, 1959.
3. Krasner P, Person P. Preserving avulsed teeth for replantation. J Am Dent Assoc 123:80–88, 1992.
4. Pathways of the Pulp, 8th Ed. Cohen S, Burns R. eds. Trope M. Traumatic Injuries, Chapt. 16, p 636–637. St. Louis, MO: Mosby, 2002.
5. Blomlof L. Milk and saliva as possible storage media for traumatically exarticulated teeth prior to replantation. Swed Dent J Suppl. 8, 1981.
6. Gamsen EK, Dumsha TC, Sydiskis R, et al. The effect of dry-storing time on periodontal ligament cell vitality. J Endodon 18:189, 1992.
7. Matsson L, Andreasen JO, Cvek M, Granath L-E. Ankylosis of experimentally reimplanted teeth related to extra-alveolar period and storage environment. Pediatr Dent 4:327–329, 1982.
8. American Dental Association Council on Acceptance.