How to save a canine tooth

What you need to know

I recently had the rare opportunity to replace an avulsed tooth. A 4-year-old Irish setter got into a scuffle with another dog. The owner noted bleeding from the mouth and an intact canine tooth on the floor. The left maxillary canine tooth (tooth 204) appeared to be completely avulsed from its alveolus (Figures 1-A, 1-B).

A diseased tooth lost to severe periodontal disease is not a candidate for replantation, but a functionally important, nonfractured tooth that is avulsed due to trauma may be worth considering for replantation.

Left to right: Figure 1-A. A 4-year-old Irish setter presents with an avulsed left maxillary canine tooth; figure 1-B. Radiograph of alveolus before tooth replacement.

Some Fundamentals

First, a bit of terminology.

Avulsion refers to a tooth that is completely disarticulated from its socket and is found outside the mouth. Luxation describes a tooth that has moved significantly from its socket but still has some gingival attachments. Subluxation describes clinically imperceptible, but radiographically perceptible, movement of a tooth within its alveolus.

When a tooth becomes avulsed, the tooth and patient need to get to a veterinary dentist as soon as possible. This is one of the rare true dental emergencies.

Ideally, the tooth should be replanted within 15 to 20 minutes of the avulsion. If extraoral dry time was 20 to 60 minutes, some periodontal ligament cells may be vital. If extraoral dry time was greater than 60 minutes, all periodontal ligament cells have likely died and re-plantation has a poor prognosis due to root resorption over time.

Immerse the Tooth

Since the ideal replantation time frame is unlikely to be accomplished, instructing the owner to place the tooth in a proper liquid is important.

Water is not a good option because it will kill periodontal ligament cells. Milk is easily accessible and provides up to six hours of survival time for periodontal ligament cells. The best liquid to use with an avulsed tooth is Hank’s Balanced Salt Solution, which may provide 24 hours of cell survival.

The alveolus of the tooth and the root surface should not be curetted because this will remove remaining periodontal ligament cells. The alveolus can be lavaged with Lactated Ringer’s solution or a diluted (0.05 to 0.1 mg/ml) doxycycline solution, and a similar solution may be used to rinse off the tooth root before replantation.

Antibiotic therapy is warranted immediately after avulsion and is continued for about two weeks postoperatively.

Step by Step

Figure 1-C. Tooth is replanted into the alveolus.

The tooth is replaced into its alveolus (Figure 1-C), lacerated soft tissues are sutured and a flexible or semirigid splint is applied. In the Irish setter’s case, the splint was a figure-of-eight wire held close to the tooth with a few blebs of light-cured dental composite. The twisted wire was bent toward the lateral surface of the tooth and covered with composite to prevent any sharp wire edges from cutting the tongue and soft tissues (Figures 2-A, 2-B).

Left to right: Figure 2-A. Tooth is stabilized and sharp wire is covered with a small amount of flowable dental composite; figure 2-B. Radiograph of figure-of-eight wire placement.

The endodontic blood supply to an avulsed tooth has been severed, so root canal therapy is necessary, which may be started at the time of replantation but not at the expense of reattachment. During a root canal, it is best to avoid filing the canal, thus minimizing any jarring of the newly replaced tooth.

Figure 2-C. After replacement of the tooth, a semirigid figure-of-eight wire is placed and the nonvital pulp is removed through an access site at the gingival margin.

Operating on the Irish setter, I opened the canal with a small access site at the gingival margin, removed the pulp and placed calcium hydroxide paste in the canal. This was in preparation for a complete obturation in the coming weeks once the periodontal ligament had a chance to reattach to the tooth (Figure 2-C).

Next Steps

Figure 3-A. Photograph of previously avulsed canine tooth four months after replacement.

When should the splint be removed? Ideally after four weeks, and at this time the root canal therapy can be finished (Figure 3-A).

The most likely complication of replanting an avulsed tooth is dentoalveolar ankylosis, or bony fusion between the tooth and alveolar bone. When ankylosis occurs, root replacement resorption follows.

Figure 3-B. Radiograph taken four months after replacement of avulsed canine tooth. Some evidence of dentoalveolar ankylosis is seen radiographically.

Loss of normal periodontal ligament structure results in loss of the normal “shock absorber” of the tooth and loss of the normal soft tissue barrier that prevents replacement of the tooth with newly remodeled bone.

Replanted teeth should be radiographically evaluated (Figure 3-B) at least once yearly to assess for evidence of root replacement resorption.

Recommended Reading

  1. Andersson L, Andreasen JO, Day P, Heithersay G, Trope M, Diangelis AJ, Kenny DJ, Sigurdsson A, Bourguignon C, Flores MT, Hicks ML, Lenzi AR, Malmgren B, Moule AJ, Tsukiboshi M; International Association of Dental Traumatology. International Association of Dental Traumatology Guidelines for the Management of Traumatic Dental Injuries.
  2. “Avulsion of Permanent Teeth.” Dent Traumatology 2012; 28(2): 88-96.
  3. Reiter AM, Lewis JR (Syring R, Beal M, Drobatz K, eds). “Trauma-Associated Musculoskeletal Injuries of the Head.” Trauma Management in the Dog and Cat. Oxford, UK: Wiley Blackwell. 2011; 255-278.

Dr. John Lewis practices veterinary dentistry and oral surgery at NorthStar Vets in Robbins-ville, N.J. Columnists’ opinions do not necessarily reflect those of Veterinary Practice News.

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