Dogs and cats have strong jaws that can cause varying degrees of damage to their teeth if they chew on the wrong things. This month’s and next month’s columns will review the variety of manifestations of self-trauma to small animal teeth.

Abrasion and attrition

The American Veterinary Dental College’s (AVDC) Nomenclature Committee defines abrasion as “tooth wear caused by contact of a tooth with a non-dental object.” In comparison, attrition is defined as “tooth wear caused by contact of a tooth with another tooth.”¹

Abrasion occurs from chewing on hard objects, such as bones and rocks, but it can just as easily happen by chewing on something soft, such as a tennis ball. As the tennis ball gets tossed around the yard, its surface picks up dirt and dust. This debris acts like sandpaper along the surface of the tooth, resulting in a characteristic wear pattern of multiple teeth (Figure 1A).

Abrasion may not require any treatment, but sometimes it can occur fast enough to result in exposed dentinal tubules and even exposed dental pulp. Brown discoloration of the abraded tooth crown may be due to either tertiary dentin deposition as a response to wear, or it may indicate pulp exposure. Move a sharp-tipped explorer over the surface of the abraded tooth to see if there is any evidence of pulp exposure. Even if no pulp exposure is seen, it is advisable to monitor abraded teeth radiographically since they can still develop endodontic disease or undergo root replacement resorption (Figure 1B). Attrition most commonly occurs due to either malocclusion that results in tooth-to-tooth contact or grinding of teeth (less common in our patients than in humans).

Pulpitis and pulp necrosis

Pulpitis is inflammation of the pulp, which occurs most commonly due to blunt trauma to a tooth. This trauma may be caused by the patient bumping the tooth or chewing down hard on something in a way that traumatizes the tooth without causing a fracture of the crown or root.

The discoloration seen with pulpitis or pulp necrosis is due to trauma to blood vessels within the pulp chamber of the tooth, which results in leakage of red blood cells. The breakdown products of red blood cells diffuse from the pulp into dentinal tubules beneath the enamel, imparting a discoloration to the crown (Figure 2). Over time, the discoloration progresses from a pink/purple color to gray/brown.

Pulpitis can be a painful condition because inflammation in the tooth is similar to that in the brain. Swelling within an enclosed structure results in damage to the remaining soft tissue within that structure. Depending on the stage of the disease, the nerve fibers within the pulp may transmit sharp pain stimuli, or once the pulp within the tooth is dead, pain may subside until periapical disease develops.

I recommend treating the intrinsically discolored tooth, given dogs just will not tell us when they have a painful pulpitis, and subsequently necrotic teeth are at risk of infection.

A landmark study published in 2001 showed that, of 64 discolored teeth that were explored via pulpotomy, 59 had gross evidence of partial or complete pulp necrosis (92 percent).² Forty-two percent of discolored teeth evaluated radiographically in this study had no radiographic evidence of endodontic disease, suggesting radiographic signs lag behind pulp inflammation
and necrosis.²

A more recent histologic study of 102 intrinsically discolored teeth showed 87.5 percent of teeth were histologically nonvital, whereas only 42.3 percent of these showed histologic evidence of endodontic or periodontal inflammation.

Pulp necrosis was commonly seen in intrinsically discolored teeth, but pulp inflammation (pulpitis) was only seen in 12.4 percent of cases.³

Two options exist for treating pulpitis/pulp necrosis: extraction or endodontic therapy. These teeth are often great candidates for the latter since they are often functionally important teeth, and the crowns are often intact.

Endodontic therapy is accomplished after taking dental radiographs to ensure no occult fractures of the crown or root. Access sites are created to allow for cleaning of the pulp chamber (within the crown) and root canal (within the root). The pulp is removed, the canal is irrigated, and instruments are used to mechanically disinfect, shape, and fill the canal.

The filling material in the root canal acts like a cork in a wine bottle, preventing percolation of fluids and bacteria into the periapical bone surrounding the root. The final critical step of root canal therapy is placing a restoration that will seal the access sites to prevent microleakage. Whether or not to place a prosthetic crown over the endodontically treated tooth is decided on a case-by-case basis, depending on chewing habits and suspected likelihood of future tooth fracture.

Left untreated, periapical bone loss and root resorption can occur even in a closed system, either due to inflammation or infection. Although a tooth with pulp exposure provides a direct highway for oral bacteria to migrate to the periapical bone, a process called anachoresis (hematogenous spread of bacteria and colonization of a compromised site) may result in periapical infection even in nonvital teeth that do not have pulp exposure.

Next month’s column will address other forms of self-trauma, including tooth fractures and avulsions. Keep in mind, many of these types of trauma are avoidable when the natural chewing behavior is channeled to the correct chew items. Suggest to clients they avoid indestructible chew toys. Pet owners often need to choose which of the two will be destroyed: the chew item or the tooth. Help patients “chews” wisely!

John Lewis, VMD, DAVDC, FF-OMFS, practices and teaches at Veterinary Dentistry Specialists and Silo Academy Education Center, both located in Chadds Ford, Pa.

References

1. https://avdc.org/avdc-nomenclature
2. Hale FA. Localized intrinsic staining of teeth due to pulpitis and pulp necrosis in dogs. J Vet Dent. 2001;18(1):14-20. https://pubmed.ncbi.nlm.nih.gov/11968908
3. Feigin K, Bell C, Shope B, Henzel S, Snyder C. Analysis and Assessment of Pulp Vitality of 102 Intrinsically Stained Teeth in Dogs. J Vet Dent. 2022;39(1):21-33. https://pubmed.ncbi.nlm.nih.gov/34825611