Usually considered a common feline condition, resorptive lesions are being diagnosed more frequently in dogs. This issue can cause significant pain for your dog and affect their overall health. Our team at Animal Dental Clinic would like to offer you some information on this problematic condition to help you protect your dog’s dentition.

What are resorptive lesions in dogs?

Odontoclasts are cells that typically function to assist normal tooth movement and resorb deciduous teeth, making room for permanent teeth to successfully erupt. When these cells malfunction, they can cause abnormal dental hard tissue resorption. This condition is different from dental caries (i.e., cavities or tooth decay), which occurs when acidic byproducts from bacteria cause the tooth enamel to break down. Large breed dogs and older dogs are most at risk for tooth resorption. Classifying the type and stage of tooth resorption is important to be able to treat the condition effectively.

How are resorptive lesions in dogs classified?

X-rays are needed to appropriately classify the type of resorptive lesion. The pulp, cementum, dentin, and enamel compose teeth. The pulp is surrounded by dentin, which is covered at the crown by enamel, and at the root by cementum. The periodontal ligament (PDL) attaches the tooth to the jawbone. The types of lesions are:

  • External surface resorption — Shallow cavities affect the cementum and dentin. Dogs usually do not show signs when affected by this type. Mild trauma is a common cause.
  • External replacement resorption — The PDL space gradually disappears as bone replaces the root tissues, and the tooth begins to fuse to the bone. Dogs affected by this type usually do not show signs. Injuries that cause PDL necrosis can result in external replacement resorption.
  • External inflammatory resorption — Inflammatory conditions can cause dental tissue and bone to be lost. Periodontal disease can lead to this resorption type.
  • External cervical root surface resorption — The tooth is affected by invasive resorption, for unknown reasons.
  • Internal surface resorption — An oval-shaped enlargement is seen in the root canal closer to the jawbone. Mild traumatic injury can cause this type of resorption.
  • Internal inflammatory resorption — An oval-shaped enlargement is seen in the root canal closer to the gumline. Inflammatory disease can cause this type of resorption.
  • Internal replacement resorption — Enlargement next to the root canal is observed. Root fractures and displacement injuries can cause this type of resorption.

How are resorptive lesions in dogs staged?

Resorptive lesions also can be staged to determine the severity. The five stages are:

  • Stage 1 — Mild dental hard tissue loss, which can involve cementum, or enamel and cementum.
  • Stage 2 — Moderate dental hard tissue loss. In addition to cementum and enamel loss, dentin is lost, but the damage does not extend to the pulp cavity.
  • Stage 3 — Deep dental hard tissue loss. Cementum, enamel, and dentin are lost. The damage extends to the pulp cavity, but the tooth remains stable.
  • Stage 4 — Extensive dental hard tissue loss. Cementum, enamel, and dentin are lost. The damage extends to the pulp cavity, and the tooth is no longer stable.
    • Stage 4a — The crown and root are equally affected.
    • Stage 4b — The crown is more severely affected than the root.
    • Stage 4c — The root is more severely affected than the crown.
  • Stage 5 — Few dental hard tissue remnants remain and are only visible on x-rays. The gingiva completely covers the resorbing root.

What are resorptive lesion signs in dogs?

Resorptive lesions can cause significant discomfort for your dog. Signs include:

  • Jaw spasms or “chattering” when painful lesions are touched
  • Increased salivation
  • Bleeding from the mouth
  • Difficulty or reluctance to eat
  • Pawing at the mouth
  • Lethargy
  • Bad breath

How are resorptive lesions treated in dogs?

When treating resorptive lesions in dogs, veterinary professionals have to consider the type, location, and stage of the defect, as well as the dog’s clinical condition. External and internal surface resorption are self-limiting processes and do not require treatment. Internal replacement resorption often can be monitored since the condition is typically not progressive. When inflammatory processes contribute, resolving the underlying disease is necessary to control the problem. Other types are treated using extraction or root canal therapy. The stage of the lesion also is considered when deciding on a treatment course. For stage 1 lesions, treatment is focused on preventing or slowing further erosion. Fluoride varnishes can be applied to desensitize the pulp, harden the enamel, and provide antibacterial action by reducing the enamel’s porosity. For all other stages, treatment usually entails root canal therapy, crown amputation, or extraction.

How are resorptive lesions prevented in dogs?

Not all resorptive lesions can be prevented, but ensuring your dog has routine oral examinations, dental x-rays, and professional dental cleanings will control inflammatory processes and will catch other conditions in their early stages before they cause your pet pain. 

All dogs should be seen once yearly for routine dental evaluations, and senior dogs should be examined every six months to ensure their oral health is not affecting their well-being. If you would like to schedule an appointment to have your dog’s teeth checked, do not hesitate to contact our team at Animal Dental Clinic.