Tooth Root Abscesses in Cats

Introduction

Also called an apical abscess, a tooth root abscess is a fairly common occurrence in the teeth of cats. It is a painful condition where infection, introduced into the pulp canal of the tooth, travels along it, and forms an abscess at the apex, or tip, of the tooth root. Based on what we know from abscesses in humans, pain caused by pressure within the tooth can range from low throbbing to intense, continuous pain.

An abscess is a collection of pus that spreads along the path of least resistance from the apex of the tooth to various locations. It can move through the apex of the tooth and the facial bones, and create cellulitis leading to a draining tract through the skin of the face.

Alternatively, it can move through the bone around the tooth, and to drain through the alveolar mucosa above the mucogingival line (parulis) inside the mouth. The former is not very common in cats, and the latter is more likely to be found by your veterinarian during an oral examination.

In the vast majority of cases (90%), a broken tooth is the cause of the abscess. Usually a fracture with an open pulp canal is the culprit. Sometimes a tooth with a pulp canal that is barely sealed can be abscessed.

Although the exact cause of the abscess may not be known, the treatment remains the same—drainage of the abscessed site. Unfortunately, drainage of the site of an abscessed tooth almost always means extraction of the tooth.

Apical abscesses can involve any teeth, although the majority involve the maxillary fourth premolars. These are important teeth in the upper jaws that are used for powerful functions such as tearing, crushing, and chewing food and bones.

For this reason they take the brunt of wear and tear, and unfortunately are prone to injury, particularly slab fractures which can allow bacteria to enter the pulp canal, inviting an abscess to form.

Preoperative antibiotics are recommended in the case of abscessed teeth to help prevent the spread of infection, to help treat the abscess, and treat periodontal disease if present. Antibiotics usually are continued through the recovery phase of the extraction to minimize the potential for bacterial spread to other organs and cause systemic illness. For these reasons, it is important to take tooth abscesses seriously and to administer medication as directed by your veterinarian.

Occasionally, Phoenix abscesses can develop. Phoenix abscesses are chronic and non-active but can become exacerbated and painful. Alternatively, a pet may have a sterile abscess (without bacteria). Both of these abscesses require drainage and treatment. 

Risk factors for tooth abscesses include:

• Trauma to the tooth which in turn traumatizes the pulp canal. Such trauma can include a direct blow with subsequent crown fracture.
• Chewing on hard objects. This activity commonly causes fourth premolar fractures.
• Fighting with other cats.
• Pulling on the teeth in vigorous play.
• Bone plating or other dental work that damages the roots.
• Severe periodontal disease causing deep gingival pockets.
• Bacteria from dental caries (cavities), exposed dental tubules, or extension into the endodontic system.
• Heat causing pulp injury— via electric cord burns, electrocautery, over-polishing, or drilling.

Clinical Signs of Tooth Root Abscesses

• The tooth is broken (90% of the time), or the tooth is barely sealed over from the exposed pulp canal. The doctor can almost always insert the end of the dental probe into the pulp canal.
• Discoloration of the tooth. 
• Tooth is no longer sensitive. However, if a tooth was recently fractured it may still be sensitive. 
• Swelling of the face—usually swelling is localized to one area of the face but may be diffuse. Most often facial swelling presents as a large swelling under the eye on the same side as the affected tooth, since the fourth maxillary (upper) premolar is commonly fractured and abscessed.
• Draining tract on face, commonly seen under one eye, may be due to maxillary fourth premolar abscess.
• There may be a parulis (red, raised lesion seen at the mucogingival line or above) noted on oral examination. 
• The face might be tender, or very painful if there is an abscess that is not yet draining.
• The tooth may be asymptomatic for years despite the presence of inflammation and bacteremia. Eventually these signs will be seen. 
• A deep periodontal pocket may be present if no fracture is present.
• Mandibular fracture can cause abscesses, especially of the lower canines or first molars. These fractures are often seen in cats after being hit by a car.
• Loose, painful teeth.
• Facial lymphadenitis.
• Reluctance to chew, and may see accumulation of plaque and tartar.
• Some pets are reluctant to eat or stop eating, but most eat well.
• Sinusitis—the maxillary sinus is most often affected.
• Sense of smell may be affected. This may lead to decreased appetite in cats.

Diagnosis

The diagnosis for an apical root abscess is done by oral radiography (X-rays) using an expensive X-ray probe exquisitely positioned within the mouth. This procedure must be performed under general anesthesia because although most pets are gentle and well-behaved, they cannot help but bite on the X-ray probe (think about how you must gently bite on the X-ray films during your dental X-rays and how uncomfortable it is holding still for that short amount of time!).

Diagnostic procedures may include:

• Insertion of gutta percha into the sinus tract. To help determine which tooth is affected or if a fistula has developed, gutta percha can be inserted into the sinus tract and a radiograph then taken.
• Transillumination. Transillumination with a strong fiber-optic light can be used to help distinguish healthy from necrotic pulp, and to compare the same tooth on both sides of the mouth.

When a tooth root is abscessed, pus and inflammation are evident in the apical area. If the tooth root abscess is chronic, a fibrous capsule and draining tract may surround the apical area.

Differential diagnoses

The differential diagnoses for abscessed teeth include:

• Normal anatomy on x-rays including the mental foramen, especially the middle mental foramen just apical to the second mandibular premolar.
• Tooth resorption without apical lucency.
• Tumor including squamous cell carcinoma and fibrosarcoma which can displace teeth.
• Cementomas—enlarged apical roots with a thin radiolucent zone continuous with the periodontal ligament.
• Cysts—large lytic area involving any part of the unerupted crown and or the root.
• Apical periodontal granulomas, radicular cysts.
• Dentigerous cyst—radiograph shows a tooth within the cyst–the follicular cyst of an impacted or embedded tooth.
• Periapical scar—in an endodontically treated tooth when there is no increase in lucency in the apex more than 6 months after treatment.
• Must be differentiated from the chevron effect–this can be seen radiographically in the small teeth that sometimes abscess.

Treatment

Treatment of an apical tooth abscess involves the following:

• Extraction of the tooth, to provide surgical drainage and remove the focus of the infection.
• Curettage of the apical infected area.
• Chronic abscesses may require surgical removal of granulation and curettage of any draining tract.
• Endodontic root canal or surgical root canal if the apical lesion is large, specialty dental care is available and can be afforded.
• Cold packs on the treated area before and immediately after surgery can help reduce inflammation, if the pet will allow it.
• Appropriate pain control before, during, and after extraction for at least several days.
• Provide oral rest while healing: soft food only.
• Broad spectrum antibiotics preoperatively to prevent systemic spread of infection and improve tissue quality for best surgical outcome.
  • Clindamycin is recommended due to its excellent bone penetration.
  • Amoxicillin/clavulanic acid is a good second choice.

Potential Outcomes

With proper drainage and treatment, the prognosis for an apical root abscess is excellent. Follow your veterinarian’s orders for post-surgical care. Keep in mind that tooth root abscesses are deep in the tooth, tissue, and bone, and can take an extended period to resolve.

Therefore, always use antibiotics as prescribed and use them until they are finished. This helps make sure infections are cured, don’t recur, and helps prevent drug resistance from developing. Also be sure to take your pet to any recommended recheck veterinary visits. Veterinarians often want to evaluate the post-extractions sites of abscesses to be sure the tissues are healing appropriately.

Maintaining good oral health and preventing injury to your pet’s teeth are the best ways to prevent tooth abscesses. Taking care of apical abscesses as soon as they are diagnosed helps prevent further pain, and/or damage to your pet’s teeth and oral cavity. Allowing abscesses to go untreated increases the chances of damage to their facial bones, adjacent teeth, and possibly even their eye on the side of the abscess.

Watch for the upcoming article “How to Brush Your Cat’s Teeth” at PetHealthHarbour.com for more information and some great tips on how to get started with an excellent home care program. You can help your pet have healthier teeth and gums and hopefully help prevent dental problems in the future.

You can’t always prevent tooth fractures but your increased awareness helps you be a better pet owner. Every step you take to improve your pet’s dental health will improve their overall health too. Keep up the good work!

This enzymatic toothpaste helps to clean your pet’s teeth as you apply it by wiping, rubbing, or scrubbing with gauze, finger wipes, or a brush. Just do the best you can as often as you can.

Use whichever end of this double sided brush fits your pet’s mouth and teeth the best, to gently touch, then rub, then scrub, then eventually brush their teeth the best you can, as often as you can. Just do your best!

These little finger wipes are great for reaching along inside the lips of your pet to get to the back teeth. Hold their mouth gently closed, and just rub a little as you get them used to the feeling. Do the best you can to gently rub and scrub those teeth a little more day by day. Even if you never graduate to a toothbrush, you’ll help a lot to keep your pet’s mouth healthy by scrubbing with finger wipes!

This antibacterial chlorhexidine rinse is especially helpful after extractions or dental work. It can be used to flush the extraction sites or the whole mouth, and to prevent and treat periodontal disease.