Your Pet’s Tooth Is Fractured What You Need to Know
by John Maniatty, VMDKnowing the basic anatomy is essential for you to relay to your vet what you see when it happens and for them to explain the plan to you. The tooth is broken into three sections: crown, neck, and root(s). The crown is the tooth above the gum line, also called gingiva. The neck is at the gum line and connects the crown to the root(s). The root is just below the neck, anchors the tooth in the bone, and has an opening at the deepest portion of the bone, allowing blood vessels and nerves to enter the tooth’s center, called the pulp canal.
The crown is encased in enamel. The neck and root are encased with cementum. The cementum is attached to the bone (alveolar bone) by periodontal ligaments. Below the enamel and cementum is the dentin. Dentin is mineralized tissue with tubules running through it to allow mineral and organic material to travel and replenish dentin as it is worn. The tubules allow sensations to be felt by the dentin-producing cells in the outer layer of the pulp cavity called odontoblasts. So, when the outer enamel is damaged and dentin is exposed, the tooth has a greater sensitivity to heat, cold, and pressure. There are
three types of dentin. The Primary is the dentin below the enamel. Secondary is dentin underneath the cementum. Finally, tertiary dentin is the dentin that replaces damaged dentin when the enamel or cementum has been removed. Tertiary dentin is darker yellow or brown, while primary or secondary dentin is white/yellow. The pulp tissue in the tooth’s center has the blood vessels, nerves, and odontoblasts.
Teeth can fracture for a few reasons ranging from blunt trauma to chronic trauma to a resorptive lesion that will lead an eroding tooth to break. Once a tooth has fractured, we need to determine what type of fracture it is, complicated versus uncomplicated.
A complicated fracture is when the tooth crown has fractured, and the pulp cavity is exposed. Exposure of the pulp cavity gives bacteria direct access to the blood vessels and nerves. With this type of fracture, the tooth will need vital pulp therapy, a root canal, or be extracted. Vital pulp therapy is usually done in a young dog
or cat and has a high success rate if completed within 48 hours of the fracture. However, after one week, the success rate drops to less than 50% and less than 25% after two weeks. A vital pulp therapy entails smoothing the tooth, then removing the infected pulp tissue and placing an alkaline material to seal it. Follow up-to assess the procedure’s success involves radiographs every six months for two years, then yearly. Continued breakdown or widening of the pulp cavity will indicate the tooth is dying, and root canal versus removal is suggested.
A root canal involves: Smoothing the fracture site. Removing all the pulp material. Placing an inert material in the pulp chamber.
The area is then sealed. Root canals have a 94% success rate, but if the inflammation of the tissue at the root tip occurs, the success rate drops to about 10%.
A fracture that does not include the pulp cavity is considered uncomplicated. Even though there is no pulp cavity exposure, pulpitis can occur due to dentin tubules allowing bacteria to pass through and access the pulp cavity that way. One study showed 24.3% of maxillary 4th premolars had endodontic lesions with this type of fracture. (1) Therefore, these need to be evaluated and treated.
Evaluating requires determining how long the fractures have been present, dental radiographs to see
if the widening of the pulp cavity has occurred, and does the fracture go below the gum line. Determining the length of time helps decide what type of treatment is an option. Fresh fractures tend to have sharp edges, and the tooth is still white.
Radiographs will allow us to tell if root or pulp cavity involvement. If the root is damaged by fracture or resorptive lesions, extraction may need to be performed. A fracture deeper than the normal gingival pocket will require regular cleaning every 6 -12months and at home brushing regularly. It would be best if you were committed to follow-up treatment for this to be possibly successful. If the pulp cavity is widening, a root canal or surgical removal will be needed. If the fracture site has a brown stain, tertiary dentin has been laid down, and the body has attempted to protect the tooth itself. Radiographs are still warranted to assess the pulp cavity and see if any infection is present.
Fresh fractures, <8weeks, that do not go below the gum line are good candidates for Bonded sealant therapy. Bonded sealant requires smoothing the tooth, acid etching, resin application, and light-curing. This seals the dentin and protects against infection. If the fracture is > 8weeks, most likely tertiary dentin has sealed the tubules, and bonding may be of minimal if any benefit. Follow up in 6 months with radiographs to see if the tooth is still healthy and recheck at the time of every dental; we like to refer to them as
complete oral health assessment and treatment (COHAT). Precious Paws Animal hospital now offers bonded sealant treatment.
1) Goodman AE; Niemiec BA; Carmichael DT; Thilenius S; Lamb KE; Tozer E; AE, Brooke. “The Incidence of Radiographic Lesions of Endodontic Origin Associated with Uncomplicated Crown Fractures of the Maxillary Fourth Premolar in Canine Patients.” Journal of Veterinary Dentistry, U.S. National Library of Medicine, June 2020, https://pubmed.ncbi.nlm.nih. gov/33063625/.