Question: A local dentist, trained in the U.S., choose to file the wolf teeth down to just below gum-level in preference to the standard extraction procedure. What are the chances of infection due to exposed pulp? Wolf teeth (in my short experience) does not seem to behave in as predictable a manner as the rest of the dental family!
Answer: From the front to the back of the mouth are the incisors, canine teeth (if present), wolf teeth and a set of 3 deciduous premolars (first 3 cheek teeth), which are replaced by a set of 3 permanent premolars. Located in the deepest of the back of the mouth are the permanent molars (second three cheek teeth). All have some structural differences from each other but have basically the same functional makeup of types of cells. The clinical crown is the part of the tooth erupted from the gum and visible, the outer shell is a layer of cement, a layer of enamel (may be in exaggerated folds) and then internal cement. Within or central to the internal cement there are one or more additional rings of enamel and types of cement. And in the “middle” of the tooth there is dentin. The dentin, most central in the tooth, is formed by cells lining the blood pulp cavity. Those cells fill the cavity from the occlusal (chewing) surface towards the root of the tooth as the tooth wears, preventing pulp exposure and subsequent death of the cells located in and lining the pulp cavity. If the interior pulp cells of the tooth become infected, it is a pulp infection. If it travels up to the root, it becomes an apical root infection. There are various reactions that occur to limit infections and pulp stones and bone sclerosis are a couple that are common in horses with pulp exposure and root infections. Sometimes if the insult is relatively small, these stop the invasion of bacteria and cell death and goes no further, or the infection may spread into apical root infections and bone infections. In bone, an abcess forms (to wall off the “enemy” from the rest of the body) and may cause swelling and visible drainage of pus if there is an outlet such as into the sinus cavity, or an easy route to the outside of the body.
The healthy equine tooth is also attached to the bone socket (alveolar bone) by living ligament cells that adhere to the cement layer of the tooth and to layer of cells on the bone surface in the socket. These cells (forming Sharpey’s fibers) have a special role in herbivores that continue erupting teeth, because they are the cells that act to “crawl” the fully formed tooth out of the bone as it wears, and provide a continuous grinding surface for macerating fibrous foods. So the second place that a “tooth” infection can occur is around the inside of the socket, if the ligament holding the tooth becomes open to bacteria (such as occurs with geriatric horses when the tooth becomes short and is mechanically “wiggled”) or if a disease (such as pressure necrosis) causes the death of the ligament cells. Either way, the tooth loosens in the bone. Sometimes this is followed by the bone cortex (surface) inside the alveolar socket reacting to bacteria to form a cement-like attachment across the dead ligament to the tooth root.
The “wolf” tooth is morphologically a usually very small, vestigial (genetically disappearing) premolar tooth. Some wolf teeth are tiny and others may be large and long (2+ cm) and even have a molar like shape and may have a small blood pulp within. Some horses have one or no wolf teeth and a few have lower wolf teeth or displaced blind wolf teeth that do not erupt through the gum or sit in unexpected places like along the interdental space (bars) of the mouth. In horses older than 2 ½ years that have normally located wolf teeth (i.e. right near the second deciduous premolar tooth) the wolf tooth roots may already have been damaged by the acid bursa of the newly forming and perhaps already erupted permanent second pre-molar tooth. These may remain loose or may have sclerosis later and attach to the bone. I tend to be very cognizant of the location of the new nearby permanent tooth when removing wolf teeth that are near newly erupting, but not yet visible, permanent teeth. My goal then is to remove all the fragments of any size. If there was a question between leaving a fragment or protecting the new tooth. I opt to protect the tooth with certainty and make a note on the patient record to examine the area in a few months or next visit, removing any fragments remaining.
To finally answer the question in context, I believe the chance of an infection would depend on the size of the tooth, the age of the horse and whether a pulp is present in the tooth. I would guess that a chance of an infection of any significance would be very small.
My other thought to leave you with concerns the ligament condition over time. If the ligament allows the tooth fragment to migrate out, it may come in contact with soft tissue during riding much as the original spicule, or loosen and actually wiggle around in the gum against the bit. Since the whole reason to address wolf teeth at all is to insure a comfortable and safe bit experience for the horse and rider, purposefully leaving a fragment seems counter-intuitive to me. A small surgical procedure with an anesthetic block and the appropriate elevators and forceps is reliably very quick and simple, and without the root fragment present, the bone and gum heal amazingly fast; so… why not just remove it all? Cindy Allen, DVM, Bit O’ Magic Equine, Aluchua, Fla.