Feline Dental Model
This is a model of a normal adult cat dentition. Cats have six upper and six lower incisors, two upper and two lower canine teeth, six upper and four lower premolars and two upper and two lower molar, for a total of 30 adult teeth.
The incisor teeth are the tiny front teeth. The canine teeth are the “fang” teeth. Incisors and canine teeth only have one root each. The premolars are the large teeth located behind the canines, but in front of the molars. Most of the premolars have two roots, with the exception of the carnassial teeth (upper fourth premolar) which has three. The molars are generally smaller and flatter than the premolars, have anywhere from one to three small roots, and are located at the very back of the mouth.
Canine Dental Model
This is a model of the normal adult canine dentition. A “normal” dog has six upper and six lower incisors, two upper and two lower canines, eight upper and eight lower premolars, and four upper and six lower molars, for a total of 42 adult teeth. Note that the upper incisors (the little front teeth) lie slightly in front of the lower incisors, preventing them from digging into the gum tissue. Because of the variation in the size and shape of the jaw in dogs of different breeds, there are many dogs with abnormal dentitions. “Extra” teeth are called “supernummary” teeth”, but we more commonly see missing teeth that do not erupt because of a lack of space. “Malocclusion” which means misalignment of the teeth because of misalignment of the jaws, is a very common problem in dogs
This is a schematic diagram showing the general anatomy of a tooth. The visible part of the tooth is called the “crown”, which is covered in “enamel”, and the invisible part of the tooth is called the “root”, which is covered in “cementum” and is hidden in the “socket” below the gum line. The socket is surrounded by the bone of the jaw. Inside the tooth is a ” pulp chamber” lined with cells that produce “dentin”, which is the material that makes up most of the body of the crown and root. This is the living part of the tooth. Disease of the pulp cavity is called “endodontal” disease, whereas disease of the socket and tissue that surrounds the tooth is called “periodontal” disease.
This is a sampling of pet teeth that have been removed at this clinic over the years. You can clearly see that the roots are as large as the crowns. The root anchors the tooth into the jaw which prevents the tooth from being easily dislodged, and very hard for the veterinarian to remove. Even diseased teeth are very difficult to remove. Care must be taken to minimize trauma to the surrounding tissue. In most cases we have to split the crown and roots into sections for easier removal, but if the gums are very badly diseased, the entire tooth comes out in one piece.
Retained Deciduous Teeth
This anesthetized six-month-old puppy has a very common problem we see in small breed dogs. He has retained deciduous (baby) upper and lower canine teeth. This can happen in any of the teeth, but we see it affecting the canine teeth most commonly. Normally the tooth bud of the adult tooth is forming at the tip of the root of the decidous (baby) tooth, and as it erupts, it pushes the baby tooth out of it’s path. Unfortunately the baby tooth will not budge in many small breed dogs, so the adult tooth is forced to come out around the baby tooth. This has a number of undesirable consequences. First of all, the adult tooth is forced into the wrong position, which can affect the alignment of the jaw and even cause damage to adjascent teeth and gums. If you look at the lower jaw in this puppy, the adult canine teeth are sitting too far “lingually” (toward the tongue) than they should be. A possible consequence is that the tips of the crowns can lacerate the palate when the dog tries to close it’s mouth. Secondly, the adult and baby tooth are both occupying the same socket. The problem with this is that the gums cannot form a perfect seal around the neck of the tooth, and plaque and bacteria will quickly invade the socket and periodontal disease will occur if the baby tooth is not removed within a few weeks. As soon as this is detected on physical examination, the pup should be anesthetized and the retained baby teeth removed. Any delay compromises the future viability of the adult tooth.
This small dog has advanced periodontal disease affecting the third upper premolar tooth. There is so much chronic plaque and tartar accumulation under the gumline that the gums and bone have literally disintegrated away from around socket that supports the tooth. The best way to prevent this from happening to your pet is daily tooth brushing, and following your veterinarians recommendations for professional tooth cleaning. In order to properly clean under the gum line, where the plaque is doing most of the damage, we must fully anesthetize pets to do the job properly. In this case, the tooth has to be removed because there’s no longer enough bone left to hold the tooth in place.
This picture shows a number of problems we see frequently in small animal practice. The first and fourth premolars are oriented at an angle to the long axis of the jaw (ie., they are in sideways). This has occurred because of tooth overcrowding. The jaw simply isn’t long enough to fit in all the teeth end to end. There is advanced periodontal disease affecting the first and second premolars, just as in the picture above. This dog also has “gingival hyperplasia” a benign enlargements of the gum tissue that can trap plaque and food material under the gum line and accelerate the onset of periodontal disease. The lumps you see are “epuli” which are benign growths that can displace or engulf teeth as they grow. Surgically removing epuli and hyperplastic gingiva is usually curative, but sometimes the affected teeth cannot be saved.
This digital photograph shows a fractured carnassial tooth crown in a dog, a common problem. The pink spots are exposed “pulp chamber”, which is the central chamber inside each tooth. This is the living part of the tooth, a cavity lined with cells that produce the dentin, the white substance that forms the bulk of the tooth. We know this fracture occurred recently because the spots are still pink. In most cases veterinarians see crown fractures weeks or even months after the fracture occurred, at which point the spots have turned black. The veterinarian can differentiate black spots caused by “pulp exposure” from black spots caused by “tertiary dentin” (blackening due to damage to the dentin) by examination with a dental probe, and dental x-ray. Tertiary dentin is hard and smooth, whereas exposed pulp is kind of soft and gummy. A dental probe will slide right over tertiary dentin, but the tip will stick in exposed pulp, and sometimes bleeds when one removes the probe. Dental x-ray is a more reliable diagnostic tool as it can also detect tooth root abscess and bone loss, which helps determine whether the fractured tooth can be saved or not.
Tooth fractures are immediately painful. Ask anyone who’s fractured a tooth or had a tooth root abscess. The pain becomes progressively worse within hours as bacteria invade the chamber causing an infection along the entire length of the pulp chamber, right to the tip of the root. Antibiotics will temporarily control the infection and reduce the pain, but something needs to be done to permanently solve the problem. If the dental x-ray shows no abscess or bone loss, a root canal can be performed to save the tooth. Fractured teeth are more commonly extracted because the cost of root canal is prohibitive for many pet owners, and some dogs will fracture the tooth again after root canal and placement of an artificial crown. But the most common reason that fractured teeth are extracted is because the problem is presented for treatment after the tooth is too diseased to save.
Fractured teeth are very painful, but pets can’t tell you about it, so they just have to put up with the discomfort until somebody detects the problem. Have your pets teeth checked by the veterinarian regularly, or anytime you notice something isn’t quite right. If a fractured tooth is detected, the pet should start taking antibiotics immediately, followed by a root canal or extraction of the tooth within a week or so.
This digital photo shows another very common problem: advanced periodontal disease. Have a look at the probe lying against the teeth. The tip is situated at the “neck” of the tooth, which is where the crown ends and the root begins. In this case, there’s about 5 mm of exposed root, because of the bone that originally surrounded the root has simply disappeared. That means the tooth has lost about 25% of the bone that holds the tooth in place. This damage is irreversible. There’s nothing we can do to get the bone to grow back. In this case, as is often the case, two teeth are affected, the carnassial and the adjascent maxillary molar tooth. If the teeth are already loose, or the x-ray shows more extensive damage, the teeth should be removed.
Tooth Root Abscess
The arrows on this x-ray point to a tooth root abscess of the mesial root of the carnassial tooth of a dog. The area around the tooth root is black because the bone around the root is gone. This tooth needs to be extracted because the bone loss is extensive and permanent. No amount of antibiotics will solve this problem.
This photograph shows a carnassial tooth that is fractured in two places. The probe is holding up a fragment of crown separated from the rest of the crown due to a “slab fracture”, which is something we see frequently in dogs. Note that the gum is still clinging to the fragment, because this tooth was perfectly healthy before the fracture occurred. Note also that there is a pink spot at the tip of the crown, which is pulp exposure due to a second fracture.
This x-ray of the mandible of a cat shows another all too common problem. On the x-ray you can see, from left to right, the roots and crowns of the second and third mandibular premolars and the first mandibular molar tooth. Have a look at the second premolar, the first tooth on the left. Can you see the great big hole in the crown? That’s a stage 5 “feline ondontoclastic resorptive lesion”, or FORL for short. Notice that the root is already becoming “‘resorbed” ie, it’s disappearing. Extraction of this tooth will relieve this cat of a great deal of pain and suffering. You may also have noticed the bone recession that is occurring on the other two teeth due to periodontal disease. The bone does not extend all the way to the neck of each tooth, as it should.