• (For more information or questions, contact Dr. Hewitt at 702.395.1800, or by e-mail at: dr.hewitt@cheyennewest.com)

    PUPPY:
    When a pet is born, it has no visible teeth. Within a few weeks, the baby (deciduous) teeth erupt. During this time, the adult teeth are starting to develop in the bones of the upper and lower jaws. As these teeth develop, they start to erupt. As the adult teeth erupt, the roots of the baby teeth deteriorate in the path of the adult teeth. When the adult teeth reach the surface of the gums, the baby teeth fall out, and the adult teeth erupt to replace them. The normal time frame for the adult teeth to erupt is between 4 and 7 months of age. In some smaller breeds, this eruption can be delayed, however.

    In some cases, the baby teeth erupt and are pointed in an abnormal direction. There is a specific abnormality called base-narrow mandibular canines. In this abnormality, the lower (mandibular) canine teeth (fangs) are positioned in such a way that causes them to impact upon the soft tissues of the palate, rather than lying between the upper canines and incisor teeth (which is their normal position). This causes pain, which may be seen as difficulty or hesitation when chewing. However, many pets with this condition show no outward signs of mouth pain, and owners are not aware that this problem exists until it is found by their veterinarian.

    This condition often occurs concurrently with another type of malformation called brachygnathism, which is when the lower jaw is shorter than normal. Brachygnathism is a birth defect that is often hereditary. However, the argument has been made that when the baby teeth become “stuck” in the tissues of the palate, that this can make brachygnathism worse than it would have otherwise been. Some even argue that base-narrow baby teeth can even cause brachygnathism by preventing the lower jaw (mandible) from growing out to its full potential. Brachygnathism will often result in abnormal position of the adult teeth, after the baby teeth are lost.

    Be aware that the baby teeth that the puppy has will be lost, usually around 6 months of age. However, the teeth that are in this abnormal position cause pain by striking against the soft tissues of the roof of the mouth. In addition, as noted above, they can potentially cause or enhance additional abnormalities (brachygnathism), if they are left in place.

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    Normal position of the adult canine teeth

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    Base-narrow deciduous canine tooth

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    Palatal trauma caused by teeth at left

    The best treatment at this point is to extract the affected deciduous mandibular canine teeth. This will both eliminate the pain caused by the malocclusion and allow the mandible to grow out to its full potential. However, be aware that many (if not most) of these puppies have brachygnathism as a genetic disorder. The genetically affected puppies will ultimately have brachygnathism regardless of treatment at this age. Extraction of the deciduous teeth will eliminate the pain and soft tissue damage to the palate, which is the main goal of addressing this problem early. If the mandible is genetically predetermined to be shortened in these animals, we will still need to perform some type of treatment on the adult mandibular canines when they erupt, but the pet will be free of the significant pain caused by this disorder until that time.

    ADULT:
    If the adult teeth erupt in such a way that they are in the abnormal position of impacting the soft tissues of the roof of the mouth, and they are left in place, they will cause pain, difficulty chewing, and damage to the palate. Ultimately, this can result in progressive soft tissue damage which often damages the upper canine teeth. This usually results in an opening developing between the mouth and the nasal cavity, called an oronasal fistula (ONF). When ONF develops associated with the upper canine teeth, the only practical option for treatment is to extract the upper canines, surgically repair the defect, and treat the lower canines (see below) in order to stop further damage and pain.

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    Base-narrow adult canine teeth

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    Base-narrow adult canine teeth

    There are several different treatment options for base-narrow canines in the adult pet, based on the severity of the problem. Some of the more commonly used treatment options are:

    1) Gingivoplasty. If the mandibular canine teeth are mildly affected, we can often resolve the malocclusion by doing a relatively simple procedure called “gingivoplasty.” In this procedure, a small amount of gingival (gum) tissue is removed in order to create a natural ramp to guide the mandibular canine teeth into the proper position. This is a relatively inexpensive procedure, and is almost always accomplished in a single procedure, with minimal to no follow up treatment.

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    Before gingivoplasty

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    After gingivoplasty

    2) Gingivoplasty plus composite extensions. In this procedure, the gingivoplasty is enhanced by an additional step in which the length of the mandibular canine teeth is extended by placing a small amount of a composite filling material on the tips, in order to enhance their contact with the natural ramp that is created. This procedure is still relatively simple, but requires a follow-up anesthetic procedure at a later date, in order to remove the composite from the canine teeth after they have moved into the proper position.

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    Before treatment

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    Gingivoplasty with composite extension

    3) Orthodontic appliances. This is best performed when a pet is 10-12 months old, but can still be performed earlier or later, if necessary. There are different orthodontic appliances that can be used. The most common appliance used is called an incline plane. The other procedures that can be performed will not be discussed here. The placement of an incline plane is a process where we create an artificial appliance or ramp out of acrylic or metal that guides the mandibular canines into the proper position. It requires at least 2 anesthetic procedures (one to place the appliance, and one to remove it) for the acrylic plane, and 3 anesthetic procedures (one to get impressions for the manufacture of the appliance, one to place it, and one to remove it). The length of time the appliance is left in place is determined by several factors, but is usually 1-4 months. If the pet damages the appliance (more common with acrylic than metal appliances, usually due to inappropriate chewing behavior), then an additional anesthetic procedure will be required, at additional cost, to replace the appliance.

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    Acrylic plane

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    Acrylic plane

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    Metal incline plane

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    Metal plane, side view

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    Occlusion with metal plane

    4) Petalign system. In this procedure, the pet is anesthetized for impressions of the teeth, and the impressions are sent to a special laboratory where they prepare a full set of snap-in dental appliances. The dental appliances snap in place and do not require anesthesia to place or change. The appliances are changed according to the manufacturer’s schedule to move the lower teeth into place.

    The advantage of this procedure is that there is only one anesthetic procedure required to get the initial impressions. The remainder of the process does not require anesthesia. There are few disadvantages to this system, other than requiring you to change out the trays intermittently. This is a relatively new system to veterinary medicine, and so far has been tested and used successfully for this type of malocclusion. Specific cost estimate for the manufacture of the Petalign trays varies from pet to pet based on the required movement of the teeth and other factors. Photos of the teeth are forwarded to the company and they then provide us with a cost of the trays. The manufacturer guarantees that the system will work. The guarantee is that, if the desired result is not obtained, they will manufacture as many additional trays as they need to in order to accomplish the desired movement of the teeth at no additional charge.

    5) Crown reduction. In this procedure, the mandibular canine teeth are surgically cut off (crown reduction) at a level where they will not cause further damage to the soft tissue of the roof of the mouth or to other teeth. After the teeth are reduced in size, the pulp (living tissue inside the teeth) is exposed and a procedure called a vital pulpotomy is performed. In this procedure, we remove a small amount of pulp, place a pulp dressing to protect the living tissue within the tooth, and then place a composite restoration, or “filling” in the tooth. The advantages of this procedure are that the tooth is maintained as a living, functional tooth, and the damage and pain caused by the malocclusion is resolved. The disadvantage is that there is a small percentage of teeth undergoing this procedure that will develop inflammation of the pulp or bacterial invasion of the pulp, resulting in the death of the affected tooth. After a vital pulpotomy is performed, we will do follow-up anesthetized dental x-rays every 6 months for approximately 2 years, in order to assure that the procedure was successful. If the procedure fails and the tooth becomes non-vital, then we must either do root canal therapy on the tooth, or extract the tooth at that time. This is a very uncommon, but possible, complication.

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    Pre-operative

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    After crown reduction

    6) Extraction. The advantage of extraction of the mandibular canine teeth is that it will eliminate the problem in a single procedure, with minimal follow-up and rare serious complications. The disadvantage is that the dog will lose the function of the mandibular canine teeth. The mandibular canine teeth functions include gripping objects, holding the tongue in proper position inside the mouth, and making up a significant part of the structure of the lower jaw. Without these teeth, the tongue will hang to either side of the mouth, occasionally leading to minor trauma to the tongue from the other teeth. There will also be some weakening of the mandible (lower jaw). In some cases when we do extractions of mandibular canine teeth, we often place a bone graft material that helps to induce new bone formation and enhance the strength of the jaw.

    GENETIC IMPLICATIONS:
    The presence of base-narrow adult canine teeth is considered to be a hereditary defect, and dogs with this condition should not be bred.

    Additional information and handouts can be found online at the web sites of:
    The American Veterinary Dental Society – http://www.avds-online.org/resources.htm
    The American Veterinary Dental College – http://www.avdc.org/?q=node/2
    Veterinary Partner web site – http://www.veterinarypartner.com
    Veterinary Oral Health Council – http://www.vohc.org

    Updated June 2011

    CHEYENNE WEST ANIMAL HOSPITAL
    3650 N. Buffalo Dr.
    Las Vegas, NV 89129
    702-395-1800
    Brian Hewitt, DVM