25 Rubber toy technique and alveoloplasty
The owner is active in the show ring and thus concerned about the malocclusion. In fact, the owner is more worried about the aesthetics than the developing pathology (palatal trauma). The dog is showing no obvious signs of discomfort. He is very active and enjoys playing with toys. The case was referred to us for evaluation and treatment.
Figure 25.1 Lateral photograph (a) and occlusal photograph (b) of the malocclusion. The right lower canine is occluding with the gingival mucosa of the diastema. The malocclusion is the same on the left side.
In some animals, the mandible is too narrow with respect to the upper jaw. The result is that the lower canines impinge on the maxillary gingivae or the hard palate instead of fitting into the diastema between the upper third incisor and upper canine on either side. The animal may not be able to close its mouth and injury to the gingivae or palatal mucosa commonly occurs. In untreated severe cases (i.e. where the lower canines are upright and occluding with the palatal mucosa rather than the gingivae of the diastema), an oronasal communication may develop over time.
This malocclusion is seen in both the primary (deciduous) and permanent dentition. Persistent primary canines will further exacerbate the condition as the permanent canines erupt medially to their primary counterparts in the mandible. The incorrect dental interlock will interfere with the normal growth in width and length of the developing mandible. The condition can also be caused by persistent primary mandibular canines in a mandible of normal width.
In this case, the upper and lower jaw were of normal length; the mandible was narrow with respect to the upper jaw, but there was sufficient diastema for the lower canines to form a correct interlock if they were moved just slightly laterally.