Managing permanent dentition malocclusions
If a problem does not self-correct, several options for therapy are available, depending on the presentation. Almost any orthodontic
problem can be camouflaged with an orthodontic appliance. However, there are important ethical concerns about orthodontic
therapy in animals.2,7 First, you must inform the client that most orthodontic problems are genetic in origin and that correcting the bite will
not correct the genes. In addition, most orthodontic cases are cosmetic only, and subjecting a patient to the discomfort of
an orthodontic appliance for the client's vanity may not be ideal. Finally, when the malocclusion is causing trauma, orthodontic
therapy requires numerous anesthetic episodes, and other options may require only one procedure.
Class I malocclusions. Base narrow occurs when the mandibular cuspids exhibit linguoversion and cause palatine or gingival trauma (Figure 13). Intervention is critical in these cases. Options for therapy include moving the tooth orthodontically by removing a wedge
of gingival tissue, placing composite crown extensions on the mandibular cuspids, or applying an incline plane (Figure 14). In addition, some dentists use ball therapy, which is inexpensive and noninvasive.9
If the owner wants one-step therapy, the offending area of the tooth can be removed. This is best achieved by coronal amputation
and vital pulp therapy (Figure 15). When performed skillfully, this procedure enjoys an excellent success rate.10 However, the client must be cognizant of the need for follow-up radiographs. Also, some success has been seen with surgical
movement of the tooth.11
Finally, the tooth may be extracted. Because of the size of the tooth and the importance of the mandibular cuspids in tongue
retention and aesthetics, this is generally not the treatment of choice.2
Class II malocclusions. These malocclusions cause marked pain and inflammation that result secondary to the palatine trauma. Treatment of this condition
is best achieved with coronal amputation and vital pulp therapy.
Mild cases can be treated orthodontically with a variant of an incline plane, but it is much more difficult to apply this
in patients with class II malocclusions than in patients with base narrow malocclusions because of the trapping of the mandibular
cuspids palatal to the maxillary cuspids. Severe cases can also be treated orthodontically by moving the mandibular cuspids
into position distal to the maxillary cuspids. Finally, the tooth may be extracted.
Class III malocclusions. These malocclusions are generally only cosmetic and require no therapy. Orthodontic correction can be performed, but it is
not recommended. In addition, it should be done only after strict genetic counseling. In rare cases, there may be maxillary
lip trauma from the mandibular cuspids (especially in cats). In these cases, coronal amputation and vital pulp therapy or
extraction can be performed.
The eruption of the permanent dentition occurs within a fairly short time. Most breeds follow standard eruption times (Table 1), but some breeds have normally delayed eruptions. Teeth that have not erupted by the normal time (as defined by texts or
by context of the eruption of the surrounding or contralateral teeth) should be considered pathologic. Patients most commonly
have an abnormal space in the normal arcade (Figure 16A). Occasionally, however, a deciduous tooth will be intermixed in the permanent dentition (Figure 16B).
Table 1. Eruption Times for Teeth in Domestic Dogs and Cats*