Inclined planes
Figure 4A-4D. Normal occlusion on the right side (4A) and malocclusion on the left side (4B) in a young standard poodle. In
4C, the linguoversion of the left mandibular canine tooth is causing trauma to the hard palate (arrow). An inclined plane
appliance was directly fabricated (4D) to correct this problem. This dog had a normal and healthy occlusion in just two weeks.
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Inclined planes are fixed acrylic or metal orthodontic devices that act as a ramp to direct teeth into a healthier position
(Figures 4A-4D). Inclined planes can be fabricated and installed directly while the patient is anesthetized, or they can be fabricated in
a dental laboratory from a laboratory stone model created from impressions of the dog's occlusion and cemented into place
at a subsequent appointment. Once installed, the inclined plane places tipping forces on the displaced tooth in a direction
determined by the slope and direction of the fabricated appliance. The correction usually occurs within two to four weeks,
at which time the appliance can be removed.
Camouflage orthodontics
Figure 5. Treating an anterior crossbite in a Scottish terrier by using an upper expansion device and an elastic power chain
on the mandibular incisor teeth. The upper expansion device is anchored to the maxillary canine teeth, and the owners are
instructed to use a key to crank the expansion screw at a predetermined interval (once a day to once every four days). The
mandibular incisors shown in this photograph have already been tipped caudally by the elastic power chain, which is anchored
to buttons cemented on the mandibular canines and fixed to the incisors by orthodontic buttons. The elastic chain also functions
as a retainer to prevent inadvertent rostral tipping of the incisor teeth.
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Another method used to treat linguoversion of the mandibular canines is so-called camouflage orthodontics, also called tooth extensions. Camouflage orthodontics involves building up the height and changing the shape of a tooth with dental plastics, so the newly
created crown tip occludes normally. In the case of linguoversion of the mandibular canine teeth, if the crown tip is diverted
buccally into a normal position, the forces acting on the tooth when the dog closes its mouth will tip it into a more proper
occlusion. When the natural tooth is in proper position, the plastic built-up crown tip can be removed.
Anterior crossbite
An anterior crossbite is a malocclusion of incisor teeth in which one or more of these teeth are not aligned in the healthy
scissor orientation. The incisor teeth may be evenly aligned, where they impact each other's incisal edge, or the mandibular
incisors may be rostral to the maxillary incisors in a reverse scissor orientation. An anterior crossbite can result in abnormal
tooth-on-tooth contact or, possibly, in abnormal soft tissue contact. In these cases, treatment is warranted to prevent periodontal
or endodontic problems.
The basic tenets of therapy are to move the maxillary incisors rostrally and to move the mandibular incisors caudally. Camouflage
orthodontics works well in mild cases; more severe cases will require the use of more sophisticated orthodontic appliances,
such as an upper expansion device combined with lower orthodontic buttons and elastic (Figure 5).
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