Download Applied Dentistry for the Veterinary Technician

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Occlusion
 Orthodontics studies the way in which the teeth meet
each other (occlude).
 Occlusion is defined as the normal position of the teeth
when the jaws are closed.

In normal occlusion, teeth come together in a
__________________.
Scissor Bite Evaluation
 Scissors bite is evaluated in three locations:
1. The mandibular canine tooth resides in the interdental
space of the upper third incisor and the upper canine
tooth.
2. The upper fourth premolar is labial to the lower
first molar, which together, constitute the
___________ teeth.
3. Maxillary incisors are slightly rostral to the
mandibular incisors.
Normal Occlusion
Normal scissors occlusion in a dog:
Rostral view of incisors and canine teeth
Normal Scissors Occlusion:
When all three locations are normal- the premolars
interdigitate toward the opposing interdental space.
Review: Can You Name These Structures?
Malocclusion
 Malocclusion is an abnormality in the position of
the teeth.

It can occur in any of the three head shapes, but is more
common in brachycephalic breeds.
 There are four classes of malocclusions.
(Class I, II, III, and IV)


Class I- easily fixed with orthodontic correction OR not needed
Class II-IV are skeletal malocclusions due to differing jaw length
Class I: Rostral Cross-bite
 Maxillary incisors are ________ to the mandibular
incisors.
 Very common malocclusion in veterinary dentistry.
 Thought to occur secondary to retained deciduous
incisors.
 Treatment consists of orthodontic movement or
extraction of the abnormal teeth.

Treat vs. not treat?
Rostral Cross-bite
Class I: Caudal Cross-bite
 Maxillary premolars/molars are positioned lingual to
the mandibular opposing premolars/molars
 Occurs occasionally in dolichocephalic breeds.
 More frequent professional prophylaxis will be
needed for these pets.
Caudal Cross-bite
 The maxillary fourth
premolar is positioned
abnormally inside of the
lower first molar tooth.
 This condition did not
require treatment as the
pet had a comfortable and
functional
occlusion (bite).
Class II: Mandibular Distoclusion
 Mandibular brachygnathism:
abnormally short mandible, normal maxilla
 Referred to as “overshot”
 Lack of self-cleaning ability and can create painful
palate abrasions.
 Not an accepted standard in any breed.
Mandible is shorter than
the normal maxilla.
Class III: Mandibular Mesiocclussion
 Mandibular prognathism: abnormally long
mandible, normal length maxilla
 Referred to as “undershot”
 These dogs will lose some of their self-cleaning
ability and trap plaque and debris more easily.
 Maxillary incisors can traumatize the mandible.
 Accepted as normal in brachycephalic breeds
such as Bulldogs, Pekingese, Boston terriers, Pugs,
and Persian cats.
Mandibular Prognathism
Mandible is
longer than
the maxilla.
Mandibular Prognathism
Asymmetrical Malocclusion
 Each upper and lower right and left quadrant of the
mouth is independent of the other, resulting in
uneven growth which produces a wry occlusion
(wry bite).
 In its mildest form, a one-sided prognathic or
brachygnathic bite forms. In more severe cases, a
crooked head and bite develop.
 A triangular opening (open bite) will also appear in
the incisor area where the affected incisors are
displaced vertically and do not meet.

In severe cases, the tongue protrudes from the open bite.
Wry Mouth: One quadrant develops unevenly
from the other quadrants
Wry Occlusion
Persistent Deciduous Teeth
 Interfere with normal eruption pathway of permanent




teeth  ____________
Are a reservoir for debris  dental disease
Early detection is key!
Common in small breed dogs
Extraction is almost always necessary

Referred to as Interceptive Orthodontics
*Note: deciduous teeth are numbered differently in the
Triadan system (500, 600, 700, 800)
Persistent Deciduous Canine Teeth
Polydontia
 Supernumerary teeth should not be confused with
retained deciduous teeth.
 Unless extra tooth causes crowding, no treatment is
necessary.

Occasionally the extra teeth will erupt in an abnormal angle or
be impacted.
 If crowding: increased chance of periodontal disease.
(Extraction necessary)
Supernumerary Teeth
Deciduous or Permanent?
 Radiographs aid in
differentiation
Hypodontia
 One or more teeth (usually incisors or premolars) do
not form in the dental arcade.
 Un-errupted permanent tooth or hypodontia?

How do you confirm?
 If permanent tooth is absent, a baby tooth will often
remain in the arch for months to years.
 No treatment; usually does not cause any problems.