Download Dentistry- KJT- STUDENT part 2

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 scissors bite.

The skull shape of an animal can make them prone to
specific malocclusions.
Scissor Bite Evaluation
 Scissors bite is evaluated in three locations:
1. The mandibular canine tooth resides in the
________________ 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 ___________ to the
mandibular incisors.
Normal Scissors Occlusion:
When all three locations are normal the premolars
interdigitate toward the opposing interdental space.
Mesocephalic Breeds
Well proportioned skull width and maxillary length;
Ex. Dalmations, Labs, German shepherd dogs.
Dolichocephalic
Narrow skull and long maxilla;
Sight hounds, collies & Siamese cats.
Brachycephalic Breeds
Wide skull with a short maxilla;
Pugs, Bulldogs & Persian cats
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.

Could also occur due to trauma
 Treatment:
 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.
 Treatment:
 Extractions or more frequent professional prophylaxis will be
needed for these pets.
Caudal Cross-bite
 The maxillary fourth
premolar is positioned
abnormally inside of the
mandibular first molar.
 This condition did not
require treatment as the
pet had a comfortable and
functional occlusion.
Class II: Mandibular Distoclusion
 Appears as mandibular brachygnathism-
abnormally short mandible, normal maxilla
 Referred to as “overshot”
 Problems:
 Lack of self-cleaning ability
 Can create painful hard palate abrasions
 Never an accepted standard
Class III: Mandibular Mesiocclussion
 Appears as mandibular prognathism-
abnormally long mandible, normal length maxilla
 Referred to as “undershot”
 Problems:
 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
Persistent Deciduous Teeth
 A deciduous tooth that remains after the adult tooth
has already erupted
 Can occur in any animal, but most common in small
breed dogs
 Problems:
1. Interfere with normal eruption pathway of permanent
teeth  malocclusion

Early detection is key!
2. Are a reservoir for debris  dental disease


Extraction is almost always necessary
Referred to as Interceptive Orthodontics
Persistent Deciduous Canine Teeth
*Note:
deciduous teeth
are numbered
differently in
the Triadan
system
(500, 600, 700,
800)
Polydontia
 Supernumerary teeth should not be confused with
retained deciduous teeth.

These are extra ___________ 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
Can differentiate adult vs.
deciduous via radiographs
Hypodontia
 One or more teeth do not form in the dental arcade.
 Un-errupted permanent tooth or hypodontia?
 How do you confirm?
 If permanent tooth is absent, a deciduous tooth can
remain in the arch for months to years.
 No treatment necessary