Dental Directional Terminology
 Rostral refers to a structure that is closer to the front of
the head in comparison with another structure.
 Caudal describes a structure toward the back of the
head when compared to another structure.
 Vestibular describes the tooth surface facing the lips.
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Buccal if mandibular; labial if maxillary
 Facial describes vestibular surface of teeth visible from
the front (only used for incisors).
 Lingual refers to the surface of the mandibular teeth
adjacent to the tongue.
 Palatal refers to the surface of maxillary teeth adjacent
to the palate.
Dental Terminology
 Mesial refers to the portion of the tooth in line with the
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dental arcade that is closest to the most rostral portion of
the midline of the dental arch.
Distal refers to the portion of the tooth that is closest to
the most caudal portion of the midline of the dental arch.
Apical refers to a portion of the tooth closer to the apex,
or tip of the root.
Coronal refers to a structure within a location closer to
the crown of the tooth in relation to another structure.
Occlusal refers to the part of a tooth that meets with, or
occludes with, the teeth of the opposite dental arcade.
Interdental space refers to the space between each
individual tooth.
A palatal view of the dog maxilla. The midline is marked with a line, and
the mesial and distal tooth surfaces are marked with an M or D.
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.
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In normal occlusion, teeth come together in a scissors bite.
 The
mandibular canine tooth resides in the interdental
space of the upper third incisor and the upper canine
tooth.
 The upper fourth premolar tooth overlaps the lower
first molar, which together, constitute the carnassial
teeth.
Normal Occlusion
Normal scissors occlusion in a dog:
Rostral view of incisors and canine teeth
Normal Scissors Occlusion:
Lateral view of a dog skull. Premolars interdigitate toward the
opposing interdental space.
Review: Can You Name These Structures?
Malocclusion
 Malocclusion is an abnormality in the position of
the teeth.
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It can occur in any of the three head shapes, but is more
common in brachycephalic breeds.
 It is more common in dogs but also occurs in cats.
 There are four classes of malocclusions.
(Class I, II, III, and IV)
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Class I- easily fixed with orthodontic correction
Class II-IV are skeletal malocclusions due to differing jaw length
Class I: Rostral Cross-bite
 Maxillary incisors are caudal 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.
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Treat vs. not treat?
Rostral Cross-bite
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
Note: this may also be due to maxillary prognathism
(abnormally long maxilla)
 Referred to as “overshot”
 Lack of self-cleaning ability and can create painful
palate abrasions.
 Not an accepted standard
in any breed.
Maxilla is longer than
the mandible.
Mandible is longer
than the maxilla.
Class III: Mandibular Mesioclussion
 Mandibular prognathism: abnormally long
mandible, normal length maxilla
 Note: Could also be maxillary brachygnathism (not common)
 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.
Wry Mouth
 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 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
 Interfere with normal eruption pathway of
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permanent teeth  malocclusion
Are a reservoir for debris  dental disease
Early detection is key!
Common in small breed dogs
Extraction is almost always necessary
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Referred to as Interceptive Orthodontics
Persistent Deciduous Teeth
 Most permanent teeth will erupt lingual
or palatal to the deciduous teeth.
(babies in front)
 Exception: Permanent maxillary canine teeth will
erupt rostral/mesial to the deciduous canine teeth.
*Why is this significant?
Persistent Deciduous Canine Teeth
Abnormal attrition
Polydontia
 Supernumerary teeth should not be confused with
retained deciduous teeth.
 Radiographs aid in differentiation.
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How?
 Occurs in about 10% of dogs and rarely in cats.
 Unless extra tooth causes crowding, no treatment is
necessary.
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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?
Oligodontia
 Also called hypodontia
 One or more teeth (usually incisors or premolars) do
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not form in the dental arcade.
Many breeds are affected.
Unerrupted or hypodontia?
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.