Topic 8: Malocclusion Flashcards
What is occlusion
normal position of teeth when jaws are closed
what is malocclusion
misaligned teeth
What are the consequences of malocclusion
Abnormal contact with other teeth or soft tissues = discomfort + pain
Accumulation of debris + foods, periodontal pockets, PD disease, tooth loss….
Chronic pain = changes in behavior
Difficulty in mastication
how do you prevent malocclusion
Oral examination starting at initial puppy/kitten 1st visit!
AHT: during pre-consultation
what can be done about a malocclusion if detected early
Can be treated with simple extraction / crown amputation or Orthodontics tx (eg. braces, wire, buttons, elastics, acrylic plates)
what happens if a malocclusion is not detected early
may result in permanent teeth malocclusions
that require extensive extractions
or multiple-procedure orthodontics.
describe the normal occlusion of dogs
Wild phenotype of domestic dogs and cats has interdigitating teeth cheek that create pinking shears effect.
describe the pinking shears effect on canines
a mandibular tooth (canine) that interdigitates with the maxillary 3rd incisor and canine (fits in the diasthema) (canine interlock)
describe the pinking shears effect on incisors
mandibular incisors that rest on the cingulae of the maxillary incissors
what are the 4 points to evaluate occlusion in dogs
Scissor incisor relationship
The canine interlock
The PM interdigitation (“pinking shear” effect)
Head symmetry
describe incisor scissor occlusion
scissor bite incisors. the mandibular incisors rest on the cingulae
describe the proper canine interlock
Mandibular canine fits into diasthema between maxillary 3rd incisor and upper canine
Not touching each other
Creates an interlock situation that prevents one or the other jaw from overgrowing the other.
what is a diasthema
space or gap between 2 teeth
describe the normal canine PM interdigitation
Cusp tips of PM should point to the interdental space
Pinking shear effect
Buccal surface of the first 1st mandibular molar occludes with the palatal surface of maxillary PM4
what is a cusp
raised points on the crowns of teeth
What are the 3 dog head shapes
dolichocephalic
mesocephalic
brachycephalic
what breed of dog has a dolichocephalic head
borzoi
what breed of dog has a mesocephalic head
lab
what breed of dog has a brachycephalic head
pug
describe the head of a mesocephalic head
Mandible is shorter and less wide than maxilla
Scissor bite incisors
Maxillary incisors are rostral
Incisal tips of mandibular incisor contact cingulae of upper incisor
what is the normal dentition for a mesocephalic head
Interdigitation of canine teeth- mandibular one into diastema b/n upper 3rd incisor and upper canine, not touching either
Premolars oppose interdental space opposite arcade
Maxillary 4th PM scissors with mandibular 1st molar
how does cusp to cusp premolars happen
How does this happen?
Either mandibular prognathism (undershot) or brachygnathism (overshot)
what does prognathic mean
longer
what does brachygnathic mean
shorter
describe the dentition of a brachycephalic breed
shorter maxilla- normal mandible
Crowding and rotation upper teeth
More prone to gingival hyperplasia due to open mouth breathing
Also prone to missing teeth
describe the dentition of a dolichocephalic breed
Have longer upper jaw
Larger interdental spaces
what is a lance tooth
Or rostrally displaced maxillary canine(s)
One or both of the maxillary canine teeth deviating or pointing rostrally
what is the result of a lance tooth
Result: closed diastema space between the max 3rd incisor and max canine tooth (crowding)
what can lance tooth cause
periodontal disease
occlusal problems
area for plaque retention
how does lance tooth occur?
genetic
what breed commonly has lance tooth
sheltie
describe an anterior crossbite
reverse scissor bite of one, two or all incisors
Displaced lingual to the lowers and the rest occlude normally
what is an anterior corset considered a secondary condition to
Usually secondary to retained deciduous incisors
what is a posterior caudal crossbite
Class 1
PM + M are lingual to lower ones
(carnassial teeth are reversed)
what is a level bite
where the incisor teeth meet exactly, surface to surface
what can level bite cause
Cause abnormal wear of the incisal edges of these teeeth & even inflammation surrounding the roots
what is the common teeth crowding in toy breeds
incissors
what is the common teeth crowding in brachycephalic breeds
PM
what is brachygnathia
excessive shortness of one or both jaws
what is prognathism
abnormal profusion of one or both jaws
what is a mandibular brachygnathic bite
Upper jaw extends significantly over the lower jaw
Also called overbite
what is a mandibular prognathic bite
Also called underbite Mandibular premolars rostrally displaced Reverse scissor bite Lower incisors are rostral Mandibular canine touches 3rd incisor
what is a narrow mandible
Lower canines impinge on:
maxillary gingivae or
hard palate
…..instead of going into diasthema
what is an open bite
the teeth do not meet properly and a space is created
what is a wry bite
When one jaw quadrant grows differently from the other and symmetry is lost
Felt to be caused by one sided prognathism or brachygnathism
