Normal Occlusion and Malocclusions Flashcards
In a “normal” occlusion, describe how the incisors should be oriented/arranged.
maxillary teeth rostral to corresponding mandibular teeth
crown cusps of mandibular incisors contact cingulum of maxillary incisors
In a “normal” occlusion, describe how the maxillary and mandibular premolars and molars should be oriented/arranged.
perfect interdigitation of upper and lower premolars and molars
maxillary and mandibular premolars do NOT contact each other, but the crown cusps of the mandibular premolars bisect the interdental spaces ROSTRAL to the corresponding premolar tooth.
crown cusps of mandibular premolars are LINGUAL to maxillary premolars.
the mesial crown cusp of maxillary fourth premolar (108 and 208) are positioned lateral to the space between the mandibular 4th premolar and mandibular 1st molar
In a “normal” occlusion, describe how the canines should be oriented/arranged.
mandibular canine inclined labially and bisects interdental space between opposing maxillary 3rd incisor and canine.
__________ is any deviation from normal occlusion. This can be due to abnormal positioning or due to symmetry or other deviations in bones that support dentition.
malocclusion
Why are malocclusions a problem?
4 reasons
- can cause trauma to the bone or tooth on tooth trauma and subsequent attrition
- discomfort and pain
- periodontal disease and tooth loss
- compromised function
What are the 4 treatment options for malocclusions?
- nothing!
- surgical extraction
- crown reduction
- orthodontic therapy (braces)
A dog presents to your clinic with retained deciduous canines. This is causing the dog to have rostrally-tipped maxillary canines. What type of malocclusion is this?
Class 1 malocclusion
Rostrally-tipped maxillary canines are also called “lance canine” or “spear tooth”. These are common in shelties and are GENETIC!
Which malocclusion type is characterized by: a normal maxilla and mandible length and occlusion, but 1+ misplaced or rotated teeth
Class 1 malocclusion
Examples are: dental crowding, rotated teeth, base narrow mandibular canines (linguoversion), rostrally-tipped maxillary canines (mesioversion), and anterior or posterior crossbite
A dog presents to your clinic and on exam, you notice that its mandibular canines are linguoverted. What specific is this malocclusion?
Class 1 malocclusion – base narrow mandibular canines
A cat presents to your clinic and you notice that the canines and premolars occlude normally, but a few of the lower incisors are in front of the upper incisors.
This is known as an anterior crossbite (malocclusion class 1).
These can be inherited, but what are these generally secondary to?
retained deciduous teeth
What breed(s) commonly have crowded or rotated teeth (class 1 mal)?
toy and brachycephalic
what can be a consequence of base narrow mandibular canines?
trauma to the palate
Is base-narrow mandibular canines genetic?
yes
What is the purpose of ball therapy?
Give a passive force orthodontic device (simple, smooth, rubber ball) to the animal and have them try to hold it in their mouth as much as possible. The most ideal time to do this is around 5 months when adult teeth are just breaking through.
This treatment helps fix the class 1 malocclusion base-narrow mandibular canines.
What is the purpose of crown reduction and vital pulp therapy in a dog with base narrow mandibular canines?
cut the crown of the mandibular canines down in order to remove the trauma on the palate.
This is usually done because extraction of healthy canines is a difficult thing to do and comes with risks.
What is inclined plane therapy?
placing a peice of specifically created plastic onto the maxillary canines tp redirect the mandibular canine in its normal position (in the interdental space between the maxillary canine and the maxillary 3rd incisor).
What are other names for rostrally tipped maxillary canines?
mesioversion
lance canine
spear tooth
Mesioversion (aka rostrally tipped maxillary canines) is genetic. What breed is this common in?
shelties.
what is the treatment for anterior crossbite?
extraction of malpositioned teeth or orthodontic devices.
___________ is when one or more posterior mandibular premolars is located buccal to its maxillary counterpart.
posterior crossbite (malocclusion class 1)
What is a class II malocclusion or mandibular distoclusion?
overbite – due to SHORT mandible.
Mandibular premolars and molars will be caudal to the normal position.
What is a class III malocclusion or mandibular mesioclussion?
underbite – due to LONGER mandible
mandibular premolars and molars are rostral to the normal position
commonly seen in shih tzus, boston terriers, pugs, boxers as a breed standard. Although its the breed standard, this does not mean it is healthy or comfortable.
What is a class IV malocclusion or wry bite?
an asymmetric skeletal malocclusion – caused by the difference in length of the 2 maxillae and mandibles.
What is the treatment for Class IV malocclusions?
early intervention to avoid “locked teeth”
extraction and/or crown reduction
