Etiology of malocclusion Flashcards
Predisposing Factors to Malocclusion
(4)
*Disturbances in Embryologic Development
*Heredity (genetics)
*Functional matrix
*Traumas
*Functional matrix
(2)
*Muscular or functional disturbances
*Habits
*Traumas
(1)
*Especially mandibular fractures.
Normal skeletal relationship
* — as a reference
* Position and projection of the
upper jaw
* Position and projection of the lower
jaw
Cranial base
Types of malocclusion
* Malocclusion occurs in – dimensions
* Angle classification is based on – relationships
3
AP
Normal Occlusion:
Class 1 Malocclusion:
Class 2 Malocclusion:
Class 3 Malocclusion:
30%
50-55%
15%
1-4%
maxillary prognathism=
class 2
mandibular prognathism=
class 3
Class II
(3)
- Mandibular retrognathism
- 40% present bimaxillary retrusion
- Rarely true maxillary prognathism
Typical Skeletal class II
(4)
- Mandibular retrognathism
- Proclined upper incisors
- Deep bite
- However, multiple presentations are
possible
Cl I maloccusion
(2)
- Jaws are well aligned in the anteroposterior
dimension - Vertical and transverse dimensions are
variable.
Transverse dimension
(3)
Intermolar distance
Intercanine distance
Arch shape:
* Upper:
* Lower:
Class III
malocclusion
(4)
- Maxillary Retrognathism
- Mandibular prognatjism
- Usually a combination of the two conditions
- Vertical dimension is variable Deepbite to openbite
Prevalence of Class III malocclusions
* Depends on the population
* Southeast Asian ~
* Middle eastern ~
* Indian ~
* European ~
15%
10%
1%
1-4%
Genetics of Class III
* Focused on
mandibular prognathism
