lecture 5 Flashcards
(18 cards)
Predisposing Factors to Malocclusion
*Disturbances in Embryologic Development
*Heredity (genetics)
*Functional matrix
*Traumas: Especially mandibular fractures.
malocclusion etiology flow chart
Normal skeletal relationship reference point
- Cranial base as a reference
- Position and projection of the upper jaw
- Position and projection of the lower jaw
Types of malocclusion
- Malocclusion occurs in 3 dimensions (4 including time)
- Angle classification is based on AP relationships
% occurrence of different occlusions
are class I malocc always simple
no, could be skeletal abnormalities present
skeletal patterns
class 2 div 1 malocc
- Mandibular retrognathism
- 40% present bimaxillary retrusion
- Rarely true maxillary prognathism
majority of class 2 cases are this
can lead to sleep apnea
class 2 div 2 malocc
only 10% cases
strong genetic component
L inclined CI and B inclined LI
Typical Skeletal class II
- Mandibular retrognathism
- Proclined upper incisors
- Deep bite
- However, multiple presentations are possible
Cl I maloccusion
- Jaws are well aligned in the anteroposterior dimension
- Vertical and transverse dimensions are variable.
Transverse dimension measurements
ntermolar distance
Intercanine distance
Arch shape
McGill ceph angles
Class III
malocclusion
- Maxillary Retrognathism- majority
- Mandibular prognatjism
- Usually a combination of the two conditions
- Vertical dimension is variable Deepbite to openbite
prevalence cl 3 malocc
- Southeast Asian
- Middle eastern
- Indian
- European
- Depends on the population
- Southeast Asian ~15%
- Middle eastern ~10%
- Indian ~1%
- European ~1-4%
Genetics of Class III
- Suggest a **polygenic **model as primary cause of Class III malocclusion
- Linkage Analysis studies
- Used to determine the chromosome loci associated
with the condition - Suggested loci: 1p22, 1p36, 3q26.2, 6q25, 11q22, 12q13, 12q23, 19p32.2
Openbite: Multifactorial Etiologies
- Transitory
- Skeletal (genetic)
- Neuromuscular imbalance (CP)
- Oral habits
- Anterior tongue posture
- Combination Sleep Apnea
which classes of malocc can openbites occur in?
all
