Etiology of Malocclusion Part 1 Flashcards

1
Q

List the predisposing factors to malocclusion:

A
  1. disturbances in embryologic development
  2. heredity (genetics)
  3. functional matrix (muscular/functional disturbances & habits)
  4. traumas (especially mandibular fractures)
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2
Q

Give an example of a functional matrix that may be a predisposing factor to malocclusion: (2)

A

muscular/functional disturbances & habits

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3
Q

What trauma specifically is a predisposing factor to malocclusions?

A

Mandibular fractures

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4
Q

What three factors contribute to malocclusion?

A
  1. genetics
  2. environmental
  3. other
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5
Q

What do we use for a reference point for a normal skeletal relationship?

A

cranial base

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6
Q

We use the cranial base as a reference point for no real skeletal relationship. This includesL (2)

A
  1. position & projection of the upper jaw
  2. position & projection of the lower jaw
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7
Q

Malocclusions occur in:

A

3 dimensions

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8
Q

Angle classification is based on:

A

AP relationships

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9
Q

List the relative percentages for the following:

  • Normal occlusion
  • Class I malocclusion
  • Class II malocclusion
  • Class III malocclusion
A
  • Normal occlusion: 30%
  • Class I malocclusion: 50-55%
  • Class II malocclusion: 15%
  • Class III malocclusion: 1-4%
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10
Q

According to the intuitive theory, what is the cause of a Class I?

A

jaw WITHOUT prognathism

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11
Q

According to the intuitive theory, what is the cause of a class II?

A

maxillary prognathism

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12
Q

According to the intuitive theory, what is the cause of Class III?

A

mandibular prognathism

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13
Q

Class II malocclusion:

  • Mandibular _____
  • 40% present _____
  • Rarely ____
A
  • Mandibular retrognathism
  • Bimaxillary retrusion
  • True maxillary prognathism
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14
Q

T/F: A class II malocclusion is most commonly caused by a true maxillary prognathism

A

False- that is rare- typically caused by mandibular retrognathism

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15
Q

What percent of class II malocclusions present with bimaxillary retrusion?

A

40%

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16
Q
  • Mandibular retrognathism
  • 40% present bimaxillary retrusion
  • Rarely true maxillary prognathism
A

Class II malocclusion

17
Q

Describe a typical skeletal class II: (3)

A
  1. mandibular retrognathism
  2. proclined upper incisors
  3. deep bite
18
Q

Describe the typical bite for a skeletal class II:

19
Q

Describe the incisors for a typical skeletal class II:

A

proclined upper incisors

20
Q
  • Mandibular retrognathism
  • Proclined upper incisors
  • Deep bite

(Skeletal class?)

A

Typical skeletal class II

21
Q
  • Jaws are well aligned in the anteroposterior dimension
  • Vertical and transverse dimensions are variable
A

Class I malocclusion

22
Q

In a class I malocclusion, the jaws are well aligned in the ____ dimension, while the ____ & ___ dimensions are variable

A

anteroposterior; vertical & transverse

23
Q

Transverse dimension involves the: (3)

A
  1. intermolar distance
  2. intercanine distance
  3. arch shape
24
Q

T/F: Both the intermolar distance and inter canine distance are involved with transverse dimension

25
Class III malocclusion: - Maxillary ____ - Mandibular ____ - Usually a ____ of the two conditions - _____ dimension is variable causing a ____ to ___ bite
- maxillary retrognathism - mandibular prognathism - combination - Vertical dimesnion; deep bite to open bite
26
- Maxillary retrognathism - Mandibular prognathism - Usually, a combination of the two conditions - Vertical dimension is variable, deep bite to open bite
Class III malocclusion
27
Prevalence of class III malocclusion depends on:
the poplulation
28
List the prevalence of Class III malocclusions based on the following populations: - Southeast Asian - Middle Eastern - Indian - European
- Southeast Asian: 15% - Middle Eastern: 10% - Indian: 1% - European: 1-4%
29
Fundamentally, mandibular growth is induced by both genetic and environmental mechanism, which interact with each other to produce:
class III phenotype
30
List the components involved that contribute to the mandibular growth in a class III relationship:
1. genes 2. environment 3. condylar cartilage (acted on by genes & environment)
31
Fundamentally, mandibular growth is induced by:
both genetics and environmental mechanisms
32
What is the etiology for an open bite?
multifactorial etiologies
33
List some examples of the multifactorial etiology of an open bite: (4)
1. Transitory 2. Skeletal (genetic) 3. Neuromuscular imbalance (CP) 4. Combination sleep apnea
34
What influences the neuromuscular imbalance seen with an open bite? (2)
1. oral habits 2. anterior tongue posture
35