When the Mixed Dentition Period Begins: Quiz and Flashcards

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Questions and Answers

At what age do the first permanent molars typically erupt?

6 years (correct)

8 years

4 years

10 years

What influences the anteroposterior positioning of the permanent molars?

Angulation of the premolars

Size of the canines

Spacing between the incisors

Terminal plane relationship of the deciduous molars (correct)

What role do the first permanent molars play in occlusion?

They establish and function in occlusion in permanent dentition (correct)

They guide the eruption of the incisors

They maintain the alignment of the premolars

They are responsible for canine guidance

How does a flush terminal plane of the second deciduous molars influence the eruption of the permanent first molars?

It leads to a Class I molar relationship immediately Signup and view all the answers

What is the role of the Leeway space in the development of occlusion?

It allows for mesial shift of the permanent first molar Signup and view all the answers

During which period does the emergence of the first permanent molars and transition of incisors take place?

First transitional period Signup and view all the answers

What is the result of a distal step in the deciduous second molars?

Class II malocclusion Signup and view all the answers

What does a mesial step relationship of primary second molars lead to in the mixed dentition?

Class I molar relation Signup and view all the answers

What is the term for the early shift that occurs during the early mixed dentition period?

Early mesial shift Signup and view all the answers

What causes the closing of any spaces between the primary molars or primate spaces in a spaced arch during early shift?

Eruptive force of the permanent molars Signup and view all the answers

When does the late mesial shift of molars occur?

Late mixed dentition period Signup and view all the answers

What did Nance describe in 1947 related to the combined mesiodistal width of certain teeth?

Leeway Space Signup and view all the answers

What is the expected arch length in the maxilla based on Nance's description?

$1.8$ mm Signup and view all the answers

What is the expected arch length in the mandible based on Nance's description?

$3.4$ mm Signup and view all the answers

What contributes to class II malocclusion despite Leeway space and differential growth?

$\text{Distal step}$ Signup and view all the answers

During which phase does early shift occur?

$\text{Early mixed dentition period}$ Signup and view all the answers

Study Notes

Molar Eruption and Occlusion

First permanent molars typically erupt between 6-7 years old.

Anteroposterior Positioning of Permanent Molars

The anteroposterior positioning of permanent molars is influenced by the terminal plane of the second deciduous molars.

Role of First Permanent Molars in Occlusion

First permanent molars play a crucial role in occlusion, as they establish the posterior occlusal plane.

Influence of Terminal Plane on Permanent Molars

A flush terminal plane of the second deciduous molars allows for a more mesial eruption of the permanent first molars.

Leeway Space and Occlusion

The Leeway space contributes to the development of occlusion by providing room for the permanent teeth to erupt.

Emergence and Transition Period

The emergence of the first permanent molars and transition of incisors occur during the early mixed dentition period (6-12 years old).

Distal and Mesial Steps

A distal step in the deciduous second molars results in a Class II molar relationship.
A mesial step relationship of primary second molars leads to a Class III molar relationship in the mixed dentition.

Early and Late Shift

Early shift occurs during the early mixed dentition period, where the molars shift mesially to close any spaces between the primary molars.
The late mesial shift of molars occurs later in the mixed dentition period.

Nance's Description and Arch Length

Nance described in 1947 that the combined mesiodistal width of the primary canines and molars equals the combined mesiodistal width of the permanent canines and premolars.
The expected arch length in the maxilla is 38 mm based on Nance's description.
The expected arch length in the mandible is 34 mm based on Nance's description.

Class II Malocclusion

Class II malocclusion can occur despite Leeway space and differential growth due to other factors such as genetics, habits, or other environmental influences.