L88: Development of the Dentition

Question 1

What is orthodontics?

Answer 1

The branch of dentistry concerned with:

• facial growth;
• development of the dentition;
• occlusion;
• and with the diagnosis, interception and treatment of occlusal anomalies.

Question 2

What are the stages of development of the dentition?

Answer 2

• Newborn;
• Primary (deciduous);
• Mixed;
• Permanent.

Question 3

What are the features of a newborn dentition?

Answer 3

• Gum pads;
• Upper - rounded, lower - U-shaped;
• Appear skeletal class 2 (chin back).

Question 4

What is a skeletal class 1 antero/posterior (AP) jaw relationship?

Answer 4

Mandible is 2-3mm posterior to the maxilla

Question 5

What is a skeletal class 2 antero/posterior (AP) jaw relationship?

Answer 5

Mandible is retruded relative to the maxilla

Question 6

What is a skeletal class 3 antero/posterior (AP) jaw relationship?

Answer 6

Mandible is protruded relative to the maxilla

Question 7

What is the name of a tooth that is present at, or just after, birth?

Answer 7

A natal tooth

Question 8

What is the typical age range for the primary dentition to erupt?

Answer 8

6 months - 3 years

Question 9

In a primary dentition, do the lower or upper teeth erupt first? (typically)

Answer 9

Lower

Question 10

What is the typical eruption pattern for the primary dentition?

Answer 10

a-b-d-c-e

Question 11

What are three typical features of the primary dentition?

Answer 11

• Incisors are more upright than the permanent dentition;
• Spaced (>6mm);
• Worn towards the end of their lifespan.

Question 12

A primary dentition with little or no spacing are prone to…

Answer 12

overcrowding permanent teeth.

Question 13

At what age do you typically find a mixed dentition?

Answer 13

Age 6-13

Question 14

What are the first permanent teeth to erupt and at what age?

Answer 14

First molars and incisors, 6-8.5 y/o.

Question 15

At what age do the canines, premolars and second molars erupt?

Answer 15

10-12.5 y/o

Question 16

Do the lower or upper 6’s erupt first? (typically)

Answer 16

Lower

Question 17

What are two typical features of the permanent dentition?

Answer 17

• Incisors are wider than deciduous teeth, hence the need for spaces in the primary dentition;
• Teeth are less upright, and more proclined.

Question 18

What is the typical time between pairs of teeth, e.g. central incisors, erupting?

Answer 18

6 months, i.e. is 11 erupts on 01/01, 21 should have erupted by 01/07, otherwise this could indicate a problem.

Question 19

In a mixed dentition, do central or lateral incisors erupt first?

Answer 19

Central

Question 20

What are additional teeth, to the normal series, called?

Answer 20

Supernumary

Question 21

What is the term used for larger, than normal, teeth?

Answer 21

Macrodont

Question 22

What is the term used for smaller, than normal, teeth?

Answer 22

Microdont

Question 23

What is the typical eruption pattern for permanent canines and premolars?

Answer 23

• Lower: 3, 4, 5;

- Upper: 4, 5, 3.

Question 24

What is the overall typical eruption pattern for permanent teeth?

Answer 24

Lower: 6-1-2-3-4-5;
Upper: 6-1-2-4-5-3.

Question 25

How does the mouth accommodate for more teeth in the permanent dentition than in the primary dentition?

Answer 25

Increase/ growth in arc length posterior to the first molar. (N.B. No growth of the arc in front of this).

Question 26

What is the term for spacing in between primary teeth?

Answer 26

Leeway Space

Question 27

What is transposition?

Answer 27

The term used to describe the interchange in position of two teeth e.g. 3 and 4.

Question 28

What is an ectopic tooth?

Answer 28

The malposition of a permanent tooth bud resulting in eruption of the tooth in the wrong place, e.g. at the roof of the mouth.

Question 29

What are the six typical features of an ideal permanent dentition?

Answer 29

- Incisors slightly proclined, overjet ~2-4mm; - The mesiobuccal cusp of the upper permanent molar occludes with the buccal groove of the mandibular first molar; - Long axis of the teeth have a slight medial inclination, except the lower incisors; - Tight approximal contacts; - Flat occlusal plane or slight curve of Spee; - The crowns of the canines back to the molars have a lingual inclination.

Question 30

What is a class I incisor classification?

Answer 30

Lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors.

Question 31

What is a class II, division 1 incisor classification?

Answer 31

- Lower central incisors lie posterior to the cingulum plateau of the upper incisors; - Upper central incisors are proclined or of average inclination; - Overjet increased.

Question 32

What is a class II, division 2 incisor classification?

Answer 32

- Lower central incisors lie posterior to the cingulum plateau of the upper incisors; - Upper central incisors are retroclined; - Minimal overjet.

Question 33

What is a class III incisor classification?

Answer 33

- Lower central incisors lie anterior to the cingulum plateau of the upper incisors; - Overjet is reversed.

Question 34

What is overjet?

Answer 34

Distance between the upper and lower incisors in the horizontal plane. 2-4mm is normal.

Question 35

What is overbite?

Answer 35

Vertical overlap of the upper and lower incisors when viewed anteriorly. One third to one half coverage of the lower incisors is normal.

Question 36

What is hypodontia?

Answer 36

Congenital absence of one or more teeth

Question 37

What is reverse overjet?

Answer 37

When the lower incisors lie anteriorly to the upper incisors

Question 38

What is malocclusion?

Answer 38

Variation from ideal occlusion which has dental health and/or psychosocial implications for the individual

Question 39

What is ideal occlusion?

Answer 39

Anatomically perfect arrangement of teeth

Question 40

What is normal occlusion?

Answer 40

Acceptable variation from ideal occlusion

Question 41

What is buccal crossbite?

Answer 41

The buccal cusps of the lower premolars and/or molars occlude buccally to the buccal cusps of the upper premolars and/or molars