Local causes of malocclusion

Question 1

List the dental causes of malocclusion

Answer 1

Tooth/tissue ratio
No of teeth
Abnormal form or position of teeth
Path of closure
Pathology

Question 2

What can tooth/tissue ratio influence?

Answer 2

Crowding and spacing

Question 3

Where is crowding more common in British adults?

Answer 3

Females and males = upper arch more common

Question 4

Aetiology of crowding?

Answer 4

Genetic

• Independent genetic control of teeth and jaws
• Evolution
• Intermixing of racial/ethnic groups

Environmental - diet

Question 5

Why has the severity of dental crowding increased?

Answer 5

Reduction of jaw size and decrease in tooth wear patterns

Question 6

Name the types of spacing

Answer 6

Generalised spacing

Localised spacing - midline diastema

Question 7

Number of teeth - what effects malocclusion?

Answer 7

Missing teeth - anodontia/hypodontia
Extra teeth - supernumerary/supplemental
Interference with normal timing

Question 8

Name a condition associated with severe hypodontia

Answer 8

Ectodermal dysplasia

Question 9

Prevalence of missing teeth?

Answer 9

3-7% of population are missing teeth - 13.6% lower 3rd molars (most common)
Least common = lower incisors
1.4x higher in females
2, 5, 8 common

Question 10

What also occurs with hypodontia?

Answer 10

Teeth are often smaller = spacing

Question 11

Prevalence of supernumerary teeth?

Answer 11

Occurs in 2% pts

Question 12

Types of extra teeth?

Answer 12

Conical (mesiodens)
Tuberculate
Supplemental

Question 13

Conical supernumerary teeth (mesiodens) features?

Answer 13

Usually between 1/1
Often erupts
Displaces other teeth

Question 14

Tuberculate supernumerary teeth features?

Answer 14

Barrel shaped
Does not usually erupt
Prevents eruption of other teeth

Question 15

Supplemental teeth features?

Answer 15

Resembles normal tooth
Occurs at end of series
Causes crowding

Question 16

Interference with normal timing due to?

Answer 16

Premature loss of teeth - primary and permanent
Retention of primary teeth
Delayed eruption of permanent teeth

Question 17

Premature loss of primary incisor effect?

Answer 17

Little effect with loss of incisor

Question 18

Premature loss of primary canine causes what?

Answer 18

Shift of centre line to extraction side

Question 19

Premature loss of 1st primary molar causes what?

Answer 19

Shift of centre line

Question 20

Premature loss of 2nd primary molar causes what?

Answer 20

1st permanent molar moves mesially
Mesial movement 1st permanent molars
Space loss greater and faster in upper arch

More common in upper arch

Question 21

Deflection of permanent teeth - how are upper laterals deflected?
How to manage?

Answer 21

Upper laterals deflected palatally

Extract primary teeth as early as possible

Question 22

Infra-occluded teeth (submerging) happens when?

Answer 22

Missing permanent tooth

Ankylosed primary tooth

Question 23

Examples of abnormal form of teeth

Answer 23

Macrodontia = big teeth
Microdontia = small teeth - common for lateral incisors - can be peg shapped

Question 24

Examples of abnormal position of teeth

Answer 24

Transposition = 2 teeth swap places - 3 and 2 can swap, 4 and 3 can swap
Impaction

Question 25

Types of path of closure?

Answer 25

``` Lateral displacement Forward displacement - instanding tooth, class III incisors ```

Question 26

What is lateral displacement?

Answer 26

Narrow upper arch = teeth do not meet correctly - posterior teeth cusp to cusp Cannot get into maximum intercuspation without shifting jaw

Question 27

What is forward displacement?

Answer 27

Instanding tooth - e.g. lateral incisor is in crossbite In RCP = pt is biting on tooth in crossbite = posterior teeth not contacting Posterior teeth only contacting when shift mandible forward Class III

Question 28

Examples of pathology relating to maloccusion?

Answer 28

Cysts e.g. dentigerous Tumours Trauma - dilaceration