Aetiology of malocclusion - local causes

Question 1

What are the dental causes of malocclusion?

Answer 1

Tooth/tissue ratio
Number of teeth
Form and position of teeth

Question 2

What are the local causes of malocclusion

Answer 2

Habits
Labial frenum
Pathology

Question 3

What is meant by the tooth/tissue ratio?

Answer 3

Imbalance in the ratio of tooth a jaw size will produce crowding or spacing of the dentition

Question 4

What are the possible aetiological factors in crowding?

Answer 4

Independent genetic control of teeth and jaws
Evolution
Out breeding
Diet

Question 5

What is the % of crowding in the UK?

Answer 5

60-70%

Question 6

What are the possible effects of crowding on the dentition?

Answer 6

Overlapping and displacement
Impaction
Mesial movement of teeth

Question 7

What is generalised spacing due to?

Answer 7

Hypodontia

Small teeth/well developed arches

Question 8

What are is the congenital causes of absence of teeth?

Answer 8

Anodontia = all teeth missing 
Oligodontia = several teeth missing 
Hypodontia = Few teeth missing

Question 9

What could the missing teeth aetiology be linked to?

Answer 9

Sex-linked recessive condition of ectodermal dysplasia

Question 10

What is ectodermal dysplasia

Answer 10

Lack of sweat glands
Sebaceous glands
and hair follicles
Some degree of anodontia or malformed teeth

Question 11

How can cleft lip and palate patients have missing teeth?

Answer 11

absence of teeth to the surgery carrie dout in the region of developiing tooth germs

Question 12

What are the most common missing teeth

Answer 12

Lower 3rd molars 13.6%
Upper 3rd molars 11%
Lower second premolars 3%
Upper lateral incisors 1.8%
Upper second premolars 1.1%
Lower incisor 0.3%

Question 13

What are the effects of developmental hypodontia?

Answer 13

Form of teeth: smaller or malformed
Position of teeth: affected by the absence of teeth
Growth

Question 14

How can developmental hypodintia affect growth?

Answer 14

May affect the alveolar bone and increase the freewau space but not the rest of the mandible

Question 15

What can cause aquired loss of teeth?

Answer 15

Premature loss of deciduous teeth
Loss of permanent teeth
Retention of deciduous teeth
Delayed eruption of permanent teeth

Question 16

What are supplemental teeth? What can they result in?

Answer 16

These have a normal form and usually occur at the end of the series
Increase crowding potential of the dentition and are treated by removal of a suitable tooth

Question 17

What are the 2 types of midline supernumerary?

Answer 17

Conical

Tuberculate

Question 18

What is a conical (mesiodens)

Answer 18

Develops early - root formation coincides with the upper central incisor 
may erupt
usually displaces otherteeth
Does not delay eruption 
May be inverted

Question 19

when would you not remove the supernumerary tooth?

Answer 19

If it is very high
inverted
removal would damage other teeth

Question 20

What is a tuberculate?

Answer 20

Develops later than the upper central incisor
Does not usually erupt
Delays the eruption of the upper central incisor
Other teeth may move into the space

Question 21

Where does a tuberculate develop?

Answer 21

on the palatal ascpect of the upper central incisor

Question 22

What happens once have removed the tuberculate?

Answer 22

the other teeth often remain high when erupted and require orthodontic treatment

Question 23

What is it important to do before dealing with patients with supernumerary teeth?

Answer 23

Carry out a full orthodontic assessment

Space must be created for the permanent teeth to erupt into and any associated malocclusion must be dealt with

Question 24

What are the different shape and size of teeth?

Answer 24

Gemination
Fusion
Macrodontia
Microdontia

Question 25

What does the equilibrium theory tell us about thimb/digit/dummy sucking?

Answer 25

The force duration is more important than magnitude

Question 26

What force needs to be applied to affect the teeth significantly>

Answer 26

6 hours/day

Question 27

How many infants suck digits? What ages does this happen?

Answer 27

> 50% between 6 months and 2 years

Stopped by 4 years

Question 28

What are the long-term effects of digit sucking on the permanent dentition?

Answer 28

Flared, spaced upper incisors
Lingually inclined lower incisors (could be proclined)
Reduced overbite (or anterior open bite)
Narrowed upper arch
Habit does not affect the molar relationship

Question 29

How do you treat the problems associated with digit sucking ?

Answer 29

If the habit stops early, the overjet may reduce within 1 year, but the tongue may have adapted to the reduced overbite and prevent this closing

Question 30

What is the labial fraenum?

Answer 30

Remnant of the tecto-labial bands

Precedes (before) tooth development and transeptal fibres

Question 31

What is the labial faenum attached to at birth?

Answer 31

Papilla, migrates with eruption of the deciduous and permanent molars

Question 32

Where does the labial faenum attach?

Answer 32

To the mucosa over the labial plate but in some cases attaches to the crest of the alveolar bone before tooth eruption
The type of attachment is determined at 7 weeks IUL, when there is separation of the lip and alveolous by an invaginating lip furrow band

Question 33

What does the histology of the labial fraebum show?

Answer 33

Not muscle
Consists of vascularised collagen fibres
interrupts the transeptal fibres

Question 34

What is the effect of the labial fraenum?

Answer 34

Midline spacing, associated with large fresh fraenum

Space closure will relapse

Question 35

How do you prevent relapse of space closure due to labial fraenum?

Answer 35

Fraenectomy - not until upper laterals and canines are present (90% of diastemas close spontaneously)

Question 36

How do you diagnose the labial fraenum attachement?

Answer 36

Blanching on palatal mucosa when faenum put under tension

V-shaped notch on radiograph

Question 37

What pathology is associated with malocclusion?

Answer 37

Rare and usally self-evident
Fracture
Cyst
Neoplasm
Inflammatory condition