Interceptive Orthodontics

Question 1

What is the eruption of deciduous teeth?

Answer 1

a-b-d-c-e
lowers before uppers

Question 2

What is the most common natal tooth present at or just after birth?
When should you extract these?

Answer 2

Lower incisors
Its mobile and presents a risk of inhalation
Its causing difficulty with breastfeeding

Question 3

What is the process of tooth eruption?

Answer 3

Pre-eruptive phase
Eruptive phase
Post-eruptive phase

Question 4

When does the pre-eruptive phase start and finish?

Answer 4

Starts when the crown starts to form and end when crown formation is complete/root formation is about to start

Question 5

When does the eruptive phase start and finish?

Answer 5

Starts as soon as the root starts to form and ends when the teeth reach the occlusal plane. Splits into intra-osseous stage and extra-osseous stage

Question 6

When does the post-eruptive phase start and finish?

Answer 6

Tooth movement/eruption continues as the root forms and throughout life in extremely small increments

Question 7

What do movements occur in response to during the eruptive phase?

Answer 7

Positional changes of neighbouring crowns
Growth of the mandible and maxilla
Resorption of the deciduous tooth roots

Question 8

What is intra-osseous growth?

Answer 8

Root formation- starts with proliferation of the epithelial root sheath and continues with the production of dentine and pulp
Movement of the developing tooth-in an occlusal or incisal direction (slow-several months)
The reduced enamel epithelium fuses with the oral epithelium

Question 9

What is extra-osseous growth?

Answer 9

Penetration of the tooth’s crown tip through the epithelial layers (fast 1-2 weeks)
The crown continues to move through the mucosa in an occlusal direction until it contacts the opposing teeth (slow-several months)
Environmental factors such as muscle forces from cheeks, lips and tongue help determine final tooth position

Question 10

How can permanent teeth be encouraged to erupt?

Answer 10

If the deciduous tooth is extracted at the correct stage (1/2 to 2/3 of root development of permanent tooth)

Question 11

What is interceptive orthodontic treatment?

Answer 11

Any procedure that will reduce or eliminate the severity of a developing malocclusion

Question 12

What are the eruption dates of permanent teeth?

Answer 12

6’s- 6 years
1’s- 7 years
2’s 8 years
4’s- 10 years
3&5’s- 11-12 years
7’s- 12-13 years
6,1,2,4,3,5,7

Question 13

What is ectopic eruption of 6’s?
What are the management options for ectopic eruption of the 6’s?

Answer 13

The permanent first molar gets stuck beneath the ‘e’ and fails to erupt
Management:
If patient is <7 years old wait 6 months (90% self correct)
Orthodontic separator
Attempt to distalise the first molar
Extract the E

Question 14

What can cause unerupted central incisors?

Answer 14

Supernumeraries
Trauma to the primary tooth results in dilaceration (abnormal bend in the root or crown of a tooth) of a permanent tooth
Other pathology
Congenital absence- rare

Question 15

How do you manage an unerupted central incisor?

Answer 15

Remove primary teeth and supernumeraries
Create space/maintain space
Monitor for 12 months
–if patient is younger than 9 they will have an immature root apex
–if patient is older than 9 there should be a mature root apex
Review after 1 year- need to ensure that there is a space maintainer present

Question 16

What can early loss of deciduous teeth cause?

Answer 16

Localised crowding
Effect varies with
–degree of crowding already present
–age

Question 17

What is a balancing extraction?
Why?

Answer 17

Removal of a tooth from the opposite side of the same arch
To maintain the position of the dental centreline (preserve symmetry)

Question 18

What is a compensating extraction?
Why?

Answer 18

Removal of a tooth from the opposing quadrant
To maintain buccal occlusion

Question 19

When is the most ideal result gained when extracting first molars with a poor prognosis?

Answer 19

7’s bifurcation calcifying
8’s present
Class I or a reduced overbite
Moderate lower crowding
Mild/moderate upper crowding

Question 20

What are the general rules for extracting 6’s in a Class I occlusion?

Answer 20

If extracting lower take upper
Don’t balance with sound tooth
Don’t balance if well aligned or spaced
If extracting upper don’t need to take lowers

Question 21

What is the management for digit sucking?

Answer 21

Positive reinforcement
Bitter-tasting nail varnish
Glove on hand, elastoplasts
Habit breaker appliance (habit deterrent)- fixed or removable

Question 22

What is the risk of doing nothing with an ankylosed primary tooth?

Answer 22

Permanent successor can become more ectopic
Infra-occlusion worsens with tipping of adjacent teeth primary tooth becomes inaccessible for extraction
Caries and periodontal disease

Question 23

What growth modification is needed for a reverse OJ?
What are the options?

Answer 23

Enhance maxillary growth and/or reduce mandibular growth
Options:
–protraction headgear +/- RME (rapid maxillary expansion)
–functional appliances e.g. reverse twin block

Question 24

Why should you treat an increased OJ early?

Answer 24

Risk of trauma- incompetent lips
Appearance- bullying/self-esteem
More difficult to achieve correction once patient has stopped growing