Interceptive Orthodontics 1

Question 1

Describe the occlusion at birth

Answer 1

Gum pads
Upper is rounded
Lower is U shaped
Often appear class II
AOB

Question 2

When do deciduous teeth erupt

Answer 2

6 months to 2.5 years
a b d c e
Lowers before uppers

Question 3

How can the deciduous dentition be told apart from the permanent?

Answer 3

Deciduous incisors more upright
Spacing
Wear

Question 4

What is a natal/neo-natal tooth?

Answer 4

Abnormal dental development
Lower incisors most common
Tooth present at or just after birth

Question 5

When should neo-natal teeth be extracted?

Answer 5

If mobile and presents a risk of inhalation
If causing difficulty with breastfeeding

Question 6

What are the phases of tooth eruption?

Answer 6

Pre-eruptive phase - from when crown starts to form to when crown formation is complete
Eruptive phase - starts when roots start to form ends when teeth reach the occlusal plane
Post-eruptive phase - tooth movement/eruption continues as the root forms and throughout life in small increments

Question 7

Describe movement in the pre-eruptive phase

Answer 7

Developing crowns move constantly with the jaw
Small mesial and distal movements occur
Movement of crowns is contained within the bony crypts

Question 8

Describe movement in the eruptive phase?

Answer 8

Position of deciduous and permanent teeth alter due to eruption of the deciduous teeth and increase in height of the surrounding alveolar bone

Question 9

What are the 2 stages of the eruptive phase?

Answer 9

Intra-osseous
Extra-osseous

Question 10

What happens in the intra-osseous part of the eruptive phase?

Answer 10

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 - very slow
The reduced enamel epithelium fuses with the oral epithelium

Question 11

What happens in the extra-osseous part of the eruptive phase?

Answer 11

Crown tip penetrates through the epithelial layers - fast 1-2 weeks
Crown continues to move through the mucosa in an occlusal direction until it contacts the opposing tooth - slow
Environmental factors such as muscle forces from cheeks, lips and tongue help determine final tooth production

Question 12

What is the Gubernacular cord?

Answer 12

Fibres formed from the dental follicle in the periphery of the eruption pathway
Theory that this guides the teeth to erupt in the oral cavity

Question 13

Describe movement in the post-eruptive phase?

Answer 13

Movement after tooth has reached the occlusal plane
Occurs in response to increase in height of the growing alveolar bone and jaws
In response to attrition and abrasion
In response to loss of opposing teeth

Question 14

What causes teeth to erupt?

Answer 14

Likely a combo of:
Root formation
Remodelling of alveolar bone
Development of the PDL
The dental follicle modulates cellular activity and controls a signalling cascade

Question 15

What are some roles of the dental follicle?

Answer 15

Initiates resorption of the bone overlying the tooth
Facilitates connective tissue degradation and creates the eruption pathway
Promotes alveolar bone growth at the base of the tooth

Question 16

Describe interceptive orthodontics

Answer 16

Utilising tooth eruption to minimise the impact of a developing malocclusion
Permanent teeth can be encouraged to erupt if the deciduous tooth is extracted when there is one half to two thirds root development of the permanent tooth

Question 17

What is the definition of interceptive orthodontics?

Answer 17

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

Question 18

When is interceptive orthodontics used in the early mixed dentition?

Answer 18

Impacted 6s
Potential crowding
Early loss of deciduous teeth
Carious 6s
Cross-bites
Transposed teeth
Habits

Question 19

What are the eruption dates of the early mixed dentition?

Answer 19

6s - 6 years
1s - 7 years
2s - 8 years

Question 20

Where do the permanent incisors develop in relation to the primary teeth?

Answer 20

Palatally/lingually

Question 21

How is additional space gained for the larger anterior teeth of the permanent dentition?

Answer 21

Increase in the intercanine width through lateral growth of the jaws
The upper incisors are more proclined
The leeway space

Question 22

What is the leeway space?

Answer 22

Upper arch - primary canine first and second molas, then permanent canines first and second premolars = 1 to 1.5mm
Lower arch - primary canine, first and second molars then permanent canine, first and second premolars = 2 to 2.5mm

Question 23

What is the prevalence of diastemas?

Answer 23

6 years - 96% have diastema
12 years - 7% have diastema due to 3s erupted
If <2.5mm should close
Frenectomy has little effect on long term closure

Question 24

What are the management options of an impacted first permanent molar?

Answer 24

If patient <7 wait 6 months - 90% self correct
Orthodontic separator
Attempt to distalise the first molar
Extract E
Distal disking of E

Question 25

What can cause a central incisor to fail to erupt?

Answer 25

Supernumeraries
If patient has had trauma to primary tooth while permanent tooth is developing, causes dilaceration of root
May be other pathology

Question 26

How can unerupted central incisors be managed?

Answer 26

Remove primary teeth and supernumeraries
Create and maintain space
Monitor for 12 months if patient <9
Expose/bond gold chain and apply orthodontic traction

Question 27

What effect does early loss of deciduous teeth have?

Answer 27

Causes crowding
Localises crowding that is already present
Causes greater crowding in maxilla than mandible

Question 28

What is balancing extraction?

Answer 28

The removal of a tooth from the opposite side of the arch
This maintains the position of the dental centreline and preserves symmetry

Question 29

What is compensating extraction?

Answer 29

The removal of a tooth from the opposing quadrant
This maintains the buccal occlusion

Question 30

How can early loss of deciduous teeth be managed?

Answer 30

Loss of A and B have little impact
Cs - balance
Ds - small shift so could balance under GA
Es - consider space maintainer

Question 31

Describe a removable space maintainer?

Answer 31

Passive URA
Adam’s clasp on first molars
Labial bow or Southend clasps on anterior teeth
Acrylic baseplate
May have a mesial stop on individual teeth to stop drift (0.6mm HSSW)

Question 32

Describe a fixed space maintainer

Answer 32

Palatal and lingual arches
or
Band and loop appliance

Question 33

When should first molars be assessed?

Answer 33

8-9 years

Question 34

How are first molars of poor prognosis managed?

Answer 34

Extraction decision based on:
Age and stage of dental development
Degree of crowding
Malocclusion type
Condition of other teeth
LA or GA?

Question 35

When is extraction of first molars most ideal?

Answer 35

If 7s bifurcation is calcifying
If 8s are present
If class 1 occlusion or reduced OB
If moderate lower crowding
If mild/moderate upper crowding

Question 36

What are the general rules for extracting 6s in a class 1 occlusion?

Answer 36

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

Question 37

What should you do when assessing a posterior unilateral cross-bite

Answer 37

Is the patient displacing their mandible as they close their teeth together
If yes then they need treatment
If IOTN is a category 4c (midline shift of >2mm)

Question 38

Describe a URA used to treat a posterior unilateral cross bite

Answer 38

Active component - Hyrax screw
Retention - no retention across midline, Adam’s clasps
Baseplate - posterior bite plane to disclude teeth

Question 39

Why should a posterior cross bite be over treated?

Answer 39

They are highly prone to relapse

Question 40

How can digit habits be managed?

Answer 40

Positive reinforcement
Bitter tasting nail varnish
Glove on hand
Elastoplast
Habit breaker appliance - fixed or removable

Question 41

Describe habit breaker appliances

Answer 41

One piece baseplate with single goal post
Design alternative to include expansion - split baseplate with expansion screw and 2 palatal goal posts

Question 42

How do you know if your patient is wearing their appliance?

Answer 42

Ask them
Did they walk in wearing it
Can they speak with it in
Are they still suffering from excess salivation
Does the appliance still fit