Ortho- Interceptive orthodontics

Question 1

Discuss spacing in deciduous teeth.

Answer 1

We want spacing to prevent crowding

no spacing= 66% chance of crowding.

<3mm spacing= 50% chance of crowding.

3-6mm spacing= 20% chance of crowding.

> 6mm spacing= no crowding

Question 2

What is the Leeway space?

Answer 2

This is the difference between cde and 3,4,5.

1.5mm in the maxilla.
2.5mm in the mandible.

At age 9- there should be a minimum of 18.5mm from the lateral incisor to the first molar to have enough space for the premolars and canines (otherwise crowding)

Question 3

How much can crowding improve in the mixed dentition?

Answer 3

For up to 3mm

Question 4

What is the ugly duckling stage?

Answer 4

This is when we have

• distally ponted lateral incisors- caused by the unerupted upper canines on the LI roots. (Eruption of the canines should fix this)
• Diastema

Question 5

What size of diastema can be closed by eruption of the canines.

Answer 5

A gap <2.5mm.

Question 6

What are we looking for to justify interceptive orthodontics?

Answer 6

Sequence (have the teeth errupted out of sequence)

Symmetry (has the contralateral tooth erupted within 6 months)

Supernumerary (is there an extra tooth blocking eruption? )

Question 7

List some problems we can intercept using interceptive orthodontics?

Answer 7

unerupted central incisors
Early loss of deciduous teeth
Loss of 1st molars due to caries
Crossbites
Habits
Impacted first permanent molars
Retained deciduous teeth
Infra-occluded desciduous teeth
Ectopic canines
Deep overbite
Overjet
Upper midline diastema
Supernumerary teeth

Question 8

List some causes of unerupted central incisors?

Answer 8

• Supernumeraries
• Trauma/dilaceration (trauma has caused a bend)
• Pathology.

Question 9

How do we use interceptive orthodontics for an unerupted central incisor?

Answer 9

If it is unerupted due to a supernumerary:
1. Remove the deciduous tooth and the supernumerary.
2. Expose the permanent tooth
3. Create space.
4. Monitor

These teeth should erupt within 1.5-2 years

Question 10

How does early loss of a deciduous tooth affect our treatment of the patient?

Answer 10

Early loss of Es causes major space loss and is the main cause of impacted 5s.

We treat-
As & Bs- no need to balance or compensate.
Cs- Balance (Risk of midline shift)
Ds- risk of centreline shift but less than Cs)
Es- do not balance- loss of Es causes major space loss (Greater loss in the upper than the lower)

Question 11

Why do we want to intercept patients with carious 1st molars and how do we use interceptive orthodontics for this?

Answer 11

Treatment
If extracting lower- extract upper (as without the lower, the upper would overerupt)
If extracting the upper- no need to extract the lower
Don’t balance (unless lower arch crowding)

Ideally we want to extract them after formation of the bifurcation region of 7 (age 8-9) and when the 8s are present.

Why-
We cannot keep them if they’re poor prognosis.
But early loss can cause distal migration of 5.
Late loss can cause mesial tipping & lingual rolling of the 7 with poor space closure.

Question 12

Why do we want to intercept patients with an anterior crossbite and how do we use interceptive orthodontics to treat this?

Answer 12

Problems:
* Toothwear
* Gingival recession- Lower incisor is pushed forward out of the alveolar bone)
* Mandibular closure- crossbite interferes and there may be displacement.
* The jiggling type trauma can lead to tooth mobility.

Treatment:
Correct with a URA
Favourable features for correction using a URA:
-Palatally tipped tooth in crossbite.
-Good overbite to aid stability.
-Adequate space to move the tooth forward.

Question 13

Why do we want to intercept patients with a posterior unilateral crossbite and how do we do this?

Answer 13

Problems:
Mandibular displacement
Facial asymmetry
Teeth may erupt in displaced ICP positions.
50% chance of relapse.

Treatment
Maxillary expansion with a URA or quadhelix.

Question 14

Patient sucks their thumb. How can we use interceptive orthodontics to treat this?

Answer 14

Using a A removable habit breaker- Get the patient to wear it every day for 1-2 months. This should break the habit.
You then wait 6 months for any other eruptions and reassess.

You can use an URA or quadhelix for maxillary expansion to treat the unilateral crossbite.

Question 15

Why do we want to intercept patients with impacted first permanent molars and how do we do this?

Answer 15

Can cause pulpitis of the E or premature exfoliation.
We treat this by:
* -Observing for 6 months (65% will disimpact by age 7)
* -Extract the E- regain space for the premolar or treat crowding at a later stage.
* Disimpact-
Separators
- Disc the distal of the E
- Band the E and bracket the 6 using an open coil.
- URA with finger spring an attachment on the 6.

Question 16

Why do we want to intercept patients with retained deciduous teeth and how do we do this?

Answer 16

Why- They block the way for adult teeth to erupt.
How- If there is an unerupted permanent tooth then extract the desciduous tooth when the permanent root is 1/2 to 1/3 developed.

Question 17

What do we need to consider when treatment planning the interception of infra-occluded deciduous teeth and how do we treat this?

Answer 17

Clinically:
-Visually- Can we see the infraoccluded tooth.
-Percussion-does it make a dull cracked cusp sound when you tap it?
-Radiographically- is there a permanent successor?

Treatment-
If there is a permanent successor observe for a year to see if it erupts.
If there is not- extract the tooth.
If there is <1mm of supragingival crown height- extract the tooth.

Question 18

How do we assess an ectopic upper canine?

Answer 18

Buccal palpatation from the age of 9.
Mobility test of the Cs- due to resorption if the 3s are in the right place.
Radiographically-
How high is the canine?
How much of the adjacent incisor does it overlap?
What angle do they make- we want an angle <30*.

Question 19

How can we treat an ectopic upper canine through orthodontic interception?

Answer 19

Extraction of the C- This works until the patient is 13.

If there is crowding a passive URA is used for space maintenance.

Question 20

Why do we want to intercept a deep overbite and how do we intercept this orthodontically?

Answer 20

Problems:
Gingival stripping
Palatal ulceration.

Treatment:
URA with a flat anterior bite plane.

Question 21

Why do we want to intercept a class III reverse/reduced overjet and how do we intercept this orthodontically?

Answer 21

Problems
* Aesthetic
* Difficulty eating (not occluding)
* Displacement on closure
* Incisial edge wear
*
Treatment:
Camoflauge- accept the skeletal base but give them a class I incisal relationship.
Maxillary protraction- growth modification using reverse pull headgear.

Question 22

Why do we want to intercept a class II overjet and how do we intercept this orthodontically?

Answer 22

URA to retract the upper incisors
Functional appliance (posturing the patient forward)

Question 23

In what situation can we intercept an overjet with a URA and why?

Answer 23

If the patient can achieve an edge to edge bite.
If the upper incisors are <120 degrees and lowers are >80 degrees then we have space to move the teeth back.

Question 24

Why would we want to intercept an upper midline diastema and how can we treat this with interceptive orthodontics?

Answer 24

Problem: Aesthetics

Treatment- Early closure and a bonded retainer if severe.
If it is caused by supernumeraries we could extract but think about risk v benefit.

Question 25

Why would we want to intercept supernumerary teeth and how can we treat this using interceptive orthodontics.

Answer 25

Problem- they block eruption.

Conical- extract if erupted or impeding tooth movement
Tuberculate- extract as they are preventing eruption.
Supplemental-tend to extract based on toothform and position

Question 26

How do we treat lower ectopic canines interceptively?

Answer 26

• Extraction of the ectopic tooth (65-90%)
• Extraction of the C & expose with Orthodontic movement into the space

If there is crowding we want to space maintain using a lingual holding arch.