Interceptive Orthodontics Flashcards
Deciduous dentition vs permanent
More upright
More spaced
More white
More worn
General pattern of eruption for deciduous teeth
ABDCE
Ideal spacing of deciduous to allow no crowding in permanent
> 6mm
Eruption dates of maxillary permanent dentition
Central - 7
Lateral - 8
Canine - 11
1st premolar - 10
2nd premolar - 10
1st molar - 6
2nd molar - 12
Eruption dates of mandibular permanent dentition
Central - 6
Lateral - 7
Canine - 9
1st premolar - 10
2nd premolar - 10
1st molar - 6
2nd molar - 12
What mm of crowding may spontaneously improve
Up to 3.5mm
Reason for crowns of laterals distally tipped
Developing canines impinging on distal aspect of lateral
What age do majority of kids have a diastema?
6
Why do only 7% have a diastema by the age of 12
> Canines come in at 11-12
> Take up more space
> Shuffle the incisors together
Course of action for sequence issues
History
Examination
Radiographs
When should the contralateral tooth erupt?
6mths
List reasons for un-erupted central incisors (4)
- Supernumeraries
- Trauma
- Dilacerations
- Cysts/tumours
Tx for un-erupted central incisors (4)
- Remove deciduous teeth + supernumeraries
-Palpate? - Expose/bond
- Create space - URA (tips teeth and makes space for central)
- Monitor 1.5yrs
What is a retained deciduous tooth
Does not exfoliate once permanent tooth erupts
Implications of a significant dilaceration (3)
Poor prognosis
Straightening = root through labial plate
Loss of vitality + XLa
List reasons for median diastema
- Small teeth
- Supernumeraries
- Hypodontia
How do missing teeth cause a median diastema
More space for the centrals to space out
List some early mixed dentition interception issues (6)
> Impacted 6s
> Crowding
> Early loss of deciduous teeth
> Carious 6s
> Xbites
> Habits
Define leeway space
Difference between CDE and 345
Maxillary
- 1.5mm wider than permanent
Mandibular
- 2.5mm wider than permanent
What is the minimum space required at 9yrs old, for premolars and canines?
18.5mm from 2d to 6m
How and when is a space requirement assessment carried out (3)
> Roughly 9yrs
> Measure from 2d to 6m
> Want 18.5mm to make room for permanent successors
Define balancing deciduous teeth
Balance by Xla contralateral tooth on other side
If you lose 16 take out 26
Define compensating deciduous teeth
Balance by XLa of opposing arch
If you lose U6 XLa L6
What does the effect of early loss of deciduous teeth depend on?
Age of loss of teeth
Space available (greater effect if crowded dentition)
Management of early loss of A+B’s
No balancing/compensating required
Management of early loss of C’s
Balance
Why do we balance C’s?
C’s retained until perm incisors erupt
Losing 1 can cause midline shift to that side (if spaced dentition = little effect)
Management of early loss of D’s
Small centreline shift (not as significant as C’s)
Perhaps balance under GA not REQUIRED
Management of early loss of E’s
No balance
Why do we not balance the loss of E’s?
Major space loss but little effect to centreline
Results in significant mesial drift which will cause crowding issues
Why does losing an E cause crowding?
E’s can be 11mm wide or more
Gap reduced by 2-4mm by mesial drift of the 6
= Less room to fit 3,4,5, causing crowding
What arch is a mesial drift a bigger issue in?
Upper
General rules for the XLa of 6s (Class I) (3)
- Compensate lower with upper to prevent over eruption
- Don’t balance with sound tooth
- If XLa upper dont need to XLa lower as don’t tend to OE as much
Why do you want to compensate a 46 with a 16? (1)
Prevent overuption
If not it will prevent mesial movement of the 2nd molar
When should 6s be XLa? (4)
> Bifurcation of 7s forming
> 5s forming
> 8s follicle forming
> Class I malocclusion
> Moderate lower/upper crowing
What issues can a 5 cause if a 6 is XLa?
Usually use the mesial part of 6 to slide up vertically
Some are distally inclined and removing the 6 can cause it to drift leading to spacing or impinge on 7
What appliance would be provided for a posterior unilateral Xbite?
Active component:
Midline screw
Retention:
Adams clasps on 4s+6s
Baseplate:
PBP
Instruction for posterior Xbite appliance?
Wear it 24/7
Turn screw 1/4 no more than 2x a week
How long can it take to correct a posterior Xbite?
6-9mths
Following this pt should wear the appliance inactivated at bed at night to prevent relapse
Effects of an anterior Xbite
Wear on incisal edge
Gingival recession
What appliance would be used for an anterior Xbite on 11?
Active component:
Z spring 21
Retention:
Double adams on E’s+6’s
Anterior retention:
Adams clasps on 11
Baseplate:
PBP
Why do we need anterior retention?
If no anterior retention the appliance will just drop down when Z is activated
Timeframe for successful anterior Xbite tx?
6-8wks
Quicker than posterior
Why do we need a PBP to tx anterior/posterior XBites?
Pt must disocclude so we can push the tooth over the bite
What are the % for relapse for an anterior/posterior Xbite
ANTERIOR
> Won’t relapse
> Once incisors over lower bite remains corrected
POSTERIOR
> 50% relapse
> Why we over-correct
What are the features of a thumb sucking habit?
> Proclined upper incisors
Retroclined lower incisors
Posterior Xbite
AOB or reduced OB
Digit sucking habit breaker tx
- Fixed habit breaker
- Removable habit breaker
- Double adams on Es+6s
What is the ideal age to get a habit sorted?
Under 10yrs - within 3yrs of eruption
What are some late mixed dentition issues? (4)
- Retained deciduous teeth
- Infraoccluded deciduous teeth
- Canines
- OJ
What is an infra-occluded tooth?
Submerged tooth below the occlusal surface
Ankylosed to bone
How do we diagnose an infra-occluded tooth?
> Visual
Percussion - dull cracked sound
Xrays
What is the treatment for a submerging molar?
> Take xrays
> If permanent successor present observe for 1yr and submerging deciduous should exfoliate
> Xla when only 1mm of crown left showing and threatens to go subgingival
Management of unerupted upper canine
- Visual - tipping of laterals + wiggle C’s for mobility
- Palpate by 9-11
- Take xray - PA/OPT
What does mobility of C show?
Means canine is resorbing the C
Which 2 radiographs would you take to demonstrate the position of an ectopic canine?
OPT + anterior maxillary occlusal
What does the chance of success for XLa of cs to help ectopic canine erupt depend on? (2)
> How high the ectopic canine is
> How much the ectopic canine overlaps the adjacent incisor
% success if ectopic canine doesn’t overlap the adjacent lateral by more than 1/2
90%
% success if ectopic canine is more than halfway over the adjacent lateral
60%
What values for incisal angulation allow some room to correct a class III relationship?
Upper - <120
Lower - >80
Why can’t we tip teeth over 120 to maxillary plane?
Gives us an OJ
Why can’t we tip teeth less than 80 to mandibular plane?
No scope to retrocline
What is camouflage tx?
Changing incisor relationship but accepting the underlying skeletal relationship
Example of growth modification functional appliances
Functional regulator
Frankel 3
What class patient would you consider for maxillary protraction?
Class 3 under 10
How does a functional appliance work?
> Promotes mandibular growth
Restrict maxillary growth
Tip top teeth back
This all reduces OJ
