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Ortho > hypodontia > Flashcards

hypodontia Flashcards

1
Q

definition

A

congenital absence of one of more teeth (excluding third molars)

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2
Q

anodontia

A

complete absence of teeth

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3
Q

severe hypodontia/oligodontia

A

6 or more congenitally absent teeth

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4
Q

prevalence of hypodontia

A

around 6% excluding 8s

6.3% F, 4.6% M in European pop

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5
Q

prevalence of hypodontia in primary dentition

A

0.9%

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6
Q

most affected teeth

A

L5s, U2s, U5s, L incisors
excluding 8s
U1s hardly ever missing

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7
Q

missing U2s prevalence

A

1-2% pop

around 20% of all missing teeth

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8
Q

what are missing U2s associated with?

A

ectopic canines

esp palatally - don’t have guiding effect of U2 root - drifts mesially and gets tucked behind 1

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9
Q

broad etiological categoriesx3

A

multifactorial

  • non-syndromic
  • syndromic
  • environmental
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10
Q

non-syndromic aetiology

A

mutations in at least 3 genes associated with missing teeth in non-syndromic hypodontia
familial
sporadic

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11
Q

syndromic aetiology

A 
>100 craniofacial syndromes associated with hypodontia
CLP
Van der Woude syndrome
Down syndrome
anhydrotic ectodermal dysplasia
 - ectoderm doesn't develop properly
 - lack of sweat glands and body hair, severe              
   hypodontia, v thin wispy blonde hair
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12
Q

environmental aetiology

A

trauma
radiotherapy/chemotherapy

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13
Q

presentation

A
  • delayed or asymmetric eruption
  • retained or infra-occluded deciduous teeth
  • absent deciduous tooth
    • if primary tooth missing permanent likely to be too as permanent tooth germ develops from the primary tooth germ
  • tooth form
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14
Q

what should you do if you suspect hypodontia?

A

refer early

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15
Q

main associated problem x1

A

microdontia

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16
Q

associated problems

A 
microdontia
malformation of other teeth
short root anomaly
impaction (esp U3)
delayed formation and/or delayed eruption of other teeth
crowding and/or malposition of other teeth
U3/4 transposition
taurodontism
enamel hypoplasia
altered CF growth
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17
Q

taurodontism

A

elongated pulp chambers

18
Q

potential problems

A 
spacing
drifting
over-eruption
aesthetic impairment
fct problems (less common as PC)
Deep OB/ reduced LFH
19
Q

hypodontia care pathway

A

GDP recognition
referral to specialist orthodontist
in GDH - initial assessment in ortho and allocate when appropriate to a hypodontia clinic (ortho and Rx input)

20
Q

keys to successful management

A 
interdisciplinary team (joint appt)
joint assessment and tx planning with precise aims
joint collaboration at transitional stages of tx
follow up of treated cases - learn what is best and deal with any problems as they arise
21
Q

assessment and planning

A 
history
EO exam
IO exam
 - orthodontic aspects
 - restorative aspects
investigations
problem list
definitive plan
retention/maintenance
22
Q

investigations

A 
study models
planning models - kesling, diagnostic
 - simulate tooth movement
 - planning
 - show pt what could potentially be achieved
radiographs - often OPT +/- other IOs
photographs
CBCT
23
Q

missing U2s - options

A

accept
restorative alone
ortho alone
combined ortho and restorative (most common)

24
Q

basic options for combined treatment

A

open space
close space

25
Q

opening space

A

implant
autotransplantation e.g. crowded premolar in palate
RBB
conventional bridgework - a bit destructive
RPD / overdenture

26
Q

close space types x2

A
  • simple - ortho used just to close space
  • space closure plus
    • close space ortho
    • position teeth in a way to make Rx work easier
    • Rx tx
27
Q

plan of choice should:

A

satisfy expected aesthetic objectives
least invasive
satisfies expected functional objectives
- immediate
- long-term (65+ years)

28
Q

in case of missing U2, why retracting canines for RBB needed

A

canine often erupts next to central if retained c as pushes it to erupt where lateral missing

29
Q

retention after retracting canines

A
  • high relapse potential if have retracted canine a lot or if rotated
  • RBB ends up buccally outside line of arch if insufficient retention
  • often need TAD (temporary anchorage device)
30
Q

which bridge design has better success?

A

cantilever design

  • less failure if debond
  • but more relapse potential
31
Q

RBB ideal abutment

A

canine

  • less shine through of metal wing
  • root length
  • crown dimensions
  • (but) might fail due to canine guidance/ excursion movement
32
Q

advantages of RBB

A 
relatively simple (short timescale)
do when young (complete tx)
non-destructive
can look good
place on semi-permanent basis (e.g. if future implant)
33
Q

disadvantages of RBB

A 
technique sensitive - operator important
failure rate
appearance sometimes not good (try again, new materials)
ortho retention needs are high
maintenance
34
Q

opening space for implant

A
  • retract canine to give 7mm space at level of gingival margin
  • can give retainer with prosthetic tooth until can get implant
  • leave good quality bone
  • need roots at correct angulation
  • stands alone - doesn’t stress other teeth
  • CBCT
35
Q

RBB vs implant: key differences

A

cant do implant until at least 21-23yo (later for M)
- pts grow vertically esp in anterior region
need min 7mm space
root separation
often need bone graft
technically v demanding in aesthetic zone
- can get recession and metal shine through
significant extra time to do
significant cost

36
Q

factors for simple space closure

A

tooth shape/size
tooth colour - canines can be yellowy
gingival architecture - central and canine higher, lateral lower

37
Q

how to make a canine look like a lateral

A

individualised extrusion of canine re gingival contour height relative to U1
significant reshape
- do gradually so as not to threaten pulp
bleaching - can use bleaching tray as retainer

38
Q

how to make a first premolar look like a canine

A

intrude U4 to give correct gingival architecture
Rotate mesially to take up more space and so you don’t see palatal cusp
composite build up or veneer U4 to restore vertical height and “caninise” it

39
Q

space closure advantages

A

no prosthesis - relatively low maintenance
good aesthetics with appropriate ortho and Rx techniques
can be done at an early age

40
Q

When to refer

A
  • abnormality in eruption sequence/ > 6mo diff of contra lateral
  • complete absence of space
  • severely infraoccluded primary tooth

Ortho (22 decks)

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