hypodontia Flashcards
definition
congenital absence of one of more teeth (excluding third molars)
anodontia
complete absence of teeth
severe hypodontia/oligodontia
6 or more congenitally absent teeth
prevalence of hypodontia
around 6% excluding 8s
6.3% F, 4.6% M in European pop
prevalence of hypodontia in primary dentition
0.9%
most affected teeth
L5s, U2s, U5s, L incisors
excluding 8s
U1s hardly ever missing
missing U2s prevalence
1-2% pop
around 20% of all missing teeth
what are missing U2s associated with?
ectopic canines
esp palatally - don’t have guiding effect of U2 root - drifts mesially and gets tucked behind 1
broad etiological categoriesx3
multifactorial
- non-syndromic
- syndromic
- environmental
non-syndromic aetiology
mutations in at least 3 genes associated with missing teeth in non-syndromic hypodontia
familial
sporadic
syndromic aetiology
>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
environmental aetiology
trauma
radiotherapy/chemotherapy
presentation
- 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
what should you do if you suspect hypodontia?
refer early
main associated problem x1
microdontia
associated problems
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
taurodontism
elongated pulp chambers
potential problems
spacing drifting over-eruption aesthetic impairment fct problems (less common as PC) Deep OB/ reduced LFH
hypodontia care pathway
GDP recognition
referral to specialist orthodontist
in GDH - initial assessment in ortho and allocate when appropriate to a hypodontia clinic (ortho and Rx input)
keys to successful management
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
assessment and planning
history EO exam IO exam - orthodontic aspects - restorative aspects investigations problem list definitive plan retention/maintenance
investigations
study models planning models - kesling, diagnostic - simulate tooth movement - planning - show pt what could potentially be achieved radiographs - often OPT +/- other IOs photographs CBCT
missing U2s - options
accept
restorative alone
ortho alone
combined ortho and restorative (most common)
basic options for combined treatment
open space
close space
opening space
implant
autotransplantation e.g. crowded premolar in palate
RBB
conventional bridgework - a bit destructive
RPD / overdenture
close space types x2
- 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
plan of choice should:
satisfy expected aesthetic objectives
least invasive
satisfies expected functional objectives
- immediate
- long-term (65+ years)
in case of missing U2, why retracting canines for RBB needed
canine often erupts next to central if retained c as pushes it to erupt where lateral missing
retention after retracting canines
- 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)
which bridge design has better success?
cantilever design
- less failure if debond
- but more relapse potential
RBB ideal abutment
canine
- less shine through of metal wing
- root length
- crown dimensions
- (but) might fail due to canine guidance/ excursion movement
advantages of RBB
relatively simple (short timescale) do when young (complete tx) non-destructive can look good place on semi-permanent basis (e.g. if future implant)
disadvantages of RBB
technique sensitive - operator important failure rate appearance sometimes not good (try again, new materials) ortho retention needs are high maintenance
opening space for implant
- 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
RBB vs implant: key differences
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
factors for simple space closure
tooth shape/size
tooth colour - canines can be yellowy
gingival architecture - central and canine higher, lateral lower
how to make a canine look like a lateral
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
how to make a first premolar look like a canine
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
space closure advantages
no prosthesis - relatively low maintenance
good aesthetics with appropriate ortho and Rx techniques
can be done at an early age
When to refer
- abnormality in eruption sequence/ > 6mo diff of contra lateral
- complete absence of space
- severely infraoccluded primary tooth
