Hypodontia Flashcards
What is hypodontia?
Congenital absence of one or more teeth
What is anodontia?
Complete absence of teeth
When is hypoodontia considered severe?
6 or more congenitally absent teeth
How common is hypodontia?
Approx. 6% (excl. 8s)
- 6.3% F
- 4.6% M
What is the prevalence of hypodontia in primary dentition?
0.9% (rare)
What teeth are most affected by hypodontia?
(8s)
L5s
U2s
U5s
Lower incisors
How common are missing upper lateral incisors?
- 1-2% of population
- approx. 20% of all missing teeth
- associated with ectopic canine
What is associated with missing teeth in relation to orthodontics?
Slow moving teeth
- ortho takes longer
What is the aetiology of hypodontia?
Non-syndromic
- mutations in at least 3 genes
- familial
- sporadic
Syndromic
- >100 craniofacial syndromes associated with hypodontia
- cleft lip & palate
- anhydrotic ectodermal dysplasia
Environmental
- trauma
- radiotherapy/chemotherapy
How might potential hypodontia present clinically?
- delayed or asymmetric eruption
- retained or infra-occluded decidious teeth
- absent decidious tooth
- tooth form
What is the most important thing to look out for when diagnosing potential hypodontia?
Order of eruption of teeth (is there any disorder of sequence?)
What problems can be associated with hypodontia?
- microdontia
- malformation of other teeth
- short root anomaly
- impaction
- delayed formation and/or malposition of other teeth
- maxillary canine/first molar transposition
- taurodontism (long pulp chamber, flow is below CEJ)
- enamel hypoplasia
- altered craniofacial growth
What issues can hypodontia directly cause?
- spacing
- drifting
- over-eruption
- anaesthetic impairment
- functional problems
List the hypodontia care pathway:
- GDP recognition
- referral to specialist orthodontist
- in GDH
In which teeth is taurodontism most common/most difficult?
7s
What special investigations may you require in a patient with hypodontia?
- study models
- planning models
- radiographs
- photographs
- conebeam CT
What treatment options are available for hypodontia of upper lateral incisors?
- accept
- restorative alone
- orthodontics alone
- combined ortho & restorative treatment
What size are lateral incisors roughly?
6.5-7mm
What size are central- incisors roughly?
9mm
What restorative options are available for treatment of missing upper laterals where the space is open?
- resin bonded bridge
- implant
- partial denture
- auto-transplantation
- conventional bridgework
What tooth is the ideal abutment for a resin bonded bridge?
canine
What is key to successful management?
- inter-disciplinary team
- joint assessment and treatment planning with precise aims
- joint collaboration at transitional stages of treatment
What are the advantages of resin bonded bridges?
- simple
- can do when pt is young
- non-destructive
- can look good
- place on semi-permanent basis
What are the disadvantages of resin bonded bridges?
- high failure rate
- appearance sometimes not good
- orthodontic retention needs are high
- predictable aesthetics
Why is a cone-beam CT useful for restorative dentists sometimes?
You are able to assess the volume of alveolar bone present (cannot do this with regular plain film)
Why does a high smile line make restorative dentistry difficult?
Unforgiving gingival margins, hard to hide restorations etc.
In a patient with one missing lateral incisor, how could you treat the patient without orthodontics?
Camouflage
- composite on 3 to mimic adjacent lateral
- cuspal reduction of 3
- bleaching of 3 to mimic adjacent lateral
Why might an RPD be a good option for hypodontia patients?
- able to replace multiple missing teeth at different sites in arch
- able to replace soft tissue
Why do RBB in a canine position have a lower survival rate compared to a RBB in a lateral position?
Canines are an important tooth in lateral excursion (eg canine guidance)
Why is a canine the ideal abutment tooth for a lateral RBB?
- long roots
- crown dimensions
- less ‘shine-through’
How much space is required for an implant to be placed in a lateral incisor position?
In excess of 6.5mm
What is a disadvantage of implant treatment in hypodontia pts?
Can’t do it until growth has ceased 21+
- if you place implant too young it will end up looking submerged as alveolus continues to grow
