Hypodontia Flashcards
What is hypodontia?
Congenital absence of one or more teeth.
What is anodontia?
Complete absence of teeth.
What is classed as severe hypodontia?
Congenital absence of 6 or more teeth.
Which teeth are most affected in hypodontia?
8’s
Lower 5’s and upper 5’s
Upper 2’s
Lower incisors
Usually the last in the series.
What are some of the associated problems in hypodontia?
Microdontia
Malformation of other teeth
Short root anomaly
Impaction
Delayed formation and/or delayed eruption of other teeth
Crowding and/or malposition of other teeth
Maxillary canine/first premolar transposition
Taurodontism
Enamel hypoplasia
Entered craniofacial growth
What is the aetiology of hypodontia?
Non-syndromic- mutations in at least 3 genes associated with missing teeth in non-syndromic hypodontia.
Familial
Sporadic
Syndromic- cleft lip and palate, anhydrotic ectodermal dysplasia
Environmental- trauma, radiotherapy.chemotherapt.
What is the presentation of hypodontia?
Delayed or asymmetric eruption of teeth- disorder sequence, 6 months between the contralateral tooth erupting.
Retained or infra-occluded deciduous teeth
Absent deciduous teeth
Tooth form
What are some of the issues associated with infra-occluded teeth?
Tooth has been ankylosed to the bone but the bone has continued to grow around it- looks like the tooth is sinking.
Over-eruption of opposing teeth
Tipping of adjacent teeth- extraction more difficult and difficult for restorative work afterwards- not enough space.
Functional impairment
Aesthetic impairment
What specialists would be involved in a hypodontia case?
Orthodontics
Restorative
Paediatrics
Oral surgery
What is the hypodontia care pathway?
GDP recognition
Referral to specialist orthodontist
- initial assessment here and then MDT.
What are the keys to successful management of hypodontia cases?
Inter-disciplinary team
Joint assessment and treatment planning with precise aims
Joint collaboration at transitional stages of treatment
Follow up of treated cases
Describe the assessment and planning of hypodontia cases.
History
Extra-oral examination
Intra-oral examination- ortho and restorative aspects
Investigations
Problem list
Definitive plan
Retention/maintenance
What aspects of the intra-oral examination are important in hypodontia cases?
How big is the space that we need to restore?
Do they have a high smile line?
How big are the adjacent teeth beside the tooth you are restoring?
What investigations might be required?
Study models
Planning models- diagnostic wax up of what the teeth will look like after restorative treatment
Radiographs- OPT
Photographs
CBCT- localise ectopic teeth an determine extent of bone for implant placement
What are the management options for hypodontia cases?
Accept
Restorative alone- using composite to close a diastema
Orthodontics alone
Combined orthodontics and restorative treatment
What factors will influence the choice of treatment?
Satisfies expected aesthetic objectives
Least invasive
Satisfied expected functional objectives
What is the management options for missing laterals?
Space close
- simple space closure- close the space orthodontically and that’s it.
- Space close plus- close the space and then some amendments- tooth colour, alterations to tooth shape and size, gingival architecture- i.e. do this to canines to make them look like laterals.
What are the advantages of space closure and space closure plus?
No prosthesis- low maintenance,
Good aesthetics with appropriate ortho and restorative input
Can be done at an early age
What are the space open options?
RBB
Implant
Partial denture
Less commonly- conventional bonded bridge, auto-transplantation.
Describe the advantages and disadvantages of RRB in hypodontia cases?
Advantages
- Can be done when the patient is young
- Doesn’t involve complex surgical procedures
- Well tolerated by the patient
- Relatively simple
- Non-destructive
Disadvantages
- Need to wait 3 months before embarking on firxed pros after ortho treatment.
- placing an RBB in a canine position has a lower success rate than in a lateral position.
- lower success rate than implants.
- RPD usually required until Rob can be fitted.
- Failure rate
- Appearance sometimes not good
Why is it not advised to place a RRB in a canine position?
Canine is exposed to a lot of force during lateral excursion of the mandible
- more likely to fail.
Canine is an ideal abutment tooth to replace the lateral incisor.
Why is the canine an ideal abutment tooth for a RRB?
Large root to crown ratio, more bulbous tooth, crown dimensions, less shine through.
What are the advantages and disadvantages of an RPD in hypodontia cases?
Advantages-
- Can replace lots of teeth in the same arch
- Can be used to replace soft tissue
- Can be done immediately after treatment
- Can be done when the patient is young
Disadvantages
- might not be well tolerated
- Removable appliance, risk of falling out.
Describe the key differences between RRB and implants.
Cannot do an implant until the patient has finished growing- now 21+
Need a minimum of 7mm space- both coronary and in the bone.
Often need a bone graft
Technically very demanding in aesthetic zone
Significant cost
Significant extra time to do
Success rate is higher for implants- greater than 95%.
What would happen if you gave someone an implant that was still growing?
The implant would become ankylosed- the bone would continue to grow around it.
