Hypodontia

Question 1

What is hypodontia?

Answer 1

Congenital absence of one or more teeth.

Question 2

What is anodontia?

Answer 2

Complete absence of teeth.

Question 3

What is classed as severe hypodontia?

Answer 3

Congenital absence of 6 or more teeth.

Question 4

Which teeth are most affected in hypodontia?

Answer 4

8’s
Lower 5’s and upper 5’s
Upper 2’s
Lower incisors

Usually the last in the series.

Question 5

What are some of the associated problems in hypodontia?

Answer 5

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

Question 6

What is the aetiology of hypodontia?

Answer 6

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.

Question 7

What is the presentation of hypodontia?

Answer 7

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

Question 8

What are some of the issues associated with infra-occluded teeth?

Answer 8

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

Question 9

What specialists would be involved in a hypodontia case?

Answer 9

Orthodontics
Restorative
Paediatrics
Oral surgery

Question 10

What is the hypodontia care pathway?

Answer 10

GDP recognition
Referral to specialist orthodontist
- initial assessment here and then MDT.

Question 11

What are the keys to successful management of hypodontia cases?

Answer 11

Inter-disciplinary team
Joint assessment and treatment planning with precise aims
Joint collaboration at transitional stages of treatment
Follow up of treated cases

Question 12

Describe the assessment and planning of hypodontia cases.

Answer 12

History
Extra-oral examination
Intra-oral examination- ortho and restorative aspects
Investigations
Problem list
Definitive plan
Retention/maintenance

Question 13

What aspects of the intra-oral examination are important in hypodontia cases?

Answer 13

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?

Question 14

What investigations might be required?

Answer 14

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

Question 15

What are the management options for hypodontia cases?

Answer 15

Accept

Restorative alone- using composite to close a diastema

Orthodontics alone

Combined orthodontics and restorative treatment

Question 16

What factors will influence the choice of treatment?

Answer 16

Satisfies expected aesthetic objectives
Least invasive
Satisfied expected functional objectives

Question 17

What is the management options for missing laterals?

Answer 17

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.

Question 18

What are the advantages of space closure and space closure plus?

Answer 18

No prosthesis- low maintenance,
Good aesthetics with appropriate ortho and restorative input
Can be done at an early age

Question 19

What are the space open options?

Answer 19

RBB
Implant
Partial denture

Less commonly- conventional bonded bridge, auto-transplantation.

Question 20

Describe the advantages and disadvantages of RRB in hypodontia cases?

Answer 20

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

Question 21

Why is it not advised to place a RRB in a canine position?

Answer 21

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.

Question 22

Why is the canine an ideal abutment tooth for a RRB?

Answer 22

Large root to crown ratio, more bulbous tooth, crown dimensions, less shine through.

Question 23

What are the advantages and disadvantages of an RPD in hypodontia cases?

Answer 23

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.

Question 24

Describe the key differences between RRB and implants.

Answer 24

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%.

Question 25

What would happen if you gave someone an implant that was still growing?

Answer 25

The implant would become ankylosed- the bone would continue to grow around it.