Hypodontia Flashcards
What is hypodontia?
Congenital absence of one or more teeth
What is severe hypodontia?
6 or more congenitally absent teeth
(not including 8s)
What is anodontia?
Complete absence of teeth
Which teeth are most commonly affected by hypodontia?
(in order)
(8’s), L5’s, U2’s, U5’s, lower incisors
Why are missing laterals associated with ectopic canines?
lack of guiding effect, canine can stray off
What are the aetiological factors involved in hypodontia?
Non-syndromic- caused by mutation/genetic tendency (can be familial, sporadic or de novo)
Syndromic- associated with CLP and anhydrotic ectodermal dysplasia
Environmental
-> trauma (not a cause as hypodontia is developmental)
-> radio/chemotherapy
What are the signs of hypodontia?
Big midline diastema
Infra-occlusion
Teeth not erupting/exfoliating in expected sequence
Tapered and small teeth- gives overall picture of abnormal dental development
What is guaranteed if the deciduous tooth is absent and why?
Successor will be absent
-> Permanent tooth germ develops on from primary tooth germ
Which problems are associated with hypodontia?
Microdontia- more spacing
Malformation of other teeth
Short root anomaly
Impaction
Delayed formation and/or delayed eruption other teeth
Crowding and/or malposition of other teeth
Maxillary canine/first premolar transposition
Taurodontism- enlarged pulps
Enamel hypoplasia
Altered craniofacial growth
What are the occlusal consequences of hypodontia?
Reduced OVD and increased OB
What are the signs of anhydrotic ectodermal dysplasia?
Thin hair, severe hypodontia, conical shaped teeth, lack of sweat glands
What are the potential dental problems which can result due to hypodontia?
Spacing
Drifting
Over-eruption (nothing to oppose)
Aesthetic impairment
Functional problems- issues eating in v severe cases
What are the stages of the care pathway in hypdontia cases?
GDP- recognises and refers to Ortho specialist
In GDH- first seen in Ortho then allocated to hypdontia clinic
What early intervention treatment may be used to fix a midline diastema in hypodontia patients?
- Extraction URb, ULb
- Sectional fixed appliance to close space between UR1, UL1
- Allows eruption UR3, UL3
Who is involved in the interdisciplinary team for treating hypodontia?
Restorative specialists
Orthodontic specialists
Lab technicians
Which special investigations may be helpful when assessing hypodontia patients and planning treatment?
Study Models
Planning models
-> Kesling, diagnostic
Radiographs (OPT)- account for all missing teeth, root formation, general dental health
Photographs- monitor progress
Conebeam CT- check bone volume for implant placement
Why are diagnostic wax ups helpful for hypodontia patients?
Shows patient simulation of what you hope to achieve
-> Can be used to plan where you want to move teeth to to allow space for adequate prosthetics and restorative treatments
What are the treatment options for patients with missing upper laterals?
Accept
Restorative alone- may not fully close diastema
Orthodontics alone- if slight alignment issues and satisfactory aesthetics
Combined orthodontic & restorative treatment
What are the adv/dis of accepting hypodontia
ADV
-> hypodontia scores highly on IOTN (but dental health implications are limited- easier to clean etc)
-> may still have satisfactory appearance
DIS
-> Reduction in tooth substance for mastication
-> aesthetics are often poor
What is a TAD?
Temporary anchorage device- mini bone screw
What are the combined treatment options when treating hypodontia?
Open space
-> RBB
-> Implants
-> Partial denture
-> Conventional bridgework
-> autotransplantation
Close Space
-> Simple
-> Space closure plus (aims to close gaps and make things look natural)
What are the key factors to address in the plan for combined treatment for hypdontia?
- Satisfies expected aesthetic objectives
- Least invasive
- Satisfies expected functional objectives
-> Immediate
-> Long term (65 years +)
When would space opening be opted for?
If it would be difficult to move all teeth to close space orthodontically
-> Fixed appliance can be used to redistribute space
Why are bridges not ideal in the canine region? What can be done to fill the space and combat this?
Use TAD to take canine back while keeping molars in position- creates space for lateral incisor which can be replaced prosthetically
Why is cantilever design preferred for RBB when treating missing laterals?
Prevents risk of one wing failing then caries developing underneath
Better overall success rate
What is the canine the ideal abutment for an RBB to fix missing laterals?
Long root length
Satisfactory crown dimensions
Less shine through
What are the advantages of using RBB to fix missing laterals?
Relatively simple
Can be done while patient is younger
-> can be used as place holder for implant when patient is grown
Non-destructive
Can look aesthetic
Placed on semi-permanent basis
What are the disadvantages of using RBB to fix missing laterals?
Failure- risk increases with parafunction, mobility, OB, proclination of teeth
Appearance sometimes not good, (try again, new materials)
Orthodontic retention needs are high
When may an implant be considered to fix missing laterals?
If primary canine is retained, permanent canine can be distalised (may require TAD- difficult tooth movement)
If hypodontia is assymetrical
What are the requirements for placing an implant to fit missing laterals?
7mm space at gingival level required for lateral incisor implant- use gauge to confirm (looking for regular width)
Check radiographically that roots are paralleled/separated to allow space for implant
Check bone using CT- some patients require grafting beforehand
Patient must be 18-19 before this can be considered
What can be worn by patient to fill missing space while they are undergoing implant treatment?
Pressure formed retainer with replacement tooth
Why may aesthetics be unpredictable in implant cases?
Recession of gingival margin in some cases can lead to metal work being visible
What are the main issues with implant treatment?
Often need bone graft
Technically very demanding in aesthetic zone
Significant extra time to do
Significant cost
Why may space closure be preferred to opening space?
Gets rid of risks of restorative failure and deterioration of restorations over time
In what situation would simple space closure be an option?
If canines erupted into position of laterals
-> Corners can be added to canines to make them appear more like laterals
What are the issues with simple space closure?
Gingival margin heights do not look natural
Canines often appear more yellow than the laterals would have
Canines are often bigger than laterals
What would be the aspects involved of space closure plus in treating missing laterals?
Extrude canines to allow gingival margin to follow natural architecture- reduce cusp tips
Whiten canines to fix yellowness- can be local (may also have retainer effect)
If slight crossbites develop- this can be adapted with adjusting ortho arch wire
Premolar can be intruded, leaves space to build up in composite to make it look more like a canine
Bonded retainer can be used to keep everything in place
How is space closure plus used to fix a large midline diastema?
Bring centrals together- then move canines then other posterior teeth may close space spontaneously (class 3 elastics can be used to help close space)
What are the advantages of space closure plus?
No prosthesis – relatively low maintenance
Good aesthetics with appropriate orthodontic and restorative techniques
Can be done at an early age
What are the keys to successful management of hypodontia?
Inter-disciplinary team (joint appointment)
Joint assessment and treatment planning with precise aims
Joint collaboration at transitional stages of treatment
Follow up of treated cases
-> assess aesthetics and stability
