Hypodontia Flashcards by Zach Geddes

What is hypodontia?

Congenital absence of one or more teeth

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What is severe hypodontia?

6 or more congenitally absent teeth
(not including 8s)

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What is anodontia?

Complete absence of teeth

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Which teeth are most commonly affected by hypodontia?
(in order)

(8’s), L5’s, U2’s, U5’s, lower incisors

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Why are missing laterals associated with ectopic canines?

lack of guiding effect, canine can stray off

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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

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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

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What is guaranteed if the deciduous tooth is absent and why?

Successor will be absent
-> Permanent tooth germ develops on from primary tooth germ

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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

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What are the occlusal consequences of hypodontia?

Reduced OVD and increased OB

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What are the signs of anhydrotic ectodermal dysplasia?

Thin hair, severe hypodontia, conical shaped teeth, lack of sweat glands

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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

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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

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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

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Who is involved in the interdisciplinary team for treating hypodontia?

Restorative specialists

Orthodontic specialists

Lab technicians

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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

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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?

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