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BDS4 Orthodontics > Hypodontia > Flashcards

Hypodontia Flashcards

1
Q

What is hypodontia?

A

Congenital absence of one or more teeth

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2
Q

What is severe hypodontia?

A

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

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3
Q

What is anodontia?

A

Complete absence of teeth

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4
Q

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

A

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

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5
Q

Why are missing laterals associated with ectopic canines?

A

lack of guiding effect, canine can stray off

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6
Q

What are the aetiological factors involved in hypodontia?

A

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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7
Q

What are the signs of hypodontia?

A

 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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8
Q

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

A

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

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9
Q

Which problems are associated with hypodontia?

A

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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10
Q

What are the occlusal consequences of hypodontia?

A

Reduced OVD and increased OB

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11
Q

What are the signs of anhydrotic ectodermal dysplasia?

A

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

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12
Q

What are the potential dental problems which can result due to hypodontia?

A

Spacing

Drifting

Over-eruption (nothing to oppose)

Aesthetic impairment

Functional problems- issues eating in v severe cases

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13
Q

What are the stages of the care pathway in hypdontia cases?

A

GDP- recognises and refers to Ortho specialist

In GDH- first seen in Ortho then allocated to hypdontia clinic

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14
Q

What early intervention treatment may be used to fix a midline diastema in hypodontia patients?

A
  1. Extraction URb, ULb
  2. Sectional fixed appliance to close space between UR1, UL1
  3. Allows eruption UR3, UL3
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15
Q

Who is involved in the interdisciplinary team for treating hypodontia?

A

Restorative specialists

Orthodontic specialists

Lab technicians

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16
Q

Which special investigations may be helpful when assessing hypodontia patients and planning treatment?

A

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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17
Q

Why are diagnostic wax ups helpful for hypodontia patients?

A

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

18
Q

What are the treatment options for patients with missing upper laterals?

A

Accept

Restorative alone- may not fully close diastema

Orthodontics alone- if slight alignment issues and satisfactory aesthetics

Combined orthodontic & restorative treatment

19
Q

What are the adv/dis of accepting hypodontia

A

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

20
Q

What is a TAD?

A

Temporary anchorage device- mini bone screw

21
Q

What are the combined treatment options when treating hypodontia?

A

Open space
-> RBB
-> Implants
-> Partial denture
-> Conventional bridgework
-> autotransplantation

Close Space
-> Simple
-> Space closure plus (aims to close gaps and make things look natural)

22
Q

What are the key factors to address in the plan for combined treatment for hypdontia?

A
  1. Satisfies expected aesthetic objectives
  2. Least invasive
  3. Satisfies expected functional objectives
    -> Immediate
    -> Long term (65 years +)
23
Q

When would space opening be opted for?

A

If it would be difficult to move all teeth to close space orthodontically
-> Fixed appliance can be used to redistribute space

24
Q

Why are bridges not ideal in the canine region? What can be done to fill the space and combat this?

A

Use TAD to take canine back while keeping molars in position- creates space for lateral incisor which can be replaced prosthetically

25
Q

Why is cantilever design preferred for RBB when treating missing laterals?

A

Prevents risk of one wing failing then caries developing underneath

Better overall success rate

26
Q

What is the canine the ideal abutment for an RBB to fix missing laterals?

A

Long root length

Satisfactory crown dimensions

Less shine through

27
Q

What are the advantages of using RBB to fix missing laterals?

A

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

28
Q

What are the disadvantages of using RBB to fix missing laterals?

A

Failure- risk increases with parafunction, mobility, OB, proclination of teeth

Appearance sometimes not good, (try again, new materials)

Orthodontic retention needs are high

29
Q

When may an implant be considered to fix missing laterals?

A

If primary canine is retained, permanent canine can be distalised (may require TAD- difficult tooth movement)

If hypodontia is assymetrical

30
Q

What are the requirements for placing an implant to fit missing laterals?

A

 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

31
Q

What can be worn by patient to fill missing space while they are undergoing implant treatment?

A

Pressure formed retainer with replacement tooth

32
Q

Why may aesthetics be unpredictable in implant cases?

A

Recession of gingival margin in some cases can lead to metal work being visible

33
Q

What are the main issues with implant treatment?

A

Often need bone graft
Technically very demanding in aesthetic zone
Significant extra time to do
Significant cost

34
Q

Why may space closure be preferred to opening space?

A

Gets rid of risks of restorative failure and deterioration of restorations over time

35
Q

In what situation would simple space closure be an option?

A

If canines erupted into position of laterals
-> Corners can be added to canines to make them appear more like laterals

36
Q

What are the issues with simple space closure?

A

Gingival margin heights do not look natural

Canines often appear more yellow than the laterals would have

Canines are often bigger than laterals

37
Q

What would be the aspects involved of space closure plus in treating missing laterals?

A

 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

38
Q

How is space closure plus used to fix a large midline diastema?

A

Bring centrals together- then move canines then other posterior teeth may close space spontaneously (class 3 elastics can be used to help close space)

39
Q

What are the advantages of space closure plus?

A

No prosthesis – relatively low maintenance

Good aesthetics with appropriate orthodontic and restorative techniques

Can be done at an early age

40
Q

What are the keys to successful management of hypodontia?

A

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

BDS4 Orthodontics (14 decks)

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