MIH

Question 1

What type of children are more likely to be affected by MIH?

Answer 1

Those with poor health during the first 3 years of life

Question 2

Rules for balancing/compensating 6s

Answer 2

Class I molars: compensate (balance if crowded) Class II molars: Min crowding: extract upper 6 if likely to overerupt; maintain until 7s erupt if not; no balancing Crowding: compensate if upper 6 likely to overerupt;remove before or after 7s erupted; no balancing Class III: orthodontic advice to be sought; avoid balancing and compensating

Question 3

What causes hypoplasia

Answer 3

A disruption in the secretory phase. Occurs early in development forming gross enamel surface defects and small pits and grooves

Question 3

What causes the increased sensitivity

Answer 3

1. Greater innervation in the subodontoblastic/pulp horn regions
2. Increased immune cell density
3. Increased vascularity in sensitive teeth
4. porous enamel – exposed dentine
5. Activation of A delta fibres
6. Underlying increase in c-fibre action

Question 4

Aetiology of MIH

Answer 4

1. Hypoxia of the mother/child
2. Exposure to chemicals
3. Peri-natal and neo-natal problems
4. Common childhood illnesses and medically compromised children

Question 5

What occurs in the secretory phase?

Answer 5

It defines the form of the tooth. There is the deposition of organic matrix plus small thin crystalites. There is incremental growth in thickness although it is not a continuous process

Question 5

Advantages of using SSCs for MIH

Answer 5

1. Single visit for placement
2. relatively quick and simple procedure
3. usually reduce sensitivity totally because the whole tooth is covered
4. Inexpensive compared with cast restorations
5. good retention rate

Question 5

When do you not want to XLA the 6s?

Answer 5

when there is spaced dentition

with a severe class 2/3

in hypodontia

Question 6

What does MIH stand for

Answer 6

Molar/ incisor hypomineralisation

Question 7

General management of MIH

Answer 7

1. Recognisation and review
2. Desensitisation
3. Temporisation
4. Restore
5. Extract
6. Orthodontic integration

Question 8

Restoring centrals with MIH

Answer 8

1. Microabrasion
2. Etch-bleach-seal
3. Bleach
4. Composite
5. Bleach and composite

Question 9

Prevalence of MIH

Answer 9

3.6 - 25%

Question 10

What is MIH

Answer 10

Clinically hypomineralisation of systemic origin affecting one or more of the first permanent molars and any associated and affected incisors CHRONOLOGICAL DEFECT

Question 12

Differential diagnosis of MIH

Answer 12

1. Fluorosis
2. Amelogenesis imperfecta
3. Turner tooth
4. Idiopathic hypomineralisation

Question 12

How does CPP-ACP work

Answer 12

Casein phosphopeptide - amorphous calcium phosphate. Milk derived product that remineralises teeth. It provides bioavailable calcium, phosphate and fluoride ions to the tooth

Question 13

Why does amalgam have limited use in MIH

Answer 13

It is non adhesive and therefore further post eruptive breakdown can jeprordise the filling

Question 14

Managing sensitivity associated with MIH

Answer 14

1. Repeated application of 5% sodium fluoride varnish. DURAPHAT
2. Sensitive toothpastes
3. Daily use of 0.4% stannos fluoride gels
4. GIC/ Comp restorations
5. SSC

Question 15

How effective is LA when restoring a molar with MIH

Answer 15

Teeth are more difficult to anaesthatise, often staying sensitive when normal levels of anaesthesia is given - could lead to an increase in dental fear and anxiety

Question 16

When is the best time to extract the 6s

Answer 16

Bifurcation of the 7 to prevent tipping, to allow mesial drift and to prevent rotation of the 7

This is usually at the dental age of 9

Question 17

What are the two phases of Amelogenesis

Answer 17

Secretory phase and maturation phase

Question 18

How does MIH present

Answer 18

1. Demarcated patches
2. White-brown, cream
3. Post eruptive breakdown
4. Missing 6s
5. Heavily restored, abnormal restorations
6. calculus

Question 19

What causes hypomineralisation

Answer 19

Disruption in the maturation phase. Poor mineralisation of the matrix. Occurs later in development. There is the normal thickness of enamel but dubious quality

Question 20

When do central incisors start to form?

Answer 20

3-4 months in-utero

Question 21

Is it worse to extracts 6s too early or too late?

Answer 21

Too late. 5s are less likely to tip distally compared to 7s tipping mesially. It is difficult to close space involving a 7

Question 23

Prevention of sensitivity and caries in MIH

Answer 23

Fluoride, desensitising toothpaste, CPP-ACP, fissure sealants and oral hygiene

Question 24

What does the asymmetrical distribution of MIH suggest?

Answer 24

That ameloblasts are affected at a very specific stage in the development

Question 26

Alternative terms for MIH

Answer 26

1. Cheese molars
2. Hypomineralised 6s
3. Idiopathic hypomineralisation
4. Non-fluoride hypomineralisation

Question 28

Molar restoration

Answer 28

Compostie, SSC, Gold/CoCr onlays

Question 29

What occurs in the maturation phase?

Answer 29

It establishes the quality of the tooth. You get degradation of the organic matrix, coupled with mineralisation. Ameloblasts move calcium and phosphate and the process continues post eruption. Apoptosis of the ameloblasts.

Question 30

Challenges faced by MIH

Answer 30

Patient and restorative factors.

Question 31

What happens if you XLA the 6s too late or too early

Answer 31

too early - 5 tips too late - 7 tips

Question 32

When do first permanent molars start to form and when do they calcify?

Answer 32

For after 4 months in-utero and calcify at birth

Question 33

Microscopically what do you see in MIH

Answer 33

1. Altered calcium/phosphate ratio
2. Less distinct enamel rods
3. Bacterial penetration of enamel
4. Lower hardness of enamel