Molar Incisor Hypomineralisation

Question 1

What is enamel hypoplasia?

Answer 1

A quantitative deficiency of developmental defects of enamel, which usually arise from disruptions of matrix formation

Question 2

How does enamel hypoplasia manifest?

Answer 2

it may be expressed as:

Pits

Grooves

Thin enamel

Missing enamel

Question 3

How is enamel hypomineralisation different to enamel hypoplasia?

Answer 3

It is a qualitative defect of enamel.

Manifests as changes in translucency or opacity of enamel. Instead of as pits, grooves, thin enamel, or missing enamel.

Question 4

How does hypomineralisation distribute itself?

Answer 4

May be diffuse or demarcated, and coloured white, yellow, or brown.

Question 5

What is molar incisor hypomineralisation? Which teeth are affected?

Answer 5

Hypomineralisation of systemic origin affecting one, two, three, or all first permanent molars and incisors.

Sometimes secondary primary molars and tips of permanent canines are also involved

Question 6

What is the worldwide prevalence of molar incisal hypoplasia?

Answer 6

Worldwide: 2.4 - 40.2%?

Australia: 22 - 44%

NZ: 14.9 - 18.8%

Question 7

What are the pre-natal events that lead to molar incisal hypomineralisation?

Answer 7

Pre-Natal events:

Mother hypertension

Drugs during delivery

Assisted delivery / emergency caesarian

Question 8

What are the peri-natal events that lead to molar incisal hypomineralisation?

Answer 8

Peri-natal events:

Foetal distress

Oxygen deprivation

Low birth weight / high birth weight / premature birth

Question 9

What are the post natal factors that lead to MIH?

Answer 9

Post-natal factors:

Environmental toxins

Disturbances in Ca/PO4 metabolism

Prolonged use of antibiotics

Otitis media

Frequent febrile childhood illness

Respiratory disease including asthma

Genetic predisposition

Question 10

How does MIH present?

Answer 10

Demarcated enamel defects can be seen as an abnormality in the translucency of enamel.

Lots of variability in severity.

Question 11

How can severity of MIH be assessed?

Answer 11

Looking at several factors such as:

Demarcated opacities

May or may not be associated with post eruptive enamel breakdown

Symmetry (symmetrical or asymmetrical)

Colour: white, creamy yellow, yellow, yellow brown, or brown

Number of molars affected (1 to 4)

Incisors may not be affected in mild cases or minimally affected.

Sensitive to cold, heat and tooth brushing.

Question 12

How is the colour of a lesion related to the protein and mineral content?

Answer 12

Darker lesions have less mineral content.

Brown enamel has a 15 - 21 fold higher protein content than sound enamel.

White/opaque and yellow enamel has an 8x higher protein content than sound enamel.

Question 13

Which proteins are found in MIH lesions?

Answer 13

Albumin

Alpha-1-antitrypsin and antithrombin III

Question 14

How is MIH diagnosed?

Answer 14

History

Clinical examination of teeth

Radiographic examination

Associated medical conditions

Question 15

What problems can arise when trying to manage MIH?

Answer 15

Large immature pulps

Crown height reduction

Difficulty in achieving profound anaesthesia

Enamel quality may preclude good bonding

Restoration retention difficult

Dental caries may progress faster

Question 16

What are the cross-sectional features of an MIH-affected first permanent molar?

Answer 16

Hypomineralised enamel

Transition zone

Unaffected enamel.

Characterized by many indents present along the structure of the tooth.

Question 17

How can MIH be prevented?

Answer 17

Appropriate dietary advice

Use of fluoride: Fluoride tooth paste, fluoride varnish and fluoride mouthwashes.

CPP-ACP

Sugar free gums

Fissure sealants

Recall appointments

Question 18

How can sensitivity caused by MIH be managed?

Answer 18

Plaque removal

Use of fluoride

CPP-ACP

Desensitizign tooth paste

Sealing with resin

Sealing with GIC

Resin infiltration

Compomers

Question 19

How can MIH lesions be restored?

Answer 19

Resin composite

Polyacid modified composite resins (compomers

Glass ionomers

Stainless steel crowns

Cast metal restoration - Gold or semiprecious metal onlays

Porcelain fused to metal crowns

Question 20

What factors are used to decide whether to extract a tooth affected by MIH?

Answer 20

Degree and extent of hypomineralisation/hypoplasia

Post-eruptive breakdown

Sensitivity

Age and co-operation of the child

Any developing malocclusion

Number of teeth missing/present (3rd molars)

Question 21

What are the 3 main options of managing extractions?

Answer 21

Immediate extraction: Infective, severely broken down

Delay extraction to optimize eruption of surroudning teeth (7s to move into place)

Extract as part of orthodontics

Question 22

What are the contraindications for extraction?

Answer 22

Class II malocclusion

Deep bite

Lip trap

Brachyfacial type

Spacing

Question 23

How should permanent anterior teeth be managed if they have MIH?

Answer 23

Micro-abrasion (with or without bleaching)

PMMA resin

Composite veneers

Zirconia veneers/crowns

Question 24

When should first molars be extracted immediately, intermediate, or long term?

Answer 24

Immediate = severe pain/infection

Intermediate = 7s in correct position, manage sensitivity, pulp and enamel fractures

Long term = Extract as part of ortho treatment. Manage sensitivity, pulp, and enamel fractures.

Question 25

What material should be used for long term restoration of teeth with MIH?

Answer 25

Immediate: Compomer, SSC, GIC

Intermediate: SSC, Composite

Long term: Gold/metal overlay, full crowns