M-I HYPO MINERALISATION (9)

Question 1

Define hypoplastic defect

Answer 1

Reduced bulk or thickness of enamel. Enamel never formed

Question 2

Define hypomineralisation defect

Answer 2

Disturbance of enamel formation resulting in a reduced mineral content.

Question 3

What are the two classifications of enamel defects? And what are their types?

Answer 3

Systemic and local are the two classifications of enamel defects. The types of systemic enamel defects include environmental and genetic. The types of local enamel defects include infection and trauma.

Question 4

What are the two types of ENVIRONMENTAL (PART OF SYSTEMIC CLASSIFICATION) enamel defects?

Answer 4

1) Chronological (eg MIH)
2) Generalised (eg Fluorosis)

Question 5

What are three terms used to describe enamel defects?

Answer 5

1) Demarcated
2) Diffuse
3) Hypoplastic

Question 6

What is the histological and biochemical analysis of MIH teeth?

Answer 6

1) Abnormal enamel either full thickness or inner enamel only
2) Discolouration/ breakdown associated with porosity. Becomes more porous
3) Brownish/yellow – most porous
4) Whitish/yellow – less porous
5) Carbon conc. higher in affected enamel
6) Ca/P ratio lower in porous areas
7) Hypomineralisation= Carbon content increase + Ca/P decrease

Question 7

What are the consequences of hypomineralised molars?

Answer 7

1) Undergo post-eruptive breakdown
2) Become sensitive
3) Teeth are more susceptible to dental caries and decay faster as they are softer
4) More difficult to restore
5) Early intervention required.

Question 8

List some causes of MIH:

Answer 8

-Environmental changes
-Dioxine exposure
-Chronic illness
-Low birth weight
-Childhood disease with high fever
-Antibiotics
-Chicken Pox

Question 9

MIH is assymetric- true or false?

Answer 9

True

Question 10

How do we judge the long-term prognosis of MIH in first permanent molars?

Answer 10

Look for:
-Multi-surface defect?
-Brown/yellow defects?
-Evidence post eruptive breakdown?
-Pain/sensitivity?
-Defects extending across cusps or marginal ridge?
-Caries?

Question 11

What are the indications for extraction of 1st permanent molars?

Answer 11

Ortho considerations should be taken into account:

-Class I occlusion
-Normal/reduced overbite
-Mild to mod crowding
-Minimal anterior crowding
-All permanent teeth present

Question 12

What is the appropriate timing for extraction of first permanent molars?

Answer 12

Dental age of 8-9 years for LOWER ARCH.
Timing is less critical for UPPER ARCH, but space closure is likely if extracted before 11/12 years.

Question 13

Explain compensating extractions between the upper and lower 6s extraction.

Answer 13

Compensate the removal of lower 6 by removing upper 6 but DO NOT compensate the removal of upper 6- DO NOT extract lower 6!

This is because the upper 6 would over-erupt if the lower 6 is extracted due to poor prognosis. BUT the lower 6 would not over-erupt in the same way if the upper 6 was extracted due to poor prognosis.

Question 14

What are the different tx options for conservation/restoration of the teeth if deemed appropriate?

Answer 14

• Tooth Mousse
• Fissure Sealants
• Amalgam
• GIC
• Composite
• SSCs
• Onlays

Question 15

What component does tooth mousse contain?

Answer 15

Recaldent (Casein phosphopeptide-amorphous calcium phosphate… a special milk-derived protein that has a unique ability to release bio-available calcium and phosphate to tooth surfaces).

Question 16

When do we apply fissure sealants?

Answer 16

-Enamel is intact and good hardness
-No sensitivity
-No caries seen on BWs

Question 17

Is amalgam a suitable material to use to restore teeth that are broken down from MIH? Why?

Answer 17

No.

Amalgam is Non-adhesive and is a poor insulator. Its non-adhesive property means it has the following issues:

-Marginal leakage
-Poor retention in large, shallow cavities. Needs mechanical retention. There’s no bond.
-No mechanical support of adjacent enamel
-No protection of remaining tooth structure.
-Lots of marginal leakage and ditching

Question 18

What are the properties that make GIC a suitable temporary restoration? What makes it an unsuitable permanent restoration material?

Answer 18

Suitable temp restoration material properties:
-Adhesive
-Fluoride release
-Good insulator

Unsuitable permanent restoration material property:
-Poor wear resistance

Question 19

When should composite be used and not used for enamel defects?

Answer 19

To be used if:
1) well demarcated defects confined to 1 or 2 surfaces
2) no cusp involvement
3) margins preferable supragingival

Not to be used if:
1) defects involving cusps or multiple surfaces
2) poorly demarcated defects
3) significant sensitivity

Question 20

What are indications for the use of SSC in MIH molars?

Answer 20

• Extensive defects
• Maintenance of severely affected tooth
• Sensitivity

Question 21

What are the advantages and disadvantages of SSC?

Answer 21

ADV:
1-Effective protection of tooth tissue
2-Prevents further deterioration
3-Eliminates sensitivity

DISADV:
1-Requires approximal and occlusal prep
2-Commits tooth to full coverage restoration
3-Subgingival, poorly adapted margin
4-Prone to wear
5-Can make tooth look better than it is
6-Poor aesthetics

Question 22

What is the most suitable method for restoring incisors with MIH?

Answer 22

Composite veneers (+/- microabrasion)