MIH

Question 1

Which cells form enamel?

Answer 1

ameloblasts

Question 2

what is the stimulus that triggers ameloblasts to form enamel ?

Answer 2

dentine deposition

Question 3

what happens when ameloblasts are triggered?

Answer 3

they secrete matrix proteins and then they become calcified to about 20% (initial calcification)

Question 4

what function change do ameloblasts go through after the matrix proteins secretion phase?

Answer 4

they secrete enzymes which remove organic component and allows full mineralisation to 99% (maturation stage)

Question 5

How does removing the organic content allow full mineralisation?

Answer 5

• the crystals are trying to expand and the organic component is takin gum loads if room and preventing the expansion (Maturation stage) = 99% mineralisation

Question 6

which three stages do we see problems occurring ?

Answer 6

1. secretion of matrix proteins
2. calcification stage
3. maturation stage

Question 7

what happens when you have a disruption during the laying down of the enamel matrix

Answer 7

HYPOPLASTIC DEFECT due to ….
- physical disruption
- less enamel matrix
- matrix will be mineralised normally but we will have less of it
- reduced bulk or thickness of enamel
- enamel never formed

Question 8

what happens if the problem occurs in early initial calcification stage or maturation stage?

Answer 8

HYPO MINERALISATION due to…
- disturbance of enamel formation therefore reduced mineral content
- less mineral in enamel therefore less calcification
- AKA hypocalcifiaction or hypo maturation

Question 9

how can enamel defects be classified?

Answer 9

systemic or local

Question 10

List the different ways in which we can get local enamel defects.

Answer 10

• trauma
• infection

Question 11

list the different ways which we can get systemic enamel defects.

Answer 11

• environmental
• genetic = amelogenic imperfecta

Question 12

what can environmental defects be further classified into?

Answer 12

1. CHRONOLOGICAL = this defect has occurred at a very specific point in time as that enamel forms therefore specific teeth are affected. eg. MIH
2. GENERALISED = the insult has been there for a longer amount of time eg. fluorosis

Question 13

how can we describe enamel defects? (3)

Answer 13

1. DEMARCATED = distinct, clear boundary, yellow, white or brown
2. DIFFUSE = no clear boundary; lines patches
3. HYPOPLASTIC = loss of enamel, pits and grooves

Question 14

Give an eg of demarcated defects?

Answer 14

MIH

Question 15

give an eg of diffuse defects?

Answer 15

fluorosis

Question 16

Give eg of hypoplastic defects?

Answer 16

localised legions

Question 17

give an eg of a condition which have all 3 defects ?

Answer 17

ameleogensis imperfecta

Question 18

define MIH?

Answer 18

hypo mineralisation of systemic origin of one or more first permanent molars as well as affected incisors

Question 19

what 2 things are we looking for when diagnosing MIH?

Answer 19

demarcation
first permanent molars

Question 20

what are some other terms for MIH?

Answer 20

1. molar hypomineralisation (MH)
2. incisor hypominerlisation (IH)
3. deciduous molar hypomineralisation (DMH) (ppl use this term as second primary molars can be affected)

Question 21

list some histological and biochemical analysis of MIH

Answer 21

• abnormal enamel either full thickness or inner enamel only
• discolouration/ breakdown associated with porosity = MOST porous
• brownish/ yellow - LESS porous
• carbon concentration higher in affected enamel

Question 22

why Is it important to identify hypo mineralised molars ? (5)

Answer 22

1. these teeth go thru POST ERUPTIVE BREAK DOWN
2. SENSITIVE
3. softer so more susceptible to CARIES
4. DECAY FASTER
5. DIFICULT TO RESTORE

Question 23

Prevalence of MIH?

Answer 23

5-25% in uk

Question 24

what disruption may be the cause of MIH?

Answer 24

ameloblast disruption

Question 25

how do we treat?

Answer 25

1. start with molars 2. what is the long term prognosis

Question 26

how do we judge long term prognosis

Answer 26

Question 27

what orthodontic considerations do we need to think about when extracting MIH teeth?

Answer 27

Question 28

why is timing important when extracting MIH teeth?

Answer 28

- if we extract at the right time and right age = gives us best chance of the second permanent molars moving forward in to that space - lower arch = if we take 6 out when child is aged 8-9 = give us best chance of 7 moving into that space - upper arch = timing less critical, space closure likely if extracted before 11/12 yrs

Question 29

what is a compensating extraction?

Answer 29

-when we need to extract a lower 6 - upper 6 will over erupt - even if upper 6 has a good prognosis we would still extract that tooth THIS DOESNT WORK THE OTHER WAY ROUND (as lower 6's don't overerupt)

Question 30

what happens if we decide that these teeth can be restored or maintained?

Answer 30

Question 31

when do we use tooth mouse and what are the benefits?

Answer 31

1. use for sensitivity 2. used at home 3. pleasant for children

Question 32

when do we use fissure sealant ?

Answer 32

- if we feel enamel is nicely intact and we don't see caries in BWs - no sensitivity

Question 33

when do we use plastic fillings ? how do we do it ?

Answer 33

- when we need to restore - remove caries - remove defective enamel (obvs not the dentine) - therefore we get shallow cavities and need to be particular when choosing restorative material

Question 34

why would we not use amalgam?

Answer 34

Question 35

when do we use GIC?

Answer 35

- temp measure

Question 36

what is the best restorative material for MIH?

Answer 36

composite

Question 37

indications and contraindiactions for composite ?

Answer 37

Question 38

when do we use stainless steel crowns ?

Answer 38

- good at addressing sensitivity - very extensive defects

Question 39

what are the disadvantages of stainless steel crowns ?

Answer 39

(gingival quality is poor due to poorly adapted margins of MIH)

Question 40

what are the different ways in which we can restore incisors ?

Answer 40

- micro abrasion - bleaching - resin infiltration - COMPOSITE VENEERS (best) - porcelain veneers (contraindicated in children)

Question 41

pros and cons of microabrasion?

Answer 41

- only used for subsurface defects but we know MIH is full thickness of enamel or in the inner layer of enamel - very easy to do - easy for pt and parents - very conservative

Question 42

what is con of bleaching ?

Answer 42

- lightens whole tooth not just defects

Question 43

when do we use resin infiltrations ?

Answer 43

for white defects

Question 44

why is it better for child to grow and then get composite veneers?

Answer 44

- when tooth erupts fully you will see the margin of the veneer showing through