MIH Flashcards
Which cells form enamel?
ameloblasts
what is the stimulus that triggers ameloblasts to form enamel ?
dentine deposition
what happens when ameloblasts are triggered?
they secrete matrix proteins and then they become calcified to about 20% (initial calcification)
what function change do ameloblasts go through after the matrix proteins secretion phase?
they secrete enzymes which remove organic component and allows full mineralisation to 99% (maturation stage)
How does removing the organic content allow full mineralisation?
- the crystals are trying to expand and the organic component is takin gum loads if room and preventing the expansion (Maturation stage) = 99% mineralisation
which three stages do we see problems occurring ?
- secretion of matrix proteins
- calcification stage
- maturation stage
what happens when you have a disruption during the laying down of the enamel matrix
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
what happens if the problem occurs in early initial calcification stage or maturation stage?
HYPO MINERALISATION due to…
- disturbance of enamel formation therefore reduced mineral content
- less mineral in enamel therefore less calcification
- AKA hypocalcifiaction or hypo maturation
how can enamel defects be classified?
systemic or local
List the different ways in which we can get local enamel defects.
- trauma
- infection
list the different ways which we can get systemic enamel defects.
- environmental
- genetic = amelogenic imperfecta
what can environmental defects be further classified into?
- CHRONOLOGICAL = this defect has occurred at a very specific point in time as that enamel forms therefore specific teeth are affected. eg. MIH
- GENERALISED = the insult has been there for a longer amount of time eg. fluorosis
how can we describe enamel defects? (3)
- DEMARCATED = distinct, clear boundary, yellow, white or brown
- DIFFUSE = no clear boundary; lines patches
- HYPOPLASTIC = loss of enamel, pits and grooves
Give an eg of demarcated defects?
MIH
give an eg of diffuse defects?
fluorosis
Give eg of hypoplastic defects?
localised legions
give an eg of a condition which have all 3 defects ?
ameleogensis imperfecta
define MIH?
hypo mineralisation of systemic origin of one or more first permanent molars as well as affected incisors