MIH Flashcards
What type of children are more likely to be affected by MIH?
Those with poor health during the first 3 years of life
Rules for balancing/compensating 6s
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
What causes hypoplasia
A disruption in the secretory phase. Occurs early in development forming gross enamel surface defects and small pits and grooves
What causes the increased sensitivity
- Greater innervation in the subodontoblastic/pulp horn regions
- Increased immune cell density
- Increased vascularity in sensitive teeth
- porous enamel – exposed dentine
- Activation of A delta fibres
- Underlying increase in c-fibre action
Aetiology of MIH
- Hypoxia of the mother/child
- Exposure to chemicals
- Peri-natal and neo-natal problems
- Common childhood illnesses and medically compromised children
What occurs in the secretory phase?
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
Advantages of using SSCs for MIH
- Single visit for placement
- relatively quick and simple procedure
- usually reduce sensitivity totally because the whole tooth is covered
- Inexpensive compared with cast restorations
- good retention rate
When do you not want to XLA the 6s?
when there is spaced dentition
with a severe class 2/3
in hypodontia
What does MIH stand for
Molar/ incisor hypomineralisation
General management of MIH
- Recognisation and review
- Desensitisation
- Temporisation
- Restore
- Extract
- Orthodontic integration
Restoring centrals with MIH
- Microabrasion
- Etch-bleach-seal
- Bleach
- Composite
- Bleach and composite
Prevalence of MIH
3.6 - 25%
What is MIH
Clinically hypomineralisation of systemic origin affecting one or more of the first permanent molars and any associated and affected incisors CHRONOLOGICAL DEFECT
Differential diagnosis of MIH
- Fluorosis
- Amelogenesis imperfecta
- Turner tooth
- Idiopathic hypomineralisation
How does CPP-ACP work
Casein phosphopeptide - amorphous calcium phosphate. Milk derived product that remineralises teeth. It provides bioavailable calcium, phosphate and fluoride ions to the tooth
Why does amalgam have limited use in MIH
It is non adhesive and therefore further post eruptive breakdown can jeprordise the filling
Managing sensitivity associated with MIH
- Repeated application of 5% sodium fluoride varnish. DURAPHAT
- Sensitive toothpastes
- Daily use of 0.4% stannos fluoride gels
- GIC/ Comp restorations
- SSC
How effective is LA when restoring a molar with MIH
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
When is the best time to extract the 6s
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
What are the two phases of Amelogenesis
Secretory phase and maturation phase
How does MIH present
- Demarcated patches
- White-brown, cream
- Post eruptive breakdown
- Missing 6s
- Heavily restored, abnormal restorations
- calculus
What causes hypomineralisation
Disruption in the maturation phase. Poor mineralisation of the matrix. Occurs later in development. There is the normal thickness of enamel but dubious quality
When do central incisors start to form?
3-4 months in-utero
Is it worse to extracts 6s too early or too late?
Too late. 5s are less likely to tip distally compared to 7s tipping mesially. It is difficult to close space involving a 7
Prevention of sensitivity and caries in MIH
Fluoride, desensitising toothpaste, CPP-ACP, fissure sealants and oral hygiene
What does the asymmetrical distribution of MIH suggest?
That ameloblasts are affected at a very specific stage in the development
Alternative terms for MIH
- Cheese molars
- Hypomineralised 6s
- Idiopathic hypomineralisation
- Non-fluoride hypomineralisation
Molar restoration
Compostie, SSC, Gold/CoCr onlays
What occurs in the maturation phase?
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.
Challenges faced by MIH
Patient and restorative factors.
What happens if you XLA the 6s too late or too early
too early - 5 tips too late - 7 tips
When do first permanent molars start to form and when do they calcify?
For after 4 months in-utero and calcify at birth
Microscopically what do you see in MIH
- Altered calcium/phosphate ratio
- Less distinct enamel rods
- Bacterial penetration of enamel
- Lower hardness of enamel
