Molar Incisor Hypomineralisation Flashcards
What is enamel hypoplasia?
A quantitative deficiency of developmental defects of enamel, which usually arise from disruptions of matrix formation
How does enamel hypoplasia manifest?
it may be expressed as:
Pits
Grooves
Thin enamel
Missing enamel
How is enamel hypomineralisation different to enamel hypoplasia?
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.
How does hypomineralisation distribute itself?
May be diffuse or demarcated, and coloured white, yellow, or brown.
What is molar incisor hypomineralisation? Which teeth are affected?
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
What is the worldwide prevalence of molar incisal hypoplasia?
Worldwide: 2.4 - 40.2%?
Australia: 22 - 44%
NZ: 14.9 - 18.8%
What are the pre-natal events that lead to molar incisal hypomineralisation?
Pre-Natal events:
Mother hypertension
Drugs during delivery
Assisted delivery / emergency caesarian
What are the peri-natal events that lead to molar incisal hypomineralisation?
Peri-natal events:
Foetal distress
Oxygen deprivation
Low birth weight / high birth weight / premature birth
What are the post natal factors that lead to MIH?
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
How does MIH present?
Demarcated enamel defects can be seen as an abnormality in the translucency of enamel.
Lots of variability in severity.
How can severity of MIH be assessed?
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.
How is the colour of a lesion related to the protein and mineral content?
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.
Which proteins are found in MIH lesions?
Albumin
Alpha-1-antitrypsin and antithrombin III
How is MIH diagnosed?
History
Clinical examination of teeth
Radiographic examination
Associated medical conditions
What problems can arise when trying to manage MIH?
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
What are the cross-sectional features of an MIH-affected first permanent molar?
Hypomineralised enamel
Transition zone
Unaffected enamel.
Characterized by many indents present along the structure of the tooth.
How can MIH be prevented?
Appropriate dietary advice
Use of fluoride: Fluoride tooth paste, fluoride varnish and fluoride mouthwashes.
CPP-ACP
Sugar free gums
Fissure sealants
Recall appointments
How can sensitivity caused by MIH be managed?
Plaque removal
Use of fluoride
CPP-ACP
Desensitizign tooth paste
Sealing with resin
Sealing with GIC
Resin infiltration
Compomers
How can MIH lesions be restored?
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
What factors are used to decide whether to extract a tooth affected by MIH?
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)
What are the 3 main options of managing extractions?
Immediate extraction: Infective, severely broken down
Delay extraction to optimize eruption of surroudning teeth (7s to move into place)
Extract as part of orthodontics
What are the contraindications for extraction?
Class II malocclusion
Deep bite
Lip trap
Brachyfacial type
Spacing
How should permanent anterior teeth be managed if they have MIH?
Micro-abrasion (with or without bleaching)
PMMA resin
Composite veneers
Zirconia veneers/crowns
When should first molars be extracted immediately, intermediate, or long term?
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.
What material should be used for long term restoration of teeth with MIH?
Immediate: Compomer, SSC, GIC
Intermediate: SSC, Composite
Long term: Gold/metal overlay, full crowns
