Molar-incisor hypomineralisation (MIH) Flashcards
What is MIH?
hypomineralisation of systemic origin of 1 or more of the 4 permanent first molars as well as any associated and affected incisors
What does MIH stand for?
Molar incisor hypomineralisation
What are the alternative names for MIH?
Cheesy molars, hypomineralised 6’s, idiopathic hypomineralisation, non-fluoride hypomineralisation
What is the prevalence of MIH?
3.6-25%
What are the possible differential diagnoses for MIH?
Fluorosis, amelogenesis imperfecta, turner tooth, idiopathic hpomineralisation
How can we differentiate between MIH and fluorosis?
Fluorosis is less common and effects all teeth
How can we differentiate between MIH and amelogenesis imperfecta?
Amelogenesis imperfecta often affects most teeth and runs in the family
How can we differentiate between MIH and a turner tooth?
A turner tooth affects only a localised region (often of a single tooth)
What is a turner tooth?
It is where a really decayed deciduous tooth affects the tooth germ of the permanent tooth
How does MIH present?
- affects 1+ molar and/or incisor
- demarcated patches
- white/brown/cream
- post-eruptive breakdown
- heavily restored, abnormal restorations
- calculus = sensitivity means avoid eating or brushing on the area
Which discolouration is easiest to remove?
Brown staining
What are the different causes of MIH?
Timing of insult, pyrexia, hypocalcaemia, hypoxia (child or mother)
What does critical review of the causes of MIH show?
- not really sure but likely factors include: exposure to chemicals, perinatal and neonatal problems, common childhood illnesses and medically compromised children
What is the evidence that a likely factor causing MIH is exposure to chemicals?
e.g. environmental contaminants = moderator evidence connected with breastfeeding, early cessation of breast feeding = more defects, fluoride = weak evidence (more diffuse effects)
What is the evidence the perinatal and neonatal problems cause MIH?
May increase prevalence: malnutrition, maternal health and birth problems, visible defects in e’s (coexisting factors), many confounding factors and weak evidence
What is the evidence that common childhood illnesses and medically compromised children cause MIH?
No clear evidence about cause, e.g. resp problems, otis media or other common illnesses, problems with parental recall and confounders, chronic medical problems e.g. coeliac, renal, cystic fibrosis
Which phase in development is disrupted in hypoplasia?
The SECRETORY phase (early in development)
How does hypoplasia present?
small pits and grooves, qualitative defect = gross enamel surface deficits (comes through good and breaks down quickly)
Which phase in development is disrupted in hypomineralisation?
The MATURATION phase (poor mineralisation of the matrix - later on in development)
How does hypomineralisation present?
White/brown opacities
= normal thickness but dubious quality enamel
What does hypomineralisation look like under a microscope?
Altered CaP ratio, less distinct mineral rods (harder for composites to bond to), bacterial penetration of enamel and lower hardness of enamel
What are the 2 main areas of challenge in treating MIH?
Patient factors = behaviour management, sensitivity and appearance; and restorative factors
Why may behaviour management be more of a challenge in MIH patients?
Young pt, repeated restorations (nothing sticks to an MIH, etching doesn’t make the keyhole pattern), LA, fear (told its just air but it hurts)
Why is sensitivity an issue in MIH patients?
Porous enamel = exposed dentine and movement of dentinal fluid, underlying increase of c fibres, activation of a delta fibres, increased immune cell density, increased vascularity and greater innervation in subodontoblastic/pulp horn regions
Why is appearance an issue in MIH patients?
Managing expectations is important, often at time transitioning to secondary school, both the parents and childrens
What are the different restorative factors?
Bonding (etching doesn’t work properly and difficult to dry properly -> sensitivity), site, caries development, LA not ver effective, colouration, overeruption of upper molars, immature dentine, crumbly nature of tissue
Which teeth affected by MIH break down less and are less sensitive?
Incisors
Why are deciduous teeth whiter?
They contain more organic material (n.b. permanent teeth = 95% mineralised by weight and
At what age does tooth formation start?
6 weeks in utero
When do 1st permanent molars start forming?
4 months in utero (start calcifying at birth)
When do central incisors and lower lateral permanent incisors start forming?
3-4 months in utero
When do the upper lateral permanent incisors start forming?
10-12 months
Which % of MIH patients had infections below the age of 3?
60-70%
Which common illnesses had a correlation with MIH?
Chickenpox and antibiotic use
What happens in amelogeneisis?
Odontoblasts secrete collagen type 1, ameloblasts differentiate, secrete enamel proteins, these change shape and cause mineralisation
What happens in the secretory phase of amelogenesis?
= defines the form of the tooth, deposition of organic matrix + small thin crystallites = incremental growth in thickness = not continuous process
What happens in the maturation phase of amelogenesis?
= establishes quality of tooth, degradation of the organic matrix = mineralisation (ameloblasts move Ca and PO = process continues post eruption = apoptosis of ameloblasts
What are the solutions we can use for MIH molars?
Surveillance, recognition & review, Prevention, Desensitisation, temporisation, orthodontic collaboration, restore or extract
What does surveillance include?
(13 week referral) = knowledge of prevalence (3.6-25%) - hypomine/hypoplasia of primary - past medical history - family history - review as teeth erupt
What does recognition and review include?
Consider differential diagnosis, review according to caries risk and presence/absence of problems, implement prevention
What does prevention include?
Fluoride desensitising toothpaste, CPP-ACP products, fissure sealant, oral hygiene
What does desensitisation include?
Duraphat varnish, hall crown, temporise with GIC
What does restoration include?
Composite, stainless steel crown, gold/cobalt chrome onlays
What are the benefits of stainless steel crowns for MIH?
Good longevity, easy to fit, separators can be used, occlusal dimension settles, but :( gingival health and the erupting 7’s can impact :(
What are the benefits of gold/cobalt chrome onlays?
Well tolerated, fantastic longevity, not much difference at 2 years vs stainless steel crowns, considered permanent but the lab bill :(
When is extraction considered?
Depends on the extent of damage, consider the structure of enamel, age, presence of adjacent teeth, occlusal/orthodontic factors
n.b. if tooth has poor prognosis, decision is age dependant (furcation of lower 7’s on dpt, if xla too early, 5 tips, if too late 7 tips)
What does orthodontic collaboration include?
extraction so 7 can erupt naturally into 6’s space and rules for balancing and compensating the 6’s
What are the rules for balancing/compensating Class I molars?
Compensate (balance if overcrowded)
What are the rules for balancing/compensating Class II molars with minimal crowding?
extract U6’s if likely to over erupt, if not maintain until 7’s erupt (no balancing)
What are the rules for balancing/compensating Class II molars with crowding?
Compensate if U6 likely to over erupt, remove before/after 7’s erupt (no balancing)
What are the rules for balancing/compensating Class III molars?
Orthodontic advice sought (avoid balancing and compensating)
What is balancing?
A balancing extraction is a tooth from the opposite side of the same arch, designed to minimise centreline shift.
What is compensating?
Compensation means extraction of a tooth from the opposing quadrant to the enforced extraction. It is designed to minimise occlusal interferance by allowing teeth to maintain occlusal relationships as they drift. It is more difficult to justify compensation than balance, especially when it would involve removal of a tooth from an intact arch.
What are the treatment solutions for MIH incisors?
Surveillance, recognition & review, consider pt. factors, repair/aesthetics
What does repair/aesthetics include?
Microabrasion (removes brown), etch-bleach-seal (60 second etc, bleach with 5% NaOCl 5-10 mins, re-etch and place clear fissure sealant), composite, bleach and composite
