Molar Incisor Hypomineralisation Flashcards
(30 cards)
What is the definition of MIH
- Developmentally-derived dental defect
- Involves hypo mineralisation of 1 to 4 permanent first molars
- Frequently associated with similarly affected permanent incisors
Difference between hypo plastic and hypo mineralised
Hypoplastic
- Ameloblasts fail to produce appropriate thickness of enamel
- Enamel crystals do not grow to the appropriate length
Hypomineralised
- Defect in initial crystallite mineralisation
- Crystallites fail to grow in thickness and width
What 3 things do you look for to make a diagnosis of MIH and description of each
Permanent first molars and incisors
- One to all four FPM shows hypo mineralisation of enamel
- If more molars and incisors are affected, the more severe
Demarcated opacities
- Clear demarcated opacities at the occlusal and buccal parts of the crown
- Vary in colour and size
- White, creamy or yellow to brownish
- Negligible or comprise the major part of the crown
Enamel disintegration
- Degree of porosity of hypo mineralised areas varies
- Severely affected enamel subjected to masticatory forces soon breaks down, leading to unprotected dentine and rapid caries development
- Post eruptive enamel breakdown
What colour do you expect opacities
-White, creamy or yellow to brownish
What is the official way of classifying MIH in terms of severity
Mild:
- Demarcated opacities are located at non-stress bearing areas
- No caries associated with the affected enamel
- No hypersensitivity
- Incisor involvement is usually mild if present
Moderate
- Demarcated opacities present on both molars and incisors
- Post-eruptive enamel breakdown limited to less than 2 surfaces WITHOUT cusp involvement
- Atypical restorations can be needed and normal
Severe:
- Post eruptive enamel breakdown
- Crown destruction
- Caries associated with affected enamel
- History of dental sensitivity and aesthetic concerns
Aetiology of MIH
Unknown
3 stages of amelogenesis and what goes down in eachh
1) Secretory. Issues here can cause hypo plastic enamel which is pathologically thin
2) Transition and 3) Maturation
Issues here can cause hypo mineralisation and hypo maturation where enamel is pathologically soft
Ameloblasts during early stages of maturation are highly sensitive to environmental disturbances
Mineralisation guide
-Learn on slide 15
When is the most critical period for enamel defects of FPM and incisors and why
-First 2.5 years of life as these coincide with early maturation
What are some of the reasons that enamel defects could occur and classify them
Prenatal factors
- Maternal pyrexia
- Medication
- Prolonged vomiting
- Maternal diabetes
- Maternal illness
Perinatal factors
- Caesarean section
- Prolonged/complicated delivery
- Hypoxia
- Prematurity/low birth weight
- Hypocalcaemia
Post-natal factors
- ENT infections
- Respiratory problems
- Pyrexia
- Prolonged meds
- Antibiotics
- Breastfeeding
- Chickenpox/mumps/measles
Prevalence of MIH
14.5% of UL population
What makes clinical management difficult
- May present with PEB of affected enamel
- Atypical location- shallow broad lesion
- Teeth may be sensitive
- Poor OH and caries
- Hypersensitivity and difficulty in obtaining adequate local analgesia
- Think IHS
-Restorations often fail
What does the colour of the lesion tell you about severity
- Yellow or brownish defect are of full thickness and more porous
- White or creamy white are less porous and variable in depth
6 Management stages for MIH
6 step management approach by William et al.
1) Risk identification
2) Early diagnosis
- Prevents PEB, reduces sensitivity and minimises care burden
3) Remineralisation and desensitisation
4) Prevention of dental caries and PEB
5) Restorations or extractions
6) Maintenance
According to Delivering better oral health 2014, what advice should be given 7yo with MIH
Enhanced prevention
-As with normal prevention AND
- Fluroide mouth rinse daily (0.05% NaF) at a different time to brushing (8+)
- Fissure seal permanent molars with resin sealant
- Apply fluoride varnish to teeth two or more times a year (2.2%)
- If 10+, prescribe 2800 ppm fluoride toothpaste
- If 16+, prescribe either 2800 or 5000ppm
- Investigate diet and assist to adopt good dietary practice in line with the eat well plate
CPP-ACP
Also can be used
-Look up some info on this not much on slides
How can one restore a first permanent molar and what does the choice depend on
- RMGIC
- Composite resin
- ONC
- Cast inlays/crowns
Co-operation, severity, longevity of restoration, load bearing area, extent of PEB (cusp involvement) and orthodontic needs
How would the location of the tooth that needs to be restored affect your decision of material
- GIC, RMGIC not recommended in load bearing areas
- Only recommended material for one or more surface restorations in MIH molars in composite resin
Approaches to restoring a MIH tooth and +/-ves
1) Removal of all defective enamel until sound surfaces are reached
2) Removal of the porous enamel only, until resistance to the bur or to the probe is felt
- First approach means that a lot of tooth material is lost but is better if an adhesive material is to rely upon bonding to enamel
- Second is less invasive but it can mean the defective enamel may continue to chip away
What is the most commonly used restoration for FPMS with MIH
- PMCs
- Cover molars with defective enamel
- Recommended tx option
- Prevents further tooth loss, controls sensitivity, establishes correct IP and proper occlusal contact points
When do we extract MIH molars
- Assure that other molars are not affected
- Mild cases may be acceptable long term
- Assess occlusion for extraction of 6s- other teeth present, stage of 7s roots, class 1 occlusion, minimal crowding, 5’s inclination
If suitable,
- Decide the time of extraction
- Glass ionomer restorations to maintain with comfort
If unsuitable, consider type of long term restoration and timing
-Remember sensitivity
If doubtful prognosis for one or more first permanent molars in a patient with high caries incidence it is wise to consider the possibility of all 4 first molars extraction
What form of radiograph should be used
- If early mixed dentition, DPT
- If late mixed dentition and you are assessing a single tooth, bitewing
- If late mixed and you are assessing multiple teeth, DPT
DPT determines presence of successional teeth and development
Criteria for consideration of loss of first permanent molars
1) Underlying malocclusion
2) No missing teeth- including 8s
3) Timing- calcification of the bifurcation of 7s
4) Extent and location of crowding
5) Prognosis (long-term)
6) Which 1st permanent molars are affected
When is the correct time to remove FPM
-When bifurcation roots of the 7s just forming
