Hypoplastic and Hypomineralised Teeth

• Hypomineralisation = qualitative defect - normal amount of enamel but poorly mineralised
• Hypoplasia = quantitative defect - insufficient amount of enamel and occasionally poorly mineralised

  • Left central incisor is yellowish and poorly mineralised
  • RHS picture = hypoplastic tooth with good mineralisation

  
• Molar-Incisor-Hypomineralisation (MIH) = qualitative defect of 1-4 first permanent molars with or without the maxillary and mandibular permanent incisors.

  • Permanent molars here showing varying degrees of hypomineralisation - they're not hypoplastic
  • There's also hypomineralisation of the second primary molar - link between these teeth; similar calcification dates
  • Brown areas have higher protein content; it will affect how we can help to manage these teeth

  
• Post-eruptive breakdown:

  • Loss of enamel of a tooth, after tooth eruption, that has hypomineralisation and/or hypoplasia
  • Attrition, erosion and caries can accelerate an already compromised surface
  • Picture = loss of tooth tissue on palatal cusp

  
• Post-eruptive breakdown:

  • Can only confirm post-eruptive breakdown with radiographs
  • First permanent molar looks intact with normal enamel on upper and lower (LHS)
  • Then 2 years later (RHS) you can see rapid destruction with loss of structure - enamel shearing off

  
• Hypoplasia due to renal transplant (at 2 years old):

  • Hypoplastic effects caused during the development of the teeth - not due to eruption

  
• Alternatives to hypomineralisation/hypoplasia:

  • All teeth affected in a symmetrical pattern - not seen in hypomineralisation/hypoplasia

  
• Clinical presentation/distribution of molar-incisor-hypomineralisation (MIH):

  • The more molars affected, the:
  • Increased overall defect severity
  • Increased probability of having affected incisors (since permanent molars come through before incisors)
• Aetiology of molar-incisor-hypomineralisation (MIH) - genetics:

  • Genetic influence - greater concordance rates of MIH in identical vs non-identical twins
  • Environmental influences - household income & gestational haemorrhage
  • Therefore, "epigenetic" gene-environmental interaction
  • Epigenetics = where the proteins which code the DNA are actually changed and altered because of environmental influences
  • It's this change in the protein of the DNA structure which leads to disruption in the amelogenesis pathway

  
• Aetiology of molar-incisor-hypomineralisation (MIH):

  • Childhood illnesses often have various associated features: hypoxia, hypocalcaemia, fever, malnutrition
  • Associated features causes the disruption to amelogenesis
  • It is a common misconception that MIH is caused by antibiotic use
  • Antibiotics are often prescribed for recurrent infections/childhood illnesses

  
• Pathophysiology of molar-incisor-hypomineralisation (MIH):

  • Ameloblasts  are sensitive cells
  • Impaired function during maturation phase of amelogenesis
  • The length and severity of disruption in ameloblastic activity will affect the macroscopic appearance of the enamel
  • Normal enamel rods tend to be straight and uniform in shape, size and mineralisation
  • MIH enamel rods are often different shapes and have different levels of mineralisation
  • Repetitive occlusal forces, over time, can lead to post-eruptive breakdown

  
• Pathophysiology of molar-incisor-hypomineralisation (MIH):

  • Because of the lack of mineralisation, lack of shape and lack of uniformity - the stress can't be spread out over all the uniform rods, and thus undergo post-eruptive breakdown

  
• Pathophysiology of molar-incisor-hypomineralisation (MIH):

  • Increased susceptibility of caries due to the structural defect and subsequent post eruptive breakdown
  • More places for bacteria to get trapped

  
• Histopathology of molar-incisor-hypomineralisation (MIH):

  • Hypomineralisation in MIH begins at the amelodentinal junction (ADJ) and not at the surface of the enamel:
  • Mild MIH = limited to the inner enamel while the outer surface is intact
  • Severe MIH = whole enamel layer is hypomineralised
• Problems in molar-incisor-hypomineralisation (MIH):

  • Pain and discomfort
  • Avoidance of smiling/social occasions
  • Drinking cold drinks
  • Food impaction, halitosis
  • School attendance
  • Sleeping
  • Chronic low-grade sub-clinical pulpal inflammation:
  • Increased sensitivity
  • Difficult to anaesthetise
  • Difficult to brush
  • Poor aesthetics
  • Pt expectations (be realistic)
  • Parents - may respond differently to child - therefore important to ask child their feelings
  • Impact self-esteem and quality of life - avoidance of smiling
• Treatment philosophies for molar-incisor-hypomineralisation (MIH):

  • Early coverage of molars to:
  • Reduce sensitivity
  • Prevent caries
  • Minimise future structural tissue loss
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Preventive counselling
  • Desensitising
  • SDF
  • Fissure sealants
  • Glass Ionomer Cements
  • Direct restorations
  • PFMC
  • Indirect restoration
  • Endodontic considerations
  • Orthodontic considerations
  • Extractions
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Desensitising
  • Toothpastes
  • Tooth Mousse - a topical application which allows a pool of calcium and phosphate to help saturate and improve the mineralisation of teeth by buffering plaque acid - also helps with sensitivity
  • Duraphat varnish
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Silver diamine fluoride
  • Very early use in MIH has been suggested
  • Doesn't restore structure; reduces carious activity
  • Black colour = silver putting a crust over teeth to stop any further carious activity
  • Won't help with sensitivity either

  
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Fissure sealants
  • Resin-based
  • Washing and drying could be challenging
  • Consider extending etch time
  • Bonding recommended - to improve retention rates
  • Glass Ionomer Cement:
  • Alternative to conventional fissure sealant if increased sensitivity
  • Poor wear resistance
  • Temporisation until optimal time for extraction

  
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Restore or extract
  • Extract indications:
  • Symptomatic
  • Severely affected
  • Orthodontic considerations
  • Lack of cooperation (possible need for GA)
  • Restore indications:
  • Mildly/moderately affected
  • Good cooperation
  • Hypodontia
  • Advances in bonding
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Restore - direct restorations:
  • Amalgam - not permitted in children
  • Glass Ionomer Cement - not a definitive restoration
  • Composite good success
  • Margins on sound enamel
  • Rubber dam isolation
  • Expect failure
  • Regular monitoring
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Restore - preformed metal crowns:
  • Treatment of choice for severely affected teeth
  • Act as a temporary (until extraction) or/until mature to have cast restoration
  • Age/cooperation consideration
  • For Hall technique, separator placed first, then PFMC
  • Otherwise, conventional prep (minimal occlusal and interproximal reduction - local anaesthetic)

  
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Restore - indirect restorations:
  • Minimal tooth restoration
  • Ideal; in young permanent molars we tend to have large pulps and don't want to expose them
  • Sound enamel margins
  • Inlay, onlay, 3/4 crown or full coverage
  • Cuspal coverage
  • Bond under rubber dam - to improve retention
  • Material options
  • Nickel-Chrome
  • Gold (ideal, but very expensive)
  • Indirect composite
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Extraction - considerations
  • Optimal spontaneous space closure - extract at 8.5-10.0 years
  • Orthodontic considerations
  • Compensation related to incisal relationship
  • Buccal segment crowding
  • Dental development

  
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Extraction - ideal time; got all required factors
  • 8s present with bifurcations - mesio-angulated
  • 5s are in the furcation, not distoangulated but that's fine
  • Upper 7s have almost fully closed, lowers getting there

  
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Extraction
  • Compensating - extraction of the same tooth in the opposite arch
  • Prevents over-eruption
  • Balancing - extraction of the same contralateral tooth (eg UL5 and UR5)
  • Prevents centre-line shift
  • In general:
  • Extract a lower molar - compensate upper
  • Extract an upper molar - don't compensate lower; lower wouldn't cause overeruption
  • Never balance FPM (first permanent molar)
  • Risk of overeruption of upper FPM, & prevent 2nd permanent molar from mesially migrating
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Extract - compensating extractions
  • Class I incisors - extract lower at ideal time & usually compensate
  • Class II incisors - extract lower at ideal time - if crowding, delay extraction of upper until all teeth have erupted and utilise space
  • Class III incisors - refer to orthodontist for opinion
• Treatment options for molars in molar-incisor-hypomineralisation (MIH) - start off basic and move towards extraction:

  • Extract
  • Often the best option if severely affected, symptomatic or patient cooperation would prevent restoration
  • Orthodontic and developmental considerations are required to plan
  • Think carefully about compensating extractions
  • If in doubt, refer for a paediatric/orthodontic opinion before extracting
  • Timing more critical in the lower arch
• Treatment philosophies for molar-incisor-hypomineralisation (MIH):

  • Minimally invasive options for incisors to:
  • Reduce sensitivity
  • Improve aesthetics
  • Maintain as much tooth tissue as possible
• Treatment options for incisors in molar-incisor-hypomineralisation (MIH) - again, go from least invasive to most invasive:

  • Tooth mousse
  • Bleaching
  • Resin infiltration
  • Pumice acid microabrasion
  • Composite making
  • Composite restorations
  • Composite veneers
• Treatment options for incisors in molar-incisor-hypomineralisation (MIH) - again, go from least invasive to most invasive:

  • Vital bleaching
  • The GDC have left the decision for the clinician to make - act in your patients' best interest whilst obeying the law
  • Set realistic expectations
  • Not for "Hollywood smile"
  • Pre-op discussion
  • Worse initially
  • Masking only
  • Sensitivity
  • Staining
  • Relapse
  • Pre-op essentials: consent, clinical photographs with shade guide pre- and post-op
• Treatment options for incisors in molar-incisor-hypomineralisation (MIH) - again, go from least invasive to most invasive:

  • Resin infiltration
  • Infiltration fills the lesion and refracts the light in a similar manner to natural tooth tissue
  • Refractive index of:
  • Sound enamel is 1.62
  • Hypomineralised enamel when wet is 1.33
  • Hypomineralised enamel when dry is 1.0
  • ICON most commonly used
  • When the resin infiltrates the porous enamel, by capillary forces, the refractive index increases to 1.52, which is similar to sound enamel
• Treatment options for incisors in molar-incisor-hypomineralisation (MIH) - again, go from least invasive to most invasive:

  • Acid microabrasion
  • Removes between 100-200 microns of enamel to produce prism-free surface layer, altering the optical properties of the tooth
  • Brown opacities have been found to be more easily removed than white opacities
  • 18% hydrochloric or 37% phosphoric acid
  • Soft tissue damage, risk of over-abrasion
  • Similar pre-op as Vital Bleaching
• Treatment options for incisors in molar-incisor-hypomineralisation (MIH) - again, go from least invasive to most invasive:

  • Composite masking
  • No tooth preparation!
  • Opaque composite in base - or fissure sealant/panavia
  • Overlying translucent composite
  • Increased thickness of tooth
  • Bonding issues
  • Staining at margins and long term maintenance
• Treatment options for incisors in molar-incisor-hypomineralisation (MIH) - again, go from least invasive to most invasive:

  • Composite restoration
  • Critical that margins are "sound" enamel
  • Attempt to remove as little as possible!
  • Application of panavia/fissure sealant to mask if necessary
  • Staining at margins and long term maintenance

  
• Treatment options for incisors in molar-incisor-hypomineralisation (MIH) - again, go from least invasive to most invasive:

  • Composite veneers
  • LA
  • Rubber dam isolation
  • Clamp
  • Crown forms
• Molar-incisor-hypomineralisation (MIH) in the primary dentition:

  • Known link with MIH and Hypomineralised Secondary Primary Molars as similar calcification dates
  • 2nd Primary Molar Treatment Options
  • Prevention
  • Desensitisation
  • Fissure sealant
  • GIC
  • Localised composites
  • PFMC
  • Extraction