#DEN4001
#D4/S1/W5
#Paediatrics

Molar Incisor Hypo mineralisation MIH

MIH

• development defects in the enamel of permanent molars and incisors
• type of enamel hypomin, quantitative deficiency of enamel mineralisation
• primarily affects first permanent molars, but also incisors
• demarcated creamy white to yellow brown opacities or discolorations on enamel surface
• 
• lower mineral content -> more prone to caries and fractures
• more sensitive to temperature changes/sensitivity
• developmental defect occur during mineralisation stages of tooth development, usually happens within first few years of a childs life
  • combination of genetic and environmental factors
  • prenatal and perinatal complications, childhood illnesses
  • exposure to certain environmental toxins may play a role
  • asthma, adenoid infections, tonsillitis, fever, antibiotics
• treatment involves addressing specific needs of the anemel
  • fluoride, selanat
  • filling/crown
• more important to receive regular dental care and to address complications

Diagnostic criteria

• demarcated opacity
  • normal thickness but white, yellow brown, still smooth surface
• post eruptive enamel browndown
  • deficiency of surface after eruption
• atypical restoration
  • resto extended to buccal or palatal smooth surface,
  • opacity at border of restoration
• extracted molar due to MIH
  
  
  
  

Prevalence

• about 20%
• similarly, there is hypomineralised second primary molars HSPM
  • increased likelihood for both if one

Management

teeth are

• increased porosity
• decreased hardness
• decreased mineral content
• defective microstructure
• increased carbonate content
• poor bonding properties
• associated pulpal changes

results in

• extreme sensitivity
• ineffective LA
• increased caries risk
• wear
• erosion
• post eruptive breakdown
• poor restorative results

Six steps to managing

• risk identification
• early diagnosis
• remineralisation and desensitisation
• prevention of dental caries and posteruptive enamel breakdown
• restorations and extractions
• maintenance

Factors to consider/Management for anterior teeth

• 
• management
• microabrasion
  • either 18% HCl or 37% phosphoric acid followed by CPP ACP remin agent
• composite restorations
• resin infiltration
  • ideally with triethylene glycol dimethacrylate monomer (TEGDMA)
  • need better OH practices as infiltrated enamel is more susceptible to staining
• porcelain veneer / crowns
  • wait until late adolescene when teeth are fully erupt and gingival architecture stable
• etch bleach seal
  • questionable effectiveness
• external bleaching
  • strongly consider side effects of gingival irritation and sensitivity

Management of first permanent molar

• difficult when tooth is restorable but questionable prognosis
• considerations for tooth preparation
  • all defective enamel removed to sound surfaces, best when adhesive material for enamel bonding
  • remove only very porous enamel, more conservative but defective enamel can continue to break down, use slow speed to determine enamel quality
  • hypo mineralised enamel should be left if no sign of clinical breakdown after 3-4 years
  • hypomineralised enamel contains more protein than normal, can be treated with sodium hypochlorite to remove
• restorative materials
  • amalgam, best to avoid
  • GIC, poor wear resistance and best for temp only
  • composite resins, small class I or 2 surface not involving cusps, where teeth are not sensitive
  • gingival 1/3 of hypomin teeth are usually normal enamel, bonding in this region produces stable results
  • SSC
  • lab made crowns
• for considering extractions
  • immediate management of dental pain
  • long term prognosis of restored tooth
    • large resto
    • pulpal symptoms
    • severe hypomin
  • dental age
  • type of malocclusion
  • presence and condition of other permanent teeth
  • balancing and compensating extractions
  • timing
    • best to exo first permanent molars between 8.5 and 10.5 years old, usually coincides with commencement of calcification of bifurcation of second molars
    • timing more critical in mandible, if wanting space closure, early exo is better than later
    • if first molar exo is done before 8yo, may result in 2nd premolar distal drift and rotation
    • extractions undertaken after 12 years may result in spacing, tilting, rotation of teeth
    • relationship between 2nd premolar and 2nd deciduous molar is very crucial, might need to exo 2nd deciduous molar same time as 1st molar to encourage vertical eruption of premolar
    • 
    • 1st mandibular molars exo and ideal mesial drift of 2nd and 3rd molars

Balancing and compensating

• amount of overjet and crowding (buccal and labial) influence decisions around balancing and compensating extractions
• verify radiographically that other permanent teeth are present and in correct positions
• if 2nd premolar is tipped and only resorbing distal rot of 2nd deciduous molar, consider exo after 2nd premolar has half of its root formation
• if 2nd premolar excessive meso angular inclination, more likely to tip mesially ands require ortho uprighting
• should be no radiographic evidence of hypoplasia of unerupted premoalrs or 7s
• if premolar is missing, restoration of 6s is preferred
• if 7s are absent, 8s are very likely to be absent so really need to preserve the 6
• CASES
  • balancing exo = contralateral side same arch
  • compensating exo = ipsilateral side opposite arch (antagonistic)

Consequences of loss of 6s

• mandibular
  • mesial tilting and lingual rolling of 7s, occlusal forces encourage mesial tilt and the lingual plate is thinner, can result in scissor bite
  • over eruption of 6s if no occlusal stops, occlusal interference may prevent lower 7 to drift mesially, and predispose to TMD, compensating exo for upper 6 should be considered if not replacing lower 6
  • incomplete space closure or formation of poor mesial contact if minimal arch crowding
  • minimal space closure if broad and well spaced arch
  • distal drift and tilt of the 5
  • atrophy of alveolar bone if space closure incomplete
• maxillary
  • maxillary molars develop with distal angulation, which favours spontaneous space closure, good approximation between 7 and 5 if 6 is exo around eruption of 7
  • if class I buccal segment relationship, mandibular 6 will rarely over erupt as M cusp will occlude with maxillary E or 5
  • if class II buccal segment relationship, mandibular 6 may over erupt, consider compensating exo of mandibular 6, only if favourable conditions for space closure in mandible, dental age 8-9, crowding present
  • avoid maxillary 6 exo in CIII malocclusion