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Orthodontic Tx (Fixed Appliances (Aspects contd. + adv/ disadv (Movements:…

- - - - = Aims to correct dento-alveolar crossbite
        
        less side effects, more stable/physiological
        
        ex. Quad-Helix
    - - = aim to correct a skeletal posterior posterior crossbite
        
        The appearance of a temporary upper midline diastema (will close spontaneously)
        ex. Hyrex screw
      - Surgically Assisted Mx Expansion
  - - - Crown & Loop
        
        Variation of band & loop w/ SSC
      - Band & Loop
        
        simple well, fabricated,
        
        but plaque retentive, only single span
      - Distal Shoe
        
        Used to guide the eruption of 6s, band around the 1st primary molar and distal extended into the mesial of the 6
    - - Lingual Holding Arch
        
        bilateral loss or Mdb primary loss
      - Trans-Platal Arch (TPA)
        
        when bilateral Mx primary molars lost
      - Nance Button
        
        when Mx primary molars lost prematurely
        
        more stable than TPA
        
        Execpt arcylic button may cause irritation
- - - - From mesial 6 to 6
        
        segmented or wire
    - - Mesiodistal width of each pernament tooth
    - - If: space required > space available = CROWDING
        If: space required < space available = SPACING
  - - - From mesial 6 to 6
        
        segmented or wire
        = arch perimeter and leeway space
    - - Mesiodistal width of erupted permanent incisors
        
        Tanaka & Johnson
        
        Rx method
        
        Moyers
        
        Tanaka & Johnson
        1/2 of Mesio-Distal width of four lower incisors + 10.5 = Estimated width of mandibular premolars + canine in one quadrant
        1/2 of Mesio-Distal width of four lower incisors + 11.0 = Estimated width of maxillary premolars + canine in one quadrant
        
        Rx Method
        Individual PAs
        
        Moyers
        Estimation Tables
        = Mesio-distal width of lower incisors predict the size of mx & mand 3, 4, 5s
    - - If: space required > space available = CROWDING
        If: space required < space available = SPACING
  - - - Mild Crowding (<4mm)
        
        (mixed dentition) Spontaneous correction possible 7-9 years of age in association with normal growth.
        Exo of deciduous canines should be avoided, unless ectopic 3s
        
        (permanent dentition) This amount of crowding is often acceptable. If undergoing ortho tx – usually non extraction
      - Moderate Crowding (4-8mm)
        
        (mixed dentition) Space maintainers used to leeway space
        
        (permanent dentition) If remaining, can be tx non-extraction with fixed appliances
      - Severe Crowding (>8mm)
        
        Rotations and tipping frequent
        
        (permanent) Extractions often required
        – often best to wait until early permanent dentition arise
        --> NEEDS GOOD SPACE ANALYSIS
  - - - Leeway Space
        The sum of the primary tooth widths is greater than that of their permanent successors
        
        Maxilla – 0.9mm - 1.5mm per side
        
        Mandible – 1.7mm - 2.5mm per side
    - - Upper 6s can be distalised using a fixed oral appliance or extra-oral traction
        
        best done before eruption of the 7s
    - - Lateral expansion
        – allow 0.5mm space within the arch for each mm that the posterior arch width is expanded
    - - enlarge peg lateral
        
        reduced enlarged teeth
        
        interproximal stripping
- - - - Retraction of 3s
      - Molar Distalization
      - Arch Expansion (transverse)
        
        midline expander w/ hyrex screw and posterior capping
      - Biteplanes
        
        Anterior
        
        Posterior
    - - Twin Blocks
        
        A twin block is an orthodontic appliance. whose purpose is to lengthen the lower jaw by posturing it forward
      - Activators
        
        loose fitting acrylic block that redirect forces that improves the tooth arrangements and occlusal relations
    - - Hawley Retainer
      - Wrap-Around Begg Retainer
      - Essix/VFR
  - - - Labial Bow
        = Passive retention (potential for actively retract incisors)
      - Adams Clasp
      - Ball Clasps
      - C-Clasps
      - Southend Clasps
  - - - Z-springs
        Correct a lateral incisor that’s in Xbite
      - T-springs
        Correct canines and premolars in Xbite
      - Buccal retractors
        
        Brings a Canine back
    - - Hyrex Screws
        Expanders transverse
      - Expanders A-P
- - - - Anchorage
        How to limit the movement of teeth that do not need to move (force produces an equal and opposite reaction)
      - Retention
        To prevent relapse back towards the original malocclusion, patients need to understand this critical step
- - - - No retention
        
        Corrected anterior Xbites with adequate OB
        
        Corrected posterior Xbites with interdigidation, adequate buccal OB and minimal tipping
        
        Cases relying on spontaneous alignment following extractions
      - Permanent/Semi
        
        Expansion cases – REM, SME
        
        Spaced cases
        
        Multiple or severely rotated cases
        
        Periodontal cases
    - - Bonded:
        
        SS archwire
      - Removable:
        
        Hawley
        
        Essix/VFR