Learn Orthodontics

Fitting of Functional Appliances

Equipment Required

  1. URA adjust kit (Adams pliers, Round-flat pliers, Mauns cutters)
  2. rem instruments
  3. Straight handpiece , acrylic cutting bur (preferably tungsten carbide).


  1. Check
    • That the appliance is for the patient.
    • The design is the one requested.
    • The appliance fits the working model
    • The appliance has no sharp or rough surfaces, edges etc.
  2. Fit the appliance to the patient and check
    • It fits properly
    • The base plate fits closely
    • The retention (Adams clasps) fit correctly
    • It is not producing any discomfort

    If the appliance is a Twin Block - fit each part separately first to check fit and undertake any adjustment before fitting both components

  3. IF required, adjust the acrylic using the straight handpiece and acrylic bur
  4. Check the activation, i.e. overjet, when patient has closed into appliance.
    • Ensure that the appliance has not opened the patient too much
    • For a MOA (Medium Opening Activator) the opening between the premolars should be about 4-6mm
    • For a Twin Block the opening between the premolars should be about 3-5mm
    • If it is excessive seek advice from staff on adjustment
  5. Adjust the Adams clasps to ensure good retention


    On first visit do not get patient to use expansion screw - they have enough to get used to already. Start expansion after the first visit.

  6. Instruct patient and parents on appliance removal, insertion and care.
    • Functional Appliances are worn FULL TIME, removed only for cleaning (except for MOA's which need to be removed for eating)
    • Record the patient's overjet in ICP
    • Give patient a set of written instructions
    • Make next appointment for 4-6 weeks