Fixed appliances are appliances attached to teeth and capable of a greater range of tooth movements than with removable appliances.
Through fixed appliances orthodontists can directly control the forces applied to the crown and root in 3 planes of space. Thus allowing the tooth to be moved bodily, tipped at the crown or root, and the tooth may also be intruded or extruded.

Components of fixed appliancesIndications for fixed appliancesContraindications for fixed appliancesRisks of fixed appliance therapyOrthodontic tooth movementOptimal orthodontic force rangesReferences
  • Attachments 
  • Brackets: bonded to the teeth by acid etch/composite or alternative systems 
  • Bonded molar tubes 
  • Bands: These are most commonly used on molar teeth due to aesthetic reasons but can be used on other teeth as well. 
  • Archwires: These are attached to the brackets along with auxiliaries, to provide tooth movement. The amount and type of force applied to an individual tooth can be controlled by varying the cross sectional diameter and form of the archwire and/or the material it is made of. These may be round or rectangular. The round wire is used initially, and the rectangular wire is used later in treatment. The closer the fit of the rectangular arch wires in a rectangular slot on the bracket the greater the control of the teeth. Despite there being various alloys, stainless steel is the most popular because it is: 
    • Relatively inexpensive 
    • Exhibits good stiffness 
    • Easily formed 
  • Auxillaries: 
    • Elastomeric modules 
    • Wire ligatures
  • Bodily movement of teeth  
  • Correction of rotation 
  • Closure of spaces 
  • Multiple movements required in either one or both arches 
  • Alignment of grossly misplaced teeth 
  • Overbite reduction by incisor intrusion 
  • Correction of mild-moderate skeletal discrepancies 
  • When precise tooth movements are required 
  • Intrusion/Extrusion of teeth
  • Poor oral hygiene 
  • Active caries 
  • Poor motivation 
  • Mild malocclusion
  • Caries 
  • Decalcification 
  • Gingivitis 
  • Loss of periodontal support 
  • Loss of bone support 
  • Root resorption 
  • TMJ dysfunction 
  • Failed treatment 
  • Pulp death 
  • Soft tissue trauma
  • Pressure and tension are placed on periodontal ligament in order to bring about tooth movement 
  • Tension causes the periodontal ligament to stretch 
  • Pressure causes compression of the PDL, when compressed lightly, tooth movement occurs as a result of compressed blood supply leading to osteoclastic invasion within 2 days. 
  • If compressed heavily, the blood supply is cut off producing an area of sterile necrosis (hyalinisation), incapable of osteoclastic differentiation, therefore tooth movement does not occur.
  • Tipping: 35-60g 
  • Bodily movement: 70-120g 
  • For rotation or extrusion: 35-60g 
  • For intrusion: 10-20g
  1. Littlewood, S.J. and Mitchell, L., 2019. An introduction to orthodontics. Oxford university press.
  2. Singh, G. ed., 2015. Textbook of orthodontics. JP Medical Ltd.
  3. Scott, P., Fleming, P. and DiBiase, A., 2007. An update in adult orthodontics. Dental update, 34(7), pp.427-438.
  4. Dowsing, P., Murray, A. and Sandler, J., 2015. Emergencies in orthodontics part 1: management of general orthodontic problems as well as common problems with fixed appliances. Dental update, 42(2), pp.131-140.

See also Functional Appliances