Also known as “Palatal expansion”
Example: Orthopaedic maxillary or palatal expansion in an early teenager. A temporary diastema develops with successful expansion due to the mid-palatal suture separation.
Level of evidence: Moderate
Suitable for ages: 8 to 15 years old (the maxilla transverse stops growing shortly after the canines erupt and the ability to achieve orthopaedic expansion is minimal in the late teenage years with any appliance bonded to teeth only; TAD-based expanders have shown abilities to achieve orthopaedic expansion of patients above 20 years old however the available evidence is still currently weak to moderate)
Indications: Transversely constricted maxilla, narrow palate, bilateral and unilateral posterior crossbites
Contraindications: No transversely constricted maxilla relative to the mandible, well interdigitated maxillary sutures (mid to late teenagers and older), immature skeletal structures and nasal septum (too young patients can have any expansion distort their vomer and nasal profile), any orthodontic acquired risks.
Speed of expansion:
- Rapid expansion is 2 turns a day at approximately 0.5mm activation per day
- Semi-rapid expansion is 1 turn a day at approximately 0.25mm activation per day
- Slow expansion is 1 turn every 2 days at approximately 1mm expansion per week
The evidence has now showed no difference in net skeletal expansion amongst the different expansion rates, where older children can benefit from rapid expansion initially to open the sutures but can reduce to a semi-rapid or slow expansion thereafter and younger children can benefit purely from a semi-rapid or slow expansion regime (Geran et al. 2006, McNamara et al. 2003, Proffit et al. 2013).
Treatment Objectives and Biomechanics
- Orthopaedic expansion of maxilla
- Elimination of posterior crossbites
- Eliminate/manage/refer for causative factors (e.g. adenoiditis and tonsilitis)
Appliances / Treatment modalities
- Fixed appliances – Hybrid hyrax palatal expander (bonded or banded), Quad-helix, W-expanders, Fan expanders etc.
- Skeletal anchorage – TAD supported (MARPE or C-expander)
