Why crowding is the most common case
Causes include genetic tooth-size/jaw-size mismatch, late mandibular growth, wisdom teeth pressure, post-orthodontic relapse, periodontal changes, and tooth loss. Our guide to crowded teeth explains each cause in more detail.
The DWL approach — arch expansion over extraction where possible
We favour widening the arch within physiological limits over removing healthy teeth, because non-extraction preserves teeth, respects facial proportions, and supports better airway function. Our Invisalign treatment in Islington begins with a free consultation and iTero scan.
Crowding severity and tier matching
Mild (1-3mm): Express or Inman Aligners. Moderate (3-5mm): Moderate. Significant (5-8mm) and severe (8mm+): Unlimited, sometimes with selective tooth removal. Current Invisalign prices are listed on our cost page.
Retention for crowding cases
Crowding has the highest relapse risk of orthodontic conditions because underlying causes (genetics, late growth) often continue — a bonded wire retainer is often recommended. See also what retention involves after Invisalign.
Where extraction is genuinely needed, we recommend it. Where arch expansion can deliver, we prefer it.
By Dr Vishal Patel, BDS, MSc Aesthetic & Restorative Dentistry, GDC 103127, Invisalign Diamond II Provider. Last reviewed 2026-05-17.
