Orthodontic Elastics (Rubber Bands) UK: Class II, Class III and Interarch Elastics

What do orthodontic elastics do?

Elastics add force between upper and lower teeth to correct bite relationships that braces alone cannot fix. Class II elastics commonly help reduce increased overjet, Class III elastics help underbite tendencies, and vertical or box elastics help settle open contacts.

Interarch elastics versus the small bands on each bracket

The coloured or clear ties that hold the archwire onto each bracket are ligature elastics, fitted by the orthodontist and changed at appointments. Interarch elastics are different: you fit them yourself, and they stretch between hooks or buttons on the upper and lower arches so that they pull the two arches in relation to each other. Your orthodontist prescribes exactly which hook connects to which, and the pattern may change as treatment progresses, so ask for a diagram or photo if you are unsure. Latex-free elastics are available and work in the same way if you have a latex allergy.

Class II and Class III elastics: what they can and cannot correct

Class II elastics usually run from an upper canine hook back to a lower molar and are used to reduce an increased overjet or deep overbite. Class III elastics run the opposite way, from a lower canine hook to an upper molar, to reduce an underbite tendency. Both work by moving teeth within the bone, not by changing jaw size. Where the discrepancy is mostly dental they can correct it well; where it is skeletal, elastics can only camouflage part of it, and growth modification or combined orthodontic and jaw surgery may be needed. Ask whether your case is dental, skeletal or both.

Vertical, triangle and box configurations

Vertical elastics run straight up and down between upper and lower brackets on the same side and help close an open bite. Triangle elastics use three attachment points to correct a front-to-back and vertical problem at once, and box elastics use four points to settle the bite in one region, often near the end of treatment. The configuration is chosen for your specific correction and may be changed at each visit, so never keep using an old pattern once you have been given a new one.

Elastic sizes and strength

Elastics come in different diameters and force levels, and packets are labelled with a code for the size and strength your orthodontist has prescribed. Light elastics are generally used for fine-tuning and heavier ones for larger bite corrections. Change them at least every 24 hours, because latex loses force as it is stretched and warmed in the mouth. Keep a note of the code on your packet, store spares somewhere cool and out of direct sunlight, and ask the practice for more before you run out rather than substituting a different size.

Common mistakes with orthodontic elastics

The most common errors are hooking onto the wrong brackets, wearing elastics on one side only, doubling up bands to make up for missed time, carrying on with an old configuration after it has been changed, and stopping early because the bite looks nearly finished. One-sided wear creates uneven forces that can make the bite worse, and stopping without being told to can undo weeks of progress in the final stages. If you are unsure about any part of your elastic instructions, ask at your next appointment or call the practice.

How long should elastics be worn each day?

Elastic wear is prescribed individually rather than set by a general rule, so follow the schedule your orthodontist gives you. Many bite-correction elastics are worn full time and removed only for eating and brushing; others are night-only, or used for a specific stage of treatment. The schedule is chosen to suit your particular mechanics, which is why partial wear does more than simply slow things down — it can move teeth in the wrong balance and leave the bite only partly corrected by the planned finish date.

What happens if you forget to wear them?

Restart the prescribed pattern as soon as you remember, and do not double up to make up for lost time unless you have been specifically told to. Doubling elastics overloads the teeth and roots with excessive, uneven force rather than speeding anything up. Occasional missed hours are common and rarely derail a treatment plan, but a repeated pattern of non-wear will show in the result. Be honest about it at appointments so the orthodontist can adjust the mechanics or the timeline accordingly.

How do elastics work with clear aligners?

Clear aligners can carry elastics using precision cuts moulded into the tray edge, or small buttons and hooks bonded directly to the teeth for the elastic to hook onto. This lets bite correction happen alongside straightening rather than needing fixed braces. The important condition is that elastics only pull effectively if the aligners themselves are worn for the prescribed number of hours each day and are seating fully against the teeth — an aligner that is not tracking cannot transmit the force where it is intended.

Can you eat and speak normally with elastics?

Most patients take their elastics out for meals and put a fresh pair in straight afterwards, since food stretches, contaminates and snaps the bands. Speech is briefly affected for some people but generally adapts within a few days, as the tongue learns to work around the bands. Mild tenderness is normal in the first days of wearing a new elastic pattern and settles as the teeth adapt. Broken hooks, elastics that pull unevenly from one side, or severe pain are not expected and should be checked by the orthodontist.

Why does compliance affect the final result?

Elastics are among the most patient-dependent parts of orthodontics: the orthodontist controls the wire and the brackets, but only you control how many hours the elastics are actually in. Because they are what corrects the relationship between the upper and lower arches, inconsistent wear produces a very specific outcome — teeth that look straight within each arch while the bite itself remains unfinished, with the overjet or underbite only partly reduced. That is the hardest problem to fix at the end of treatment, because it usually means extending the active phase rather than moving to retainers.

Useful related pages

This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist.