| Field | Value |
|---|---|
| ID | OA-0307 |
| Type | component |
| Category | component |
| Fixed/removable | removable (patient-placed and replaced daily) |
| Primary function | interarch force for sagittal and vertical correction |
| Malocclusion target | Class II; Class III; open bite; deep bite correction |
| Compliance required | yes — daily replacement required |
| Uses TADs | no |
Interarch elastics (rubber bands) are worn by the patient between upper and lower hooks, typically from upper canine hooks to lower first molar hooks (Class II configuration) or from lower canine hooks to upper first molar hooks (Class III configuration). Force is generated by the elastic's tendency to return to its unstretched diameter. Forces range from 2 oz to 6 oz depending on elastic size and diameter. Because elastic force decays over time, patients replace elastics every 8–24 hours. Compliance is the primary variable determining treatment success with interarch elastics. Combinations of elastic wear angles (anterior, posterior, vertical) allow fine-tuning of Class II/III correction and vertical control.
Interarch elastics generate force between upper and lower arches by stretching from a hook on one arch to a hook on the other. The elastic's tendency to return to its unstretched length creates a continuous force vector determined by the attachment positions. Force magnitude depends on elastic diameter (cross-section) and the distance between hooks (stretch).
Class II elastics (upper canine to lower molar): Distal force on upper anterior and mesial force on lower posterior; corrects Class II molar and canine relationship. The dominant use of interarch elastics.
Class III elastics (lower canine to upper molar): Opposite vector; corrects Class III tendency or mandibular prognathism in growing patients.
Vertical elastics (box or triangle patterns): Close anterior or posterior open bite by drawing the upper and lower teeth into contact in the affected segment.
Anterior triangle elastics: Correct midline discrepancies by asymmetric force application — one side Class II, one side vertical.
Finishing elastics: Light settling elastics worn at the end of treatment to improve interdigitation and fully seat the occlusion.
Elastics are specified by internal diameter (3/16", 1/4", 5/16") and force (2 oz, 3.5 oz, 6 oz). Smaller diameter = more stretch at a given interjaw distance = more force. Force levels for Class II correction: 3–4 oz per side. Vertical and settling elastics: 2–3 oz.
Elastic configuration (Class II, Class III, vertical) is dictated by the malocclusion. Force level is selected to achieve the desired tooth movement without causing excessive extrusion or discomfort. Patients replace elastics every 8–24 hours because force decays significantly within the first few hours.
Compliance is the primary variable — poorly compliant patients show treatment stagnation and erratic force application. Over-heavy elastics cause excessive extrusion of anchor teeth, opening the bite. Class II elastics applied late in treatment (on finishing wires) should be light to avoid disrupting occlusion after spaces are closed. Latex-free elastics are available for patients with latex allergy.
No lab fabrication. Manufactured by orthodontic suppliers (e.g., Ormco, American Orthodontics) in sizes classified by force (2 oz–6 oz) and inner diameter.
common configuration
correction or advancement
teeth; closes open bite
Class II and vertical forces
AP correction simultaneously
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Orthodontics 6th ed.](https://www.elsevier.com)
JCO](https://www.jco-online.com)
AJO-DO](https://www.ajodo.org)
compliance requirements, force decay.