| Field | Value |
|---|---|
| ID | OA-0137 |
| Type | functional_appliance |
| Category | functional_appliance |
| Fixed/removable | fixed |
| Primary function | Class II correction via continuous spring force |
| Malocclusion target | Class II malocclusion; overjet reduction |
| Manufacturer | 3M (Solventum) |
| Period | modern |
| Status | current |
| Uses TADs | no |
The Forsus Fatigue Resistant Device is 3M's most widely-used fixed Class II corrector, with over one million patients treated since its introduction. Unlike the Herbst (piston-cylinder) or PowerBar (bar-socket), the Forsus uses a coaxial spring mechanism that attaches to the upper molar's headgear tube and the lower archwire. The coaxial spring design was specifically engineered to resist fatigue failure — a critical advantage over simpler spring designs that lose force over time. The appliance delivers light, continuous Class II correction without patient compliance. Two module designs are available: the L-pin module (flexible installation options) and the EZ2 module (automatic anti-pivot, consistent installation).
The coaxial spring (two interlocking spring coils) attaches superiorly to the headgear tube on the upper first molar band and inferiorly to a push rod that connects to the lower archwire near the lower first premolar. The spring delivers a continuous protrusive force on the lower arch and a distalizing force on the upper arch — correcting Class II relationship. The coaxial design maintains relatively constant force throughout the range of jaw movement, unlike single coil springs that rapidly lose force as they shorten. Treatment time: 6–9 months.
Class II correction in growing patients during comprehensive fixed appliance treatment; patients where compliance is a concern; practices seeking a reliable, proven fixed Class II corrector; adolescent patients with significant overjet; use during the final phase of leveling and alignment when brackets are bonded.
Requires full upper and lower bracket bonding before placement; cheek irritation can occur (EZ2 module reduces pivot toward cheek); lower incisor proclination is a common side effect; appliance breakage (spring fatigue) possible — FRD design reduces but does not eliminate this; not for adults without growth.
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Forsus is manufactured by 3M (Solventum) and purchased by practices. No lab fabrication required for the Forsus mechanism. Standard molar bands used for the upper attachment may be lab-fabricated.
most common current Forsus version
directly into headgear tube without separate sleeve
combined with Forsus for simultaneous deep-bite management
effect with minimal dental anchorage loss
Forsus; less stiff, more patient comfort
— 3M](https://www.3m.com/3M/en_US/p/d/b5005051009/)
— 3M](https://multimedia.3m.com/mws/media/823065O/forsus-fatigue-resistant-device-treatment-guide.pdf)
Tribune](https://www.dental-tribune.com/prod/3m-forsus-fatigue-resistant-device/)
EZ2 module, >1 million patients, fatigue resistance design.