| Field | Value |
|---|---|
| ID | OA-0193 |
| Type | component |
| Category | component |
| Fixed/removable | fixed (on archwire) |
| Primary function | push teeth apart; open interproximal space |
| Uses TADs | no |
An open coil spring (compression coil) is a helical spring threaded onto the archwire between two adjacent brackets. In its natural state, the spring is longer than the space between the brackets; when compressed onto the wire, it exerts a continuous expansion force that pushes the adjacent teeth apart. Used to: create space for a missing tooth before implant or prosthetic replacement, open a collapsed extraction space, provide space for impacted tooth eruption, or redistribute spacing. NiTi open coils provide lighter, more constant forces; SS open coils provide heavier, less constant forces.
An open coil spring rests on the archwire in a compressed state between two brackets or stops. As the spring tries to return to its natural length, it pushes the adjacent teeth apart, creating space. Force magnitude is determined by the spring's compression (the difference between its natural length and its compressed length) and the spring's stiffness (wire gauge and coil diameter).
Space opening for impacted or missing teeth: The most common use — an open coil spring between a canine and first premolar pushes them apart to create room for an impacted canine or to open space for a prosthetic implant.
Molar protraction: Open coil springs placed distal to a premolar and mesial to a molar can push the molar distally for Class II correction (in combination with TAD anchorage).
Re-creating space after premature space loss: In mixed dentition cases where an extraction site has partially closed, open coil springs reopen the space before prosthetic replacement or transplantation.
Spring selection depends on the required force (approximately 50–150 g for tooth movement) and the space to be opened. A spring compressed to 2/3 of its natural length delivers consistent force in the biological range. Springs are available in stainless steel, NiTi (constant force across compression), and TMA.
Anchorage control is critical — without adequate anchorage, the spring pushes the anchor tooth as much as the target tooth. Poor oral hygiene around springs leads to plaque accumulation and gingival irritation. Springs can be dislodged if the archwire is not secured at both ends.
No lab fabrication. Manufactured product; placed chairside.
Appliances that incorporate this component. ★ = fabricated by Clear Fusion Lab.
appliance
appliance
TAD-based distal jet
TAD-supported pendulum appliance
space opening; sizes 0.010"×0.030" typical
for heavy space opening or anchorage
passive length for push force vs. longer for engagement
opening; full-length coil for multiple spaces
cartridge; calibrated force delivery for space opening
JCO](https://www.jco-online.com)
Guide](https://www.rmortho.com)
Sirona](https://www.dentsplysirona.com/orthodontics)