Coil springs are small wound springs that slide onto the archwire of your braces to either push teeth apart or pull them together. They work alongside your brackets and wires as a targeted force system, handling specific tooth movements that the archwire alone can’t accomplish efficiently. There are two main types, open and closed, and each does the opposite job.
Open Coil Springs Create Space
An open coil spring is placed between two brackets on your archwire in a compressed state. As it tries to expand back to its original length, it pushes the teeth on either side apart, creating space in your arch. Think of it like a tiny compressed Slinky that wants to stretch out.
Your orthodontist will typically use an open coil spring when you have crowding and teeth need room to shift into proper alignment, when an unerupted tooth needs space to come in, or when molars need to be pushed further back in your mouth. They’re also used after a baby tooth is extracted before the adult tooth is ready to come in, keeping neighboring teeth from drifting into the gap.
Closed Coil Springs Close Gaps
Closed coil springs do the opposite. They look like tightly compressed little coils and are stretched between two points on your archwire. As the spring tries to return to its shorter resting length, it pulls teeth toward each other, closing a gap. This makes them useful for treating diastema (a visible gap between teeth, usually the front two) or for closing extraction spaces after a tooth has been removed.
A closed coil spring can also serve a simpler purpose: acting as a sleeve over the archwire to maintain a space or protect soft tissue from the wire itself.
Why Springs Instead of Rubber Bands
You might wonder why your orthodontist would use a metal spring when elastic chains (those small rubber band links) can also move teeth. The answer comes down to force consistency. Elastic chains lose their stretch quickly. They deliver a strong initial pull that drops off significantly within hours or days, meaning the force on your teeth is uneven over time.
Coil springs made from nickel titanium deliver a much steadier force. In lab testing, closed nickel titanium coil springs produce a consistent 75 to 90 grams of force over a 6-millimeter range, while open coil springs deliver 55 to 70 grams across 9 millimeters of compression. That steady, light pressure is closer to what’s considered ideal for moving teeth without damaging the roots or surrounding bone.
The key property making this possible is called superelasticity. A nickel titanium spring delivers roughly the same force whether it’s stretched a little or a lot. So as the gap closes or opens and the spring gradually returns to its resting shape, the pressure on your teeth stays relatively constant rather than dropping off like it would with rubber or stainless steel alternatives.
What They’re Made Of
Most modern orthodontic coil springs are made from a nickel titanium alloy. This material has two useful traits. First, it can be bent or stretched significantly and still snap back to its original shape, a property called shape memory. Second, it maintains a nearly flat level of force across a wide range of activation, which is the superelasticity mentioned above.
Some springs are made from stainless steel instead. These are stiffer and deliver a stronger initial force that drops off more sharply. Your orthodontist might choose stainless steel for shorter, more aggressive movements or use it as a passive space maintainer rather than an active tooth-mover. Nickel titanium is the preferred choice when slow, steady force over a longer distance is the goal.
What They Feel Like
When a coil spring is first placed or adjusted, you can expect pressure and soreness similar to what you feel after a regular wire adjustment. The teeth being targeted will feel tender, especially when biting down, for roughly two to five days. The discomfort is generally manageable with over-the-counter pain relief and soft foods.
Because coil springs sit on top of your archwire, they add a bit of bulk. Some patients notice the spring rubbing against the inside of their cheek or lip, particularly with open coil springs on the side teeth. Orthodontic wax placed over the spring usually solves this. The sensation tends to fade as the tissue in your mouth toughens up over the first week or so.
Keeping Coil Springs Clean
Coil springs are food magnets. The coiled wire creates tiny grooves that trap particles and plaque more easily than a smooth archwire. If you already have braces, you know the drill, but springs require extra attention.
Use a soft-bristled toothbrush angled toward the spring to brush along and around the coils after every meal. An interdental brush (those small cone-shaped brushes) is especially helpful for getting between the coils where a regular toothbrush can’t reach. A water flosser is another effective tool for blasting out debris lodged in or around the spring. Neglecting this area increases your risk of decalcification (those white spots on enamel) and gum irritation around the teeth the spring is acting on.
Possible Complications
Most coil spring treatment goes smoothly, but issues can come up. The most common is soft tissue irritation, where the end of the spring or wire pokes into the cheek, lip, or gum. This is the same type of poking you might experience with any part of braces, and your orthodontist can trim or reposition the wire to fix it.
In rare cases, a spring can dislodge from the archwire. One documented case involved a coil spring that came loose and migrated into the opening of a salivary duct inside the cheek, which required medical intervention to remove. While this is an extreme and uncommon scenario, it’s a good reason to contact your orthodontist promptly if you notice a spring has come loose or shifted out of place rather than trying to adjust it yourself.
Springs can also lose effectiveness over time. Exposure to saliva, varying food temperatures, and chewing forces can gradually alter the mechanical properties of nickel titanium, potentially reducing the consistency of force delivery after several weeks. This is one reason your orthodontist checks and sometimes replaces springs at regular adjustment appointments.
How Long You’ll Wear Them
The timeline depends entirely on how much space needs to be created or closed and how your teeth respond. For minor crowding where only 1 to 2 millimeters of space is needed, a coil spring might do its job in four to eight weeks. Closing a larger extraction gap or distalizing molars can take several months. Your orthodontist will monitor progress at each visit and remove the spring once the desired movement is achieved. In some cases, the spring stays in place passively after the movement is complete to hold the space until the next phase of treatment begins.