An Open Coil Spring (OCS) is a small, helical component made of materials like nickel-titanium or stainless steel. It is integrated into fixed orthodontic appliances (braces) and threaded onto the archwire connecting the brackets. The spring applies a deliberate, controlled force to specific teeth. This article explores the spring’s mechanical role, typical usage timeframe, and factors influencing the total duration of orthodontic treatment.
The Specific Role of Open Coil Springs
The primary mechanical purpose of an open coil spring is to create necessary space between teeth. Unlike the closed coil spring, which holds or closes space, the open coil spring exerts a continuous, gentle pushing force. It is compressed by the orthodontist between two brackets along the archwire, causing the spring to attempt to return to its original, uncompressed length.
This expansion applies pressure to the teeth, pushing them apart to make room in the dental arch. This technique is used to relieve severe crowding or to create space for a tooth blocked from erupting into its correct position. The spring delivers light, sustained forces, often 55 to 70 grams when using nickel-titanium, which is considered biologically optimal for safe tooth movement.
The continuous force stimulates the bone remodeling process, allowing the tooth to gradually move through the jawbone. This process is known as distalization, moving teeth backward, or it can simply open a gap for alignment purposes. The spring’s design ensures the force remains consistent over a large distance of activation, maximizing movement efficiency between appointments.
Typical Duration of Open Coil Spring Usage
The open coil spring is used only for a specific phase of the overall treatment, not as a permanent fixture. The duration the spring remains active is determined by the amount of space that needs to be created. For most patients, this active phase lasts for several months.
Many patients wear the open coil spring for approximately three to six months to achieve the required space. For example, if a patient needs three millimeters of space, the spring remains in place until that distance is achieved. The orthodontist monitors the movement, and once the teeth are sufficiently separated, the spring is removed, and the next phase of treatment begins.
Regular adjustment appointments are necessary during this period, usually every four to eight weeks. At these visits, the orthodontist may re-compress the spring to reactivate the force or replace it to maintain continuous pressure. Without these timely adjustments, the force dissipates, and tooth movement slows down or stops completely.
Factors Influencing Overall Treatment Timeline
Although the open coil spring phase lasts only a few months, the overall orthodontic treatment typically ranges from 12 to 36 months. This total duration is influenced by several patient-specific variables. The complexity and severity of the initial issue are the biggest determinants, as major crowding or significant bite issues require extensive movement and alignment time.
The patient’s biological response to the applied forces is another major factor. Younger patients, such as children and teenagers, often experience faster tooth movement because their developing jawbones are less dense than adult bone. The rate at which the bone surrounding the teeth remodels—a necessary process for movement—varies significantly among individuals.
Patient compliance also plays a role in keeping the timeline on track. Consistent adherence to proper oral hygiene prevents issues like gum inflammation, which can slow down movement. Avoiding foods that can break brackets or dislodge the archwire and attending all scheduled appointments are important for maintaining continuous progress.
Even after the open coil spring successfully creates the required space, the remaining treatment phases take a substantial amount of time. The newly created gaps must be closed, the teeth need to be precisely aligned, and the final bite must be settled into a stable, functional position. This finishing and detailing stage often takes significantly longer than the initial space-creation phase.