Traditional orthodontic braces correct misalignment and bite issues by applying controlled pressure to the teeth over time. This process relies on interconnected components, each with a specialized role in facilitating the biological movement of teeth within the jawbone. Understanding the terminology associated with these parts can demystify the mechanics of the treatment. The system is composed of foundational anchors, active wires, and various elastic accessories that work together to achieve a properly aligned smile.
Components Fixed to Tooth Surfaces
The foundational elements of the braces system are permanently attached to the tooth structure. The most recognizable are the brackets, which are small, square-shaped components typically made of metal or ceramic. Each bracket is individually bonded to the front surface of a tooth, acting as a fixed anchor point to receive and transmit forces from the archwire. They feature a central slot through which the archwire passes, guiding the direction of tooth movement.
On the back teeth, specifically the molars, different components are used for strength and stability. Buccal tubes are small, metal attachments bonded directly onto the molar’s outer surface, serving as the entry and exit points for the archwire. Like brackets, they contain a channel for the wire, but they are designed to manage the heavier forces applied to the molars.
Sometimes, when maximum anchorage is required, an orthodontist may use orthodontic bands instead of buccal tubes. These are thin, stainless steel rings that completely encircle the molar and are cemented into place. Bands are often preferred in cases where teeth have large fillings or for attaching complex auxiliary devices, offering a secure grip that minimizes the risk of detachment. Before placement, small elastic separators or spacers may be briefly inserted between the teeth to create the necessary space for the metal ring.
The Archwire and Ligature System
The archwire is the primary active component of the braces, generating the force that guides teeth into their correct positions. This wire conforms to the shape of the dental arch and is threaded through the slots of all the brackets and buccal tubes. Early in treatment, wires made from Nickel Titanium (NiTi) alloy are often used for their superelasticity and shape-memory. This allows them to return to their original shape even after being bent, applying light, continuous pressure.
As teeth move and alignment improves, the orthodontist progresses to stiffer materials like stainless steel or beta-titanium alloys. These alloys provide greater rigidity and are used in later stages for detailed positioning and to withstand heavier forces. The wire’s continuous force gently stimulates bone remodeling, the biological process where bone is removed and deposited, allowing the tooth to move.
To secure the archwire firmly within the bracket slot, small elastic O-rings or fine wire ties known as ligatures are used. Elastic ligatures, which can be clear or colored, are changed at every adjustment appointment because their force degrades over a few weeks. Wire ligatures, made of thin stainless steel, are used when a stronger, non-degrading hold is needed to prevent rotation or to apply a specific type of force.
A related component is the power chain, a continuous series of interconnected elastic loops that slide over multiple brackets. Unlike individual ligatures that only hold the wire in place, the power chain actively links several teeth together. These chains are primarily used later in treatment to close residual gaps or to consolidate spaces with a stronger, continuous pulling force.
Inter-Arch and Corrective Accessories
Beyond the fixed components and the archwire system, several removable accessories are used to perform complex corrections, particularly those involving the bite. The most common of these are elastics, often called rubber bands, which are significantly larger than the ligatures used on the brackets. These bands are worn by the patient and stretched between small hooks on the upper and lower braces.
These inter-arch elastics apply force between the two jaws to correct malocclusions, such as overbites or underbites, by adjusting how the upper and lower teeth meet. The patient is responsible for placing and changing these elastics multiple times daily. Consistent wear is essential for the timely correction of the bite, and the specific pattern is determined by the orthodontist to target the required jaw movement.
Other accessories are used for temporary, specific purposes during treatment. Separators are small elastic rings or metal springs placed between the molars for a few days to create space for bands. Orthodontic wax is a non-corrective accessory that patients apply to cover sharp edges of brackets or wires, providing temporary relief from irritation to the cheeks and gums. These supplementary parts ensure comfort and facilitate the placement of the more permanent components.