Braces are a common orthodontic treatment designed to straighten teeth and improve a person’s bite. This process guides teeth into optimal positions within the jaw. Understanding the underlying biological processes helps demystify how teeth move.
How Braces Move Teeth
Tooth movement orchestrated by braces relies on a fundamental biological process known as bone remodeling. When braces apply continuous, gentle pressure to a tooth, this force is transmitted through the tooth root to the surrounding bone. The periodontal ligament, a soft tissue connecting the tooth to the bone, experiences areas of compression and tension.
Where the periodontal ligament is compressed, blood flow reduces, signaling bone resorption. Specialized cells, osteoclasts, break down existing bone tissue at these sites. This bone removal creates space, allowing the tooth to shift in the direction of the applied force.
On the opposite side, where the periodontal ligament is under tension, blood flow increases, stimulating bone formation. Osteoblasts, bone-building cells, activate in these regions. These cells deposit new bone, solidifying and stabilizing the tooth in its new position. This continuous cycle of bone removal and deposition allows for controlled and gradual tooth movement.
Specific Tooth Movements
The question of whether braces “pull teeth down” directly relates to a specific orthodontic movement called intrusion. Intrusion refers to the movement of a tooth deeper into the alveolar bone, effectively making the tooth appear shorter or moving it further into the gum line. This movement is often necessary to correct conditions like a deep bite, where the upper front teeth excessively overlap the lower front teeth, or to level an uneven occlusal plane.
Conversely, the opposite movement, known as extrusion, involves moving a tooth out of the alveolar bone, making it appear longer. Extrusion might be employed to correct an open bite, where certain teeth do not make contact, or to bring a tooth into proper alignment with its opposing arch. Both intrusion and extrusion rely on specific forces to achieve precise vertical changes.
Beyond vertical movements, braces facilitate other types of tooth shifts. Tilting involves rotating the crown of a tooth around its root, changing its angle without moving the entire tooth bodily. Bodily movement, also known as translation, involves moving the entire tooth, root and crown, in a single direction through the bone. Rotation addresses teeth that are twisted, correcting their orientation within the arch.
Braces Components and Their Functions
Braces utilize several components that work in concert to apply the necessary forces for tooth movement. Brackets are small attachments, typically made of metal or ceramic, that are bonded directly to the surface of each tooth. These brackets serve as anchors, holding the archwire and transmitting its forces to the individual teeth.
The archwire is a crucial component, a thin metal wire that is threaded through the slots of the brackets. It acts as the primary source of continuous, gentle force, guiding the teeth along its predetermined shape. As the archwire seeks to return to its original form, it exerts pressure on the brackets, which in turn move the teeth into alignment.
Elastics, commonly known as rubber bands, are often used in conjunction with brackets and archwires. These small elastic bands are stretched between specific brackets on the upper and lower jaws, or between different teeth within the same jaw. They apply inter-arch or intra-arch forces, which are particularly effective for correcting bite discrepancies, such as an overbite or underbite, by encouraging the jaws to align properly.
In some cases, small springs may be incorporated into the orthodontic appliance. These springs can be placed on the archwire between two brackets to create space or close gaps between teeth. They can also apply specific intrusive or extrusive forces to individual teeth, allowing for highly targeted vertical adjustments.