Orthodontics, the specialized field of dentistry focused on correcting improper bites and misaligned teeth, addresses both the dental and skeletal components of the mouth. The answer is nuanced: braces primarily move individual teeth, but they are frequently used in combination with other appliances designed to modify the growth or position of the jawbones. This combined approach allows orthodontists to achieve a harmonious alignment that affects both the smile and the facial profile.
The Primary Role of Braces
Traditional braces apply gentle, continuous force to individual teeth, not the jaw structure itself. This force is transmitted through a system of brackets bonded to the teeth, archwires that connect them, and small ties. The mechanism of tooth movement relies on a natural biological process known as bone remodeling.
Each tooth is anchored to the jawbone by the periodontal ligament (PDL). When pressure is applied by the braces, the PDL is compressed on one side of the tooth root and stretched on the other. This mechanical stress initiates a cellular response within the surrounding alveolar bone.
Specialized cells called osteoclasts break down bone tissue on the side of pressure, creating space for the tooth to move. Simultaneously, osteoblasts build new bone on the side of tension, stabilizing the tooth in its new position. This cycle allows the tooth to gradually shift through the jawbone, correcting crowding, spacing, and rotation.
Differentiating Dental and Skeletal Issues
To understand how alignment is achieved, it is necessary to distinguish between two categories of misalignment: dental and skeletal. Dental malocclusion refers to issues with the position of the teeth where the underlying jaw structure is correctly sized. This includes problems like crowded or rotated teeth, or minor bite irregularities.
A typical Class I malocclusion means the back molars have a normal bite relationship, but the front teeth are misaligned or overlapping. Braces alone are generally sufficient to correct these types of dental issues by repositioning the teeth within the existing jaw architecture.
Skeletal discrepancy involves a size, shape, or positional mismatch between the upper jaw (maxilla) and the lower jaw (mandible). These issues are often genetic and require more than just tooth movement. A Class II discrepancy (overbite) occurs when the lower jaw is recessed relative to the upper jaw. Conversely, a Class III discrepancy (underbite) involves a lower jaw positioned too far forward. Braces are typically used to align the teeth, but they cannot correct the underlying bone misalignment without assistance.
Appliances Used for Non-Surgical Jaw Correction
For patients who are still growing, orthodontists utilize functional appliances to modify the development of the jawbones non-surgically. This approach guides growth to correct skeletal discrepancies by harnessing the body’s natural developmental potential.
Functional Appliances
The palatal expander is used to widen a narrow upper jaw. This appliance applies lateral force to gently separate the midpalatal suture, increasing the width of the upper dental arch. For Class II or Class III discrepancies, functional appliances like the Herbst or Mara device are fixed to the teeth and encourage the lower jaw to grow into a more forward position.
Elastics (Rubber Bands)
Removable elastics are frequently worn by patients with braces. These bands attach to hooks on the upper and lower braces, applying continuous force between the jaws to improve the bite relationship. By directing force across the dental arches, elastics help shift the teeth and influence the position of the jaws relative to each other, improving the overall skeletal balance.
When Orthognathic Surgery Becomes Necessary
Non-surgical methods are limited by the severity of the skeletal discrepancy and the patient’s age. Once facial bones are fully developed, typically in late adolescence or adulthood, growth modification is no longer possible. In these instances, orthognathic surgery, or jaw surgery, is required to correct severe skeletal misalignments.
The primary indications for surgery are functional deficits, such as difficulty chewing or speaking, and significant facial imbalance that cannot be resolved by moving the teeth alone. The surgery involves repositioning the maxilla, mandible, or both, by cutting the bone and fixing it into a new, corrected position with plates and screws.
This surgical approach is known as “Surgical Orthodontics” and is performed in conjunction with braces. Braces are worn before the operation to align the teeth within each jaw so that they fit together precisely once the jawbones are surgically repositioned. Braces are then worn for a period after the surgery to refine the final bite relationship.