Braces are an effective method for making teeth straight. Orthodontic braces are specialized appliances that apply gentle, consistent pressure to the teeth, gradually moving them into a more desirable position. This process addresses aesthetic concerns like crookedness and spacing, while also correcting functional problems with the bite. The movement relies on a controlled biological response within the jawbone, resulting in a permanent structural change that aligns the teeth and improves oral health.
The Biological Process of Tooth Movement
The ability of braces to straighten teeth is rooted in the body’s natural capacity for bone remodeling. Teeth are not rigidly fused to the jawbone; instead, they are suspended within the socket by the periodontal ligament (PDL). When an orthodontic appliance applies a sustained, light force to a tooth, it creates areas of pressure and tension within this ligament.
The periodontal ligament converts mechanical stress into biochemical signals that initiate cellular activity in the surrounding alveolar bone. On the side where the appliance is pushing (the compression side), specialized cells called osteoclasts are activated. These cells begin bone resorption, dissolving bone tissue to create a path for the tooth to move.
Simultaneously, on the opposite side where the PDL is stretched (the tension side), osteoblasts are recruited. These cells deposit new bone tissue, filling the space left behind as the tooth shifts forward. This coordinated action of bone breakdown and bone formation allows the tooth to move slowly through the jawbone. A tooth typically moves about a millimeter per month during this controlled process.
Correcting Bite and Alignment Issues
While the visible result of braces is straight teeth, the primary functional goal of orthodontic treatment is to correct malocclusion, or a “bad bite.” Malocclusion refers to any misalignment between the upper and lower dental arches when they come together. Correcting this involves establishing proper occlusion, which is the precise fit of the upper teeth over the lower teeth.
One common issue is a Class II malocclusion, often described as an overbite, where the upper front teeth are positioned forward of the lower teeth. Conversely, a Class III malocclusion, or underbite, occurs when the lower jaw and teeth protrude past the upper teeth. Braces, often combined with elastic bands or other auxiliaries, harmonize the relationship between the two arches, moving segments of teeth to establish a healthy bite.
Braces also address individual tooth problems like crowding, where there is insufficient space for all teeth, and spacing, where there are gaps between teeth. The treatment goal extends beyond aesthetics to ensure that the teeth meet correctly, distributing chewing forces evenly. Proper occlusion reduces abnormal wear on tooth surfaces, minimizes strain on the jaw joints, and makes the teeth easier to clean, promoting long-term oral health.
Different Types of Orthodontic Appliances
Orthodontic technology offers a variety of appliances, each designed to achieve the same biological movement but with different aesthetic and functional characteristics. Traditional metal braces remain an effective choice, consisting of stainless steel brackets bonded to the front of the teeth and connected by a wire that exerts the necessary force. They are durable, cost-effective, and reliable for correcting a wide range of complex alignment and bite issues.
For patients seeking a less noticeable option, ceramic braces use tooth-colored or translucent brackets that blend with the natural tooth shade. These function identically to metal braces, utilizing a wire and elastic ties to apply force. Lingual braces offer the highest level of discretion, as the brackets and wires are custom-fitted to the back, or tongue-side, surface of the teeth, making them virtually invisible from the outside.
A popular alternative to fixed appliances is a series of clear aligners, such as Invisalign, which are removable, custom-fabricated plastic trays. Each aligner tray is slightly different from the last, applying a gentle, incremental force to move the teeth over a prescribed period. This option appeals to many adults due to their nearly invisible appearance and the convenience of removing them for eating and oral hygiene. However, their effectiveness relies on the patient wearing them for the recommended 20 to 22 hours per day.
Maintaining the Straight Smile After Braces
Once the braces are removed and the teeth have reached their final, aligned positions, the active phase of treatment is complete, but retention begins immediately. The periodontal ligaments surrounding the teeth have a phenomenon known as “orthodontic memory,” causing them to exert a pulling force that encourages the teeth to shift back toward their original location. This unwanted movement is called relapse and is a natural biological tendency that must be counteracted.
To prevent relapse and allow the surrounding bone and gum tissues to stabilize around the newly positioned teeth, a retainer must be worn consistently. There are two primary categories of retainers: fixed and removable.
Fixed Retainers
Fixed retainers, or bonded wires, involve a thin wire glued to the tongue-side of the front teeth, providing permanent, non-removable support.
Removable Retainers
Removable retainers are generally worn full-time for an initial period and then transition to nightly wear for a long-term duration. Common removable types include the Hawley retainer, which uses an acrylic plate and metal wires, and the clear plastic retainer, which is a transparent, vacuum-formed tray that fits snugly over the teeth. Consistent, long-term retention is the most important factor in preserving the straight smile achieved through orthodontic effort.