Orthodontics is the branch of dentistry focused on correcting improper alignment of the teeth and jaws. Braces are the standard and most common appliance employed to achieve this goal. This treatment improves both the aesthetic appearance of the smile and the overall function of the bite.
The Biomechanics of Tooth Straightening
Braces move teeth by applying a constant, gentle force over an extended period of time. The system uses metal or ceramic brackets bonded directly to the teeth, which are then connected by a flexible archwire. This continuous, low-level pressure is the physical trigger that initiates the complex biological process of bone remodeling necessary for movement.
The sustained pressure compresses the periodontal ligament (PDL) on the side of the tooth root traveling forward. This compression signals specialized cells known as osteoclasts in the adjacent alveolar bone. Osteoclasts are responsible for bone resorption, meaning they dissolve the bone tissue directly in the path of the moving tooth.
Simultaneously, on the opposite side of the tooth where the PDL is stretched, tension is created. This tension activates osteoblasts, which are responsible for bone deposition. Osteoblasts lay down new bone material in the space created behind the moving tooth. This necessity for bone to be systematically broken down and rebuilt is why orthodontic movement must be slow and controlled, often progressing only about a millimeter each month.
Common Dental Issues Braces Correct
Braces correct issues related to the spatial relationship of teeth within the jaw. A common issue is dental crowding, which occurs when the jaw lacks sufficient room, causing teeth to overlap or become twisted. Conversely, some individuals experience spacing, where gaps exist between teeth, often leading to challenges in speaking or eating.
Braces correct malocclusions, which are defined as improper bites. An overbite happens when the upper front teeth overlap the lower front teeth excessively. Conversely, an underbite involves the lower teeth protruding significantly past the upper teeth. Correcting these relationships is important for proper chewing function, reducing abnormal wear on tooth surfaces, and improving overall oral hygiene.
Treatment Options and Duration
Patients seeking orthodontic correction have several appliance choices, depending on the complexity of the issue and aesthetic preference. Metal braces, which utilize stainless steel brackets and wires, are effective for correcting complex movements and are often the most economical choice. Ceramic braces function identically but use tooth-colored or clear brackets, offering a less noticeable appearance, though they require more careful maintenance.
Clear plastic aligners are custom-made, removable trays that incrementally shift the teeth and must be worn for 20 to 22 hours per day. While aesthetic and convenient, clear aligners are best suited for mild to moderate cases of misalignment and may not be appropriate for severe bite discrepancies.
The duration of active orthodontic treatment varies significantly based on the severity of the malocclusion and the individual patient’s biological response to the applied forces. For a typical case of moderate misalignment, treatment with braces or aligners usually lasts between 18 and 30 months. Shorter treatment times may be possible for minor cosmetic corrections, while severe skeletal or dental issues can require a longer commitment.
Following the active treatment phase, retention begins. Because the surrounding bone tissue needs time to fully solidify around the newly positioned roots, teeth have a natural tendency to drift back toward their original positions, a phenomenon known as relapse. This means the use of a retainer—either removable or permanently bonded to the back of the teeth—is required indefinitely to maintain the corrected alignment.