Orthodontic bonding is the foundational process in traditional braces treatment, which involves affixing small appliances to the teeth to facilitate movement. This method uses a specialized dental adhesive, often a composite resin, to securely attach hardware like brackets and tubes to the tooth enamel. The hardware acts as a handle through which the orthodontist threads a flexible archwire, allowing the application of continuous, controlled pressure. A strong, durable bond is necessary for the archwire to transmit the precise force required to gradually shift the teeth into their correct positions.
The Primary Bonding Zone: Front and Middle Teeth
Brackets are most commonly bonded directly onto the visible, outer surface of the teeth, extending from the front of the mouth toward the back. This primary bonding zone includes the eight incisors and canines, which are the teeth used for biting and tearing food. The placement continues further back to include the first and second premolars, sometimes called bicuspids, which are located just before the large molars.
The flat surface allows for a strong, reliable bond using composite resin, which is cured with a special light. Accurate positioning is crucial because the bracket acts as a guide, dictating the exact angle and orientation of the tooth’s movement. Bonding brackets directly to these teeth allows for sophisticated individual control, enabling movements like rotation, tipping, and root torque. This technique is also preferred for aesthetic reasons, as it avoids the bulkier appearance of a full band encircling the tooth.
Distinction for Rear Teeth: Bands and Tubes on Molars
The large back teeth, the molars, represent the main exception to the rule of direct bracket bonding in traditional orthodontics. Molars are subjected to the greatest chewing and biting forces, known as the occlusal load, making them prone to bracket failure if only a standard bonded bracket is used. To withstand this immense pressure and provide a secure anchor for the archwire, orthodontists typically use hardware that encircles the entire tooth.
Molar bands are precisely fitted metal rings cemented around the entire circumference of the tooth, offering the most stable anchorage. A small metal sheath, or buccal tube, is welded onto the outer side of the band to hold the archwire. Alternatively, a buccal tube can be bonded directly onto the molar surface, though bands are often favored on the first molars for maximum security. These first molars serve as the primary anchor points from which the archwire exerts force to move all the other teeth.
Specialized Placement Methods
Lingual Braces
Lingual braces are a highly aesthetic option where the brackets are bonded to the inner surface of the teeth, facing the tongue. This placement makes the appliance virtually invisible from the outside. However, it presents unique challenges due to greater anatomical variation and limited access on the tongue-side of the teeth. Customized brackets and indirect bonding methods are often required to ensure accurate placement on this curved surface.
Attachments and Buttons
Clear aligner therapy relies heavily on bonding, using small composite handles called attachments rather than traditional brackets. These tooth-colored resin bumps are temporarily bonded to specific teeth, providing the aligner tray with a surface to grip and apply necessary force for complex movements like rotation or extrusion. For correcting bite discrepancies, tiny metal or ceramic buttons may be bonded to the tooth surface to serve as fixed anchors for rubber bands. Both attachments and buttons are removed without damage once treatment is complete.
Temporary Anchorage Devices (TADs)
The Temporary Anchorage Device (TAD) is a small, screw-like implant, often made of titanium alloy. TADs are not bonded to the tooth surface but are placed into the alveolar or extra-alveolar bone of the jaw. These mini-screws create a fixed, non-moving anchor point, providing a stable base that allows the orthodontist to move specific teeth without causing unwanted reciprocal movement in other teeth. TADs are used in complex cases to achieve movements that might otherwise require more invasive procedures or cumbersome external headgear.