Braces are complex medical devices, not just simple metal wires, and they rely on many small, specialized components working together to straighten teeth. While the small square parts on the front teeth are widely known as brackets, the components on the back teeth, specifically the molars, are structurally and functionally different. This difference often leads to confusion, as the hardware on the rear molars does not look or act like the standard attachments on the front of the mouth.
The Molar Attachment Terminology
The component attached to the molars at the very back of the dental arch is most commonly called a buccal tube. This attachment is positioned on the cheek-side surface of the molar, which is the “buccal” side in dental anatomy. Its primary purpose is to serve as the termination point for the main archwire that runs through the entire set of braces.
Sometimes, the buccal tube is bonded directly onto the tooth surface using a strong dental adhesive. Alternatively, the tube may be pre-welded to a thin, custom-fitted metal ring known as a molar band. This molar band is cemented around the entire circumference of the tooth, which provides a very secure attachment method often preferred for cases requiring greater force or for teeth that have been restored.
Why the Back Piece Is Unique
The buccal tube is structurally distinct from the standard bracket found on the incisors and canines. A typical bracket has an open, horizontal slot on its face where the archwire is placed and then secured with a small elastic or wire tie. The buccal tube, however, is designed as a hollow, closed or semi-closed channel. Instead of the wire being tied into a slot, the end of the archwire is threaded directly through the opening of the buccal tube until it reaches the end. This tubular design means the archwire is fully contained at this point.
The Function of Buccal Tubes
The molar attachment serves a fundamental mechanical function as the anchor or foundation for the entire system of forces that will move the other teeth. Molars are the largest teeth with the deepest roots, making them the most stable points in the mouth from which to apply force. The robust nature of the molar band or bonded tube allows it to withstand the heavy forces required to move the smaller, front teeth.
The buccal tube ensures that the tension generated by the archwire is applied effectively throughout the arch. By providing a stable, fixed end, the tube prevents the archwire from simply slipping out and allows the restorative force of the wire to be directed at the teeth that need movement.
This design is also crucial for controlling specific, complex movements like torque and rotation on the molars themselves, which is essential for correcting the bite. Many buccal tubes also include small hooks, which serve as attachment points for elastics or rubber bands used to correct the alignment of the upper and lower jaws.