One may ask “how did we get to where we are today?” when considering all the modern types and styles of braces. With all the advancements and changes that take place routinely in the field of orthodontics, braces have certainly changed over the past few years. There is evidence of orthodontic treatment being done well before the meridian of time, but it became more widespread and less barbaric in the mid 1800’s when Dr. Edward Angle started refining braces so the doctor could control tooth movement 3 dimensionally. He initially did this with a “Pin and Tube” type appliance that used bands around each tooth which had a tube welded on vertically, and a base wire that followed the arch or semi-circle of the teeth and jaws with vertical pins soldered on the wire that corresponded to each tube welded onto a band. The bands would be fit precisely to the form of each tooth, then cemented in place. The wires would be tied into place once the pins were engaged into each tube.
Dr. Angle encountered some obvious problems and complications with the “Pin and Tube” system and did a redesign. The new system was called the “Ribbon Arch” and used a rectangular wire that fit in a vertical slot that was cut into the tube from the old “Pin and Tube” system. The rectangular wire was bent around the smaller wire dimension to form an arch form for the teeth to follow, and it was pinned or tied into the tube. The “ribbon Arch” system was better, but still had some problems. It was also difficult to place and secure in the vertical tube braces. To solve this, the next generation of braces turned the slot and the wire 90 degrees. The slot became horizontal rather than vertical, which made wire insertion much easier. The wire was now bent around the short dimension of the rectangular wire and Dr. Angle called this the “Edgewise System.” To hold the wire in the braces, “tie wings” were created by placing undercuts on opposing sides of the wire slot and very fine “ligature” wires were used to ligate or tie the arch wires in place.
The edgewise system has been in place since the late 1800’s, but has undergone several upgrades and design changes to the basic system. The Edgewise Appliance in one form or another is the most widely used orthodontic system in use today. It has become the worldwide standard for brace systems.
Now that we know what braces are, lets learn what they do, how they work and what part the braces play in orthodontic treatment. In order for the teeth to move, a pressure must be applied to the tooth. The tooth responds to the pressure by moving in harmony with the force vector, or direction of force. In the past, there was no way to secure a brace directly to the tooth, so they were welded onto bands that were fit like rings around every tooth. Bands are still used with some orthodontic appliances and on the back teeth because they are much more durable and less prone to breakage. Fortunately, in the late 70’s and early 80’s composite resins that are biocompatible with the tooth structure were developed and started being used for dental fillings and adhesives. These composites were refined and developed to glue or bond the braces directly to the teeth. In today’s modern orthodontic practice, the majority of the braces are bonded directly to the teeth and bands are rarely, if ever, used on any of the front teeth.
Once the braces, or “brackets” could adhere to the teeth, treatment became much more aesthetic and the application of the braces much easier on the patients. It is important to have a good bond between the tooth and the bracket so that the bracket is capable of transmitting sufficient force to the tooth so that it will respond and move as intended.
The braces, or brackets provide a slot for the arch shaped wires to engage and exert a force to move the teeth in the desired direction. The braces are basically a handle, or stable point, that allows the wires to become effective in moving the teeth. Tooth movement is really all about the wires, not about the braces. It is the wire that produces the force to move the teeth, but it is the interface between the wire and the brace that dictates how the force will be applied and controls how the tooth will move.
How the brace and the arch shaped wire interface and work together is dependent on several different variables. One variable is the position of the bracket on the tooth. For example, if the brace is placed closer to the edge of the tooth, the wire will push the tooth into the gum and make it appear shorter. If the brace is placed at an angle on the tooth, the crown of the tooth will tip to one side and the root will tip in the opposite direction. If the brace is placed off center then it will cause a rotation of the tooth. These bracket placement errors can be overcome and compensated for by bending the arch shaped wire. It is rare to find that every brace is placed in the exact right place on every tooth from the beginning of treatment. Often, because of the crowding, it is impossible to place the bracket in the proper position, so it needs to be repositioned later in treatment once the tooth is in a better position and there is access to the location where the brace belongs.
The braces have many variations in their design and the orientation of the wire slot. Each of the variations serves a unique purpose. One of the most significant initial changes made to braces was to build the individual root angle, root tip, and tooth thickness compensation.
Attachments have been developed and refined over the years so that there are several shapes, orientations, and sizes used to provide optimal leverage for the plastic to accomplish the desired individual tooth movements. Some tooth movements are accomplished very effectively with a single attachment on the tooth, while other movements require multiple attachments on the same tooth so they can work in concert with each other to efficiently move the tooth and position the root as desired. The attachments have become an integral part of clear aligner treatment, and a necessary component for achieving excellent treatment results.
Although the bonding adhesives used to form the attachments are strong and durable, they may wear, chip, fracture, or dislodge and fall off during treatment. If an attachment becomes worn or chipped, it will be less than optimally effective in accomplishing the desired tooth movements. If an attachment falls off, the aligner may be unable to accomplish further tooth movement, depending on the tooth involved and what movements remain in treatment. Because the loss of an attachment can have an adverse effect on treatment, it is important to report any loss of attachments to the orthodontist as soon as possible. It is helpful if you can tell them what tooth or teeth are missing their attachments. The orthodontist will be in a better position to understand how urgent it is to repair the breakage, and what else may need to be done in conjunction with replacing the missing or damaged attachments. The staff will give you an appointment to make the needed repairs or replacements.
One of the differences between the braces and aligners and how they work to straighten the teeth is that with the braces, the details of tooth position is determined by where the braces are placed on the surface of the teeth, and in relation to the brace positions on the adjacent teeth. With clear aligners, the position that the attachments are placed on the teeth has no bearing on how the teeth are moved or ultimately positioned. The attachments are usually placed to gain maximum effect for the movement they are facilitating. Typically, the attachments are placed closer to the edges of the teeth rather than closer to the gums because when they are placed close to the gums there is very little aligner material at the gum level to grip the attachment and this weakens the grip of the aligner on the attachment.
As one would expect, the bigger the attachment, the more effective it will be as a handle for the aligner to grab a hold of. Cosmetics and irritation are limiting factors to the size of the attachments. You do not want to have an attachment that is large and irritating when you can accomplish the required tooth movement with an attachment that is less intrusive. There is definitely a balance to be had in the size and positioning of attachments.