How are braces attached?
The process of attaching braces to the teeth has changed significantly in the last 30 years. This is mainly due to the introduction of materials and methods that allow effective bonding of the braces directly to the enamel. As recently as 20 years ago, it was common for orthodontists to place bands, or rings, around each and every tooth. This provided an effective means of attachment, but tended to show quite a bit of metal.
In 1955, Dr. Buonocore published an article detailing his observation that conditioning the enamel before bonding increased the effectiveness of the attachment. It was found that the pretreatment caused microscopic changes in the enamel, allowing the bond materials to flow into the enamel, giving a micromechanical attachment. This concept was mostly used for dental fillings, but was later applied to orthodontics.
The back sides of the braces have a mesh design. When glue is placed onto the bracket and against the tooth, the combination of the conditioned enamel and the mesh base of the bracket provide a very good attachment.
The placement of the braces and the bonding procedure as used today generally follows these steps:
The teeth are polished with a non-flavored paste (this is similar to a dental polish after a cleaning).
A cheek retractor is placed to provide a dry field and make it easier to visualize the teeth.
The teeth are lightly air-dried, and the conditioner is placed onto the front surfaces of the teeth for about 30 seconds.
The conditioner is rinsed and the teeth are again dried using suction and air. A primer is painted onto the teeth.
The bonding cement is placed onto the back sides of the braces, which are then placed onto the teeth.
The brackets are placed in a very precise position onto the teeth, and excess bonding cement is removed.
If the bonding cement is light sensitive, a bright blue light is used to "cure" the glue. Some bonding agents do not require a light since they have a chemical cure.
The cheek retractor is removed and the wires are placed
The entire bonding procedure can take anywhere between 10-20 minutes. The length is primarily due to the time required to properly position the braces, and time required for the curing light. Recent advances in the curing lights have allowed use of LED lights, which narrow the wavelength of the light. This reduces the time needed to cure the glue. Older Halogen lights require about 15-20 seconds for each bracket, whereas an LED light would require only half of the time. Plasma lights require even less time (about 3 seconds per bracket).
Bonding braces is quite painless, although the length of time required for the procedure is perhaps a bit annoying. The cheek retractors, which are so essential to a successful bonding procedure, can stretch the cheeks and lips and make the whole mouth feel very dry when the bonding is completed. The lips and cheeks recover very quickly, however, and the dryness can be remedied with a rinse (which also helps to remove the bad taste).
A dry field is very important since the materials used for bonding require a clean enamel surface. Many of the primers and some types of glue are water tolerant (hydrophilic), but do not perform very well with saliva contamination. Proteins in saliva have a tendency to bind very quickly to the enamel surface and forms a layer know as a pellicle. The pellicle interferes with proper bonding. Consequently, the enamel surface needs to remain protected from the tongue, cheeks, and lips during the entire bonding procedure.
Many orthodontists will still place bands (rings) on the back molars. The bands were the treatment of choice for all teeth as recently as 30+ years ago. Despite the advances in the bonding materials and effectiveness, many find there are still advantages to using bands on the molar teeth.
An advantage of using molar bands includes an increased stability of attachment on a large tooth in a very highly active part of the mouth. They also provide additional attachments on the tongue side of the band, as well as attachment tubes for headgear and other appliances. The process of placing bands on the molars involves the following:
Separators are placed 1 week prior to the appointment of band placement.
The separators are removed, revealing space between the back molar teeth.
Bands, which come in a variety of sizes, are selected to fit each individual tooth.
A bite stick is used to help properly place and position the band on the tooth. By having the patient bite together with the stick, less strain is placed on the jaw while positioning the band. The orthodontist will first position the stick, and then let the patient know when and how hard to bite.
Once the bands are selected and fit to the molars, they are removed and dried.
The inner portion of the band is lined with band cement, and then it is positioned on the tooth
If the cement is light sensitive, a light will be used to cure it.