Dental braces

Editor in Chief: Berna Zorkun DMD [mailto:bernazorkun@gmail.com]

Overview
Dental braces (also known as orthodontic braces) are a device used in orthodontics to correct alignment of teeth and their position with regard to bite. Braces are often used to correct malocclusions such as underbites, overbites, cross bites and open bites, or crooked teeth and various other flaws of teeth and jaws, whether cosmetic or structural. Orthodontic braces are often used in conjunction with other orthodontic appliances to widen the palate or jaws, create spaces between teeth, or otherwise shape the teeth and jaws. Most orthodontic patients are children or teenagers, however, recently, more adults have been seeking orthodontic treatment.

History
In the mid-18th century the French physician Pierre Fauchard (credited as the father of modern dentistry) witnessed and treated several dental deformities very common among citizens in Paris during the pre-revolutionary France.

Historians believe that two different men deserve the title of being called "the Father of Orthodontics." One man was Norman W. Kingsley, a dentist, writer, artist, and sculptor, who wrote his "Treatise on Oral Deformities" in 1880. Kingsley's writings influenced dental science greatly. Also deserving credit is dentist J. N. Farrar, who wrote two volumes entitled "A treatise on the Irregularities of the teeth and their corrections". Farrar was very good at designing brace appliances, and he was the first to suggest the use of mild force at timed intervals to move teeth.

The American dentist Edward Angle is widely regarded as the father of modern orthodontics. Practising in the late nineteenth and early twentieth centuries, his eponymous classification of dental arch relationships is used worldwide. His textbook, "Treatment of Malocclusion of the Teeth" was first published in 1887. It went into seven much revised editions and laid the foundation of the modern specialty. After tenure as professor of orthodontics in two medical schools, he went on to found his School of Orthodontia in 1910. He designed several fixed orthodontic appliance systems including the ribbon arch and then the edgewise appliance. This has evolved into the sophisticated pre-adjusted and self-ligating systems used by the great majority of orthodontists today.

How braces work
Teeth move through the use of force. The force applied by the archwire pushes the tooth in a particular direction and a stress is created within the periodontal ligament. The modification of the periodontal blood supply determines a biological response which leads to bone remodelling, where bone is created on one side by osteoblast cells and resorbed on the other side by osteoclasts.

Two different kinds of bone resorption are possible. Direct resorption, starting from the lining cells of the alveolar bone, and indirect or retrograde resorption, where osteoclasts start their activity in the neighbour bone marrow. Indirect resorption takes place when the periodontal ligament has become acellular (necrosis or hyalinization), for an excessive amount and duration of compressive stress. In this case the quantity of bone resorbed is larger than the quantity of newly formed bone (negative balance). Bone resorption only occurs in the compressed periodontal ligament. Another important phenomenon associated with tooth movement is bone deposition. Bone deposition occurs in the distracted periodontal ligament. Without bone deposition, the tooth will loosen and voids will occur distal to the direction of tooth movement.

A tooth will usually move about a millimeter per month during orthodontic movement, but there is high individual variability. Orthodontic mechanics can vary in efficiency, thus explaining a wide range of response to orthodontic treatment.

Procedure
Orthodontic services may be provided by any licensed dentist trained in orthodontics. In North America most orthodontic treatment is done by orthodontists, dentists specializing in diagnosis and treatment of malocclusions&mdash;malalignments of the teeth, jaws, or both. A dentist must complete 2–3 years of additional post-doctoral training to earn a specialty certificate in orthodontics. There are many general practitioners who also provide orthodontic services.

The first step is to determine if braces are suitable for the patient. The doctor consults with the patient and inspects the teeth visually. If braces are appropriate, a records appointment is set up where X-rays, moulds, and impressions are made. These records are analyzed to determine the problems and proper course of action. Typical treatment times vary from six months to six years depending on the complexity and types of problems. Orthognathic surgery may be required in extreme cases.

Teeth to be braced will have an etchant applied to help the cement bond to the surface of the tooth. A bracket will be applied with dental cement, and then cured with light until hardened. This process usually takes a few seconds per tooth. If required, orthodontic spacers may be inserted between the molars to make room for molar bands to be placed at a later date. Molar bands are required to ensure brackets will stick. Bands are also utilized when dental fillings or other dental work make securing a bracket to a tooth unfeasible.



An archwire will be threaded between the brackets and affixed with elastic or metal ligatures. Archwires in the past had to be bent, shaped, and tightened frequently to achieve the desired results. Modern orthodontics makes frequent use of nickel-titanium archwires and temperature-sensitive materials. When cold, the archwire is limp and flexible, easily threaded between brackets of any configuration. Once heated to body temperature, the archwire will stiffen and seek to retain its shape, creating constant light force on the teeth.

Elastics are used to close open bites, shift the midline, or create a stronger force to pull teeth or jaws in the desired direction. Brackets with hooks can be placed, or hooks can be created and affixed to the archwire to affix the elastic to. The placement and configuration of the elastics will depend on the course of treatment and the individual patient. Elastics are made in different diameters, sizes, and strengths.

In many cases there is insufficient space in the mouth for all the teeth to fit properly. There are two main procedures to make room in these cases.

One is extraction: teeth are removed to create more space.

The second one is expansion: the palate or arch is made larger by using a palatal expander. Expanders can be used with both children and adults. Since the bones of adults are already fused, expanding the palate is not possible without surgery to unfuse them. An expander can be used on an adult without surgery, but to expand the dental arch, and not the palate.

For some patients, Invisalign might be a viable alternative to braces. The Invisalign system uses a series of clear plastic trays to move teeth into their position over a length of time. This system is not recommended for more difficult cases, or for people whose last molars have yet to erupt. However, one of the disadvantages of Invisalign is that it usually requires a longer treatment time, especially because the appliance is removable, whereas conventional braces are always working because they are fixed to the patient's teeth. This usually allows for a faster treatment because the patient is not tempted to remove the appliance, as they may be with Invisalign. Patients may need post-orthodontic surgery, such as a fiberotomy or alternatively a gum lift, to prepare their teeth for retainer use and improve the gumline contours after the braces come off.

Each month or so the braces must be tightened. This helps shift the teeth into the correct position. When they get tightened the orthodontist takes off the colors, and the wire is very loose. The patient gets to choose a color, and then the orthodontist tightens them. This may cause some discomfort, which is normal.

Post-treatment
In order to avoid the teeth moving back to their original position, retainers may be worn once treatment with braces is complete.

Even before getting braces some people receive spacers or separators. These go on the top and bottom back molars. Patients will wear them until their banding appointment. Spacers are small elastics placed between your molars. They will make space for the metal molar bands that will be fitted to the patient's mouth when the wires are added.

Surgery can also follow treatment with braces.

Some patients find braces can be uncomfortable in the mouth, which can affect the post-treatment of patients with braces.

Retainers
Retainers are required to be worn once treatment with braces is complete. The orthodontist will recommend a retainer based on the patient's needs. If a patient does not wear the retainer as recommended, the teeth might move towards their original position (relapse).

A Hawley retainer is made of metal hooks that surround the teeth and are enclosed by an acrylic plate shaped to fit the patient's palate. An Essix retainer is similar to Invisalign trays. It is a clear plastic tray form-fitted to the teeth and stays in place by suction. A bonded retainer is a wire permanently bonded to the lingual side of the teeth (usually the lower teeth only).

Pre-finisher
If a person's teeth are not ready for a proper retainer, the orthodontist may prescribe the use of a pre-finisher. This rubber appliance similar to a mouthguard fixes gaps between the teeth, small spaces between the upper and lower jaw, and other minor problems that could worsen. These problems are small matters that dental braces cannot fix.

The pre-finisher is molded to the patient's teeth by use of severe pressure to the appliance by the person's jaw. The pre-finisher is then worn for the prescribed time, with the user applying force to the pre-finisher in their mouth for ten to fifteen seconds at a time. The goal is increasing the "exercise" time, time spent applying force to the appliance. Like the retainer, the pre-finisher is not a permanent addition to one's mouth, and can be moved in and out of the mouth.

Surgery
Orthognathic surgery is surgery to correct conditions of the jaw and face, including after treatment with braces. For instance, the origin of uneven teeth can actually be an uneven growth of the jaws. Then, the teeth must first be properly positioned with braces, creating an obvious prognathism or retrognathism. It is this condition that orthognathic surgery finally fixes.

Complications and risks
Plaque forms easily when food is retained in and around braces. It is important to maintain proper oral hygiene by brushing and flossing thoroughly when wearing braces to prevent tooth decay, decalcification, or unpleasant color changes to the teeth.

There is a small chance of allergic reaction to the latex rubber in elastics or to the metal used in braces. In rare cases it results Ulcerative Colitis. Latex-free elastics and alternative metals can be used instead. It is important for those who believe that they are allergic to their braces to notify the orthodontist immediately.

Mouth sores may be triggered by irritation from components of the braces. Many products can increase comfort, including oral rinses, dental wax or dental silicone, and products to help heal sores.

Braces can also be damaged if proper care is not taken. It is important to wear a mouthguard to prevent breakage and/or mouth injury when playing sports. Chewing gum and certain sticky or hard foods, such as raw carrots, large hard pretzels, and toffee should be avoided because they can damage braces. Frequent damage to braces can prolong treatment.

In the course of treatment orthodontic brackets may pop off due to the forces involved, or due to cement weakening over time. The orthodontist should be contacted immediately for advice if this occurs. In most cases the bracket is replaced.

When teeth move, the end of the arch wire may become displaced, causing it to poke the back of the patient's cheek. Dental wax can be applied to cushion the protruding wire. The orthodontist must be called immediately to have it clipped, or a painful mouth ulcer may form. If the wire is causing severe pain, it may be necessary to carefully bend the edge of the wire in with a spoon or other piece of equipment (i.e. tweezers) until the wire can be clipped by an orthodontist.

Patients with periodontal disease usually must obtain periodontal treatment before getting braces. A deep cleaning is performed, and further treatment may be required before beginning orthodontic treatment. Bone loss due to periodontal disease may lead to tooth loss during treatment.

In some cases, teeth may be loose for a prolonged period of time. One may be able to wiggle one's teeth for a year or two after treatment or longer.

The dental displacement obtained with the orthodontic appliance determines in most cases some degree of root resorption. Only in a few cases is this side effect large enough to be considered real clinical damage to the tooth. In rare cases, the teeth may fall out or have to be extracted due to root resorption.

Pain is common after adjustment and may cause difficulty eating for a time, often several days. During this period, eating soft foods can help avoid additional pressure on teeth.

The metallic look may not be desirable to some people, although transparent varieties are available. However, transparent braces usually do not work as well as metallic ones. Transparent braces can also become undesirably stained or discolored by eating or drinking foods with dye in them.

Treatment time and cost
Typical treatment time is from six months to six years, depending on the severity of the case, location, age, etc., although two years is average. Treatment can be accelerated using novel planning and positioning techniques.

Typical cost of braces is about $5,000 in the US, but can be much lower in other countries. In India, the cost is usually around $600 to $1,000. In Commonwealth of Independent countries for example, the cost is $200 to $500 per jaw.

In some European countries, e.g. Sweden, orthodontic treatment is available without charge to patients under 16 (or for treatment to start at 16, such as Ireland), as benefits for orthodontic treatment are provided under government-run health care systems.

Sometimes braces are required more than once if the retainer fails to keep teeth in place.

Types of braces
Modern orthodontists can offer many types and varieties of braces:
 * Traditional braces are stainless steel, sometimes in combination with nickel titanium, and are the most widely used. Many stainless steel brackets are offered by various orthodontic supply companies. These include coventional braces that require ties and newer self-tying (or self-ligating) brackets, like Time brackets by American Orthodontics, SmartClip™ Brackets by 3M Unitek, SPEED, or Damon brackets. Self ligating brackets, in some conditions, determine a reduction of  friction between the wire and the slot of the bracket.
 * Ceramic braces offer a less visible alternative. They blend in more with the natural color of the tooth and are arguably more visually appealing. Some ceramic brackets are not as strong as metal and may require longer treatment time. Some ceramic brackets are also slightly larger than metal ones and may be more difficult to adapt to.
 * Gold-plated stainless steel braces are for people allergic to nickel (a component of stainless steel), but may be chosen because they blend better with teeth, and some people simply prefer the look of gold over the traditional silver-colored braces.
 * Lingual braces are fitted behind the teeth, and are not visible with casual interaction. Lingual braces can be more difficult to adjust to, since they can hinder tongue movement.
 * Progressive clear retainers, marketed under the tradename InvisAlign, may be used to gradually move teeth into their final position. These have the same effect as braces but can be removed easily for eating, etc.
 * A new concept under development are braces using so-called smart brackets. The smart bracket concept consists of a bracket containing a microchip capable of measuring the forces applied to the bracket/tooth interface. The goal of this successfully demonstrated concept is to significantly reduce the duration of orthodontic therapy and to set the applied forces in non-harmful, optimal ranges.