Dental braces

Dental braces (also known as braces, orthodontic cases, or cases) are devices used in orthodontics that align and straighten teeth and help to position them with regard to a person's bite, while also working to improve dental health. They are often used to correct underbites, as well as malocclusions, overbites, open bites, deep bites, cross bites, crooked teeth, and various other flaws of the teeth and jaw. Braces can be either cosmetic or structural. Dental braces are often used in conjunction with other orthodontic appliances to help widen the palate or jaws and to otherwise assist in shaping the teeth and jaws.

History

Ancient

According to scholars and historians, braces date back to ancient times. Around 400-300 BC, Hippocrates and Aristotle contemplated ways to straighten teeth and fix various dental conditions. Archaeologists have discovered numerous mummified ancient individuals with what appear to be metal bands wrapped around their teeth. Catgut, a type of cord made from the natural fibers of an animal's intestines, performed a similar role to today’s orthodontic wire in closing gaps in the teeth and mouth.^[1] The Etruscans buried their dead with dental appliances in place to maintain space and prevent collapse of the teeth during the afterlife. A Roman tomb was found with a number of teeth bound with gold wire documented as a ligature wire, a small elastic wire that is used to affix the arch wire to the bracket. Roman philosopher and physician Aulus Cornelius Celsus first recorded the treatment of teeth by finger pressure.^[1] Unfortunately, due to lack of evidence, poor preservation of bodies, and primitive technology, little research was carried on dental braces until around the 17th century, although dentistry as a profession was by then making great advancements.

18th century

Portrait of Fauchard from his 1728 edition of "The Surgical Dentist".

Orthodontics truly began developing in the 17th, 18th, and 19th centuries. In 1728, French dentist Pierre Fauchard, who is often credited with inventing modern orthodontics, published a book entitled "The Surgeon Dentist" on methods of straightening teeth. Fauchard, in his practice, used a device called a "Bandeau", a horseshoe-shaped piece of iron that helped expand the arch. In 1754, another French dentist, Louis Bourdet, dentist to the King of France, followed Fauchard's book with “The Dentist’s Art", which also dedicated a chapter to tooth alignment and application. He perfected the "Bandeau" and was the first dentist on record to recommend extraction of the premolar teeth to alleviate crowding and to improve jaw growth.

19th century

Although teeth and palate straightening and/or pulling was used to improve alignment of remaining teeth and had been practiced since early times, orthodontics, as a science of its own, did not really exist until the mid-19th century. Several important dentists helped to advance dental braces with specific instruments and tools that allowed braces to be improved.

In 1819, Delabarre introduced the wire crib, which marked the birth of contemporary orthodontics, and gum elastics were first employed by Maynard in 1843. Tucker was the first to cut rubber bands from rubber tubing in 1850. Dentist, writer, artist, and sculptor Norman William Kingsley in 1858 wrote the first article on orthodontics and in 1880, his book, "Treatise on Oral Deformities", was published. A dentist named J. N. Farrar is credited for writing two volumes entitled, "A Treatise on the Irregularities of the Teeth and Their Corrections" and was the first to suggest the use of mild force at timed intervals to move teeth.

20th century

In the early 20th century, Edward Angle devised the first simple classification system for malocclusions, such as Class I, Class II, and so on. His classification system is still used today as a way for dentists to describe how crooked teeth are, what way teeth are pointing, and how teeth fit together. Angle contributed greatly to the design of orthodontic and dental appliances, making many simplifications. He founded the first school and college of orthodontics, organized the American Society of Orthodontia in 1901 which became the American Association of Orthodontists (AAO) in the 1930s, and founded the first orthodontic journal in 1907. Other innovations in orthodontics in the late 19th and early 20th centuries included the first textbook on orthodontics for children, published by J.J. Guilford in 1889, and the use of rubber elastics, pioneered by Calvin S. Case, along with H. A. Baker.

Process

Before and after orthodontic treatment with removable dental braces^[2]

The application of braces moves the teeth as a result of force and pressure on the teeth. There are traditionally four basic elements that are used: brackets, bonding material, arch wire, and ligature elastic - also called an “O-ring”. The teeth move when the arch wire puts pressure on the brackets and teeth. Sometimes springs or rubber bands are used to put more force in a specific direction.^[3]

Braces have constant pressure which, over time, move teeth into the desired positions. The process loosens the tooth after which new bone grows in to support the tooth in its new position. This is called bone remodeling. Bone remodeling is a biomechanical process responsible for making bones stronger in response to sustained load-bearing activity and weaker in the absence of carrying a load. Bones are made of cells called osteoclasts and osteoblasts. Two different kinds of bone resorption are possible which are called direct resorption, starting from the lining cells of the alveolar bone, and indirect or retrograde resorption, which takes place when the periodontal ligament has become subjected to an excessive amount and duration of compressive stress.^[3][4] Another important factor associated with tooth movement is bone deposition. Bone deposition occurs in the distracted periodontal ligament and without bone deposition, the tooth will loosen and voids will occur distal to the direction of tooth movement.^[5]

When braces put pressure on teeth, the periodontal membrane stretches on one side and is compressed on the other. If this movement is not done slowly then the patient risks losing their teeth. This is why braces are commonly worn for a year or more and adjustments are only made every few weeks. 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, which partly explains the wide range of response to orthodontic treatment.

Types

• Traditional metal wired braces are stainless steel and are sometimes used in combination with titanium. Traditional metal braces are the most common type of braces. These braces have a metal bracket with elastic (rubber band) ties holding the wire onto the metal brackets. The second most common type of braces are self-ligating braces that do not require the need of elastic ties. Instead, the wire goes through the bracket. Often with this type of braces, treatment time is reduced, there is less pain on the teeth, and fewer adjustments are required than with traditional braces.
• "Clear" braces serve as a cosmetic alternative to traditional metal braces by blending in more with the natural colour of the teeth or having a less conspicuous or hidden appearance. Typically, these brackets are made of ceramic^[6] or plastic materials and function in a similar manner to traditional metal brackets. Clear elastic ties and white metal ties are available to be used with these clear braces to help keep the appliances less conspicuous. Alternately, clear braces can be self-ligating, meaning the wire clips into the bracket without the need for ligatures. Clear braces have a higher component of friction and tend to be more brittle than metal braces. This can make removing the appliances at the end of treatment more difficult and time consuming.

"Clear" braces

• Gold-plated stainless steel braces are often employed for patients allergic to nickel (a basic and important component of stainless steel), but may also be chosen because some people simply prefer the look of gold over the traditional silver-coloured braces.
• Lingual braces are a cosmetic alternative in which custom-made braces are bonded to the back of the teeth making them externally invisible.
• Titanium braces resemble stainless steel braces but are lighter and just as strong. People with allergies to the nickel in steel often choose titanium braces, but they are more expensive than stainless steel braces.
• Multi-Loop Edgewise Archwire (MEAW) therapy employs loops in the wire between teeth. This allows for more efficient vertical alignment of teeth and bite adjustment.^[7]

Traditional braces consist of a small bracket that is glued to the front of each tooth and the molars are adjusted with a band that encircles the tooth. An advantage is one can eat and drink while wearing the braces, but a disadvantage is that one must give up certain foods and eating habits while wearing them, such as gum with sugar and potato chips. Another disadvantage is they have to be periodically tightened by an orthodontist, causing increased amounts of discomfort.

• Customized orthodontic treatment systems (an example of which is Suresmile) combine high-technology including 3-D imaging, treatment planning software and a robot to custom bend the wire. Customized systems such as this offer faster treatment times and more efficient results.^[8] Treatment can be more expensive and is not available at all orthodontists.
• Progressive, clear removable aligners (examples of which are Invisalign, Originator, and ClearCorrect) may be used to gradually move teeth into their final positions. Aligners are generally not used for complex orthodontic cases, such as when extractions, jaw surgery, or palate expansion are necessary. These braces are the most recent type of braces. Many orthodontists do not use these braces because they feel they do not produce the best corrective results compared to traditional braces, but opinions vary from person to person. This technique works by only tilting or rotating the teeth (including the roots), whereas traditional braces can parallel shift the whole tooth (including the roots). The braces are hardly noticeable on the teeth and work to gradually move the teeth into their right position without the need for wires or tightening. Like traditional braces, they do require an improvement in the amount of oral hygiene because they have to be removed to eat and one must brush and floss after every meal. Instead of using the traditional method where metal or clear braces were mounted for long periods of time. Each set of aligners is worn for about 2 weeks, and they are removed to eat, drink, brush and floss. As the aligners are replaced every 2 weeks, the teeth are forced to move to fit the new mold. The total treatment time averages 9-15 months and the average number of aligners worn is between 18 and 30.
• For less difficult cases, spring aligners are also an option that can cost much less than braces or Invisalign (one example is NightShiftOrtho) and still align primarily the front six top and bottom teeth.
• Smart brackets are the latest concept under investigation. The smart bracket contains a microchip that measures the forces that act on the bracket and subsequently, the tooth interface . The aim of these braces is to reduce the duration of orthodontic therapy and the related expenses and discomfort to the individual.
• A-braces^[9] are another new concept in dental appliances. In the shape of a capital letter A, A-braces are applied, adjusted, removed and completely controlled by the user. At the ends of the A's arms are angled knobbed bits that the user bites down over. The width between the bits is adjusted by turning the crossbar, housed across the arms, outside the mouth. A user never has to experience pain because the pressure is so easy to control. Though they are not designed or recommended for wearing while sleeping, A-braces may serve as self-adjustable retainers and palate expanders. ▪'partial braces cover only 4 front teeth and the 2 very back teeth. This is later upgraded to metal wire. 10 years is the minimum age to be able to receive this treatment.

Fitting procedure

A patient's teeth are prepared for application of braces.

Orthodontic services may be provided by any licensed dentist trained in orthodontics. In North America most orthodontic treatment is done by orthodontists, dentists in diagnosis and treatment of malocclusions—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 whether 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, molds, and impressions are made. These records are analyzed to determine the problems and proper course of action. The use of digital models is rapidly increasing in the orthodontic industry. Digital treatment starts with the creation of a three-dimensional digital model of the patient's arches. This model is produced by laser-scanning plaster models created using dental impressions. Computer-automated treatment simulation has the ability to automatically separate the gums and teeth from one another and can handle malocclusions well. This software enables clinicians to ensure, in a virtual setting, that the selected treatment will produce the optimal outcome, with minimal user input.^[10]

Typical treatment times vary from six months to two and a half years depending on the complexity and types of problems. Orthognathic surgery may be required in extreme cases. About 2 weeks before the braces are applied, orthodontic spacers may be required to spread apart back teeth in order to create enough space for the bands.

Teeth to be braced will have an adhesive applied to help the cement bond to the surface of the tooth. In most cases the teeth will be banded and then brackets will be added. 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 infeasible.

An archwire will be threaded between the brackets and affixed with elastic or metal ligatures. Ligatures are available in a wide variety of colors, and the patient can choose which color they like. Archwires are bent, shaped, and tightened frequently to achieve the desired results.

Dental braces, with a transparent power chain, removed after completion of treatment.

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.

Brackets with hooks can be placed, or hooks can be created and affixed to the archwire to affix rubber bands to. The placement and configuration of the rubber bands will depend on the course of treatment and the individual patient. Rubber bands are made in different diameters, colors, sizes, and strengths. They are also typically available either colored or clear/opaque.

The fitting process can vary between different types of braces, though there are similarities such as the initial steps of molding the teeth before application. For example, with clear braces, impressions of a patient's teeth are evaluated to create a series of trays, which fit to the patient's mouth almost like a protective mouthpiece. With some forms of braces, the brackets are placed in a special form that are customized to the patient's mouth, drastically reducing the application time.

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 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 would be used to expand the dental arch, and not the palate.

Sometimes children and teenage patients, and occasionally adults, are required to wear a headgear appliance as part of the primary treatment phase to keep certain teeth from moving (for more detail on headgear and facemask appliances see Orthodontic headgear). When braces put pressure on one's teeth, the periodontal membrane stretches on one side and is compressed on the other. This movement needs to be done slowly or otherwise the patient risks losing his or her teeth. This is why braces are worn as long as they are and adjustments are only made every so often.

Braces are typically adjusted every three to six weeks. This helps shift the teeth into the correct position. When they get adjusted, the orthodontist removes the colored or metal ligatures keeping the archwire in place. The archwire is then removed, and may be replaced or modified. When the archwire has been placed back into the mouth, the patient may choose a color for the new elastic ligatures, which are then affixed to the metal brackets. The adjusting process may cause some discomfort to the patient, which is normal.

Post-treatment

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

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.

Retainers

Hawley retainers are the most common type of retainers. This picture shows retainers for the top and bottom of the mouth.

In order to prevent the teeth moving back to their original position, retainers may be worn once the treatment with braces is complete for the patient depending on their specific needs. Retainers help in maintaining and stabilizing the position of teeth long enough to permit reorganization of the supporting structures after active phase of orthodontic therapy. If the patient does not wear the retainer appropriately for the right amount of time, the teeth may move towards their previous position. For regular traditional braces Hawley retainers are used. They are made of metal hooks that surround the teeth and are enclosed by an acrylic plate shaped to fit the patient's palate. For invisalign braces an Essix retainer is used. They are similar to the regular invisalign braces and is a clear plastic tray that is firmly fitted to the teeth that stays in place, and does not have a plate fitted to the palate. There is also a bonded retainer where a wire is permanently bonded to the lingual side of the teeth, usually the lower teeth only. Doctors will sometimes refuse to remove this retainer, and it may require a special orthodontic appointment to have it removed.

Headgear

Headgear needs to be worn between 12–22 hours each day to be effective in correcting the overbite, typically for 12 to 18 months depending on the severity of the overbite, how much it is worn and what growth stage the patient is in. Typically the prescribed daily wear time will be between 14 and 16 hours a day and is frequently used post primary treatment phase to maintain the position of the jaw and arch.

Orthodontic headgear will usually consist of three major components:

Full orthodontic headgear with headcap, fitting straps, facebow and elastics

1. Facebow: first, the facebow (or J-Hooks) is fitted with a metal arch onto headgear tubes attached to the rear upper and lower molars. This facebow then extends out of the mouth and around the patients face. J-Hooks are different in that they hook into the patients mouth and attach directly to the brace (see photo for example of J-Hooks).
2. Head cap: the second component is the headcap, which typically consists of one or a number of straps fitting around the patients head. This is attached with elastic bands or springs to the facebow. Additional straps and attachments are used to ensure comfort and safety (see photo).
3. Attachment: the third and final component – typically consisting of rubber bands, elastics, or springs – joins the facebow or J-Hooks and the headcap together, providing the force to move the upper teeth, jaw backwards.

The headgear application is one of the most useful appliances available to the orthodontist when looking to correct a Class II malocclusion. See more details in the section Orthodontic headgear.

Pre-finisher

The pre-finisher is molded to the patient's teeth by use of extreme pressure to the appliance by the person's jaw. The product is then worn a certain amount of time with the user applying force to the appliance in their mouth for 10 to 15 seconds at a time. The goal of the process is to increase the exercise time in applying the force to the appliance. If a person's teeth are not ready for a proper retainer the orthodontist may prescribe the use of a preformed finishing appliance such as the pre-finisher. This appliance fixes gaps between the teeth, small spaces between the upper and lower jaw, and other minor problems.

Complications and risks

Experiencing some pain following fitting and activation of fixed orthodontic braces is very common and several methods have been suggested to tackle this.^[11][12]

Plaque forms easily when food is retained in and around braces. It is important to maintain proper oral hygiene by brushing thoroughly when wearing braces to prevent tooth decay, decalcification, or unpleasant color changes to the teeth. Interdental brushing may be recommended as an alternative to flossing as the latter may be difficult or unrecommended with braces. Regular use of mouthwash is also recommended.

There is a small chance of allergic reaction to the elastics or to the metal used in braces. In even rarer cases, latex allergy may result in anaphylaxis. 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 mouth guard to prevent breakage and/or mouth injury when playing sports. Certain sticky or hard foods such as taffy, raw carrots, hard pretzels, and toffee should be avoided because they can damage braces. Frequent damage to braces can prolong treatment. Some orthodontists recommend sugar-free chewing gum in the belief that it may expedite treatment and relieve soreness; other orthodontists object to gum chewing because it is sticky and may therefore damage the braces.

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 (e.g. tweezers, clean eraser side of a pencil) 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.^[13][14]

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

Removal of the cemented brackets can also be painful. The cement must be chipped and scraped off which can cause severe pain in patients with sensitive teeth. Often molar bands have been installed for an extended period of time and they may be embedded in the gums at the time of removal.

The metallic look may not be desirable to some people, although transparent or lingual (behind-teeth) varieties are available. According to a survey published in the American Journal of Orthodontics and Dentofacial Orthopedics, dental braces with no visible metal were considered the most attractive. Ceramic braces with thin metal or clear wires were a less desirable option, and braces with metal brackets and metal wires were rated as the least aesthetic combination.^[15]

Changes in the shape of the face, jaw and cheekbones may also occur as a result of wearing braces. Some patients may wish to discuss these potential changes before starting treatment.

See also

References

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