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Orthodontics

Definition

Orthodontics is a specialized branch of dentistry that diagnoses, prevents, and treats dental and facial irregularities called malocclusions. Orthodontics includes dentofacial orthopedics, which is used to correct problems involving the growth of the jaw.

Purpose

Humans have attempted to straighten teeth for thousands of years before orthodontics became a dental specialty in 1900. Although orthodontic treatment often improves facial appearance and occasionally is performed for solely cosmetic reasons, it is used primarily to correct health problems and to ensure the proper functioning of the mouth. Properly aligned teeth, which close together correctly, simplify oral hygiene and enable children to chew their food efficiently. Orthodontic treatment provides the following:

Few children have perfectly symmetrical teeth and a perfect bite. In an ideal bite, the following are characteristics:

Types of malocclusions include the following:

Most malocclusions are caused by hereditary factors that affect the contours of the face and the size of the teeth and jaw. The most common cause of malocclusion is a disproportion in size between the jaw and teeth or between the upper and lower jaws. A child who inherits a mother's small jaw and a father's large teeth may have teeth that are too big for the jaw, causing overcrowding. Specific inherited malocclusions include:

Malocclusions can be acquired through the following:

Occasionally children have mild, temporary symptoms of malocclusion resulting from a growth spurt. However, symptoms of malocclusion usually develop gradually beginning at the age of six. Symptoms may include the following:

Although orthodontic treatment can be performed at any age, children are easier, faster, and less expensive to treat than adults. Most often orthodontic treatment is used on older children and adolescents whose teeth are still developing. However some types of problems are corrected more readily before all of the permanent teeth have erupted and facial growth is complete. If a child's permanent lower incisors erupt behind each other, braces may be required at a young age. Crossbites are usually treated early because they can interfere with biting and chewing. Early treatment also is used when thumb- or finger-sucking has affected teeth positioning.

Early orthodontic intervention can provide the following:

Other advantages of early orthodontic treatment include the following:

Minor misalignment or crowding may not require treatment. However untreated malocclusions can cause the following:

Untreated malocclusions often worsen with time. TMJ problems can cause chronic headaches or pain in the face and neck. A deep overbite can cause significant pain and bone damage and may contribute to excessive wear on the incisors.

Description

Alignment problems usually become apparent as the permanent teeth begin erupting at about age six. Dentists monitor the development of a child's permanent teeth and refer the child to an orthodontist if a problem is suspected. The American Association of Orthodontists recommends that all children be screened by an orthodontist by the age of seven.

Once a child's lower baby incisors have erupted, an orthodontist can measure the child's jaw and tooth size, project their growth rate, and possibly predict whether the child will have orthodontic problems with their permanent teeth. The orthodontist may be able to perform preventative or interceptive orthodontics that can reduce or eliminate the need for braces later.

In a procedure called selective serial extraction, the orthodontist removes one or more baby or permanent teeth. Doing so creates space for the permanent teeth, especially unerupted canine teeth that might become impacted or erupt in the wrong position. After the removal or loss of a tooth, braces or another orthodontic appliance may be used to prevent the remaining teeth from moving into the empty space. If a baby molar—that acts as a space-holder for later permanent teeth—is lost, a fixed orthodontic wire is inserted between the teeth to keep the space available.

The orthodontist compiles pretreatment records that are used for diagnosis, determining the course of treatment, and measuring the progress of treatment. These records may include:

Based on the diagnosis the orthodontist develops a custom treatment plan and designs the appropriate corrective appliances that will gradually straighten or move the teeth. Severe overcrowding may necessitate the extraction of permanent teeth, usually the premolars, to create space prior to using braces to move teeth.

By applying constant gentle pressure in a specific direction, braces can slowly move teeth through the supporting bone to a new position. Springs and wires put pressure on teeth in order to straighten them. The pressure causes bone in the jaw to dissolve in front of the moving tooth as new bone grows behind the tooth. Braces and other appliances may be removable or fixed and are made of clear or colored metal, ceramic, or plastic. Removable appliances are often plastic plates that fit into the roof of the mouth and clip onto a tooth.

Fixed braces exert more pressure than removable braces and can achieve more complex movements. They consist of wires and springs that are held in place by small brackets glued to the outside surfaces of the incisors and sometimes the premolars. Lingual braces have brackets bonded to the back of the teeth. Bands encircling the molars also can be used for attachments. The wires, springs, and other devices attached to the brackets or bands put pressure on the teeth, gradually shifting them into new positions. The nickel-titanium wires are very light, and some are heat-activated. These are very flexible at room temperature and actively begin to move the teeth as they warm to body temperature. Elastic bands sometimes connect the upper and lower teeth to create tension.

Appliances used to direct jaw growth and development in growing children and adolescents include:

Headgear and Herbst appliances can significantly reduce protrusion of the four top incisors and enable the growing lower jaw to catch up with the upper jaw, eliminating swallowing problems.

Children with braces. (Photograph by Robert J. Huffman/Field Mark Publications.)
Children with braces.
(Photograph by Robert J. Huffman/Field Mark Publications.)

Orthodontic treatment usually continues until the desired outcome is reached. Active orthodontic treatment lasts an average of two years, with a range of one to three years. Some children respond to treatment faster than others and interceptive or early treatments may continue for only a few months. Appliances are adjusted periodically during treatment. Factors affecting the duration of treatment include:

Orthodontic appliances trap food, bacteria, and plaque, leading to tooth decay . Extra brushing with specially shaped and/or electric toothbrush and fluoride toothpaste is required around the areas where the braces or appliances attach to the teeth. Both the tops and bottoms of braces must be brushed and irrigated with a water jet directed from the top down and the bottom up. If possible, teeth should be flossed. A fluoride mouthwash may be recommended. Removable appliances should be brushed every time the teeth are brushed. Regular dental check-ups and cleanings must be continued.

Children with braces should eat raw fruits and vegetables and avoid soft, processed, and refined foods that attract bacteria, as well as hard or sticky foods, including gum, caramels, peanuts, ice chips, and popcorn. Chewing on hard items, such as fingernails or pencils, can damage braces. Children with braces should wear a protective mouth guard while playing contact sports .

After braces are removed the teeth must be stabilized in their new positions. This phase of treatment commonly takes two to three years. Occasionally it continues indefinitely. Types of retainers used for stabilization include:

Risks

Braces may cause discomfort when they are first installed or adjusted during treatment. For the first three to five days teeth may hurt during biting. Lips, cheeks, and tongue may be irritated for one to two weeks before they toughen and adapt to the braces. Some appliances may interfere with speech for the first day or two. Damaged appliances can extend the length of treatment and negatively affect the outcome.

Food particles and plaque deposits around orthodontic appliances can cause demineralization of the tooth enamel, leading to cavities and permanent whitish scars on the teeth.

KEY TERMS

Active treatment stage —The period during which orthodontic appliances or braces are used.

Bicuspid —Premolar; the two-cupped tooth between the first molar and the cuspid.

Canines —The two sharp teeth located next to the front incisor teeth in mammals that are used to grip and tear. Also called cuspids.

Crossbite —The condition in which the upper teeth bite inside the lower teeth.

Crown —The natural part of the tooth covered by enamel. A restorative crown is a protective shell that fits over a tooth.

Deep bite —A closed bite; a deep or excessive overbite in which the lower incisors bite too closely to or into the gum tissue or palate behind the upper teeth.

Eruption —The process of a tooth breaking through the gum tissue to grow into place in the mouth.

Impacted tooth —Any tooth that is prevented from reaching its normal position in the mouth by another tooth, bone, or soft tissue.

Incisors —The eight front teeth.

Interceptive orthodontics —Preventative orthodontics; early, simpler orthodontic treatment.

Malocclusion —The misalignment of opposing teeth in the upper and lower jaws.

Molars —The teeth behind the primary canines or the permanent premolars, with large crowns and broad chewing surfaces for grinding food.

Open bite —A malocclusion in which some teeth do not meet the opposing teeth.

Orthognatic surgery —Surgery to alter the relationships of the teeth and/or supporting bones, usually in conjunction with orthodontic treatment.

Overbite —Protrusion of the upper teeth over the lower teeth.

Plaque —A sticky film of saliva, food particles, and bacteria that attaches to the tooth surface and causes decay.

Retainer —An orthodontic appliance that is worn to stabilize teeth in a new position.

Retention treatment stage —The passive treatment period following orthodontic treatment, when retainers may be used to stabilize the teeth.

Temporomandibular joint (TMJ) —One of a pair of joints that attaches the mandible of the jaw to the temporal bone of the skull. It is a combination of a hinge and a gliding joint.

Maturational change can cause teeth to gradually shift with age—at least until one's early 20s—causing crowding. Nighttime retainers can prevent maturational movement.

Parental concerns

In general the earlier an orthodontic problem is detected, the easier and less expensive it is to correct. Parents can compare their child's dental development with standard charts and pictures.

Children with problems involving the width or length of the jaws should be evaluated no later than age 10 for girls and age 12 for boys. For children receiving orthodontic care, the orthodontist should be notified immediately if an appliance breaks. Indications that children may need an early orthodontic examination include:

Resources

Ireland, Anthony J., and Fraser McDonald. The Orthodontic Patient: Treatment and Biomechanics. New York: Oxford University Press, 2003.

Sutton, Amy L., ed. Dental Care and Oral Health Sourcebook: Basic Consumer Health Info , 2nd ed. Detroit, MI: Omnigraphics, 2003.

Takada, K., and W. R. Proffit. Orthodontics in the 21st Century: Where Are We Now? Where Are We Going? Osaka, Japan: Osaka University Press, 2002.

van der Linden, Frans P. G. M. Orthodontic Concepts and Strategies. Chicago: Quintessence Publishing, 2004.

"Dental Health; New Orthodontic Appliance Designed to Straighten Teeth Without Braces." Medical Devices & Surgical Technology Week (May 16, 2004): 53.

Henrickson, T., and M. Nilner. "Temporomandibular Disorders, Occlusion and Orthodontic Treatment." Journal of Orthodontics 30 (2003): 129–37.

Joffe, L. "Current Products and Practice, Invisalign: Early Experiences." Journal of Orthodontics 30 (2003): 348–52.

American Academy of Pediatric Dentistry. 211 East Chicago Avenue, Suite 700, Chicago, IL 60611–2663. Web site: http://www.aapd.org.

American Association of Orthodontists. 401 N. Lindbergh Blvd., St. Louis, MO 63141–7816. Web site: http://www.braces.org.

American Dental Association. 211 East Chicago Avenue, Chicago, IL 60611–2678. Web site: http://www.ada.org.

"About Orthodontics." American Association of Orthodontists , 2004. Available online at http://www.braces.org/braces/about/faq/faq_concerns.cfm (accessed November 21, 2004).

"Early Orthodontic Care." American Academy of Pediatric Dentistry. Available online at <www.aapd.org/publications/brochures/content/earlyortho.html> (accessed November 21, 2004).

"Facts about Orthodontics." American Association of Orthodontists. Available online at http://www.braces.org/about/faq/faq_background.cfm (accessed November 21, 2004).

"Frequently Asked Questions: Braces and Orthodontics." American Dental Association. Available online at http://www.ada.org/public/topics/braces_faq.asp (accessed November 21, 2004).

Paladin, Pam. "Braced for a Century." American Association of Orthodontists. Available online at http://www.braces.org/history/index.cfm (accessed November 21, 2004).

"Problems to Watch for in Growing Children." American Association of Orthodontists. Available online at <www.braces.org/aaortho/braces/about/problems-to-watch-for.cfm� E; (accessed November 21, 2004).

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