Orthodontia, also called orthodontics and dentofacial orthopedics, is a specialty field of dentistry that deals primarily with malpositioned teeth and the jaws: their diagnosis, prevention and correction. An orthodontist is a specialist who has undergone special training in a dental school or college after they have graduated in dentistry. The field was established by the efforts of pioneering orthodontists such as Edward Angle and Norman William Kingsley.
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Etymology
"Orthodontics" is derived from the Greek orthos ("correct", "straight") and -odont- ("tooth").
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History
The history of orthodontics has been intimately linked with the history of dentistry for more than 2000 years. Dentistry had its origins as a part of medicine. According to the American Association of Orthodontists, archaeologists have discovered mummified ancients with metal bands wrapped around individual teeth. Malocclusion is not a disease, but abnormal alignment of the teeth and the way the upper and lower teeth fit together. The prevalence of malocclusion varies, but using orthodontic treatment indices, which categorize malocclusions in terms of severity, it can be said that nearly 30% of the population present with malocclusions severe enough to benefit from orthodontic treatment.
Orthodontic treatment can focus on dental displacement only, or deal with the control and modification of facial growth. In the latter case it is better defined as "dentofacial orthopedics". In severe malocclusions that can be a part of craniofacial abnormality, management often requires a combination of orthodontics with headgear or reverse pull facemask and / or jaw surgery or orthognathic surgery.
This often requires additional training, in addition to the formal three-year specialty training. For instance, in the United States, orthodontists get at least another year of training in a form of fellowship, the so-called 'Craniofacial Orthodontics', to receive additional training in the orthodontic management of craniofacial anomalies.
Methods
Typically treatment for malocclusion can take around 2 years to complete, with braces being altered slightly every 6 to 8 weeks by the orthodontist. There are multiple methods for adjusting malocclusion, depending on the needs of the individual patient. In growing patients there are more options for treating skeletal discrepancies, either promoting or restricting growth using functional appliances, orthodontic headgear or a reverse pull facemask. Most orthodontic work is started during the early permanent dentition stage before skeletal growth is completed. If skeletal growth has completed, orthognathic surgery can be an option. Extraction of teeth can be required in some cases to aid the orthodontic treatment. Starting the treatment process of overjets and prominent upper teeth in children rather than waiting until the child has reached adolescence has been shown to reduce damage to the lateral and central incisors. However the treatment outcome does not differ.
Functional appliances
When there is a maxillary overjet, or Class II occlusion, functional appliances can be used to correct the occlusion. These may be fixed or removable. Fixed dental braces are wires that are inserted into brackets secured to the teeth on the labial or lingual surface (lingual braces) of teeth. Other classes of functional appliances include removable appliances and over the head appliances, and these functional appliances are used to redirect jaw growth. Post treatment retainers are frequently used to maintain the new position of the dentition.
During fixed orthodontic treatment, metal wires are held in place by elastic bands on orthodontic brackets (braces) on each tooth and inserted into bands around the molars. The wires can be made from stainless steel, nickel-titanium (Ni-Ti) or a more aesthetic ceramic material. Ni-Ti is used as the initial arch wire as it has good flexibility, allowing it to exert the same forces regardless of how much it has been deflected. There is also heat activated Ni-Ti wire which tightens when it is heated to body temperature. The arch wires interact with the brackets to move teeth into the desired positions.
Fixed orthodontic appliances aid tooth movement, and are used when a 3-D movement of the tooth is required in the mouth and multiple tooth movement is necessary. Ceramic fixed appliances can be used which more closely mimic the tooth colour than the metal brackets. Some manufacturers offer self-litigating fixed appliances where the metal wires are held by an integral clip on the bracket themselves. These can be supplied as either metal or ceramic.
The surfaces of the teeth are etched, and brackets are attached to the teeth with an adhesive that is durable enough to withstand the orthodontic forces, but is able to be removed at the end of treatment without damaging the tooth. Currently there is not enough evidence to determine whether self-etch preparations or conventional etchants cause less decalcification around the bonding site and if there is a difference between them in bond failure rate. The bonding material must also adhere to the surface of the tooth, be easy to use and preferably protect the tooth surface against caries (decay) as the orthodontic appliance becomes a trap for plaque. Currently a resin/matrix adhesive which is command light cured is most commonly used. This is similar to composite filling material.
Anchorage for the appliance prevents unwanted movement of teeth and it can come from the headgear worn, the palate, or surgical implants.
For young patients with mild to moderate Angle Class III malocclusions (prognathism), a functional appliance is sufficient for correction. Examples of functional appliances are: facemask, chin-cup, tandem traction bow or headgear. As the malocclusion increases, orthognathic surgery might be required. This treatment comes in three stages. Prior to surgery there is orthodontic treatment to align teeth into their post-surgery occlusion positions. The second stage is surgery such as a mandibular step osteotomy or sagittal/bilateral sagittal split osteotomy depending on whether one or both sides of the mandible are affected. The bone is broken during surgery and is stabilised with titanium plates and screws, or bioresorbable plates to allow for healing to take place. The third stage of treatment is post-surgical orthodontic treatment to move the teeth into their final positions to ensure the best possible occlusion.
A posterior crossbite malocclusion may be corrected using the quad helix appliance or removable appliances during the early mixed dentition stage (eight to 10 years), and more research is required for determining whether any intervention provides greater results than any other for later stages of dentition development. These crossbites are when the maxillary teeth or jaw is narrower than the mandibular, and can occur unilaterally or bilaterally. . Treatment involves the expansion of the maxillary arch to restore functional occlusion, which can either be 'fast' at 0.5mm per day or 'slow' at 0.5mm per week. Palatal expansion can be achieved using either fixed or removable appliances. Banded maxillary expansion involves metal bands bonded to individual teeth which are attached to braces, and bonded maxillary expansion is an acrylic splint with a wire framework attached to a screw in the palatal mid-line, which can be turned and opened to expand the maxilla.
Removable functional appliances are useful for simple movements and can aid in altering the angulation of a tooth: retroclining maxillary teeth and proclining mandibular teeth; help with expansion; and overbite reduction.
Headgear works by applying forces externally to the back of the head, moving the molar teeth posteriorly (distalising) to allow space for the anterior teeth and relieving the overcrowding or to help with anchorage problems.
The facemask aims to pull maxillary teeth and jaw forward and downwards to meet the mandible through a balanced force applied to the upper teeth. The mask rests on the forehead and chin of the wearer, and connects to the maxillary teeth with elastic bands.
Some removable appliances have a flat acrylic bite plane to allow full disocclusion between the maxillary and mandibular teeth to aid in movement during treatment. An example of this is the Clark Twin Block. This design has two blocks of acrylic which disocclude the teeth and protrude the mandible. It is used to treat Class II malocclusion.
Vacuum-formed aligners such as Invisalign consist of clear, flexible, plastic trays that move teeth incrementally to reduce mild overcrowding and can improve mild irregularities and spacing. They are not suitable for use in complex orthodontic cases and cannot produce body movement. They are worn full time by the patient apart from when eating and drinking. A large benefit of these types of orthodontic appliance are that they suitable for use when the patient has porcelain veneers: as metal brackets cannot be bonded to the veneer surface.
Adjunctive therapy
Adjunctive surgical and non surgical therapy have been researched as options to help reduce the duration of orthodontic treatment. Surgical intervention such as alveolar decortication, and corticision have been used in conjunction with orthodontic treatment to reduce the time spent in functional appliances, but more research is required into the possible effects of the surgery. Non-surgical therapy involves the use of vibrational forces during treatment, but it has not been shown whether this significantly reduces the treatment time, orincreases the comfort for the patient.
Extensive research has been done proving the effectiveness of functional appliances, but maintaining the results is important once the active treatment phase has completed.
Post treatment
After orthodontic treatment has completed, there is a tendency for teeth to return, or relapse, back to their pre-treatment positions. Over 50% of patients have some reversion to pre-treatment positions within 10 years following treatment. To prevent relapse, the majority of patients will be offered a retainer (orthodontics) once treatment has completed, and will benefit from wearing their retainers. Retainers can be either fixed or removable. Removable retainers will be worn for different periods of time depending on patient need to stabilise the dentition. Fixed retainers are a simple wire fixed to the labial surface of the incisors using dental adhesive and can be specifically useful to prevent rotation in incisors. Other types fixed retainers can include labial or lingual braces, with brackets fixed to the teeth.
Removable retainers can include one known as a Hawley retainer, made with an acrylic base plate and metal wire covering the canine to canine region. Another form of removable retainer is the Essix retainer which is made from vacuum formed polypropylene or polyvinylchloride and can cover all the dentition.
Diagnosis and treatment planning
In diagnosis and treatment planning, the orthodontist must (1) recognize the various characteristics of a malocclusion or dentofacial deformity; (2) define the nature of the problem, including the etiology if possible; (3) design a treatment strategy based on the specific needs and desires of the individual; and (4) present the treatment strategy to the patient in such a way that the patient fully understands the ramifications of his/her decision.
Training
There are several specialty areas in dentistry, but the specialty of orthodontics was the first to be recognized within dentistry. Specifically, the American Dental Association recognized orthodontics as a specialty in the 1950s. Each country has their own system for training and registering orthodontic specialists.
Canada
In Canada, obtaining a dental degree, such as a Doctor of Dental Surgery (DDS) or Doctor of Medical Dentistry (DMD), would be required before being accepted by a school for orthodontic training. Currently, there are 10 schools in the country offering the orthodontic specialty. Candidates should contact the individual school directly to obtain the most recent pre-requisites before entry. The Canadian Dental Association expects orthodontists to complete at least two years of post-doctoral, specialty training in orthodontics in an accredited program, after graduating from their dental degree.
United States
Similar to Canada, there are several colleges and universities in the United States that offer orthodontic programs. Every school has a different enrollment process, but every applicant is required to have graduated with a DDS or DMD from an accredited dental school. Entrance into an accredited orthodontics program is extremely competitive, and begins by passing a national or state licensing exam.
The program generally lasts for two to three years, and by the final year, graduates are to complete the written American Board of Orthodontics (ABO) exam. This exam is also broken down into two components: a written exam and a clinical exam. The written exam is a comprehensive exam that tests for the applicant's knowledge of basic sciences and clinical concepts. The clinical exam, however, consists of a Board Case Oral Examination (BCOE), a Case Report Examination (CRE), and a Case Report Oral Examination (CROE). Once certified, certification must then be renewed every ten years. Orthodontic programs can award the Master of Science degree, Doctor of Science degree, or Doctor of Philosophy degree depending on the school and individual research requirements.
Bangladesh
Dhaka Dental College in Bangladesh is one of the many schools recognized by the Bangladesh Medical and Dental Council (BM&DC) that offer post-graduation orthodontic courses. Before applying to any post-graduation training courses, an applicant must have completed the Bachelor of Dental Surgery (BDS) examination from any dental college. After application, the applicant must take an admissions test held by the specific college. When successful, selected candidates undergo training for six months.
United Kingdom
Throughout the United Kingdom, there are several Orthodontic Specialty Training Registrar posts available. The program is full-time for three years, and upon completion, trainees graduate with a degree at the Masters or Doctorate level. Training may take place within hospital departments that are linked to recognized dental schools. Obtaining a Certificate of Completion of Specialty Training (CCST) allows an orthodontic specialist to be registered under the General Dental Council (GDC). An orthodontic specialist can provide care within a primary care setting, but to work at a hospital as an orthodontic consultant, higher level training is further required as a post-CCST trainee. To work within a university setting, as an academic consultant, completing research toward obtaining a PhD is also required.
Pakistan
In Pakistan to be enrolled as a student or resident in postgraduation orthodontic course approved by Pakistan medical and dental council, the dentist must graduate with a Bachelor of Dental Surgery (BDS) or equivalent degree. Pakistan Medical & Dental Council (PMDC) has a recognized program in orthodontics as Master in Dental Surgery (MDS) orthodontics and FCPS orthodontics as 4 years post graduation degree programs, latter of which is conducted by CPSP Pakistan.
Oral home care techniques
The presence of orthodontic appliances placed on the teeth makes traditional oral home care techniques very challenging to perform. With orthodontic appliance placement, comes a potential increase in plaque accumulation and cariogenic bacteria levels in the mouth. This makes effective cleaning that much more crucial to maintain good oral health.
See also
References
External links
- What is a Board Certified Orthodontist?
Source of article : Wikipedia
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