Introduction to Orthodontics
Gowri Sankar, DDS • Viswapurna Senguttuvan, DDS
Dr. Gowri Sankar, MDS*
Dr. Viswapurna Senguttuvan, MDS**
Orthodontics is the branch of dentistry concerned with facial growth, with development of the dentition and occlusion, and with the diagnosis, prevention, interception, and treatment of occlusal anomalies and other abnormalities of the dentofacial region. The term “orthodontia” was apparently used first by Le Foulon in 1839. The name of the specialty “orthodontics” is derived from Greek words “ortho”, meaning right or correct or straight, and “odontos”, meaning tooth, and “ics” meaning science. This brief introduction will seek to familiarize the reader with the history and uses of orthodontics. It will also cover the motives behind orthodontic work, and detail the acute differences between the different branches within the field.
In 1911, Noyes defined orthodontics as “the study of the relation of the teeth to the development of the face, and the correction of arrested and perverted development.”This definition was further modified when in 1922, the British Society for the Study of Orthodontics defined the specialty as “Orthodontics includes the study of the growth and development of the jaws and face particularly, and the body generally as influencing the position of the teeth; the study of action and reaction of internal and external influences on the development, and the prevention and correction of arrested and perverted development.”
Dentofacial Orthopedics (Orthodontics now) has been formally defined by the American Association of Orthodontists as “the area of dentistry concerned with the supervision, guidance, and correction of the growing an mature dentofacial structures, including those conditions that require movement of teeth or correction of malrelationships and malformations of related structures by the adjustment of the relationships between and among teeth and facial bones by the application of forces and/or the stimulation and redirection of the functional forces within the craniofacial complex.”
Well-aligned teeth contribute to the overall oral health of the individual. They also influence the psychological wellbeing of the person. Proper dentition and occlusion are important factors for aesthetics, form, and function. Protruding, irregular, or maloccluded teeth can cause three types of problems for the patient:
- Psychosocial problems because of facial appearance;
- Problems with oral function, including difficulties in jaw movement (muscle incoordination or pain), temporomandibular joint dysfunction (TMD), and problems with mastication, swallowing or speech; and
- Greater susceptibility to trauma, periodontal disease, or tooth decay.
A number of studies in recent years have confirmed that severe malocclusion is likely to be a social handicap. Well-aligned teeth and a pleasing smile carry positive status at all social levels, whereas irregular or protruding teeth carry negative status. It is accepted that dentofacial anomalies and severe malocclusion do have negative effects on the psychological well-being and self-esteem of the individual. Research has shown that an unattractive dentofacial appearance does have a negative effect on the expectations of teachers and employers. It seems clear that the major reason people seek orthodontic treatment is to minimize psychological problems related to their dental and facial appearance. These problems are not “just cosmetic”, but also functional in nature.
A severe malocclusion may compromise all aspects of oral function. It seems reasonable that poor dental occlusion would be a handicap to function.
Patients with anterior open bites and those with markedly increased or reverse overjets often complain of difficulty with eating, particularly when incising food.
If a patient cannot attain contact between the incisors anteriorly, this may contribute to the production of a lisp (interdental stigmatism).
Severe malocclusion may make adaptive alterations in swallowing necessary. For instance, every one of us uses as many chewing strokes as it takes to reduce a food bolus to a consistency that is satisfactory for swallowing. Thus, if chewing is less efficient in the presence of malocclusion, either the affected individual uses more effort to chew or settles for less well-masticated food before swallowing it.
Temporomandibular Joint Dysfunction Syndrome
The relationship of malocclusion and adaptive function to TMD, manifested as pain in and around the TM joint, is well established. The pain may result from pathologic changes within the joint, but more often is caused by muscle fatigue and spasm.
Unerupted impacted teeth, for example maxillary canines, may cause resorption of the roots of adjacent teeth. Dentigerous cyst formations can occur around unerupted third molars or canine teeth. Supernumerary teeth may also give rise to problems, most importantly where their presence prevents normal eruption of an associated permanent tooth or teeth.
Relationship to Injury and Dental Disease
Malalignment may reduce the potential for natural tooth cleansing and increase the risk of decay in susceptible children with a poor diet.
Certain occlusal anomalies may prejudice periodontal support. Crowding may lead to one or more teeth being squeezed buccally or lingually out of their investing bone, resulting in a reduction of periodontal support. This may also occur in a Class III malocclusion where the mandibular incisors in crossbite are pushed labially, leading to gingival recession. Traumatic overbites can also lead to increased loss of periodontal support and, therefore, are another indication for orthodontic intervention.
Trauma to the Anterior Teeth
The risk of trauma to the maxillary incisors increases with the amount of the overjet. Children with overjets in excess of 9 mm were twice as likely to experience trauma. Boys and patients with incompetent lips appear to be more at risk; however, the prevalence of trauma reduces with age, with the peak incidence occurring around 10 years.
Extreme overbite, so that the mandibular incisors contact the palate, can cause significant tissue damage, leading to loss of the maxillary incisors. In a few patients, extreme wear of incisors also occurs with excessive overbite.
In summary, there are a number of dental traits that appear to have an adverse effect upon the longevity of the dentition, indicating that their correction would benefit long-term dental health. These include the following:
- Increased overjet;
- Increased traumatic overbites, anterior crossbites (causing a decrease in labial periodontal support of affected lower incisors);
- Unerupted impacted teeth (where there is a danger of pathology); and
- Crossbites associated with mandibular displacement.
Aims of Orthodontic Treatment
Treatment should not only satisfy the patient’s aesthetic desires, but also satisfy certain functional and physiologic requirements. Jackson summarized the objectives of orthodontic treatment, known as “Jackson’s triad”:
- Functional efficiency
- Structural balance
- Aesthetic harmony
Form and function are interrelated. Any deviation from normal occlusion (ie, malocclusion) may adversely affect normal functions carried out by the oral cavity. One of the main aims of the orthodontist is to improve the functional efficiency of the stomatognathic system along with improving the aesthetics.
Orthodontic treatment affects the entire stomatognathic system, which includes not only the teeth (including the periodontal ligament) but also the surrounding soft tissue envelope (including musculature) and the associated skeletal structures (basal bone and TMJ). The treatment should maintain a balance between these structures, and the correction of one should not be detrimental to the health of the other.
Most individuals seek orthodontic treatment to improve the appearance of the smile and face. The orthodontic treatment should increase the overall aesthetic appeal of the individual.
The Scope of Orthodontic Treatment
Orthodontic treatment can bring about changes in the dentition and the structures around the dentition, such as the basal skeletal bone as well as the enveloping soft tissue components.
Orthodontic Change (Alteration in Tooth Position)
Most malocclusions involve only the dental structures, and this can be effectively treated by moving teeth so as to bring them into ideal or at least acceptable positions. Orthodontic treatment is based on the fact that teeth can be moved through the bone to the predetermined ideal locations by applying appropriate forces above certain threshold levels. How efficiently this can be undertaken and to what extent depends upon the nature of the malocclusion and the capability of the individual clinician.
Orthopedic Change(Alteration in Skeletal Pattern)
Malocclusion may result from skeletal disharmony or disproportions between the basal jaw bones (ie, maxilla and mandible). This deviation from the skeletal components is genetically determined or influenced by environmental conditions. Depending upon the age and growth potential of the patient, it is possible to move entire jaws into more favorable positions. This is achieved by using functional appliances or orthopedic forces in growing children that are capable of restraining, promoting, or redirecting skeletal growth so as to normalize the skeletal system. Through orthognathic surgeries, the jaws can be brought into favorable positions in adult patients where active growth has ceased. The skeletal structures can be altered by an orthodontist along with the other team members in all three planes, i.e., vertical, transverse, and sagittal directions.
Altering the Soft Tissue Envelope
The form and function of the surrounding soft tissue envelop of the teeth and the oral cavity have a definite impact on the growth and development of the oral and facial structures. It is possible to bring about favorable changes in the soft tissue pattern by orthodontic treatment. The orthodontist can help retain or restrain the soft tissue and/or bring about a change in them by altering the position of the teeth or jaws.
Branches of Orthodontics
Services offered by the orthodontist can be divided into four categories based on the nature and time of intervention:
- Preventive orthodontics
- Interceptive orthodontics
- Corrective orthodontics
- Surgical orthodontics
Preventive orthodontics, as the name implies, is the action taken to preserve the integrity of what appears to be the normal occlusion at a specific time. Preventive orthodontics includes procedures undertaken prior to the onset of a malocclusion in anticipation of a developing malocclusion. It is also called a primary prevention.
It is the phase of the science and art of orthodontics employed to recognize and eliminate potential irregularities and malpositions in the developing denotfacial complex. Interceptive orthodontics includes procedures that are undertaken at an early stage of a malocclusion to eliminate or reduce the severity of the same. This includes secondary preventive measures. This stage differs from the preventive orthodontics in that here malocclusion has already set in. By undertaking appropriate interceptive procedures, it is possible to prevent establishment of a full-fledged malocclusion that may require long-term orthodontic treatment at a later age. Certain procedures under the preventive and interceptive orthodontic field may overlap.
These are the orthodontic procedures undertaken to correct a fully established malocclusion. Corrective orthodontics recognizes the existence of a malocclusion and the need for employing certain technical procedures to reduce or eliminate the problem and the attendant sequelae. The procedures employed in correction may be mechanical, functional, or surgical.
These are surgical procedures that are undertaken in conjunction with or as an adjunct to orthodontic treatment.
Orthodontics is a very specialized and important sect of dentistry. Orthodontics can help people improve their oral function (mastication, speech, swallowing) as well as their psychological well being (self-esteem). Orthodontics can help patients to achieve normal dentition, repair trauma, and increase their overall quality of life. Services by orthodontists can range from preventive procedures, to interceptive, corrective, and surgical procedures, each of which have a unique aim and time of intervention.
*Professor, Department of Orthodontics, Narayana Dental College, Nellore Andhra Pradesh, India.
**Private Practice, Salem, India; Muscat, Oman; Victoria, Seychelles Islands.
- Graber TM. Orthodontics: Principles and Practice, ed. 3, WB Saunders, 1988.
- Asbell MB. A brief history of orthodontics. Am J Orthod Denotofac Orthop 1990;98(2):176-183.
- Newman GV. Epoxy adhesives for orthodontic attachments. American Journal of Orthodontics, 1965;51(12):901-912.