Dentistry

INTRODUCTION

Dentistry Picture

Dentistry, a health profession concerned with the prevention, diagnosis, and treatment of disorders of the teeth and adjacent tissues of the head, neck, and mouth. A dentist is a person possessing the education, experience, and legal qualifications required to practise dentistry or any of its phases. The practice of dentistry includes cleaning, filling, and extracting teeth, treating diseased gum tissues, correcting irregularities in tooth alignment, performing surgical operations on the mouth or jaw, and constructing and fitting artificial teeth or dentures.

Dentistry Photo

Disorders in the mouth may cause diseases of other parts of the body; conversely, the teeth and their supporting structures are affected by abnormal conditions in distant parts of the body. Because dental structures generally cannot repair themselves, care of the mouth represents a unique health problem for which dentistry uses its own procedures and techniques, as well as those of medicine, in order to prevent local complications as well as ill effects throughout the body.

Dentistry

Most dentists are general practitioners in all phases of dentistry. Periodic examinations, including the use of X-rays and special instruments and tests, are required in order to detect disorders at an early stage. Encrustations of calculus (tartar), which consists of mineralized bacterial plaque, products of bacterial metabolism, salivary mucus, and food residue, should be removed from the teeth at least once a year. Cavities in the teeth are filled with any of various appropriate materials. Irregularities of alignment are corrected. Teeth badly broken down may be rebuilt, or the dental pulp of infected teeth may require removal. Teeth incapable of being restored must be extracted, and missing teeth need to be replaced by artificial ones.

Teeth with Dental Caries

Dental Caries

A view of the inside of the mouth showing dental caries, or cavities, appearing as dark areas on the front teeth. The term dental caries refers to the destruction, or necrosis, of teeth usually by bacterial action. Cavities have been filled on the rear teeth to prevent further tooth damage.


SPECIALITIES

Dentistry can be subdivided into eight specialized fields, although the general practitioner may undertake as many of them as his or her interest and capabilities permit.

A. Oral Surgery

Oral Surgery

Oral surgery deals with the diagnosis and surgical treatment of any disease, injury, malformation, or deficiency of the jaws or associated structures. An important aspect of oral surgery is the removal of teeth, which may be complicated by their location, peculiar formation, or attachment to the jawbone. Teeth that are embedded in the jawbone or soft tissue are said to be impacted. In such cases the surrounding bone or tissue may have to be removed in order to reach the tooth. Oral surgery also includes the removal of cysts and growths in the jaws and mouth, the setting of fractures of the jaws, and operations for the correction of cleft palate and harelip, both of which are forms of birth abnormalities.

Dental Surgery

Impacted Tooth

Impacted Tooth

An impacted tooth, such as the one shown in the upper left corner of this X-ray, is a tooth embedded in the jawbone or the soft tissue of the jaw. The removal of impacted teeth is a common procedure in oral surgery, a branch of dentistry that deals with the surgery and reconstruction of the teeth, gums, and jawbone.

B. Orthodontics

Orthodontics

Orthodontics has as its function the regulation of the position of the teeth in the dental arch. It deals with the detection, study, prevention, and correction of the condition known as malocclusion, which involves irregularities in tooth position and jaw relationships, and which can lead to deformities of the jaws and face. Malocclusion may be hereditary or may be an acquired defect caused by faulty habits or early loss of teeth as a result of decay. By applying special devices and appliances to the teeth, sometimes in combination with surgery, a proper occlusion of the teeth can be effected by the orthodontist.

C. Prosthodontics

Prosthodontics

Prosthodontics deals with the various methods of providing artificial substitutes, or dentures, for missing teeth, the replacement of which ensures the even distribution of the forces involved in chewing and thus prevents the loss of other teeth as a result of undue stress. The nature of the restoration depends on the health of the remaining teeth and supporting structures. If feasible, a fixed bridge is used to replace missing teeth. This type of replacement is accomplished by constructing crowns, which cover all or a large part of the adjacent teeth, and then by attaching the artificial teeth to the crowns. A fixed bridge made of gold covered with porcelain or acrylic (a plastic material) is lifelike and cannot be readily removed. If sufficient adjacent teeth do not remain to support a fixed bridge, then a removable partial denture is constructed. This type of prosthetic device is usually secured by clasps, which embrace several of the remaining teeth. The clasps may be made of gold or of a cobalt-steel alloy. This type of appliance must be removed frequently to be cleaned. When all teeth must be replaced, a full denture is made. The retention of this type of denture depends on the firmness of the underlying tissues and the adhesion provided by the saliva in the mouth. Full dentures are usually made of acrylic, reinforced occasionally with metal. Prosthodontists also replace portions of the oral cavity that are missing because of malformations or deficiencies.


Another surgical approach to tooth replacement is the dental implant, which can take a number of forms. Screws may be drilled into the jawbone to serve as anchors for caps, a metal blade may be fixed to the bone and teeth can then be cemented to posts on the blade, or a metal frame may be placed below the gum for tooth support when the bone itself is too fragile. A full set of teeth may be implanted by such means. These expensive processes are not favoured by all dentists, but a growing number of patients are choosing implant surgery.

Dentures

Dentures

Full dentures, prosthetic devices used by dentists to serve as replacements for large numbers of missing teeth, are custom-designed to fit each patient. Dentures are constructed from acrylics and are often reinforced with various metal alloys. They are designed to be removable for cleaning and are kept in the mouth through the use of special oral adhesives.

Tooth Repair

Tooth Repair

A variety of methods are used to repair or replace damaged teeth. If part of the tooth is salvagable

• The dentist may remove the damaged portion with a drill
• Then cement a tooth-like cap, or crown, to the remaining portion of the tooth
• If a damaged tooth is beyond repair, it must be extracted
• and replaced with artificial teeth made of metal, porcelain, or plastic. In a bridge, artificial teeth are fixed in place with a crown cemented to the two neighbouring teeth.
• Implants are metal posts surgically implanted in the jawbone, then capped with artificial teeth .

D. Periodontics

Periodontics

Periodontics is concerned with the study and treatment of the supporting structures and tissues surrounding the teeth. The gums, or gingivae, and the underlying bone are subject to many disorders. Calculus encrustations on the teeth, which form over and under the gum, act as an irritant to the underlying tissues. Food accumulating on the neck of the tooth and irregularities such as cavities, malocclusions, or poorly constructed dental appliances also act as irritants. In addition, imbalance of tooth-cusp relationships may force food particles into the gums. When subjected to irritants, such soft tissues as the gingivae become inflamed, and eventually the adjacent bone may be destroyed. Thus, the tooth ultimately becomes loosened because of the loss of bone around its roots.

Inflammation of the gum is called gingivitis, and infections destroying the gum tissue and bone are called periodontitis. Although gum diseases are the greatest single cause of tooth loss after the age of 21, these conditions also occur in children. Another common gum disorder is necrotizing ulcerative gingivitis, known commonly as trench mouth, or Vincent's infection. When untreated, it destroys the interdental papillae (small protuberances) of the teeth and causes loosening of the teeth; it is often associated with widespread infection. Other common diseases of the mouth include thrush and viral infections.

Periodontal treatment includes the removal of calculus with curettes (tools for scraping) and scalers, and the application of medicines to the soft tissues. Loosened teeth may be splinted together for support during the healing process; infected or necrotized gum tissue is excised; and malocclusions are corrected by grinding the teeth to obtain effective occlusal relationships.

Periodontitis

Periodontitis

In a healthy tooth (A) the gum lies right up against the tooth. With inadequate dental care bacterial deposits build up into a film described as plaque (B), which, through mineralization, develops into tartar. The gum becomes infected and begins to recede. If this process continues, the neck of the tooth becomes exposed (C). Eventually it results in disintegration of the jaw bone: the tooth loosens its hold and falls out.

E. Endodontics

Endodontics

Endodontics deals with surgical and therapeutic procedures involved in the protection of the pulp (commonly known as the nerve) or its removal from the pulp cavity when diseased or injured, and root canals. Bleaching of front teeth is also included in this speciality.

F. Paediatric Dentistry

Paediatric Dentistry

The field of paediatric dentistry (formerly called paedodontics) deals with the general practice of dentistry for patients under 20 years of age and, in general, patients possessing wholly deciduous or mixed dentition—that is, both primary and permanent teeth. The practice may include the use of such appliances as space maintainers and bite plates for the prevention or treatment of malocclusion. Another paediatric procedure sometimes practised is to apply a sealant to protect the chewing surfaces of a child's molars from bacteria. The teeth are first treated with a solution to make them more porous to the plastic resin that is then applied, making them more resistant to decay.

G. Oral Pathology

Oral Pathology

Oral Pathology is concerned with the nature of oral disease, its causes, processes, and effects, together with the alterations of function and structure. Diagnosis of oral disease is accomplished through the use of laboratory tests of sputum, blood, and other body fluids, as well as through the microscopic examination of tissues. The oral pathologist, who usually works in the laboratory of a hospital, serves the patient only indirectly through consultation with the general practitioner.

H. Public-Health Dentistry

Public-Health Dentistry

Public-health dentistry is concerned with the prevention and control of dental diseases and the promotion of dental health through organized community efforts. It relates to three basic career areas in dentistry: dental public health, research, and clinical dentistry. Each of these career areas may involve practice, teaching, or administration.

HISTORY

One of the first records of dental disease is found on Sumerian clay tablets (5000 bc) inscribed in cuneiform; it states that toothache is caused by small gnawing worms within the tooth. The development of dentistry as an independent speciality had its beginnings in ancient Egypt; tombstones erected in about 3000 bc bear inscriptions indicating that tooth doctors were numbered among the medical specialists. No evidence indicates that they performed restorative dentistry, but the Etruscans were replacing missing teeth as early as 700 bc.
In about 400 bc, the Greek doctor Hippocrates described the function and sequence of eruption of the teeth. In his studies of natural history in the 4th century bc, the Greek philosopher Aristotle investigated the comparative anatomy of the teeth. During the 1st century ad the Roman encyclopedist Aulus Cornelius Celsus discussed dental diseases and suggested that before extraction a carious (decaying) tooth should be filled with lint to prevent it from breaking. The Greek doctor Galen, who settled in Rome during the 2nd century, operated successfully on harelip and advocated the use of a file in removing decayed portions of a tooth. He was the first writer to discuss the dental nerves.

In the 16th century the first specialized works devoted entirely to dentistry appeared. The greatest contribution in the early history of dental anatomy was Libellus de Dentibus (Pamphlet on Teeth, 1563), written by the Italian anatomist Bartolomeo Eustachio. French dentist Pierre Fauchard is known as the founder of modern dentistry. With his publication of The Surgeon Dentist (1728; translation of 2nd ed., 1946), dentistry was established as a separate scientific branch of medicine. In 1771 the British surgeon John Hunter published his Natural History of Human Teeth, which forms the foundation of all modern texts on the anatomy of the jaws and teeth.

Organized dentistry began in 1840 with the founding of the first dental school in the world, the Baltimore College of Dental Surgery in Baltimore, United States, and the establishment of the American Society of Dental Surgery. In 1935 polymerized acrylic resin was introduced as a base for artificial teeth. Later developments include: the use of diamond and carbide cutters for the preparation of cavities and surfaces; the use of water-cooled drills to reduce heat and pain; radioisotope tracers to study tissues; the development of stronger and lighter materials for dentures, fillings, and cements; and experiments to anchor plastic teeth in jawbones by use of sterile pins.

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