This page provides a glossary of terms that you may encounter while exploring this site. Simply click on the highlighted letters below to jump to the alphabetical listing you require.

A

An abscess is a localized collection of pus in an enclosed area or space, somewhere within the body. Abscesses may occur around the teeth and jaws, and are often associated with an infection. They are commonly divided into ACUTE or CHRONIC abscesses.

An ACUTE abscess is one which is very active and often painful, and which you will want to seek help quickly. It may also be associated with SWELLING and INFLAMMATION.

A CHRONIC abscess may or may not be painful, and is generally a slower process for the abscess to form and to heal. It may also be associated with swelling and inflammation, but is often not so painful as pus finds a route to drain away in the form of a SINUS.

All abscesses should be treated, as they are a sign of PATHOLOGY. Your dentist may recommend all or one of the following: OPEN surgically and DRAIN the abscess, ANTIBIOTIC treatment, ENDODONTIC treatment, PERIODONTAL treatment or ROOT PLANING, other SURGICAL treatment.

You should not try to treat an abscess at home, as you might exacerbate the problem and spread the infection. Seek treatment from a dentist as soon as possible, and do not use hot or warm compresses in the area unless told to, as this may also alter the way which infection spreads.

Abutment

A tooth or root or other device e.g. an IMPLANT, used for support, stabilization or anchorage against lateral or horizontal thrust for either a fixed or removable denture PROSTHESIS.

Acid Etching

Acid etching is the selective dissolution of a surface (usually the tooth enamel) by a dilute acid. In the case of the tooth surface, this causes demineralisation of the enamel leaving a clean and more mechanically retentive surface, thereby improving the bonding to filling materials. The acid used is generally 30% to 50% Phosphoric acid.

Aesthetic / Esthetic dentistry

The treatments, skills, and techniques used to improve appearance of the patients as a whole by adjusting the position form, function, and symmetry of the teeth, jaws and face. Importance is placed especially on colour and form.

Amalgam

Also called SILVER FILLING RESTORATION or ALLOY RESTORATION. Dental amalgam is a mixture or ALLOY of metals, including mercury,silver, copper and zine, which is combined to form a soft and silvery looking paste which hardens on setting. It is the filling materials that used for the restoration of the form and function of teeth.

Dental amalgam has been used extensively for many years in dentistry as the material of choice for fillings. In recent years there has, however, been much debate both within the profession and amongst the general public, about the safety of the material, and more specifically, the safety of the MERCURY used in the mixture. Mercury and mercury vapor are toxic, and may produce acute or chronic poisoning, causing damage mainly to the nervous system. Once combined with other metals, however, mercury alloy becomes SAFE, so the mixing and handling procedures are the most important as far as safety is concerned. There are very strict guidelines in Hong Kong and other countries relating to the handling of mercury in dental practice.

Over the years, amalgam has provided a stable and extremely useful restorative material. There are literally billions of amalgam restorations that have been carried out, and the reports of side effects, symptoms, and reactions to the material are negligible in comparison to the number of teeth treated. There is however, an ever more vocal and well documented lobby against the use of amalgam, and many recorded cases now of patients who appear to have had symptoms which have been attributed to amalgam, and which have been reduced or have disappeared after the removal of amalgam from their teeth. Some countries, most notably in Scandinavia, have either banned the use of amalgam, or are no longer recommending it's use as a filling material of choice, especially in the treatment of children and pregnant women.

Your dentist will advise you on whether or not he still recommends the use of amalgam as a filling material. The improvement in the structure and techniques of other materials in recent years has meant that patient and dentist have more choices in the alternative materials available.

Angle's Classification of Occlusion

To help dentists quickly describe a patient's teeth and the way they come together, certain normal and abnormal situations have been described and classified, and these are used for communication and defining the case. The man who invented this system was an American ORTHODONTIST called Edward Angle.( 1855- 1930 )

Apicoectomy

This procedure may also called ROOT END RESECTION, or ROOT END AMPUTATION, APICOTOMY, or APECTOMY but these terms are more unusual. It is a surgical procedure to remove the tip or end of the root of a tooth lying in the bone of the jaws, through an opening made in the buccal (cheek side) or palatal side of the tooth. At the same time, tissue from around the APEX or end of the root may be removed to control a disease process and to facilitate healing. The procedure is usually associated with ROOT CANAL TREATMENT, either during the procedure, or more often afterwards, if an earlier root canal treatment has not healed satisfactorily. The dentist or surgeon may also carry out a RETROGRADE ROOT FILLING, i.e. a filling placed in the end of the remaining portion of the root to seal the ROOT CANAL at the same time.

You will normally need to have a number of X-RAYS or RADIOGRAPHS associated with this treatment. These are necessary to control and check the success of the procedure. After the surgery, you may notice some swelling around the area, as the wound heals. Your dentist may also wish to give you some ANTIBIOTICS to help the healing and prevent further infection prescribes.

Autoclave

This is a machine which sterilizes instruments using steam at high temperature and pressure. It consists of an hermetically closed container in which the temperature of electrically heated water is allowed to rise to at least 121℃ (250 ℉) at which all living organisms are killed, with a parallel increase in steam pressure to 15 psi. Instruments have to be cleaned thoroughly before sterilization, and also occasionally packed or wrapped in special sterilizing sacks which permit easy penetration of the heat and pressure, used according to the manufacturers' instructions.

B

A bitewing x-ray is a radiograph taken inside the mouth to show the interproximal surfaces of both upper and lower teeth. This x-ray helps to detect decay occurring on the proximal (in between) surfaces of the teeth. The x-ray is held in place in the mouth by biting on a tab on the film.

Bleaching

Bleaching is the act or process of removing stains or colour by chemical means using usually OXIDIZING AGENTS. CORONAL bleaching is the same thing, but carried out within the crowns of PULPLESS teeth, and often in combination with heat or UV light. The material used generally is 30% HYDROGEN PEROXIDE.

HOME BLEACHING KITS are a relatively recent addition to products available to the general public. There are also several types for use in the dental office, and they all work on a similar principal in which the solution or gel of the bleaching agent is held on the teeth for a period of time, which varies from one product to another, in a TRAY or special form which fits over the teeth. There is a risk of damage to the health of the teeth and gums with overuse, and the possibility of the teeth becoming more sensitive is also high. The results of home bleaching are usually of limited duration, so the process may need to be repeated, but many people are satisfied with the results they get. Caution should also be exercised with existing RESTORATIONS in the mouth, which may be damaged or bleached at a different rate to the tooth substance.

Bonding

This means the binding together of various substances like, for instance, gold and porcelain or certain filling materials and the surface of the tooth. In the case where the bonding is between tooth enamel and a filling material, an UNFILLED RESIN is used to assist the mechanical adhesion of the resin material. Bonding may also be carried out with an adhesive substance e.g. glue or cement.

Bracket

A small metal, plastic, or ceramic attachment which serves to fasten an ORTHODONTIC wire to the teeth or to a band around the teeth. There are many different sorts of brackets, and your ORTHODONTIST will select the one suitable for your case.

Bridge

In dental terminology, a bridge is a FIXED PROSTHESIS to replace one or more missing teeth, to restore the function, form or aesthetics of the mouth. It is also known as a FIXED / NON-REMOVABLE PARTIAL DENTURE. Bridges are supported and held in position by attachments to adjacent or remaining teeth.

There are many different types of bridge including FIXED- FIXED, FIXED-MOVEABLE, CANTILEVERED, MARYLAND, ROCHETTE, SPRING CANTILEVERED, ACID-ETCHED, PORCELAIN BONDED, and many others.

Common materials used in their construction include gold and precious metals and their alloys, and porcelain and ceramics.

Teeth generally need to be PREPARED before a bridge can be provided and this will include altering the shape of the teeth, taking IMPRESSIONS and MODELS of the mouth and jaws, and other procedures, so that the bridge can be constructed in the laboratory. RADIOGRAPHS will also be required to check the stability of the remaining teeth and associated structures.

Homecare of bridges should be discussed with your dentist or hygienist, as they may recommend special techniques to keep the bridge clean.

C

Calculus is the hard stone like deposit on teeth formed by plaque that has calcified. Calculus is usually strongly attached to the teeth and must be removed by an instrument. It cannot be brushed off the teeth. Subgingival calculus (below the gums) is usually darker and more adherant to the tooth than the creamy yellow supragingival calculus.

Caries ( dental )/ Tooth Decay

Caries or 'tooth decay' is a disease of the hard structure of the teeth caused by various bacteria in the mouth. For caries to form, the bacteria which are present in PLAQUE need to have sugars from food, and need to be present long enough on the tooth surface to cause DEMINERALIZATION i.e. to cause a reduction in the amount of, for example, Calcium, in the structure of the tooth. Once DEMINERALISATION has taken place, the bacteria can invade the tooth to deeper levels, and eventually a CAVITY or CARIES LESION may occur.

Your dentist will be able to detect the presence of caries by noticing changes in the appearance of your teeth, and by the use of light and X-RAY FILMS or RADIOGRAPHS. This is one of the reasons why dentists recommend regular check-ups, so they can advise you if caries is forming.

When this happens, your dentist may need to do a FILLING or RESTORATION. If caries is left untreated for a longer time, and the bacteria have invaded into the middle i.e. the PULP, of the tooth, you may even need to have a ROOT CANAL TREATMENT or EXTRACTION carried out. Your dentist will advise you on the treatment most appropriate for your tooth.

You can do a lot at home to prevent caries forming in your teeth. Brushing your teeth correctly to remove plaque with a FLUORIDE TOOTHPASTE, and cleaning between the teeth with DENTAL FLOSS or sticks will help to reduce the amount of bacteria (PLAQUE) on your teeth. You can also try to reduce the amount, and the frequency of sugars and sweet things you eat and drink, as this will also help prevent caries. It has been shown that regular brushing, the use of fluorides, and the reduction in quantity and frequency of sugar intake will all help to significantly reduce caries. If you need more information about CARIES and TOOTH DECAY you should ask your DENTIST or HYGIENIST about it.

Cephalometric x-ray

A cephalometric x-ray is a very specific radiograph taken outside the body to show a side view of the head. This x-ray is used to analyze and measure jaw and tooth relations for orthodontics and oral surgery.

Class I Occlusion

This is considered the 'normal' or ideal situation in which the teeth come together. There are various ways of describing and defining the situation, but the most important is by the way the FIRST MOLAR teeth, that is the first 'double' or 'chewing' teeth, meet together when the mouth is closed. In the Class I situation, the lower first molar is slightly in front of the upper first molar by what is known as 'half a unit' when the teeth are held together. This Class I relationship is also reflected often in the position of the front teeth, and the way they overlap one another, slightly forward ( 2-4mm ) and slightly deeper ( also 2-4mm ) than the INCISAL, or biting edge, of the lower ones.

Class II Occlusion

The Class II situation is divided into two sub-divisions, also called DIVISION 1 and DIVISION 2. The class II situation is that where the FIRST MOLAR teeth are in line with one another, or the bottom tooth is even behind the upper first molar tooth when the mouth is closed and the teeth are held together. This situation often occurs when the bottom jaw lies further back than it should, in relation to the upper one. The sub-divisions help describe the common conditions arising in the front teeth when the FIRST MOLAR teeth are in the position described above.

In DIVISION 1 the top teeth come out further forward than they should so that there is an increased gap between them and the lower front teeth. This is a very common situation, and easily recognizable because the front teeth look as if they 'stick out'.

In DIVISION 2 the back teeth are in the class II position, and the front teeth then slope backwards from their normal position to compensate for this. Often the front top teeth overlap the front bottom teeth quite deeply when they come together.

Class III

In this situation, the lower FIRST MOLAR teeth are more forward than they should be in relation to the upper first molar teeth when they come together. They may still bite together when the mouth is closed, but in extreme cases, they don't meet together at all.

The front teeth usually reflect what is happening in the back teeth in the class III situation. The bottom front teeth lie forward from their ideal position, and in some cases, may lie completely in front of the upper front teeth when the mouth is closed together. People who have this type of Class III occlusion usually have it in association with a forwardly positioned or enlarged lower jaw. This type of malocclusion is quite easy to recognize because the person looks like they have a large or prominent chin.

There are also divisions called CLASS 1, 2, AND 3, relating to the positions of a persons jaw bones which are used to classify and describe a situation. These are called the SKELETAL CLASSIFICATIONS, and run usually, but not always, in a similar way to the Angle's classifications. For example, a person with a Class 3 skeletal relationship often has a Class III Angle's relationship too. The definitions of skeletal relationships are more technically defined than the Angle's classification. X-RAY pictures of the patient's skull and jaw bones are normally required for measurement of various normal lengths and angles ( in degrees here! ) and are a little complicated for description here.

Complete denture

A complete denture ( used to be known as FULL denture) is a dental PROSTHESIS replacing all the natural teeth and the associated structures of the maxilla or mandible, except usually the THIRD MOLARS. Complete dentures are usually made of acrylic or metal (cobalt-chrome) and acrylic.

Composite Filling Material.

When used in relation to filling materials the term COMPOSITE usually refers to a substance made up of an acrylic resin filled with inorganic substances such as glass, lithium aluminum silicate, quartz, or tricalcium phosphate. The composite is usually, but not always, applied to the tooth in a plastic i.e. pliable form, and sets, either by itself, or with the use of a blue light. A technique called ACID ETCHING i.e. etched preparation of the tooth surface, is usually used to improve the stability of the filling in the CAVITY. Other techniques, such as COMPUTER GENERATED restoration forms, and INDIRECT COMPOSITE RESTORATIONS i.e. where a filling is first made in a model of the tooth and then fitted in the mouth, are also now being used.

Composite filling materials are used most commonly in the restoration of anterior (front) teeth because they have very good aesthetic properties. They are easy to colour match, and come in many shades and brands.

They are also used now extensively in posterior teeth, i.e. PRE MOLARS and MOLARS, because they are aesthetically more pleasing than amalgam or gold restorations, and also have adequate hardness and strength characteristics.

There are still, however limitations on the use of composite filling materials, especially in posterior teeth, but your dentist will be able to advise you about what sort of material is the best for your particular tooth.

Crossbite

This term is used to define an abnormal situation when the teeth are held together. In a normal mouth, the upper teeth lie just outside the lower teeth when the patient closes her mouth. In a crossbite situation, the lower tooth or teeth lie outside or in the same vertical line as the upper ones. Also called a REVERSE HORIZONTAL OVERLAP.

Crossbites may occur in one or just a few teeth, or in a row of teeth at the side of the mouth. They may indicate an underlying problem such as a discrepancy between the jaw size, or a habit like thumb-sucking which needs treatment.

Crown / Cap

In PROSTHODONTIC or RESTORATIVE terms, a crown or cap is an artificial replacement of part or whole of the ANATOMICAL CROWN of a tooth. It restores ANATOMY, FUNCTION and usually AESTHETICS of the tooth, and is cemented or bonded to the remaining tooth substance.

There are various different types of crown, including BASKET, GOLD, COMPLETE VENEER, FULL, JACKET, PARTIAL, STAINLESS STEEL, THREE- QUARTER, TELESCOPIC, PINNED, WINDOW, TEMPORARY.

Common materials used in crown construction are gold and other precious metals and their alloys, porcelain and ceramics.

Each different type of crown has a different indication and use, and your dentist will advise you on the best type for your case.

A tooth must be PREPARED to have the crown fitted to it, and usually this involves altering the shape of the tooth and making IMPRESSIONS and MODELS of the teeth and mouth so that the crown can be constructed in the laboratory to fit the tooth.

Currettage

Currettage is the removal of diseased gum tissue from the lining of the periodontal pocket. It usually results in less inflammation and subsequent repair and shrinkage of the periodontal pocket.

Currette

A currette is a curved ended hand instrument used to remove plaque and calculus from below the gumline and to remove diseased gingival tissue from a periodontal pocket.

D

See Toothpaste

Diastema

An abnormal space or cleft between two teeth in a dental arch. An ANTERIOR or MEDIAN diastema is one which appears between the two central front teeth. Treatment of diastemata may take various forms, including ORTHODONTIC treatment, surgical treatment of the central FRENUM, and AESTHETIC treatment with CROWNS or VENEERS.

Drill/Handpiece

This is the hand-held device which the dentist uses to remove tooth tissue, for cleaning the teeth, polishing restorations, and so on. The usual choice for the dentist is between one HIGH SPEED drill, which the patients recognize by it's high pitched whining noise, and a drill with a slower speed, which can be used for tasks such as polishing, CARIES removal and so on.

There are many, many different makes, and designs of handpiece. Some of the more common categories of drill include STRAIGHT HANDPIECE, CONTRA-ANGLED, MINIATURE, RECIPROCATING, GIROMATIC, TURBINE and so on.

Drills are driven either by a rotating shaft or compressed air.

E

This means the removal of a tooth from the jaw, usually using instruments called FORCEPS or ELEVATORS. An extraction can also be carried out SURGICALLY, when the dentist needs to make extra incisions or remove some bony tissue to get the tooth to come out. Surgical extractions are carried out when a normal or straight- forward extraction is not possible.

As a patient there are a few guidelines you should follow after having a tooth extracted. You should not rinse your mouth out vigorously for some time (usually 24 hours) afterwards. You should keep your mouth clean, and brush your remaining teeth as normal. You may be given advice on how to stop bleeding from the socket afterwards, (biting on a clean, just-damp cloth or handkerchief) and any other special instructions will be given by your dentist.

F

Floss is composed of soft strands of thread, usually made of silk, nylon or gortex which is used to clean and remove plaque and debris from in between the teeth. It is recommended to floss at least one time per day, and preferably after each meal.

To floss your teeth, you need to pull the floss in between two teeth, then curve the floss around one tooth and slide it underneath the gum. Rub the floss against the tooth up and down a few times. Repeat this procedure on the adjacent tooth.

Food Impaction

Food impaction is the forceful wedging of food into the PERIODONTIUM or embrassive of the teeth by OCCLUSAL, or biting, forces. It often happens in the space between the teeth ( the interproximal area ) and is frequently associated with incomplete filings or very heavily filled teeth. This condition is very bad for the gums, and may lead to severe pain and PERIODONTAL DISEASE which should be treated urgently. In the above mentioned case, it might be necessary to CROWN or CAP the teeth to provide them with adequate support, or build the correct form of the tooth again.

Forceps

Forceps are instruments which have two BLADES and handles, which are used for holding, compressing, or removing something. DENTAL FORCEPS are used for the EXTRACTION of teeth. HAEMOSTATIC FORCEPS are used during surgery to constrict and clamp usually blood vessels. There are many other types as well, and they all have specific uses and applications.

G

Gingivitis is inflammation of the gums characterized by red, swollen and bleeding gums. It is a reversible condition associated with the build up and accumulation of plaque due to improper oral hygiene. Plaque is an irritant to the gums and causes inflammation. Other factors involved in gingivitis are poorly fitting appliances, malaligned teeth, mouthbreathing and overhanging margins of dental restorations.

Gingivitis may lead to a more serious condition known as periodontitis. Please see your dentist to evaluate the health of your gums.

Glass Ionomer

A type of dental cement made up of Calcium Aluminosilicate glass powder and a liquid polyacrylic acid. Although useful in many different situations and restorations, glass ionomer should not be used alone in areas of the mouth where there are high biting forces, for example, the posterior teeth.

Glass ionomers contain FLUORIDE which leaches out of the material and helps prevent the return of CARIES under the filling. They also have a good potential for adhesion with the tooth because the polyacrylic acid reacts with the calcium in the tooth to form a bond. Glass ionomer cements also come in a variety of tooth coloured shades, so that matching is usually quite good.

Gutta Percha

GUTTA PERCHA is a type of material which is made from the sap of trees found in Malaya. It is a very safe substance, and is used in ROOT CANAL treatment to fill up the canals once the PULP has been removed and also as a TEMPORARY FILLING MATERIAL. It is often a pink or grey colour, comes in various shapes and forms, and usually needs heat or pressure to form it into the correct shape.

H

Halitosis, commonly known as bad breath may be due to a number of factors including: poor oral hygiene, decayed teeth and general neglect of the teeth, periodontal disease, deeply furrowed tongue, sinus infection, and tonsillitis. Acidosis, a metabolic condition often caused by diabetes or starvation is another common cause of bad breath.

Diet, especially garlic and onion, can also be a factor in halitosis. Mouthwash does not work well in this situation as the odor is present in your blood stream and is transmitted when breathing.

"Morning mouth" occurs due to the drying of oral tissues especially in those who snore or sleep with their mouth open. The drying allows for increased amount of bacteria to remain in the mouth.

See your dentist to evaluate which of the above factors accounts for your halitosis.

Headgear

This is a harness-like device which is fitted about the head and/or neck in ORTHODONTIC treatment to provide extra support or forces to the APPLIANCE being worn. Because headgear looks a little strange when fitted, the ORTHODONTIST may suggest only wearing it at night or at home; but even if the regime recommended is more than that, the daily wearing time should be strictly adhered to, as this will affect the long term success and the time it takes to finish treatment.

Hygienist

A hygienist is a person trained to perform preventative procedures such as cleaning teeth, applying fluoride, placing sealants, taking x-rays and educating patients on oral health care. Dental hygienists must practice under the supervision of a dentist.

I

Impaction is the condition of a tooth being blocked from ERUPTING, or growing into the mouth, by a physical barrier. This barrier is usually another tooth. If there is OVERCROWDING present i.e. not enough space for the teeth to grow into the correct position, this may lead to the impaction or wedging of teeth in the bone.

WISDOM TEETH, that is the teeth at the very back of the mouth, are frequently impacted and may cause quite severe problems for the patient. This includes pain, discomfort, and possibly limited opening of the mouth, as well as RESORPTION and CARIES in the teeth in front of them. It is often necessary for IMPACTED WISDOM TEETH to be SURGICALLY REMOVED as a result.

If this does become necessary, your dentist may advise you to have special ANAESTHETICS, and even possibly a stay in hospital for a few days. This is not necessary in most cases, however.

Implant

Although implants are not a new type of treatment, their development into the general sphere of dental practice has been remarkably pronounced in recent years. An implant is a metal pin, blade or casting which is insert into, or placed on top of, the bone of the upper or lower jaw to provide ANCHORAGE or stabilization either to teeth or PROSTHESIS. An ENDOSTEAL ( Endosseous) implant is one which is introduced into the maxilla or mandible so that part of it protrudes into the mouth. Implants usually consist of 3 sections; 1. the body, which is placed into the bone, 2. the abutment, which is the section visible in the mouth which supports or retains the prosthesis and, 3. the superstructure to which other components of the prosthesis are attached.

Infection Control

These are the procedures and protocols designed to prevent or limit cross contamination in health-care environments, and to prevent the transmission of infection from one patient to another. These procedures are, in the dental practice, relevant in not only the surgery itself, but all other areas of the dental office like recovery rooms, waiting rooms, rest rooms, and so on. CROSS INFECTION is defined one which is transmitted between individuals who are infected with different PATHOGENIC MICROORGANISMS.

Inlay

This is a RESTORATION of metal, fired porcelain, or plastic made outside a tooth to fit into a tapered CAVITY PREPARATION and fastened or LUTED into it with a cementation medium.

Inlays can be divided by how they are produced into DIRECT and INDIRECT types. In the DIRECT sort, the pattern for the inlay is made in the mouth from the patient's teeth. In the INDIRECT form, an accurate IMPRESSION of the mouth is made, models constructed, and the pattern made up (usually in wax) on this model.

J

K

L

M

N

This form of caries or tooth decay is found in the DECIDUOUS dentition and is related, as expected, to the incorrect use of nursing bottles and the liquids in them. Nusring bottle caries affects typically the anterior teeth in the upper arch while the lower teeth remain unaffected as they are protected by the tongue while the infant is sucking the bottle.

The cause of tooth decay is the presence of bacteria, and sugars in the mouth over extended periods of time. (see section on CARIES ) In the above situation, a nursing bottle is allowed to stay in the child's mouth over long periods, usually as a soothing mechanism to induce sleep, and because of this, the rate of caries development is fast and severe. Because the PRIMARY dentition is also less mineralized and therefore 'weaker' than the permanent dentition, the caries is particularly aggressive and pronounced. The amount of sugar in the liquid in a baby's bottle is crucial to the rate of caries formation. Fruit juices, although a 'natural' product, are particularly high in sugars, and there are many other products on the market for babies which will cause damage to the teeth. The precaution of reading the product contents should always be taken, and anything with sugar, fructose, or lactose rejected. Pure water is the best filler if the use of a nursing bottle cannot otherwise be avoided.

Treatment of this type of caries is notoriously difficult and unpleasant for all concerned. Because of the young age of the patient the treatment is often the first introduction to the dental practice environment, and the extensive nature of the work required means that it is especially traumatic for the child, the family and the dental team. In extreme cases, the use of GENERAL ANAESTHETICS may be necessary, which increase the risk to the patient's health and general well-being. Parents must be especially vigilant and determined to avoid this type of caries, as they thereby prevent enormous amounts of trauma, especially psychological, to their children.

Methods of prevention include the avoidance of nursing bottles if possible, the correct types of liquids being drunk, regular and correct toothbrushing techniques ( see PREVENTIVE DENTISTRY section ) and, where necessary, the use of FLUORIDE diet supplements and treatments. Your dentist or hygienist will be able to offer you advice on prevention and hygiene.

O

(Also sometimes called an OVERLAY) An onlay is a cast RESTORATION retained by friction, mechanical factors, and cementation in a specially prepared tooth, which replaces one or more CUSPS and adjoining structures of the tooth.

This term may also be used to describe part of a REMOVABLE PARTIAL DENTURE which is extended over the entire OCCLUSAL surface of a tooth to provide extra support to the appliance.

Orthodontics

Orthodontics is that branch of dentistry which is concerned with the growth, development, and treatment of malformations of dentofacial structures. It may include the movement of teeth or facial bones through the application of forces and/ or the stimulation and redirection of functional forces within the CRANIOFACIAL COMPLEX.

ORTHODONTIC TREATMENT is frequently carried out on children in their childhood and teenage years as this is the most effective time to alter the position and growth patterns of the mouth and jaws. Adult orthodontics is, however, increasingly common, and improved understanding and techniques means that this form of treatment is available to ever larger numbers of people.

Orthodontic treatment is generally carried out with the use of a BRACE or ORTHODONTIC APPLIANCE which is either removable or fixed in the mouth, (generally by being bonded onto the teeth.) There are very many different styles and forms of appliances, most of which are worn inside the mouth, but some which include external parts like HEADGEAR.

Orthodontic appliances are generally made of metal or plastic wires and BRACKETS, sometimes with acrylic sections, and sometimes even with elastic bands to apply forces.

Orthodontic treatment generally aims not only to improve the functioning of the mouth and jaws, but also the appearance of the face by improving the alignment of the teeth and related bone structures.

Orthognathic surgery

This is the type of major surgery which deals with the cause and treatment of malpositioning of the jaws. The surgery is usually carried out to alter the position of the dental ARCHES and/ or the supporting structures, and is frequently done in combination with ORTHODONTIC treatment. The surgeons who carry out these types of treatment will have undergone extensive training, as this is a very specialized field of dentistry.

Overbite

The overlap between the upper INCISORS ( front teeth ) and the lower incisors in a vertical plane. Also sometimes called the VERTICAL OVERLAP. Normally between 2 and 4 millimetres.

Overdenture

Also known as a TELESCOPIC DENTURE, or an OVERLAY DENTURE. This is a removable partial or complete denture which has secondary COPINGS or fixtures, which telescope (fit) over primary copings prepared in natural teeth, or on posts or on studs.

Overjet

The horizontal projection of the upper INCISORS ( front teeth ) beyond the lower incisors when the teeth are held together. Usually 2 to 4 millimetres. Also called the HORIZONTAL OVERLAP, the HORIZONTAL OVERBITE, and less frequently, the overjut.

P

Some types of ORTHODONTIC APPLIANCE have these devices fitted, which are designed to increase the width between the teeth in the upper arch by expanding the palate or by tilting the upper teeth. Often the patient needs to adjust the EXPANDER herself between visits to the orthodontist, and this will be explained in detail by the doctor or nurse before she starts treatment. As each patient is different, so the instructions for use of the palatal expander will be different. If there is any doubt what needs to be done, the patient should contact the ORTHODONTIST before making any adjustment herself.

Panoramic X-ray

A panoramic x-ray is a radiograph taken outside the mouth to show the entire upper and lower jaws (maxilla and mandible) in one continuous film.

Partial Denture

A partial denture is a removable artificial or PROSTHETIC substitute for missing natural teeth and adjacent tissues which does not include the replacement of all the teeth in the ARCH.

There are many different sorts and classifications ( most commonly by the KENNEDY SYSTEM ) and methods of construction. Common materials used in their construction include DENTAL ACRYLIC, ALLOYS OF METAL including COBALT CHROME, GOLD, and many more. Partial dentures may be tooth supported ( i.e. relying on the tooth substance for support via a system of rests and clasps ) or mucosal supported, ( i.e. relying on the gums and soft tissues for support ) or a combination of the two. Partial dentures must be carefully designed and constructed within certain guidelines so that they do not cause destruction of the remaining and supporting structures of the mouth.

People who have been provided with partial dentures will often be specially advised how to clean them and their remaining teeth correctly. Wearing any form of tooth replacement, like dentures or bridges, means extra care must be taken with oral hygiene as PLAQUE will collect differently around them. Ask your dentist or hygienist for advice.

Periodontal disease\periodontitis\gum disease

Periodontitis involves inflammation of the gingiva which progresses to infection of the bone and supporting tissue. Left untreated, it may lead to loss of periodontal ligament attachment, and loss of bone resulting in mobility(loosening of the teeth), and eventual tooth loss.

Periodontal disease as usually a slowly progressing disease of middle and old age. It is a chronic disease which can be kept under control but not "cured". Periodontitis may also occur in children where it mostly affects the first permanent molars and incisors.

The symptoms of periodontal disease include swelling and bleeding gums, receding gums, exudate(pus) from the gums, halitosis(bad breath), splaying or pushing outwards of the upper front incisors, and mobile loose teeth.

The treatment for periodontitis most often includes scaling and root plaing (deep cleaning) and possibly gum surgery. Thorough home oral care and continued regular maintenance care by your dentist is also very important for periodontal health.

Periodontal pocket

The periodontal pocket is the space between the gum and the tooth as associated with periodontitis. The deepening space is cause by the destruction of the peridontal ligament attachment and supporting tissues. The pocket is often lined with ulcerated and inflamed tissue. As the pocket becomes deeper, it becomes more and more difficult to clean out accumulated plaque and calculus.

Measuring the depth of pockets with a periodontal probe and assessing the presence of blood or pus in the pockets are different ways your dentist can evaluate your periodontal health.

Plaque

Plaque is the sticky soft thin film on tooth surfaces composed of food debris and bacteria. Accumulation of dental plaque is responsible for the formation of cavities, gingivitis and periodontal disease. Because plaque is so sticky, it can not just be rinsed off your teeth; it must be mechanically removed. Toothbrushing and flossing mechanically remove plaque.

Your dentist can evaluate how well you remove the plaque by using a Plaque Index. After chewing colored disclosing tablets, the dentist counts and evaluates the colored areas on your teeth where plaque is remaining to arrive at a plaque index score. After learning correct brushing and flossing methods your plaque index score should improve.

Precision attachment

An interlocking mechanical device in which one part (the female) is fixed to an ABUTMENT, either inside or outside the CROWN of a tooth, and the other part (the male) is integrated into a BRIDGE or DENTURE. Precision attachments provide extra support in the form of retention or stabilization to the appliance. There are very many different sorts of precision attachments, like Huster, Mccollum, Dalbo, ball and socket, bar, to name but a few.

Preventive Dentistry

Preventive dentistry involves the dental care and health programs given to prevent the onset of disease in the mouth. It includes teaching good home oral cleaning care, diet advice, regular oral prophylaxis (cleaning), fluoride treatments, and sealants.

Primary, Deciduous or Baby teeth

These are the 20 teeth of the first dentition which are shed and replaced by the PERMANENT or adult dentition. They begin to form when the baby is still in the womb, and first appear in the mouth around 6 months of age. The first teeth to appear are usually, but not always the lower front INCISORS, and these are followed by the upper incisors and then the POSTERIOR or deciduous molars. By the time the child is about two and a half years old, all the deciduous teeth should have 'erupted' or appeared in the mouth, although the timing, sequence and position of the teeth is not always totally predictable.

Many children have difficulty when the baby teeth are erupting, and this may take the form of irritability, sleeplessness, tiredness, areas of slight ulceration in the mouth, and even diarrhea. There are many preparations available from the dentist, chemist or doctor to help the baby get over this difficult time. The primary teeth are smaller, and of a different shape and form, relative to the PERMANENT dentition. They are whiter but also less mineralized than the adult teeth, and this means that they are also more susceptible to CARIES.

Probe

A periodontal probe is a blunt ended slender instrument used to measure the depth of periodontal pockets. The measurements are usually in millimeters. Bleeding of tissue or the presence of pus upon probing are also used as guides to evaluate periodontal health.

Prophylaxis/cleaning

A prophylaxis is a preventive treatment, also known as a cleaning, involving removal of plaque, calculus, debris and stain from teeth above the gumline. A comprehensive prophylaxis also includes any necessary X-rays to help detect decay formation, checking restorations present for defects and overhangs, examination of the gums to check for periodontal health, checking for areas of food impaction, plaque detection using colored disclosing tablets or solution, and application of topical fluoride to prevent decay formation.

It is recommended to have a dental prophylaxis every 6 months to help prevent the onset of periodontal disease and detect any decay formation in its early stages.

Prosthodontics

Prosthodontics is that branch of dentistry which is involved in the restoration and maintenance of oral function, comfort, appearance, and health of the patient by the replacement of missing teeth or tissues by artificial means. Also called PROSTHETIC DENTISTRY, DENTAL PROSTHETICS, and DENTURE PROSTHETICS.

A dentist who specializes in this field is called a PROSTHODONTIST. PROSTHETIC SURGERY or PRE- PROSTHETIC SURGERY is that required before or during the provision of prosthetic treatment.

Pulpotomy

A PULPOTOMY is a type of ENDODONTIC treatment, which involves the removal of part of a vital PULP. The PULP is the living part of the tooth which is contained in the inner ROOT CANALS and PULP CHAMBER, and contains nerves and blood vessels, amongst other things. A PULPOTOMY ( also called PULP AMPUTATION :old name; PARTIAL PULPECTOMY ) removes diseased tissue and leaves healthy tissue behind to allow healing or growth of a root. The treatment is often carried out on PRIMARY or DECIDUOUS (MILK / BABY teeth), or on young adult teeth, and will be recommended to you if your dentist thinks it is the treatment of choice.

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Radiolucent objects are of low density, absorb radiation and appear as dark gray to black on x-ray film. Some examples of radioluscent objects are pulp, gingiva, and decayed tooth structure.

Radiopaque

Radiopaque objects are of high density and do not absorb radiation. They are viewed as white or light areas on x-ray film. Some examples of radiopaque objects are metal, dense bone, and enamel.

Root Canal Treatment / Endodontics

The root canals of a tooth are the parts of the PULP CAVITY which lie within the roots, and in a healthy tooth contain the vital pulp tissues. The PULP is made up of nerves and blood vessels, lymph systems and other vital structures, and amongst other things, is responsible for transmitting feelings of pain within the teeth. Root canals are different shapes in each tooth; they are different between different people and races, and they also change their shape as you get older. Root canals may be made up of just one main channel, or more usually, of several different channels, which may or may not have smaller side channels branching off them. ENDODONTICS is the study and treatment of root canal and pulp systems, and their related structures.

If a tooth becomes diseased or painful, and this may happen for a number of reasons, ENDODONTIC or ROOT CANAL TREATMENT may be considered necessary. Likely causes may be; extensive CARIES, TRAUMA, severe PERIODONTAL disease, extensive or large RESTORATION work. This often leads to the death of the pulp tissue, which may or may not be noticed by the patient in the form of pain. A pulp may die straight away after trauma or treatment, or may take days, weeks or years to die. Sometimes your dentist may decide that it is best to remove a vital or living pulp, or even to use some medication to cause the death of the pulp if that will help the treatment. Either way, you may or may not have pain during the treatment. Even after the pulp has been removed or has died, a tooth may still be painful due to nerves being affected in the surrounding tissues. Your dentist should be able to offer you treatment to alleviate pain, which may include ANALGESICS or pain killers, topical or local medications, and possibly ANTIBIOTICS to reduce severe infections. The treatment may last over a few minutes or a few days, or even a few weeks, depending on what caused the problem. The duration of treatment is also affected by how long the problem has been present and how difficult the treatment processes are.

Your dentist will normally require a number of X- RAYS or RADIOGRAPHS during the course of the endodontic treatment so that she may see how the various stages are progressing, and whether or not the treatment is successful.

You cannot provide any homecare which will treat root canals, but you should follow the instructions of your dentist carefully during treatment if it is to be successful. This may include the taking of medication, the way you eat and clean your mouth, and the times and frequency of appointments.

Rubber Dam / Dental Dam

A rubber dam is a sheet of latex rubber which is placed over teeth during treatment to isolate them from the rest of the mouth. It is an extremely useful way to keep the area of work clean and safe, and also prevents the patient from inhaling or swallowing instruments which may be dangerous. During the removal of old amalgam fillings, it may be used to reduce the amount of metal swallowed, and therefore the contamination to the patient. The dam is held in place usually by a little clamp around the tooth or teeth, as well as dental floss, and is removed after treatment.

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A scaler is an instrument used by hand to remove plaque and calculus from tooth surfaces above the gumline.

Scaling and Root Planing

Scaling involves the removal of plaque and calculus from tooth surfaces. It removes these irritants to the gum tissues and allows healing to occur. Scaling below the gum line is often referred to as a deep clean.

Scaling is often combined with root planing. Root planing is the meticulous cleaning and smoothing of root surfaces. Inflammation of the tissues is reduced which helps the gum tissues to return to a healthy state.

Sealant

A sealant is a protective coating formed by resin bonded into the deep pit and fissure grooves on the occlusal (biting) surfaces of molar and premolar teeth. A sealant helps to prevent formation of decay by blocking the accumulation of food, debris and bacteria in these vulnerable areas.

Serial Extraction

This is an ORTHODONTIC procedure in which PRIMARY or DECIDUOUS teeth are removed over a period of years in a particular sequence to prevent or relieve OVERCROWDING of the PERMANENT teeth when they ERUPT or come through into the mouth. At the end of a serial extraction procedure, it may still be necessary to remove some permanent teeth, but the crowding will have been localized, and the orthodontic treatment then needed will be less than otherwise would have been necessary.

Also called SELECTED or PROGRESSIVE extraction

Space maintainer

A removable or fixed appliance designed to maintain an existing space in a DENTAL ARCH. Space maintainers are usually fitted in children when they have lost DECIDUOUS or baby teeth early, and the gap left needs to be held open to allow the PERMANENT or adult tooth to erupt in the correct position. There are many different designs of space maintainer, and the materials normally used are metal or acrylic.

Sterilization

This is a process in which a surface or instrument is rendered free from viable (ie.living) germ life.( microorganisms) There are several effective ways to achieve this state, for example using AUTOCLAVE EQUIPMENT ( see notes above ), using a DRY HEAT sterilization process
( 160℃ ) for one hour, using certain types of GAMMA RAYS, or ETHYLENE OXIDE gas, and so on. All instruments in a dental practice should be sterilized before use between the patients the dentist sees. This is to prevent contamination and CROSS INFECTION.

An alternative regime for complete sterilization is 12 minutes at 134℃, in an autoclave.

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Also known as an INTERMEDIATE restoration, this type of tooth filling is used to restore the form, function or appearance of the teeth for a limited period of time, from several days to several months. Temporary restorations are designed to seal a tooth and maintain it's position until a permanent restoration will replace it.

There are many different sorts of materials used, for example, GUTTA PERCHA, ZINC PHOSPHATE, ZINC OXIDE-EUGENOL. Some of the temporary restorations may be indicated as PALLIATIVE treatment, for example during ROOT CANAL TREATMENT to soothe a PULPAL lesion, or in cases of RAMPANT CARIES to stabilize the teeth and alter the oral flora.( bacteria predominant in the mouth.)

Toothbrushing

The Bass method is a preferred method of brushing. It involves placing the tooth brush head at a 45 degree angle along the gumline, pointing downwards on the bottom teeth and upwards on the top teeth. The tips of the toothbrush bristles should go underneath the gumline. The toothbrush is gently vibrated, not scrubbed, along the gumline spending about 3 seconds on each tooth. The entire process of brushing should last 3-4 minutes (about the length of one song on the radio!)

Toothpaste

Dentifrice is the toothpaste, powder, liquid or gel that is used with a toothbrush to clean teeth. It contains a mild abrasive, detergent, flavoring agent, humectant (retains water) and various medicaments designed to prevent tooth decay. Only a pea sized amount of dentrifice is recommended to be placed on the toothbrush. The actual mechanical action of brushing is more important than the tooth paste used. However a toothpaste containing fluoride helps to significantly reduce tooth decay.

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An ultrasonic cleaner is an instrument which transmits high frequency vibrations to remove large deposits of plaque, calculus and debris from tooth surfaces. Water is used with the ultrasonic cleaner to cool the tooth and flush away debris. Hand instrument cleaning is often necessary following ultrasonic cleaning to thoroughly clean off tooth surfaces.

V

A veneer is a thin layer of tooth coloured material, usually porcelain or acrylic resin, which is attached to the surface of a tooth by direct fusion, cementation, or mechanical retention. When used without qualification, the term now usually means a thin layer of porcelain which is bonded onto the slightly prepared front surface of a tooth to improve the appearance. The colour and shape of teeth may be dramatically improved with veneers, which have the advantage over CROWNS of requiring less reduction of the natural tooth tissue. However, not all cases where crowns are a possibility, are suitable for veneers. Your dentist will advise you on whether veneers are the treatment of choice for you.

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An x-ray or radiograph is an image produced on film following exposure of an object to x-radiation. The image produced is based upon the density and absorption of radiation of the object.

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