Tooth whitening or tooth bleaching is the process of lightening the color of
human teeth
The human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. As such, they are considered part of the human digestive system. Humans have four types of teeth: incis ...
. Whitening is often desirable when teeth become yellowed over time for a number of reasons, and can be achieved by changing the intrinsic or extrinsic color of the
tooth enamel
Tooth enamel is one of the four major Tissue (biology), tissues that make up the tooth in humans and many other animals, including some species of fish. It makes up the normally visible part of the tooth, covering the Crown (tooth), crown. The ...
. The chemical degradation of the
chromogen
In chemistry, the term chromogen refers to a colourless (or faintly coloured) chemical compound that can be converted by chemical reaction into a compound which can be described as "coloured". There is no universally agreed definition of the term. ...
s within or on the tooth is termed as bleaching.
Hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...
() is the active ingredient most commonly used in whitening products and is delivered as either hydrogen peroxide or
carbamide peroxide
Hydrogen peroxide - urea (also called Hyperol, artizone, urea hydrogen peroxide, and UHP) is a solid composed of equal amounts of hydrogen peroxide and urea. This compound is a white crystalline solid which dissolves in water to give free hydroge ...
. Hydrogen peroxide is analogous to carbamide peroxide as it is released when the stable complex is in contact with water. When it diffuses into the tooth, hydrogen peroxide acts as an
oxidising agent
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...
that breaks down to produce unstable
free radicals
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron.
With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spont ...
. In the spaces between the inorganic salts in tooth enamel, these unstable free radicals attach to organic pigment molecules resulting in small, less heavily pigmented components. Reflecting less light, these smaller molecules create a "whitening effect". There are different products available on the market to remove stains. For whitening treatment to be successful, dental professionals (
dental hygienist
A dental hygienist or oral hygienist is a licensed dental professional, registered with a dental association or regulatory body within their country of practice. Prior to completing clinical and written board examinations, registered dental hygien ...
or
dentist
A dentist, also known as a dental surgeon, is a health care professional who specializes in dentistry (the diagnosis, prevention, management, and treatment of diseases and conditions of the mouth, oral cavity and other aspects of the craniofaci ...
) should correctly diagnose the type, intensity and location of the tooth discolouration. Time exposure and the concentration of the bleaching compound, determines the tooth whitening endpoint.
Natural shade
The perception of tooth colour is multi-factorial. Reflection and absorption of light by the tooth can be influenced by a number of factors including specular transmission of light through the tooth;
specular reflection
Specular reflection, or regular reflection, is the mirror-like reflection of waves, such as light, from a surface.
The law of reflection states that a reflected ray of light emerges from the reflecting surface at the same angle to the surf ...
at the surface; diffuse light reflection at the surface; absorption and scattering of light within the dental tissues; enamel mineral content; enamel thickness; dentine colour, the human observer, the fatigue of the eye, the type of incident light, and the presence of extrinsic and intrinsic stains. Additionally, the perceived brightness of the tooth can change depending on the brightness and colour of the background.
The combination of intrinsic colour and the presence of extrinsic stains on the tooth surface influence the colour and thus the overall appearance of teeth. The scattering of light and absorption within enamel and
dentin
Dentin () (American English) or dentine ( or ) (British English) ( la, substantia eburnea) is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth. It is usually covered by ena ...
e determine the intrinsic colour of teeth and because the enamel is relatively translucent, the dentinal properties can play a major role in determining the overall tooth colour. On the other hand, extrinsic stain and colour is the result of coloured regions that have formed within the acquired pellicle on the enamel surface and can be influenced by lifestyle behaviours or habits. For example, dietary intake of
tannin
Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.
The term ''tannin'' (from Anglo-Norman ''tanner'', ...
-rich foods, poor
tooth brushing
Tooth brushing is the act of scrubbing teeth with a toothbrush, usually equipped with toothpaste. Interdental cleaning (with floss or an interdental brush) can be useful with tooth brushing, and together these two activities are the primary me ...
technique,
tobacco
Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
products, and exposure to iron salts and
chlorhexidine
Chlorhexidine (CHX) (commonly known by the salt forms chlorhexidine gluconate and chlorhexidine digluconate (CHG) or chlorhexidine acetate) is a disinfectant and antiseptic that is used for skin disinfection before surgery and to sterilize surgi ...
can darken the colour of a tooth.
With increasing age, teeth tend to be darker in shade. This can be attributed to secondary dentin formation and thinning of enamel due to
tooth wear
Tooth wear refers to loss of tooth substance by means other than dental caries. Tooth wear is a very common condition that occurs in approximately 97% of the population. This is a normal physiological process occurring throughout life; but with in ...
which contributes to a significant decrease in lightness and increase in yellowness. Tooth shade is not influenced by gender or race.
Staining and discolouration
Tooth discolouration and staining is primarily due to two sources of stain: intrinsic and extrinsic (see Figure 2). In essence, tooth whitening primarily targets those intrinsic stains in which cannot be removed through mechanics such as a debridement (clean) or
prophylaxis
Preventive healthcare, or prophylaxis, consists of measures taken for the purposes of disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental hea ...
, in the dental office. Below explains in-depth the differences between the two sources of which contribute to such discolouration of the tooth's surface.
Extrinsic staining
Extrinsic staining, is largely due to environmental factors including smoking, pigments in beverages and foods, antibiotics, and metals such as iron or copper. Coloured compounds from these sources are adsorbed into acquired dental pellicle or directly onto the surface of the tooth causing a stain to appear.
*
Dental plaque
Dental plaque is a biofilm of microorganisms (mostly bacteria, but also fungi) that grows on surfaces within the mouth. It is a sticky colorless deposit at first, but when it forms tartar, it is often brown or pale yellow. It is commonly found bet ...
: Dental plaque is a clear
biofilm
A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...
of
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
that naturally forms in the mouth, particularly along the
gumline
The gums or gingiva (plural: ''gingivae'') consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health.
Structure
The gums are part of the soft tissue linin ...
, and it occurs due to the normal development and defences of the immune system. Although usually virtually invisible on the tooth surface, plaque may become stained by chromogenic bacteria such as ''
Actinomyces
''Actinomyces'' is a genus of the Actinomycetia class of bacteria. They all are gram-positive. ''Actinomyces'' species are facultatively anaerobic and they grow best under anaerobic conditions. ''Actinomyces'' species may form endospores, an ...
'' species. Prolonged dental plaque accumulation on the tooth surface can lead to enamel demineralisation and formation of white spot lesions which appear as an opaque milk-coloured lesion. The acidic by-products of fermentable
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
s derived from high-sugar foods contribute to greater proportions of bacteria, such as ''
Streptococcus mutans
''Streptococcus mutans'' is a facultatively anaerobic, gram-positive coccus (round bacterium) commonly found in the human oral cavity and is a significant contributor to tooth decay.
It is part of the " streptococci" (plural, non-italic lowercase ...
'' and ''
Lactobacillus
''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically diver ...
'' in dental plaque. Higher consumption of fermentable carbohydrates will promote demineralisation and increase the risk of developing white spot lesions.
*
Calculus
Calculus, originally called infinitesimal calculus or "the calculus of infinitesimals", is the mathematical study of continuous change, in the same way that geometry is the study of shape, and algebra is the study of generalizations of arithm ...
: neglected plaque will eventually calcify, and lead to the formation of a hard deposit on the teeth, especially around the gumline. The organic matrix of dental plaque and calcified tissues undergo a series of chemical and morphological changes that lead to calcification of the dental plaque and therefore leading to the formation of calculus. The color of calculus varies, and may be grey, yellow, black, or brown. The colour of calculus depends on how long it has been present in the oral cavity for; it typically starts off yellow and over time the calculus will begin to stain a darker colour and become more tenacious and difficult to remove.
*
Tobacco
Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
:
tar
Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. "a dark brown or black bit ...
in the smoke from tobacco products (and also
smokeless tobacco
Smokeless tobacco is a tobacco products, tobacco product that is used by means other than smoking. Their use involves chewing, sniffing, or placing the product between gum and the cheek or lip. Smokeless tobacco products are produced in various f ...
products) tends to form a yellow-brown-black stain around the necks of the teeth above the gumline. The
nicotine
Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...
and tar in tobacco, combined with oxygen, turns yellow and over time will absorb into the pores of enamel and stain the teeth yellow. The dark brown to black stains along the gum line of the teeth are the result of the porous nature of calculus immediately picking up the stains from nicotine and tar.
*
Betel
The betel (''Piper betle'') is a vine of the family Piperaceae, which includes pepper and kava. The betel plant is native to Southeast Asia. It is an evergreen, dioecious perennial, with glossy heart-shaped leaves and white catkins. Betel plan ...
chewing. Betel chewing produces blood-red saliva that stains the teeth red-brown to nearly black. The extract gel of betel leaf contain tannin, a chromogenic agent that causes discolouration of the tooth enamel.
* Tannin is also present in coffee, tea, and red wine and produces a chromogenic agent that can discolor teeth. Large consumptions of tannin-containing beverages stain the dental enamel brown due to the chromogenic nature.
* Certain foods, including curries and tomato-based sauces, can cause teeth staining.
* Certain topical medications:
Chlorhexidine
Chlorhexidine (CHX) (commonly known by the salt forms chlorhexidine gluconate and chlorhexidine digluconate (CHG) or chlorhexidine acetate) is a disinfectant and antiseptic that is used for skin disinfection before surgery and to sterilize surgi ...
(antiseptic mouthwash) binds to tannins, meaning that prolonged use in persons who consume coffee, tea or red wine is associated with extrinsic staining (i.e. removable staining) of teeth. Chlorhexidine mouthwash has a natural liking for sulphate and acidic groups commonly found in areas where plaque accumulates such as along the gumline, on the dorsum of the
tongue
The tongue is a muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper surfa ...
and cavities. Chlorhexidine is retained in these areas and stain yellow-brown. The stains are not permanent and can be removed with proper brushing.
* Metallic compounds. Exposure to such metallic compounds may be in the form of medication or occupational exposure. Examples include iron (black stain), iodine (black), copper (green), nickel (green), and cadmium (yellow-brown). Sources of exposure to metal include placing metal into the oral cavity, metal-containing dust inhalation, or oral administration of drugs. Metals can enter the bony structure of the tooth, causing permanent discolouration, or can bind to the pellicle causing surface stain.
Removal of extrinsic staining
Extrinsic staining may be removed through various treatment methods:
*
Prophylaxis
Preventive healthcare, or prophylaxis, consists of measures taken for the purposes of disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental hea ...
: dental prophylaxis includes the removal of extrinsic staining using a slow-speed rotary handpiece and a rubber cup with abrasive paste, mostly containing
fluoride
Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts typ ...
. The abrasive nature of the prophy paste, as it is known, acts to remove extrinsic staining using the action of the slow-speed handpiece and the paste against the tooth. Adversely, the action of the rubber cup together with the abrasive nature of the paste, removes around one
micron
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...
of enamel from the tooth surface every time a prophylaxis is performed. This method of stain removal may only take place in the dental office.
* Micro-abrasion: allows a dental professional to make use of an instrument which emits a powder, water and compressed air to remove biofilm, and extrinsic staining. This stain removal method can only be undertaken in a dental office, not at home.
*
Toothpaste
Toothpaste is a paste or gel dentifrice used with a toothbrush to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from the teeth, a ...
: there are many available on the market that implement both peroxide as well as abrasive particles, such as
silica gel
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other l ...
, to help remove extrinsic stains, while the peroxide acts on intrinsic staining. This method of stain removal may take place at home as well as in a dental office.
Intrinsic staining
Intrinsic staining primarily occurs during the tooth development either before birth or at early childhood. Intrinsic stains are those that cannot be removed through mechanical measures such as debridement or a prophylactic stain removal. As the age of the person increases, the teeth can also appear yellower over time. Below are examples of intrinsic sources of stains:
*
Tooth wear
Tooth wear refers to loss of tooth substance by means other than dental caries. Tooth wear is a very common condition that occurs in approximately 97% of the population. This is a normal physiological process occurring throughout life; but with in ...
and aging: Tooth wear is a progressive loss of enamel and dentine due to tooth erosion, abrasion and
attrition
Attrition may refer to
*Attrition warfare, the military strategy of wearing down the enemy by continual losses in personnel and material
**War of Attrition, fought between Egypt and Israel from 1968 to 1970
**War of attrition (game), a model of agg ...
. As enamel wears down, dentine becomes more apparent and chromogenic agents are penetrated in the tooth more easily. The natural production of secondary dentine also gradually darkens teeth with age.
*
Dental cavities
Dental may refer to:
* Dental consonant, in phonetics
* Dental Records, an independent UK record label
* Dentistry, oral medicine
* Teeth
See also
*
* Dental care (disambiguation)
* Dentist (disambiguation)
* Tooth (disambiguation)
A tooth (pl ...
(tooth decay): The evidence regarding carious tooth discolouration is inconclusive, however the most reliable evidence suggests that carious lesion allows for exogenous agents to enter dentine and hence increased absorption of chromogenic agents causing discolouration to the tooth.
* Restorative materials: The materials used during
root canal treatment
Root canal treatment (also known as endodontic therapy, endodontic treatment, or root canal therapy) is a treatment sequence for the infected pulp of a tooth which is intended to result in the elimination of infection and the protection of ...
s, such as
eugenol
Eugenol is an allyl chain-substituted guaiacol, a member of the allylbenzene class of chemical compounds. It is a colorless to pale yellow, aromatic oily liquid extracted from certain essential oils especially from clove, nutmeg, cinnamon, basil ...
and phenolic compounds, contain pigment that stain dentine. Restorations using
amalgam
Amalgam most commonly refers to:
* Amalgam (chemistry), mercury alloy
* Amalgam (dentistry), material of silver tooth fillings
** Bonded amalgam, used in dentistry
Amalgam may also refer to:
* Amalgam Comics, a publisher
* Amalgam Digital
...
also penetrate dentine tubules with tin over time therefore causing dark stains to the tooth.
* Dental trauma which may cause staining either as a result of
pulp necrosis Pulp necrosis is a clinical diagnostic category indicating the death of the pulp and nerves of the pulp chamber and root canal of a tooth which may be due to bacterial sequelae, trauma and chemical or mechanical irritation. It is often the end resul ...
or internal resorption. Alternatively the tooth may become darker without pulp necrosis.
*
Enamel hypoplasia
Enamel hypoplasia is a defect of the teeth in which the enamel is deficient in quantity, caused by defective enamel matrix formation during enamel development, as a result of inherited and acquired systemic condition(s). It can be identified as m ...
: Enamel hypoplasia causes enamel to be thin and weak. It produces a yellow-brown discolouration and can also cause the enamel's smooth surface to be rough and pitted which causes the tooth to be susceptible to extrinsic staining, tooth sensitivity, malocclusion, and dental cavities. The evidence regarding enamel hypoplasia is inconclusive, however the most likely cause is infection or trauma caused to the primary dentition. Disturbances to the developing tooth germ during neonatal and early childhood stages such as maternal
vitamin D deficiency
Vitamin D deficiency or hypovitaminosis D is a vitamin D level that is below normal. It most commonly occurs in people when they have inadequate exposure to sunlight, particularly sunlight with adequate ultraviolet B rays (UVB). Vitamin D defic ...
, infection, and medication intake can cause enamel hypoplasia.
* Pulpal hyperemia: Pulpal hyperemia refers to inflammation of a traumatised tooth which can be caused by a stimuli such as trauma, thermal shock, or dental cavities. Pulpal hyperemia is reversible and produces a red hue seen initially after trauma which has the ability to disappear if the tooth becomes revascularized.
* Fluorosis: Dental fluorosis causes enamel to become opaque, chalky white, and porous. The enamel can break down and cause the exposed subsurface enamel to become mottled and produce extrinsic dark brown-black stains. Dental fluorosis occurs due to excessive ingestion of fluoride or overexposure to fluoride during the development of enamel which usually occurs between the ages of one to four. Fluoridated drinking water, fluoride supplements, topical fluoride (fluoride toothpastes), and formula prescribed for children can increase the risk of dental fluorosis. Fluoride is considered an important factor in the management and prevention of dental cavities, the safe level for daily fluoride intake is 0.05 to 0.07 mg/kg/day.
*
Dentinogenesis imperfecta
Dentinogenesis imperfecta (DI) is a genetic disorder of tooth development. It is inherited in an autosomal dominant pattern, as a result of mutations on chromosome 4q21, in the dentine sialophosphoprotein gene (DSPP). It is one of the most frequen ...
: Dentinogenesis imperfecta is a
hereditary
Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic inform ...
dentine defect, associated with
osteogenesis imperfecta
Osteogenesis imperfecta (; OI), colloquially known as brittle bone disease, is a group of genetic disorders that all result in bones that break easily. The range of symptoms—on the skeleton as well as on the body's other organs—may be mi ...
, which causes the tooth to become discoloured usually blue or brown in colour and translucent giving teeth an opalescent sheen. The condition is
autosomal dominant
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
which means that the condition runs in the family.
*
Amelogenesis imperfecta
Amelogenesis imperfecta (AI) is a congenital disorder which presents with a rare abnormal formation of the enamel or external layer of the crown of teeth, unrelated to any systemic or generalized conditions. Enamel is composed mostly of mineral, ...
: The appearance of amelogenesis imperfecta depends on the type of
amelogenesis
Amelogenesis is the formation of enamel on teeth and begins when the crown is forming during the advanced bell stage of tooth development after dentinogenesis forms a first layer of dentin. Dentin must be present for enamel to be formed. Amelobla ...
, there are 14 different subtypes and can vary from the appearance of hypoplasia to hypomineralisation which can produce different appearances of enamel from white mottling to yellow brown appearances.
*
Tetracycline
Tetracycline, sold under various brand names, is an oral antibiotic in the tetracyclines family of medications, used to treat a number of infections, including Acne vulgaris, acne, cholera, brucellosis, plague (disease), plague, malaria, and sy ...
and
minocycline
Minocycline, sold under the brand name Minocin among others, is a tetracycline antibiotic medication used to treat a number of bacterial infections such as pneumonia. It is generally less preferred than the tetracycline doxycycline. It is also ...
. Tetracycline is a
broad-spectrum antibiotic
A broad-spectrum antibiotic is an antibiotic that acts on the two major bacterial groups, Gram-positive and Gram-negative, or any antibiotic that acts against a wide range of disease-causing bacteria. These medications are used when a bacterial inf ...
, and its derivative minocycline is common in the treatment of
acne
Acne, also known as ''acne vulgaris'', is a long-term Cutaneous condition, skin condition that occurs when Keratinocyte, dead skin cells and Sebum, oil from the skin clog hair follicles. Typical features of the condition include comedo, black ...
. The drug is able to chelate calcium ions and is incorporated into teeth, cartilage, and bone. Ingestion during the years of tooth development causes yellow-green discoloration of dentine visible through the enamel which is fluorescent under
ultraviolet light
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
. Later, the tetracycline is oxidized and the staining becomes more brown and no longer fluoresces under UV light.
*
Porphyria
Porphyria is a group of liver disorders in which substances called porphyrins build up in the body, negatively affecting the skin or nervous system. The types that affect the nervous system are also known as acute porphyria, as symptoms are ra ...
: A rare metabolic disorder in which the body fails to adequately metabolise
porphyrin
Porphyrins ( ) are a group of heterocyclic macrocycle organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (=CH−). The parent of porphyrin is porphine, a rare chemical com ...
s, which leads to accumulation or excretion of porphyrins into teeth. The excretion of porphyrins produces purple-red pigments in teeth.
*
Hemolytic disease of the newborn
Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis foetalis, is an alloimmune condition that develops in a fetus at or around birth, when the IgG molecules (one of the five ...
: This disease occurs when a newborn's red blood cells are being attacked by
antibodies
An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
from the mother caused by an incompatibility between the mother and baby's blood. This condition can produce green staining of teeth due to jaundice, which is an inability to excrete bilirubin properly.
*
Root resorption
Resorption of the root of the tooth, or root resorption, is the progressive loss of dentin and cementum by the action of odontoclasts. Root resorption is a normal physiological process that occurs in the exfoliation of the primary dentition. Howeve ...
: Root resorption is clinically asymptomatic, however can produce a pink appearance at the amelocemental junction.
*
Alkaptonuria
Alkaptonuria is a rare inherited genetic disease which is caused by a mutation in the ''HGD'' gene for the enzyme homogentisate 1,2-dioxygenase (); if a person inherits an abnormal copy from both parents (it is a recessive condition), the body ac ...
: Metabolic disorder which promotes the accumulation of
homogentisic acid
Homogentisic acid (2,5-dihydroxyphenylacetic acid) is a phenolic acid usually found in ''Arbutus unedo'' (strawberry-tree) honey. It is also present in the bacterial plant pathogen ''Xanthomonas campestris'' pv. ''phaseoli'' as well as in the ye ...
in the body and may cause brown colour pigmentation in the teeth, gums, and
buccal mucosa
The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed '' lamina propria''. The oral cavity has sometimes been des ...
.
Methods
Prior to proceeding to tooth whitening alternatives, it is advised that the patient comes into the dental office to have a comprehensive oral examination that consists of a full medical, dental, and social history. This will allow the clinician to see if there is any treatment that needs to be done such as restorations to remove cavities, and to assess whether or not the patient will be a good candidate to have the whitening done. The clinician would then debride (clean) the tooth surface with an
ultrasonic scaler
Scaling and root planing, also known as conventional periodontal therapy, non-surgical periodontal therapy or deep cleaning, is a procedure involving removal of dental plaque and Calculus (dental), calculus (scaling or Debridement (dental), debri ...
, hand instruments, and potentially a prophy paste to remove extrinsic stains as mentioned above. This will allow a clean surface for maximum benefits of whichever tooth whitening method the patient chooses. Below will discuss the various types of tooth whitening methods including both internal application of bleaching and external application through the use of bleaching agents.
In-office
Before the treatment, the clinician should examine the patient: taking a health and dental history (including
allergies
Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...
and sensitivities), observe hard and soft tissues, placement and conditions of restorations, and sometimes
x-rays
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 Picometre, picometers to 10 Nanometre, nanometers, corresponding to frequency, ...
to determine the nature and depth of possible irregularities. If this is not completed prior to the whitening agents being applied to the tooth surface, excessive sensitivity and other complications may occur.
The whitening shade guides are used to measure tooth colour. These shades determine the effectiveness of the whitening procedure, which may vary from two to seven shades. These shades may be reached after a single in office appointment, or may take longer, depending on the individual. The effects of bleaching can last for several months, but may vary depending on the lifestyle of the patient. Consuming tooth staining foods or drinks that have a strong colour may compromise effectiveness of the treatment. These include food and drinks containing tannins such as; coffee, tea, red wines, and curry.
In-office bleaching procedures generally use a light-cured protective layer that is carefully painted on the
gums
The gums or gingiva (plural: ''gingivae'') consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health.
Structure
The gums are part of the soft tissue linin ...
and
papilla
Papilla (Latin, 'nipple') or papillae may refer to:
In animals
* Papilla (fish anatomy), in the mouth of fish
* Basilar papilla, a sensory organ of lizards, amphibians and fish
* Dental papilla, in a developing tooth
* Dermal papillae, part of ...
(the tips of the gums between the teeth) to reduce the risk of
chemical burn
A chemical burn occurs when living tissue is exposed to a corrosive substance (such as a strong acid, base or oxidizer) or a cytotoxic agent (such as mustard gas, lewisite or arsine). Chemical burns follow standard burn classification and may ca ...
s to the
soft tissue
Soft tissue is all the tissue in the body that is not hardened by the processes of ossification or calcification such as bones and teeth. Soft tissue connects, surrounds or supports internal organs and bones, and includes muscle, tendons, ligam ...
s. The bleaching agent is either
carbamide peroxide
Hydrogen peroxide - urea (also called Hyperol, artizone, urea hydrogen peroxide, and UHP) is a solid composed of equal amounts of hydrogen peroxide and urea. This compound is a white crystalline solid which dissolves in water to give free hydroge ...
, which breaks down in the mouth to form
hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...
, or hydrogen peroxide itself. The bleaching gel typically contains between 10% and 44% carbamide peroxide, which is roughly equivalent to a 3% to 16% hydrogen peroxide concentration. The legal percentage of hydrogen peroxide allowed to be given is 0.1–6%. Bleaching agents are only allowed to be given by dental practitioners,
dental therapist A dental therapist is a member of the dental team who provides preventive and restorative dental care for children and adults. The precise role varies and is dependent on the therapist's education and the various dental regulations and guidelines o ...
s, and
dental hygienist
A dental hygienist or oral hygienist is a licensed dental professional, registered with a dental association or regulatory body within their country of practice. Prior to completing clinical and written board examinations, registered dental hygien ...
s.
Bleaching is least effective when the original tooth color is grayish and may require custom bleaching trays. Bleaching is most effective with yellow discolored teeth. If heavy staining or
tetracycline
Tetracycline, sold under various brand names, is an oral antibiotic in the tetracyclines family of medications, used to treat a number of infections, including Acne vulgaris, acne, cholera, brucellosis, plague (disease), plague, malaria, and sy ...
damage is present on a patient's teeth, and whitening is ineffective (tetracycline staining may require prolonged bleaching, as it takes longer for the bleach to reach the dentine layer), there are other methods of masking the stain. Bonding, which also masks tooth stains, is when a thin coating of composite material is applied to the front of a person's teeth and then cured with a blue light. A
veneer
Veneer may refer to:
Materials
* Veneer (dentistry), a cosmetic treatment for teeth
* Masonry veneer, a thin facing layer of brick
* Stone veneer, a thin facing layer of stone
* Wood veneer, a thin facing layer of wood
Arts and entertainment
* ' ...
can also mask tooth discoloration.
In-chair whitening is faster and more effective in comparison to the take-home bleaching options. Some clinicians also make custom bleaching trays, which can take up to a week to create. After the whitening treatment is completed, the patient is able to use these trays for maintenance of their bleaching with at-home kits or for use with desensitising products.
Light-accelerated bleaching
Power or light-accelerated bleaching uses light energy which is intended to accelerate the process of bleaching in a dental office. Different types of energy can be used in this procedure, with the most common being
halogen
The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group is ...
,
LED
A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...
, or plasma arc. Use of light during bleaching increases the risk of tooth sensitivity and may not be any more effective than bleaching without light when high concentrations of hydrogen peroxide are used. A 2015 study showed that the use of a light activator does not improve bleaching, has no measurable effect, and rather is likely to increase the temperature of the associated tissues, resulting in damage.
The ideal source of energy should be high energy to excite the peroxide molecules without overheating the pulp of the tooth. Lights are typically within the blue light spectrum as this has been found to contain the most effective wavelengths for initiating the hydrogen peroxide reaction. A power bleaching treatment typically involves isolation of soft tissue with a resin-based, light-curable barrier, application of a professional dental-grade hydrogen peroxide whitening gel (25–38% hydrogen peroxide), and exposure to the light source for 6–15 minutes. Recent technical advances have minimized heat and UV emissions, allowing for a shorter patient preparation procedure.
For any whitening treatments, it is recommended that a comprehensive examination of the patient is done including the use of radiographs to aid in the diagnosis of the current condition of the mouth, including any allergies that may be present. The patient will need to have a healthy mouth and free of periodontal disease or cavities and to have had a debridement/clean done to remove any tartar or plaque build up.
It is recommended to avoid smoking, drinking red wine, eating or drinking any deeply coloured foods after this as the teeth may stain considerably straight after treatment.
Nanoparticle catalysts for reduced hydrogen peroxide concentration
A recent addition to the field is new light-accelerated bleaching agents containing lower concentrations of hydrogen peroxide with a titanium oxide
nanoparticle
A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 1 ...
-based catalyst. Reduced concentrations of hydrogen peroxide cause lower incidences of tooth hypersensitivity. The nanoparticles act as photocatalysts, and their size prevents them from diffusing deeply into the tooth. When exposed to light, the catalysts produce a rapid, localized breakdown of hydrogen peroxide into highly reactive radicals. Due to the extremely short lifetimes of the free radicals, they are able to produce bleaching effects similar to much higher concentration bleaching agents within the outer layers of the teeth where the nanoparticle catalysts are located. This provides effective tooth whitening while reducing the required concentration of hydrogen peroxide and other reactive byproducts at the tooth pulp.
Internal bleaching
Internal bleaching is a process which occurs after a tooth has been endodontically treated. This means that the tooth will have had the nerve of the tooth extirpated or removed through a root canal treatment at the dentist or by a specialist
endodontist
Endodontics (from the Greek roots ''endo-'' "inside" and ''odont-'' "tooth") is the dental specialty concerned with the study and treatment of the dental pulp.
Overview
Endodontics encompasses the study (practice) of the basic and clinical ...
. Internal bleaching is often sought after in teeth which have been endodontically treated as tooth discolouration becomes a problem due to the lack of nerve supply to that tooth. It is common to have this internal bleaching done on an anterior tooth (a front tooth that you can see when smiling and talking). A way around this is by sealing off the bleaching agent inside the tooth itself and replacing it every few weeks until the desired shade has been achieved. The amount of time between appointments varies from patient to patient and with operator preference until the desired shade has been achieved. Even though this is a great option, the disadvantage of this treatment is a risk of internal root resorption of the tooth that is being internally bleached. This may not occur in every patient or every tooth, and its occurrence is difficult to determine prior to completing the treatment.
At home
At home tooth whitening products are available from dentists or '
over the counter
Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid prescr ...
' (OTC). At home whitening methods include over-the-counter strips and gels, whitening rinses, whitening toothpastes, and tray-based tooth whiteners. OTC products can be used for milder cases of tooth staining. Home-based bleaching (following manufacturer's instructions) results in less tooth sensitivity than in-office bleaching.
Strips and gels
The plastic whitening strips contain a thin layer of peroxide gel and are shaped to fit the buccal/labial surfaces of teeth. Many different types of whitening strips are available on the market, after being introduced in the late 1980s. Specific whitening strip products have their own set of instructions however the strips are typically applied twice daily for 30 minutes for 14 days. In several days, tooth colour can lighten by 1 or 2 shades. The tooth whitening endpoint does depend on the frequency of use and ingredients of the product.
Whitening gels are applied onto the tooth surface with a small brush. The gels contain peroxide and are recommended to be applied twice a day for 14 days. The tooth whitening endpoint like that of the whitening strips.
Rinses
Whitening rinses work by reaction of the oxygen sources such as hydrogen peroxide within the rinse and the chromogens on or within the tooth. It is recommended to use twice a day, rinsing for one minute. To see an improvement in shade colour, it can take up to three months.
Toothpastes
Whitening toothpastes differ from regular toothpastes in that they contain higher amounts of abrasives and detergents to be more effective at removing tougher stains. Some whitening toothpastes contain low concentrations of carbamide peroxide or hydrogen peroxide which help lighten tooth colour however they do not contain bleach (
sodium hypochlorite
Sodium hypochlorite (commonly known in a dilute solution as bleach) is an Inorganic chemistry, inorganic chemical compound with the chemical formula, formula NaOCl (or NaClO), comprising a sodium cation () and a hypochlorite anion (or ). It may ...
). With continuity of use over time, tooth colour can lighten by one or two shades.
Tray-based
Tray-based tooth whitening is achieved by wearing a fitted tray containing carbamide peroxide bleaching gel overnight or for two to four hours a day. If manufacturer's instructions are followed, tooth whitening can occur within three days and lighten teeth by one or two shades. This type of tooth whitening is available over-the-counter and professionally from an oral health professional.
Baking soda
Baking soda is a safe, low abrasive, and effective stain removal and tooth whitening toothpaste. Tooth whitening toothpaste that have excessive abrasivity are harmful to dental tissue, therefore baking soda is a desirable alternative. To date, clinical studies on baking soda report that there have been no reported adverse effects. It also contains acid-buffering components that makes baking soda biologically antibacterial at high concentrations and capable of preventing growth of ''Streptococcus mutans.'' Baking soda might be useful for cavities-prone patients, as well as those who wish to have whiter teeth.
Pens
Whitening pens are a convenient way to touch up any dental surface. The plastic, convenient, tube contains a bleaching gel that can be easily applied in hard-to-reach spots. In order to work, the gel needs to stay on the tooth surface for around 20-30 minutes.
Indications
Tooth whitening may be undertaken for a variety of reasons, but whitening may also be recommended to some individuals by dental professionals.
* Intrinsic tooth staining
* Aesthetics
* Dental fluorosis
* Endodontic treatment (internal bleaching)
* Tetracycline staining
Contraindications
Some groups are advised to carry out tooth whitening with caution as they may be at higher risk of adverse effects.
* Patients with unrealistic expectations
* Allergy to peroxide
* Pre-existing sensitive teeth
* Cracks or exposed dentine
* Enamel development defects
*
Acid erosion
Acid erosion is a type of tooth wear. It is defined as the irreversible loss of tooth structure due to chemical dissolution by acids not of bacterial origin. Dental erosion is the most common chronic condition of children ages 5–17, altho ...
* Receding gums (
gingival recession
Gingival recession, also known as receding gums, is the exposure in the roots of the teeth caused by a loss of gum tissue and/or retraction of the gingival margin from the crown of the teeth.fillings and other restorative materials. It does not affect
porcelain
Porcelain () is a ceramic material made by heating substances, generally including materials such as kaolinite, in a kiln to temperatures between . The strength and translucence of porcelain, relative to other types of pottery, arises mainl ...
, other
ceramic
A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...
s, or dental gold. However, it can slightly affect restorations made with composite materials, cements and dental amalgams. Tooth whitening will not restore color of fillings,
porcelain
Porcelain () is a ceramic material made by heating substances, generally including materials such as kaolinite, in a kiln to temperatures between . The strength and translucence of porcelain, relative to other types of pottery, arises mainl ...
, and other
ceramic
A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...
s when they become stained by foods, drinks, and smoking, as these products are only effective on natural tooth structure. As such, a shade mismatch may be created as the natural tooth surfaces increase in whiteness and the restorations stay the same shade. Whitening agents do not work where bonding has been used and neither is it effective on tooth-colored filling materials. Other options to deal with such cases are the
porcelain
Porcelain () is a ceramic material made by heating substances, generally including materials such as kaolinite, in a kiln to temperatures between . The strength and translucence of porcelain, relative to other types of pottery, arises mainl ...
veneers or
dental bonding
Adhesive dentistry is a branch of dentistry which deals with adhesion or bonding to the natural substance of teeth, enamel and dentin. It studies the nature and strength of adhesion to dental hard tissues, properties of adhesive materials, cause ...
.
* Individuals with poor oral hygiene
Risks
Some of the common side effects involved in teeth whitening are increased sensitivity of the teeth, gum irritation, and extrinsic teeth discolouration.
Hypersensitivity
The use of bleach with extremely low pH levels in the tooth whitening procedure may lead to hypersensitive teeth, as it causes the
dentinal tubules
Bone canaliculi are microscopic canals between the lacunae of ossified bone. The radiating processes of the osteocytes (called filopodia) project into these canals. These cytoplasmic processes are joined together by gap junctions. Osteocytes do ...
to open. Exposure to cold, hot, or sweet stimuli may further exacerbate the intensity of the hypersensitive response. Amongst those who receive in-office whitening treatment, between 67–78% of the individuals experience sensitivity after the procedure where hydrogen peroxide and heat is utilised. Although it varies from person to person, sensitivity after whitening treatment can last up to 4–39 days.
Potassium nitrate
Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitrat ...
and
sodium fluoride
Sodium fluoride (NaF) is an inorganic compound with the formula . It is used in trace amounts in the fluoridation of drinking water, in toothpaste, in metallurgy, and as a flux. It is a colorless or white solid that is readily soluble in water. I ...
in toothpastes are used to ease discomfort following bleaching, however, there is no evidence to suggest that this is a permanent method to eradicate the issue of hypersensitivity.
Irritation of mucous membranes
Hydrogen peroxide is an irritant and
cytotoxic
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'').
Cell physiology
Treating cells ...
. Hydrogen peroxide with concentrations of 10% or higher can cause tissue damage, be corrosive to mucous membranes and cause burning sensation to the skin. Chemical burns can commonly occur whilst bleaching, irritation and discolouration of the mucous membranes may occur if a high concentration of oxidising agent comes in to contact with unprotected tissue. Poorly fitting bleaching trays are amongst the most common reasons for chemical burns. The temporary burning induced by whitening treatments can be reduced by using custom-made plastic trays or nightguards provided by the dental professional. This prevents the leakage of solution onto the surrounding
mucosa
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
.
Uneven results
Uneven results are quite common after bleaching. Consuming less foods and drinks that cause surface staining of teeth can contribute to attaining a good result from tooth whitening.
Return to original pre-treatment shade
Nearly half the initial change in colour provided by an intensive in-office treatment (i.e., one hour treatment in a dentist's chair) may be lost in seven days. Rebound is experienced when a large proportion of the tooth whitening has come from tooth dehydration (also a significant factor in causing sensitivity). As the tooth rehydrates, tooth colour "rebounds", back toward where it started.
Over-bleaching
Over-bleaching, more often known as the "bleached effect", occurs among treatments that promise a large change over a short period of time e.g., hours. Over-bleaching can emit a translucent and brittle appearance.
Damage to enamel
Teeth enamel can have an adverse negative effect by whitening treatment. Evidence from studies show that carbamide peroxide present in whitening gels can damage the enamel surface. Although this effect is not as damaging as phosphoric acid etch, the increased irregularity of the teeth surface makes the teeth more susceptible to extrinsic staining, thus having an increased detrimental effect on the aesthetics. The increased porosity and changes in surface roughness may have an impact on the formation of supra- and subgingival
plaque
Plaque may refer to:
Commemorations or awards
* Commemorative plaque, a plate or tablet fixed to a wall to mark an event, person, etc.
* Memorial Plaque (medallion), issued to next-of-kin of dead British military personnel after World War I
* Pla ...
, thus increasing the adhesion of bacterial species such as ''
Streptococcus mutans
''Streptococcus mutans'' is a facultatively anaerobic, gram-positive coccus (round bacterium) commonly found in the human oral cavity and is a significant contributor to tooth decay.
It is part of the " streptococci" (plural, non-italic lowercase ...
and
Streptococcus sobrinus
''Streptococcus sobrinus'' is a Gram-positive, catalase-negative, non-motile, and Anaerobic organism, anaerobic member of the genus ''Streptococcus''.
Pathology
''Streptococcus sobrinus'' in conjunction with the closely related species ''Strept ...
,'' significant contributors to
dental cavities
Dental may refer to:
* Dental consonant, in phonetics
* Dental Records, an independent UK record label
* Dentistry, oral medicine
* Teeth
See also
*
* Dental care (disambiguation)
* Dentist (disambiguation)
* Tooth (disambiguation)
A tooth (pl ...
.
Dental restoration
Dental restoration, dental fillings, or simply fillings are treatments used to restore the function, integrity, and morphology of missing tooth structure resulting from caries or external trauma as well as to the replacement of such structure sup ...
s are susceptible to unacceptable colour change even when using the home-based systems.
Weakened dentine
Intracoronal bleaching is a tooth whitening method that uses 30% more hydrogen peroxide. Such tooth whitening methods can weaken the mechanical properties of dentine and could potentially lead to severe tooth sensitivity.
Effects on existing restorations
Dental restoration
Dental restoration, dental fillings, or simply fillings are treatments used to restore the function, integrity, and morphology of missing tooth structure resulting from caries or external trauma as well as to the replacement of such structure sup ...
s are susceptible to unacceptable colour change even when using the home-based systems.
Ceramic
crowns
A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...
– aggressive bleaching can chemically react with ceramic crowns and reduce their stability.
Dental
amalgam
Amalgam most commonly refers to:
* Amalgam (chemistry), mercury alloy
* Amalgam (dentistry), material of silver tooth fillings
** Bonded amalgam, used in dentistry
Amalgam may also refer to:
* Amalgam Comics, a publisher
* Amalgam Digital
...
– exposure to
carbamide peroxide
Hydrogen peroxide - urea (also called Hyperol, artizone, urea hydrogen peroxide, and UHP) is a solid composed of equal amounts of hydrogen peroxide and urea. This compound is a white crystalline solid which dissolves in water to give free hydroge ...
solutions increase
mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
release for one to two days. The release of amalgam components is said to be due to active
oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
. This increase in amalgam mercury release is proportional to the concentration of carbamide peroxide.Resin composite – bond strength between enamel and resin based fillings become weakened. Many studies have found that 10-16% carbamide peroxide tooth bleaching gels (containing approximately 3.6-5.76% hydrogen peroxide) leads to an increase in the surface roughness and porosity of composite resins. However, the saliva may exert a protective effect. In addition, changes in the reflectance of the composite have been analysed following whitening with high concentration (30-35%) hydrogen peroxide. This suggests that tooth whitening negatively impacts composite resin restorations.Glass ionomer and other cements – studies suggest that solubility of these materials may increase.
Bleachorexia
Bleachorexia is the term that is used to describe an individual that develops an unhealthy obsession with teeth whitening. This condition is similar to
body dysmorphic disorder
Body dysmorphic disorder (BDD), occasionally still called dysmorphophobia, is a mental disorder characterized by the obsessive idea that some aspect of one's own body part or appearance is severely flawed and therefore warrants exceptional meas ...
. The characteristics of bleachorexia are the continuous use of whitening products even though the teeth cannot possibly become whiter, despite the provision of repeated treatment. A person with bleachorexia will continually seek out for different whitening products, hence, it is recommended that a target shade is agreed upon before starting the treatment procedure to help with this problem.
Home teeth whitening risks
The use of personalised home whitening trays is a patient administered therapy that is prescribed and dispensed by a dentist. Patients need to actively participate in their treatment and follow the guidelines given by the dentist accurately. Erratic or inaccurate use of the bleaching trays could cause harm to the patient such as blistering or sensitivity of the teeth and the surrounding soft tissue. Inconsistent use of the bleaching trays can lead to the slowing and irregularity of the whitening process. Some patients with a substantial
gag reflex The pharyngeal reflex or gag reflex is a reflex muscular contraction of the back of the throat, evoked by touching the roof of the mouth, the back of the tongue, the area around the tonsils, the uvula, and the back of the throat. It, along with othe ...
may not be able to tolerate the trays and would need to consider other methods of teeth whitening.
Other risks
Evidence suggests that hydrogen peroxide might act as a tumour promoter. Although cervical root resorption is more evidently observed in thermocatalytic bleaching methods, intracoronal internal bleaching may also lead to tooth root resorption. Moreover, severe damage to intracoronal dentine and tooth crown fracture can occur due to this bleaching method.
However, the International Agency of Research on Cancer (IARC) has concluded that there is insufficient evidence to prove that hydrogen peroxide is a
carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...
to humans. Recently, the genotoxic potential of hydrogen peroxide was evaluated. The results indicated that the oral health products that contain or release hydrogen peroxide up to 3.6% will not increase the cancerous risk of an individual, hence, it is safe to use in moderation.
Maintenance
Despite achieving the results of treatment, stains can return within an initial couple of months of treatment. Various methods may be employed to prolong the treatment results, such as:
* Brush or flush out mouth with water after eating and drinking
* Floss to remove plaque and biofilms between the teeth
* Take special care during the first 2 days – the first 24–48 hours after the whitening procedure is seen as the most crucial period in which you must protect for your teeth the most. Hence, it is vital that non-staining drinks or foods are eaten during this time as enamel is prone to adhere to stains.
* Drink fluids that may cause staining through a straw
* Depending on the method used to whiten the teeth, re-treatment every six months or after a year may be required. If an individual is a smoker or they consume beverages with the capacity to stain, regular re-treatments would be required.
History
Teeth whitening remedies have been present since ancient times. Despite seeming absurd, some methods were somewhat effective in their results.
Ancient Roman dentists believed in using
urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra.
Cel ...
with
goat milk
Goat milk is the milk of domestic goats. Goats produce about 2% of the world's total annual milk supply. Some goats are bred specifically for milk. Goat milk naturally has small, well-emulsified fat globules, which means the cream will stay in ...
to make their teeth look whiter. Pearly white teeth symbolized beauty and marked wealth. In the Auyrveda medicine system, oil pulling was used as an oral therapy. For this process today, swish coconut or olive oil in your mouth for up to 20 minutes each day. In the late 17th century, many people reached out to barbers, who used a file to file down the teeth before applying an acid that would, in fact, whiten the teeth. Although the procedure was successful, the teeth would become completely eroded and more prone to becoming decayed.
Guy de Chauliac
Guy de Chauliac (), also called Guido or Guigo de Cauliaco ( 1300 – 25 July 1368), was a French physician and surgeon who wrote a lengthy and influential treatise on surgery in Latin, titled '' Chirurgia Magna''. It was translated into many othe ...
suggested the following to whiten the teeth: "Clean the teeth gently with a mixture of honey and burnt salt to which some vinegar has been added." In 1877,
oxalic acid
Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early inve ...
was proposed for whitening, followed by
calcium hypochlorite
Calcium hypochlorite is an inorganic compound with formula Ca(OCl)2. It is the main active ingredient of commercial products called bleaching powder, chlorine powder, or chlorinated lime, used for water treatment and as a bleaching agent. Thi ...
.
In the late 1920s, mouthwash containing pyrozone (ether peroxide) was found to reduce cavities while providing a whiter appearance to the teeth. By 1940s and 1950s, ether and hydrogen peroxide gels were used to whiten vital teeth, whereas non-vital teeth were whitened using pyrozone and sodium perborate.
In the late 1960s, Dr William Klusmeier, an Orthodontist from Fort Smith, Arkansas, introduced the custom tray bleaching. However, it was not until 1989 that Haywood and Heymann published an article in support of this method. Carbamide peroxide with a shelf life of one to two years, as opposed to hydrogen peroxide with a shelf life one to two months, was seen as a more stable agent for whitening teeth.
Society and culture
Teeth whitening has become the most promoted and mentioned methodology in
cosmetic dentistry Cosmetic dentistry is generally used to refer to any dental work that improves the appearance (though not necessarily the functionality) of teeth, gums and/or bite. It primarily focuses on improvement in dental aesthetics in color, position, shape, ...
. In excess of 100 million Americans brighten their teeth using different methods; spending $15 billion in 2010.Krupp, Charla. (2008). ''How Not To Look Old.'' New York: Springboard Press, p.95. The US
Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
only endorses gels that are under 6% hydrogen peroxide or 16% or less of carbamide peroxide. The
Scientific Committee on Consumer Safety
The Scientific Committee on Consumer Safety (SCCS) is one of the independent scientific committees managed by the Directorate-General for Health and Consumer Protection of the European Commission, which provide scientific advice to the commission ...
of the EU consider gels containing higher fixations can be dangerous.
As per
European Council
The European Council (informally EUCO) is a collegiate body that defines the overall political direction and priorities of the European Union. It is composed of the heads of state or government of the EU member states, the President of the E ...
guidelines, only a certified dental professional can lawfully give tooth whitening products utilizing 0.1–6% hydrogen peroxide, provided the patient is 18 years of age or older. In 2010, the UK
General Dental Council
The General Dental Council (GDC) is an organisation which regulates dental professionals in the United Kingdom. It keeps an up-to-date register of all qualified dentists and other dental care professionals such as: dental hygienists, dental ther ...
became concerned of the "risk to patient safety from poor quality tooth whitening being carried out by untrained or poorly trained staff." A public attitudes survey, conducted by the GDC, showed that 83% of people support "policies of regulating tooth whitening to protect patient safety and prosecuting illegal practice." A group of dental professionals and associations called The Tooth Whitening Information Group (TWIG) was founded to advance protected and beneficial tooth whitening information and assistance to the general population. Reports can be made to the TWIG through their website with respect to any individual giving unlawful tooth whitening services, or if an individual has personally undergone treatment done by a non-dental professional.
In Brazil, all whitening items are classed as cosmetics (Degree II). There are worries that this will bring about increasing abuse of whitening products and thus there have been calls for reanalysis.
According to research, tooth whitening can produce positive changes in young participants’ Oral Health Related Quality of Life (OHRQoL) in aesthetic areas such as smiling, laughing, and showing teeth without embarrassment. However, its main side-effect, tooth sensitivity, does negatively affect quality of life.
See also
*
Gum depigmentation
Gum depigmentation, also known as gum bleaching, is a procedure used in cosmetic dentistry to lighten or remove black spots or patches on the gums consisting of melanin. Melanin in skin is very common in inhabitants in many parts of the world due ...
*
Oral Hygiene
Oral hygiene is the practice of keeping one's mouth clean and free of disease and other problems (e.g. bad breath) by regular brushing of the teeth (dental hygiene) and cleaning between the teeth. It is important that oral hygiene be carried out ...