Tooth discoloration

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Tooth discoloration
Other namesTooth staining
Tired teeth.jpg
Specialty Dentistry

Tooth discoloration is abnormal tooth color, hue or translucency. [1] External discoloration is accumulation of stains on the tooth surface. Internal discoloration is due to absorption of pigment particles into tooth structure. [2] [3] Sometimes there are several different co-existent factors responsible for discoloration. [4]


Normal tooth shade

Cross-sectional diagram of a molar tooth. 1: crown, 2: root, 3: enamel, 4: dentin and dentin tubules, 5: pulp chamber, 6: blood vessels and nerve within root canal, 7: periodontal ligament, 8: apex and periapical region, 9: alveolar bone Cross sections of teeth labels.png
Cross-sectional diagram of a molar tooth. 1: crown, 2: root, 3: enamel, 4: dentin and dentin tubules, 5: pulp chamber, 6: blood vessels and nerve within root canal, 7: periodontal ligament, 8: apex and periapical region, 9: alveolar bone
VITA classical A1-D4 shade guide arranged according to value VITA shade guide.jpg
VITA classical A1-D4 shade guide arranged according to value
VITA classical A1-D4 shade guide arranged according to chroma; A: red-brown, B: red-yellow, C: grey, D: red-grey VITA shade guide2.jpg
VITA classical A1-D4 shade guide arranged according to chroma; A: red-brown, B: red-yellow, C: grey, D: red-grey

The appearance and perception of a tooth is the result of a complex interaction of factors such as lighting conditions, translucency, opacity, light scattering, gloss and the human eye and brain. [5] Of these, the intrinsic pigmentation of a tooth is the most influential, [4] which in turn is determined by genetic and natural factors. [6] Light hitting a tooth undergoes reflection, absorption and transmission by varying degrees in each tissue layer of the tooth substance. [4] Reflected light detected by the human eye determines the perceived appearance of a tooth. [4]

Teeth have a thin enamel layer on the outer surface. The enamel layer is whiter and semitransparent, and contributes blue, pink green tints to the tooth color. [6] The underlying dentin layer is darker than enamel, yellow-brown in color, and less transparent. [6] Dentin forms the bulk of the tooth substance, [7] and contributes most to the overall tooth color. [6] At the core of the tooth is soft connective tissue termed the dental pulp. [8] The pulp is pink/red due to its vascularity, but is rarely visible through the overlying enamel and dentin unless the thickness of these layers is reduced by tooth wear (or rarely internal resorption).

Public opinion of what is normal tooth shade tends to be distorted. Portrayals of cosmetically enhanced teeth are common in the media. In one report, the most common tooth shade in the general population ranged from A1 to A3 on the VITA classical A1-D4 shade guide. [9]

Tooth color varies according to race, gender and geographic region. [4] Females generally have slightly whiter teeth than males, partly because females' teeth are smaller, and therefore there is less bulk of dentin, partially visible through the enamel layer. For the same reason, larger teeth such as the molars and the canine (cuspid) teeth tend to be darker. Baby teeth (deciduous teeth) are generally whiter than the adult teeth that follow, again due to differences in the ratio of enamel to dentin.


Extrinsic discoloration

The stained teeth of a regular betel chewer in Burma Betel.jpg
The stained teeth of a regular betel chewer in Burma

Extrinsic discolorations are common and have many different causes. [10] The same range of factors are capable of staining the surface of restorations (e.g., composite fillings, porcelain crowns). [10] Some extrinsic discolorations that are allowed to remain for a long time may become intrinsic. [11]

Intrinsic discoloration

Causes of intrinsic discoloration generally fall into those that occur during tooth development and those acquired later in life. The known causes of intrinsic staining are listed below, however some causes are unknown. [17]

Dental caries

Dental caries (tooth decay) begins as an opaque white spot on the surface of the enamel. As demineralization progresses, the various lesion eventually cavitates and the underlying brown color becomes visible. [13]


Mild fluorosis: mostly on the upper right central incisor MildFluorosis02-24-09.jpg
Mild fluorosis: mostly on the upper right central incisor
Severe fluorosis: mottled enamel of an individual from a region with high levels of naturally occurring fluoride 4724507933 07ac954c27 bFluorose.jpg
Severe fluorosis: mottled enamel of an individual from a region with high levels of naturally occurring fluoride

Fluorosis may occur when there is chronic and excessive exposure to fluoride during the years of tooth development. [3] [10] Fluoride is a naturally occurring mineral in water, although some regions have higher levels than others, and in some areas fluoride is added to water supplies in low levels to help prevent tooth decay. Exposure can also occur via bottled water and fluoride toothpaste. In its mildest form, fluorosis appears as small opaque white flecks on the enamel surface. [18] More severe cases show severely hypoplastic patches of enamel, which are also prone to accumulation of surface stains. [18] Chronological, fine white bands of fluorosis may be seen that correspond to the times of high exposure to fluoride. [18]


Dental trauma may result in discolorations. [13] Following luxation injuries red discoloration may develop almost instantly. This is due to severance of the venous microcirculation to a tooth, while the arteries continue to supply blood to the pulp. The blood is then decomposed gradually and a blue-brown discoloration develops. [2]

Teeth may turn grey following trauma-induced pulp necrosis (death of the pulp). [2] This discoloration typically develops weeks or months after the injury and is caused by incorporation of pigments released during the breakdown of the pulpal tissue and blood into the dentin. [2]

Yellow discoloration may occur following pulp canal obliteration, i.e., the sealing up of the pulp. [2] Trauma to a developing adult tooth (e.g., intrusion of a baby tooth into the bone) may affect the enamel layer of the adult tooth. [2] This becomes apparent when the adult tooth erupts into the mouth. [2]

Pulp necrosis

Teeth die mainly as a result of extensive tooth decay, however this may also occur following dental trauma or heavy drilling down of the tooth during tooth preparation prior to restoration.

Internal resorption

Internal resorption of the left maxillary lateral incisor (right in photograph), giving rise to the appearance termed "Pink tooth of Mummery" Mummery.jpg
Internal resorption of the left maxillary lateral incisor (right in photograph), giving rise to the appearance termed "Pink tooth of Mummery"

Internal resorption may sometimes follow dental trauma (although in other cases it appears unrelated). This is where the dentin is resorbed and replaced instead by hyperplastic, vascular pulp tissue. As this process starts to approach the external surface of the tooth, a pink hue of this replacement pulp tissue may become visible through the remaining overlying tooth substance. [19] This appearance is sometimes termed "pink tooth of Mummery". [19]

Root canal treatment

Internal staining is common following root canal treatment, however the exact causes for this are not completely understood. [1] Failure to completely clean out the necrotic soft tissue of the pulp system may cause staining, and certain root canal materials (e.g., gutta percha and root canal sealer cements) can also. [1] Another possible factor is the lack of pulp pressure in dentinal tubules once the pulp is removed, leading to incorporation of dietary stains in dentin. [1]

Amalgam fillings

Amalgam filling: giving overall darker appearance to the tooth Filling.jpg
Amalgam filling: giving overall darker appearance to the tooth

Amalgam fillings often stain the tooth they are placed in. [11] This is most noticeable in very old fillings, as pigment slowly leaches out of the amalgam filling material and its associated corroded surfaces. In addition, metallic fillings cast a shadow that can be visible through the tooth and make it appear darker. [11]

Tetracycline and tetracycline-derivatives

Tetracycline is a broad spectrum antibiotic, [20] and its derivative minocycline is common in the treatment of acne. [21] The drug is able to chelate calcium ions and is incorporated into teeth, cartilage and bone. [20] Ingestion during the years of tooth development causes a yellow-green discoloration of dentin, which is visible through the enamel and fluorescent under ultraviolet light. Later, the tetracycline oxidizes and the staining becomes more brown and no longer fluoresces under UV light. [12] [22] Other drugs derived from tetracycline such as glycylcycline share this side effect.[ medical citation needed ] Because tetracyclines cross the placenta, a child may have tooth staining if the drugs are administered during the mother's pregnancy. [23]

Genetic disorders

Several genetic disorders affect tooth development (odontogenesis), and lead to abnormal tooth appearance and structure. Enamel hypoplasia and enamel hypocalcification are examples of defective enamel that potentially gives a discolored appearance to the tooth. Teeth affected in this way are also usually more susceptible to further staining acquired throughout life.

Amelogenesis imperfecta is a rare condition that affects the formation of enamel (amelogenesis). The enamel is fragile, the teeth appear yellow or brown, and surface stains build up more readily. [1]

Dentinogenesis imperfecta is a defect of dentin formation, and the teeth may be discolored yellow-brown, deep amber or blue-grey with increased translucency. [1] Dentinal dysplasia is another disorder of dentin.

Congenital erythropoietic porphyria (Gunther disease) is a rare congenital form of porphyria, and may be associated with red or brown discolored teeth. [1] [12]

Hyperbilirubinemia during the years of tooth formation may make bilirubin incorporate into the dental hard tissues, causing yellow-green or blue-green discoloration. [1] One such condition is hemolytic disease of the newborn (erythroblastosis fetalis). [12]

Thalassemia and sickle cell anemia may be associated with blue, green or brown tooth discoloration. [1]

A high proportion of children with cystic fibrosis have discolored teeth. [23] This is possibly the result of exposure to tetracycline during odontogenesis, [23] however cystic fibrosis transmembrane regulator has also been demonstrated to be involved in enamel formation, suggesting that the disease has some influence on tooth discoloration regardless of exposure to tetracyclines.


Intrinsic discoloration tends to accompany aging. Throughout life deposition of secondary dentin occurs along the internal walls of the pulp chamber. Secondary dentin is darker and more opaque than primary dentin. This gives the dentin an overall darker appearance. [11] At the same time, the enamel layer is gradually thinned by tooth wear processes such as attrition and acid erosion, a degree of which is considered normal. [11] Enamel also becomes less porous and phosphate deficient.[ medical citation needed ]


Discoloration of the front teeth is one of the most common reasons people seek dental care. [10] However, many people with teeth of normal shade ask for them to be whitened. [10] Management of tooth discoloration depends on the cause. Most discoloration is harmless and may or may not be of cosmetic concern to the individual. In other cases it may indicate underlying pathology such as pulp necrosis or rarely a systemic disorder.

Most extrinsic discoloration is readily removed by cleaning the teeth, whether with "whitening" (i.e., abrasive) toothpaste at home, or as treatment carried out by a professional (e.g., scaling and/or polishing). To prevent future buildup of extrinsic stains, identification of the cause (e.g., smoking) is required.

Intrinsic discoloration generally requires one of the many types of tooth bleaching. Alternatively the appearance of the tooth can be hidden with dental restorations (e.g., composite fillings, veneers, crowns).

Related Research Articles

Human tooth Calcified whitish structure in humans mouths used to break down food

The human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla or the mandible and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.


Cementum is a specialized calcified substance covering the root of a tooth. The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament.

Tooth enamel

Tooth enamel is one of the four major 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. The other major tissues are dentin, cementum, and dental pulp. It is a very hard, white to off-white, highly mineralised substance that acts as a barrier to protect the tooth but can become susceptible to degradation, especially by acids from food and drink. Calcium hardens the tooth enamel. In rare circumstances enamel fails to form, leaving the underlying dentin exposed on the surface.

Tooth decay Deformation of teeth made by acids from bacteria

Tooth decay, also known as dental caries or cavities, is the breakdown of teeth due to acids made by bacteria. The cavities may be a number of different colors from yellow to black. Symptoms may include pain and difficulty with eating. Complications may include inflammation of the tissue around the tooth, tooth loss and infection or abscess formation.

Dental products are specially fabricated materials, designed for use in dentistry. There are many different types of dental products, and their characteristics vary according to their intended purpose.

Dentin Calcified tissue of the body; one of the four major components of teeth

Dentin or dentine 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 enamel on the crown and cementum on the root and surrounds the entire pulp. By volume, 45% of dentin consists of the mineral hydroxyapatite, 33% is organic material, and 22% is water. Yellow in appearance, it greatly affects the color of a tooth due to the translucency of enamel. Dentin, which is less mineralized and less brittle than enamel, is necessary for the support of enamel. Dentin rates approximately 3 on the Mohs scale of mineral hardness. There are two main characteristics which distinguish dentin from enamel: firstly, dentin forms throughout life; secondly, dentin is sensitive.

Toothache Medical condition of the teeth

Toothache, also known as dental pain, is pain in the teeth or their supporting structures, caused by dental diseases or pain referred to the teeth by non-dental diseases. When severe it may impact sleep, eating, and other daily activities.

Tooth whitening or tooth bleaching is the process of lightening the color of human teeth. 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. The chemical degradation of the chromogens within or on the tooth is termed as bleaching. Hydrogen peroxide is the active ingredient most commonly used in whitening products and is delivered as either hydrogen peroxide or carbamide peroxide. 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 that breaks down to produce unstable free radicals. 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 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.

Abrasion (dental)

Abrasion is the non-carious, mechanical wears of tooth from interaction with objects other than tooth-tooth contact. It most commonly affects the premolars and canines, usually along the cervical margins. Based on clinical surveys, studies have shown that abrasion is the most common but not the sole aetiological factor for development of non-carious cervical lesions (NCCL) and is most frequently caused by incorrect toothbrushing technique.

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 disease of children ages 5–17, although it is only relatively recently that it has been recognised as a dental health problem. There is generally widespread ignorance of the damaging effects of acid erosion; this is particularly the case with erosion due to fruit juices, because they tend to be seen as healthy. Acid erosion begins initially in the enamel, causing it to become thin, and can progress into dentin, giving the tooth a dull yellow appearance and leading to dentin hypersensitivity.

Dental fluorosis

Dental fluorosis is a common disorder, characterized by hypomineralization of tooth enamel caused by ingestion of excessive fluoride during enamel formation.

Human tooth development

Tooth development or odontogenesis is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. For human teeth to have a healthy oral environment, all parts of the tooth must develop during appropriate stages of fetal development. Primary (baby) teeth start to form between the sixth and eighth week of prenatal development, and permanent teeth begin to form in the twentieth week. If teeth do not start to develop at or near these times, they will not develop at all, resulting in hypodontia or anodontia.

Dental papilla

In embryology and prenatal development, the dental papilla is a condensation of ectomesenchymal cells called odontoblasts, seen in histologic sections of a developing tooth. It lies below a cellular aggregation known as the enamel organ. The dental papilla appears after 8–10 weeks intra uteral life. The dental papilla gives rise to the dentin and pulp of a tooth.

Dentinogenesis imperfecta

Dentinogenesis imperfecta (DI) is a genetic disorder of tooth development. This condition is a type of dentin dysplasia that causes teeth to be discolored and translucent giving teeth an opalescent sheen. Although genetic factors are the main contributor for the disease, any environmental or systemic upset that impedes calcification or metabolisation of calcium can also result in anomalous dentine.

Dentin hypersensitivity is dental pain which is sharp in character and of short duration, arising from exposed dentin surfaces in response to stimuli, typically thermal, evaporative, tactile, osmotic, chemical or electrical; and which cannot be ascribed to any other dental disease.

Attrition (dental)

Dental attrition is a type of tooth wear caused by tooth-to-tooth contact, resulting in loss of tooth tissue, usually starting at the incisal or occlusal surfaces. Tooth wear is a physiological process and is commonly seen as a normal part of aging. Advanced and excessive wear and tooth surface loss can be defined as pathological in nature, requiring intervention by a dental practitioner. The pathological wear of the tooth surface can be caused by bruxism, which is clenching and grinding of the teeth. If the attrition is severe, the enamel can be completely worn away leaving underlying dentin exposed, resulting in an increased risk of dental caries and dentin hypersensitivity. It is best to identify pathological attrition at an early stage to prevent unnecessary loss of tooth structure as enamel does not regenerate.

Tooth polishing

Tooth polishing is done to smooth the surfaces of teeth and restorations. The purpose of polishing is to remove extrinsic stains, remove dental plaque accumulation, increase aesthetics and to reduce corrosion of metallic restorations. Tooth polishing has little therapeutic value and is usually done as a cosmetic procedure after debridement and before fluoride application. Common practice is to use a prophy cup—a small motorized rubber cup—along with an abrasive polishing compound.

Remineralisation of teeth

Tooth remineralisation is the natural repair process for non-cavitated tooth lesions, in which calcium, phosphate and sometimes fluoride ions are deposited into crystal voids in demineralised enamel. Remineralisation can contribute towards restoring strength and function within tooth structure.

Hard tissue is tissue which is mineralized and has a firm intercellular matrix. The hard tissues of humans are bone, tooth enamel, dentin, and cementum. The term is in contrast to soft tissue.

Enamel microabrasion is a procedure in cosmetic dentistry used to improve the appearance of the teeth. Like tooth whitening it is used to remove discolorations of the tooth surface but microabrasion is a both a mechanical and chemical procedure.


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