Tooth enamel is the hardest and most highly mineralized substance of the body, and with dentin, cementum, and dental pulp is one of the four major tissues which make up the tooth. Dentin ( BE: dentine) is a calcified tissue of the body and along with enamel, Cementum, and pulp is one of the four Cementum is a specialized calcified substance covering the root of a tooth. The dental pulp is the part in the center of a Tooth made up of living soft tissue and cells called Odontoblasts Anatomy It is the normally visible dental tissue of a tooth and must be supported by underlying dentin. Ninety-six percent of enamel consists of mineral, with water and organic material composing the rest.  The normal color of enamel varies from light yellow to grayish white. At the edges of teeth where there is no dentin underlying the enamel, the color sometimes has a slightly blue tone. Since enamel is semitranslucent, the color of dentin and any restorative dental material underneath the enamel strongly affects the appearance of a tooth. In Optics, transparency (also called pellucidity) is the Material property of allowing Variations in the physical appearance of humans, known as human looks, are believed by Anthropologists to be an important factor in the development of personality and Enamel varies in thickness over the surface of the tooth and is often thickest at the cusp, up to 2. A cusp is an occlusal or incisal eminence on a tooth Canine teeth otherwise known as cuspids, each possess a single cusp while Premolars 5 mm, and thinnest at its border, which is seen clinically as the cementoenamel junction (CEJ). The cementoenamel junction, frequently abbreviated as the CEJ, is an anatomical landmark identified on a Tooth. 
Enamel's primary mineral is hydroxylapatite, which is a crystalline calcium phosphate. Hydroxylapatite, also called hydroxyapatite, is a Mineral. It is a naturally occurring form of calcium Apatite with the formula Ca5(PO43(OH In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating Calcium phosphate is the name given to a family of Minerals containing Calcium Ions (Ca2+ together with orthophosphates (PO43-  The large amount of minerals in enamel accounts not only for its strength but also for its brittleness.  Tooth enamel is the hardest substance in the human body, ranking a 5 on Mohs hardness scale. The Mohs scale of mineral hardness characterizes the scratch resistance of various Minerals through the ability of a harder material to scratch a softer material Dentin, less mineralized and less brittle, 3-4 in hardness, compensates for enamel and is necessary as a support. 
Unlike dentin and bone, enamel does not contain collagen. Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce Collagen is the main Protein of Connective tissue in Animals and the most abundant protein in Mammals making up about 50% of the whole-body protein Instead, it has two unique classes of proteins called amelogenins and enamelins. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Amelogenin is a low-molecular-weight Protein found in developing Tooth enamel, and it belongs to a family of extracellular matrix (ECM proteins Enamelin is a protein found in developing Tooth enamel. About 30 % of developing enamel consists of protein of which enamelins comprise While the role of these proteins is not fully understood, it is believed that they aid in the development of enamel by serving as a framework support, among other functions. 
The basic unit of enamel is called an enamel rod. An Enamel rod is the basic unit of Tooth enamel. The antiquated term is enamel prism.  Measuring 4 μm - 8 μm in diameter an enamel rod, formerly called an enamel prism, is a tightly packed mass of hydroxyapatite crystals in an organized pattern.  In cross section, it is best compared to a keyhole, with the top, or head, oriented toward the crown of the tooth, and the bottom, or tail, oriented toward the root of the tooth.
The arrangement of the crystals within each enamel rod is highly complex. Both ameloblasts (the cells which initiate enamel formation) and Tomes' processes affect the crystals' pattern. Ameloblasts are cells that deposit enamel, the hard outer most layer that forms the chewing surface Tomes' processes are a histologic landmark identified on an Ameloblast. Enamel crystals in the head of the enamel rod are oriented parallel to the long axis of the rod.  When found in the tail of the enamel rod, the crystals' orientation diverges slightly from the long axis. 
The arrangement of enamel rods is understood more clearly than their internal structure. Enamel rods are found in rows along the tooth, and within each row, the long axis of the enamel rod is generally perpendicular to the underlying dentin.  In permanent teeth, the enamel rods near the cementoenamel junction (CEJ) tilt slightly toward the root of the tooth. Understanding enamel orientation is very important in restorative dentistry, because enamel unsupported by underlying dentin is prone to fracture. 
The area around the enamel rod is known as interrod enamel. Interrod enamel is histologically identified on microscopic views of Tooth enamel. Interrod enamel has the same composition as enamel rod, however a histologic distinction is made between the two because crystal orientation is different in each. Histology (from the Greek = 'tissue' is the study of the microscopic anatomy of cells and tissues of Plants and  The border where the crystals of enamel rods and crystals of interrod enamel meet is called the rod sheath. The rod sheath is an area identified in histologic sections of a Tooth. 
Striae of Retzius are stripes that appear on enamel when viewed microscopically in cross section. The Striae of Retzius are incremental growth lines seen in enamel and are results of enamel's development  Formed from changes in diameter of Tomes’ processes, these stripes demonstrate the growth of enamel, similar to the annual rings on a tree. Perikymata are shallow furrows where the striae of Retzius end. Perikymata ( Greek plural of perikyma) are the pits around the long microscopical prisms of Tooth enamel.  Darker than the other stripes, the neonatal line is a stripe that separates enamel formed before and after birth. The neonatal line is a particular band of incremental growth lines seen in histologic sections of a Tooth. 
Gnarled enamel is found at the cusps of teeth. Gnarled enamel is a description of enamel seen in histologic sections of a Tooth underneath a cusp  Its twisted appearance results from the orientation of enamel rods and the rows in which they lie.
Enamel formation is part of the overall process of tooth development. Tooth development is the complex process by which teeth form from Embryonic cells, grow, and erupt into the Mouth. When the tissues of the developing tooth are seen under a microscope, different cellular aggregations can be identified, including structures known as the enamel organ, dental lamina, and dental papilla. The enamel organ, also known as dental organ, is a cellular aggregation seen in histologic sections of a developing Tooth. The dental lamina is a band of epithelial tissue seen in histologic sections of a developing tooth. The dental papilla is a condensation of Ectomesenchymal cells called Odontoblasts seen in histologic sections of a developing tooth  The generally recognized stages of tooth development are the bud stage, cap stage, bell stage, and crown, or calcification, stage. Enamel formation is first seen in the crown stage.
Amelogenesis, or enamel formation, occurs after the first establishment of dentin, via cells known as ameloblasts. Amelogenesis is the formation of enamel on teeth and occurs during the crown stage of tooth development after Dentinogenesis, which is the formation of Human enamel forms at a rate of around 4 μm per day, beginning at the future location of cusps, around the third or fourth month of pregnancy. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International  As in all human processes, the creation of enamel is complex, but can generally be divided into two stages.  The first stage, called the secretory stage, involves proteins and an organic matrix forming a partially mineralized enamel. The second stage, called the maturation stage, completes enamel mineralization.
In the secretory stage, ameloblasts are polarized columnar cells. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called In the rough endoplasmic reticulum of these cells, enamel proteins are released into the surrounding area and contribute to what is known as the enamel matrix, which is then partially mineralized by the enzyme alkaline phosphatase. The endoplasmic reticulum (Greek endo = "within" (prefix plásma = "formed entity" Latin reticulum = "little net" or ER, is an Organelle Alkaline phosphatase ( ALP) ( is a Hydrolase Enzyme responsible for removing Phosphate groups from many types of molecules including  When this first layer is formed, the ameloblasts move away from the dentin, allowing for the development of Tomes’ processes at the apical pole of the cell. Enamel formation continues around the adjoining ameloblasts, resulting in a walled area, or pit, that houses a Tomes’ process, and also around the end of each Tomes’ process, resulting in a deposition of enamel matrix inside of each pit.  The matrix within the pit will eventually become an enamel rod, and the walls will eventually become interrod enamel. The only distinguishing factor between the two is the orientation of the calcium phosphate crystals.
In the maturation stage, the ameloblasts transport substances used in the formation of enamel. Histologically, the most notable aspect of this phase is that these cells become striated, or have a ruffled border.  These signs demonstrate that the ameloblasts have changed their function from production, as in the secretory stage, to transportation. Proteins used for the final mineralization process compose most of the transported material. The noteworthy proteins involved are amelogenins, ameloblastins, enamelins, and tuftelins. Amelogenin is a low-molecular-weight Protein found in developing Tooth enamel, and it belongs to a family of extracellular matrix (ECM proteins Ameloblastin, also known as amelin, is a gene-specific protein found in Tooth enamel. Enamelin is a protein found in developing Tooth enamel. About 30 % of developing enamel consists of protein of which enamelins comprise Tuftelin is an acidic phosphorylated Glycoprotein found in Tooth enamel.  During this process, amelogenins and ameloblastins are removed after use, leaving enamelins and tuftelin in the enamel.  By the end of this stage, the enamel has completed its mineralization.
At some point before the tooth erupts into the mouth, but after the maturation stage, the ameloblasts are broken down. Consequently, enamel, unlike many other tissues of the body, has no way to regenerate itself.  After destruction of enamel from decay or injury, neither the body nor a dentist can restore the enamel tissue. Enamel can be affected further by non-pathologic processes. The discoloration of teeth over time can result from exposure to substances such as tobacco, coffee, and tea. Tobacco is an Agricultural product recognized as an addictive drug processed from the fresh Leaves of plants in the genus Nicotiana. CoFFEE is an Open source Software for computer supported collaborative learning (CSCL in a digital classroom Tea refers to the cured agricultural product of the leaves leaf buds and internodes of Camellia sinensis, which have been prepared and cured for the market  This is partly due to material building up in the enamel, but is also an effect of the underlying dentin becoming sclerotic.  As a result, tooth color gradually darkens with age. Additionally, enamel becomes less permeable to fluids, less soluble to acid, and contains less water. 
|Amount of Enamel Formed at Birth||Enamel Mineralization Completed|
|Central Incisor||5/6||1. 5 months after birth|
|Lateral Incisor||2/3||2. 5 months after birth|
|Canine||1/3||9 months after birth|
|1st Molar||Cusps united; occlusal completely calcified|
and 1/2 to 3/4 crown height
|6 months after birth|
|2nd Molar||Cusps united; occlusal incompletely calcified;|
calcified tissue covers 1/5 to 1⁄4 crown height
|11 months after birth|
|Central Incisor||3/5||2. 5 months after birth|
|Lateral Incisor||3/5||3 months after birth|
|Canine||1/3||9 months after birth|
|1st Molar||Cusps united; occlusal|
|5. 5 months after birth|
|2nd Molar||Cusps united; occlusal|
|10 months after birth|
The high mineral content of enamel, which makes this tissue the hardest in the human body, also makes it susceptible to a demineralization process which often occurs as dental caries, otherwise known as cavities. Dental caries is a disease that damages Tooth structures resulting in what is commonly called tooth decay or cavities which are holes in the teeth  Demineralization occurs for several reasons, but the most important cause of tooth decay is the ingestion of sugars. Tooth cavities are caused when acids dissolve tooth enamel:
Sugars from candies, soft drinks, and even fruit juices play a significant role in tooth decay, and consequently in enamel destruction. Candy, specifically sugar candy, is a confection made from a concentrated solution of sugar in water to which a variety of flavorings and colorants is added Soft drink is a beverage that does not contain Alcohol. Carbonated soft drinks are commonly known as soda soda pop pop, or JUICE is a widely used non-commercial Software package for editing and analysing phytosociological data The mouth contains a great number and variety of bacteria, and when sucrose, the most common of sugars, coats the surface of the mouth, some intraoral bacteria interact with it and form lactic acid, which decreases the pH in the mouth. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Solubility of Pure SucroseTemperature(Cg Lactic acid ( IUPAC Systematic name: 2-hydroxypropanoic acid) also known as milk acid, is a Chemical compound that plays a role  Then, the hydroxylapatite crystals of enamel demineralize, allowing for greater bacterial invasion deeper into the tooth. The most important bacterium involved with tooth decay is Streptococcus mutans, but the number and type of bacteria varies with the progress of tooth destruction. Streptococcus mutans is a Gram-positive, facultatively anaerobic Bacteria commonly found in the Human Oral cavity and is 
Furthermore, tooth morphology dictates that the most common site for the initiation of dental caries is in the deep grooves, pits, and fissures of enamel. This is expected because these locations are impossible to reach with a toothbrush and allow for bacteria to reside there. When demineralization of enamel occurs, a dentist can use a sharp instrument, such as a dental explorer, and "feel a stick" at the location of the decay. A dental explorer (sickle probe is an instrument in Dentistry commonly used in the Dental armamentarium. As enamel continues to become less mineralized and is unable to prevent the encroachment of bacteria, the underlying dentin becomes affected as well. When dentin, which normally supports enamel, is destroyed by a physiologic condition or by decay, enamel is unable to compensate for its brittleness and breaks away from the tooth easily.
The extent to which tooth decay is likely, known as cariogenicity, depends on factors such as how long the sugar remains in the mouth. Caries is a progressive destruction of any kind of Bone structure including the Skull, Ribs and other bones or the teeth. Contrary to common belief, it is not the amount of sugar ingested but the frequency of sugar ingestion that is the most important factor in the causation of tooth decay.  When the pH in the mouth initially decreases from the ingestion of sugars, the enamel is demineralized and left vulnerable for about 30 minutes. Eating a greater quantity of sugar in one sitting does not increase the time of demineralization. Similarly, eating a lesser quantity of sugar in one sitting does not decrease the time of demineralization. Thus, eating a great quantity of sugar at one time in the day is less detrimental than is a very small quantity ingested in many intervals throughout the day. For example, in terms of oral health, it is better to eat a single dessert at dinner time than to snack on a bag of candy throughout the day. Dessert is a course that typically comes at the end of a meal usually consisting of sweet Food but sometimes of a strongly-flavored one such as some Cheeses The Candy, specifically sugar candy, is a confection made from a concentrated solution of sugar in water to which a variety of flavorings and colorants is added
In addition to bacterial invasion, enamel is also susceptible to other destructive forces. Bruxism, also known as clenching of or grinding on teeth, destroys enamel very quickly. Bruxism (from the Greek βρυγμός (brugmós gnashing of teeth) is the grinding of the teeth and is typically accompanied by the clenching The wear rate of enamel, called attrition, is 8 micrometers a year from normal factors. Attrition is the loss of Tooth structure by mechanical forces from opposing teeth A common misconception is that enamel wears away mostly from chewing, but actually teeth rarely touch during chewing. Furthermore, normal tooth contact is compensated physiologically by the periodontal ligaments (pdl) and the arrangement of dental occlusion. The periodontal ligament, commonly abbreviated as the PDL is a group of specialized Connective tissue fibers that essentially attach a tooth to the Alveolar bone Occlusion, in a dental context means simply the contact between teeth The truly destructive forces are the parafunctional movements, as found in bruxism, which can cause irreversible damage to the enamel.
Other nonbacterial processes of enamel destruction include abrasion (involving foreign elements, such as toothbrushes), erosion (involving chemical processes, such as lemon juice), and possibly abfraction (involving compressive and tensile forces). Abrasion is the loss of Tooth structure by mechanical forces from a foreign element Erosion, otherwise known as acid erosion, is the loss of tooth structure due to chemical dissolution by acids not of bacterial origin Abfraction is the loss of tooth structure from flexural forces 
Considering the vulnerability of enamel to demineralization and the daily menace of sugar ingestion, prevention of tooth decay is the best way to maintain the health of teeth. Oral hygiene is the practice of keeping the Mouth and Teeth clean in order to prevent dental problems and bad breath. Most countries have wide use of toothbrushes, which can reduce the number of bacteria and food particles on enamel. The toothbrush is an instrument consisting of a small Brush on a handle used to clean Teeth through Tooth brushing. Some isolated societies do not have access to toothbrushes, but it is common for those people to use other objects, such as sticks, to clean their teeth. In between two adjacent teeth, floss is used to wipe the enamel surfaces free of plaque and food particles to discourage bacterial growth. Dental floss is either a bundle of thin Nylon filaments or a plastic ( teflon or polyethylene) ribbon used to remove Food and Dental Dental plaque is Biofilm (usually colorless that builds up on the Teeth. Although neither floss nor toothbrushes can penetrate the deep grooves and pits of enamel, good general oral health habits can usually prevent enough bacterial growth to keep tooth decay from starting.
These methods of oral hygiene have been helped greatly by the use of fluoride. Oral hygiene is the practice of keeping the Mouth and Teeth clean in order to prevent dental problems and bad breath. Fluoride is the reduced form of Fluorine. Both organic and Inorganic compounds containing the element fluorine are considered fluorides Fluoride can be found in many locations naturally, such as the ocean and other water sources. Consequently, many seafood dishes contain fluoride. The recommended dosage of fluoride in drinking water is 1 part per million (ppm). Water of sufficient quality to serve as drinking water is termed potable water whether it is used for drinking or not "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly  Fluoride helps prevent dental decay by binding to the hydroxylapatite crystals in enamel.  The incorporated fluoride makes enamel more resistant to demineralization and, thus, resistant to decay.  Fluoride therapy is used to help teeth prevent dental decay. Fluoride therapy is the delivery of Fluoride to the Teeth Topically or systemically in order to prevent Tooth decay ( Dental caries
Many groups of people have spoken out against fluoridated drinking water. Water fluoridation is the addition of a chemical to increase the concentration of Fluoride Ions in Drinking water with the purpose of reducing the One example used by these advocates is the damage fluoride can do as fluorosis. Dental fluorosis is a health condition caused by an overdose of fluoride Fluorosis is a condition resulting from the overexposure to fluoride, especially between the ages of 6 months to 5 years, and appears as mottled enamel.  Consequently, the teeth look unsightly and, indeed, the incidence of dental decay in those teeth is very small. However, it is important to note that most substances, even beneficial ones, are detrimental when taken in extreme doses. Where fluoride is found naturally in high concentrations, filters are often used to decrease the amount of fluoride in water. For this reason, codes have been developed by dental professionals to limit the amount of fluoride a person should take.  These codes are supported by the American Dental Association and the American Academy of Pediatric Dentistry. The acute toxic dose of fluoride is ~5 mg/kg of body weight. Furthermore, whereas topical fluoride, found in toothpaste and mouthwashes, does not cause fluorosis, its effects are also less pervasive and not as long-lasting as those of systemic fluoride, such as when drinking fluorinated water.  For instance, all of a tooth's enamel gains the benefits of fluoride when it is ingested systemically, through fluoridated water or salt fluoridation (a common alternative in Europe). Only some of the outer surfaces of enamel can be reached by topical fluoride. Thus, despite fluoridation's detractors, most dental health care professionals and organizations agree that the inclusion of fluoride in public water has been one of the most effective methods of decreasing the prevalence of tooth decay.
Most dental restorations involve the removal of enamel. A dental restoration or dental filling is a Dental restorative material used artificially to restore the function integrity and morphology of missing tooth Frequently, the purpose of removal is to gain access to the underlying decay in the dentin or inflammation in the pulp. The dental pulp is the part in the center of a Tooth made up of living soft tissue and cells called Odontoblasts Anatomy This is typically the case in amalgam restorations and endodontic treatment. Amalgam is a commonly used dental filling that has been used for over 150 years A root canal is the commonly used term for the main canals within the Dentin of the tooth
Nonetheless, enamel can sometimes be removed before there is any decay present. The most popular example is the dental sealant. Dental sealants are a dental treatment consisting of applying a Plastic material to one or more teeth for the intended purpose of preventing Dental caries The process of placing dental sealants in the past involved removing enamel in the deep fissures and grooves of a tooth and replacing it with a restorative material.  Presently, it is more common to only remove decayed enamel if present. In spite of this, there are still cases where deep fissures and grooves in enamel are removed in order to prevent decay, and a sealant may or may not be placed depending on the situation. Sealants are unique in that they are preventative restorations for protection from future decay and have shown to reduce the risk of decay by 55% over 7 years. 
Aesthetics is another reason for the removal of enamel. Removing enamel is necessary when placing crowns and veneers to enhance the appearance of teeth. Crown refers to the restoration of teeth using materials that are fabricated by indirect methods which are cemented into place In Dentistry, a veneer is a thin layer of restorative material placed over a Tooth surface either to improve the Aesthetics of a tooth or to In both of these instances, it is important to keep in mind the orientation of enamel rods because it is possible to leave enamel unsupported by underlying dentin, leaving that portion of the prepared teeth more vulnerable to fracture. 
Invented in 1955, acid-etching employs dental etchants and is used frequently when bonding dental restoration to teeth.  This is important for long-term use of some materials, such as composites and sealants. Dental composites, also called white fillings, are a group of restorative materials used in dentistry Dental sealants are a dental treatment consisting of applying a Plastic material to one or more teeth for the intended purpose of preventing Dental caries  By dissolving minerals in enamel, etchants remove the outer 10 micrometers on the enamel surface and makes a porous layer 5–50 micrometers deep.  This roughens the enamel microscopically and results in a greater surface area on which to bond.
The effects of acid-etching on enamel can vary. Important variables are the amount of time the etchant is applied, the type of etchant used, and the current condition of the enamel. 
There are three types of patterns formed by acid-etching.  Type 1 is a pattern where predominantly the enamel rods are dissolved; type 2 is a pattern where predominantly the area around the enamel rods are dissolved; and type 3 is a pattern where there is no evidence left of any enamel rods. Besides concluding that type 1 is the most favorable pattern and type 3 the least, the explanation for these different patterns is not known for certain but is most commonly attributed to different crystal orientation in the enamel. 
Tooth whitening or tooth bleaching are procedures that attempt to lighten a tooth's color in either of two ways: by chemical or mechanical action. Tooth bleaching, also known as tooth whitening, is a common procedure in general dentistry but most especially in the field of Cosmetic dentistry. 
Working chemically, a bleaching agent is used to carry out an oxidation reaction in the enamel and dentin. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state  The agents most commonly used to intrinsically change the color of teeth are hydrogen peroxide and carbamide peroxide. Hydrogen peroxide (H2O2 is a very pale blue liquid which appears colorless in a dilute solution slightly more Viscous than water Carbamide peroxide, also called urea peroxide, urea hydrogen peroxide, and percarbamide, is an oxidising agent consisting of Hydrogen peroxide  A tooth whitening product with an overall low pH can put enamel at risk for decay or destruction by demineralization. Consequently, care should be taken and risk evaluated when choosing a product which is very acidic. 
Tooth whiteners in toothpastes work through a mechanical action. They have mild abrasives which aid in the removal of stains on enamel. Although this can be an effective method, it does not alter the intrinsic color of teeth. 
Microabrasion techniques employ both methods. An acid is used first to weaken the outer 22–27 micrometers of enamel in order to weaken it enough for the subsequent abrasive force.  This allows for removal of superficial stains in the enamel. If the discoloration is deeper or in the dentin, this method of tooth whitening will not be successful.
There are many different types of Amelogenesis imperfecta. Amelogenesis imperfecta presents with abnormal formation of the enamel or external layer of Teeth. The hypocalcification type, which is the most common, is an autosomal dominant condition that results in enamel that is not completely mineralized.  Consequently, enamel easily flakes off the teeth, which appear yellow because of the revealed dentin. The hypoplastic type is X-linked and results in normal enamel that appears in too little quantity, having the same effect as the most common type. Sex linkage is the phenotypic expression of an Allele that is related to the chromosomal sex of the individual 
Chronic bilirubin encephalopathy, which can result from erythroblastosis fetalis, is a disease which has numerous effects on an infant, but it can also cause enamel hypoplasia and green staining of enamel. Encephalopathy /ɛnˌsɛfəˈlɒpəθi/ literally means Disease of the Brain. Haemolytic disease of the newborn, also known as Haemolytic disease of the fetus and newborn, HDN, HDFN, or Erythroblastosis fetalis, is an 
Enamel hypoplasia is broadly defined to encompass all deviations from normal enamel in its various degrees of absence.  The missing enamel could be localized, forming a small pit, or it could be completely absent.
Erythropoietic porphyria is a genetic disease resulting in the deposition of porphyrins throughout the body. Porphyrias are a group of inherited or acquired disorders of certain Enzymes in the Heme biosynthetic pathway (also called Porphyrin pathway A porphyrin is a heterocyclic Macrocycle derived from four Pyrroline subunits interconnected via their α carbon atoms via Methine bridges (=CH- These deposits also occur in enamel and leave an appearance described as red in color and fluorescent. 
Tetracycline staining leads to brown bands on the areas of developing enamel. This article deals with the specific antibiotic called tetracycline Children up to age 8 can develop mottled enamel from taking tetracycline. As a result, tetracycline is contraindicated in pregnant women. Pregnancy ( Latin graviditas) is the carrying of one or more offspring known as a Fetus or Embryo, inside the Uterus of a Female
Celiac disease, an auto-immune disorder triggered by gluten allergies, also commonly results in demineralization of the enamel. Coeliac
For the most part, research has shown that formation in animals is almost identical to formation in humans. The enamel organ, including the dental papilla, and ameloblasts function similarly.  The variations of enamel that are present are infrequent but sometimes important. Differences exist, certainly, in the morphology, number, and types of teeth among animals.
Dogs are less likely than humans to have tooth decay due to the high pH of dog saliva, which prevents an acidic environment from forming and the subsequent demineralization of enamel which would occur.  In the event that tooth decay does occur (usually from trauma), dogs can receive dental fillings just as humans do. Similar to human teeth, the enamel of dogs is vulnerable to tetracycline staining. This article deals with the specific antibiotic called tetracycline Consequently, this risk must be accounted for when tetracycline antibiotic therapy is administered to young dogs.  Enamel hypoplasia may also occur in dogs. 
The mineral distribution in rodent enamel is different from that of monkeys, dogs, pigs, and humans. Rodentia is an order of Mammals also known as rodents, characterised by two continuously-growing incisors in the upper and lower jaws which must  In horse teeth, the enamel and dentin layers are intertwined with each other, which increases the strength and decreases the wear rate of those teeth. Horses' teeth are often used to estimate the animal's age hence the sayings "long in the tooth" and "Don't look a gift horse in the mouth"