NationMaster - Encyclopedia: Dental anatomy

Dental anatomy' or anatomy of teeth is a field of anatomy dedicated to the study human teeth structures. The development, appearance, and classification of teeth fall within its purvue, though the function of teeth as they contact one another is referred to as dental occlusion. Tooth formation begins prior to birth and their eventual morphology is dictated during this time. Dental anatomy is also a taxonomical science; it is concerned with the naming of teeth and the structures of which they are made. This information serves a practical purpose when rendering dental treatment.' Usually, there are 20 primary ("baby") teeth and 32 permanent teeth. Among primary teeth, 10 usually are found in the maxilla and the other 10 in the mandible. Among permanent teeth, 16 are found in the maxilla and the other 16 in the mandible. Most of the teeth have identifiable features that distinguishes them from others. Anatomical drawing of the human muscles from the EncyclopÃ©die. ... Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin for wise man or knowing man) under the family Hominidae (the great apes). ... This does not cite its references or sources. ... Birth is the process in animals by which an offspring is expelled from the body of its mother. ... Comparative anatomy is the study of similarities and differences in organisms. ... Look up taxonomy in Wiktionary, the free dictionary. ... Treatment may refer to: // Health Therapy - the act of remediation of a health problem. ... The maxillae are the largest bones of the face, except for the mandible, and form, by their union, the whole of the upper jaw. ... It has been suggested that this article or section be merged with jaw. ...

Tooth development

Tooth development is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. Although many diverse species have teeth, non-human tooth development is largely the same as in humans. For human teeth to have a healthy oral environment, enamel, dentin, cementum, and the periodontium must all develop during appropriate stages of fetal development. Primary (baby) teeth start to form between the sixth and eighth weeks in utero, and permanent teeth begin to form in the twentieth week in utero.^[1] If teeth do not start to develop at or near these times, they will not develop at all. Radiograph of lower right (from left to right) third, second, and first molars in different stages of development. ... Image File history File linksMetadata Download high resolution version (1844x1227, 437 KB) Summary Radiograph of lower right 3rd, 2nd, and 1st molars in an 11 year old child. ... Image File history File linksMetadata Download high resolution version (1844x1227, 437 KB) Summary Radiograph of lower right 3rd, 2nd, and 1st molars in an 11 year old child. ... It has been suggested that embryology be merged into this article or section. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... The term cell growth is used in two different ways in biology. ... Look up Mouth in Wiktionary, the free dictionary. ... In biology, a species is one of the basic units of biodiversity. ... Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin for wise man or knowing man) under the family Hominidae (the great apes). ... The mouth, also known as the buccal cavity or the oral cavity, is the opening through which an animal or human takes in food. ... 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 parts of the tooth. ... Parts of a tooth, including dentin Dentin (BE: dentine) is the substance between the enamel (substance in the crown) or cementum (substance in the root) of a tooth and the pulp chamber. ... Cementum is a specialized bony substance covering the root of a tooth. ... PeBold textriodontium is a word of Medical terminology for the specialized tissues surrounding and supporting the teeth. ... Fetal (U.S. English; Foetal UK English) development is the process in which a fetus (U.S. English; Foetus UK English) develops during gestation, from the times of conception until birth. ... ... In Utero is the third and final studio album from the American grunge band Nirvana, released in September 1993. ... Permanent teeth are the second set of teeth formed in humans. ...

A significant amount of research has focused on determining the processes that initiate tooth development. It is widely accepted that there is a factor within the tissues of the first branchial arch that is necessary for the development of teeth.^[2] The tooth bud (sometimes called the tooth germ) is an aggregation of cells that eventually forms a tooth and is organized into three parts: the enamel organ, the dental papilla and the dental follicle.^[3] In the development of vertebrate animals, the branchial arches (or pharyngeal arches) develop during the fourth and fifth week in utero as a series of mesodermal outpouchings on the left and right sides of the developing pharynx. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... The enamel organ, also known as dental organ, is a cellular aggregation 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 dental follicle is a sac containing the developing tooth and its odontogenic organ. ...

The enamel organ is composed of the outer enamel epithelium, inner enamel epithelium, stellate reticulum and stratum intermedium.^[3] These cells give rise to ameloblasts, which produce enamel and the reduced enamel epithelium. The growth of cervical loop cells into the deeper tissues forms Hertwig's Epithelial Root Sheath, which determines the root shape of the tooth. The dental papilla contains cells that develop into odontoblasts, which are dentin-forming cells.^[3] Additionally, the junction between the dental papilla and inner enamel epithelium determines the crown shape of a tooth.^[4] The dental follicle gives rise to three important entities: cementoblasts, osteoblasts, and fibroblasts. Cementoblasts form the cementum of a tooth. Osteoblasts give rise to the alveolar bone around the roots of teeth. Fibroblasts develop the periodontal ligaments which connect teeth to the alveolar bone through cementum.^[5] The outer enamel epithelium, also known as the external enamel epithelium, is a layer of cuboidal cells located on the periphery of the enamel organ in a developing tooth. ... The inner enamel epithelium, also known as the internal enamel epithelium, is a layer of cells located on the rim nearest the dental papilla of the enamel organ in a developing tooth. ... The stellate reticulum is a group of cells located in the center of the enamel organ of a developing tooth. ... The stratum intermedium in a developing tooth is a layer of cells between the inner enamel epithelium and the newly forming cells of the stellate reticulum. ... Ameloblast is the blast that synthezises enamel proteins that later mineralise to form enamel on teeth. ... The reduced enamel epithelium, sometimes called reduced dental epithelium, overlies a developing tooth and is formed by two layers: a layer of ameloblast cells and the adjacent layer of cuboidal cells from the dental lamina. ... The Hertwigs epithelial root sheath (frequently abbreviated as HERS) is a proliferation of epithelial cells located at the cervical loop of the enamel organ in a developing tooth. ... An odontoblast is a biological cell that is part of the outer surface of the dental pulp, and whose biological function is dentinogenesis, which is the creation of dentin, the substance under the tooth enamel and ivory. ... A Cementoblast is a biological cell that forms from the follicular cells around the root of a tooth, and whose biological function is cementogenesis, which is the creation of cementum. ... An osteoblast (from the Greek words for bone and to build) is a mononucleate cell which produces a protein that produces osteoid. ... Mouse Embryonic Fibroblasts (MEF) A fibroblast is a type of cell that synthesizes and maintains the extracellular matrix of many animal tissues. ... The alveolar process (processus alveolaris), also referred to as the alveolar bone, is the bone found in the jaws of a mouth containing the socket of teeth. ... // Headline text The periodontal ligaments are considered part of the periodontium, as they are supporting tissue of a tooth. ...

Tooth development is commonly divided into the following stages: the bud stage, the cap, the bell, and finally maturation. The staging of tooth development is an attempt to categorize changes that take place along a continuum; frequently it is difficult to decide what stage should be assigned to a particular developing tooth.^[2] This determination is further complicated by the varying appearance of different histologic sections of the same developing tooth, which can appear to be different stages.

Identification

Nomenclature

Teeth are named by their set, arch, class, type, and side. Teeth can belong to one of two sets of teeth: primary ("baby") teeth or permanent teeth. Often, "deciduous" may be used in place of "primary", and "succedaneous" may be used for "permanent". Further, the name depends upon which arch the tooth is found in. The term, "maxillary", is given to teeth in the upper jaw and "mandibular" to those in the lower jaw. There are four classes of teeth: incisors, canines, premolars, and molars. Premolars around found only in permanent teeth; there are no primary premolars. Within each class, teeth may be classified into different traits. Incisors are divided further into central and lateral incisors. Among premolars and molars, there are 1st and 2nd premolars, and 1st, 2nd, and 3rd molars. The side of the mouth in which a tooth is found may also be included in the name. For example, a specific name for a tooth may be "primary maxillary left lateral incisor." Incisors are the first kind of tooth in heterodont mammals. ... A canine may refer to: a canine tooth. ... The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. ... Molar may refer to: Molar (tooth), the fourth kind of tooth in mammals. ...

Numbering systems

There are several different dental notation systems for associating information to a specific tooth. The three most commons systems are the FDI World Dental Federation notation, Universal numbering system (dental), and Palmer notation method. The FDI system is used worldwide, and the universal is used widely in the USA. Dentists, in writing or speech, use several different Dental notation systems for associating information to a specific tooth. ... FDI World Dental Federation notation is widely used by dentists internationally to associate information to a specific tooth. ... The Universal numbering system is a dental notation system for associating information to a specific tooth, and is commonly used in the United States. ... Palmer notation is a system used by dentists to associate information to a specific tooth. ...

Although the Palmer notation was supposedly superseded by the FDI World Dental Federation notation, it overwhelming continues to be the preferred method used by dental students and practitioners in the United Kingdom.^[6] It was originally termed the "Zsigmondy system" after the Austrian dentist Adolf Zsigmondy who developed the idea in 1861, using a Zsigmondy cross to record quadrants of tooth positions.^[7]. The Palmer notation consists of a symbol (┘└ ┐┌) designating in which quadrant the tooth is found and a number indicating the position from the midline. Permanent teeth are numbered 1 to 8, and primary teeth are indicated by a letter A to E. The universal numbering system uses a unique letter or number for each tooth. The uppercase letters A through T are used for primary teeth and the numbers 1 - 32 are used for permanent teeth. The tooth designated "1" is the right maxillary third molar and the count continues along the upper teeth to the left side. Then the count begins at the left mandibular third molar, designated number 17, and continues along the bottom teeth to the right side. The FDI system uses a two-digit numbering system in which the first number represents a tooth's quadrant and the second number represents the number of the tooth from the midline of the face. For permanent teeth, the upper right teeth begin with the number, "1". The upper left teeth begin with the number, "2". The lower left teeth begin with the number, "3". The lower right teeth begin with the number, "4". For primary teeth, the sequence of numbers goes 5, 6, 7, and 8 for the teeth in the upper left, upper right, lower right, and lower left respectively. FDI World Dental Federation notation is widely used by dentists internationally to associate information to a specific tooth. ... 1861 is a common year starting on Tuesday. ...

As a result, any given tooth has three different ways to identify it, depending on which notation system is used. The permanent right maxillary central incisor is identified by the number "8" in the universal system. In the FDI system, the same tooth is identified by the number "11". The palmer system uses the number and symbol, ¹┘, to identify the tooth. Further confusion may result if a number is given on a tooth without assuming (or specifying) a common notation method. Since the number, "12", may signify the permanent left maxillary first premolar in the universal system or the permanent right maxillary lateral incisor in the FDI system, the notation being used must be clear to prevent confusion.

Anatomic landmarks

Crown and root

The crown of a tooth can be used to describe two situations. The anatomic crown of a tooth is designated by the area above the cementoenamel junction (CEJ) and is consequently covered in enamel. Also, it is possible to describe the clinical crown of a tooth as any parts visible in the mouth, but frequently the anatomic crown is meant when the term is used. The majority of the crown is composed of dentin, with the pulp chamber found in the center. The crown is only found within bone before eruption into the mouth. Afterwards, it is almost always visible. In dentistry, crown refers to the anatomical area of teeth, usually covered by enamel. ... The cementoenamel junction, frequently abbreviated as the CEJ, is an anatomical landmark identified on a tooth. ... The removed bone reveals permanent teeth below the roots of primary teeth. ...

The root of a tooth can also be used as an anatomic or clinical situation. The anatomic root is found below the cementoenamel junction and is covered with cementum, whereas the clinical root is any part of a tooth not visible in the mouth. Similarly, the anatomic root is assumed in most circumstances. Dentin composes most of the root, which normally have pulp canals. The roots of teeth may be single in number or multiple. Canines and most premolars, except for maxillary first premolars, usually have one root. Maxillary first premolars and mandibular molars usually have two roots. Maxillary molars usually have three roots. The tooth is supported in bone by an attachment apparatus, known as the periodontium, which interacts with the root. PeBold textriodontium is a word of Medical terminology for the specialized tissues surrounding and supporting the teeth. ...

Surfaces

Surfaces that are nearest the cheeks or lips are referred to as "facial", and those nearest the tongue are known as "lingual." Facial surfaces can be subdivided into "buccal" (when found on posterior teeth nearest the cheeks) and "labial" (when found on anterior teeth nearest the lips). Lingual surfaces can also be described as "palatal" when found on maxillary teeth beside the hard palate. Look up Cheek in Wiktionary, the free dictionary The Cheeks are the fleshy area of the face below the eyes and between the nose and the left or right ear, the skin being suspended by the chin and the yaws. ... This article or section does not cite its references or sources. ... For other uses, see Tongue (disambiguation). ... The hard palate is a thin horizontal bony plate of the skull, otherwise known as the palatine process of the maxilla, located in the roof of the mouth. ...

Surfaces that aid in chewing are known as "occlusal" on posterior teeth and "incisal" on anterior teeth. Surfaces nearest the junction of the crown and root are referred to as "cervical", and those closest to the apex of the root are referred to as "apical". The words "mesial" and "distal" are also used as descriptions. Mesial signifies a surface closer to the median line of the face, which is located on a vertical axis between the eyes, down the nose, and between the contact of the central incisors. Surfaces further away from the median line are described as distal. Image:X:uikfhduishnei. ... A human eye. ... Human nose in profile A typical bulbous human nose Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for respiration. ...

Cusp

A cusp is an elevation on an occlusal surface of posterior teeth and canines. It contributes to a significant portion of the tooth's surface. Maxillary and mandibular canines have one cusp. Maxillary premolars and the mandibular first premolars usually have two cusps. Mandibular second premolars frequently have three cusps--- one buccal and two lingual. Maxillary molars have two buccal cusps and two lingual cusps. A fifth cusp that may form on these teeth are known as the cusp of Carabelli. Mandibular molars may have five or four cusps. Carabellis tubercle is a degeneration cusp of upper first molar in the mesial-lingual portion also known as the Cusp of Carabelli. ...

Cingulum

A cingulum is a convexity found on the lingual surface of anterior teeth. It is frequently identifiable as an inverted V-shaped ridge.^[8] On lower incisors, a cingulum usually does not develop. In dentistry, cingulum (latin: girdle or belt)[1] refers to the anatomical feature of incisors. ...

Ridges

Developmental groove

Embrasures

Mammelons

Mammelons are usually found as three small bumps on the incisal edges of anterior teeth. Since this part of the tooth is the first to wear away from attrition, mammelons may not visible on teeth of older people. Instead, the best chance to see this characteristic is soon after eruption of the tooth into the mouth. In dentistry, mammelons refer to an anatomical feature on the incisal edges of teeth. ... Attrition is the loss of tooth structure due to by mechanical forces from opposing teeth. ... The removed bone reveals permanent teeth below the roots of primary teeth. ...

Distinguishing characteristics of teeth

Maxillary central incisor

The maxillary central incisor is usually the most visible tooth, since it is the top center two teeth in the front of a mouth, and it is located mesial to the maxillary lateral incisor. As with all incisors, their function is for shearing or cutting food during mastication (chewing). There are no cusps on the teeth. Instead, the surface area of the tooth used in eating is called the incisal ridge or incisal edge. Though relatively the same, there are some minor differences between the primary maxillary central incisor and that of the permanent maxillary central incisor. The maxillary central incisor is usually the most visible tooth, since it is the top center two teeth in the front of a mouth, and it is located mesial (closer to the midline of the face) to the maxillary lateral incisor. ... The maxillary lateral incisor is the tooth located distally (away from the midline of the face) from both maxillary central incisors of the mouth and mesially (toward the midline of the face) from both maxillary canines. ... Shear is a form of structural failure. ... Mastication or chewing is the process by which food is torn and/or crushed by teeth. ...

The overall length of the deciduous maxillary central incisor is 16 mm on average, with the crown being 6 mm and the root being 10 mm.^[9] In comparison to the permanent maxillary central incisor, the ratio of the root length to the crown length is greater in the deciduous tooth. The diameter of the crown mesiodistally is greater than the length cervicoincisally, which makes the tooth appear wider rather than taller from a labial viewpoint.

The permanent maxillary central incisor is the widest tooth mesiodistally in comparison to any other anterior tooth. It is larger than the neighboring lateral incisor and is usually not as convex on its labial surface. As a result, the central incisor appears to be more rectangular or square in shape. The mesial incisal angle is sharper than the distal incisal angle. When this tooth is newly erupted into the mouth, the incisal edges have three rounded features called mammelons.^[10] Mammelons disappear with time as the enamel wears away by friction.

References

^ A. R. Ten Cate, Oral Histology: Development, Structure, and Function, 5th ed. (Saint Louis: Mosby-Year Book, 1998), p. 95. ISBN 0-8151-2952-1.
^ ^a ^b A. R. Ten Cate, Oral Histology: Development, Structure, and Function, 5th ed. (Saint Louis: Mosby-Year Book, 1998), p. 81. ISBN 0-8151-2952-1.
^ ^a ^b ^c *University of Texas Medical Branch. "Lab Exercises: Tooth development." Page found here.
^ A. R. Ten Cate, Oral Histology: Development, Structure, and Function, 5th ed. (Saint Louis: Mosby-Year Book, 1998), pp. 86 and 102. ISBN 0-8151-2952-1.
^ *Ross, Michael H., Gordon I. Kaye, and Wojciech Pawlina. Histology: a text and atlas. 4th edition, p. 453. 2003. ISBN 0-683-30242-6.
^ Blinkhorn A, Choi C, Paget H (1998). "An investigation into the use of the FDI tooth notation system by dental schools in the UK.". Eur J Dent Educ 2 (1): 39-41. PMID 9588962.
^ Huszár G (1989). "[The role of the life and works of Adolf Zsigmondy and Ottó Zsigmondy in the history of dentistry]". Fogorv Sz 82 (12): 357-63. PMID 2689240.
^ Gray, Henry. XI. Splanchnology. 2a. The Mouth, from "Gray's Anatomy of the Human Body". 20th U.S. edition. 1918.
^ Ash, Major M. and Stanley J. Nelson. Wheeler’s Dental Anatomy, Physiology, and Occlusion. 8th edition. 2003. p. 75. ISBN 0-7216-9382-2.
^ The Permanent Incisor Teeth, hosted by the University of Illinois at Chicago (UIC), accessed on June 8, 1006.

Contents

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