Maxillary central incisor
Encyclopedia
The maxillary central incisor is a human tooth
in the front upper jaw, or maxilla
, and is usually the most visible of all teeth in the mouth. It is located mesial
(closer to the midline of the face) to the maxillary lateral incisor
. As with all incisor
s, 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 an incisal
ridge or incisal edge. Formation of these teeth begin at 14 weeks in utero for the deciduous
(baby) set and 3–4 months of age for the permanent
set.
There are some minor differences between the deciduous maxillary central incisor and that of the permanent maxillary central incisor. The deciduous tooth appears in the mouth at 3–18 months of age, with 6 months being the average and is replaced by the permanent tooth around 7–8 years of age. The permanent tooth is larger and is longer
than it is wide. The maxillary central incisors contact each other at the midline of the face. The mandibular central incisor
s are the only other type of teeth to do so. The position of these teeth may determine the existence of an open bite or diastema
. As with all teeth, variations of size, shape, and color exist among people. Systemic disease, such as syphilis
, may affect the appearance of teeth.
to identify teeth. In the universal system of notation
, the deciduous maxillary central incisors are designated by a letter written in uppercase. The right deciduous maxillary central incisor is known as "E", and the left one is known as "F". The permanent maxillary central incisors are designated by a number. The right permanent maxillary central incisor is known as "8", and the left one is known as "9".
In the Palmer notation
, a letter is used in conjunction with a symbol designating in which quadrant the tooth is found. For the deciduous teeth, the left and right central incisor would have the same letter, "A", but the right one would have the symbol, "┘", underneath it, while the left one would have, "└". For the permanent teeth, the left and right central incisor would have the same number, "1", but the right one would have the symbol, "┘", underneath it, while the left one would have, "└".
The FDI World Dental Federation notation
has a different system of numbering system than the previous two. Thus, the right deciduous maxillary central incisor is known as "51", and the left one is known as "61". For the permanent maxillary central incisor, the right one is known as "11", and the left one is known as "21".
which eventually form a tooth are derived from the ectoderm
of the first branchial arch
and the ectomesenchyme
of the neural crest
. As in all cases of tooth development, the first hard tissue to begin forming is dentin
, with enamel
appearing immediately afterwards.
The deciduous maxillary central incisor begins to undergo mineralization 14 weeks in utero, and at birth 5/6ths of the enamel is formed. The crown
of the tooth is completed 1.5 months after birth and erupts
into the mouth at around 10 months of age, making these teeth usually the second type of teeth to appear. The root completes its formation when the child is 1.5 years old.
The permanent maxillary central incisor begins to undergo mineralization when a child is 3–4 months of age. The crown of the tooth is completed at around 4–5 years of age and erupts into the mouth at 7–8 years of age. The root completes its formation when the child is 10 years old.
is greater than the length cervicoincisally
, which makes the tooth appear wider rather than taller from a labial
viewpoint.
The marginal ridges and the cingulum of the tooth are well-developed. The cingulum reaches incisally
a great length and is large enough to create small fossa on either side of it. Depicted by the cementoenamel junction
, the cervical
line is the border between the root and crown of a tooth. On the mesial
and distal
surfaces, the cervical line curves incisally, which is also seen in the permanent maxillary central incisor.
The root of this tooth is cone-shaped with a rounded apex. Most of the surfaces are smooth, but the mesial surface of the root may have a developmental groove or a concavity.
s. Mammelons disappear with time as the enamel wears away by friction.
Generally, there are gender differences in the appearance of this tooth. In males, the size of the maxillary central incisor is larger usually than in females. Gender differences in enamel thicknes and dentin width are low. Age differences in the gingival-incisal
length of maxillary central incisors are seen and are attributed to normal attrition
occurring throughout life. Thus, younger individuals have a greater gingival incisal length of the teeth than older individuals.
(the point furthest away from the central axis of the tooth) is closer to the mesioincisal angle on the mesial side while more apical on the distal side.
The distal outline of the crown is more convex than the mesial outline, and the distoincisal angle is not as sharp as the mesoincisal angle.
After the mammelons are worn away, the incisal edge of the maxillary central incisor is straight mesiodistally. The center of the incisal edge curves slightly downward in the center of the tooth. The cervical line, which is seen as the border between the crown and the root of the tooth, is closer to the apex of the root in the center of the tooth. This makes the cervical line appear as a semicircle in shape.
From this view, the root is blunt and cone-shaped. Although there is a large amount of variation between people, the length of the root is usually 2–3 mm longer than the length of the crown. Large curvatures of the root are usually not seen in this tooth.
near the cervical line and has a large concavity, called the lingual fossa. Along the mesial and distal sides are slightly raised portions called marginal ridges. The lingual incisal edge is also raised slightly to the level of the marginal ridges. The lingual fossa is bordered incisally by the lingual incisal edge, mesially by the mesial marginal ridge, distally by the distal marginal ridge, and cervically by the cingulum. Developmental grooves are found on the cingulum and lying into the lingual fossa.
This side of the tooth tapers in size from the labial side of the tooth. As a result, the mesial and distal sides of the tooth are further away on the labial side than on the lingual side. Furthermore, a cross-section of the tooth at the cervical line would show a general triangle appearance. One of the triangle's sides would be the facial surface, and the other two sides would be the mesial side and the slightly shorter distal side.
The crest of curvature for the palatal and labial surfaces is located directly incisally to the cervical line. The labial surface of the crown is convex from the crest of curvature to the incisal edge. The lingual surface of the crown is convex near the cingulum and near the incisal edge, but for the most part is concave along the surface between those two areas.
More than any other tooth in the mouth, the cervical line from this view curves tremendously toward the incisal. In an average crown length of 10.5 to 11 mm, the curvature of the cervical line in a maxillary central incisor is 3 to 4 mm.
is the location of the nerve and blood supply of a tooth. In the deciduous maxillary central incisor, endodontic
treatment is less frequent. In the permanent maxillary central incisor, root canal
treatment can be effective. There frequently are three pulp horns in this tooth. In nearly all maxillary central incisors, there is one canal with one apex. During root canal therapy, access into the pulp is frequently located centrally on the lingual surface between the incisal edge and the cingulum. At the level of the cervical line, the shape of the canal is triangular but becomes circular at the middle level of the root. Although the root is generally straight, the most common points of curvature is near the apex, and their direction is more common toward the distal and lingual.
Contact with adjacent teeth in the same arch is referred to as interproximal contacts. The maxillary central incisors are one of only two types of teeth which has an interproximal contact with itself. The other type of teeth is the mandibular central incisor
s. In usually preferred and healthy states, the central incisors touch in the incisal third of the teeth. On the other hand, the contact between the central incisor and the lateral incisor is nearer the gingiva at the location between the incisal and middle thirds of the tooth's crown.
. Normal occlusion is Class I occlusion.
When the teeth are biting down, the maxillary central incisors occlude with the mandibular central and lateral incisors. The contact point of the mandibular teeth is in the lingual fossa of the maxillary central incisor about 4 mm gingivally from the incisal edge. In this position, the maxillary incisors cover nearly half of the mandibular incisors' crowns. When the maxillary and mandibular incisors do not contact even when the mouth is fully closed, an anterior open bite occurs. This misalignment of teeth may result from some habits, such as thumb-sucking. On the other hand, when the contact of the mandibular incisors to the maxillary incisors is near or completely on the gingiva, a deep bite occurs.
and some East Asian
populations, is possibly a trait
retained from an indigenous East Asian archaic human ancestor Homo Erectus Pekinensis
. Among its features are shovel-shaped incisors
that derive their name from the deeper-than-normal lingual fossa and prominent marginal ridges of the teeth. When seen from lingual view, the tooth is said to resemble a shovel
and are rotated slightly inward. It is also common to see signs of attrition, which is wear over time from other tooth contact. The lingual of maxillary incisors and the facial of mandibular incisors are the most common places for attrition to occur.
When space exists between the contacts of the maxillary central incisors, the condition is referred to as a diastema
or "gap tooth." One frequent cause of the space is the presence of a large labial frenum
from the upper lip extending near the teeth. Treatment depends upon the cause and extent of the gap. Periodontal surgery may be required to reduce the frenum. A small space may be corrected with a filling
, veneer
, or crown
. Larger spaces may require orthodontics.
The maxillary incisors, both the central and lateral, are the most likely teeth to have a talon cusp
, which is an extra cusp on the lingual surface. Talon cusps have been found in to range in less than 1% to 6% of the population, and 33% of cases occur on the permanent maxillary central incisor. Deciduous teeth are unlikely to have talon cusps. Also, the permanent maxillary incisors are the most likely teeth to have a dilaceration
, which is a sharp curve on a tooth.
All incisors have the potential to be affected by a case of congentital syphilis
, which can cause a notch to form on the incisal edges of these teeth. These teeth, sometimes described as screwdriver-shaped, are called "Hutchinson's incisors
." They serve as part of Hutchinson's triad
, which also includes interstitial keratitis
and eighth
nerve
deafness.
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...
in the front upper jaw, or maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
, and is usually the most visible of all teeth in the mouth. It is located mesial
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
(closer to the midline of the face) to the maxillary lateral incisor
Maxillary lateral incisor
The Maxillary lateral incisor is a tooth that is located distally from both maxillary central incisors of the mouth and mesially from both maxillary canines. As with all incisors, their function is for shearing or cutting food during mastication, commonly known as chewing. There are no cusps on...
. As with all incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s, their function is for shearing
Shearing (physics)
Shearing in continuum mechanics refers to the occurrence of a shear strain, which is a deformation of a material substance in which parallel internal surfaces slide past one another. It is induced by a shear stress in the material...
or cutting food during mastication
Mastication
Mastication or chewing is the process by which food is crushed and ground by teeth. It is the first step of digestion and it increases the surface area of foods to allow more efficient break down by enzymes. During the mastication process, the food is positioned between the teeth for grinding by...
(chewing). There are no cusps
Cusp (dentistry)
A cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
on the teeth. Instead, the surface area of the tooth used in eating is called an incisal
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
ridge or incisal edge. Formation of these teeth begin at 14 weeks in utero for the deciduous
Deciduous teeth
Deciduous teeth, otherwise known as reborner teeth, baby teeth, temporary teeth and primary teeth, are the first set of teeth in the growth development of humans and many other mammals. In some Asian countries they are referred to as fall teeth as they will eventually fall out, while in almost all...
(baby) set and 3–4 months of age for the permanent
Permanent teeth
Permanent teeth are the second set of teeth formed in humans. There are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mandibular premolars, two maxillary and two mandibular canines, four maxillary and four mandibular incisors.The first...
set.
There are some minor differences between the deciduous maxillary central incisor and that of the permanent maxillary central incisor. The deciduous tooth appears in the mouth at 3–18 months of age, with 6 months being the average and is replaced by the permanent tooth around 7–8 years of age. The permanent tooth is larger and is longer
Length
In geometric measurements, length most commonly refers to the longest dimension of an object.In certain contexts, the term "length" is reserved for a certain dimension of an object along which the length is measured. For example it is possible to cut a length of a wire which is shorter than wire...
than it is wide. The maxillary central incisors contact each other at the midline of the face. The mandibular central incisor
Mandibular central incisor
The mandibular central incisor is the tooth located on the jaw, adjacent to the midline of the face. It is mesial from both mandibular lateral incisors. As with all incisors, its function includes shearing or cutting food during mastication, commonly known as chewing. There are no cusps on the...
s are the only other type of teeth to do so. The position of these teeth may determine the existence of an open bite or diastema
Diastema (dentistry)
Diastema is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars.-In humans:...
. As with all teeth, variations of size, shape, and color exist among people. Systemic disease, such as syphilis
Syphilis
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...
, may affect the appearance of teeth.
Notation
Dentistry has several systems of notationDental notation
Dentists, in writing or speech, use several different dental notation systems for associating information to a specific tooth. The three most common systems are the FDI World Dental Federation notation, Universal numbering system , and Palmer notation method...
to identify teeth. In the universal system of notation
Universal numbering system (dental)
The Universal numbering system is a dental notation system for associating information to a specific tooth, and is commonly used in the United States.The designations "left" and "right" on the chart correspond to the patient's left and right, respectively....
, the deciduous maxillary central incisors are designated by a letter written in uppercase. The right deciduous maxillary central incisor is known as "E", and the left one is known as "F". The permanent maxillary central incisors are designated by a number. The right permanent maxillary central incisor is known as "8", and the left one is known as "9".
In the Palmer notation
Palmer notation
Palmer notation is a system used by dentists to associate information to a specific tooth. Although supposedly superseded by the FDI World Dental Federation notation, it overwhelmingly continues to be the preferred method used by orthodontists, dental students and practitioners in the United...
, a letter is used in conjunction with a symbol designating in which quadrant the tooth is found. For the deciduous teeth, the left and right central incisor would have the same letter, "A", but the right one would have the symbol, "┘", underneath it, while the left one would have, "└". For the permanent teeth, the left and right central incisor would have the same number, "1", but the right one would have the symbol, "┘", underneath it, while the left one would have, "└".
The FDI World Dental Federation notation
FDI World Dental Federation notation
FDI World Dental Federation notation is widely used by dentists internationally to associate information to a specific tooth.Developed by the FDI World Dental Federation, World Dental Federation notation is also known as ISO 3950 notation....
has a different system of numbering system than the previous two. Thus, the right deciduous maxillary central incisor is known as "51", and the left one is known as "61". For the permanent maxillary central incisor, the right one is known as "11", and the left one is known as "21".
Development
The aggregate of cellsCell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
which eventually form a tooth are derived from the ectoderm
Germ layer
A germ layer, occasionally referred to as a germinal epithelium, is a group of cells, formed during animal embryogenesis. Germ layers are particularly pronounced in the vertebrates; however, all animals more complex than sponges produce two or three primary tissue layers...
of the first branchial arch
First branchial arch
The first branchial arch, also called the first pharyngeal arch and mandibular arch, is the first of six branchial arches that develops in fetal life during the fourth week of development...
and the ectomesenchyme
Ectomesenchyme
Ectomesenchyme has similar properties to mesenchyme. The major difference is that ectomesenchyme is usually considered to arise from neural crest cells, which are a critical group of cells that form in the cranial region during early vertebrate development...
of the neural crest
Neural crest
Neural crest cells are a transient, multipotent, migratory cell population unique to vertebrates that gives rise to a diverse cell lineage including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia....
. As in all cases of tooth development, the first hard tissue to begin forming is dentin
Dentin
Dentine is a calcified tissue of the body, and along with enamel, cementum, and pulp is one of the four major components of teeth. Usually, it is covered by enamel on the crown and cementum on the root and surrounds the entire pulp...
, with enamel
Tooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...
appearing immediately afterwards.
The deciduous maxillary central incisor begins to undergo mineralization 14 weeks in utero, and at birth 5/6ths of the enamel is formed. The crown
Crown (tooth)
In dentistry, crown refers to the anatomical area of teeth, usually covered by enamel. The crown is usually visible in the mouth after developing below the gingiva and then erupting into place.-References:...
of the tooth is completed 1.5 months after birth and erupts
Tooth eruption
Tooth eruption is a process in tooth development in which the teeth enter the mouth and become visible. It is currently believed that the periodontal ligaments play an important role in tooth eruption...
into the mouth at around 10 months of age, making these teeth usually the second type of teeth to appear. The root completes its formation when the child is 1.5 years old.
The permanent maxillary central incisor begins to undergo mineralization when a child is 3–4 months of age. The crown of the tooth is completed at around 4–5 years of age and erupts into the mouth at 7–8 years of age. The root completes its formation when the child is 10 years old.
Deciduous dentition
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. 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 mesiodistallyCommonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
is greater than the length cervicoincisally
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
, which makes the tooth appear wider rather than taller from a labial
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
viewpoint.
The marginal ridges and the cingulum of the tooth are well-developed. The cingulum reaches incisally
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
a great length and is large enough to create small fossa on either side of it. Depicted by the cementoenamel junction
Cementoenamel junction
The cementoenamel junction, frequently abbreviated as the CEJ, is an anatomical border identified on a tooth. It is the location where the enamel, which covers the anatomical crown of a tooth, and the cementum, which covers the anatomical root of a tooth, meet...
, the cervical
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
line is the border between the root and crown of a tooth. On the mesial
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
and distal
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
surfaces, the cervical line curves incisally, which is also seen in the permanent maxillary central incisor.
The root of this tooth is cone-shaped with a rounded apex. Most of the surfaces are smooth, but the mesial surface of the root may have a developmental groove or a concavity.
Permanent dentition
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 mammelonMammelon
In dentistry, mammelons refer to an anatomical feature on the incisal edges of teeth. Frequently found on erupting central and lateral incisors, mammelons appear as three little bumps. Since this part of the tooth is the first to wear away from attrition, mammelons may not visible on teeth of...
s. Mammelons disappear with time as the enamel wears away by friction.
Generally, there are gender differences in the appearance of this tooth. In males, the size of the maxillary central incisor is larger usually than in females. Gender differences in enamel thicknes and dentin width are low. Age differences in the gingival-incisal
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
length of maxillary central incisors are seen and are attributed to normal attrition
Attrition (dental)
Attrition is the loss of teeth structure by mechanical forces from opposing teeth. Attrition initially affects the enamel and, if unchecked, may proceed to the underlying dentin. Once past the enamel, attrition quickly destroys the softer dentin. Erosion is a very important contributing factor to...
occurring throughout life. Thus, younger individuals have a greater gingival incisal length of the teeth than older individuals.
Labial view
The labial view of this tooth considers the portion of the tooth visible from the side where the lips would be. The mesial outline of the tooth is straight or slightly convex, whereas the distal outline is much more convex. Consequently, the height of curvatureHeight of curvature
Height of curvature in the tooth can be defined as the line encircling a tooth at its greatest bulge to a selected path of insertion.-Locations of height of curvature:...
(the point furthest away from the central axis of the tooth) is closer to the mesioincisal angle on the mesial side while more apical on the distal side.
The distal outline of the crown is more convex than the mesial outline, and the distoincisal angle is not as sharp as the mesoincisal angle.
After the mammelons are worn away, the incisal edge of the maxillary central incisor is straight mesiodistally. The center of the incisal edge curves slightly downward in the center of the tooth. The cervical line, which is seen as the border between the crown and the root of the tooth, is closer to the apex of the root in the center of the tooth. This makes the cervical line appear as a semicircle in shape.
From this view, the root is blunt and cone-shaped. Although there is a large amount of variation between people, the length of the root is usually 2–3 mm longer than the length of the crown. Large curvatures of the root are usually not seen in this tooth.
Lingual view
The lingual view of this tooth considers the portion of the tooth visible from the side where the tongue would be. The lingual side of the maxillary central incisor has a small convexity, called a cingulumCingulum (tooth)
In dentistry, cingulum refers to an anatomical feature of the anterior teeth . It refers to the portion of the teeth, occurring on the lingual or palatal aspects, that forms a convex protuberance at the cervical third of the anatomic crown. It represents the lingual or palatal developmental lobe...
near the cervical line and has a large concavity, called the lingual fossa. Along the mesial and distal sides are slightly raised portions called marginal ridges. The lingual incisal edge is also raised slightly to the level of the marginal ridges. The lingual fossa is bordered incisally by the lingual incisal edge, mesially by the mesial marginal ridge, distally by the distal marginal ridge, and cervically by the cingulum. Developmental grooves are found on the cingulum and lying into the lingual fossa.
This side of the tooth tapers in size from the labial side of the tooth. As a result, the mesial and distal sides of the tooth are further away on the labial side than on the lingual side. Furthermore, a cross-section of the tooth at the cervical line would show a general triangle appearance. One of the triangle's sides would be the facial surface, and the other two sides would be the mesial side and the slightly shorter distal side.
Mesial view
The mesial view of this tooth considers the portion of the tooth visible from the side closest to where the middle line of the face would be.the mesial exis should be parallel to the midline. The mesial side of the maxillary central incisor shows the crown of the tooth as a triangle with the point at the incisal edge and the base at the cervix. The root appears cone shaped with a blunt apex. Unlike most other teeth, a line drawn through the center of the incisal edge will also cross through the center of the root apex. This also occurs in maxillary lateral incisors.The crest of curvature for the palatal and labial surfaces is located directly incisally to the cervical line. The labial surface of the crown is convex from the crest of curvature to the incisal edge. The lingual surface of the crown is convex near the cingulum and near the incisal edge, but for the most part is concave along the surface between those two areas.
More than any other tooth in the mouth, the cervical line from this view curves tremendously toward the incisal. In an average crown length of 10.5 to 11 mm, the curvature of the cervical line in a maxillary central incisor is 3 to 4 mm.
Distal view
The distal view of this tooth considers the portion of the tooth visible from the side furthest from where the middle line of the face would be. This side of the tooth is very similar to the mesial side. A greater portion of the tooth surface facing the lips is visible from this view compared to the mesial view because the labial surface tilts distally and lingually. Also, the cervical line curves less in comparison to the mesial view.Incisal view
The incisal view of this tooth considers the portion of the tooth visible from the side where the incisal edge is located. From this angle, only the crown of the tooth is visible, and overall the tooth looks bilateral. The labial surface appears broad and flat. The lingual surface tapers toward the cingulum. The distance between the mesioincisal angle to the cingulum is slightly longer than the distance between the distoincisal angle to the cingulum.Pulp anatomy
The pulpPulp (tooth)
The dental pulp is the part in the center of a tooth made up of living connective tissue and cells called odontoblasts.- Anatomy :Each person can have a total of up to 52 pulp organs, 32 in the permanent and 20 in the primary teeth....
is the location of the nerve and blood supply of a tooth. In the deciduous maxillary central incisor, endodontic
Endodontics
Endodontics is one of the dental specialties recognized by the American Dental Association, Royal College of Dentists of Canada, and Royal Australasian College of Dental Surgeons, and deals with the tooth pulp and the tissues surrounding the root of a tooth...
treatment is less frequent. In the permanent maxillary central incisor, root canal
Root canal
A root canal is the space within the root of a tooth. It is part of a naturally occurring space within a tooth that consists of the pulp chamber , the main canal, and more intricate anatomical branches that may connect the root canals to each other or to the surface of the root.-Root canal anatomy:...
treatment can be effective. There frequently are three pulp horns in this tooth. In nearly all maxillary central incisors, there is one canal with one apex. During root canal therapy, access into the pulp is frequently located centrally on the lingual surface between the incisal edge and the cingulum. At the level of the cervical line, the shape of the canal is triangular but becomes circular at the middle level of the root. Although the root is generally straight, the most common points of curvature is near the apex, and their direction is more common toward the distal and lingual.
Interproximal contacts
Mandibular central incisor
The mandibular central incisor is the tooth located on the jaw, adjacent to the midline of the face. It is mesial from both mandibular lateral incisors. As with all incisors, its function includes shearing or cutting food during mastication, commonly known as chewing. There are no cusps on the...
s. In usually preferred and healthy states, the central incisors touch in the incisal third of the teeth. On the other hand, the contact between the central incisor and the lateral incisor is nearer the gingiva at the location between the incisal and middle thirds of the tooth's crown.
Occlusion
As with all maxillary anterior teeth, the central incisors are usually located facially to the mandibular teeth when the mouth is closed. In instances when the maxillary anterior teeth are lingual to the mandibular teeth, the condition is referred to as an anterior crossbite. In some cases, this arrangement of teeth may indicate a displacement of the mandible relative to the maxilla and is called Class III or Pseudo-Class III malocclusionMalocclusion
A malocclusion is a misalignment of teeth or incorrect relation between the teeth of the two dental arches. The term was coined by Edward Angle, the "father of modern orthodontics", as a derivative of occlusion, which refers to the manner in which opposing teeth meet.-Presentation:Most people have...
. Normal occlusion is Class I occlusion.
When the teeth are biting down, the maxillary central incisors occlude with the mandibular central and lateral incisors. The contact point of the mandibular teeth is in the lingual fossa of the maxillary central incisor about 4 mm gingivally from the incisal edge. In this position, the maxillary incisors cover nearly half of the mandibular incisors' crowns. When the maxillary and mandibular incisors do not contact even when the mouth is fully closed, an anterior open bite occurs. This misalignment of teeth may result from some habits, such as thumb-sucking. On the other hand, when the contact of the mandibular incisors to the maxillary incisors is near or completely on the gingiva, a deep bite occurs.
Variation
Sinodonty, a genetic variation occurring in Native AmericansIndigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...
and some East Asian
Asian people
Asian people or Asiatic people is a term with multiple meanings that refers to people who descend from a portion of Asia's population.- Central Asia :...
populations, is possibly a trait
Trait
Trait may refer to:* Trait, a characteristic or property of some object* Trait , which involve genes and characteristics of organisms* Trait theory, an approach to the psychological study of personality...
retained from an indigenous East Asian archaic human ancestor Homo Erectus Pekinensis
Peking Man
Peking Man , Homo erectus pekinensis, is an example of Homo erectus. A group of fossil specimens was discovered in 1923-27 during excavations at Zhoukoudian near Beijing , China...
. Among its features are shovel-shaped incisors
Shovel-shaped incisors
Shovel-Shaped incisors: Incisors that have a scooped out lingual surface because of lingual marginal ridges, crown curvature, or a basal tubercle, either alone or in combination....
that derive their name from the deeper-than-normal lingual fossa and prominent marginal ridges of the teeth. When seen from lingual view, the tooth is said to resemble a shovel
Shovel
A shovel is a tool for digging, lifting, and moving bulk materials, such as soil, coal, gravel, snow, sand, or ore. Shovels are extremely common tools that are used extensively in agriculture, construction, and gardening....
and are rotated slightly inward. It is also common to see signs of attrition, which is wear over time from other tooth contact. The lingual of maxillary incisors and the facial of mandibular incisors are the most common places for attrition to occur.
When space exists between the contacts of the maxillary central incisors, the condition is referred to as a diastema
Diastema (dentistry)
Diastema is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars.-In humans:...
or "gap tooth." One frequent cause of the space is the presence of a large labial frenum
Frenulum
A frenulum is a small fold of tissue that secures or restricts the motion of a mobile organ in the body.-In human anatomy:...
from the upper lip extending near the teeth. Treatment depends upon the cause and extent of the gap. Periodontal surgery may be required to reduce the frenum. A small space may be corrected with a filling
Dental restoration
A dental restoration or dental filling is a dental restorative material used to restore the function, integrity and morphology of missing tooth structure. The structural loss typically results from caries or external trauma. It is also lost intentionally during tooth preparation to improve the...
, veneer
Veneer (dentistry)
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 protect a damaged tooth surface. There are two main types of material used to fabricate a veneer, composite and dental porcelain...
, or crown
Crown (dentistry)
A crown is a type of dental restoration which completely caps or encircles a tooth or dental implant. Crowns are often needed when a large cavity threatens the ongoing health of a tooth. They are typically bonded to the tooth using a dental cement. Crowns can be made from many materials, which...
. Larger spaces may require orthodontics.
The maxillary incisors, both the central and lateral, are the most likely teeth to have a talon cusp
Talon cusp
A talon cusp, also known as an "eagle's talon", is an extra cusp on an anterior tooth. The term refers to the same condition as dens evaginatus, but the talon cusp is the manifestation of dens evaginatus on anterior teeth. The incidence has been found to range from less than 1% to 6% of the...
, which is an extra cusp on the lingual surface. Talon cusps have been found in to range in less than 1% to 6% of the population, and 33% of cases occur on the permanent maxillary central incisor. Deciduous teeth are unlikely to have talon cusps. Also, the permanent maxillary incisors are the most likely teeth to have a dilaceration
Dilaceration
Dilaceration is a developmental disturbance in shape of teeth. It refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth.-Description:The condition is thought to be due to trauma during the period in which tooth is forming...
, which is a sharp curve on a tooth.
All incisors have the potential to be affected by a case of congentital syphilis
Syphilis
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...
, which can cause a notch to form on the incisal edges of these teeth. These teeth, sometimes described as screwdriver-shaped, are called "Hutchinson's incisors
Hutchinson's teeth
Hutchinson's teeth are a sign of congenital syphilis. Babies with this have teeth that are smaller and more widely spaced than normal and which have notches on their biting surfaces...
." They serve as part of Hutchinson's triad
Hutchinson's triad
Hutchinson's triad is named after Sir Jonathan Hutchinson . It is a common pattern of presentation for congenital syphilis, and consists of three phenomena: interstitial keratitis, Hutchinson incisors, and eighth nerve deafness.- References :...
, which also includes interstitial keratitis
Keratitis
Keratitis is a condition in which the eye's cornea, the front part of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves impaired eyesight.-Types:...
and eighth
Vestibulocochlear nerve
The vestibulocochlear nerve is the eighth of twelve cranial nerves, and is responsible for transmitting sound and equilibrium information from the inner ear to the brain...
nerve
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
deafness.