What is....?- 1

Source:  What is....?- 1    Tag:  intraoral periapical radiograph
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Accessory canals
During root formation, when there is a premature loss of root sheath cells or when the developing root encounter a blood vessels an opening or a connection is established between the radicular pulp and the periapical connective tissues. Such a connection is referred as accessory canals. These are common in apical third of the posterior teeth.
Acellular cementum
The cementum, common in the apical third of root, which does not consist of cementocytes is called as acellular cementum
Acid phosphatase
It is an enzyme associated with hard tissue destruction and mainly localized to the lysosomes of the osteoclasts. They are more commonly exhibited by an active cell in areas of hard tissue destruction.
Acinus
It is the terminal secretory end piece of any gland where the active ingredients of the secretions are synthesized and released.
Active eruption
It is the process or the movement of a normal tooth from its place of formation in the jaw bones to its place of function along the occlusal plane is called as active eruption.
Adherence junctions
Found below tight junctions and show a visible gap between adjacent cell membranes. No structures are found in this gap. The cellular side of adherens junctions contains a fine matting of fibrous material (microfilaments) which are embedded in dense plaques composed of myosin, tropomyosin, alpha-actinin, and vinculin.
Alkaline phosphatase
It is an enzyme associated with hard tissue formation or mineralization. They are capable of hydrolyzing phosphoric acid esters. Hence these enzymes readily supply the much required phosphate ion at the site of mineralization.
Alveolar bone
That part of jawbones provides the support for the teeth.
Alveolar bone fundus
Base of the alveolar socket
Alveolar bone proper
A thin lamella of bone that surrounds the root of the tooth and gives attachment to the principal fibers of the periodontal ligament is the alveolar bone proper.
Alveolar bone, supporting
The part of the alveolar bone that surrounds the alveolar bone proper and gives supports to the socket is the supporting alveolar bone.
Alveolar crest
It is the thin margin of the bone that surrounds the teeth
Alveolar crest fibers
It is one of the principal periodontal fibers that radiate from the crest of the alveolar process to the cervical part of the cementum.
Alveolus
It is that part of jawbones in which the teeth are embedded.
Amelin
It is an enamel protein constituting about 5 to 10% of all enamel proteins. They play a role in crystal growth.
Ameloblasts
The enamel forming cells derived from ectoderm, which differentiates from the inner enamel epithelium of the enamel organ.
Amelogenesis
The process of formation of enamel is called as amelogenesis
Amelogenins
Of all the enamel proteins, 90% of them belonged to a heterogeneous group of gene- specific, low molecular low weight proteins called as Amelogenins.
Amylase
Enzymes present in saliva those catalyses the hydrolysis of starch in to smaller water soluble carbohydrates.  Also known as salivary amylase
Anatomic repair
When a damaged root surface is repaired by the reestablishing the former out line by cementum formation it is called as anatomic repair
Anatomical crown
The part of the crown that extends from the occlusal or incisal surface to the cervical line is the anatomical crown.
Anchoring fibrils
These Type VII collagen fibrils are found in the basement membrane and provide a mechanical attachment for the epithelium with the underlying connective tissue.
Annexins
Calcium binding proteins that interact with acid phospholipids in membranes. Examples are lipocortins, endonexins.
Apatite crystals
The inorganic constituent of any biological mineralized tissue is a calcium phosphate salt approximating in to a crystal structure referred as the apaite or hydroxyapatite crystals.
Apical cementum
Cementum deposited on the apical region of the root.
Apical fibers
It is one of the principal periodontal fibers that radiate from the apex of the teeth to the alveolus.
Apical foramen
The radicular pulp is continuous with periapical connective tissues through a small opening at the tip or the apex called as the apical foramen
Apposition
 It is the process of deposition of the matrix of the hard dental tissues
Aquaporin
Group of homologous integral membrane water channel proteins expressed in fluid transporting epithelia. Modulate the osmolority of fluids in salivary glands.
Articular disk
It is an extension of the fibrous capsule of the tempromandibular joint in to the joint cavity dividing the joint in to 2 compartments – the upper and lower compartments. It provides an articular surface for the head of the condyle.
Articular eminence
It is the prominence of the temporal bone anterior to the tempromandibular joint.
Attached Gingiva
The part of the gingiva that firmly attaches to alveolar process.
Basal lamina
It is the electron microscopic appearance of the basement membrane that separates the epithelium and the underlying connective tissue. It consists of three layers – two layers of lamina densa separated by a lamina lucida and the anchoring fibrils below.
Basal layer
The layer of the epithelium that is closest to the connective tissue. It provides the epithelial stem cells as well as cells to supplement the epithelial differentiation.
Basement membrane
It is the light microscopic appearance of the basal lamina. It appears as a thin demarcation separating the epithelium and connective tissues. It answers positive with a magenta color with PAS reagent staining.
Bone Morphogenetic Proteins
Transforming growth factor- beta group of proteins; Can induce bone/cartilage formation; Plays a vital role in tooth formation
Bone Morphogenic protein
These are a heterogeneous group of proteins that are responsible for the proper initiation, formation, development, maturation and calcification of hard tissues.
Bone sialoprotein
These are a heterogeneous group of non-collagenous proteins that are responsible for the proper calcification of hard tissues. They probably function as a nucleator of calcification.
Buccopharyngeal membrane
This membrane separates the stomatodeum from the primitive pharynx (cranial part of the foregut). This membrane ruptures at 24 to 26 days and communication with the amniotic cavity is established.
Bud stage
Initial stage of tooth development; gives rise to enamel organ
Bundle bone
The part of the alveolar bone proper, which has the bundles of the principal fibers of periodontal ligament, continues in to this bone as Sharpey’s fibers.
Burtonian line
Lead and bismuth in high quantities produce exogenous pigmentation along the gingival margins as bluish black-to-black lines called as Burtonian lines. The color is due to the formation of metallic sulphide, the sulphide radical derived from the bacterial sources.
Cadehrins
It is a calcium dependent transmembrane protein that helps in the attachment of cells to the extracellular matrix. They belong to the integrin family of proteins.
Calciotraumatic line
A type of incremental line of dentin separating secondary and reparative dentin
Calcospherites
The globular zones of mineralization in any hard tissues are referred as calcospherites.
calculus, dental
Hard calcified plaque.
Calvaraia
Skull cup
Cambium layer
The osteogenic cellular layer of the periosteum in a sutural bone is referred as the cambium layer. They play a vital role in the growth of the sutural bones.
cAMP or Cyclic AMP
 Second or intracellular messenger of target cells.
Canaliculi, Bone
Small microscopic space that have cellular projection of osteocytes
Canaliculi, Cementum
Small microscopic space that have cellular projection of cementocytes
Canaliculi, Dental
Space occupied by branches of dentinal tubule
Cancellous bone
A network of bony trabeculae called as the cancellous or spongy bone interrupts the bone marrow cavity.
Cartilage
Calcified connective tissue characterized by non-vascularity and firm in consistency. three types - hyalin, fibroelastic, elastic
Cell Differentiation
An increase in morphologic/chemical heterogeneity
Cell free zone
This is a layer found in the pulp just adjacent to the odontoblastic layer and is a space in which the odontoblast move pulp ward during new dentin formation.
Cell proliferation
Developmental process in which cell undergoes cell cycle dividing in to two daughter cells, leading to increase in number of cells
Cell rests. Malassez
Epithelium remnants of root sheath in periodontal ligament
Cell rich zone
This is a layer of pulp below the cell rich zone. It is made up of numerous fibroblasts, collagen, fibers, undifferentiated mesenchymal cells and inflammatory cells
Cellular cementum
The cementum, common in the apical third of root, which consists of cementocytes is called as cellular cementum
Cementicles
Calcified spherical cemental bodies, free/ attached or embedded
Cementoblasts
The cementum forming cells derived from the ectomesenchymal dental sac cells.
Cementocytes
The cementoblasts that get entrapped in the cementum it forms and is a resting cell is called as cementocytes.
Cementodentinal junction
The relatively smooth surface where dentin and cementum meets is separated by a type of cementum called as the intermediate type of cementum.
Cementoenamel junction
The relationship of cementum and enamel at the cervical region is called as the cementoenamel junction. The cementum overlaps enamel (60%) or meet at sharp point(30%) or does not meet at all(10%).
Cementoid tissue
The uncalcified matrix of cementum is called as cementoid tissue
Cementum
The ectomesenchymal derived mineralized dental tissue that covers the anatomical roots of a human tooth.
Cervical line
The junction of the cementum and enamel is marked by a demarcating line called cervical line
cervical loop
Growing free border of enamel organ. The outer& inner enamel epithelial layers continously divided deeper and lead to formation of root.
Cervical loop
See epithelial diaphragm
Choanae
 Paired openings between nasal cavity and nasopharynx.
Chondrocranium
 embryonic skull before ossiifcation; Cartilageonous skull
Cingulum
Lingual lobe of anterior teeth
Circular collagen fibers
This is a small group of the gingival fibers that form a band around the neck of the tooth, interlacing with other group of fibers in the free gingiva and helping free gingiva to bind to the tooth.
Circumpulpal dentin
 It is that part of primary dentin that encircles the pulp chamber and does not include the mantle dentin
Circumvallate papillae
Adjacent and anterior to the sulcus terminalis there are about 8 to 12 large papillary structures surrounded by a deep circular groove where the minor serous salivary glands (of von Ebner) are located along with taste buds.
Clinical crown
The part of the anatomical crown that is visible in the oral cavity is called as the clinical crown.
Col
The interdental gingiva has an outline of a depression with the buccal and lingual interdental papilla at the ends. This depression is just below the contact point and is called as the col.
Collagen
 White fibers of the connective tissue, composed of fibers, fibrils and interfibrillar cement
Collagen
Collagens are the major heterogenous group of fibrous proteins found in the extracellular matrix
Compact bone
 Hard, external calcified cancellous portion of bone
Contour lines of Owen
These contour lines results from incremental daily deposition of dentin along the secondary curvatures of dentinal tubules.
Coronal pulp
The pulp in the crown of  teeth
Cribriform
 Bone containing perforation/foramina
Cribriform plate
The bone lining the tooth socket, the bundle bone, is perforated by many foramina that transmits nerves and vessels and hence called as the cribriform plate.
Crown, anatomical
 The portion of crown that is from cervical line to cusp/incisal ridge
crown, Clinical
 The portion of crown that is visible in the oral cavity
Crypts
 Pit like depressions
Cuff epithelium
During eruption, the cells of outer layers of reduced enamel epithelium and the basal layers of oral epithelium proliferate to form a mass of epithelium. The teeth emerge through the selective apoptosis of this epithelium and this epithelium plays a role in establishment of the primary epithelial attachment of teeth to the periodontal tissues.
Cusp
Is an elevation on the crown portion making up a occlusal part
Cytodifferentiation
 The process by which an undifferentiated cell attains more differentiation phenotype
Cytoskeleton
Each cell needs a internal framework to provide support, facilitate intracellular transport and permit motility called the cytoskeleton. This cytoskeleton is made up of microtubules and filaments.
Dead tracts
They are the dentinal tubules where the odontoblastic process has disintegrated due to noxious stimuli and subsequently filled with air. They appear black in transmitted light and white in reflected light under dried ground section.
Decorin
One of an important proteoglycan found in association with collagen fibrils as “decorations” and regulates the growth of the collagen fibrils.
Demilune
 Crescent shaped serous cells in a mixed gland that has a cap over the ends of a mucous acinar cells.
Demilunes
In a mixed salivary gland the tubular mucous salivary acini is often capped by a resent shaped seromucous cells called as  the demilune that discharge their contents in to the tubular end piee.
Dental lamina
Horseshoe shaped epithelial bands that transverse the upper& lower jaw and give rise to ectodermal portion of tooth
Dental Papilla
 formative organ of dentin and pulp
Dental papilla
 Dental papilla is the ectomesenchymal tissue condensations that immediately sub adjacent to the enamel organ and gives rise to the dentin and pulp.
Dental sac
 Is the sac like ectomesenchymal thickening surrounding the enamel organ and dental papilla. In latter stages, it gives rise to the fibrous attachment apparatus of the teeth and cementum.
Dentary bones
These are the lower jawbones of the lower vertebrates that bear the tooth.
Denticles
These are the discrete calcified masses found in the pulp tissue. These are concentric layers of mineralized tissues formed by surface accretion around a thrombi, dying or dead cell or around a collagen fiber. They may be free (free denticles) or attached to dentin (attached denticle). If the calcified masses may resemble the dentin (true denticles) or remain as a structureless calcified mass (false denticles).
Dentin
The ectomesenchymal derived mineralized dental tissue that forms the bulk of the crown and root and lies beneath the enamel in anatomical crown and cementum in anatomical root in a human tooth.
Dentin Phosphoprotein
 See Phosphoryn
Dentin Sialoprotein
A phosphorylated, highly glycosylated protein with high amounts of sialic acid
Dentinal fluid
The fluid that is found within the dentinal tubules is known as the dentinal fluid
Dentinal lymph
See dentinal fluid
Dentinoenamel junction
It is a hypocalcified structure representing the junction of the dentin and enamel, which is scalloped to facilitate increased surface area of contact.
Dentinogenesis
The process of formation of dentin by the odontoblasts is called as dentinogenesis.
Dentogingival collagen fibers
These are one of the major groups of gingival fibers that extend from the cervical cementum in to the lamina propria. It is the most numerous group of gingival fibers.
Dentoperiosteal group of fibers
These are one of the major groups of gingival fibers that extends from the cervical cementum in to the periosteum of the alveolar crest, vestibular surface and oral surface of the alveolar bone.
Desmoplakin
The attachment plaque made of protein found only in desmosomes is the desmoplakin.
Desmosomes
 A junction in which adjacent cell membranes are visibly separated and filled with dense fibrous material. An electron dense layer lines the cytoplasmic face of desmosomes in which are embedded an abundance of fibers made up of the proteins described above for zonula adherens junctions as well as intermediate filaments such as keratin.
Developmental grooves
 Shallow grooves that separate cusps or primary parts of teeth
Dichophase
The stage of cell division of a basal epithelial cell when it decides to either differentiate or divide is called as the dichophase.
Differentiation
Growth associated with distinguishing character/function from adjacent structures from original type/specialization
Diffuse calcifications
This is a structure formed as a result of regressive change of pulp where there is a calcification in the pulp that appear as irregular calcification deposits in the pulp tissues.
Diphyodont
Two sets of teeth
Ducts
The tubular elements of the exocrine glands that forms a pathway through which the secretions are taken to the site where the secretion is discharged.
Dystrophy
Disorder arising from defective or faulty nutrition
Ectochondral Bone
Type of bone formation within cartilage and replacing it
Enamel
The ectodermal derived mineralized dental tissue covers the anatomical crown of a human tooth.
Enamel cord
Epithelial proliferation that seems to divide the dental organ in two.
Enamel Knot
Collection of epithelial cells associated with inner enamel epithelium of the enamel organ. A transient structure responsible for producing signaling molecules.
Enamel knot
Thickening of the internal dental epithelium at the center of the dental organ. `
Enamel lamellae
These are thin leaf like hypocalcified structures seen in enamel arising in planes of tension. They arise from the enamel surface extending towards the dentinoenamel junction.
Enamel niche
It is an artifact that is produced during section of the tissue. It occurs because the dental organ is a sheet of proliferating cells rather than a single strand. It looks like a concavity that contains ectomesenchyme.
Enamel organ
Are small knob like structure arising from dental lamina that represents initiation of teeth development and gives rise to the enamel
Enamel rod
Each enamel rod has a cylinder-like shape and is composed of crystals that run parallel to the longitudinal axis of the rod. At the periphery of the rod, the crystals flare laterally.
Enamel spindles
These are extension of the odontoblastic process extending in to the enamel.
Enamel tufts
They are the grass like appearing hypocalcified structures of enamel arising at dentinoenamel junction and extending till one third of enamel thickness. They probably appear due to abrupt change in direction of enamel rods at the dentinoenamel junction.
Enamelcord
A structure connecting enamel knot to enamel niche
Enamelin
An acidic glycosylated phosphoprotein of mature enamel.
Entactin
An extracellular matix glycoprotein associated with basal lamina
Epithelial diaphragm
Hertwig’s epithelial root sheath bend at the future cementoenamel junction in to a horizontal plane.
Epithelium
Cellular, avascular layer covering all the free surface of the body - internal/external & lining of vessels.
Epithelium, inner enamel
The cells that line the concavity of the enamel organ in the cap/early bell and differentiates in to ameloblast to give rise to enamel
Epithelium, Outer enamel
Cuboidal peripheral cells of the cap/bell stage of tooth development that lines the convexity of the cap
Eruptive tooth movements
The tooth movements that accompany a tooth bud when it moves its place of formation to its place of function is called as the eruptive tooth movements.
Extracellular Matrix
 Macromolecular products of mesenchymal and epithelial (rarely, as in basement membrane components) cells that provide a role in cellular adhesion
Extrinsic fibers of cementum
The collagen fibers embedded in the cementum that arises by the incorporation of the periodontal ligament fibers. 
False dentin
This is a structure formed as a result of regressive change of pulp where there is a calcification in the pulp with the structure not resembling dentin.
Fibrils
The subunits of fibers. Each fibril is formed by packing of individual molecules. For example, tropocollagen molecules condense to form collagen fibril.
Fibronectins
Are protein molecules associated with fibroblast. They polymerize to form pericellular matrices and mediate binding of one connective tissue cell, especially fibroblast to others. Plays a major role in eruption of teeth & associated with periodontal traction theory.
Fibronexus
The connection between the Sharpey’s fibers and fibroblast, cemented by a protein called fibronectin. The area of this cementation is refereed as fibronexus. Also found in many other situations in connective tissue, especially where two cells is adhered through the fibronectin. 
Filiform papillae
On the anterior, dorsal part of the tongue, there are numerous, fine pointed cone shaped epithelial structures with a core of connective tissue that gives the tongue velvet like appearance and lacks taste buds.
Foliate papillae
In the posterior lateral surface of tongue, sharp parallel clefts, contains the foliate papilla which contains taste buds. It is said to be a vestigial organ.
Fontanelles
 One of several membranous intervals at the angles of cranial bones in an infant. there are six fontanelles - corresponding to pterion, asterion (on both side) as bregma and lambda in the midline
Fossa
Depression or concavity in any surface of crown
Free nerve endings
Sensory receptor for pain
Functional repair
When a damaged root surface is repaired by the reestablishing the former out line by bone formation that fits in to the damaged area it is called as functional repair.
Fungiform papillae
In the anterior dorsal surface of tongue, interspersed between the filiform papillae are isolated, fungi like appearing, reddish prominences with one to three taste buds.
Furcation
 An anatomic multi-rooted tooth where the roots divide
G protein
 Guanosine 5-triphosphate binding regulatory protein that alters an intracellular messenger
Gap junctions
Junctions in which direct cell-cell communication can occur through small pore structures called connexons. As an example, heart muscle contraction is coordinated in part through cell-cell communication across gap junctions.
Gingiva
The soft tissue covering the root, alveolar bone extending from dentogingival junction to the alveolar mucosa.
Gingival sulcus
Or the Gingival crevice is the space between the inner aspect of the gingival and the tooth.
Glands of von Ebner
The minor serous salivary gland situated in the trough of the circumvalate papillae. 
Glycosaminoglycans
Glycosaminoglycans are polymers of repeating disaccharide units constructed of hexosamine and carboxylate or sulfate ester.
Gnarled enamel
 Optical phenomenon produced by abrupt changes in rod direction and twisting of rods around each other over the cusps of teeth.
Gomphosis
The type of joint between 2 calcified structures through a soft tissue
Gubernacular canals
In the coronal part of the developing permanent teeth (except molars) in the alveolar crypt, bone surrounds the tooth germ along with a small canal, the gubernacular canal and filled with remnants of  dental lamina and connective tissue, forming the gubernacular cords. This cords is believed to guide the permanent tooth as it erupts.
Gubernacular cords
In the coronal part of the developing permanent teeth (except molars) in the alveolar crypt, bone surrounds the tooth germ along with a small canal, the gubernacular canal and filled with remnants of  dental lamina and connective tissue, forming the gubernacular cords. This cords is believed to guide the permanent tooth as it erupts.
Haversian canal
A part of functional and basic metabolic unit of bone, the osteon. The concentric circumferential lamellae has  a central vascular canal called the Haversian Canal
Hemidesmosomes
 A special type of desmosomal junction occurring between basal epithelial cells to the underlying extracellular matrix
Hertwig’s epithelial root sheath
The fusion of the inner and outer enamel epithelium after completion of enamel secretion produces this layer that is responsible for the development of root
Heterogenous mineralization
The process of mineralization which does not occur uniformly throughout the tissue
Heterogenous nucleation
The process of mineralization where the seeding or initiation of mineralization does not occur uniformly throughout the tissue.
Histodifferentiation
A process by which cells undergoes definitive morphologic as well as functional changes and acquire their functional assignment accompanied by loss of ability to multiply.
Homogenous nucleation
The process of mineralization which occur uniformly throughout the tissue
Horizontal collagen fibers
A type of periodontal fibers that run horizontally from the cementum to the alveolar bone. Mostly found in the center part of the root
Howship’s lacunae
The area of resorption associated with the osteoclast in bone is irregular with a scalloped outline called Howship’s lacunae.
Hunter -Schreger bands
These are alternating dark and light bands of varying width, best seen in longitudinal sections. They appear due to the change in direction of rods and is considered to be a functional adaptation
Hyaline layer of Hopewell smith
Along the Cementodentinal Junction in apical third of posterior tooth, a small band that neither appears to be  cementum or dentin and is structure less, called the hyaline layer or the Intermediate cementum
Imbrication
Fine Striations in the dentin; Also called as Striae of Von Ebner
Incal cartilage
A part of the Meckel’s cartilage that persists to form the Incus.
Inner enamel epithelium
The tall columnar cells that line the concave surface of the cap stage of tooth development. It undergoes histodifferentiation to become ameloblasts and secretes enamel.
Integrins
A group of cell surface proteins that mediate the binding of cells to extracellular matrix proteins to one another.
Intercalated ducts
The single layered structures made of a low cuboid  cells found between the salivary secretor units that conduit saliva but also contribute to macromolecular components.
Interglobular dentin
Zones of hypomineralization between the globules of calcification in dentin
Interlobular Duct
Channels located outside lobes of salivary glands
Intermediate cementum
Along the Cementodentinal Junction in apical third of posterior tooth, a small band that neither appears to be  cementum or dentin and is structure less, called the hyaline layer or the Intermediate cementum
Interradicular collagen fiber
The group of periodontal fiber that runs between the two roots
Intertubular dentin
It is that part of the dentin that lies between the dentinal tubules and is the main body of dentin
Intralobular duct
Channels locatyed within lobes of salivary glands
Intramembranous bone growth
The direct formation of bone within highly vascularized sheets of condensed primitive mesenchyme.
Intratubular dentin
The dentin that immediately surrounds the dentinal tubules. As the deposition of dentinal tubules occurs in the inner wall of the tubule, it is preferred term. Also known as the peritubular dentin. 
Intrinsic fibers of cementum
The collagen fibers embedded in the cementum that arises from the cementoblastic activity.
Irregular secondary dentin
See tertiary dentin
Junctional epithelium
Junction of the tooth and gingival epithelium. The union between this epithelium and tooth is the epithelial attachment
Keratinization
The total sum of changes in metabolical, morphological and biochemical changes that occurs when the cells of mucosa moves from basal layer to the superior most layer is called as keratinization
Keratinocytes
The cells that undergo the keratinization
Keratins
The product of Keratinization,
Keratohyaline granules
In the stratum granulosum in the keratinized mucosa contains small organelle that are highly hematxophillic and secrete the keratin. They are also called as Keratinosome, Odland bodies, membrane coating granules. 
Krause end bulbs
Sensory receptor for cold
Krause’s bulb
Fine nerve endings associated with pressure/tactile sensation
Kroff’s fibers
These are argyrophilic ground substances. Earlier they were thought to be collagen fibers formed among odontoblasts.
Lamellae of bone
The sequence of concentric or parallel deposition that forms the bulk of bone
Lamellate granules
Lamellar granules found in stratum granulosum discharge their contents in to intercellular space forming a permeability barrier.
Lamina densa
An electron microscopic feature of Basement membrane, Basal Lamina, it is the dense portion that is found in the basal lamina
Lamina dura
The thin radiopaque line in the intraoral oral periapical radiographs of the tooth, which indicates the bundle bone surrounding the tooth just next to the cementum.
Lamina limitans
It is the inner organic lining of the calcified dentinal tubule wall.
Lamina lucida
An electron microscopic structure in basal lamina indicating a electron rare region between lamina densa and the anchoring fibrils
Lamina propria
The connective tissue component of oral mucosa
Lamina splendens
The fibrous layer covering condyle is lined by a vascular fibrous connective tissue
Laminins
They are the group of extracellular glycoproteins involved several vital functions including communication, defense and attachment. Produced in general by epithelial cells. Major constituent of basal lamina, interacts with type IV collagen
Langerhan’s cell
The dendritic, non-keratinocyte, high level clear cell of the oral mucosa that is an antigen presenting cells. A major player in immune system
Lectins
Groups of cell surface proteins.
Lining mucosa
The mucosa that lines the oral cavity
Loricrin
Sulphur rich component of the keratohyaline granules
Macula adherens
See adherence junctions
Macula occludens
See tight junctions
Malassez, cell rests
Remnants of the Epithelial Hertiwgs Sheath
Mantle dentin
 The outermost layer of primary dentin formed by the newly differentiated odontoblast and lacks phosphophoryn.
Marginal Ridge
Ridge or elevation of enamel forming the margin of the surface of a tooth; specifically, mesial &distal of occlusal surfaces posterior teeth & mesial /distal margins of lingual surfaces anterior teeth
Masticatory mucosa
The type of mucosa that is exposed to stress and strain of mastication. It is the mucosa that covers the palate, alveolar mucosa.
Meckel's cartilage
 It is the 1st branchial arch cartilage. It does not form the mandible but indicates the position of the future mandible.
Meissners corpuscles
Sensory receptor for touch
Melanin
An endogenous pigment
Melanocyte
The melanin producing cells, a non-keratinocyte in epithelium and a low level clear cell
Melanophage
The macrophages that accumulate the melanin when there is a spill of melanin
Melanosomes
Melanin produced by melnocyte are transferred through their dentritic process to basal keratinocyte that stores in the form of melanosomess
Membrana preformitiva
The basement membrane that separates the enamel organ and dental papilla just prior to dentin formation
Membrane Preformativum
 Basement membrane separating enamel organ and dental papilla preceeding dentin formation.
Merocrine
 Type of glandular secretion in which secreting cells remains intact during formation and relase of secretory products
Metalloproteinases
The group of enzymes those are associated with the breakdown of connective tissue fibers and matrix. These enzymes break down the ground substance, matrix as well as fibers so remodeling can occurs
Microfibrils
Smaller units of fibrils
Morphodifferentiation
A process by which the ameloblasts establish the basic form and relative size of teeth by differential growth
Mucopolysaccharides
 previously known as Glycosaminoglycans
Muscularis Mucosae
Intervening layer of smooth muscles and elastic fibers between lamina propria and submuosa in intestinal mucosa
Nasmyth’s membrane
 It is a delicate membrane that covers the newly erupted crown of the teeth and rapidly removed due to mastication. It is believed to be basement membrane in origin.
Neonatal line or ring
 An accentuated incremental line seen in the enamel and dentin of the deciduous teeth between the hard tissues that is formed before and after birth due to abrupt change in environment and nutrition
Neural fold
Neural groove
Neural plate
Neural tube
Neuropores
Appearance of the notochord and prechordal mesoderm induces the overlying ectoderm to thicken and form the neural plate. Cells of the plate make up the neuroectoderm and their induction represents the initial event in the process of neurulation. Once neural induction has occurred, the elongated, slipper-shaped neural plates expand toward the primitive streak. By the end of the third week, the lateral edges of the neural plate become more elevated to form neural folds, and the depressed midregion forms the neural groove. Gradually, the neural folds approach each other in the midline, where they fuse. This fusion begins in the cervical region (fifth somite) and proceeds cranially and caudally. As a result, the neural tube is formed. Until fusion is complete, the cephalic and caudal ends of the neural tube communicate with the amniotic cavity by way of the cranial and caudal neuropores, respectively.
Nidogen
also called entactin is a rod-shaped protein consisting of a single polypeptide chain. Nidogen binds with high affinity to collagen IV and laminin, it has an organ izing role in assembly of the basal lamina. Nidogen also binds perlecan, the large heparan sulfate proteoglycan of the basal lamina. The coexpression of laminin 1 and nidogen results in a relatively stable basal lamina. Laminin is produced by epithelial cells and nidogen is secreated by mesenchymal cells.
Non-keratinocytes
The non-epithelial cells found in the layers of stratified squamous surface epithelium
Oblique collagen fibers
The group of periodontal and gingival fibers that run obliquely
Oblique Ridge
The ridge that extends from the mesiopalatal cusp to the distobuccal  cusp as seen in permanent maxillary first molars
Odontoblastic process
The cytoplasmic extension of the odontoblasts
Odontoblasts
The dentin forming cells derived from the ectomesenchymal dental papilla cells.
Odontoclasts
The cells responsible for removal of calcified parts of the tooth
Olfactory bulbs
Sensory organelles responsible for olfaction, ie sense of smell
Oncocytes
These cells are associated with salivary glands. They are strongly eosinophilic because of their very high concentration of rnitochondria. They are present in small numbers in secretory endpieces and ducts. Oncocytes increase in number with age.
Oropharyngeal membrane
See buccopharyngeal membrane
Orthokeratinization
Loss of nucleus in process of keratinization in the superficial cells
Osteoblasts
The bone forming cells
Osteoclasts
The bone resorbing cells
Osteocytes
The osteoblasts that are entrapped in its own matrix. They are viable and is said to be a resting osteoblasts
Osteodentin
 When the cells forming the tertiary dentin is trapped with in it, it is referred as osteodentin
Osteogenesis
Formation of bone
Osteoid
The newly secreted bone matrix that is not calcified
Outer enamel epithelium
 The peripheral cells of the enamel organ in the cap and bell stage that are cuboidal and lie in the convexity or the outer surface of the teeth surface.
Parakeratinization
Presence of pynknotic nucleus and remnants in the process of keratinization in superficial cells
Parietal layer of nerves
See plexus of Rashkow
Pellicle
 It is a membrane formed on the surface of enamel by the precipitate of the salivary proteins. When colonized by microorganism it is becomes the pathological plaque.
Perikymata
These are transverse wave like grooves on the surface of enamel and believed to be the external manifestation of striae of Retzius
Peritubular dentin
It is that part of the dentin that immediately surrounds the dentinal tubules.
Perivascular cells
The cells that are found in vincity of vascular channels
Permanent dentition
The dentition that replaces the primary dentition
Pharyngeal tonsil
 Lymphoid aggregation in the posterior wall of nasopharynx. Also known as Luschka's tonsil or third tonsil.
Phosphoryn
 A highly phosphorylated protein found in dentinal matrix
Pit
Small pinpoint depression found in fossa
Plaque
A complex microbiological ecosystem formed by the accumulation and colonization of oral microbes of the salivary pellicle
Plexus of Rashkow
In the pulp, there is a network of peripheral axons of nerves adjacent to cell rich zone. This layer is called as the plexus of Rashkow.
Predentin
 The recently secreted or formed dentin is located adjacent to the pulp tissue and is not mineralized.
Prickle cell layer
See stratum spinosum
Primary cementum
The cementum formed in the teeth before it reaches its place of its function
Primary curvature of dentin
 This is the S shaped course of the dentinal tubules formed due to the overcrowding of the odontoblasts as they retreat pulpally.
Primary dentin
 It is the dentin that is formed before root formation is completed. It makes the bulk of the dentin and outlines the pulp chamber.
Primary enamel cuticle
See Nasmyth’s membrane
Prisms, enamel
See Enamel rod, alternate name
Procollagen
The newly secreted collagen molecule that needs to undergo post-transitional modification to become collagen
Procollagen peptidase
The enzyme that are involved in modifying procollagen to collagen
Procollagenase
Serves as a part of the major pathway for activation of matrix metalloproteinases that helps in remodeling of connective tissue. Prostromelysin and procollagenase are secreted as inactive forms that are proteolitically activated by plasmin. Plasmin is generated from plasminogen by the action of plasminogen activator (PA). Urokinase PA, associated with the cell surface, activates matrix metalloproteinases in the immediate vicinity of the cell. Tissue
Proteoglycans
Glycosaminoglycan chains link covalently with core proteins to form proteoglycans.
Pulp
The ectomesenchymal derived soft tissues made up of odontoblasts, fibroblasts, collagen, fibers, undifferentiated mesenchymal cells and inflammatory cells. It occupies the innermost portion of the human teeth.
Pulp canal 
It is the space occupied by the pulp in the root
Pulp chamber
It is the space occupied by the pulp in the crown
Pulp horn
The thin extension of pulp towards the superficial occlusal/incisal part of the tooth
Pulp space
The space occupied by pulp
Pulp stones
The calcified masses present in the pulp. 
Pulp stones, Attached
The type of pulp stones attached to the dentinal walls.
Pulp stones, embedded
 Small calcified masses of dentin that protrude from dentin in to pulp. Also known as embedded pulp stones
Radicular pulp
The pulp found in the root of teeth
Reactive dentin
See tertiary dentin
Reciprocal induction
The phenomenon by which the cell signals of the epithelium and primitive ectomesenchyme mutually initiate and regulate the formation and differentiation of specialized structures such as enamel, dentin and cementum
Reduced enamel epithelium
Post-functional, by the collapse of the stratum intermedium and stellate reticulum, the ameloblast and the outer enamel epithelium combine to form the reduced enamel epithelium that would serve to protect the newly formed enamel. A part of the reduced enamel epithelium forms the future junctional epithelium
Reichert's cartilage
 It is the 2nd branchial arch cartilage, which forms the stapes, styloid process, and superior hyoid bone.
Remodeling
The phenomena by which the old bone is removed and new bone is deposited.
Reparative dentin
See tertiary dentin
Resting lines
The regular line that denotes the period of rest during formation of bones.
Rests of Malassez
 The epithelial remnants of Hertwig’s epithelial root sheath usually in the gingiva and periodontal ligament fibers
Retepegs
They are the finger like projection of the epithelium in to the lamina propria
Reteridges
They are the finger like projection of the connective tissue in to the epithelium
Reticulin
A basement membrane protein
Reversal lines
The basophilc cement line with little or no collagen & high in glycoprotiens and proteoglycans that marks the limit of bone erosion prior to formation of osteon is the reversal libe
Rhombomeres
Much of the face is derived from neural crest cells that migrate into the pharyngeal arches from the edges of the cranial neural folds. In the hindbrain, crest cells originate from segmented regions known as rhombomeres. There are eight of these segments in the hindbrain (R1 to R8), and crest cells from specific segments populate specific arches. Crest cells from R1 and R2 migrate to the first arch, cells from R4 go to the second arch, those from R6 and 7 to the third arch, and those from R8 to the fourth and sixth arches. In addition, the first arch receives crest cells originating in the midbrain. Few if any crest cells form from R3 and R5. Most of the cells from these rhombomeres undergo cell death by apoptosis, while a few migrate with crest cells originating from adjacent segments.
Ridge
Linear elevation on any surface of tooth named for their location
Ruffini’s corpuscles
Principal Sensory mechanoreceptors
Saliva
The secretion of salivary gland
Salivary calculi
The calcification of the plaque that is observed in clinically exposed area of the oral cavity. Also called as supragingival calculus
Salivary pellicle
It is the deposition of the complex polysaccharides, proteins and glycoproteins of saliva over the tooth surface along with the food debris
Sclerotic dentin
Mild chronic stimuli induce collagen fibers and apatite crystals formation in dentinal tubules occluding it. As the refractive index becomes equalized, it turns transparent and this event is common in older individuals.
Secondary cementum
The cementum formed in the teeth after it reaches its place of its function
Secondary curvature of dentin
 Smaller oscillations in the primary curvature of dentin is reffered as the secondary curvature of dentin tubules
Secondary dentin
It is the dentin that is formed after the root formation has been completed.
Secondary dentition
The second set of teeth that follows the primary dentition.
Secondary physiologic dentin
The dentin that is formed after the completion of crown.
Serous glands
The glands whose secretion is thin and watery
Sharpey’s fibers
The projection of collagen fibers in to the cementum is called as Sharpey’s fibers.
Specialized mucosa
The type of mucosa that has been evolved to undertake a specific function. For example tongue for taste perception.
Spongy bone
Cancellous bone that has a honeycomb appearance with large marrow cavities and sheets of trabecular bones
Squames
Fully cornified dead cells that are formed in the epidermis, hard palate, and oral gingival epithelium
Statherins
A salivary protein responsible for remineralization of enamel
Stellate reticulum
 The polygonal cells beneath the outer enamel epithelium with higher concentration of intercellular fluid and albumin. Seen only in cap and bell stage of tooth development.
Stomatodeum
 Refers to the primitive mouth that appears as a small depression in the early embryo
Stratum basale
The inner most layer of the stratified epithelium. Has got tall columnar cells that can divide or differentiate to form the mucsoa
Stratum corneum
The outer most layer of the stratified epithelium. Rich in keratin.
Stratum distendum
The layer in the non keratinized epithelium that is also referred as “stratum distendum” is the startum superficial as it lacks filligrin.
Stratum germinativum
The other name for stratum Basale and parabasal spinous cell layer.
Stratum granulosum
The layer of stratified epithelium just above the prickle cell layer or the stratum spinosum.  Contains cells that are larger and flater. Contain large number of basophilic keratohyaline granules and nucleus shows evidence of degeneration and pyknosis.
Stratum intermedium
 A layer formed during bell stage of teeth development between inner enamel epithelium and stellate reticulum with high degree of metabolic activity.
Stratum lucidum
A layer of mucosa in skin.
Stratum spinosum
The layer of stratified epithelium just above the stratum basale. Made up of irregular polyhedral committed to differentiation epithelial cells. Also known as prickle cell layer
Stratum superficiale
The layer of stratified epithelium at the top or the outer most layer of epithelium from the connective tissue. Imparts rigidity as well as the first line of protection
Striae of Retzius
 These represent the incremental pattern or the successive apposition of layers of enamel during crown formation.
Striae of von Ebner
See Imbrication Lines
Striated ducts
The ducts that connect the intercalated ducts and the excretory ducts. Largest portion of this system and made up of tall columnar epithelium with large amount of mitochondria
Stromelysin
It is a matrix metalloproteinase III. Stromelysins attack proteoglycans, elastin, fibronectin, laminin , and collagen types IV, V, IX, and X.
Submucosa
The layer that is found just below the mucosa
Successional lamina
 The lingual extension of the dental lamina from which permanent dentition arises. Develops from fifth month in vitro to tenth month of age
Sulcular epithelium
The non-keratinized epithelium that lines the sulcus of the gingival crevice
Sulcus
Long depression seen in teeth
Sulcus terminalis
The separation between the anterior two third and posterior third is marked by a V shaped depression, just anterior to foramen caecum. This is the Sulcus terminalis
Synarthrosis
 Sutures between two bones united through a fibrous membrane that is continous with the perisoteum
Synchondrosis
 A type of temporary cartilaginous joint. The intervening hyaline cartilage is replaced by bone by adult life.
Syndecan
Syndecans are integral membrane proteoglycans. Syndecans are not only matrix receptors but also co-receptors for growth factors and cytokines, capable of potentiating signal transduction events.
Syndesmosis
Fibrous joint in which opposing surfaces are united by fibrous connective tissues.
Synovial fluid
The fluid in the joint space
Taste buds
Small, ovoid or barrel shaped intraepithelial organs associated with valate, foliate, fungiform papillae in tongue and certain other parts of oral cavity and oropharynx. They are associated with perception of taste through a highly specialized central and local mechanism.
Tenascin
Tenascin, a large extracellular matrix molecule, also known as cytotactin and hexabrachion, is made up of six polypeptide chains assembled to form a sixarm structure capable of interacting with a variety f cells and extracellular matrix molecules. They bind to cell surface proteoglycan - Syndecan
Teratology
 It is the study of developmental defects caused by adverse factors in the environment
Tertiary dentin
 It is a dentin that is produced in reaction to noxious stimuli after the root formation is completed.
Tight junctions
 A junction where adjacent cell membranes appear to be cemented or fused together. Sometimes fused areas are broken by non-fused regions. These junctions form a tight seal around the apical portion of cells, forming a water-tight barrier. These junctions are also involved in maintaining membrane, allowing specializations, compartmentalization of the apical and basal membranes.
Tome’s layer
The sudden bending of the dentinal tubules, coalescing and looping of dentinal tubules nearer the cement-enamel junction in the apical third of roots. 
Tome’s process
 It is the projection of the ameloblasts in to the newly secreted enamel matrix during amelogenesis.
Tomes granular layer
 A granular appearing layer in the root dentin caused by the coalescing and looping of the terminal portions of the dentinal tubules
Tonofibrils
Small filaments of keratin bundled together, together with desmosomes forms the intercellular bridges in light microscopy.
Tonofilaments
Keartin filaments bundled together
Trabecular bone
Irregular Network like appearance.
Transduction
The type of sensory conduction perceived by odontoblastic process through subtle changes in dentinal lymph
Transeptal fiber system
The fibers of periodontium that runs across the alveolar septum especially in posterior multi-rooted teeth
Transit time
The time between the formation and secretion of collagen molecule
Transparent dentin
See sclerotic dentin
Transverse Ridge
Union of 2 triangular ridges that cross the posterior surface of a tooth
Triangular Ridges
Main ridges on each cusp that run from the tip of the cusp to the central part of the occlusal surface
True denticles
This is a structure formed as a result of regressive change of pulp where there is a calcification in the pulp with the structure resembling dentin.
Tubercle
 Small elevation of enamel on the crown
Tublin
A protein that is found in odontobalstic process and is an intracellular protein of microtubules
Tuftelin
A non amelogenin protein of enamel and a nucleator for enamel crystaliization. The enamel layer adjacent to dentinoenamel junction is heavily mineralized as soon as it is formed is due to the presence of:
Vermillion zone
The junction of oral mucosa and skin in lips is the vermillion.
Vestibular lamina
 Is an epithelial thickening arising labial and buccal to the dental lamina that hallows out and forms the vestibule.
Vimentin
The intermediate filament type found in connective tissue cells
Vinculin
A peripheral cytoplasmic protein that interacts with integrin through Talin. Conformational changes in Vinculin cause it bind to actin iand completing the cell’s contractile elements with fibronectin in  Extracellular matrix
Volkman canals
The connection between adjacent Havesian’s canal in osteon containing blood vessels.
Von Kroff’s fibers
The larger diameter collagen fibers with an extreme affinity for silver stain, composed mainly of type III collagen and found in the mantle dentin, adjoining the Dentinoenamel junction
Weil’s zone
See cell free zone
Woven bone
First formed bone with irregularly oriented collagen fibers of varying diameters.
Zona occludentes
See tight junctions
Zonula adherens
See adherence junctions