What is ……?

Answers

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