Cem.per.

Cementum is a hard, avascular, connectivetissue, that covers the root of the teeth.

Root cementum is a hard non-vascularized, and

non-innervated tissue covering the tooth root.

It does not have ongoing remodeling like bone but

continues to grow with age.

It originates from the third element of the dental

germ - the dental follicle after stimulation by

Hertwig's epithelial root sheath.

Cementum formation involves two tissues - the

mesenchyme of the tooth follicle and the ectoderm

of the Hertwig`s root sheath.

DEVELOPMENT OF

CEMENTUM

CEMENTUM FORMATION IS CALLED

CEMENTOGENESIS.

CEMENTOBLASTS ARE THE CELLS RESPONSIBLE FOR

CEMENTOGENESIS.

Cementogenesis

It’s occur right after the enamel was completely formed;

The outer and inner enamel epithelia together form the epithelial root sheath of Hertwig which is responsible for determining the shape of the root;

The growth of sheath does not occur downward into jaws but that proliferation in cells of sheath causes an upward movement of developing tooth.

These two epithelial layers, which are separated by stratum

intermedium and stellate reticulum, are connecting in the area of

the future enamel-cementum junction and form the cervical loop.

Stratum intermedium and stellate reticulum are pushed and a

double layer of outer and inner enamel epithelium is obtained.

The following step is a proliferation in-depth to the dental follicle. The

name of this proliferation is Hertwig`s epithelial root sheath.

Its function is to stimulate mesenchymal cells of the dental follicle to

differentiate.

Three layers of cells of the dental follicle are formed. The innermost

differentiates to cementoblasts that will build the cementum, the

outermost differentiate to osteoblasts that build the alveolar bone,

and the middle differentiates to the fibroblasts that build the

periodontal ligaments.

Cervical loop These two epithelial layers which are

separated by stratum intermedium and

stellate reticulum become continous in

the area of the future enamel-

cementum junction;

Hertwig’s epithelial root

sheath

The Hertwig's epithelial root sheath

(HERS) is a proliferation of epithelial

cells located at the cervical loop

of the enamel organ in a

developing tooth.

Hertwig's epithelial root sheath

initiates the formation of dentin in

the root of a tooth by causing the

differentiation of odontoblasts

from the dental papilla.

The root sheath eventually

disintegrates, but residual pieces

that do not completely disappear

are seen as epithelial cell rests of

Malassez (ERM).

Epithelial root sheath(diaphragm);

Both epithelial layers merged apically into one;

At the bottom form 4-5 cells -guides that are not divided;

Cervically begins disintegration of epithelial sheat and beginspenetration into mesenchymalcells.

The first stimulation of the Hertwig's epithelial root

sheath initiates the formation of root dentin by

differentiation of odontoblasts from the dental papilla.

Both epithelial layers merged apically into one.

At its end are forming 4-5 cells, without proliferation.

They do not divide, only direct the proliferation of the

Hertwig`s epithelial root sheath in order to control the

length, thickness, curves, and number of roots.

Cervically begins disintegration of epithelial sheet and begins penetration into mesenchymal cells.

The root sheath eventually disintegrates, but residual pieces that

do not completely disappear are seen as epithelial cell rests of

Malassez (ERM).

Hertwig`s epithelial root sheath stimulated the differentiation of

cementoblasts.

At the same time, they deposit a thin acellular cementum over the

root dentin, called intermediate cementum.

It plugs up the dentinal tubules and isolates and protects the

dentin.

This first layer of cement serves as the basis for building the cement.

Immediately afterward, the disintegration of

the Hertwig's epithelial root sheath begins.

The epithelial cells are grouped into clusters of

3-4 cells, which are quickly removed from the

root surface.

It separates the organic matrix secreted by

the cement regions.

Cementoblasts are cuboidal cells. They are

arranged on the outer surface of a hyaline layer

that covers the dentine.

Cementoblasts start to secrete an organic matrix of

cementum. It consists of proteoglycan and intrinsic

collagen fibers.

After that, cementoblasts are involved in

mineralization of the organic matrix.

Cementogenesis occurs when Hertwig`s root

sheath disintegrates.

This disintegration of the sheath allows the

undifferentiated cells of the dental sac to come into

contact with the newly formed surface of root dentin.

This contact induces differentiation of the cells to

immature cementoblasts.

They turn into oblong cells arranged along the

developing root and are preparing for protein

synthesis and secretion.

The cementoblasts are producing fibers, are

synthesizing of an amorphous organic matrix, and

mineralize it.

The organic matrix of cementum is produced by

fibroblasts in the middle layer of the Hertwig's

epithelial root sheath.

It starts the production of thick collagen fibers

incorporated into the cementum organic matrix,

which are perpendicular to the root surface.

They remain part of the cementum.

They are called Sharpe's collagen fibers.

They are coming out of the cementum lick a part

of periodontal ligaments.

Cells including in cementogenesis

There are two types of differentiated cells included

in cementogenesis:

Cementoblasts are situated directly over the dentin;

Subcementoblasts (fibroblasts) are located just below cementoblasts. They are producing Sharpe's

collagen fibers.

Stages of cementogenesis

Cementogenesis has two stages;

In the first, an organic matrix is formed,

and in the second, it is mineralized.

Organic matrix formation has

two phases:

In the first, the fibrillar scaffold is formed,

and in the second, amorphous organic and

inorganic matter is deposited on it.

The organic matrix is made up

of two groups of fibers.

The first group is produced by subcementoblasts and is named Sharpey's fibers.

They are perpendicular to the root.

The second group is formed by cementoblasts. It is composed of thin fibers.

They are perpendicular to the Sharpey's fibers and are parallel to the longitudinal axis of the root.

When the fibril matrix is ready, the cementoblasts synthesize and deposit an amorphous organic matter over them.

A noncollagenous matrix is deposited on the collagen network, which masks the fibers.

Amorphous organic matter is consist of bone sialoprotein and osteocalcin. Amorphous inrganic matter is deposited in parallel with organic matter. It consists of calcium and phosphate ions.

The next step is the mineralization of the matrix.

When the thin layer of cementum matrix has formed, mineral ions

come from tissue fluid. Calcium and phosphate ions will be deposited

as hydroxyapatite crystal along axes of collagen fibers.

As cementum continues to increase in thickness, more follicular

(extrinsic) fibers become included in cementum, known as Sharpey’s

fibers.

After the formation of the first layer, cementoblasts move away and

free up a new space for matrix deposition and its mineralization. The process is repeated until the root is forming. While the root is

developing, the process occurs in an apical direction.

The first formed cementum does not contain cells. Cementoblasts will

be included in the next layers of the cementum. The enclosed

cementoblasts are known as cementocytes and found in lacunae.

Cementogenesis

The differentiation of

odontoblasts from

ectomesenchymal cells;

The fragmentation of

Hertwig`s epithelial root

sheath;

The ensuing differentiation of

cementoblasts from Hertwig`s

sheath cells or follicle cells.

Cementum is made

by cementoblasts

Derived from

undifferentiated

mesenchyme through

intermediate

precemntoblast stage in

cuboidal cell’s form;

They are arranged on outer

surface of hyaline layer that

covers the dentine.

Cementoblasts are responsible for

deposition of organic matrix of

cementum which consist

proteoglycan and intrinsic

collagen fibers.

Also they are responsible for

subsequent mineralization of

organic matrix (cementoid or

precementum).

A. HERS did not show any signs of

fenestration at this stage;

Single cells (arrowheads) were

positioned between ameloblasts

(amel) and the beginning of HERS.

(B). Tooth mineralization was significantly advanced .

The bilayered unit of HERS was still distinguishable at the apex

(hers) but had lost its continuity with

the ameloblast layer (amel). Instead,

bundles of mesenchymal cells (mes,

between arrowheads) as well as

fibrous structures (fib) were occupying

the developing root surface.

Isolated epithelial cells (ep) were localized between mesenchymal

tissues and HERS.

Note the clear separation between ameloblast cell layer (amel,

upper row of arrowheads) and mesenchymal cells (mes) covering

the developing root surface.

The fragmentation of Hertwig`s epithelial

root sheat:

With residual portion formingthe epithelial rests of Malassez

The ensuing differentiation of cementoblasts;

The follicle contribution to theformation of the fiber bundlesof the periodontal ligament.

A1 and A2. Note how tubular cells from adjacent to the ameloblast cell layer (arrowheads) were interrupting the

continuity of the ameloblast cell layer (amel).

B1 and B2. The enamel layer (en) and the ameloblast cell layer

(amel) clearly demarked the cervical margin of the developing

tooth

crown. A membrane (arrowheads) separated the ameloblast

cell layer (amel) from the mesenchymal cells (mes) occupying

the developing root surface. There

were only a few epithelial cells (ep) in immediate proximity to the root dentin surface (de)..

Cementogenesis

Cementogenesis occurs when

Hertwig`s root sheath

disintegrates;

This disintegration of the sheath

allows the undifferentiated cells

of the dental sac to come into

contact with the newly formed

surface of root dentin;

This contact of the dental sac

cells with the dentin surface

induces these cells to become

immature cementoblasts.

Periodontal ligament and

alveolar bone development

As the crown and root

develop, the surrounding

supporting tissues of the

tooth are also

developing. The

mesenchyme from the

dental sac begins to

form the periodontal

ligament (PDL) adjacent to the newly formed

cementum.

The mesenchyme of the dental sac

also begins to mineralize to form the

tooth sockets or alveoli of the alveolar

bone surrounding PDL.

This process involves forming collagen

fibers that are immediately organized

into the fiber bundles of the PDL. The

ends of these fibers insert into the outer

portion of the cementum and the

surrounding alveolar bone to support

the tooth.

Hertwig`s epithelial root sheat

Thedifferentiation of thecementoblasts;;

The begining of thedesintegration of Hertwig`s sheat.

The begining of

cementogenesis

Dodge the cementoblastsfrom the dentin;

Secretion of matrix of cementum;

Disintegration of cervical cells of the sheat.

Differentiation of dental

follicle cells

The cementoblasts –directly over the dentin

They are involved in the secretion of the

organic matrix of cement and its mineralization;

Subcementoblasts(fibroblasts)-just below

them

They produce fibers that enter into the

matrix.

There are two types of differentiated cells:

Desintegration of the Hertwig`s root sheat endformation of cementum end periodontal ligaments

(1)Hertwig`s sheat;

(2)Epithelial rests of

Malassez;

(3)The cells of the dental

follicle;

(4) Cementoblasts;

(5)Priodontal ligaments;

(6) Osteoblasts;

(7) Alveolar bone;

(8) Odontoblasts.

Cementogenesis

СВ - cementoblasts;

D - Dentin;

ECR -Epithelial rests of Malassez;

DF - Dental folicle.

Mineralization occurs :

When the thin layer of cementoid has formed, mineral salt comes from tissue fluid;

Calcium and phosphate ions will deposited as hydroxyapatite crystal along axes of collagen fibers.

As cementum continues to increase in thinkness, more follicular (extrinsic) fibers become included in cementum, known as Sharpey’s fibers right after periodontal ligament become established.

During the root is developing, those

process occurred on apical direction

:

Proliferation of cells of epithelial root sheath of Hertwigs;

Dentine formation;

Fragmentation of older part of sheath;

Differentiation of new cementoblasts;

Formation of cementum.

Cementum

A. Haversian bone ;

B. Bundle bone (A & B make up alveolar bone proper);

C. Reversal line;

D. Osteoid ;

E. Endosteum, composed of osteoblasts ;

F. Cementoid (the organic matrix of cementum) ;

G. Pericementum, composed of cementoblasts.

(A) the position of pulp (pulp), dental follicle (df), mineralized dentin (md), periodontal ligament

(lig), Hertwig’s epithelial root sheath (hers)

epithelial diaphragm (epd), predentin (pd),

dentin (dent), and several blood vessels (bv),

(B) Note the position of epithelial and

mesenchymal tissues on the predentin surface at

the apical tip of the root. At the apical margin of

the root dentin the periodontal ligament (lig) was

in direct contact with the non-mineralized

predentin (pd).

Hertwig’s root sheath (hers) was separated from

the root surface by a periodontal ligament cell

layer measuring at least 10 cell layers in thickness.

The nude predentin surface (pd) was not

covered by mineralized dentin or cementum.

At this stage, mesenchymal

cells of the ligament (lig) had

direct access to the root

surface. Due to their spatial

separation, HERS cells had lost

their opportunity to deposit

cementum on the root dentin

prior to their departure from the

root surface

Before tooth erupts :- Extrinsic fiber are incorporated in cementum and lie parallel

to the root structure.

After tooth erupts :

The fiber become oblique.

It is known as the precursor

of periondontal ligament

fibers.

Extrinsic fiber

Cementum which is formed first:

Does not contain any closed cells, but

cementoblast are included in later cementum;

These enclosed cementoblast are known as

cementocytes and found in lacunae;

Multi-rooted teeth – the formation of root

diaphragm

Multi-rooted

teeth:

Like anterior teeth, multi-rooted

premolars and molars originate as a

single root on the base of the crown;

This portion on these posterior teeth is

called the root trunk;

The root of a posterior tooth divides

from the root trunk into the correct

number of root branches for its type;

During the formation of the enamel

organ on a multi rooted tooth, elongation of its cervical loop occurs

in such a way that long, tongue like

horizontal epithelial extensions or

flaps develop within.

In teeth with more than one root

The initial single primary apical

foramen, formed by the epithelial

diaphragm of root sheath

Hertwig’s, become divided into two

or more secondary apical foramina

by tongues of epithelial tissue from

diaphragm.

These fuse in future

furcation area of the roots.

The number of secondary

apical foramina is

determined by the

presence of groups of

blood vessels which enter

the dental papilla.

Two types of cementum form:

Cellular and Acellular

Acellular cementum forms first. The

cementoblasts differentiate from follicular

cells, which can only reach the surface of

the tooth's root once Hertwig's Epithelial

Root Sheath (HERS) has begun to

desentigrate;

The cementoblasts secrete fine collagen

fibrils along the root surface at right angles

before migrating away from the tooth;

As the cementoblasts move, more collagen is deposited to lengthen

and thicken the bundles of fibers;

Noncollagenous proteins, such as bone sialoprotein and

osteocalcin, are also secreted;

Acellular cementum contains a secreted matrix of proteins and

fibers;

As mineralization takes place, the cementoblasts move away from

the cementum, and the fibers left along the surface eventually join

the forming periodontal ligaments

Cellular cementum

Develops after most of the tooth formation is complete

and after the tooth occludes (in contact) with a tooth in

the opposite arch. This type of cementum forms around

the fiber bundles of the periodontal ligaments;

The cementoblasts forming cellular cementum become

trapped in the cementum they produce;

The origin of the formative cementoblasts is believed to

be different for cellular cementum and acellularcementum;

One of the major current hypotheses is that cells

producing cellular cementum migrate from the

adjacent area of bone, while cells producing

acellular cementum arise from the dental follicle;

Nonetheless, it is known that cellular cementum is

usually not found in teeth with one root;

In premolars and molars, cellular cementum is

found only in the part of the root closest to the apex

and in interradicular areas between multiple roots.

The fate of Hertwig`s

epithelial toot root sheath

With the progressive formation of cementum and shaping the root, the Hertwig`s sheat undergoes complete disintegration;

Cementogenesis is completed with the construction of the root apex closure;

During toot root maturation, cellswithin fragmented root sheath formdiscrete masses surrounded by a basement membrane, known asepithelial cell rests of Malassez.

Cementum Varieties

Cemento enamel junction

In 30% the cementum andenamel meet as a buttjoint, forming a distinctcementoenamel junctionat the cervical margin –edge to edge;

In 60% the cementumoverlaps the enamel;

In 10% have a gap between the cementum and enamel – it lead to sensitivity at this site.

Cementum may be classified in

the following ways:

By location:

Radicular cementum: The

cementum that is found on the root

surface.

Coronal cementum: The cementum

that forms on the enamel covering

the crown.

By cellularity:

Cellular cementum:

Cementum containing

cementocytes in lacunae

within the cementum matrix.

Acellular cementum:

Cementum without any cells

in its matrix.

By the presence of collagen fibrils in the matrix:

Fibrillarcementum: Cementum with a matrix that contains well-defined fibrils of type I collagen.

Afibrillarcementum: Cementum that has a matrix devoid of detectable type I collagen fibrils. Instead, the matrix tends to have a fine, granular consistency.

Extrinsic fiber cementum: Cementum that contains

primarily extrinsic fibers, i.e. Sharpey's fibers that are

continuous with the principal fibers of the periodontal

ligament.

Since the fibers were originally produced by periodontal ligament fibroblasts, they are considered "extrinsic" to the

cementum.

These fibers are orientated more or less perpendicularly to

the cementum surface and play a major role in tooth anchorage.

By the origin of the matrix fibers (applies only to fibrillar

forms of collagen

Intrinsic fiber cementum: Cementum that contains

primarily intrinsic fibers, i.e. fibers produced by

cementoblasts and that are orientated more or less

parallel to the cementum surface. This form of

cementum is located predominantly at sites

undergoing repair, following surface resorption. It

plays no role in tooth anchorage.

Mixed fiber cementum: Cementum that contains

a mixture of extrinsic and intrinsic fiber cementum.

The description of

the classes of

cementum

Cementum Varieties

AEFC – acellular extrinsic fiber cementum;

CIFC –cellular intrinsic fiber cementum;

MC – mixed (alternating layers of acellularand cellular) cementum;

IC – Intermediate cementum.

AAC - Acellular afibrillar (prymary)

cementum

1. Acellular, afibrillar cementum

This cementum is mostly composed of mineralized matrix,

without detectable collagen fibrils or cementocytes. It is

produced exclusively by cementoblasts. It is typically found

as coronal cementum on human teeth over enamel and dentin in proximity to the cementoenamel junction

Cervical portion of cementum

A –deposition of cementum on the enamel in the cervical area;

Internal basal lamina and hemidesmosomesattached to the reduced enamel epithelium;

2. Acellular, extrinsic fiber cementum

This type of cementum has a matrix of well-defined, type I collagen

fibrils;

The fibrils are part of the, densely packed Sharpey's fibers, that are

continuous with the principal fibers of the periodontal ligament;

Because of their dense packing, the individual Sharpey's fibers that

form the bulk of the matrix may no longer be identifiable as individual

fibers within the cementum layer;

This cementum, which is acellular, is located in the cervical two-

thirds of the root of human teeth;

It plays a major role in tooth anchorage.

Acellular Extrinsic Fiber Cementum

A: Tightly packed Sharpey´sfibers.

B: Sharpey´s fibers are with central pitting;

Acellular Extrinsic Fiber Cementum

(Primary cementum)

It is mainly found on cervical and middle root portions, covering 40% to 70% of the root surface;

It serves the exclusive function of anchoring the root to periodontal ligament;

The acellular extrinsic fiber cementum matrix consists of a densefringe of short collagenous fibers that are implanted into the dentinal matrix (glycosaminoglycans) and are oriented about perpendicularly to the root surface;

When they become elongated and eventually continuous with theprincipal periodontal ligament fibers they are called Sharpey´s fibers.

Intermingling of collagen fiber bundles

with those at the unmineralized dentin.

The final connection between the

collagen fiber bundels of acellular

cementum and dentin surgace are

shown.They are perpendicular to the dentin and

penetrates between the cementoblasts.

Cross section of the cementum

Acellular cementum

Cellular cementum

Cementocytes

Lines indicate apposition, a period of rest in the deposition of the cement

3. Cellular, intrinsic

fiber cementum

This cementum contains cementocytes in a matrix composed almost exclusively of intrinsic fiber cementum;

It is located at sites of cementum repair.; It plays no part in tooth anchorage.; However, it may be covered over by

extrinsic or mixed fiber cementum, both of which are able to provide new anchorage;

Once the tooth is in occlusion, a more

rapidly formed and less mineralized

variety of cementum, cellular intrinsic

fiber cementum, is deposited;

Differentiating cementoblast extend cell

processes and deposit the collagen

fibrils;

As cementum deposition progresses, cementoblasts become entrapped in the extracellular matrix they secrete;

These entraped cells, with reduced secretory activity, are called cementocytes, and the space they occupy is the osteocytic lacuna.

Cementocytes

Cementocyteshave processes that lodge in canaliculi that communicate but do not form a syncytium that extends all the way to the surface’

As cementum deposition progresses, cementoblasts become

entrapped in the extracellular matrix they secrete.

These entrapped cells have reduced secretory activity.

They are called cementocytes, and the space they occupy is the

osteocytic lacuna.

Cementocyte's processes are in canaliculi. They communicate but do

not form a syncytium.

They are always directed to the surface of the cementum.

The nourishment of the cells is believed to occur essentially by

diffusion, and cementocytes in deeper layers may not be vital.

Collagen fibrils in the CIFC are deposited haphazardly during the rapid

phase. However, subsequently the bulk of fibrils organize as bundles

oriented parallel to the root surface.

Nourishment of the cells is believed to occur

essentially by diffusion, and cementocytes in

deeper layers may not be vital.

Collagen fibrils in the CIFC

They are deposited haphazardly during the rapid

phase;

Hawever, subsequently the bulk of fibrils organize as

bundles oriented parallel to the root surface.

Acellular and Cellular cementum

А –Acellularcementum

В –cellularcementum in:

•Periapical region.

4. Cellular, mixed fiber cementum

It is found on the apical third of the root and in furcations (i.e.

between roots);

In these locations, the rate of cementum formation is usually

more rapid than in the cervical region;

The mineralized, extrinsic collagen fibers (Sharpey's fibers) run a

more irregular course than in acellular, extrinsic fiber cementum;

Intrinsic fibers are found interspersed among the extrinsic fibers

of the cementum matrix, so that individual Sharpey’s fibers are

more readily identifiable than in extrinsic fiber cementum;

Cementoblasts are trapped in hollow chambers (or lacunae)

where they become cementocytes.

Cellular Mixed Fibrils Cementum

Cellular Mixed FibrilsCementum(CMFC) andperiodontal ligaments (PDL);

Sharpey´s fibers (SF);

Cementoblasts (CB);

Cementocytes (СС).

Cellular Mixed Fibrils Cementum

When the PDL becom organized, cellular cementum continues to be

deposited around the ligament fiber bundles, wich become

incorporated into the cementum and partially mineralized, thereby

creating cellular mixed fiber cementum;

It has:

Inclusion of cementocytes;

It has laminated structure;

The presence of cementoid on its surface;

Distinguishing between the fine-fibered, densely packed intrinsic fibers

running parallel to the root surface and incorporated extrinsic fibers

running at right angles to the root.

5. Intermediate Cementum

IC is a thin. noncellular, amorphous layer of hardtissue approximately 10µm thick;

It is deposited by the inner layer of the epithelial cellls of the root sheath;

Deposition occurs immediately before the epithelial root cells disintegrate as a sheet and migrate away from the root into the periodontal tissue;

It is the first layer of hard tissue deposited, and itseals the tubules of dentin;

IC is composed of enamel protein rather thancollagen

Longitudinal section of cementum

Sharpey`s fibers

Incremental lines

Periodontalligaments

Cross section of the toot roots –

incremental lines of cementum

Different layers in the cementum

Cimenticles

A cymenticle is a calcified ovoid

or round nudule found in the

periodontal ligaments;

Single or in a group they are

near the surface of the

cementum;

Their origin may be a nidus of

epithelial cells that are

composed of calcium

phosphate and collagen in the

same amounts as cementum.

Composition of the Cementum

Since cementum is not a uniform, mineralized

connective tissue, differences in the proportional

composition of the chemical constituents exist

between the cementum varieties.

Thus, the percentages of its chemical components

may vary from sample to sample, particularly in

different species.

Cementum has a similar composition to bone -

to about equal parts per volume, cementum is

composed of water, organic matrix and

mineral.

About 50% of the dry mass is inorganic, and

consists of hydroxyapatite crystals.

The remaining organic matrix contains largely

collagens, glycoproteins and proteoglycans.

Mineral composition

Cementum is generally less mineralized than root

dentin;

Acellular extrinsic fiber cementum appears more

highly mineralized than cellular intrinsic fiber

cementum and cellular mixed stratified cementum;

The mineral component is the same as in other

calcified tissues, that is, hydroxyapatite -

Ca10(PO4)6(OH)2, with small amounts of

amorphous calcium phosphates present;

As in other hard tissues, the hydroxyapatite of

cementum is not pure, but contains other

elements (ions) incorporated into mineral phase

during mineralization;

Thus, cementum contains 0.5-0.9%;

Have a high fluoride content compared to other

mineralized tissues (up to 0.9% as weight);

Cementum also contains 0.1-0.3% sulfur, in

particular Cu+2, Zn+2 and Na+.

Organic composition

The organic matrix of cementum is

composed primarily of collagens type I

and III collagen;

Cementum contains two major non-

collagenous proteins:

bone sialoprotein (BSP);

and osteopontin (OPN).

Both are phosphorilated and sulfated

glycoproteins.;

These proteins,which are prominently expressed

in acellular extrinsic fiber cementum and

acellular afibrillar cementum, bind tightly to the

collagenous matrices and hydroxyapatite, and

they possess cell attachment properties.

Comparison of the composition of the

enamel, dentin, cementum, and bone

% Enamel Dentin Cementum Bone

Mineral 95 70 61 45

Organic

composition 1 20 27 30

Water 4 10 12 25

Cement Repair

Cement repair is a protective function of

cementoblasts after resorption of rooth dentin

and cementum;

These cells are programmed to maintain a

smooth surface of the root;

Loss of cementum is accompanied by loss of

attachment fibers;

When this occurs, repair cementum may be

deposited by cementoblasts in the defect.

The functions of the cementum

Roofing function;

Function to attach the periodontal ligaments;

Protective function:

Adaptive function.