Cementum is the mineralized tissue covering tooth roots. It consists of inorganic minerals like hydroxyapatite and organic materials like collagen. Cementum forms through cementogenesis, led by cementoblasts. There are two stages of cementogenesis - matrix formation where cementoblasts lay down an unmineralized matrix, and mineralization where crystals are deposited. Cementum can be classified as acellular or cellular based on the presence of cementocytes, and primary or secondary based on formation time. Cementum functions to attach teeth to bone and allows for adaptation.

1. Presentation By - Ayushman Ghosh, B.D.S. 1st Year, TODCH
Instructed By – Dr. Seema M.,
Asst. Prof., Dept. of Oral Path., TODCH

2. 1. What is Cementum? What is it consisted or made up of?
2. How is Cementum formed?
3. What are the types of Cementum? Why are they classified like that?
4. How are Cementum and Enamel connected to each other?
5. What is the function of Cementum?
6. How can we apply what we studied about Cementum in our clinics?

3. Cementum is the
mineralized dental tissue
covering the anatomic
roots of human teeth.
It was first demonstrated
microscopically in 1835 by
two pupils of Purkinje,
Fränkel and Raschkow.
Location/Extension/Situation:
It begins at the cervical portion of tooth at CEJ and continues to the
apex
Anatomically: Part of Tooth
Functionally: Part of Peridontium

4. • Hardness & Calcification < Dentin
• Light yellow in colour, with dull surface,
lacks luster, and is lighter than Dentin
• Permeability of cementum is more than
that of Dentin. However, the permeability
decreases through age.
Thickness
• Thinnest at CEJ – 20-50µm
• Thickest at apex – 150-200µm
Cementum is thicker in the distal surface than the mesial surface probably
because of the functional stimulation of the mesial drift.
Average Thickness – 95µm at 20, 128µm at 60

5. On the basis of Dry weight,
Cementum from fully formed permanent teeth contains:
Inorganic substances – about 45% to 50%
Organic material and water - 50% to 55%
Inorganic portion consists
• Mainly of calcium and phosphate in the form of hydroxyapatite.
• Numerous trace elements are found in cementum in varying amounts.
• It is of interest that cementum has the highest fluoride content of all the mineralized
tissues.
Organic portion consists
• Primarily of type I collagen and protein polysaccharides (proteoglycans). The other types of
collagen seen are types III, V, VI and XII.
• Noncollagenous proteins play important roles in matrix deposition, initiation and control of
mineralization and matrix remodeling.
These include: Bone sialoprotein (BSP), osteopontin, Cementum derived attachment protein (CAP)
• Proteoglycans: Chondroitin sulfate, heparan sulfate, hyaluronate, keratan sulfates–fibromodulin
and lumican, versican, biglycan and osteoadherin
• Growth Factors: TGFβ, various Bone Morphogenetic Proteins (BMPs), FGF, IGF, EGF and platelet
derived growth factor (PDGF)
• Cementum derived growth factor(CDGF) is seen exclusively in cementum. These are insulin like
molecules and help in resorption of cementum and enhance proliferation of gingival fibroblasts and
peridontontal ligament cells

7. Cementogenesis is the process of cementum formation which covers
the tooth root by cementoblasts of mesenchymal origin.
DEFINITION:
Stages of Cementogenesis:
Cementogenesis is subdivided into two stages:
A) Prefunctional Stage: It can be divided into two stages:
(i) Matrix Formation
(ii) Mineralization
B) Functional Stage
What are the cells involved in Cementogenesis?
There are mainly three types of cells involved in cementogenesis:
(i) Cementoblasts
(ii) Cementocytes
(iii) Fibroblasts

8. CEMENTOBLASTS:
1. Cementoblasts are large cuboidal cells that forms from
the follicular cells around the root of a tooth
2. These are found on the surface of both cellular and accellular
cementum
3. Cementoblasts synthesize collagen and protein polysaccharides, which
make up the organic matrix of cementum
4. These cells have numerous mitochondria, a well-formed Golgi apparatus, and
large amounts of granular endoplasmic reticulum
5. At the superficial surface, the collagen fibrils produced by the cementoblast
form a fibrous fringe perpendicular to periodontal space. These cells retreat and
intermingle with the fibroblasts of the periodontal ligament. The processes which
extend from cementoblasts to deposit cementum are known as cementoblastic
processes.

9. Phenotype of Cementoblasts
 Cementoblasts are identified by 3H thymidine labeling.
 Apart from the inner cells of the dental follicle, cementoblasts are also
reported to differentiate from HERS.
 The cementoblasts that are derived from the dental follicle have a
similar morphology and phenotype to osteoblasts and are shown to be
involved in the formation of CIFC.
 The cementoblasts, which are reported to be derived from HERS, have
a similar morphology to fibroblasts and a different phenotype than
osteoblasts and are shown to be involved in the formation of AIFC.
 These two types of cementoblast precursors differ in the expression
of surface receptors and their reaction to signaling molecules or
differentiating factors

10. Formation of Cementoblasts

11. Histology of Cementoblasts

12. CEMENTOCYTES:
 Cementocytes are spider-like cells that are incorporated into cellular cementum.
 The cell body is located in spaces called lacunae and their processes are present in
canaliculi.
 A typical cementocyte has numerous cell processes or canaliculi, radiating from its cell
body. These processses may branch and anastomose with those of neighbouring cells. Most
of the processes are directed towards the periodontal surface of cementum.
 Cytoplasm of cementocytes in deeper layer of cementum contains few organelles.
Endoplasmic reticulum appears dilated and mitochondria are sparse. These characteristics
indicate that cementocytes are either degenerating or marginally active cells.
 In deeper layer cementocytes show signs of degeneration such as cytoplasmic clumping
and vesiculation.
 In more deeper layer of cementum lacunae appear empty and suggesting complete
degeneration of cementocytes

13. Histology of Cementocytes

15. Stages of Cementogenesis
Cementogenesis is subdivided into two stages:
A)Prefunctional Stage: It can be divided
into two stages:
(i) Matrix Formation
(ii) Mineralization
B) Functional Stage

17. A) Matrix formation
Once the root dentin(radicular dentin)
formation has been initiated the
Hertwig’s root sheath fragments into a
network which allows the
ectomesenchymal cells of dental follicle
to pass through and contact the root
dentin.
The direct contact of the follicular
cells of dental follicle with the newly
formed dentin results in the
differentiation of undifferentiated
mesenchymal cells to cementoblasts.

18. A) Matrix formation
These newly formed cementoblasts
extend numerous tiny cytoplasmic
processes into the loosely arranged
unmineralized dentinal matrix
Cementoblasts lay down cementum
matrix(cementoid) leading to an
intimate integration of the two
different fibril populations forming
dentinocemental junction. Though its
not distinctive as the fibres of dentin
and cementum intermingle at the
interface

19. A) Matrix formation
During matrix formation, fibroblasts form collagen fibers(Sharpey’s fibers),
which become embedded in the matrix to provide attachment of the root to
the surrounding bone.
 Discrete bundles of collagen fibers which are seen in tangential section, these
bundles are known as Sharpey’s Fibers.
 Sharpey’s fibers make up the substantial portion of cementum
 When cementum remains relatively thin these sharpey’s fibers crosses the entire
thickness of cementum.
 With further apposition of cementum the larger part of fiber is incorporated in
cementum
 Cemental surfaces with actively mineralizing fronts have numerous small openings
that correspond to site where individual Sharpey’s fibers enter the tooth
 The openings represent unmineralized core of fibers

21.  The first layer of cementum that is formed by inner cells of the Hertwig’s
epithelial root sheath and is deposited on the the root’s surface is known as
hyaline layer of Hopewell-Smith.
 It is the most peripheral layer of initially unmineralized dentin that forms
immediately subjacent to the cementodentinal junction (CDJ).
 It eventually mineralizes, but not before the rest of the dentin is already
mineralized.
 It is 0.5-0.8 µm thick and contains enamel matrix-like protein as well as the
proteins one would expect to find in dentin.
 It is into this hyaline layer that the initial fibers of the periodontal
ligament embed themselves.
 It aids the cementum to bind with dentin.
 The role of this layer is to seal the CDJ before HERS degenerates.

22. A. Accellular Cementum
B. Hyaline layer of Hopewell Smith
C. Granular layer of Tomes
D. Dentin

23. B) Mineralization
 It begins in the depth of the cementum matrix (cementoid tissue), where, fine
hydroxyapetite crystals are deposited between and within the collagen fibrils
 Mineralization of the outermost layer of dentin matrix (mantle dentin), appears
to be delayed until the implantation of the cementum matrix is established and
the dentinal matrix is completely covered with the collagen fibrils of cementum

24. 1. These are incremental lines of cementum which represent the rest periods in
cementum formation and are more mineralized than the adjacent cementum.
2. Both cellular and acellular are arranged in lamillae separated by incremental
lines
3. These lines are parallel to the long axis of the root.
4. Theses can be best seen/observed in decalcified sections under light
microscopy
ACELLULAR CEMENTUM CELLULAR CEMENTUM

25.  This stage of cementogenesis commences/begins when
the tooth is about to reach occlusal level and continues
throughout life
 It is associated with the attachment of root to the
surrounding bone and continues throughout life.
 It is mainly during this stage that adaptive and
reparative processes are carried out by the biological
responsiveness of cementum
 Cementum deposition apically (near the apex) compensate
attrition

26. Molecular Factors regulating Cementogenesis

29. Following are the types of Cementum:
 Based on CELLULARITY:
 Acellular Cementum: Cementum present without the cells (cementocytes)
 Cellular Cementum: Cementum consisting of cells (cementocytes).
 Based on TIME OF ORIGIN:
 Primary Cementum: First formed cementum. It is acellular.
It consists of Peridontal ligament.
 Secondary Cementum: It forms after tooth reaches occlusal plane.
 Based on PRESENCE OF COLLAGEN FIBERS:
 Afibrillar Cementum: Cementum does not consist of fibers.
 Fibrillar Cementum: Cementum consisting of fibers.
 Based on ORIGIN OF CEMENTUM MATRIX FIBERS:
 Extrinsic Cementum: Cementum consisting of matrix fibers derived from
peridontal ligament.
 Intrinsic Cementum: Cementum consisting of matrix fibers derived from
cementoblasts.
 Mixed fiber Cementum: Cementum containing both extrinsic and intrinsic
fibers.

30. Acellar Cementum Cellular Cementum
1. Located from cervical to apical third 1. Located from apical third and furcations
2. It is formed earlier and is known as primary
cementum
2. Formed later and during repair and is known as
secondery cementum
3. It consists of noncollagenousprotein-tenascin,
fibronectin and osteocalcin are absent.
3. Noncollagenous proteins are present
4. Growth factors TGF β and IGF are not seen. 4. Growth factors are seen
5. Proteoglycans, i.e., versican, decorin, biglycan, and
lumican were not identified in the matrix
5. These proteoglycans are seen in the matrix
6. Cementoid is usually absent 6. Cementoid is seen on the surface
7. It contains only extrinsic fibers of the
periodontal ligament formed by fibroblast
7. Contains only intrinsic fibers produced by
cementoblasts
8. Probably the only type of cementum in single
rooted teeth
8. May be absent in single rooted teeth
9. Its main function is anchorage 9. Main function is adaptation and repair
10. It is formed slowly 10. It is formed rapidly
11. Incremental lines are closer to each other 11. Incremental lines therefore further apart
12. Cementocytes are not seen 12. Cementocytes, viable to varying degrees and
depths seen
13. Cementoblasts are suggestive to be derived from
HERS
13. Cementoblasts are suggested to be derived from
inner cells of dental follicle
14. Cementocytes do not express parathormone
receptors
14. Cementocytes express parathormone receptors
Differences between Acellular and Cellular Cementum

31. SCHROEDER & PAGE CLASSIFICATION
In 1986, scientists Schroeder and Page classified Cementum on into the
following types considering the location, morphology and histology of the
cementum:
1. Acellular Afibrillar Cementum
(AAC)
2. Acellular Extrinsic Fiber
Cementum (AEFC)
3. Cellular Intrinsic Fiber Cementum
(CIFC)
4. Cellular Mixed Stratified
Cementum (CMSC)
5. Acellular Intrinsic Fiber
Cementum (AIFC)

32. ACELLULAR AFIBRILLAR CEMENTUM(AAC)
1. It consists of mineralized matrix
2. AAC contains neither cells nor extrinsic or
intrinsic collagen fibers
3. This cementum does not have any function in
tooth attachment.
4. Less homogenous
5. According to Schroeder(1986)- Cementum
tissue cells are responsible for AAC formation
when they come in contact with enamel surface.
6. It is a product of cementoblasts
7. It is found in coronal cementum

33. ACELLULAR EXTRINSIC FIBER CEMENTUM(AEFC)
1. It is composed of densely packed bundles of
Sharpey’s Fibers (extrinsic fibers) & lack cells
2. AEFC is found in cervical 3rd of root – may
extend apically .
3. Thickness between 30-230µm
4. AEFC is the only type of cementum seen in
single rooted teeth.
5. It is a product of fibroblasts.
6. Cementoid is not found.
7. Main function is anchorage especially in single
rooted teeth

34. ACELLULAR INTRINSIC FIBER CEMENTUM(AIFC)
1. AIFC is generally seen in close
apposition to CIFC.
2. It (along with CIFC) helps in
adaptive function of
cementum, in maintenance of
tooth position in the apical
area of the tooth.
3. AIFC is formed when CIFC
formation slows down in areas
away from the advancing root
edge.
AIFC

35. ACELLULAR MIXED FIBER CEMENTUM(AMFC)
AMFC is formed in some areas which integrates both
extrinsic and intrinsic fibers in cementum. At present
not much is known about its specific location or
function.

36. CELLULAR INTRINSIC FIBER CEMENTUM(CIFC)
1. This cementum contains cells
but has no extrinsic fibers. The
fibers present are intrinsic
fibers which are secreted by
the cementoblasts.
2. CIFC fills resorption lacunae.
3. Majority of fibers organized
parallel to the root surface.
4. Cells have phenotype of bone
forming cells.
5. Very minor role in attachment
(virtually absent in incisors and
canine teeth).
6. Corresponds to cellular
cementum and is seen in middle
to apical third and
interradicular cementum.

37. CELLULAR MIXED FIBER CEMENTUM(CMFC)
1. The CMFC is a variant formed at a
faster rate with less mineralized
fibers.
2. The fibers of CMFC are derived from
the PDL fibroblasts and cementoblasts.
3. The intrinsic and extrinsic fibers form
an intricate pattern running between
each other at almost right angles and
different orientations, though the
number of intrinsic fibers is
comparatively less than the extrinsic
fibers.
4. The fiber bundles originating from
fibroblasts are ovoid or round with 5-
7mm diameter and the fibers
originating from the cementoblasts are
much more delicate and smaller aroound
1-2mm in diameter.

38. CELLULAR MIXED STRATIFIED CEMENTUM(CMSFC)
1. In this type CIFC alternates with AEFC.
2. It contains cells and composed of both intrinsic
and extrinsic(Sharpey’s) fibers.
3. It is a co-product of cementoblasts and
fibroblasts.
4. It appears primarily on apical third of the root,
in the apices furcation areas.
5. The thickness varies from 100 to 1000mm.
6. With light microscope this tissue is easily
identified because:
a) It includes cementocytes within lacunae with
processes in canaliculi directed towards the
PDL
b) Its laminated structure
c) The presence of cementoid on its surface.

39. d : Dentine
c : Cementum
Tgl : Tomes’ granular layer
IF : Intrinsic fibers
EF : Extrinsic fibers
Cy : Cementocyte
AEFC : Acellular Extrinsic Fiber
Cementum
CIFC : Cellular Intrinsic Fiber
Cementum

41. DEFINITION:
Cementoenamel junction represents the anatomic limit between the
crown and root surface and is defined as the area of union of the
cementum and enamel at the cervical region of the tooth.
CEJ is of great importance in
clinics. It helps to deal with
various Peridontal anomalies and
Conservative Dentistry. So, in
order to make it easier,
clinically we deal with two parts
of CEJ:
1) Facial CEJ
2) Interproximal CEJ
Clinical parts of CEJ:

42. Let Us Observe CEJ in a
Radiograph:-

44. TYPES OF CEMENTUM:
CEJ can be classified on the basis of the nature of connections between enamel
and cementum. There are mainly 3 types of cementum:
1) Butt Junction(End-to-end approximating junction)
2) Overlapping Junction
3) Gap Junction

45. *In around 1.6% of cases enamel overlaps Cementum

46. 1) Butt Junction
In approximately 30% of all teeth cementum meets the cervical end
of enamel in a relatively sharp line. This type cemento-enamel junction
where the enamel and the cementum forms an end-to-end junction is
known as Butt Junction.

47. 2) Overlapping Junction
Overlapping junction can be of two types:
a) Cementum overlapping enamel / Cemento-enamel overlapping junction
b) Enamel overlapping cementum / Enamelo-cementum overlapping junction

48. a) Cementum overlapping enamel /
Cemento-enamel overlapping junction
In approximately 60% of teeth, the cementum overlaps the cervical
end of enamel for short distance. This occurs when the enamel
epithelium degenarates at its cervical termination permitting
connective tissue to come in direct contact with enamel surface which
produce a laminated, electron dense, reticular material termed as
afibrillar cementum

49. b) Enamel overlapping cementum junction
 Recent observations by
researchers by optical microscopy
showed fourth type of junction
known as enamel overlapping
cementum junction.
 In this type, CEJ enamel
overlaps cementum.
 However, this type of CEJ is
very rare. It is found only in 1.6%
of cases.

50. 3) Gap Junction
In about 10% of teeth, the cementum and the enamel do not meet.
In such cases there is no cemento-enamel junction. This occurs when
enamel epithelium in cervical portion of roots delayed in the
separation from dentin. In this dentin is an external part of the
surface of the root.

52. DEFINITION:
The terminal apical area of cementum where it joins the internal root
dentin is called cementodentinal junction or CDJ.
The width of CDJ is 2 to 3µm and remains relatively stable.
CLINICAL IMPORTANCE:
The nature of CDJ is of particular importance, being of interest biologically
because it forms an interface (a fit) between two very different mineralized
tissues. It is also of clinical importance because of the processes involved in
maintaining tooth function while repairing a diseased root.
AF: Apical Foramen
AA: Apical Apex

53. DIFFERENCES OF CDJ IN
PERMANENT & PRIMARY DENTITION: