Cementum is the calcified tissue that covers the anatomical root of teeth. It serves as the medium of attachment for collagen fibers that bind the tooth to surrounding structures. Cementum resembles bone in its physical and chemical structure but is avascular, non-innervated, and unable to remodel. There are two main types - acellular cementum found in the coronal root and cellular cementum found apically, which contains cementocytes. Cementum is formed by cementoblasts and undergoes continuous formation throughout life to maintain attachment and compensate for attrition.

2. Cementum

3. By
Professor of Oral Biology
Faculty of Oral and Dental Medicine
Cairo University

4. Cementum is a specialized calcified dental
tissue covering the anatomical root of human
teeth.
 Cementum serves as a medium of attachment of
the colagen fibers that bind the tooth to the
surrounding structures.
 Cementum resembles bone in some of its physical
and chemical structures , however, it is :
 Avascular
 Not innervated
 Unnable to remodel

5. Physical Characteristics
1-Color
Light yellow
Lighter in color than dentin,
darker than enamel
2- Thickness
Acellular cementum (20-50 m)
Cellular cementum (150-200 m)
3- Permeability
Permeable from dentin and PDL sides.
Cellular C is more permeable than acellular C.

6. Chemical Composition
45-50 % Inorganic
substances
50-55% Organic
substances
Hydroxyapatite
crystals Collagen
Polysaccharides
Less harder than dentin&
much less harder than
enamel
Cementum contains the greatest amount of
fluoride in all mineralized tissues.

7. Histological Structure

8. Cementoblasts
•Large cuboidal cells
•Found on the surface of both
celular and acellular
cementum.
•They produce collagen fibers
(intrinsic fibers) and ground
substance of cementum.

9. Cementoblast is a protein forming and secreting cell.
Large open face nucleus
R E R
Golgi apparatus
Mitochondria
Secretory granules
Alkaline phosphatase

10. Cementocytes
 They are incorporated in
cellular cementum
 Spider shape appearance
 They have numerrous
irregular processes.
 Most processes are
directed towards PDL.
Dentin PDL

11. The cell body is located in a space called lacuna and
their processes are present in canaliculi
Cementocytes in deeper layers of cementum undergo
degeneration and gradually lose their organelles and
die
Dentin PDL

12. In ground section, cementocytes spaces
appear as dark spaces

13. Cementocyte And Osteocyte
Dentin side
Lacuna
PDL side
Canaliculi
Osteocyte

14. Collagen fibers of cementum are derived
from two sources:
A- The embedded part of PDL fibers( Sharpys fibers, this
is formed by PDL fibroblasts and called extrensic
fibers.
B- Other fibers are formed by osteoblast and are called
intrinsic fibers.
Extrensic fibers are short and dense arranged
perpendicular to root surface.
Intrinsic fibers are arranged parallel to the root surface.

15. Types Of Cementum

16. 1- Acellular ementum 2- Cellular cementum
3- Intermediate cementum 4- Afibirllar cementum

17. Acellular Cementum
 Thickness is 20-50 μm.
 It is clear and structureless
 Incremental lines of Salter
are parallel to the surface.
 Sharpey’s fibers space can
be seen in it .

18. The bulk of collagen fibers are derived from
Sharpys fibers , so it is called acellular extrinsic
fiber cementum.
 This the only type found in incisors and
extend to the apical foramen.
 It is found in the coronal part of the root of the
premolars and molars roots.

19. Cellular Cementum

20. •It is found at the apical third and the furcation area of
premolars and molars.
 Thickness increase gradually till root apex reaching
150- 200 μm
 It is formed faster than acelular cementum.
 It is more permeable than acelular cementum.
•It is formed mainly of intrinsic fibers ( Intrinsic fiber
cementum).
•It contains cementocytes ( Imprisoned cementoblasts).

21.  In decalcified sections,
the lacnae appears as
minute space
containing the
cementocytes
 In ground section, the
lacunae of cementocytes
appear black as they
are filled with air after
desentigration of the
cells during preparation

22. Some cementoblasts become entrapped in the forming
matrix and then known as cementocytes

23. Incremental Lines Of
Salter
• IL are faint lines run parallel to the root surface
In acellular C, less
distance between IL
In cellular C,more
distance between IL
They are hypermineralized area with less collagen
fibers and more ground substance

24. Intermediate Cementum
Premature
degeneration of
epith. Root sheath
of Hertwig ( after
odontoblasts
differentiation and
before dentin
formation)
Contains entrapped
epithelial cells&
intrinsic fibers
It occur at apical 2/3 of premolars and molars
roots and rare in incisors and deciduous teeth

25. Cemento Dentinal Junction
 It is not distinctive,
because the Fibers of
dentin and cementum
intermingle at the
interface
C
D

26. Cemento Dentinal Junction
Smooth in permanent
teeth
Scalloped in deciduous
teeth

27. Cemento Enamel Junction
30% cementum
meets the enamel
in a sharp line
10% cementum and enamel
doesn’t meet because of
delayed separation of epith
root sheath of Hertwig (area
of dentin not covered by C).
60%
cementum
overlaps E
(afibrillar
cementum)

28. Afibrillar Cementum
The enamel at cervical
area not covered by
reduced dental
epithelium before
tooth eruption
The connective tissue of
the dental sac lay down
cementum on the
exposed enamel

29. Functions Of Cementum
1- It occludes sensitive dentin
2- Acts as a medium for attachment
of collagen fibers of PDL
(Sharpey’s fibers).
3- The continuous formation of
cementum keeps the attachment
apparatus intact.

30. 4- Cementum deposition
epically compensate for
the attrition.
5- It is a major reparative
tissue ( as in case of
fracture or resorption of
root)

31. Cementogenesis
 1- Matrix formation  2- Maturation
Collagen
fiber type I
Ground
substance
Hydroxy apatite
crystals

32. 1- Matrix formation
 Cementum is formed
during root formation
Future C E J Epith. Diaph.
H E R
D
Cementoblasts

33. Cementoblast is a protein forming and secreting cell.
D
Cementoblast
Collagen fibers +
ground substance.
Cementum
Large open face nucleus
R E R
Cementoid layer
Golgi apparatus
Mitochondria
Secretory granules
Cementoblasts
Alkaline phosphatase

34. Resorption of cementum
•Normal phenomena in deciduous
teeth .
Certain factors as trauma or
sustained pressure can result in
resorption of cementum.

35. Age Changes Of The Cementum

36. Cementum formation is continuous throughout life
in a very slow rate Especially in apically and in the
furcation area.
The rate of formation may vary from time to time .
D
D
1- Hypercementosis.
Localised
May affect one tooth or all teeth Hypercementosis

37. Types Of Hypercementosis
Hypercementosis
hyperplasia
Hypercementosis
hypertrophy
Increase number of
Sharpey’s fibers
Decrease number of
Sharpey’s fibers

38. 2- Permeability
From
periodontal
side, but remain
at the
superficial
recently formed
layers
From dentin
side
remains at
apical area
ONLY

39. Cementicles
 Calcified oval or round nodules
found in the PDL, single or in
groups.
 The origin may be calcified epith.
Cells (Rests of Mallasez).
 They may be free or attached or
impedded in cementum.