Cementum is the mineralized dental tissue covering the anatomical root of teeth. It begins at the cervical portion of the tooth at the cementoenamel junction till the apex. It is one of the four tissues that support the tooth in the jaw (the periodontium). The primary function- Provides attachment to collagen fibres of the periodontal ligament. It therefore is a highly responsive tissue maintaining the integrity of the root, helping to maintain the tooth in its functional position in the mouth, and being involved in tooth repair and regeneration.

1. CEMENTUM

2. INDEX
 Physical properties
 Chemical properties (Composition)
 Cellular and Acellular cementum
 Schroeder classification of cementum
 Functions of cementum
 Cementogenesis, Cementoblasts, Cementocytes
 Cementoenamel Junction
 Cementodentinal Junction
 Repair and Resorption of Cementum
 Age changes
 Clinical Considerations

3. INTRODUCTION
 Cementum is the mineralized
dental tissue covering the
anatomical root of teeth.
 It begins at the cervical
portion of the tooth at the
cementoenamel junction till
the apex.
 It is one of the four tissues
that support the tooth in the
jaw (the periodontium).

4.  The primary function- Provides attachment to collagen
fibres of the periodontal ligament.
 It therefore is a highly responsive tissue maintaining the
integrity of the root, helping to maintain the tooth in its
functional position in the mouth, and being involved in
tooth repair and regeneration.
 Avascular

5. PHYSICAL CHARACTERISTICS
 It is the least in hardness in comparison to enamel, and dentin. This
hardness is on account of the mineralization of cementum, which is around
45 to 50%; whereas the mineralization of enamel is around 96%; and that of
dentin is around 65%.
 Cementum is pale yellow in colour, having a dull surface. It is lighter in
colour than dentin.

6. PHYSICAL CHARACTERISTICS
 Cementum being avascular, no capacity to remodel.
 Cementum deposition is a continuous process that proceeds at varying rates
throughout life. The formation of cementum is most rapid
 At the apical regions due to continuous attrition.
 On the distal surfaces, probably because of functional stimulation, from the
mesial drift over time.

7.  The thickness of the cementum on the coronal half of the root
varies from 16 to 60 µm and 150 to 200 µm in the apical 3rd and
in the furcation areas.
 Why abrasion occurs in cervical region?
Softness of cementum, combined with its thinness cervically,
means that it is readily removed by abrasion when gingival
recession exposes the root surface to the oral environment. Loss
of cementum in such cases will expose the dentin.

8. CHEMICAL PROPERTIES (COMPOSITION)
INORGANIC
MATRERIAL-
65%
ORGANIC
MATERIAL-23%
WATER-12%
On a net weight basis, cementum consists of

9. By volume, cementum consists of
INORGANIC
MATRERIAL-
45%
ORGANIC
MATERIAL-33%

10. INORGANIC COMPONENT
 Mainly consists of calcium and phosphate in the form of
hydroxyapatite.
 Highest level of fluoride of all mineralised tissues. The
fluoride levels are higher in acellular than cellular
cementum.
 Trace elements like magnesium, copper, iron, lead,
potassium, silicon, sodium, zinc etc. are also found.
 As with enamel, the concentration of the trace elements
appears to be higher at the surface.

11. ORGANIC COMPONENT
Type I
collagen
fibers
Glycosamin-
oglycans like
chondroitan
sulphate,
dermatan
sulphate,
heparin
sulphate and
hyaluronate
Adhesion
molecules
like tenascin
and
fibronectin
Interfibrillar
ground
substance
consists of
proteoglycans

12. STRUCTURE OF CEMENTUM
With the light microscope, two kinds of cementum can be
differentiated
ACELLULAR
CEMENTUM
CELLULAR
CEMENTUM
CEMENTUM

13. ACELLULAR CEMENTUM/ PRIMARY
CEMENTUM
 Donot contain any cells (spiderlike cementocytes) so called as
the acellular cementum.
 Thickness -30 to 230 µm.
 Covers root dentin from the cementoenamel junction to the apex,
but is often missing on the apical third of the root.
 FUNCTION:
 Provides attachment for the tooth.
 Sharpey’s fibers comprise most of the structure of acellular
cementum, which has a principal role in supporting the tooth.
 This is the first formed cementum. It is formed before the tooth
surface reaches the occlusal plane. Hence it is also called as the
primary cementum.

14. CELLULAR CEMENTUM/ SECONDARY
CEMENTUM
 It contains cells, called as cementocytes, in individual spaces
(lacunae),which communicate with each other through a system
of anastomosing canaliculi.
 FUNCTION: It has an adaptive role in response to tooth wear
and movement and is associated with repair and regeneration of
periodontal tissues.
 Sharpey’s fibres occupy a small portion of the cellular
cementum.
 This is formed after the tooth reaches the occlusal plane. Hence,
it is also called as the secondary cementum
 It is more often seen on the apical half of the root.

15. DIFFERENCES BETWEEN CELLULAR
AND ACELLULAR CEMENTUM
CELLULAR CEMENTUM ACELLULAR CEMENTUM
 generally present in apical segment
of the root.
 Contains more number of
cementocytes in the matrix.
 This has a greater proportion of the
intrinsic fibres (secreted from
cementoblasts) and about 40 to 60%
collagen matrix derived from the
ligament collagen.
 The extrinsic fibres present are
generally mineralized only on the
periphery and have an unmineralized
core.
 generally present at the cervical
third of the root and over the
dentinal surface
 The acellular cementum contains
less number of the cementocytes,
that are distantly apart.
 It has majority of the the extrinsic
fibers.
 The fibers present on the
acellular cementum are generally
fully mineralized; and called
Sharpeys fibers

16. SCHROEDER’S CLASSIFICATION
OF CEMENTUM
ACELLULAR AFIBRILLAR CEMENTUM
(AAC)
ACELLULAR EXTRINSIC FIBER
CEMENTUM (AEFC)
INTERMEDIATE CEMENTUM
CELLULAR INTRINSIC FIBER CEMENTUM
CELLULAR MIXED STRATIFIED
CEMENTUM

17. ACELLULAR AFIBRILLAR CEMENTUM
(AAC)
 This type of cementum does not contain cells and fibers
(intrinsic and extrinsic fibers).
 It is a product of cementoblasts and is found mainly in the
coronal portion, near to the cementoenamel junction.
 Its formed in the regions where the connective tissue comes in
contact with the enamel during tooth development.
 The thickness of this type of cementum is 1 to 15 µm.

18. ACELLULAR EXTRINSIC FIBER
CEMENTUM (AEFC)
 Composed almost entirely of densely packed bundles of
sharpey’s fibers and lacks cells.
 It is found in the cervical third of roots but may extend
further apically.

19. CELLULAR MIXED STRATIFIED
CEMENTUM
 It is composed of extrinsic as well as intrinsic
fibers and contains many cells.
 It is a co-product of fibroblasts and cementoblasts
.
 It is found in the apical third of the roots and in the
furcation areas.
 This constitutes the bulk of secondary cementum.
 With the organization of the periodontal ligament,
further deposition of cellular cementum
incorporates ligament fiber bundles of the PDL,
thereby creating secondary mixed fiber
cementum.

20. CELLULAR INTRINSIC FIBER CEMENTUM
 It contains cells but no extrinsic collagen fibers.
 It is formed by cementoblasts, and it fills the
resorption lacunae .
 Although the intrinsic fiber cementum does not
alone have any immediate function in tooth
attachment, it is important as an adaptive tissue.
 In addition only cellular intrinsic fiber cementum
can repair resorptive defects of the root in a
reasonable time due to its capacity to grow
much faster than any other known cementum
type.

21. INTERMEDIATE CEMENTUM
 The first layer of cementum is actually formed
by the inner cells of the HERS (Hertwigs
epithelial root sheath) and is deposited on the
root’s surface, and this is called the intermediate
cementum or Hyaline layer of Hopewell-Smith.
 Deposition occurs before the HERS
disintegrates. It seals off the dentinal tubules.
 Intermediate cementum is situated between the
granular dentin layer of Tomes and the
secondary cementum that is formed by the
cementoblasts .
 It mineralizes greater than the adjacent dentin
or the secondary cementum.

22. FUNCTIONS OF CEMENTUM
• It has the principle function of providing a medium for the attachment to the
collagen fibers of the periodontal ligament.
• To maintain the occlusal functional relationship of the teeth, done by the
apical cementogenesis
• Cementum has no blood supply, and does not show resorption under masticatory or
orthodontic forces. Thus during heavy orthodontic forces, tooth integrity is maintained
and alveolar bone being elastic in nature,changes its shape.
• As a seal for the open dentinal tubules. By providing this seal it prevents
sensitivity that can occur on dentinal exposure .
• Cementum has the property of continuous deposition and does the
patchwork or repair for the damaged root, such as fracture or resorption of
the root surface.

23. CEMENTOGENESIS
 Cementogenesis is the formation of cementum.
 Hertwig's epithelial root sheath fragment.
 Then the dentin, comes in contact with the dental sac.
This then stimulates the activation of cementoblasts to
begin cementogenesis.
 Some sheath cells migrate away from the dentin towards
the dental sac, whereas others remain near the developing
tooth and are ultimately incorporated into the cementum.
 Sheath cells that migrate towards the dental sac, become
the epithelial rests of Malassez, found in the periodontal
ligament of fully developed teeth.

24. CEMENTOBLASTS
 Soon after Hertwig’s root sheath breaks up,
undifferentiated mesenchymal cells from adjacent
connective tissue differentiate into cementoblasts.
 These cells then align themselves along the external
surface of the dentin.
 Cementoblasts synthesize collagen and protein
polysaccharides (proteoglycans), which make the
organic matrix of cementum.
 These cells have numerous mitochondria, a well-
formed Golgi apparatus, and large amounts of
granular endoplasmic reticulum.

25. CEMENTOCYTES
 These cells are incorporated into the cellular cementum,
and are similar to osteocytes. They lie in the spaces
designated as lacunae.
 They have less cytoplasmwith a centrally located n
ucleus.
 The cytoplasm of these cells contains few organelles,
the endoplasmic reticulum appears dilated, and the
mitochondria are also very less.
 They have numerous cell processes, or canaliculi,
radiating from its cell body. These processes may
frequently anastomose with those of the neighboring
cells.

26. CEMENTOID TISSUE
 Under normal conditions, growth of cementum is a
rhythmic process, and as a new layer of cementoid is
formed, the old one calcifies.
 A thin layer of cementoid can usually be observed on
the cemental surface. This cementoid tissue is lined
by cementoblasts.
 The cementoid tissue begins initially at the
cementodentinal junction, and persists for the life of
the tooth as the outermost layer of the cemental
matrix.
 The cementoid provides a compatible environment for
the cementoblasts and serves a protective function, in
that, it resists cementoclasia or cementum resorption.
 The width of the cementoid layer ranges from the 3 to

27. INCREMENTAL LINES
 The growth pattern of cementum is not continuous and
may generally vary from time to time.
 Both the cellular and acellular cementum, are separated
by incremental lines, into layers, which indicate periodic
formation.
 They can be used for estimation of age.

28. TYPES OF CEJ
 Pattern I- where the cementum overlaps the enamel for a
short distance, is the predominant arrangement in 60% of
sections. This occurs when the enamel epithelium
degenerates at the cervical end, allowing the connective
tissue to come in direct contact with enamel surface
 Pattern II- where the cementum and enamel meet at a
butt joint, occurs in 30% of sections.
 Pattern III- where the cementum and enamel fail to meet
and the dentin between them is exposed, occurs in 10%
of sections. This occurs when enamel epithelium in the
cervical portion of the root is delayed in its separation
from dentin

30. CLINICAL SIGNIFICANCE OF THE
CEMENTOENAMEL JUNCTION
DETERMINING THE LEVEL OF ATTACHMENT:
.
When the gingival margin is located on the anatomic crown, the level of
attachment is determined by subtracting from the depth of the pocket the
distance from the gingival margin to the cementoenamel junction. If both
are the same, the loss of attachment is zero.

31. When the gingival margin coincides with the cementoenamel junction, the
loss of attachment equals the pocket depth.

32. When the gingival margin is located apical to the cementoenamel junction, the
loss of attachment is greater than the pocket depth and therefore the distance
between the cementoenamel junction and the gingival margin should be added
to the pocket depth

33. CEMENTODENTINAL JUNCTION
 The cementodentinal junction is an interface between
two very different mineralised tissues that are developing
contemporarily.
 The dentin surface upon which cementum is deposited
is relatively smooth, in permanent teeth.
 The cementodentinal junction in the deciduous teeth is
scalloped. The attachment of cementum to dentin in
either case is quite firm
 Since collagen fibrils of the cementum and dentin
intertwine at their interface in a very complex fashion, it is
not possible to precisely determine which fibrils are of
dentinal and which are of cemental origin.
 It is often reported that an ‘intermediate layer’ exists
between cementum and dentin.
 When an intermediate layer is present, it has been
suggested this functions as a permeability barrier, that it
may be a precursor for cementogenesis, and that it is a
precursor for cementogenesis in wound healing. These

34. CEMENTODENTINAL JUNCTION
 The cementodentinal junction is an interface
between two very different mineralised tissues.
 The dentin surface upon which cementum is
deposited is relatively smooth, in permanent
teeth.
 The cementodentinal junction in the deciduous
teeth is scalloped.

35. REPAIR AND RESORPTION OF
CEMENTUM
 Cementum resorption may be caused by:
 Local or
 Systemic factors, or maybe
 Idiopathic(i.e. of unknown etiology).

36. LOCAL FACTORS
Trauma from occlusion
Pressure from malaligned erupting
teeth
Excessive Orthodontic forces
Teeth without functional antagonists
Cyst and tumors
Embedded teeth
Replanted teeth and transplanted teeth
Periodontal disease.
Periapical disease

37. SYSTEMIC FACTORS
Calcium deficiency
Hereditary fibrous osteodystrophy
Hypothyroidism
Paget’s disease.

38. REPAIR OF CEMENTUM
 Repair of cementum is a process to heal the damage caused
by resorption or cemental fracture.
 Repair may be anatomic or functional.
 In most cases of repair, there is a tendency to re-establish the
former outline of the root surface. This is called as the
anatomic repair. It generally occurs when the degree of
destruction is low.
 In cases of large areas of cemental resorption or destruction,
repair does not re-establish the same anatomic contour as
before, because only a thin layer of cementum is deposited
over the concavity created by the cemental resorption. To
maintain the width of the periodontal ligament, the adjacent
alveolar bone grows and takes the shape of the defect
following the root surface. This is done to improve the function
of the tooth, thus called as the functional repair.

39. AGE CHANGES IN CEMENTUM
 With aging, the relatively smooth surface of cementum
becomes more irregular. This is caused by the
calcification of some fiber bundles where they were
attached to the cementum. Such occurrences appear on
most surfaces of the cementum, but they occur rarely
near the apical zone.
 An increase in the width of cementum is a common
finding; this increase may be 5 to 10 times with
increasing age. This finding is not surprising because
deposition continues after the tooth eruption .The
increase in width is greater apically and lingually.
 In aging, a continuous increase of cementum in the

40. CLINICAL CONSIDERATIONS
HYPERCEMENTOS
IS
 It is the abnormal
thickening of the
cementum.
 It may be diffuse or
circumscribed. It may
affect all the teeth of
the dentition, or it may
be confined to a single
tooth, or even affect
only parts of one tooth.
 It may be either
localised or
Radiographic appearance of
maxillary posterior teeth with
evidence of hypercementosis.

41. CEMENTICLES
 These are the calcified bodies sometimes seen in the
periodontal ligament.
ORIGIN
 Cementicles may develop from calcified epithelial rests
 Around small spicules of cementum or alveolar bone
traumatically displaced into the periodontal ligament
 From calcified Sharpey's fibers
 From calcified thrombosed vessels within the periodontal
ligament.

42. TYPES OF CEMENTICLES:
 Free cementicles : These are lamellated cemental bodies
that lie freely
in the periodontal ligament.
 Attached cementicles: These are the cemental bodies
which are attached
to the root surface.
Other than these, there are the imbedded cementicles within
a thick layer of cementum.
Sessile cementicles may mimic calculus, once they are
exposed, and serve as promoters of periodontal disease.
Imbedded cementicles have no clinical relevance and are
merely of academic interest.

43. ORTHODONTIC TOOTH MOVEMENT
 Cementum is more resistant to resorption than is bone, and it
is for this reason that orthodontic tooth movement is made
possible.
 When a tooth is moved by means of an orthodontic
appliance, bone is resorbed on the side of the pressure, and
new bone is formed on the side of tension.
 Cementum resorption is minimal or absent but bone
resorption leads to tooth migration.
 The difference in the resistance of bone and cementum to
pressure may be caused by the fact that bone is richly
vascularised, whereas cementum is avascular.

44. ANKYLOSIS
 When there is fusion of cementum and the alveolar
bone, with no periodontal ligament in between, it is
known as ankylosis.
 In ankylosis, there is resorption of the root, and its
replacement by bone.
 Before performing an extraction of any firm tooth,
its radiograph must be taken. In case of any
ankylosis of the tooth, while attempting an
extraction, fracture of the tooth or bone may occur.

45. CAUSES OF
ANKYLOSIS
Replantation
and
transplantation
of teeth, cases
in which
periodontal
ligament is
damaged.
Embedded
teeth.
Chronic
periapical
infection.
Trauma to
deciduous
teeth – leading
to destruction
of the dental
follicle of the
underlying
developing
permanent
tooth germ,
causing its
ankylosis.

46. ANOMALIES DURING CEMENTOGENESIS
 Anomalies in cementogenesis may have significant
clinical implications.
 For example, enamel pearls often mimic
subgingival calculus deposits and may lead to
similar patterns of periodontal tissue destruction.
 Enamel projections may lead to pockets in
furcations.
 Neither enamel pearls, nor enamel projections can
be removed by scaling. Their removal necessitates
grinding the enamel off the root surface.
 Hypercementosis may interfere with tooth
extractions.

47. CERVICAL ENAMEL PROJECTIONS
 Cervical enamel projections are flat, ectopic
extensions of enamel that extend beyond the
normal contours of the cementoenamel
junction.
Classification of cervical enamel projections:
 It was given by Masters and Hoskins in the
year 1964.
 Grade I – The enamel projection extends
from cementoenamel junction of the tooth
towards the furcation.
 Grade II – The enamel projection
approaches the entrance to the furcation. It
does not enter the furcation, therefore there
is no horizontal component .
 Grade III – The enamel projection actually
extends horizontally in to the furcation.

48. ENAMEL PEARLS
 If the cells of the hertwig’s
epithelial root sheath remain
adherent to the root surface,
they may differentiate into fully
functioning ameloblasts, and
produce enamel .
 Such droplets are the enamel
pearls.
 Enamel pearls are less
frequent than the cervical
enamel projections.
 They interfere with the
attachment apparatus and may
prevent regenerative

49. FRACTURE OF ROOT
 This fracture may be vertical or horizontal.
 The tooth with vertical fracture has poor prognosis
and usually it cannot be repaired by cementum easily.
 It should be extracted or stabilized by intracoronal
splinting or banding.
 The tooth with horizontal fracture, depending upon
the location of the fracture line and the age of the
patient has a variable prognosis .
 If the fracture is at the apical and the middle third of
the root of the young patient, then it can be repaired
by cementum and prognosis of the vitality of the pulp
of the tooth for the survival is fair

50. AS A LANDMARK DURING ROOT
CANAL TREATMENT
 Where root canal exits the apex of the tooth,
cementum is deposited not only over the apex, but
also for a short distance, usually 0.5 to 1.5 mm from
the anatomical apex.
 This results in narrowing of the apical constriction.
 This represents the junction of the pulp and
periodontal tissue.
 In clinical procedures of root canal treatment, for the
removal of diseased pulp tissue, this is the point up
to which cleansing is done.

51. IMPORTANCE OF ROOT PLANING IN
PERIODONTAL TREATMENT
 Root planing is a process by which residual
embedded calculus and portions of cementum are
removed from the roots to produce a
smooth,hard,clean surface.
 In case of deep pockets, surface of the cementum
exposed in the pockets becomes hypermineralized
and the endotoxins are produced by the plaque
bacteria which are incorporated in to the cementum.
 These endotoxins cause structural changes in
cementum and may interfere in healing process
during periodontal treatment.
 Root planing removes hypermineralized necrotic

52. CONCLUSION
 Cementum is a calcified tissue which has properties comparable with that
of bone.
 It plays an important role in the attachment apparatus of the tooth and has
an important role in orthodontic tooth movement.
 Cementum deposition is a continuous process and it can not remodel
because of the lack of vascular supply.
 It has got the properties of resorption and repair.