3. Cementum
Derived from dental follicle
Hard, Calcified, avascular mesenchymal tissue
Yellowish in color
Lighter and less harder than dentin
Permeable
The thickness of cementum varies considerably
and the cervical third may be only 16-60 µm
thick
In contrast, the apical third can be 200µm or
even thicker.
3
4. Composition
Organic:- Inorganic:-
50-55% 40-45%
Type 1 Collagen Hydroxyapetite
Fibers and type III Calcium
Collagen fibres Phosphate
Protein
Traces of magnesium
Polysaccharides Fluorides
Water
4
6. Matrix proteins
predominantly of Type I Collagen &
Glycosaminoglycans (Chondroitin sulphate
mainly)
Bone matrix proteins are secreted by
cementoblasts & deposited in cellular
cementum
Osteopontin is concentrated in cement lines
(resting Salter lines).
It mediates cell attachment & cohesion of
matrix molecules at incremental lines
Bone sialoprotien and osteopontin are believed
to play major in differentiation of cementoblasts
progenital cells to cementoblasts
Cementum also contains Growth factors. 6
7. Collagen fibers
two sources
Extrinsic fibers Intrinsic fibers
incorporation of the Produced by
periodontal ligament cementoblast
fibers. Run parallel to root
Also called as surface
sharpey’s fibers
Run in same
direction of principal
fibers
7
10. Acellular cementum Cellular cementum
First formed cementum Formed after acellular cementum
Most of it is formed before the tooth Most of it is formed formed after
reaches occlusal plane tooth reaches occlusal surface
Covers approx the cervical third or Covers the apical third of root
half of the root Contain cementocytes
No cells Less calcified
More calcified Small portion
Sharpey’s fibers make up most of the
structures
May be completely or partially
Completely calcified calcified
10
12. B
A
Cellular cementum (B) overlying acellular cementum
12
13. According to content of fibrils
Fibrillar cementum Afibrillarcementum
Contains well it lacks dense array
defined densely of collagen fibrils
packed collagen although rare
fibrils in it’s matrix. isolated fibrils will be
present.
13
14. According to Schroeder et al
1. Acellular afibrillar cementum
Neither cells nor fibers
Mineralized ground substance
It is a product of cementoblasts
Found as coronal cementum
Thickness of 1-5 µm
14
15. 2. Acellular extrinsic fibre
cementum
Densely packed bundles of sharpey’s fibers
Lacks cells
Product of fibroblast and cementoblast
Found in cervical third
Thickness is between 30-230 µm
15
16. 3. Cellular mixed stratified
cementum
Extrinsic and intrinsic fibers
May contains cells
Co-product of cementoblast and fibroblast
Apical third and furcation areas
100-1000 µm
16
20. 5. Intermediate cementum
Hyaline layer of Hopewell Smith
Poorly defined zone near the cemento-dentinal
junction of certain teeth that appears to contain
cellular remnants of Hertwig’s sheath
embedded in calcified ground substance.
20
21. Intermediate cementum
(layer of calcified tissue
embedded in between
dentin and cementum at
the periphery of dental
roots)
21
22. •Incremental lines of Salter
• These lines represent
the rest periods in
cementum formation
and are more
mineralized than the
adjacent cementum.
• Both cellular and
acellular are arranged in
lamillae seperated by
incremental lines
• These lines are parallel
to the long axis of the
root
•22
24. Pattern 1- Where the cementum overlaps the
enamel for a short distance
Pattern 2- Where the cementum and the
enamel meet at the butt joint.
Pattern 3- Where the cementum and enamel
fail to meet and the dentine is exposed, the
patient may experience hypersensitivity.
24
25. Functions of cementum
Medium of attachment of collagen fibers
that bind to alveolar bone
Continue deposition helps to keep
attachment apparatus intact
Helps in repair of any resorption
25
26. AGE CHANGES IN CEMENTUM
the width of cementum increases with age
Average thickness of 95 µm at age of 20 and
215 µm at age of 60 have been reported
The increase in width is greater in apical and
furcation areas
Permeability of cementum decreases with age.
26
27. HYPERCEMENTOSIS
Refers to non-neoplastic deposition of excessive
cementum that is continuous with the normal
radicular cementum
May be localized to one tooth or affect entire
dentition
Occurs as generalized thickening of cementum, with
nodular enlargement of apical third of root.
27
29. Etiology
Spike like type of hypercementosis
Generally results from excessive tension from ortho
appliances or occlusal forces.
Generalized type occurs in a variety of
circumstances.
In teeth, without antagonist, hypercementosis as an
effort to keep pace with excessive tooth eruption.
Also occurs in teeth subject to low grade peri-apical
irritation arising from pulp disease.
29
30. Factors associated with hypercementosis
can be classified as:
LOCAL SYSTEMIC
FACTORS: FACTORS:
Abnormal occlusal Acromegaly and
trauma, pituitary gigantism.
Unopposed teeth Paget’s disease
(e.g. impacted, Thyroid goitre
embedded, without
antagonist)
Adjacent
inflammation.
30
31. Of these factors, Paget’s disease of bone has
received the most attention.
Numerous authors have reported significant
hypercementosis in patients with Paget’s
disease, and this disorder should be considered
whenever generalized hypercementosis is
discovered in patients with appropriate age.
31
32. Radiographically,affected teeth demonstrate a
thickening or blunting of root, but the exact
amount of increased cementum is difficult to
ascertain because cementum and dentin
demonstrate similar radio-densities.
The enlarged root is surrounded by radiolucent
ligament space and adjacent intact lamina dura.
Premolar teeth are most commonly affected.
32
33. Histologically, the periphery of root exhibits
deposition of an excessive amount of
cementum over the original layer of primary
cementum.
The excessive cementum maybe hypocellular or
exhibit areas of cellular cementum that
resemble bone (osteocementum)
On routine light microcopy, distinction
between cementum and dentin is difficult, but
the use of polarized light clearly separates the
two different layers.
33
34. Hypercementosis itself does not require
treatment
It could cause problem if the affected
tooth requires extraction
In multirooted tooth sectioning of tooth
may be required before extraction
34
35. Cementicles
Globular masses of acellular cementum
generally less than 0.5mm in diameter which
form with in periodontal ligament
exhibit concentric appositional layers of
afibrillar and/or fibrillar cementum
35
36. Types
Free – with in PDL space
Attached- fused to cellular cementum
Interstitial(totally incorporated in the
cementum)
It has been postulated that cementicles
originate from foci of degenerating cell or
epithelial rests in periodontal ligament.
not of clinical significance unless they become
exposed to oral environment where they may
act as sites for plaque retention.
36
38. Cementum Hypertrophy
1- Cemental Hypertrophy:
If overgrowth of cementum improves the
functional qualities of the cementum it is
termed as cementum hypertrophy.
38
40. Cementum Resorption
permanent teeth do not undergo physiological
resorption as do primary teeth
But cementum is subjectede to resorptive
changes that may be of microscopic proportion
or sufficiently extensive to produce a
radiographically detectable alteration in tooth
contour
40
41. Local factors Systemic factors
TFO Calcium deficiency
Ortho movement Hypothyroidism
Pressure from mal-aligned Hereditary fibrous
errupting tooth osteodystrophy
Cyst, tumors Paget’s disease
Teeth without functional
antagonist
Periapical disease
Cause Resorption
41
42. Cementum resorption appears
microscopically as baylike concavities in
the root surface
Multinucleated giant cells and large
mononuclear macrophage3s ar5e
generally found adjacent to cementum
undergoing active resorption
42
43. CEMENTAL REPAIR
Cementum resorption is not necessarily continous
After resorption has ceased, the damage is usually
repaired, either by formation of acellular or cellular
cementum or by alternate formation of both.
The newly formede cementum is demarcated from the
root by a deeply staining irregular line termed as
reversal line
In most cases of repair there is a tendency to re-
establish the former outline of the root surface.
This is called anatomic repair.
43
44. However, if only a thin layer of cementum is
deposited on surface of deep resorption, the
root outline is not reconstructed and a bay like
recess remains.
In such cases, some time the periodontal space
is restored to it’s normal width by formation of
bony projections so that proper functional
relationship will result.
The outline of the alveolar bone in these cases
follows that of the root surface. In contrast to
anatomic repair, this change is called functional
repair.
44
46. Ankylosis:
Fusion of cementum and alveolar bone with
obliteration of the periodontal ligament is
termed as ankylosis
Ankylosis occurs in teeth with cemental
resorption which suggests it may represent a
form of abnormal repair
Other causes of ankylosis include tooth
reimplantation,occlusal trauma,after chronic
periapical inflammation and around embedded
teeth
46
47. Ankylosis results in resorption of the
root and its gradual replacement by bone
tissue.for this reason reimplanted teeth
that ankylose will loose their roots after
4 to 5 years and will be exfoliated
47
48. Clinical features of ankylosed teeth
They lack the physiological mobility of
normal teeth(this is one of the diagnostic
signs for ankylotic resorption)
Teeth have special mettalic percussion
sound
Teeth may be in infraocclusion
48
49. Changes in ankylosed teeth
As the periodontal ligament is replaced with
bone in ankylosed teeth proprioception is lost
coz pressure receptors in the periodontal
ligamentb are deleted or do not function
correctly
Physiological drifting and eruption of teeth can
no longer occur and thus the ability of the
teeth and peridontium to adapt to altered
force levels or directions of force is greatly
reduced
49
51. oEXPOSURE OF CEMENTUM TO
ORAL ENVIRONMENT
o Cementum becomes exposed to oral
environment in cases of gingival
recession and as a result of loss of
attachment in pocket formation
o This may lead to cemental invasion by
bacteria
o Cementum caries can also develop
o51
54. CONCLUSION
Cementum is probably the least understood of
all dental tissues.
But this does not lessen it’s role in the
periodontal attachment apparatus.
With the development of newer concepts of
regenerative cementogenesis and role of
cementum in implants, the need for us to
better understand this basic tissue should be
understood and implemented.
54
55. References
Caranza’s clinical periodontology
Orban’s dental anatomy and histology
Bath, M., Balogh, M. & Fehrenbach, M. J. (1997) Dental
Embryology, Histology, and Anatomy, 1st ed., W.B
Saunders, Pennsylvania.
Bath, M., Balogh, M. & Fehrenbach, M. J. (2006) Dental
Embryology, Histology, and Anatomy, 2nd ed., W.B
Saunders, Pennsylvania.
Oral antomy, histology and embryology by berkovitz,
G.R. Holand and Moxham
Shafer’s oral pathology,
Internet sources
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