7. Its primary function is to provide attachment to
the fibers of the periodontal ligament to the
roots of the teeth.
first demonstrated microscopically in 1835 by
two pupils of Purkinje.
begins at the cervical portion of the tooth at the
CEJ and continues to the apex of the root.
8. It is also known as Substantia Ossea
It is yellow in colour and is derived from the
dental follical.
Unlike bone, it is avascular and does not have
the ability to remodel and is generally more
resistant to resorption than the bone.
9. CEMENTOGENESIS
During tooth development the dental papilla gives
rise to odontoblasts and the dental pulp while the
dental follicle gives rise to Cementum, PDL and
alveolar bone.
For cementogenesis to begin the Hertwig’s
epithelial root sheath must fragment.
Once the root sheath disintegrates the underlying
newly formed dentine comes in contact with the
undifferentiated cells of the dental follicle.
10. This stimulates the activation of
cementoblasts which lay down the matrix
and begin cementogenesis.
12. ORGANIC COMPONENTS
Water-12%
Organic- 23% and Inorganic-65%
Type I collagen (up to 90%of organic content)
and protein polysaccharides (proteoglycans).
Other collagen associated with cementum
include type III, V, VI and XII.
13. Non-Collagenous proteins include–alkaline
phosphate, bone sialoprotein, fibronectin,
osteocalcin, osteonectin, Osteopontin,
proteoglycans, vitronectin and several growth
factors.
14. CELLS OF CEMENTUM
Cementoblasts : They synthesize collagen
and protein polysaccharides that form the
organic matrix of Cementum.
Cementocytes: During the formation of
Cementum, some cementoblasts become
incorporated into the cemental matrix. These
cells lie in spaces known as lacunae.
15. FIBERS OF CEMENTUM
Extrinsic: They are incorporation of the
periodontal ligament fibers also known as
SHARPEY’S fibers. They run in the same
direction as the principle fibers.
Intrinsic: They are produced by
cementoblasts and run parallel to the root
surface.
17. ACELLULAR CEMENTUM
It is first to be formed & covers approximately
the cervical third or half of the root.
It does not contain any cells.
This cementum is formed before the tooth
reaches the occlusal plane.
Its thickness ranges from 30 to 230 µm.
18. Sharpey’s fibers comprises most of the
structure of acellular cementum, which has a
principal role in supporting the tooth.
Most fibres are inserted at approximately right
angles into the root surface & penetrate deep
into the cementum, while others enter from
several different directions.
20. Size, number & distribution of acellular
cementum increases with the function of teeth.
Sharpey’s fibers are completely calcified in
acellular cementum, with the mineral crystals
oriented parallel to the fibrils as in dentin &
bone.
In 10 – 50 µm wide zone near cementodentinal
junction, sharpey’s fibers are partially calcified.
21. CELLULAR CEMENTUM
It is formed after the tooth reaches the occlusal
plane.
It is more irregular and contains cells within its
matrix called cementocytes.
The cementocytes are present in individual
spaces called lacunae that communicate with
each other through a system of anastomosing
canaliculi.
22. It is less calcified than the acellular cementum.
Sharpey’s fibers make up a smaller portion of
cellular cementum and are separated by collagen
fibers.
Sharpey’s fibers may be completely or partially
calcified.
It may have a central, uncalcified core surrounded
by a calcified border.
23. Both acellular & cellular cementum are
arranged in lamellae separated by incremental
lines parallel to the long axis of the root
(Incremental lines of Salter).
These lines represent “rest periods” in
cementum formation & are more mineralized
than the adjacent cementum.
24. Based on these findings, Schroeder has
classified cementum as follows:
ACELLULAR
AFIBRIL
ACELLULAR
EXTRINSIC
FIBER
CELLULAR
MIXED
STRATIFIED
CELLULAR
INTRINSIC
FIBERS
INTERMEDDIATE
25. ACELLULAR AFIBRILLAR CEMENTUM
(AAC)
No cells, no extrinsic fibers, no intrinsic fibers,
except for a mineralized ground substance.
It is a product of Cementoblasts. It is found in
coronal cementum with a thickness of 1 to
15µm.
26. ACELLULAR EXTRINSINC FIBER CEMENTUM
(AEFC):
Composed entirely of densely packed bundles
of sharpey’s fibers.
Lack cells. Its thickness is between 30 to
230µm.
It is a product of fibroblasts & cementoblasts.
It is found in the cervical third of roots in
27. CELLULAR MIXED STRATIFIED CEMENTUM
(CMSC):
Composed of extrinsic, intrinsic fibers and
cells.
co product of fibroblasts and Cementoblasts.
Appears primarily in the apical third of the
roots, the apices and the Furcation areas.
Its thickness ranges from 100 to 1000µm.
28. CELLULAR INTRINSINC FIBER CEMENTUM
(CIFC):
It is composed of cells but no extrinsic collagen
fibers.
It is a product of Cementoblasts.
It fills resorption lacunae.
29. 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.
30. PERMEABILITY OF
CEMENTUM
In very young animals, acellular & cellular
cementum are very permeable & permit the
diffusion of dyes from pulp & external root
surface.
In cellular cementum the canaliculi in some
areas are contiguous with dentinal tubuli.
The permeability of cementum diminishes with
age.
32. Three types:
In about 60% to 65% cases cementum overlaps
enamel.
In about 30% cases an edge to edge butt joint
exists.
In about 5% to 10% cases enamel and cementum
fail to meet. In such cases gingival recession may
result in sensitivity due to exposed dentine
33. CEMENTODENTINAL
JUNCTION
The terminal apical area of cementum where it
joins the internal root canal dentin.
When root canal treatment is performed, the
obturating material should be at CDJ.
No increase or decrease in the width of CDJ
with age; its width appears to remain relatively
stable; it is 2 to 3µm wide.
34. THICKNESS OF CEMENTUM
Cementum deposition is a continuous process
that proceeds at varying rates throughout life.
It is more rapid in apical regions, where it
compensates for tooth eruption, which itself
compensates for attrition.
Thickness of cementum on the coronal half of
root varies from 16 to 60µm.
35. It attains its greatest thickness in apical third &
in furcation areas(upto 150 – 200m).
It is thicker in distal surfaces than in mesial
surfaces because of functional stimulation from
mesial drift over time.
36. AGE CHANGES IN
CEMENTUM
Decreased permeability of cementum
Width of cementum increases with age;
greater at the apical and furcation areas. This
may cause obstruction of apical foramen.
The surface of cementum becomes irregular
due to calcification of fiber bundles attached to
the surface.
38. It refers to a prominent thickening of
cementum.
It occurs as a generalized thickening of
cementum, with nodular enlargement of apical
third of root.
It appears in the form of spike like
excrescences created by either coalescence
of cementicles that adhere to the root or
calcification of periodontal fibers at the site of
CLINICAL
FEATURES:
39. RADIOGRAPHIC FEATURES:
Radiolucent shadow of periodontal ligament.
Radiopaque lamina dura seen on outer border
of an area of hypercementosis.
40. ETIOLOGY:
The spike like type of hypercementosis results
from excessive tension from orthodontic
appliances or occlusal forces.
Generalized hypercementosis occurs in teeth
without antagonists & Paget’s disease.
Cementum is deposited adjacent to inflamed
periapical tissue.
41. Some important other systemic condition where
generalized Hypercementosis can be seen:
1. Acromegaly
2. Arthritis
3. Calcinosis
4. Rheumatic fever
5. Thyroid goiter
42. CEMENTICLES
These are globular masses of acellular
cementum
Generally less than 0.5mm in diameter, round
lamellated cemental bodies that may lie free or
attached within the periodontal ligament.
They exhibit concentric appositional layers of
afibrillar and/or fibrillar cementum.
It is mostly found in aging persons or at the
43. Types
Free – with in PDL space
Attached- fused to cellular cementum
Interstitial –(totally incorporated in the cementum)
.
44. 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.
45. CEMENTOMA
It is also known as benign cemtoblastoma or
cemental dysplasia.
These are cemental masses situated at the
apex of the root which are slowly growing
odontogenic neoplasm and may
cause bone expansion.
47. ANKYLOSIS
Fusion of cementum & alveolar bone with
obliteration of periodontal ligament is termed
ankylosis.
48. CAUSES:
Faulty replantation & transplantation of teeth in
which periodontal ligament is damaged.
Embedded teeth.
Chronic periapical infection.
Trauma to deciduous teeth.
49. CLINICAL FEATURES:
Ankylosed teeth lack physiologic mobility of normal
teeth.
Ankylosed teeth have a special metallic percussion
sound & if ankylotic process continues, they will be
in infraocclusion.
RADIOGRAPHICALLY:
Resorption lacunae are filled with bone, and
the periodontal ligament space is missing.
50. 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.
51. TREATMENT:
No predictable treatment can be suggested.
Treatment modalities range from a conservative
approach such as restorative intervention to surgical
extraction of affected tooth.
If a primary tooth was ankylosed,
If the onset is early
Extraction is recommended with placement of a
space maintainer.
If the onset is late
Can build up with composite to occlusal plan.
52. If a permanent tooth is ankylosed,
Build up with restorative material to maintain
contacts.
Opposing teeth should never be allowed to supra
eruption.
If ankylosis occurs in multiple teeth, a segmental
alveolar bone osteotomy and bone graft may be
needed.
53. CHANGES IN ANKYLOSED
TEETH
As the periodontal ligament is replaced with
bone in ankylosed teeth proprioception is lost
because pressure receptors in the periodontal
ligament 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.
54. CEMENTUM RESORPTION
- Trauma from occlusion
- Orthodontic movement
- pressure from malaligned
erupting teeth
- cyst ,tumor, embedded teeth
-replanted and transplanted teeth
- periapical and periodontal disease
LOCAL
FACTORS
55. - calcium deficiency
- hypothyroidism
-Paget’s disease
- deficiency of vitamin A & D
-hereditary fibrous osteodystrophy
SYSTEMIC
FACTORS
56. CEMENTUM REPAIR
It requires the presence of viable connective
tissue.
If epithelium proliferates into an area of
resorption, repair will not take place.
It can occur in devitalized as well as vital teeth.
57. Anatomic Repair:
The root outline is re-established as it was
before cemental resorption. Generally occurs
when the degree of destruction is low.
Functional Repair :
In the case of large cemental resorption or
destruction, repair does not re-establish the
same anatomic contour as before, because
only thin layers of acellular and cellular
cementum are deposited over the concavity
created by cemental resorption.
58. To maintain the width of periodontal ligament,
the adjacent alveolar bone grows and takes the
shape of defect following the root surface. This
is done to improve the function of tooth, thus
called functional repair.
59. EXPOSURE OF CEMENTUM TO
ORAL ENVIRONMENT
Cementum becomes exposed to the oral
environment in cases of:
Gingival Recession
Loss of attachment in pocket formation
Bacterial invasion of cementum occurs
frequently in periodontal disease.
Cementum caries can develop.
