2. CEMENTUM: is a specialized hard layer of calcified
mesenchymal tissues which forms the outer covering of the
anatomical root.
Begins at cervical portion of the tooth at the cementoenamel
junction & continues to the apex.
3. Function
• Furnishes a medium for the attachment of
collagen fibers that bind the tooth to
surrounding structures.
• Serves as major reparative tissue for root
surface.
4. Distrbution
I. It varies in thickness at different levels of the root. It is
thickest at the root apex and in the interradicular areas
of multirooted teeth, and thinnest cervically.
II. The thickness cervically is 10-50μm, and apically, 50-
200μm. It is contiguous with the periodontal ligament on
its outer surface and is firmly adherent to dentine on its
deep surface.
III. As cementum is slowly formed throughout life, this
allows for continual reattachment of the periodontal
ligament fibers.
IV. It is deposited throughout life and there is always a thin
layer of uncalcified matrix on its surface.
5. Physical Characteristics
I. Hardness is less than that of dentin and bone.
II. Light yellow in color, It’s lighter in color than
dentin but more darker than enamel.
III. Can be distinguished from enamel by its lack of
luster & its darker hue.
IV. Permeable to a variety of materials, Its
permeability decreases with age.
V. Avascular receive nutrient from the surrounding
periodontal space and not innervated.
6. Chemical Composion
I. Contains 45% to 50% inorganic substances
mainly calicum, hydroxyapatite, phosphate &
fluride.
II. 50% to 55% organic material & water.
III. Organic portion consists primarily of type I
collagen & proteoglycans.
IV. Cementum has the highest fluoride content of
all the mineralized tissues.
7. Cementogenesis
Cementum develops from the activity of
esenchymal cells of dental follicle after
fragmentation of the epithelial root sheath.
After formation of dentin, loss of continuity
occurs in the epithelial root sheath.
This allows adjacent cells of the investing layer of
the dental follicle to come to lie on surface of root
dentin & these are induced to differentiate into
cementoblasts.
9. Cellular components of cementum
Cementocytes
I. Soon after Hertwig’s sheath breaks up, undifferentiated
mesenchymal cells from adjacent connective tissue of the
dental sac differentiate into cementoblasts.
II. The spaces that the cementocytes accupy in the tissue are
called lacunae, and the channels that their processes
extend along are the canaliculi, adjacent canaliculi are
often connected.
III. They are preferentially orientated towards the
periodontal ligament to get their chief source of
nutrition.
IV. Some unmineralized matrix may be seen in perilacuna
space.
10. Cementoblast
I. Line up along the cemental surface in the PDL which
responsible for replacement of cementum if tooth is
injured.
II. Synthesize collagen & proteoglycans which make up
the organic matrix of cementum.
III. Have numerous mitochondria, a well-formed golgi
apparatus, & large amounts of granular endoplasmic
reticulum.
14. Fibers
The fibrous matrix consist both:
Sharpey's fibres(Extrinsic fibers ): are the terminal
ends of principal fibres of the periodontal
ligament, that insert into the cementum and
into the periosteumof the alveolar bone,it’s
perpendicular or oblique to the root surface.
Intrinsic fibers: It’s non periodontal collagen
fibers made up by cementoblast and all of these
fibers run parallel to the DCJ.
16. Classification of cementum
Acellular cementum Cellular cementum
I. Covers the apical third and
interradicular.
II. Formed after the tooth reaches
the occlusal plane.
III. It contains embeded
cementocytes.
IV. Thickness is in the range of 100-
1000 μm
V. Lesser number of Sharpy’s
fibers.
VI. Main function is adaptation.
VII. Formed at faster rate.
VIII.Deposited over the acellular
cementum.
I. Covers the cervical third of the
root.
II. Formed before the tooth reaches
the occlusal plane.
III. Does not contain embedded
cementocytes.
IV. Thickness is in the range of 30-
230 μm
V. Abundance of sharpey’s fibers.
VI. Main function is anchorage.
VII.Formed at slow rate.
VIII.First layer of cementum.
19. Cementodentinal Junction
Smooth in permanent teeth, But Scalloped in
deciduous teeth.
Dentin is separated from cementum by a zone
known as the intermediate cementum layer.
This layer is predominantly seen in apical two-thirds
of roots of molars & premolars.
21. Cementoenamel Junction
In 60% of the teeth, cementumoverlaps the cervical
end of enamel for a short distance.
In 30% of all teeth, cementum meets the cervical end
of enamel in a relatively sharp line.
In 10% of the teeth, enamel & cementum do not meet.
24. Enamel pearls
Occur if epithelial sheath fails to be displaced from
the dentin surface, the IEE may become
differentiated into ameloblasts and produce an
enamel droplet (or pearl) on the root surface.
This usually occurs in close proximity to the
cervical region.
may become exposed and act like calculus to favor
plaque retention and promote periodontal disease.
26. Hypercementosis
Is an abnormal thickening of cementum.
May be diffuse or circumscribed.
May affect all teeth of the dentition, be confined to a single tooth, or
even affect only parts of one tooth.
If the overgrowth improves the functional qualities of the cementum,
it is termed cementum hypertrophy.
If the overgrowth occurs in non-functional teeth or if it is not
correlated with increased function, its termed cementum
hyperplasia.
Extensive hyperplasia of cementum is occasionally associated with
chronic periapical inflammation.
Hyperplasia of cementum in non-functioning teeth is characterized by
a reduction in the number of Sharpey’s fibers embedded in the root.
may complicate the extraction of affected teeth.
appear on radiograph as radiopaque mass at the root apex.
28. Cementicles
Small, globular masses of cementum.
found in approximately 35% of human roots.
They are not always attached to the cementumsurface
but may be located free in the periodontal ligament.
It may result from microtrauma & aging.
They are more common in the apical and middle third
of the root and in root furcation areas.
May interfere with periodontal treatment.
31. Enamel projections
Occur if amelogenesis is not turned off, continued
amelogenesis may produce enamel projections on
the root surface.
Most commonly extending into molar bifurcations.
May favor the development of periodontal disease in
affected bifurcations.
33. Cementum exposure
Gingival recession
Gum recession is not directly linked with age but
generally it is a more common condition in adults over
the age of 40.
Causes: poor plaque control, abrasion due to “hard”
tooth brushing habits, mouth trauma and occlusion.
problems associated: tooth sensitivity, cemental caries
risk, periodontal disease, esthetic problems.
Bone loss also occurs with gingival recession, giving less
support to the teeth.
35. Clinical Concederation
1. Anchoring function: it mediates the attachment
of the tooth to the gingival connective tissue, as
well as to the periodontal ligament and, hence, the
alveolar bone.
2. Protective function: as it is less susceptible
to resorption than bone.
This allows pressure induced movement of the tooth
through bone, as in orthodontics, while
minimizing resorptive damage to the tooth.
36. Causes Of Cemental Resorption
Trauma from Occlusion .
Deficiency of Ca .
Cyst & Tumors Deficiency of Vit. A & D.
Periapical Pathology .
Hypothyroidism .
Excessive orthodontic forces .
37. 3. Reparative function: New cementum formation
is a key process during therapeutic procedures
aimed at gaining new attachment, as it mediates
new attachment of the tooth to the periodontal
ligament and bone.
While it is possible for bone to fuse directly with
the dentin and cementum of the tooth through
ankylosis, this is considered an undesirable
process, as it results in progressive resorption of
the tooth structure because of ongoing
osteoclastic (odontoclastic) activity.
4. Regular Cementum deposition at the root apex,
helps to replenish the lost tooth height due to
occlusal wear.
38. Aging Of Cementum
Surface become rough and irrigular.
Cemental Resorption.
Permeability Decreases.
More Cemental deposition is greater in the apical
zone, which may lead to closure of the apical foramen.
The lacunae of cellular cementumappear empty (loss
of cementocytes).
