2. Schema
• Introduction.
• Development of Cementum (Cementogenesis).
• Physical Characteristics.
• Composition.
• Microscopic Structure.
• Types of junctions & its clinical significance.
• Age Changes.
• Changes in Cementum during Pocket Formation.
• Local Conditions Leading to Changes in the Cementum.
• Systemic Conditions Leading to Changes in the Cementum.
• Neoplasms & Cemental Aberrations.
• Changes in Cementum during Different PDL. Therapies.
• Current Concepts.
• Conclusion.
3. Introduction:
Cementum is a
highly specialized
form of
mesenchymal
connective tissue,
which is hard,
avascular & forms
the outer covering
of the anatomic
roots of teeth.
First described in
1835, it has till
recently, remained
a poorly defined
tissue at the cellular
& molecular level.
It is unique in that
it is avascular,
devoid of
innervation, has no
direct blood supply
& lymph drainage.
4. The aim of this presentation is to
provide a comprehensive insight
into this unique tissue.
7. Development of Cementum
(Cementogenesis)…..
Formation of Cementum can be subdivided into:-
•where the Cementum is formed
during root development.
Pre - functional
development
stage
• which takes place when the
tooth is about to reach the
occlusal level & continues
throughout life.
Functional
development
stage
9. Pre – Functional Stage…..
Cementum formation
in developing teeth is
preceded by the
deposition of dentin
along the inner aspect
of Hertwig’s Epithelial
Root Sheath (HERS).
Once the 1st layer of
radicular mantle dentin has
been laid down by maturing
odontoblasts & before
mineralization of dentin
reaches the inner epithelial
cells, HERS becomes
fragmented.
Cells from the dental
follicle then penetrate
the HERS & occupy
the area next to the
predentin.
This direct contact of dentin
with the connective tissue of
the dental follicle, stimulates
the undifferentiated ecto -
mesenchymal cells to
differentiate into
cementoblasts, which begin to
produce collagen fibers
The first Cementum
deposited on the
superficial layer of mantle
dentin(hyaline
layer)contains enamel
matrix proteins.
10. Pre – Cementum
(Cementoid)…
The outermost layer of cemental matrix
which persists for life of the tooth.
Unmineralized & begins initially at the
CEJ.
Located between the calcified layer &
cementogenic /cementoblastic layer.
3-5µm thick in width; about a micron
at the apex.
Produces a compatible environment
for cementoblasts
Prevents cemental Resorption.
Attaches tooth to the surrounding
bone.
11. Mineralization…
Begins in the depth
of the pre -
cementum.
Fine hydroxyapatite
crystals deposited
initially between &
later on within the
collagen fibrils, with
the crystals
generally directed
parallel to the
direction of the
collagen fibrils.
Although the
additional cementum
is laid down
throughout life, the
mineral content of
this tissue once
formed, does not
seem to change
significantly with
age.
12. Key Proteins Proposed to Regulate
Cementogenesis…..
Functions related to
Cementogenesis :-
• Promotes cell differentiation &
subsequently cementogenesis
during development &
regeneration.
• PDGF alone / with IGF
promotes cementum formation
by altering cell cycle activities.
• Promotes cell proliferation,
migration & angiogenesis - key
events for the formation &
regeneration of periodontal
tissues.
Proteins / factors
• Growth factors :-
TGF- β super family.
PDGF & IGF.
FbGF .
13. Cont…..
• Adhesion molecules:-
Bone sialoprotein.
Osteopontin.
• Epithelial / Enamel like
factors :-
– (PTH related protein /
EMD).
Promotes adhesion of
selected cells to forming
root & aids in
mineralization.
Regulates events of crystal
growth.
Epithelial - mesenchymal
interaction promoting
follicle cells along
cementoblast pathway, PDL
repair & regeneration.
14. Cont…..
• Collagens:-
• Gla proteins:-
Matrix Gla proteins.
Bone Gla protein.
Collagens I & III play a key role in
regulating periodontal tissues during
repair & regeneration.
Collagen XII - assists in maintaining
PDL space versus continuous
formation of cementum.
Play a significant role in preventing
ectopic calcification.
Marker for cells associated with
mineralization(osteoblasts,
fibroblasts & cementoblasts).
15. Cont…..
Transcription factors :-
Other factors :-
Alkaline phosphatase.
Proteoglycans.
MMPs.
CbfaI & Osterix are the
master switches for
differentiation of
osteoblasts.
Formation of
mineralized tissues.
Promoting / inhibiting
differentiation of cells of
the periodontium.
16. Physical Characteristics of
Cementum…..
• Highly calcified connective tissue covering the
surface of the teeth from the CEJ to the apex &
also lines apex of the root canal.
• Site through which the connective tissue
apparatus of the PDL. ligament fibers are
inserted into the tooth.
17. Cont…..
• Hardness of the fully mineralized cementum is
< that of dentin.
• Light yellow in color & can be distinguished
from enamel by its lack of lusture & darker
hue; but lighter than dentin.
18. Cont….
• Cementum formation is most rapid in the apical
region, where it compensates for tooth eruption,
which itself compensates for attrition.
• Permeability:- both Cellular & Acellular
Cementum are permeable to a variety of
materials, with that of Cellular being > Acellular
Cementum.
19. Cont….
• In the Cellular Cementum, the canaliculi in
some areas are contiguous with the dentinal
tubules.
• Permeability of cementum ↓ces with age.
- ( Blayney, J. R.et al., 1941).
20. Composition of Cementum….
• Biochemical studies have shown that the composition
of cementum is similar to that of bone.
• On a dry weight basis, cementum has :-
Organic substances & water :- 50 - 55%.
Type I collagen (90%) of the matrix.
Protein polysaccharides (proteoglycans).
Glycoproteins & phosphoproteins.
Inorganic substances & water :- 45 - 50%.
21. Organic content……
Primarily consists of :-
• Type I collagen which is known to promote
cell attachment & serves as a critical molecule
for maintaining the integrity of both soft &
hard connective tissue during development as
well as repair.
• Type III collagen(<5%) :- found in high conc.
during development, repair & regeneration.
22. Cont…..
• Type XII collagen fibrils binding to type I
collagen & also to non-collagenous proteins.
• Also, trace amounts of Type V, VI & XIV
found in mature organic matrix derived from
Sharpey’s fibers & embedded at right angles /
obliquely into the root surface (extrinsic
fibers)- responsible for root anchorage &
produced by fibroblasts of PDL.
23. Cont….
• In contrast, those derived from cementoblasts,
run parallel to the root surface & at right
angles to the extrinsic fibers & called
‘Intrinsic fibers’.
24. Non – Collagenous Proteins…..
Rich in glycoproteins, phosphoproteins & a variety of
proteins like those found in bone – BSP, Osteopontin,
Osteonectin, Osteocalcin, Proteolipids, Dentin
matrix protein – 1 & several growth factors including
IGF & Cementum Attachment / Adhesion Molecule.
BSP & Osteopontin are predominant non –
collagenous glycoproteins which bind tightly to the
collagen matrix & have cell attachment properties,
taking part in the mineralization process during early
tooth development & contribute to cementoblast
progenitor cells.
25. Cont….
2 other glycoproteins – fibronectin & tenascin
are widely distributed, binding cells to the
components of the ECM.
Other multifunctional proteins such as laminin &
fibronectin act as chemoattractants in addition to
aiding adhesion.
Together with proteins like tenascin & BSP,
osteopontin & osteocalcin appear to be involved
in the mineralization process.
26. Cont….
Some cementum specific proteins are also present
such as CAP (Parker, T., et al, 1996) as a mitogenic
factor (Narayan, S., et al, 1991) CEM-1 (Slavkin H.
C., et al, 1989).
Cementoblasts & cementocytes produce high levels of
the GLUT-1–monosaccharide transporter, which may
play a role in cementogenesis( biomarker to
differentiate between cementoblastic & osteoblastic
lineage).-Koike, H. et al., (2005); Somerman, et al.,
(1987).
27. Cont….
Enamel related proteins have also been detected
in cementum.
Biochemical analysis have revealed chondroitin 4
– sulphate, chondroitin-6-sulphate, hyaluronic
acid, dermatan sulphate, in cementum.
Enzyme alkaline phosphate is thought to
participate in cementum mineralization .
- Beensten, (1989) .
28. Inorganic Content of
Cementum…
INORGANIC
MATERIAL (45-50%):
• Cementum is less mineralized than root dentin.
• Acellular extrinsic fiber cementum is comparatively more
mineralized because of uncalcified spaces such as lacunae &
uncalcified core of Sharpey’s fibers. & also because it is
slowly formed which allows longer & direct contact with
tissue fluids.
HYDROXYAPATITE
CRYSTALS:
• Like in all other calcified tissues, the principle component is
hydroxyapatite crystals, which are aggregates of calcium &
phosphate salts derived from tissue fluids & are arranged
parallel to the long axis of the collagen fibrils.
- Selvig, (1969).
29. Cont…..
MAGNESIUM:-
It is present in concentrations varying
from 0.5-0.9%.
0.5% is seen at the surface while 0.9%
is seen at cemento-enamel junction.
An important aspect is that
magnesium is the first element to leach
out in early carious lesions but is not
significantly reabsorbed during
remineralization;
.
FLUORIDE:-
It is an important constituent of
cementum. Its concentration is
highest in cementum amongst
all calcified tissues. (0.9%.)
Fluoride level in acellular
cementum is > of
cellular cementum.
31. Microscopic Structure of Cementum
CEMENTOBLASTS
Origin :-
• Are cemento – progenitor cells
synthesising collagen & protein
polysaccharide (proteoglycans) which
make up the organic matrix of
cementum.
• Arise from the dental follicle proper
which is ectomesenchymal in origin
(Tencate, 1971) - a derivative of the
cranial neural crest.
• Recent ultra-structural studies &
immunohistochemical studies support
the hypothesis that the cementoblasts
originate from the cells of HERS when
they undergo an epithelial mesenchymal
transformation.
Differentiation:-
• The fibrogenic cells of the dental follicle
are either fibroblasts / mesenchymal cells.
• Tend to become differentiated into
cementoblasts as they invade, approach &
align themselves along the external border
of the dentin to form cementogenic layer.
• Form a single / multicellular layer.
• The components of multilayered cells are
more flattened than that of single cells
• Contain mitochondria, an extensive
network of surrounding well developed
Golgi system & ribosomes.
• These features of cementum are similar to
those of other collagen producing cells to
which they are derivatively related..
33. Cementocytes…..
The apical 1/2 or 1/3rdof the root is covered with
cellular cementum.
The number of cementocytes in the matrix is variable.
Cementum that is formed rapidly generally possesses
wider lamellae & more cementocytes.
In the apical 1/3rd,cementoblasts trapped in rapidly
calcifying cemental matrix, later, differentiate into
cementocytes.
34. Cont…..
• These locate in spaces termed lacunae & have
numerous cytoplasmic processes coursing in
canaliculi, that are preferentially directed
towards the periodontal ligament.
• This is how cementocytes derive their nutrition
from periodontal ligament & contribute to the
vitality of this mineralized tissue.
35. Cont…..
• While adjacent canaliculi of neighboring
cells communicate frequently, the
processes remain independent.
• Thus, the metabolites progress mostly by
diffusion through the canaliculi of
cellular cementum.
36. Cementoclasts:
• They are multinucleated giant cells, which are
indistinguishable from osteoclasts.
• Responsible for root resorption that leads to
primary teeth exfoliation & also in the permanent
dentition in mesial surfaces in compliance with
mesial migration & may occur due to occlusal
trauma & orthodontic therapy.
37. Types of
Cementum
Embryologically Primary & Secondary
According to location
on teeth ( Kronfield
1928).
- Radicular cementum- found on root
surfaces.
- Coronal Cementum to Cementum that
forms on the enamel covering the crown.
On the basis of
cellularity (Gottlieb
1942).
- Acellular / Primary Cementum.
- Cellular / Secondary Cementum.
Schroder(1986)
classified cementum x 5
subtypes based on
cellularity &
organisation of collagen
fibres into
- Acellular afibrillar cementum.
- Acelluar extrinsic fiber cementum.
- Acellular intrinsic fiber cementum.
- Cellular intrinsic fiber cementum.
- Cellular mixed stratified cementum
Based on the origin of
the collagen matrix
- Extrinsic.
- Intrinsic.
- Mixed.
Depending on the
location & patterning
- Intermediate.
- Mixed stratified cementum.
38. Acellular Cementum:
• Refers to cementum lacking embedded cells.
• First formed cementum, covers approximately
the cervical ⅓ or ½ of the root & does not
contain cells (i.e., cells that form it remain on
its surface).
39. Cont……
• Formed before tooth reaches the occlusal plane.
• Thickness ranges from 30 – 230µm.
- Schroeder, (1986).
• Sharpey’s fibers make up most of the structure of
acellular cementum, which has a principle role in
supporting the tooth.
40. Cont….
• Most fibers are inserted at angles into the root
surface, are completely calcified with mineral
crystals oriented parallel to the fibrils, except in a
10 – 50 µm wide zone near the CEJ, where they
are only partially calcified.
• Also contains intrinsic collagen fibrils that are
calcified and are irregularly arranged / parallel to
the surface.
- Schroder, (1980).
42. Cellular Cementum:
• Is formed after tooth reaches the occlusal
plane.
• Is more irregular & contain cells
(cementocytes) in individual spaces
(lacunae).
• Less calcified than acellular cementum.
43. Cont…..
• Sharpey’s fibers occupy a smaller portion
of cellular cementum & are separated by
other fibers that are arranged either
parallel to the root surface or at random.
• Thickness of cellular cementum is greater
than acellular.
44. Cont…..
• Both cellular & acellular cementum are
arranged in lamellae separated by incremental
lines, parallel to the long axis of the root.
• These lines represent rest periods in cementum
formation & are more mineralized than the
adjacent cementum (Romanos 1992) &
termed the ‘Incremental lines of Salter’.
46. Differences Between Acellular &
Cellular Cementum…..
Acellular
Cementum
Cellular
Cementum
Formation Forms before tooth reaches
occlusal plane
After tooth reaches occlusal
plane
Cells Does not contain any cells Contains cementocytes
Location Coronal portion of root Apical portion of root
Rate of
formation
Slow Rapid
Incremental
lines
More Sparse
47. Cont…..
Acellular
Cementum
Cellular
Cementum
Function Forms after regenerative
periodontal surgical procedure
Contributes to the
length of the root during
growth
Calcification More calcified Less calcified
Sharpey’s fibers More Less
Regularity of
fibers
Regular Irregular
Thickness 20 – 50µm near the cervical
region &150 – 200µm near the
apex.
Thickness of 1 – several
mm.
48. Acellular Afibrillar Cementum
(AFC):
• Contains neither cells, nor extrinsic / intrinsic
fibers, apart from a mineralized ground substance.
• It is a product of cementoblasts, found deposited
on the enamel over small areas of the dental
crown just coronal to the CEJ.
• Thickness is about 1 - 15 µm.
49. Acellular Extrinsic Fiber Cementum
(AEFC):-
Composed almost entirely of densely packed
bundle of Sharpey's fiber and no cells.
• A product of fibroblasts and cementoblasts,
• found on the cervical ⅓ of roots, but may
extend further apically..
• Cementoblasts that produce AEFC
differentiate in close proximity to the
advancing root edge.
•
50. Cont….
• Thickness is between about 30 - 230 µm &
continues to grow in thickness (@ 1.5 - 3 µm /
year) as long as the adjacent periodontal
ligament remains undisturbed.
51. Cont…..
• During root development, the first formed
cementoblasts align along the newly formed,
but not yet mineralized, mantle dentin surface
& exhibit fibroblastic characteristics.
• Deposit collagen fibrils within it so that dentin
& cementum fibers intermingle.
52. Cont…..
• Initially AEFC consists of mineralized layer
with a short fringe of collagen fibers implanted
perpendicular to the root surface.
• Cementoblasts then migrate away from the
surface but continue to deposit collagen so that
a fine fiber bundle lengthens & thickens.
53. Cont…..
• These cells also secrete non – collagenous matrix
proteins that fill in the spaces between the collagen
fibers.
• Although this cementum is classified as AEFC, its
initial part should be classified instead as having
intrinsic fibers, as the collagen matrix of the first
formed cementum results from cementum – associated
cells & is elaborated before the periodontal ligament
forms( local / intrinsic.)
54. Cont…
Only after the first 15 – 20 µm have formed, the
intrinsic fibrous fringe become connected to
the PDL. fiber bundles.
The overall degree of mineralization of this
cementum is about 45 – 60%.
AEFC has the potential to adapt to functionally
dictated alterations such as mesial tooth drift.
55. Cellular Mixed Stratified Cementum
(CMSC):
• Contains both collagen fibers & calcified
matrix.
• It is the co – product of cementoblasts &
fibroblasts and consists of both extrinsic
& intrinsic fibers.
56. Cont…..
• Appears primarily in the apical third of the roots
& in furcation areas.
• Consists of AEFC and CIFC that alternate &
appear to be deposited in irregular sequence upon
one another.
- Schroeder, (1993).
• Deposited @ 0.1 – 0.5 µm / year.
57. Cellular Intrinsic Fiber Cementum
(CIFC):
• Contains cells but no extrinsic (Sharpey's)
fibers.
• Once the tooth is in occlusion, a more rapidly
formed & less mineralized variety of
cementum, (CIFC) is deposited on
unmineralized dentin surface near the
advancing root edge.
58. Cont…..
• Formed by cementoblasts & fills resorption
lacunae (resorptive cementum.)
• Can easily repair a resorptive defect of the root
due to its capacity to grow faster than any
other form of cementum.
59. Acellular Intrinsic Fiber Cementum
(AIFC):
• An acellular variant of cellular intrinsic fiber
cementum that is also deposited during adaptive
responses to external forces (i.e.,) slow deposition
rate so that cells are not engulfed in their matrix &
that forms without leaving cells behind.
- Bosshardt & Schroder, (1990)
.
60. Cont….
• In the light microscope, CIFC is identified easily because of the
inclusion of cementocytes within lacunae with processes directed
towards the tooth surface, laminated structure & presence of
cementoid on its surface.
• Fine, densely packed intrinsic fibers running parallel to the root
surface & larger, haphazardly incorporated extrinsic fibers
running at right angles to the root surface.
• Cellular intrinsic fiber cementum is initially deposited on root
surface areas where no acellular extrinsic fiber cementum has
been laid down on the dentin (furcation and on the apical root
portions).
61. Thickness of cementum & its clinical
significance…..
• Cementum deposition is a continuous
process that proceeds at varying rates
throughout life.
• The thickness on the coronal ½ of the
root varies from 16 µm in the apical third
to furcations - 150µm – 200µm.
62. Cont….
• It is thicker on the distal surface than on the
mesial, consequent to functional stimulation
from mesial drift over time(Polson.A et al
1990).
• Is more rapid in the apical region where it
compensates for attrition (passive eruption).
• Between the ages of 11 & 70, the average
thickness ↑ 3 fold, with the greatest ↑ in the
apical area.
63. Functions of Cementum….
Anchorage:-
the primary
function is
the
formation
of a
medium for
the
attachment
of collagen
fibers that
bind the
tooth to the
alveolar
bone.
Apical
cementogen
esis
compensate
for the
attrition of
enamel,
thereby
maintaining
occlusal
functional
relationship
.
Assists in the
maintenance
of the width
of the
periodontal
ligament by
cementogenic
activity.
Provides for
fiber
reattachment
& relocation
consequent to
mesial
drifting of
teeth.
Serves as a
major
reparative
tissue foll.
root
surface
damages
such as
fracture &
resorption
by
formation
of new
cementum.
Protects
underlying
dentin.
65. CEMENTO – DENTINAL
JUNCTION:
• After differentiation, cementoblats extend
numerous tiny processes at the beginning of their
maturation on the root surface.
• They encounter numerous tiny cytoplasmic
processes in the loosely arranged but not yet
mineralized dentinal matrix, leading eventually to
an intimate interdigitation of the two different
fibril populations.
66. Cont……
• The mineralization in dentin does not reach the
future dentino – enamel junction until the dentinal
matrix is covered with the collagen fibrils
of Cementum.
• Recent studies by Inamoto, et al., have suggested
that mucopolysaccaharides might have an
important role in the formation of the CD
junction.
67. Relation of Cementum to Enamel at the Cemento
– Enamel Junction (CEJ) ‘OMG’ rule---
• In about 60% of the teeth
,cementum OVERLAPS enamel
(enamel degenerates for a short
distance at its cervical termination)
• In about 30% of the teeth,
cementum just MEETS enamel.
• In about 10% of the teeth ,there is a
small GAP, where cementum &
enamel fail to meet.
69. DEPOSITION…..
Cementum formation continues throughout life unless
disturbed by periapical / periodontal pathology.
More cementum is deposited apically than cervically.
Thicker layers may form in the root surface grooves & in
furcations.
In the cementum of impacted teeth, sharpey’s fibres may
be nearly completely absent & may be built up mainly of
intrinsic fibres arranged parallel to the root surface.
70. Cont……
Great variations in the width of incremental
layers indicates that the rate of formation
varies from time to time.
Non – functional & impacted teeth appear to
have thicker cementum than functional teeth.
71. Cont…….
The distribution of cementum on impacted
teeth indicates that occlusal forces are not
necessary to stimulate cementum deposition.
In the posterior teeth, cementum deposition is
thicker on the distal side than on the mesial,
indicating a relationship to mesial drift
- Polson, A. (1990).
73. Cont…..
The cementum of erupted as well as
unerrupted teeth is subject to resorption.
The resorptive changes may be of microscopic
proportion / sufficiently extensive to be visible
on a radiograph.
74. REPAIR:
• Cementum resorption is not necessarily
continuous & may alternate with periods of repair
& deposition of new cementum.
• Newly formed cementum is demarcated from the
root by a deeply staining irregular line termed the
Reversal line (contains a few collagen fibrils &
proteoglycans) & delineates the border of the
previous resorption.
75.
76. ANKYLOSIS:
• Is the fusion of the cementum & alveolar bone with
obliteration of PDL.
• Occurs in teeth with cemental resorption, which
suggests that it may represent a form of abnormal
repair.
• May develop after chronic periapical pathology, tooth
replantation, occlusal trauma & around embedded
teeth.
77. Cont…..
• Occurs most frequently in the primary
dentition ( McNamara ,et al., 2000).
• Results in resorption of root & its gradual
replacement by bone tissue. For this
reason reimplanted teeth that ankylose
will loose their roots after 4 – 5 years &
will be exfoliated.
78. Cont…..
• .Clinically, ankylosed teeth lack physiologic
mobility of normal teeth which is one of the
first diagnostic sign for ankylotic resorption.
These teeth usually have a special metallic
percussion sound & if the ankylotic process
continues, they will be in infra - occlusion.
• Proprioception, physiologic drifting, eruption
as well as ability of teeth & periodontium to
adapt to altered force levels or direction of
force is greatly reduced.
79. EXPOSURE TO ORAL
ENVIRONMENT:
• Cementum becomes exposed to oral environment
in gingival recession & as a result of loss of
attachment in pocket formation.
• Cementum is sufficiently permeable to be
penetrated by organic substances, inorganic ions
& bacteria, leading to hypersensitivity to thermal
changes / tactile stimulation, root caries, etc...
sometimes resulting in pulpal pathology.
80. Changes in the Periodontium During
Pocket Formation……….
• A Periodontal pocket is defined as a ‘pathologically deepened
gingival sulcus’.
• The root surface wall of the periodontal pocket often undergoes
various changes that are significant because they may perpetuate
the periodontal infections, cause pain & complicate the
periodontal treatment.
• The changes may be grouped as ‘structural, chemical /
cytotoxic’.
81. Structural Changes:
• Presence of pathologic granules, representing
areas of collagen degeneration / areas not fully
mineralized initially.
- Bass, (1951).
82. • Areas of Increased Mineralization: -
Selvig, (1966) as a result of exchange
on exposure to the oral cavity, of minerals &
organic component at the cementum saliva
interface.
• Areas of Demineralization:-
Exposure to oral fluids & bacterial
plaque results in proteolysis of the embedded
Sharpey’s fibres, leading to softening of the
cementum, which undergoes fragmentation &
cavitation (root caries) → Pulpal sensitivity /
severe pain.
83. Chemical Changes……
• Exposed cementum has an increased mineral
content (Selvig 1966)- Ca, Mg, P, F. & may be
resistant to decay.
84. Cytotoxic Changes:
• These include bacterial penetration into
cementum as deep as the CDJ.
• In addition, bacterial products such as
endotoxins are also found deep in the cemental
wall of the periodontal pocket.
86. Changes in Cementum in
TFO…..
• Cementum deposition continues after the
teeth have reached into contact with
their functional antagonists and
throughout life.
• No correlation has been established
between occlusal function and cementum
deposition.
87. Cementum Changes During
Orthodontic Movement:
• Orthodontic movements when in proper
magnitude do not affect the cementum because
cementum, with its slow metabolism is not
damaged by a pressure equal to that exerted on
bone.
• However, when the forces exceed, cemental
resorption occurs on the pressure side while
deposition takes place on the tension side.
88. Fracture of the Root:
• Cementum is repaired by deposition of new
cementum and requires the presence of new
viable connective tissue.
• If epithelium proliferates into that area, repair
will not take place.
• Cementum repair can occur in both vital as well
as non- vital teeth.
89. Cementum
Hypophosphatasia:
• Hypophosphatasia is caused by a mutation in
the tissue specific alkaline phosphatase
gene.→ Deficiency in alkaline phosphatase
characterized by premature loss of primary
teeth, & reduced cementum formation.
91. Cleidocranial Dysplasia:
• It is a developmental anomaly affecting mainly the
skeleton and teeth (affects the skull, clavicle and
dentition).
• A study showed a paucity or complete absence of
cementum due to defective formation of cellular
cementum on both erupted and unerupted
teeth.(Rushton, M.A1956).
• Prolonged retention of deciduous teeth, subsequent
delayed eruption of succedaneous teeth as well as
numerous unerupted supernumerary teeth.
92. Hypopituitarism:
• In this, there is reduced pituitary hormones
specially the growth hormone.
• Individuals with this condition show dwarfism but
have a relatively well proportioned body.
• Decreased cementum formation is associated with
hypopituitarism.
93. Papillon Lefevre Syndrome:
It is a familial, autosomal recessive
disease, characterized by aggressive
periodontitis with early loss of deciduous as
well as permanent teeth.
94. Cont…..
Hyperthyroidism :-
Shedding of deciduous teeth earlier than eruption of
permanent teeth is greatly accelerated.
Hypothyroidism :-
Eruption rate is delayed & deciduous teeth are retained
beyond their normal shedding time.
Down’s syndrome- generalised cementopathia.
95. Neoplasms of Cementum….
• Benign cementoblastoma is a true neoplasm of
functional cementoblasts that form large masses of
cementum like material on the root surface.
• The lesion normally occurs under the age of 25 yrs,
with no sex prediliction.
• Mandible 3 fold more commonly affected than
maxilla.
96. Cont…..
• Usually slow growing & asymptomatic.
• Radiographically, appears as a dense radio –
opaque mass often surrounded by a thin
radiolucent line.
• Treatment - Extraction of the tooth along with
complete removal of growth, failing which,
there’s a recurrence.
99. Cont……
• Occurs as a generalized thickening of cementum
with nodular enlargement of apical third of root /
as spike like excrescences created by either the
coalescence of cementicles that adhere to root /
the calcification of periodontal fibers at the site
of insertion into the cementum. ( Lester, 1969).
• If the over growth improves the functional
qualities of the cementum; it is termed as
‘cemental hypertrophy’.
100. Cont…...
• If the overgrowth occurs in non - functional
teeth / if it is not correlated with increased
function, it is termed ‘Hyperplasia’.
• In localized hypertrophy, a spur or prong like
extension of cementum may be formed- found
in teeth that are exposed to great stress.
101. Aberrations….
• Sometimes, embedded calcified round bodies are
found in localized areas of hyperplastic cementum.&
are designated excementosis, & develop around
degenerated epithelial rests.
• Etiology is varied & includes excessive tension from
orthodontic forces,excessive occlusal forces & in teeth
without functional antagonists, as an attempt to keep
pace with excessive tooth eruption.
102. Cont…..
• In low – grade periapical irritation from pulp
disease it compensates for the destroyed
fibrous attachment to tooth.
• Paget’s disease, Osteitis deformans
Hyperpituitarism. Gigantism & Acromegaly. –(
Sponge, 1979).
103. CEMENTICLES:
• Calcified bodies in the PDL. that are adherent to
or detached from the root surface & its diameter
rarely exceeds 0.2 mm.
• Develop from calcified epithelial rests, around
small spicules of cementum / alveolar bone
traumatically displaced into PDL., from calcified
Sharpey’s fibers and thrombosed vessels within
the PDL.
104. CEMENTOMA:
• These are masses of cementum generally
situated apical to teeth to which they may or
may not be attached.
• They are considered either odontogenic
neoplasms / developmental malformations.
• Occurs more frequently in females than males.
105. Cont…..
• Seen more commonly in mandible as
compared to maxilla and
• May be single / multiple.
• Radiographically, the lesion appears as a
discrete, dense, radio-opaque mass in which
isolated radiolucent markings may be seen.
106. CEMENTAL TEARS:
• Detachment of fragments of cementum from the root
surface is known as ‘Cemental tear’, which may be
complete or incomplete.
• Detached cementum may be reunited by new
cementum formation or may be completely resorbed /
undergo partial resorption followed by the addition of
new cementum & embedding of collagen fibers.
107. Changes in Cementum during
Different PDL. Therapy…
• Mechanical and chemical means have been
used to promote favorable root surface
characteristics.
• Regeneration, repair and new attachment are
the aspects of periodontal healing that have a
special bearing on the results obtainable by
treatment.
108. ROOT BIOMODIFIERS:
• It is well accepted that in order to improve
periodontal healing, root planing / root
conditioning is a necessary antecedent to
mesenchymal cell migration & attachment onto
the exposed root surface.
• Root conditioning can be done by using acids
(citric acid, HCL, Lactic acid & EDTA),
Fibronectin & EMP.
109. Acid Demineralization:
• The teeth treated with acid demineralization heal
by connective tissue reattachment, with evidence
of accelerated cementogenesis.
• It removes the dentinal smear layer, enlarges the
opening of dentinal tubules & exposes the
collagen dentinal matrix, which provides a
substrate for fibrin linkage & can support
attachment & migration.
110. Changes During Therapy…….
ROOT PLANING:-
• In periodontitis, various root surface changes
occur due to bacterial deposits on, calculus and
/ or any other plaque retentive factors.
• Therefore, to remove these from the root
surface, the basic treatment modality in any
type of periodontitis is ‘Root planing’.
111. Cont….
• Thorough root planing of diseased root
surfaces, arrests disease progression & aids in
the removal of the nidus of infection.
• According to Jan Lindhe & H. Rylander,
‘Root Planing’ removes the softened
cementum, resulting in a hard & smooth root
surface.
112. Changes following Root
Planing…..
• Ruben, et al., (1975) suggested that the
therapeutically debrided & planed root surface
initially undergoes superficial demineralization &
resorption of the cemental matrix that involves
embedded collagens & reticular fibers
• This is because of the acidic & enzymatic
activity of post surgical inflammation, occurring
48 hrs after surgery.( Frank & Cimasoni)
113. Cont….
• It is necessary to prepare the root surface to the extent
that mineralized dentin /cementum is exposed at the
time of surgery.
• Superficial demineralization subsequently
remineralizes from the adjacent tissue fluid 2 – 3 days
after surgery.
• Once the layer gets mineralized, cementogenesis takes
place.
114. How does Cementum hold on to
Dentin???????
• Attachment mechanism of cementum to dentin is both of
biological interest & of clinical relevance, since
pathological alteration & clinical intervention may influence
the nature of exposed root surface.
• Hence, the quality of the new attachment that forms
depends on the repair cementum that is deposited.
• The mechanism of binding together of these hard tissues is
essentially same for AEFC & CIFC.
115. Cont….
Repaired cementum adheres very well to the root surface if a resorptive phase
precedes new matrix deposition, implying that odontoblasts favorably
precondition the root surface.(Bosshardt DD 2005
From a biochemical perspective, this arrangement appears optimal
for a strong union between dentin & cementum
Resulting in an amalgamated mass of minerals
Then it spreads through the surface layer of dentin, across the
dentin – cementum junction & into cementum
Mineralization of mantle dentin starts internally & does not reach the surface
until collagen fibrils of dentin & cementum blend together
117. Changes / Healing after
periodontal therapy:-
• The process of PDL. tissue regeneration starts at the moment of
tissue damage, by GF & cytokines released by damaged CT &
inflammatory cells.
• Regeneration, repair & new attachment are aspects of periodontal
healing that have a special bearing on the results obtainable by
treatment.
• A critical step in periodontal regeneration therapy is to alter the
periodontitis affected root surface to make it a conducive substrate
to support & enhance migration, attachment & proliferation &
proper phenotypic expression of periodontal connective tissue
progenitor cells.
118. In Regeneration…….
• It is the growth & differentiation of new cells
& intercellular substances to form new tissues
/ parts.
• Takes place by growth from the same type of
tissue that has been destroyed / from its
precursors.
119. Cont….
• Bone & cementum are not replaced by existing
bone & cementum, but by connective tissue
which is the precursor of both.
• An undifferentiated connective tissue cell
develops into osteoblasts & cementoblasts,
which later forms bone & cementum.
120. Cont…..
• Continuous deposition of cementum takes
place by removing bacterial plaque & calculus
& creating conditions that enhances its new
formation.
• Periodontal treatment removes the obstacles to
regeneration & enables the patient to benefit
from the inherent regenerative capacity of the
tissues.
121. Cont…….
• Restoration of the destroyed periodontium
involves mobilization of epithelial &
connective tissue cells into the damaged
areas & increased local mitotic divisions
to provide sufficient number of cells.
Repair :-
• New attachment is the embedding of new
periodontal ligament fibers into new
cementum & the attachment of the
gingival epithelium to a tooth surface
previously denuded by disease.
New
attachment:-
122. GTR
• GTR consists of placing barriers of different types to
cover the bone & PDL., thus temporarily separating
them from the gingival epithelium.
• Excluding the gingival epithelium & connective tissue
from root surface during the post surgical healing
phase not only prevents epithelial migration into the
wound, but also favors repopulation of the area by
cells from the PDL. & bone.
123. (Nyman et al 1982)…..
• Using millipore membranes, introduced the
concept of a membrane barrier, which excludes
the apical migration of gingival epithelial cells
and provides an isolated space for the inwards
migration of periodontal ligament cells,
osteoblasts and cementoblasts.
124. Cont…..
Under the guided conditions used, cementogenesis
follows two distinct patterns:-
In the first pattern, a
fringe(formed by cells
resembling cementoblasts) of
collagen fibrils oriented more
or less perpendicular to the pre-
existing root surface is laid
down initially.
In contrast, the 2nd pattern of
regeneration involves the
accumulation of sheets of collagen
fibrils arranged largely parallel to the
root surface, running both axially &
circularly.
This matrix apparently is produced by
cementoblasts like cells that
occasionally are embedded in
their products as cementocytes.
125. Cont…..
• Both the types of regenerative cementum seem to merely
adhere to the supporting hard tissues through an
intervening thin layer of afibrillar, electron dense material
& lack an attachment to dentin- characterized by inter –
digitations of collagen fibrils as seen along natural CDJ.
• It has also been questioned whether guided tissue
regeneration produces true cementum regeneration or
only cemental repair.
• The newly formed cementum has been characterized as
a cellular cementum that is usually poorly attached to
the dentin surface .
(Kostopoulos et al 2004).
126. Cont….
• It is suggested that periodontal healing with guided
tissue regeneration therapy occurs in two stages:
•comprises an initial healing phase with the formation
of a blood clot, transient root resorption /
demineralization, deposition of acellular cementum on
the root surface and formation of connective tissue.
The
1st
Phase
• comprises a remodeling process, which will result in
a regenerated cementum similar to pristine
cementum as maturation proceeds over time.
- Graziani, F. et al., (2005).
The
2nd
Phase
127. Wound Healing….
• Viable cementoblasts and / or periodontal ligament
cells near the cementum appear to play a critical role
in the regeneration of the tooth attachment apparatus.
• If an avulsed tooth is replanted into the tooth socket
shortly after the avulsion (or the tooth is stored in the
conditions that allow for cell survival), cementum -
mediated attachment is efficiently re-established.
128. Cont…..
• In contrast, if the avulsed tooth is replanted
without viable cells present, the healing
process is frequently impaired, and severe
complications (i.e., ankylosis, root resorption)
are more likely to develop.
- Boyd, et al., (2000).
129. Cont…..
• This indicates that viable cementoblasts & / or
intact molecules associated with them, in
addition to cementum matrix are likely to be
actively involved in recruiting cells that next
differentiate into cementoblasts and form new
cementum that is critical for re – establishing
structurally & functionally sound attachment.
130. Do enamel associated proteins generate
cementum????
• A multitude of studies(Lindskog-1982;Slavkin-
1989)—in vivo ,in vitro & clinical studies have
generated the foll .information-
• ↑ migration of PDL cells
• ↑ cell attachment
• ↑ cell proliferation
• Stimulate matrix production.
• Inhibit the division of epi.cells.
131. Some Important Molecules Identified in
Cementum and Their Activity
Molecule: Biological Activity:
IGF-1. Proliferation, differentiation, matrix synthesis
FGF. Proliferation, differentiation, matrix synthesis,
angiogenesis.
PDGF. Proliferation, differentiation, matrix synthesis.
TGF-ß. Matrix synthesis, angiogenesis, chemotaxis.
BMPs. Matrix synthesis, differentiation, bone formation.
EGF. Proliferation, differentiation
CGF. Proliferation, differentiation.
134. Summary…..
• Cementum is a part of periodontal attachment
apparatus, & by virtue of its structural dynamic
qualities, provides tooth attachment and
maintains occlusal relationship.
• These multiple functions are fulfilled by the
biological activity and reactivity of cementoblasts,
which deposit two collagen containing varieties of
cementum with completely different properties.
135. Cont…..
Unless disturbed, cementum covering of the root
↑ in thickness throughout life, faster apically than
cervically.
Chemical composition is almost similar to bone.
The dynamic features of cementum are
particularly highlighted by its repair potential.
136. Cont…..
Minor, non - pathological resorption defects on
the root surface are generally reversible and heal
by reparative cementum formation.
In diseased periodontium, cementum may
undergo alterations in structure as well as in the
composition of its organic and inorganic
components consequential to pathological
changes.
137. Cont…..
The discovery of a variety of non –
collagenous proteins in cementum has opened
new vistas for research - the application of
cementum derived growth factor /
attachment factors may result in accelerated
wound healing & in controlled neo – cemento
genesis following periodontal regeneration
therapy.
138. So, What’s new ???
• Numerous studies support the possibility that cementum
derived attachment proteins,(a 56k Da protein)along with
their receptors,are expressed in a unique fashion during
cementogenesis,predicting that their precisely timed
expression is critical to cementum formation.(Sommerman
et al)
• Spatial & temporal localisation of these proteins, pre & post
cementogenesis will provide pertinent information
necessary for establishing the function of these proteins
during root development , permitting new & improved
periodontal treatment that could greatly diminish the
effects of periodontal disease.(A.Narayanan .S & Pitaru)
139. contd
• Human cementoblastoma derived protein,named
Cementum Protein-1 (CEMP 1)-expressed by
cementoblasts & progenitor cells localised in the
periodontal ligament, may play a crucial role as a
local regulator of cementoblast differentiation and
cemental matrix mineralisation.(Bruno-Carmona
Rodriguez et al )
140. Conclusion…..
• In the light of emerging evidence, we can hypothesize that the
local environment of the cemental matrix plays a pivotal role in
maintaining the homeostasis of the periodontium.
• The structural integrity & unique biochemical composition of
the cemental matrix are severely compromised in periodontal
disease & the provisional matrix generated during periodontal
healing is different from cementum.
• Rapid strides made in basic science research indicate that the
ultimate goal of true periodontal regeneration may become
possible.
141. References:
1. Biology of the Periodontium - A. H. Melcher & W.
H. Bowen.
2. Biological Structure of the Normal & Diseased
Periodontium - Periodontology 2000,vol 13 -1997.
3. Oral Cells and Tissues – P. R. Garant
4. Oral Anatomy, Embroyology & Histology- B.K.B.
Berkovitz, G. R. Holland, B.J. Moxham.
5. Cementum &Periodontal Wound Healing and
Regeneration – Wojciech.J.Grzesik, A .S.narayanan
Critical reviews of oral biology and medicine
2002;13(6) 474-84.
142. MCQ’s…..
Most common presentation of CEJ is:
– Enamel overlaps cementum.
– Cementum overlaps enamel
– Butt-joint.
Failing to meet each other.
Adhesion molecule present in cementum.:
- Cementum attachment protein.
- Vascular adhesion molecule.
- Insulin growth factor.
- None of the above.
143. Cont….
Which of the following is more mineralized:
- Acellular extrinsic fiber cementum.
- Cellular mixed stratified cementum.
- Cellular intrinsic fiber cementum.
• -Intermediate cementum.
• Cementum that usually fills resorption lacunae
lacunae
- Cellular intrinsic fiber cementum
- Intermediate cementum
- Acellular extrinsic fiber cementum
- None of the above
