Definitions, Functions, Classification, Cementogenesis, Repair & Regeneration, Pathology Related to Cementum

1. CEMENTUM
Dr. Abhishek Shah
MDS Part-I

2. Periodontium
• The periodontium consists of those tissues
which surrounds , support the tooth and is
composed of:
1. Gingiva
2. Periodontal Ligament
3. Cementum
4. Alveolar bone

4. • Cementum is a calcified,
avascular mesenchymal
connective tissue that forms the
outer covering of anatomic root.
(Carranza 11th edition)
• First demonstrated in 1835 by
FRANKE & RASCHKOV, two
pupils of Purkinje.
• Cementum furnishes a medium
for the attachment of collagen
fibers that bind the tooth to
surrounding structures.

5. Acellular cementum (16-60 µm)
Cellular cementum (150-200 µm)
Physical Characteristics
2- Thickness
1-Color
Light yellow
Lighter in color than dentin
3- Permeability
Permeable from dentin and PDL sides.
Cellular C is more permeable than acellular C.

6. Chemical Composition
45-50 % Inorganic
substances
50-55% Organic
substances
consists of
calcium
phosphate in
the form of
hydroxy-apatite
crystals
collagen
fibers
embedded
in a ground
substance .
protein
Polysaccharides
Cementum contains the greatest amount of fluoride
in all mineralized tissues
By/ Dr. Hesham
Dameer

7. Functions of cementum :
1. Furnishes a medium for the incorporation of the principal
periodontal fibers,.
2. Serves as a reparative tissue in case of root fracture or
resorption .
3. Functional adaptation :
* When the superficial layer of cementum functionally
ages, a subsequent layer is deposited thus restoring the
integrity of the attachment apparatus .
* Another feature of functional adaptation is the
excessive formation of cementum on the apical root
surface to compensate for the occlusal and incisal wear
and restore the normal occlusion .

8. Classification
• Based on the location:-
1. Coronal cementum
2. Radicular cementum
• Based on the time of formation:-
1. Primary Cementum
2. Secondary Cementum
• Based on its cellularity:-
1. Cellular Cementum
2. Acellular Cementum

9. SHROEDER & PAGE
CLASSIFICATION 1986
1. Acellular Afibrillar Cementum
2. Acellular Extrinsic Fiber Cementum
3. Cellular Intrinsic Fiber Cementum
4. Cellular Mixed Stratified Cementum
5. Intermediate Cementum

11. 1.Acellular Afibrillar Cementum
 Mineralized Ground Substance.
 Connective tissue cells are responsible for this cementum
formation when they come in contact with the enamel.
(Schroeder HE,1986)
2.Acellular Extrinsic fiber Cementum
 Densely packed bundles of Sharpey’s fibers that are derived
from pdl.
 Coproduct of cementoblast and fibroblast.
 Cementoblast producing AEFC begin their cell differentiation
in closest proximity to the advancing root edge.

12.  The AEFC matrix consists of a dense fringe of
short collagenous fibers that are implanted into
the dentinal matrix and oriented about
perpendicularly to the root surface.
 The outwardly progressing mineralization front in
dentin does not reach the future CDJ until the
collagenous interdigitation of the two fibril is
established.

13.  Due to posteruptive tooth movements, changes
can occur in the direction of the Sharpey's fibers.
 These changes are accentuated by individual
AEFC layers interfaced by growth lines, also
known as resting or incremental lines.

14. 3. Cellular Intrinsic Fiber Cementum
• Initially deposited on root surface areas where no
AEFC has been laid down on the dentin.
• Functional stimuli, tooth contact and mastication
force are thought to be responsible for the onset
and appositional growth of CIFC.
• Fills resorption lacunae
• Adaptation that brings and maintain the tooth in its
proper position

15. 4. Cellular Mixed Stratified Cementum
• CIFC may overgrow layers of AEFC and in turn,
AEFC can overlay CIFC. The so formed mingled
cementum is called CMSC.
5. Intermediate Cementum
• Contains cellular remnants of HERS embedded in
calcified ground substance.
• Layer appears structureless and irregular
branching spaces known as Hyaline Layer Of
Hopwell Smith

16. Cementogenesis

17. • It takes place in two phases:
• Matrix formation
• Mineralization
• There are 3 cell types responsible for the cementogenesis:
• Cementoblasts
• Cementocytes
• Fibroblasts
• All of these cells are derived from the ectomesenchymal
cells.
By/ Dr. Hesham
Dameer

18. Cementoblasts Cementocytes

19. Enamel organ has reached its final size
Inner and outer enamel epithelium proliferate to
form HERS
Continuous cell mitotic activity at apical
termination of HERS
Coronoapical growth of double layer sheath
Most apical portion{diaphragm), separates the
dental papila from dental follicle
Inner and outer cell layers of HERS are
surrounded by basement membrane
DENTI
N
Epithelial Cell Rests of
Malassez (ERM)
Cementoblasts
Osteoblasts
Odontoblasts
Pulp
Follicle cells
Alveolar
bone
Hertwig’s epithelial
root sheath

20. Cells from dental papilla in the radicular pulp differentiate into
odontoblsts and forms radicular mantle dentin
HERS fragments and forms a network
Network enables mesenchymal cells to pass between cells of root
sheath
These mesenchymal cells are cementoblasts
Cementoblasts increase in size and develop all cytoplasmic
organelles

21. Mineralization
• Mineralization begins in the depth of precementum.
• Fine hydroxyapatite crystals are deposited, first between and
then within the collagen fibrils by a process that is identical to
the mineralization of bone tissue.
• The width of the precementum layer is about 3-5 um.
• Zander HA et al, 1958 concluded that the mean,linear rate of
cementum deposition on single-rooted teeth is about 3 um per
year.

22. Cementoenamel Junction

23. The terminal apical area of
cementum where it joins
the internal root dentin is
called cementodentinal
junction.
Width of CDJ is 2 to 3 μm and
remains relatively stable
( Stein Tj et al, 1990)
Cementodentinal junction

24. Resorption and Repair
• Permanent teeth do not undergo physiologic resorption.
• The cementum is subject to resorptive changes that may be of
microscopic proportion, or sufficiently extensive to present a
radiographically detectable alteration in the root contour.
• Microscopic cementum resorption is extremely common; in
one study it occurred in 236 of 261 teeth (90.5%). (Henry
JL,1951)

25. Causes :-
Local conditions:-
 Trauma from occlusion
 Orthodontic movement
 Cysts, and tumors; teeth without functional
antagonists;
 Embedded teeth; replanted and transplanted
teeth;
 Periapical disease; and periodontal disease.
Systemic conditions:-
 calcium deficiency,
 hypothyroidism,
 Paget’s disease.

26.  Microscopically as baylike concavities in the root surface.
 Cementum resorption is not necessarily continuous and may
alternate with periods of repair and the deposition of new
cementum.( reversal line )
 Cementum repair requires the presence of viable connective
tissue. If epithelium proliferates into an area of resorption, repair
will not take place.

27. Developmental
Anomalies associated
with Cementogenesis

28. Cementicles
• Are small, globular masses of
cementum
• May be attached to the cementum
surface or may be located free in
periodontal ligament.
• These may result from microtrauma,
when extra stress on sharpeys fibers
causes a tear in the cementum.

29. Periodontal ligament
Cementum
Bone
Free Cementicles

30. Enamel Pearls
If some HERS cells remain attached to
forming root surface, they can produce
focaldeposits of enamel like structures
called ENAMEL PEARLS.
• Clinical significance :-
 They are plaque retentive structures.
 Promote periodontal disease.
 They look similar to calculus, but
cannot be scaled off.
 Only grinding will help in elimination.

31. Clinical Significance and
Abnormalities of
Cementum

32. Hypercementosis
(cemental hyperplasia)
 Prominent thickening of the cementum.
 An age-related phenomenon.
 It may be localized to one tooth or affect the entire
dentition.

33. Appearance: -
 Generalised thickening of
cementum, with nodular enlargement of
the apical third of the root .
 Spike like excrescenses (cemental
spikes) created by either the coalescence
of cementicles or the calcification of the
periodontal fibres at the site of insertion
into the cementum (Lester KS,1969)

34. ETIOLOGY :-
 The spikelike type of hypercementosis excessive tension from
orthodontic appliances or occlusal forces.
 In teeth without antagonists  effort to keep pace with excessive
tooth eruption.
 In teeth withlow-grade periapical irritation for the destroyed
fibrous attachment to the tooth.
Hypercementosis of the entire dentition may occur in patients with
Paget’s disease. (Rushton MA,1938)

35. • TREATMENT:-
 It could pose a problem if an affected tooth requires
extraction.
 In multirooted tooth, sectioning of the tooth may be required
before extraction (Basdra EK,1997)

36. Cemental Hypoplasia
• Absence or paucity of cellular cementum.
• Hypophosphatasia
o Error of metabolism. Deficiency of enzyme alkaline
phosphatase in serum or tissues.
oLoosening and premature exfoliation of deciduous
teeth, mainly anteriors.
o Exfoliated teeth microscopically show complete
absence of cementum or isolated areas of
abnormally formed cementum.

37. Ankylosis
 Fusion of cementum and alveolar bone and
obliteration of the periodontal ligament is called
ankylosis.
 Results in resorption of root and its replacement by
bone tissue.
• Ankylosis can also occur after:
1. Chronic periapical infection
2. Tooth reimplantation
3. Occlusal trauma
4. Around embedded teeth.
5. More common in primary dentition

38. Clinically:-
 Lack of
physiologic
mobility.
 Proprioception is
lost.
 Special metallic
percussion sound.
 Infraocclusion.
Radiographically:
 Resorption
lacunae are
filled with bone.
 Periodontal
ligament space
is missing.
Treatment:-
 No predictable
treatment can be
suggested.
Treatment
modalities range
from a conservative
approach to
surgical extraction
of affected tooth.
Characteristics

39. Exposure of Cementum
1. Bacterial Contamination
2. Hypermineralization

40. • Destruction of collagen fibers
• Collagen remnants of sharpey’s fibers undergo
degeneration
• Creating Environment for bacterial penetration
• It can also absorb toxins generated by plaque blacteria
• Fragmentation and breakdown of cementum
• Structural Damage

41. Conclusion
• Cementum forms a functional unit which is designed to
maintain tooth support, integrity, and protection.
• Minor, non-pathological resorption defects on the root
surface are generally reversible and heal by reparative
cementum formation.
• Irreversible damage may occur when the cementum is
exposed to the environment of a pocket or oral cavity.