Outermost layer covering of the tooth root

1. CEMENTUM
Dr Gauri Kapila
Department of Periodontology and
Oral Implantology

2. Contents
 Introduction
 Development of cementum
 Molecular factors affecting
cementogenesis
 Physical properties
 Chemical Composition
 Histology of cementum
 Classification
 Cementodentinal junction
 Cementoenamel junction
 Functions
 Cementum resorption and
repair
 Effects of ageing on
cementum
 Cementum in oral
environment
 Role of cementum in
periodontal disease
 Changes in cementum
 Effectiveness of root planing
 Developmental anomalies
 Conclusion
 References

3. INTRODUCTION
DEFINITION- calcified avascular mesenchymal tissue that forms the outer
covering of the anatomic roots
EXTENT- begins at the cervical portion of the tooth at the cemento
enamel junction upto the apical foramen
First demonstrated microscopically
in 1835
by Franke and Rachkov,
two pupils of Purkinje
Anatomically- part of tooth
Functionally- part of periodontium

4. Development of Cementum
INITIATION
HERS- corono-
apical extension
of the IEE & OEE
induces secretion
of enamel protein
Facing
ectomesenchymal
cells of the dental
papilla
differentiate into
the odontoblasts
Odontoblasts
start froming the
pre dentin
HERS becomes
interupted &
ectomesenchymal
cells of inner
portion of dental
follicle come in
contact with the
pre dentin
Em cells of the
follicle receive
signal from
dentin &
surrounding
HERS cells &
differentiate into
cementoblasts

6. Molecular factors regulating cementogenesis

7. Physical characteristics
 Hardness: Less than dentin
 Colour: Light yellow with dull surface & lighter than dentin
 Thickness: Variable, thinnest at CEJ (20 – 50μm) & thickest at apex
(150 – 200μm). Apical foramen is surrounded by cementum.
Cementum is thicker in distal surface than mesial surface probably
because of the functional stimulation from mesial drift. - Average
thickness – 95µm at Age 20; 215 µm at age 60.
 It is permeable (As age progress the permeability of cementum
diminishes)

8. Chemical characteristics
 On dry weight basis, cementum of fully formed permanent teeth
contains
 Inorganic substances (45-50%)
 Organic substances and water (50-55%)

9. Inorganic portion
 Hydroxyapatite (Calcium & Phosphate)
 Trace elements like
- Copper
- Fluorine
- Iron
- Lead
- Potassium
- Silica
- Sodium
- Zinc
 Cementum has highest fluoride content of all mineralized tissues

10. Organic portion
 Collagen: Type I predominant (90%)
- Others include type III (5%), V, XII & XIV
 Matrix proteins
 Proteoglycans
 Osteopontin
 Osteonectin
 Osteocalcin
 Fibronectin
 Bone sialoprotein

11. Organic portion
 Protein extracts of mature cementum
 -promote cell attachment & migration
 -stimulate protein synthesis for gingival fibroblasts & PDL cells
 Bone sialoprotein & osteopontin
 -differentiation of progenitor cells to cementoblasts

12. HISTOLOGY OF CEMENTUM
Histology section of cementum show:
a. Cells, Fibres, Ground substance
b. Cemento enamel junction
c. Cemento dentinal junction

13. CELLS OF CEMENTUM
The cells associated with cementum
are
1. Cementoblasts.
2. Cementocytes.
3. Cementoclasts.

14. Cementoblasts
• Characteristics- Numerous mitochondria
• Well formed golgi apparatus
• Large number of granular endo plasmic reticulum
• synthesize collagen and protein polysaccharides, which make up the
organic matrix of cementum
• After some cementum is laid down, its mineralization begins
•
• The cells are found lining the root surface

15. Cementocytes
 spider shaped cells & are the characteristic feature of cellular
cementum
 during the formation of cellular cementum, cementoblasts become
entrapped with in their own matrix due to rapid deposition & are called
cementocytes
 similar to osteocytes & they lie in spaces known as lacunae
 haphazardly arranged & widely dispersed

17.  canalicular processes branch & frequently anastomose with those of
neighboring cell
 processes are directed towards the PDL for nutrition
 deeper layers of cementum (60μm from nutrition) cementocytes
shows definite signs of degeneration such as cytoplasmic clumping,
vesiculation & sometimes empty lacunae

18. Cementoclasts
 found in Howship’s lacunae
 unilocular/ multilocular cells
 function: resorption of cementocytes
 major role: resorption and repair

19. Incremental lines of cementum
-referred to as “Incremental lines of Salter”
-represent rhythmic periodic deposition of cementum
-appear as dark lines running parallel to root surface
-seen in both acellular & cellular cementum but more prominent
in acellular cementum
-best seen in decalcified sections under light microscopy
-highly mineralized areas with less collagen & more ground substance

21. Types of cementum
By location:
Radicular cementum
Coronal cementum
By cellularity
Cellular cementum (Secondary cementum)
Acellular cementum (Primary cementum)
By the presence of collagen fibrils in the matrix
Fibrillar cementum
Afibrillar cementum
By the origin of the matrix fibers
Extrinsic fibre
Intrinsic fibre
Mixed fibre

22. Acellular cementum
 first to be formed
 covers cervical 3rd or half of the root
 does not contain cells
 formed before the tooth reaches occlusal plane
 thickness 30-230um
 composed mostly of Sharpey’s fibers (role in supporting tooth) –fibers
enter at right angles (embedded deep) –size, number & distribution of
fibers increases with function –calcified all along except at CEJ
 also contains intrinsic calcified collagen fibrils

25. Cellular cementum
 secondary formed cementum
 contains cemenotcytes
 formed after the tooth reaches the occlusal plane
 less calcified than acellular type
 thicker than acellular cementum
 Sharpey’s fibers occupies a smaller portion –completely or partially
calcified –uncalcified core

29. 2 sources of Collagen fibers
extrinsic intrinsic fibers
Based on the nature and origin of organic
matrix

30.  Extrinsic fibers -known as Sharpey’s fibers -embedded portion of
the principal fibers of PDL
 formed by fibroblast

31.  Intrinsic fibers -belong to cementum
 formed by cementoblast
-cementoblast also form noncollagenous components of interfibrillar
ground substance, such as PG, GP & PP

32. Schroeder Classification (1986)
ACELLULAR AFIBRILLAR CEMENTUM
ACELLULAR EXTRINSIC FIBRILLAR CEMENTUM
CELLULAR MIXED STRATIFIED CEMENTUM
CELLULAR INTRINSIC FIBER CEMENTUM
INTERMEDIATE CEMENTUM

33. Acellular Afibrillar Cementum
 Contains neither cells nor extrinsic or intrinsic collagen fibers
 Product of cementoblasts & is found as coronal cementum
 Thickness ------1-15um
 Lacks collagen and hence plays no role in attachment
 Deposited over enamel and dentin in proximity to CEJ
 Developmental anomaly as a result of disruption in reduced
dental epithelium that permit follicular cells to come in contact
with enamel surface & differentiate into cementoblasts

34. Acellular extrinsic fiber cementum
 Composed of densely packed bundles of sharpey’s fibers & lack cells
 Product of fibroblast & cementoblast
 Found in cervical 3rd of root -may extend apically
 Thickness between 30-230um
 Only type of cementum seen in single
rooted teeth
 Cementoid is not found
 Main function is anchorage especially
in single rooted teeth

35. Cellular mixed stratified cementum
 Composed of extrinsic (sharpey’s) & intrinsic fibers & contain cells
 Extrinsic (5 – 7 m) and Intrinsic (1 – 2 m)
 Co-product of fibroblasts & cementoblast
 Appears in apical 3rd of roots, apices
& in furcation areas
 Thickness 100 -1000um
 Intrinsic fibers are uniformly
mineralized but the extrinsic fibers
are variably mineralized with some
central unmineralized cores

36. Cellular intrinsic fiber cementum
 Contains cells and intrinsic collagen fibers
 Formed by cementoblasts & it fills resorption lacunae
 Majority of fibers organized parallel to the root surface
 Cells have phenotype of bone forming cells
 Very minor role in attachment (virtually absent in incisors and
canine teeth)
 Corresponds to cellular
cementum and is seen in
middle to apical third and
intrerradicular cementum

37. Intermediate cementum
 Ill defined zone near the cementodentinal junction of certain teeth
 Contain cellular remnants of Hertwig’s sheath
 Embedded in calcified ground substances

38. Cementodentinal junction
 Interface between dentin & cementum
 In deciduous teeth---- Scalloped
 In permanent teeth---- Smooth
 Areas of dentin adjacent to CDJ appear granular in ground section due
to coalescing and looping of terminal portion of dentinal tubules and is
called TOMES GRANULAR LAYER
 Terminal apical area of cementum where it joins the internal root canal
dentin
 During RCT obturating material should be at the CDJ
 No increase/decrease in width (2-3µm)

40. Cementoenamel junction
 Relation between cementum & enamel at the cervical region of
teeth is variable

41. FUNCTIONS
• Provide medium for attachment to the collagen
fibers of the periodontal ligament
• Cementum is harder than alveolar bone and is
avascular and does not show resorption under
masticatory or orthodontic forces
• Thus during heavy orthodontic forces tooth
integrity is maintained and alveolar bone being
elastic in nature changes its shape, fulfilling
orthodontic requirement.

42. FUNCTIONS
• Functions as a covering for root surface, a seal for open dentinal
tubules. By providing this seal it prevents sensitivity that can occur on
dentinal exposure
• Cementum has property of continuous deposition thus it repairs the
damage such as fracture or resorption of root surface
• Cementum can aid in maintaining the teeth in functional occlusion if
deposited at apical aspect especially in patients with chronic bruxism –
passive eruption

43. Cementum Resorption and Repair
Permanent teeth do not undergo physiologic resorption as do primary
teeth.
However, the cementum of erupted as well as unerupted teeth is
subject to resorptive changes that may be of microscopic proportion or
sufficiently extensive to present a radiographically detectable alteration
in the root contour.

44. Local conditions
 Trauma from occlusion
 Orthodontic movement
 Cysts
 Tumors
 Pressure from malaligned erupting teeth
 Teeth without functional antagonist
 Periapical disease
 Periodontal disease

45. Systemic conditions
 Calcium deficiency
 Hypothyroidism
 Hereditary fibrous osteodystrophy
 Paget’s disease

46. •Cementum resorption appears
microscopically as baylike concavities in
the root surface
•Multi-nucleated giant cells and large
mononuclear macrophages are generally
found adjacent to cementum undergoing
active resorption
•Several sites of resorption may coalesce
to form a large area of destruction

47. •The resorptive process may extend into
the underlying dentin and even into the
pulp, but it is usually painless
•Cementum resorption is not necessarily
continuous and may alternate with periods
of repair and the deposition of new
cementum
•The newly formed cementum is
demarcated from the root by a deep
staining irregular line, termed a reversal
line, which delineates the border of the
previous resorption

48. • Repair of cementum is a process to heal the damage caused by
resorption or cemental fracture
•Cementum repair requires the presence of viable connective tissue
•If epithelium proliferates into an area of resorption, repair will not take
place. Cementum repair can occur in devitalized as well as in vital teeth
ANATOMIC FUNCTIONAL
REPAIR

49. ANATOMIC REPAIR:
The root outline is re-established as it was before cemental resorption. It
generally occurs when the degree of destruction is low.
Cementum resorption is repaired by formation of cellular and acellular
cementum.
FUNCTIONAL REPAIR:
In cases of large cemental resorption or destruction, repair does not re
establish the same anatomic contour as before. To maintain the width of
PDL, 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 as functional
repair.

51. Effect of ageing on cementum
 With aging the surface of cementum becomes more irregular This is
caused by calcification of some fiber bundles where they were
attached to cementum
 Cemental width may increase (5-10 times) with increasing
age(deposition continues after eruption)
 Increase in width is greater apically & lingually
 In ageing, a continuous increase of cementum in apical zone may
result in obstruction of apical foramen

53. Exposure of cementum to the oral
environment
•Cementum becomes exposed to the oral environment in cases of
gingival recession and as a consequence of loss of attachment in
pocket formation
•The cementum is sufficiently permeable to be penetrated in these
cases by organic substances, inorganic ions, and bacteria
•Bacterial invasion of the cementum occurs commonly in periodontal
disease
•Caries of the cementum also can develop

54. Clinical considerations
•In periodontal pockets, pathologically exposed cementum, altered
cementum interfere with healing
•Root planing (hypomineralised cementum)
•Cellular cementum- avascular, no nerve supply
-scaling produces no pain, but if cementum is removed, dentin is exposed
causes sensitivity
•Precementum – natural barrier to excessive apical migration of junctional
epithelium
•Biomodification of root surface

55. The surface on which
plaque & calculus
artach. Role of
therapy is to remove
these accretions as a
part of the treatment
plan.
It forms the inner wall
of the periodontal
pocket.
This tissue is
relatively static as
compared to
surrounding dynamic
tissues, so any change
will have long term
effects.
Its intimately involved
in all phases of the PD
process so it must be
returned to a healthy
state before any
progress in deisease
control, soft tissue
regeneration & repair.
ROLE OF CEMENTUM IN PERIODONTAL DISEASE
DCNA Vol 24. No. 4, 1980 by
Joseph J. Aleo

56. Changes in cementum associated with
periodontal disease
 Structural changes
 Pathologic granules in exposed cementum by Bass and Benson –
proven by SEM studies that vacoule like formations exist
 Partial demineralisation by Selvig
 Reprecipiation of dissolved minerals
 Decrease or loss of cross banding of collagen
 Subsurface condensation of organic material of exogenous origin

57. Changes in cementum associated with
periodontal disease
 Chemical changes
 increase in calcium & phosphate levels by 7-10% -increased
radiopacity in electron probe analysis by Selvig & Hal
 Increase in flouride coincides with Ca & P (1.3-1.9%)
 Decrease in sodium levels (0.3%)
 Absorption of Ca P & F –highly calcified –resistant to decay
 Absorbed materials –foreign to surrounding tissues
 Demineralisation/mineralisation of cementum –ability to absorb or
deplete mineral or organic compounds

58. Changes in cementum associated with
periodontal disease
 Cytotoxic changes
 Effects on Cell proliferation
 Hatfield & Baumhammers- inhibitory substance penetrates surface of
exposed cementum that prevents growth of epithelial cells in tissue
cuture
 Presence of endotoxins- Aleo et al 1974 –limit fibroblast proliferation –
detrimental to the arrest of disease
 Cementum bound endotoxins -50 times more toxic –heat resistant toxic
substances (Limulus amoebocyte lysate)
 Destructive physical changes –cavitation, partial demineralisation

59. Changes in cementum associated with
periodontal disease
 Cytotoxic changes
 Effects on Cell attachment
 Cultured human gingival fibroblasts do not attach to the diseased tooth
–Aleo et al 1975

60. Changes in cementum associated with
periodontal disease
 Cytotoxic changes
 Effects on Cell attachment
 Inhibitory principle of matrix- Morris 1975
 –diseased roots inhibited the development of implanted marrow
whereas demineralised healthy roots did not
 –demineralised diseased roots showed most inhibtion (masked by
superimposed apatite crystals) –toxins must have seeped into root
matrix during pocket formation & demineralisation removed the toxins
allowing development of marrow

61. Changes in cementum associated with
periodontal disease
 According to inhibitory principle of matrix –drastic phenol extraction
usually required to remove toxins from bacterial cell wall is not
neccesary to make diseased cementum receptive to cell attachment –
milder treatments may accomplish the same thing

62. Changes in cementum associated with
periodontal disease
 in early and moderate periodontitis -acellular cementum (coronal half of
the root) is affected
 damage extends to cellular cementum in most advanced and furcally
positioned lesions
 these surfaces are almost always covered by cellular cementum during
successful regeneration; whether this is adequate is unclear
(MacNeil and Somerman, 1999)

63. Role of cementum molecules in
periodontal regeneration
 growth factors and adhesion molecules present in
cementum are also active toward cells of the gingiva, periodontal
ligament, and alveolar bone
(Narayanan and Bartold,1996; Bartold et al., 2000)
 it is possible that these cementum components have the potential to
participate in the regeneration of these tissues

64. Role of cementum molecules in
periodontal regeneration
 not significant because the growth factors present in cementum remain
bound to the cementum matrix
 even if the inflammatory process releases them, their relative
concentrations are likely to
be less than those available from the blood and inflammatory cells
 therefore, contributions by cementum molecules to the
regeneration of other periodontal tissues are likely to be marginal

65. Effectiveness of Root planing in
removing toxins
 In vitro- human gingival fibroblasts attach normally to periodontally
diseased roots that have diseased cementum mechanically removed
 In vivo- Jones & O’Leary 1978
 -subgingival root planed
 -supragingival root planed
 -periodontally involved with calculus
 -gross scaled in vitro
 -healthy uninvolved
 All were planed and checked with Hartzell No. 3 explorer & then
assayed for endotoxin –planed had 1ng more endotoxin

66. Chemical modification of cementum
 Addition of zinc to cultures relieved endotoxin induced depression of
cellular proliferation
 Chelation of zinc enhanced cellular toxicity of endotoxin -Aleo
 Studies analysing effect of zinc on cell attachment are still underway
 Register & Burdick- tested effects of partial demineralisation by acid on
reattachment (adult dogs)
 Results –production of cementum pins –reattachment with
cementogenesis –repair of chronic interproximal defects –complete
alveolar bone repair over labial defects by 1 year

67. Related studies
 Root Cementum May Modulate Gene Expression During Periodontal
Regeneration: A Preliminary Study in Humans
Goncxalves PF et al J Periodontol February 2008
 Effect of two different approaches for root decontamination on new
cementum formation following guided tissue regeneration: A
histomorphometric study in dogs
Goncxalves PF et al J Periodontal Res 2006
 Role of diseased root cementum in healing following treatment of
periodontal disease. An experimental study in the dog
Nyman S et al J Periodontal Res 1986

68. DEVELOPMENTAL ANOMALIES OF
CEMENTUM
Enamel Projections
If amelogenesis does not stop before
the start of root formation, enamel may
continue to form over portions normally
covered by cementum.
Enamel Pearls
This consists of globules of enamel
on the root surface in cervical region (act
as plaque retentive areas)

69. Hypercementosis
•refers to a prominent thickening of the
cementum
•It may be localized to one tooth or affect
the entire dentition (Pagets disease)
•occurs as a generalized thickening of the
cementum, with nodular enlargement of
the apical third of the root

70. The etiology of hypercementosis
•spikelike type of hypercementosis -results
from excessive tension from orthodontic
appliances or occlusal forces
•generalized type -occurs in teeth without
antagonists, hypercementosis is interpreted
as an effort to keep pace with excessive tooth
eruption

71. •In teeth subject to low-grade
periapical irritation arising from pulp
disease, it is considered compensation
for the destroyed fibrous attachment to
the tooth

72. Cementoblastoma
•Only neoplasm of cementum
•Cementum like tissue is deposited in
roots of tooth as irregular or rounded
mass
•Age <25
•Often involves the mandibular molars or
premolars
•Tooth usually has a vital pulp
•Attached to root and may cause its
resorption, may involve the pulp canal,
grows slowly, tends to expand the
overlying cortical plates
•Enlargement produced is usually
asymptomatic

73. Cementoma
•Benign cementoblastoma / Cemental
Dysplasia
•Represents an unusual reaction of bone
•Caused due to occlusal trauma
•Present usually at apex of mandibular
incisors
•Almost exclusively found in black
persons
•Age 20-40 years
•Expansion of jaw

74. Concrescence
•Form of fusion which occurs after root
formation has been completed
•Thought to arise as result of traumatic
injury or crowding of teeth with resorption
of interdental bone so that two roots are
in approximate contact and become
fused by deposition of cementum
between them
•May occur before or after teeth have
erupted

75. Cementopathia
•In 1923, Gottlieb reported a patient with
fatal case of influenza and disease called
diffuse atrophy of bone.
•characterized by loss of collagen fibers in PDL
and their replacement by loose connective tissue
and extensive bone resorption resulting in the
widened PDL space

76. Cementopathia
•Gottlieb attributed this condition to
inhibition of continuous cementum
formation which he considered essential
for maintenance of PDL fibers.
•He then termed the disease as
CEMENTOPATHIA.

77. Hypophosphatasia
This is a hereditary disease that is characterized by the total absence
of cementum
It results in early loss of the teeth
It occurs because of the deficiency of enzyme alkaline phosphatase in
serum and tissues

78. Cementicles
-calcified bodies sometimes seen in the periodontal ligament
-may be round or ovoid -present singly or in multiple numbers near the
cemental surface
Origin
-not established -possibly degenerated epithelial cells form the nidus for
their calcification
-also believed could be due to trauma, the calcification of the ends of the
sharpey’s fibers occurs that can result in the formation

79. Cementicles
Types of cementicles:
Free cementicles : lamellated cemental bodies that
lie freely in the PDL
Attached cementicles : cemental bpdies which are
attached to the root surface

80. Ankylosis
•Fusion of the cementum and alveolar bone with obliteration of the
periodontal ligament is termed ankylosis
•occurs in teeth with cemental
resorption, may represent a form of
abnormal repair
•may develop after chronic
periapical inflammation, tooth
replantation, occlusal trauma
•results in resorption of the root and its gradual replacement by bone
tissue.

81. Conclusion
Cementum is an important tissue of the periodontium, the attachment
apparatus of the tooth and has an important role in tooth movements.
Cementum deposition is a continuous process but this tissue is
comparatively static as compared to the surrounding dynamic tissues
therefore it has to be taken in account while performing various dental
procedures.

82. References
 Perio 2000
 Clinical periodontology Carranza
 CEMENTUM- Recent concepts related to periodontal disease therapy –
Joseph J. Aleo (DCNA)
 Clinical preiodontology & implantology by LINDHE
 Shhafer’s textbook of oral pathology
 Oral histology & Embryology by Orbans
 Tencate’s oral histology

83. THANK YOU