3. Contents:
ï± Introduction
ï± Development of cementum
ï± Molecular factors affecting cementogenesis
ï± Physical characteristics
ï± Chemical characteristics
ï± Histology of cementum
ï± Classification
ï± Cementodentinal junction
ï± Cementoenamel junction
4. ï± Functions
ï± Cementum resorption and repair
ï± Effects of ageing on cementum
ï± Cementum in oral environment
ï± Role of cementum in periodontal disease
ï± Changes in cementum in periodontal pathology
ï± Effectiveness of root planing
ï± Developmental anomalies
ï± Conclusion
ï± References
7. âȘ Begins at the cervical portion of the tooth at the cemento
enamel junction upto the apical foramen.
âȘ According to Denton,cementum was first demonstrated
microscopically by Fraenkel and Raschkow (1835) and
Retzius (1836) and has since become a part of general
knowledge in dentistry.
âȘ The word cementum originated from the latin word âcementâ
which means quarried stone.
âȘ Anatomically-part of tooth
Functionally-part of periodontium
8. DEFINITION
âȘ Cementum is the calcified, avascular mesenchymal tissue that
forms the outer covering of the anatomic root.
(Carranza 13th south asian edition)
âȘ Cementum is a hard, avascular connective tissue that covers the
root of the teeth.
(Ten Cateâs oral histology 9th edition)
âȘ Cementum is the mineralized dental tissue covering the
anatomic roots of human teeth.
(Orbanâs oral histology and embryology 13th edition)
9. âȘ The cementum is a specialized mineralized tissue
covering the root surfaces and, occasionally, small
portions of the crown of the teeth.
(Lindhe 6th edition)
âȘ The thin, calcified tissue of ectomesenchymal
origin covering the roots of teeth in which
embedded collagen fibers attach the teeth to the
alveolus.
(Glossary of Dental Implantology)
10. Development of cementum
HERS-Corono apical
extension of IEE and
OEE induces the
secretion of enamel
proteins
Facing the
ectomesenchymal
cells of the dental
papilla diffrentiate
into odontoblasts
Odontoblasts start
forming the
predentin
Some cells from the fragmented root sheath form discrete masses
surrounded by a basal lamina k/as Epithelial cell rests of malassez which
persists in the mature PDL.
11. HERS becomes
interrupted &
ectomesenchymal cells of
inner portion of dental
follicle comes in contact
with the predentin
EM cells of the follicle
receive signals from
dentin & surrounding
HERS cells;diffrentiates
into cementoblasts
Cementoblasts lay down
cemental matrix which
undergoes maturation and
subsequently gets
mineralised resulting into
cementum formation
14. Physical characteristics
âȘ Colour-
light yellow in colour
dull surface-lacks lusture
darker hue than enamel
âȘ Hardness-
less than dentin
âȘ Permeablility-
more permeable than dentin
decreases with age
âȘ Thickness-
thinnest at CEJ 20-50 ”m
thickest at apex 150-200”m
15. Chemical characteristics
âȘ On dry weight basis,a fully formed permanent teeth consists
of-
Inorganic substance
45-50%
âą Calcium phosphate in the form of hydroxy apatite crystals
Ca10(PO4)6(OH)2
âą Highest fluoride content
16. ï type I COLLAGEN fiber
ï And protein polysaccharide-
proteoglycans,osteopontin,osteonectin,osteocalcin,
osteonectin, fibronectin,bone sialoprotein.
ï Other collagen âType III,V,VI,XII
17. Suggested Function Related to Cementogenesis
Growth Factors
Transforming
growth factor ÎČ
superfamily
(including bone
morphogenetic
proteins)
Reported to promote cell differentiation and
subsequently cementogenesis during
development and regeneration.
Platelet-derived
growth factor
and insulin-like
growth factor
Existing data suggest that platelet-derived growth
factor alone or in combination
with insulin-like growth factor promotes cementum
formation by altering cell
cycle activities.
Fibroblast growth
factors
Suggested roles for these factors are promoting cell
proliferation and migration
and also vasculogenesisâall key events for formation
and regeneration of
periodontal tissues.
Adhesion Molecules
Bone
sialoprotein
Osteopontin
These molecules may promote adhesion of selected
cells to the newly forming
root. Bone sialoprotein may be involved in promoting
mineralization, whereas
osteopontin may regulate the extent of crystal
growth.
Epithelial/Enamel
Proteins
Proteins
Epithelial-mesenchymal interactions may be involved
in promoting follicle cells
18. along a cementoblast pathway.
Some epithelial molecules may promote periodontal
repair directly or indirectly.
Collagens Collagens, especially types I and III, play key roles in
regulating periodontal
tissues during development and regeneration.
In addition, typeXII may assist in maintaining the
periodontal ligament space
versus continuous formation of cementum.
Gla Proteins
Matrix Gla
protein/bone Gla
protein
(osteocalcin)
These proteins contain Îł-carboxyglutamic acid, hence
the name Gla proteins.
Osteocalcin is a marker for cells associated with
mineralizationâthat is,
osteoblasts, cementoblasts, and odontoblastsâand is
considered to be a regulator
of crystal growth. It has also been proposed to act as a
hormone regulating energy
metabolism through several synergistic functions
favoring pancreatic ÎČ-cell
proliferation, increasing insulin secretion (in the
pancreas) and sensitivity in
peripheral tissues, and promoting energy expenditure (in
brown adipose tissue)
and testosterone production by Leydig cells in testes.
Matrix Gla protein appears
to play a significant role in preventing abnormal ectopic
calcification.
19. Transcription Factors
Runt-related
transcriptionfactor 2
(Runx-2)
Osterix
As for osteoblasts, these may be involved in
cementoblast differentiation.
Signaling Molecules
Osteoprotegerin These molecules mediate bone and root resorption
by osteoclasts.
Receptoractivated
nuclear
factor ÎșB ligand
Receptoractivated
nuclear
factor ÎșB
Sclerostin Antagonist of Wnt and promotes cementum
formation
Wingless-related
integration site
(Wnt)
Regulates stem cell populations and
differentiation of cementoblasts
Cementum-Specific Proteins
Cementum
protein 1
(cementumderived
protein
23)
May play a role as a local regulator of cell
differentiation and extracellular matrix
mineralization.
20. Histology of cementum
âȘ Histologically,cementum shows
a. Cells,fibers,ground substance
b. Cemento enamel junction
c. Cemento dentinal junction
23. ïŒ After the matrix is laid down,it begins mineralisation
ïŒ The cells are found lining the root surface
24. âą Cementocyte
ïŒ Spider shaped cells -cellular
cementum.
ïŒ During the formation of cellular
cementum, cementoblasts get
entrapped within their own
cemental matrix due to rapid
deposition resulting
in the formation of cementocyte.
25. ïŒ Similar to osteocytes,they lie in
lacunae.
ïŒ Canalicular processes branch and
anastosomes with adjacent cells.
ïŒ These processes are directed
towards PDL.
ïŒ Deeper layers of cementum(60”m
from nutrition)cementocytes shows
definite signs of degeneration such
as cytoplasmic clumping,
vesiculation & sometimes empty
lacunae.
26. Cementoclast
ïŒ Found in howshipâs lacunae
ïŒ Unilocular/multilocular
ïŒ Function-resorption of
cementocytes
ïŒ Major role-resorption and repair
27. Incremental lines of salter
âȘ These lines represent rhythmic periodic deposition of cementum
âȘ Appears as dark lines running parallel
to root surface
ï§ Highly mineralized areas with less
collagen & more ground substance
ï§ Seen in both acellular and cellular
cementum
ï§ Predominantly in acellular cementum
28. Types of cementum
i.Based on location
a.radicular cementum
b.coronal cementum
ii.Based on cellularity
a.Acellular cementum
b.Cellular cementum
iii.Based on presence of collagen fibers in matrix
a.Afibrillar cementum
b.Fibrillar cementum
29. ACELLULAR CEMENTUM CELLULAR CEMENTUM
âą Primary cementum âą Secondary cementum
âą Present on cervical 3rd or half âą present on apical 3rd of the root
of the root
âą cells are absent âą cells are present
âą forms before the tooth reaches âą forms after the tooth reaches the
the occlusal plane the occlusal plane
âą more calcified âą less calcified
âą sharpeyâs fibers are main compo âą sparse number of sharpeyâs fibers
-nent are present
âą perpendicular to root surface âą parallel to root surface
âą rate of development is faster âą rate of development is slower
âąincremental lines are wide apart âą incremental lines are closer
⹠thickness ranges from 30-230”m ⹠thickness ranges from 150-200”m
30. iv. Based origin of the matrix fibers
a.extrinsic fiber
b.intrinsic fiber
c.mixed fiber
ï§ Extrinsic fiber-
â Also known as âsharpeyâs fiberâ
â Embedded portion of the principal
fibers of PDL
â Formed by fibroblasts
31. ï§ Intrinsic fiber
â Belongs to cementum
â Formed by cementoblast
Intrinsic
fibers of
cementum
32. Mixed fiber
â Composed of extinsic sharpeyâs fiber & intrinsic fiber
â Co-product of cementoblast and fibroblast
Mixed fibers of cementum
33. Schroeder classification(1986)
i. Acellular afibrillar cementum(AAC)
ii. Acellular extrinsic fiber cementum(AEFC)
iii. Cellular mixed stratified cementum(CMSC)
iv. Cellular intrinsic fiber cementum(CIFC)
34. ï±Acellular afibrillar cementum(AAC)
âȘ contains neither cells nor extrinsic or intrinsic
collagen fibers.
âȘ only mineralised ground substance.
ï§ product of cementum,seen in crown portion
of tooth
âȘ thickness - 1-15”m
âȘ no known fuction around CEJ.
35. ï± Acellular extrinsic fiber cementum(AEFC)
ï§ densely packed bundles of sharpeyâs fiber,
no cells.
ï§ co-product of fibroblast & cementoblast.
ï§ found in cervical 3rd of root,may extend
apically.
ï§ thickness- 30-230”m
ï§ function-anchorage in especially single
rooted teeth.
.
.
36. ï± Cellular mixed stratified cementum(CMSC)
âȘ composed of both intrinsic & extrinsic
sharpeyâs fibers.
âȘ may contain cells.
âȘ co-product of fibroblast & cementoblast.
âȘ function-adaptation & repair
37. ï± Cellular intrinsic fiber cementum(CIFC)
-contain cells but no extrinsic collagen fiber.
-formed by cementoblasts.
-fills the resorption lacunae.
38. ï±Intermediate cementum-
is a poorly defined zone near the cementodentinal junction
of certain teeth that appear to contain cellular remnants of
Hertwig sheath embedded in calcified ground substance.
- seen in apical 3rd of root and apices, & in furcation area.
-thickness- 10-1000”m
-function-adaptation of fibers
39. Cementodentinal junction
âȘ Interface between dentin and
cementum.
âȘ In deciduous teeth-scalloped
permanent teeth-smooth.
âȘ Areas of dentin adjacent to CDJ
granular in ground substance
due to coalescing and looping the
terminal portion of dentinal tubules
and is called âTomes Granular Layerâ.
40. ï§ Terminal apical area of cementum where it joins
the inteernal root canal dentin.
ï§ During RCT,the obturating material should be at
CDJ.
ï§ No increase /decrease in width(2-3”m)
41. Cementoenamel junction
âȘ It is the preface between cementum & enamel at cervical region
of teeth is variable.
âȘ It is also an important landmark as a clinical consideration while
scaling and root planing.
42. Funtions of cementum
âȘ Provides medium for the attachment of collagen fibers of PDL.
âȘ Cementum is harder than alveolar bone & is avascular and
doesnât show resorption on masticatory or orthodontic forces.
43. âȘ Thus during heavy orthodontic forces tooth integrity is
maintained & alveolar bone being elastic in nature changes its
shape,fulfilling orthodontic requirements.
44. âȘ Acts as a covering for root surface, a seal for open dentinal
tubules.
âȘ Prevents dentinal tubules from
sensitivity.
ï±Reparative nature
âȘ Aid in maintaining the teeth in functional occlusion (in
chronic bruxism, deposition of cementum on apical aspect of
the teeth) [passive eruption].
45. Cementum resorption and repair
âȘ Permanent teeth do not undergo phyioslogic resorption as
primary teeth.
âȘ Local factors-
âȘ Systemic factors- Ca deficiency,
hypothyroidism,pagetâs disease,
Hereditary fibrous
osteodystrophy
âȘ Microscopically ,bay-like concavities seen over tooth surface.
Multi nucleated giant cells, mononuclear macrophages are
generally found adjacent to the site of active resorption.
âȘ Painless
46. âȘ Reversal line-?
âȘ Repair â i.anatomic repair
ii.functional repair
âȘ Occurs in vital and non vital tooth both
47. Effects on ageing in cementum
âȘ Becomes irregular due to calcification of some bundle fibers
where they were attached to cementum
âȘ Cemental width may increase 5-10 times
(deposition continues after eruption)
âȘ Increase in width is greater apically &
lingually
âȘ In ageing, a continuous increase of
cementum in apical zone may
result in obstruction of apical
foramen
48. What happens to cementum when
exposed to oral cavity?
ï±Cementum becomes exposed to the oral environment in cases
of gingival recession and as a consequence of loss of
attachment in pocket formation
ï±The cementum is sufficiently permeable to be penetrated in
these cases by organic substances, inorganic ions, and
bacteria
ï±Bacterial invasion of the cementum occurs commonly in
periodontal disease
ï± Cemental caries
49. Clinical considerations
ï§ In periodontal pockets, pathologically exposed cementum,
altered cementum interfere with healing
ï§ Root planing (hypomineralised cementum)
ï§ Cellular cementum- avascular, no nerve supply -scaling
produces no pain, but if cementum is removed, dentin is
exposed causes sensitivity
ï§ Precementum â natural barrier to excessive apical
migration of junctional epithelium
ï§ Biomodification of root surface
50. Role of cementum in
periodontal disease
The surface on which plaque &
calculus is attached, the role
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 disease control,
soft tissue regeneration & repair.
ROLE OF CEMENTUM IN
PERIODONTAL DISEASE
DCNAVol 24. No. 4, 1980
by Joseph J. Aleo
51. Changes in cementum associated
with periodontal disease
âȘ Structural changes
âȘ Pathologic granules in exposed cementum by Bass and Benson
â proven by SEM studies that vacuole like formations exist
âȘ Partial demineralisation by Selvig et al
âȘ Reprecipiation of dissolved minerals
âȘ Decrease or loss of cross banding of collagen
âȘ Subsurface condensation of organic material of exogenous
origin
52. âȘ Chemical changes
âȘ increase in calcium & phosphate levels by 7-10% -increased
radiopacity in electron probe analysis by Selvig & Hal
âȘ Increase in flouride coincides with Ca & P (1.3-1.9%)
âȘ Decrease in sodium levels (0.3%)
âȘ Absorption of Ca P & F âhighly calcified âresistant to decay
âȘ Absorbed materials âforeign to surrounding tissues
âȘ Demineralisation/mineralisation of cementum âability to
absorb or deplete mineral or organic compounds
53. ï±Cytotoxic changes
âȘ Effects on Cell proliferation
-Hatfield & Baumhammers- inhibitory substance penetrates
surface of exposed cementum that prevents growth of epithelial
cells in tissue culture
-Presence of endotoxins- Aleo et al 1974 âlimit fibroblast
proliferation â detrimental to the arrest of disease
-Cementum bound endotoxins -50 times more toxic âheat
resistant toxic substances (Limulus amoebocyte lysate)
-Destructive physical changes âcavitation, partial
demineralisation
54. ï±Cytotoxic changes
âą Effects on Cell attachment
âą Cultured human gingival fibroblasts do not attach
to the diseased tooth âAleo et al 1975
55. Effects on Cell attachment
âą Inhibitory principle of matrix
âą Morris 1975
âą diseased roots inhibited the development of implanted
marrow whereas demineralised healthy roots did not
âą demineralised diseased roots showed most inhibtion (masked
by superimposed apatite crystals)
âą toxins must have seeped into root matrix during pocket
formation & demineralisation removed the toxins allowing
development of marrow
56. âȘ According to inhibitory principle of matrix â
âȘ drastic phenol extraction usually required to
remove toxins from bacterial cell wall is not
necessary to make diseased cementum receptive
to cell attachment â milder treatments may
accomplish the same thing
57. âȘ in early and moderate periodontitis -acellular
cementum (coronal half of the root) is affected
âȘ damage extends to cellular cementum in most
advanced and furcally positioned lesions
âȘ these surfaces are almost always covered by
cellular cementum during successful regeneration;
whether this is adequate is unclear.
(MacNeil and Somerman, 1999)
58. Role of cementum molecules in
periodontal regeneration
âȘ 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)
âȘ it is possible that these cementum components
have the potential to participate in the
regeneration of these tissues
59. âȘ not significant because the growth factors present
in cementum remain bound to the cementum
matrix
âȘ even if the inflammatory process releases them,
their relative concentrations are likely to be less
than those available from the blood and
inflammatory cells
âȘ therefore, contributions by cementum molecules
to the regeneration of other periodontal tissues
are likely to be marginal
60. Effectiveness of Root planing
in removing toxins
âȘ In vitro- human gingival fibroblasts attach normally to
periodontally diseased roots that have diseased
cementum mechanically removed
âȘ In vivo- Jones & OâLeary 1978
âȘ -subgingival root planed
-supragingival root planed
-periodontally involved with calculus
-gross scaled in vitro
-healthy uninvolved
âȘ All were planed and checked with Hartzell No. 3 explorer
& then assayed for endotoxin âplaned had 1ng more
endotoxin
61. Chemical modification of
cementum
Addition of zinc to cultures relieved endotoxin induced
depression of cellular proliferation.
âȘ Chelation of zinc enhanced cellular toxicity of endotoxin -
Aleo et al
âȘ Studies analysing effect of zinc on cell attachment are still
underway
âȘ Register & Burdick- tested effects of partial
demineralisation by acid on reattachment (adult dogs)
âȘ Results âproduction of cementum pins âreattachment with
cementogenesis
ârepair of chronic interproximal defects
âcomplete alveolar bone repair over labial defects by 1 year
62. Role of cementum in periodontal
regeneration
âȘ Not significant because the growth factors present in
cementum remains bound to the cemental matrix.
âȘ Even if the inflammatory process releases them, their
relative concentrations are likely to be less than those
available from the blood & inflammatory cells.
âȘ Therefore,contributions by cementum molecules to the
regeneration of other periodontal tissues are likely to be
marginal.
63. DEVELOPMENTAL ANOMALIES
LOCATED ON CEMENTUM
âȘ Enamel Projections
If amelogenesis does not stop before
the start of root formation, enamel
may continue to form over portions
normally covered by cementum.
64. âȘ Enamel Pearls
This consists of globules of enamel
on the root surface in cervical region
(act as plaque retentive areas)
65. Hypercementosis
âȘ refers to a prominent thickening of the cementum .
âȘ It may be localized to one tooth or
affect the entire dentition
(Pagets disease)
âȘ occurs as a generalized
thickening of the cementum,
with nodular enlargement of
the apical third of the root.
66. The etiology of Hypercementosis
âȘ spike like type of hypercementosis -results from
excessive tension from orthodontic appliances
or occlusal forces
âȘ generalized type -occurs in teeth without antagonists,
hypercementosis is interpreted as an effort to keep pace
with excessive tooth eruption
âȘ In teeth subject to low-grade periapical irritation arising
from pulp disease, it is considered compensation for the
destroyed fibrous attachment to the tooth
67. Factors leading to hypercementosis
âą TFO
âą Orthodontic movement
âą Pressure from non-aligned erupting
tooth
âą Cysts,tumors
âą Teeth without functional antagonist
âą Periapical disease
Local factors
âą Calcium deficiency
âą Hypothyroidism
âą Hereditary fibrous osteodystrophy
âą Pagetâs didsease
Systemic
factors
68. âȘ Other systemic disturbances that may lead to ormay be
associated with hypercementosis include
acromegaly,arthritis, calcinosis, rheumatic fever, and
thyroid goiter.
69. Cementoblastoma
ï§ Only neoplasm of cementum
ï§ Cementum like tissue is deposited
in roots of tooth as irregular or rounded
mass.
âąAge <25
ï§ Often involves the mandibular molars
or premolars
ï§ Tooth usually has a vital pulp
ï§ Attached to root and may cause its resorption, may involve the
pulp canal, grows slowly, tends to expand the overlying cortical
plates
ï§ Enlargement produced is usually asymptomatic
70. Cementoma
âąBenign cementoblastoma / Cemental Dysplasia
âąRepresents an unusual reaction of bone
âąCaused due to occlusal trauma
âąPresent usually at apex of mandibular
incisors
âąAlmost exclusively found in black
persons
âąAge 20-40 years
âąExpansion of jaw
71. Concrescence
âȘ Form of fusion which occurs after root
formation has been completed.
âȘ 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.
âȘ May occur before or after teeth have
erupted.
72. Hypophosphatasia
âȘ This is a hereditary disease that is characterized by the total
absence of cementum.
âȘ It results in early loss of the teeth.
âȘ It occurs because of the deficiency of enzyme alkaline
phosphatase in serum and tissues.
73. Cementicles
ï§ calcified bodies sometimes seen in the periodontal
ligament.
ï§ may be round or ovoid.
ï§ singly or in multiple numbers near the cemental surface.
ï±Origin
ï§ not established.degenerated epithelial cells form the nidus
for their calcification.
ï§ also believed could be due to trauma, the calcification of the
ends of the sharpeyâs fibers occurs that can result in the
formation.
74. âȘ Types of cementicles:
âȘ Free cementicles : lamellated
cemental
bodies that lie freely in the PDL.
âȘ Attached cementicles : cemental
bodies which are attached to the
root surface.
75. Ankylosis
âȘ âąFusion of the cementum and alveolar
bone with obliteration of the periodontal
ligament is termed ankylosis.
âąoccurs in teeth with cemental resorption,
may represent a form of abnormal repair.
âąmay develop after chronic periapical
inflammation, tooth replantation, occlusal
trauma.
âąresults in resorption of the root and its
gradual replacement by bone tissue.
76. Conclusion
âȘ Cementum is an important tissue of the periodontium,
the attachment apparatus of the tooth and has an
important role in tooth movements.
âȘ 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.
77. References
âȘ Carranza Clinical periodontology south asian edition 13th
âȘ CEMENTUM- Recent concepts related to periodontal
disease therapy â Joseph J. Aleo (DCNA)
âȘ LINDHEâs Clinical periodontology & implantology,6th edition
âȘ Shaferâs textbook of oral pathology, 6th edition
âȘ Orbanâs Oral histology & Embryology edition,14th edition
âȘ Tencateâs oral histology 9th edition