The cementum is a specialised calcified substance covering the root of the tooth. The cementum is a part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament. This presentation covers the anatomy and pathologies associated with the cementum.

1. CEMENTUM
Presented by – Shraddha Kode

3. INTRODUCTION
• Calcified avascular mesenchymal tissue that forms the outer
covering of the anatomic root (Newman et al, 2006)
• Latin: ‘caementum’ Meaning: “quarried stone”.
• 2 main types- Acellular (Primary) Consist of calcified
Cellular (Secondary) interfibrillar matrix
and collagen fibrils

4. SIMILARITIES WITH BONE
• Diseases that affect the bone, often alter cementum’s properties as well.
Eg. Paget’s disease results in hypercementosis, hypophosphatasia results
in no cementum formation, etc.
• Composition is similar to that of bone
• Differences are
• Avascular
• Lack Haversian canals
• Not innervated
• Exhibits little or no remodeling
• Less readily resorbed – therefore permits orthodontic movement

5. PHYSICAL CHARACTERISTICS
 Hardness is less than that of dentin.
 Light yellow in color.
 Can be distinguished from enamel by its lack of luster &
its darker hue.
 Semi-permeable to a variety of materials.

6. CHEMICAL COMPOSITION
 Contains 45% to 50% inorganic substances & 50%
to 55% organic material & water.
 Cementum has the highest fluoride content of all
the mineralized tissues.
 Organic portion consists primarily of type I collagen
& protein polysaccharides (proteoglycans).

7. CLASSIFICATION
1. Based on location
1. Radicular cementum – it accounts for the bulk of cementum
2. Coronal cementum – it is cementum over enamel in humans it is
thin and poorly developed but it is better developed in herbivorous
animals.
2. Based on time of formation
1.Primary cementum formed before tooth eruption.
2.Secondary cementum formed after tooth eruption.

8. 3. Based on it’s cellularity
1. Acellular cementum – which lacks embedded cells.
2. Cellular cementum – in which cells are located within the
mineralized matrix.
4. Based on the presence or absence of collagenous fibrils
• Afibrillar cementum – it lacks dense array of collagen fibrils although
rare isolated fibrils will be present.
• Fibrillar cementum – Contains well defined densely packed collagen
fibrils in it’s matrix.

9. 5. Based on the origin of collagenous fibrils
• Extrinsic fibers-, which are formed due to cementoblasts activity.
• Intrinsic fibers – incorporation of the periodontal ligament fibers.

10. Acellular Cementum Cellular Cementum
Location Coronal 2/3rd Apical 1/3rd
Function Attachment Protection, maintaining teeth in functional occlusion - minor role
in attachment.
Cellularity Not Present Present
Structure Microscopically - structure less
EM – Striation are seen
Laminated appearance
Fiber arrangement Extrinsic fibers – Parallely arranged perpendicular to root
surface
Intrinsic fibers – parallel to root surface
Extrinsic fibers – larger, haphazardly arranged.
Mineralisation Fully mineralised extrinsic fibers Intrinsic fibers – mineralised uniformly
Exrrinsic fibers – less mineralised
Speed of formation Slow and constant Rapid and irregular
Mode of secretion by cells Unipolar Multipolar
Cementoid Absent Present

11. ACELLULAR CEMENTUM CELLULAR CEMENTUM

12. Classification by SCHROEDER in 1986
ACELLULAR AFIBRILLAR CEMENTUM (AAC)
• No cells no extrinsic intrinsic collagen fibres
• Product of cementoblasts
• Found as coronal cementum in humans
• Thickness of 1 to 15 Am

13. ACELLULAR EXTRINSIC FIBRE CEMENTUM (AEFC)
• Composed of densely packed bundles of Sharpey’s fibres
• Lacks cells
• Product of fibroblasts and cementoblasts
• Cervical third of roots in humans
• Thickness – 30 and 230 Am

14. CELLULAR MIXED STRATIFIED CEMENTUM (CMSC)
• Composed of extrinsic intrinsic fibres and cells
• Produced by fibroblasts and cementoblasts
• Apical third of roots and in furcation areas
• Thickness – 100 to 1000 gym

15. CELLULAR INTRINSIC FIBRE CEMENTUM (CIFC)
• Contains cells
• No extrinsic fibres
• Formed by cementoblasts
• Fills resorption lacunae

16. INTERMEDIATE CEMENTUM
• First layer of cementum is actually formed by the inner cells
of the HERS and is deposited on the root’s surface is called
intermediate cementum or Hyaline layer of Hopewell-Smith
• Deposition occurs before the HERS disintegrates

17. • Intermediate cementum is situated between the granular
dentin layer of Tomes and the secondary cementum that is
formed by the cementoblasts (which arise from the dental
follicle)
• Approximately 10 m thick and mineralizes greater than
the adjacent dentin or the secondary cementum

18. SHARPEY’S FIBRES
• Connective tissue fibers from PDL pass between the
cementoblasts into the Cementum.
• These fibers are known as
“ SHARPEY’S FIBERS”
• They are embedded in the cementum & serve as an
attachment for the tooth to surrounding bone

20. Hertwig’s Epithelial Root Sheath and Root
formation
Hertwig's epithelial root
sheath formation
Induction of
ectomesenchymal pulp
cells – possibly by
some enamel protein.
Differentiation of
odontoblasts
Predentin formation
Fragmentation of HERS
Reciprocal inductive
signal to the dental
follicle
Differentiation of
cementoblast
Cemental deposition
Apoptosis of HERS and
some cells remain as
epithelial rests of
malassez.

21. MINERALISATION
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.

22. INCREMENTAL LINES OF SALTER
 In both acellular and cellular cement incremental lines run
roughly parallel with the root surface.
 These lines represent “Rest Periods” in cementum formation.
 These are formed by fiber-free amorphous substance and
represent intervals between successive deposition of cement
and are called incremental Lines of Salter.
 Histochemical study indicates that the incremental lines are
highly mineralized areas with less collagen and more ground
substance.

24. PERMEABILITY OF CEMENTUM
• Cellular and acellular cementum are very permeable and
permit the diffusion of dyes from the pulp and external root
surface.
• In cellular cementum, the canaliculi in some areas are
contiguous with the dentinal tubuli
• The permeability of cementum diminishes with age

25. CEMENTOENAMEL JUNCTION
3 TYPES
• 60% to 65% - cementum overlaps the enamel
• 30% - edge-to-edge butt joint exists
• 5% to 10% - cementum and enamel fail to meet
(Gingival recession may result in accentuated sensitivity
because the dentin is exposed)

26. Normal variations in tooth
morphology at the
cementoenamel junction

27. FUNCTIONS
1- Acts as a medium for attachment of collagen fibers of PDL
(Sharpey’s fibers).
2- The continuous formation of cementum keeps the
attachment apparatus intact.
3- Cementum deposition apically compensate for the attrition.
4- It is a major reparative tissue
( as in case of fracture or resorption of root)

28. CEMENTUM IN DISEASE
• HYPERCEMENTOSIS
Hypercementosis is characterized by cementum formation
beyond the physiologic limits of the tooth.
This excessive amount of cementum might lead to an
abnormal thickness of the apex that becomes round-shaped
and/or with the root appearance altered macroscopically

29. • CONCRESCENCE
Union of two adjacent teeth by cementum.
CAUSE - developmental union by cementum
Traumatic injury or crowding of teeth with resorption of the
interdental bone repaired by cementum

31. • CEMENTICLES
Abnormal,calcified bodies in the periodontal ligament
Generally they seem to form first on cellular debris, such as the
epithelial root sheath remnants.
Usually ovoid or round
Appearance similar to denticles
Size ranges from 0.1- 0.4 mm.
Formed as a response to local trauma or hyperactivity
Appear in increasing numbers in the aging person

32. • FREE CEMENTICLES
• ATTACHED CEMENTICLES
• EMBEDDED CEMENTICLES

33. • CEMENTAL SPIKES
It is uncommon condition characterized by occurrence of
small spikes or out growth of cementum on root surface.
It may occur due to occusal trauma.
Exact mechanism of formation is not known - calcification
of Sharpey’s Fibres???

34. • CEMENTAL CARIES
Hazen described it as soft progressive lesion found any where
an root surface that has lost connective tissues attachment
and is exposed to oral environment.
Micro-organisms appear to invade the cementum along
sharpey’s fibers or between bundles of fibers.
Since cementum is formed in concentric layers, micro-
organisms spread in lateral direction between various layers.
Once it involves dentin the process is identical to dentin
caries.

35. • ANKYLOSIS
Fusion of cementum and alveolar bone with obliteration of
periodontal ligament
It occurs due to:-
1) Cemental resorption
2) Chronic periapical inflammation
3) Tooth replantation
4) Occlusal trauma

36. • HYPOPHOSPHATASIA
• A rare familial disease, characterized by incomplete bone
mineralization.
• First described by Rathbun (1948).
• Characterized by low levels of serum kidney and bone alkaline
phosphatase and elevated levels of phosphoethanolamine in serum
and urine (Watanabe et al, 1993).
• Skeletal abnormalities (rickets, osteomalacia, poor cranial bone
formation) and premature loss of the primary teeth are common
findings.

37. • BENIGN CEMENTOBLASTOMA
It is neoplasm of functional cementoblasts which forms large masses
of cementum or cementum like tissues on tooth root.
Associated tooth is vital
Slow growing and causes expansion of cortical plates.
Radigraphic features
A tumor appears to attached to roots.
Well circumscribed dense radiopaque mast surrounded by thin
radiolucent border.

38. CENTRAL LESIONS
Cemento-osseous dysplasia (osseous dysplasia)
1 Focal cemento-osseous dysplasia
2 Periapical cemento-osseous dysplasia
(osseous dysplasia, cemental dysplasia, cementoma)
3 Florid cemento-osseous dysplasia
Cementifying fibroma
(cemento-ossifying fibroma, ossifying fibroma)
Familial gigentiform cementoma (True cementoma)

39. CONCLUSION
Specialized tissue evolved for special function
Functionally part of the dynamic unit of Periodontium
Anatomically part of the root
Regeneration of cementum  Regeneration of
periodontium