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By/ Dr. Hesham
Dameer
Cementum is part of the
    peridontium
THE PERIODONTIUM
The peridontium consists of those tissues which surrounds ,
support the tooth and is composed of :

Gingiva
Periodontal ligament
Cementum
Alveolar bone


      By/ Dr. Hesham
      Dameer
Gingiva
The gingiva is that part of the oral
mucosa which surrounds the tooth and
cover the alveolar bone .
In light-skinned individuals the gingiva
(G) can be readily distinguished from the
adjacent dark red alveolar mucosa (AM)
by its lighter pink color. Its apical border,
that separates it from the adjacent
alveolar mucosa, is the mucogingival
junction (MGJ). A similar tissue
relationship can be seen on the lingual
aspect of the mandible
AM, alveolar mucosa .G, gingiva .MGJ, mucogingival junction
AM,alveolar mucosa .F, floor of the mouth .G, gingiva .MGJ, mucogingival junction
Periodontal ligament
Dense connective fibers that connect the
cementum covering the root of the tooth
with the alveolar bone of the socket wall .
Principal fibers of the periodontal
ligament :
The periodontal fibers of the periodontal
ligament are primarily composed of
bundles of type I collagen fibrils. They
have been classified into several groups
on the basis of their anatomic location:
The following constitute the principal fiber
groups of the periodontal ligament:

1. Alveolar crest group
2. Horizontal group
3. Oblique group
4. Periapical group
5. Interradicular group




   By/ Dr. Hesham
   Dameer
Cementum


By/ Dr. Hesham
Dameer
Cementum is a hard connective
tissue that covers the root of the
tooth to furnish a medium into
which the principle fibers of the
periodontal ligament are
terminally inserted .



  By/ Dr. Hesham
  Dameer
Cementum

It begins at the cervical portion of
     the tooth at the cemento-
     enamel junction and continues
     to the apex.
Cementum furnishes a medium for
     the attachment of collagen
     fibers that bind the tooth to
     surrounding structures.




  By/ Dr. Hesham
  Dameer
Physical Characteristics
  1-Color
Light yellow
Lighter in color than dentin
  2- Thickness
Acellular cementum (20-50 m)
Cellular cementum (150-200 m)

 3- Permeability
 Permeable from dentin and PDL sides.
Cellular C is more permeable than acellular C.
Chemical Composition
45-50 % Inorganic                   50-55% Organic
   substances                         substances

                      collagen
   consists of
                      fibers         protein
    calcium
phosphate in the      embedded
form of hydroxy-      in a ground
 apatite crystals     substance .       Polysaccharides




Cementum contains the greatest amount of
fluoride in all mineralized tissues
     By/ Dr. Hesham
     Dameer
Cementogenesis

•     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
Cementogenesis


Cementum formation in the developing tooth is preceded by
the deposition of dentin along the inner aspect of Hertwig‘s
sheath . Once dentin formation is underway breaks occur in
the epithelial root sheath allowing the newly formed dentin to
come in direct contact with the connective tissue of the
dental sac , the undifferentiated mesenchymal cells derived
from the dental sac differentiate into cementoblasts . These
cells have the ultrastructural characteristics typical of cells
actively synthesis protein and polysaccharide .
The main product of cementoblasts is collagen and ground
substances , both constitute the organic component of
cementum .
The inorganic material of cementum is calcium phosphate
Hydroxy apatite .
Cementogenesis




       After degeneration of the
       epithelial root sheath
       ectomesenchymal cells from
       the inner portion of the dental   Odontoblast
       follicle differentiate and
       become cementoblasts




       cementoblasts.


    By/ Dr. Hesham
    Dameer
Growth of cementum is a rhythmic process and as a new
cementoid is formed, the old one is calcified . A thin layer of
cementoid can be observed on cemental surface which is
covered by cementoblasts .
The mineralization begins after forming the first layer of
matrix.


The mineral crystals is deposited within and between the
collagen fibers, the long axes of the crystals are arranged
parallel to the long axis of the collagen fibers .


 Sometimes crystals can be seen clustered into groups of
 nucleation centers as found in bone.
Cementogenesis

                             cementoid




Cementodentinal junction




                           Cementoblasts
Cementoblast is a protein forming and secreting cell.

   Maturation occur layer             Collagen fibers +
   by layer for the                  ground substance.
   collagen fibers
   D                        Cementum
                             Large open face nucleus




                                                    Cementoblasts
   Cementoblast




                               RER
                   Cementoid layer
                               Golgi apparatus
                               Mitochondria
                              Secretory granules
                              Alkaline phosphatase
Cementogenesis




  After reaching the full thickness the cementoblasts enter
       a quiescent stage.
  During matrix formation fibroblasts form collagen fibers
       (sharpey`s fibers), which become embedded in
       the matrix to provide attachment of the root to the
       surrounding bone. Those fibers are also called
       perforating fibers.
  .



     By/ Dr. Hesham
     Dameer
Remnants of the
                              Hertwig`s root
                              sheath, which
                              disintegrate into
                              the PDL are the
                              Malassez cells.

intermediate
cementum




          By/ Dr. Hesham
          Dameer
Histological structure :

cementum cover the root dentin from
cementoenamel junction to the root apex .

It is thinnest at this junction ( 20 – 50 μm ) but
becomes gradually thicker apicalward ranging
from 150 – 200 μm ) or more .




    By/ Dr. Hesham
    Dameer
Two forms of collagen are found in
cementum :

     * collagen fibrils
     * collagen bundles

The collagen fibrils are arranged in a very
complex fashion and constitute the main
bulk of the organic material of cementum.
The collagen bundles represent the
embedded portion of the principle fibers of
the periodontal ligament, that is Sharpey s
fibers .
Two types of cells are functionally concerned with
 cementum :
    * Cementoblasts
    * Cementocytes
Cementoblasts line the root surface and when active,
 they contain numerous mitochondria, well developed
 Golgi complex, and open-faced nucleus. However, in
 resting cementoblasts, these cytologic features
 become less pronounced .




     By/ Dr. Hesham
     Dameer
While cementum is being deposited,
cementoblasts retreat leaving behind the
formed cementum matrix. Occasionally,
however, cementoblasts become
entrapped in the forming matrix and then
known cementocytes .
Cementocytes are seen located in lacunae in cementum
  matrix and typically have numerous processes lying in
  canaliculi . These processes may branch and
  frequently anastomose with those of the adjacent
  cementocytes . This indicates that these cells are not
  functionally separated from each other . Because
  cementum is avascular tissue, thus the processes of
  the cementocytes are oriented toward the periodontal
  ligament for nutrition .
As a result of continuous phasic deposition of
  cementum, resting lines known Salter lines appear in
  cementum .


       By/ Dr. Hesham
       Dameer
Cementocytes
Cementocyte lacuna
Cementocyte canaliculi
       Cementocyte




Cementocyte process
Incremental Lines

• Incremental lines of Salter.

                         Incremental lines of Salter
Incremental lines of Salter




                              Dentin
Resting lines of Salter
Types of cementum :
I) Based on cellular connotation :
     1- Cementum containing cells :
           a. Cellular cementum
           b. Intermediate cementum
     2- Acellular cementum
II) Based on fibrillar connotation :
     1. Intrinsic fibers cementum
     2. Extrinsic fibers cementum
     3. Mixed fibers cementum
     4. Afibrillar cementum
I) Based on cellular connotation :
 1- Cementum containing cells :
     a. Cellular cementum is more frequently found on the
 apical half of the root where cementum does contain
 cementocytes in its matrix .

    b. Intermediate cementum
Intermediate cementum is a thin, amorphous layer of hard tissue
 approximately 10 micron thick.
Is more frequently seen in the apical two thirds of the roots of
 posterior teeth but rarely in incisors or primary teeth .

This type of cementum does not exhibit the characteristic
features of either dentin or cementum, while in regard to its
location, it is found intermediate between cementum and dentin
.
In respect to the involved cells observed in
intermediate cementum, there is argument about there
derivation :

1- The cells of the epithelial root sheath of Hertwig are
proposed to become entrapped while dentin or
cementum is being rapidly deposited .

2- Other concept claims that odontoblasts are trapped
on the outer dentin surface at the commencement of
dentinogenesis which subsequently being enclosed by
the forming cementum .
Cementogenesis




intermediate cementum
                        Cementoblasts
Remnants of the
                              Hertwig`s root
                              sheath, which
                              disintegrate into
                              the PDL are the
                              Malassez cells.

intermediate
cementum




          By/ Dr. Hesham
          Dameer
2- Acellular cementum :
The matrix of this type of cementum does not involve
      cementocytes . However, cementoblasts present
      on its outer surface and constitute an integral
      component of acellular cementum .
Acellular cementum may cover the root dentin from the
      cementoenamel junction to the root apex, but with
      frequent absence on the apical third of the root .
II) Based on fibrillar connotation :
    1. Intrinsic fibers cementum : the fibers are derived
      from the synthetic and secretory activity of
      cementoblasts .
2. extrinsic fibers cementum : in this form, the extrinsic
  fibers originate from the principal fibers of the
  periodontal ligament that is Sharpey s fibers .
3. mixed fibers cementum : it contains both intrinsic and
  extrinsic fibers .
4. Afibrillar cementum : as enamel is completely formed
  and become fully calcified, it is seen covered by the
  reduced enamel epithelium which is of paramount
  importance in protecting enamel, however, the
  reduced enamel epithelium may retract from the
  cervical region of enamel . This allows for the adjacent
  mesenchymal cells to invade and intervene between
  enamel and its covering epithelium . The
  mesenchymal cells differentiate into cementoblasts
  and deposit a particular type of cementum, that is,
  afibrillar cementum, on enamel surface .

       By/ Dr. Hesham
       Dameer
Cementoenamel Junction (CEJ)
• 3 patterns may be present
• 1) In approximately 60% of teeth cementum overlapping the cervical end of
  enamel for a very narrow area at the CEJ . This occurs as a result of
  premature degeneration or retraction of the reduced enamel epithelium at
  the cervical region of enamel . This allows for the adjacent mesenchymal
  cells to invade and intervene between enamel and its covering epithelium .
  The mesenchymal cells differentiate into cementoblasts and deposit a
  particular type of cementum, that is, afibrillar cementum, on enamel surface .

• 2) 30% of all teeth, cementum meets the cervical end of enamel in a knife
  edge-to-edge pattern .

• 3) In approximately 10% of teeth, cementum does not meet enamel where a
  zone of root dentin appears devoid of cementum . This can result in dental
  hypersensitivity as the gingiva recedes exposing the underlying root dentin
Relation of Cementum to Enamel at the Cementoenamel Junction (CEJ)




In 60% of the teeth cementum Overlaps enamel
In 30% of the teeth cementum just Meets enamel
In 10% of the teeth there is a small Gap between cementum and enamel
Edge to edge 30%

By/ Dr. Hesham
Dameer
Cementum do not meet enamel 10%

By/ Dr. Hesham
Dameer
Cementum overlaps enamel 60%

By/ Dr. Hesham
Dameer
Cementodentinal junction

The dentin surface upon
                                          Permanent teeth
    which cementum is
    deposited is relatively
    smooth in permanent
    teeth.
The cementodentinal junction
    in deciduous teeth,
    however, is sometimes
    scalloped.



      By/ Dr. Hesham           Deciduous teeth
      Dameer
Functions of cementum :
1. Cementum furnishes a medium for the incorporation of the
  principal periodontal fibers, thereby securing the binding of the
  tooth root to the alveolar bone proper .
2. Cementum 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 .
        By/ Dr. Hesham
        Dameer
Histological cross-section through a periodontal ligament . The periodontal
ligament fibers (F) originate from the cementum. and insert into bundle bone (BB),
so named because it contains numerous Sharpey's fibers (SF). Neurovascular
channels (NV) that house blood vessels, lymphatics and nerves in a loose
connective tissue sheath course throughout the periodontal ligament. The
ligament also contains cell rests of Malassez (M).
         By/ Dr. Hesham
         Dameer
Age changes of cementum
 1) Hypercementosis:
 It is an abnormal thickening of cementum, may be diffuse
       or circumscribed.
 It may affect all teeth of the dentition, be confined to a
       single tooth, or even affect only Parts of one tooth.
 If the overgrowth occurs in functional teeth and improves
       the functional qualities of the cementum, it is termed
       cementum hypertrophy.
 If the overgrowth occurs in nonfunctional teeth, it is
       termed cementum hyperplasia .
Hyperplastic cementum covering the enamel drops termed
excementosis
the enamel drops
Localized hypercementosis




                            Generalized hypercementosis
Age changes of cementum




  In Localized hypertrophy prong like
       extension of cementum may be
       formed. This condition
       frequently is found in teeth that
       are exposed to great stress
       (ortho) (compensatory
       cementum). This extension of
       cementum provide a larger
       surface area for the attaching
       fibers; thus a firmer anchorage
       of the tooth to the surrounding
       alveolar bone is assured.
Root resorption and
forming Reparatory
cementum
Root resorption – lost D. has been replaced by cellular
cementum, on the top of which acellular C. has formed
Hypercementosis




By/ Dr. Hesham
Dameer
2) Decrease permeability : by aging the permeability of
cementum decreses gradually , the permiability from the
periodontal ligament side is lost except in the most recent
formed layers of cementum .

3) Cementicles : they are ovoid or round calcified structure
that exhibits by dystrophic calcification of the degenerated
periodontal tissue or the epithelial rests of Malssez . They
nidus favoring the deposition of concentric layers of
calcosherites around the degenerated or hemorrhagetic
areas .
Cementicles may be:
 1. Free in the periodontal ligament.
 2. Attached the cementum and form excementosis.
 3. Embedded in the cementum during its growth by age.
Free Cementicles




                              Cementum


Bone




       Periodontal ligament
Periodontal ligament




Free Cementicles           Attached Cementicles
THE   My best wishes
         for you

END   Dr. HESHAM
          Dameer

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Cementum

  • 2. Cementum is part of the peridontium
  • 3. THE PERIODONTIUM The peridontium consists of those tissues which surrounds , support the tooth and is composed of : Gingiva Periodontal ligament Cementum Alveolar bone By/ Dr. Hesham Dameer
  • 4.
  • 5. Gingiva The gingiva is that part of the oral mucosa which surrounds the tooth and cover the alveolar bone . In light-skinned individuals the gingiva (G) can be readily distinguished from the adjacent dark red alveolar mucosa (AM) by its lighter pink color. Its apical border, that separates it from the adjacent alveolar mucosa, is the mucogingival junction (MGJ). A similar tissue relationship can be seen on the lingual aspect of the mandible
  • 6. AM, alveolar mucosa .G, gingiva .MGJ, mucogingival junction
  • 7. AM,alveolar mucosa .F, floor of the mouth .G, gingiva .MGJ, mucogingival junction
  • 8. Periodontal ligament Dense connective fibers that connect the cementum covering the root of the tooth with the alveolar bone of the socket wall . Principal fibers of the periodontal ligament : The periodontal fibers of the periodontal ligament are primarily composed of bundles of type I collagen fibrils. They have been classified into several groups on the basis of their anatomic location:
  • 9. The following constitute the principal fiber groups of the periodontal ligament: 1. Alveolar crest group 2. Horizontal group 3. Oblique group 4. Periapical group 5. Interradicular group By/ Dr. Hesham Dameer
  • 10.
  • 12. Cementum is a hard connective tissue that covers the root of the tooth to furnish a medium into which the principle fibers of the periodontal ligament are terminally inserted . By/ Dr. Hesham Dameer
  • 13. Cementum It begins at the cervical portion of the tooth at the cemento- enamel junction and continues to the apex. Cementum furnishes a medium for the attachment of collagen fibers that bind the tooth to surrounding structures. By/ Dr. Hesham Dameer
  • 14. Physical Characteristics 1-Color Light yellow Lighter in color than dentin 2- Thickness Acellular cementum (20-50 m) Cellular cementum (150-200 m) 3- Permeability Permeable from dentin and PDL sides. Cellular C is more permeable than acellular C.
  • 15. Chemical Composition 45-50 % Inorganic 50-55% Organic substances substances collagen consists of fibers protein calcium phosphate in the embedded form of hydroxy- in a ground apatite crystals substance . Polysaccharides Cementum contains the greatest amount of fluoride in all mineralized tissues By/ Dr. Hesham Dameer
  • 16. Cementogenesis • 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
  • 17. Cementogenesis Cementum formation in the developing tooth is preceded by the deposition of dentin along the inner aspect of Hertwig‘s sheath . Once dentin formation is underway breaks occur in the epithelial root sheath allowing the newly formed dentin to come in direct contact with the connective tissue of the dental sac , the undifferentiated mesenchymal cells derived from the dental sac differentiate into cementoblasts . These cells have the ultrastructural characteristics typical of cells actively synthesis protein and polysaccharide . The main product of cementoblasts is collagen and ground substances , both constitute the organic component of cementum . The inorganic material of cementum is calcium phosphate Hydroxy apatite .
  • 18. Cementogenesis After degeneration of the epithelial root sheath ectomesenchymal cells from the inner portion of the dental Odontoblast follicle differentiate and become cementoblasts cementoblasts. By/ Dr. Hesham Dameer
  • 19.
  • 20.
  • 21.
  • 22. Growth of cementum is a rhythmic process and as a new cementoid is formed, the old one is calcified . A thin layer of cementoid can be observed on cemental surface which is covered by cementoblasts . The mineralization begins after forming the first layer of matrix. The mineral crystals is deposited within and between the collagen fibers, the long axes of the crystals are arranged parallel to the long axis of the collagen fibers . Sometimes crystals can be seen clustered into groups of nucleation centers as found in bone.
  • 23. Cementogenesis cementoid Cementodentinal junction Cementoblasts
  • 24. Cementoblast is a protein forming and secreting cell. Maturation occur layer Collagen fibers + by layer for the ground substance. collagen fibers D Cementum Large open face nucleus Cementoblasts Cementoblast RER Cementoid layer Golgi apparatus Mitochondria Secretory granules Alkaline phosphatase
  • 25. Cementogenesis After reaching the full thickness the cementoblasts enter a quiescent stage. During matrix formation fibroblasts form collagen fibers (sharpey`s fibers), which become embedded in the matrix to provide attachment of the root to the surrounding bone. Those fibers are also called perforating fibers. . By/ Dr. Hesham Dameer
  • 26.
  • 27. Remnants of the Hertwig`s root sheath, which disintegrate into the PDL are the Malassez cells. intermediate cementum By/ Dr. Hesham Dameer
  • 28. Histological structure : cementum cover the root dentin from cementoenamel junction to the root apex . It is thinnest at this junction ( 20 – 50 μm ) but becomes gradually thicker apicalward ranging from 150 – 200 μm ) or more . By/ Dr. Hesham Dameer
  • 29. Two forms of collagen are found in cementum : * collagen fibrils * collagen bundles The collagen fibrils are arranged in a very complex fashion and constitute the main bulk of the organic material of cementum. The collagen bundles represent the embedded portion of the principle fibers of the periodontal ligament, that is Sharpey s fibers .
  • 30. Two types of cells are functionally concerned with cementum : * Cementoblasts * Cementocytes Cementoblasts line the root surface and when active, they contain numerous mitochondria, well developed Golgi complex, and open-faced nucleus. However, in resting cementoblasts, these cytologic features become less pronounced . By/ Dr. Hesham Dameer
  • 31. While cementum is being deposited, cementoblasts retreat leaving behind the formed cementum matrix. Occasionally, however, cementoblasts become entrapped in the forming matrix and then known cementocytes .
  • 32. Cementocytes are seen located in lacunae in cementum matrix and typically have numerous processes lying in canaliculi . These processes may branch and frequently anastomose with those of the adjacent cementocytes . This indicates that these cells are not functionally separated from each other . Because cementum is avascular tissue, thus the processes of the cementocytes are oriented toward the periodontal ligament for nutrition . As a result of continuous phasic deposition of cementum, resting lines known Salter lines appear in cementum . By/ Dr. Hesham Dameer
  • 35.
  • 36. Cementocyte canaliculi Cementocyte Cementocyte process
  • 37.
  • 38. Incremental Lines • Incremental lines of Salter. Incremental lines of Salter
  • 39. Incremental lines of Salter Dentin
  • 41. Types of cementum : I) Based on cellular connotation : 1- Cementum containing cells : a. Cellular cementum b. Intermediate cementum 2- Acellular cementum II) Based on fibrillar connotation : 1. Intrinsic fibers cementum 2. Extrinsic fibers cementum 3. Mixed fibers cementum 4. Afibrillar cementum
  • 42. I) Based on cellular connotation : 1- Cementum containing cells : a. Cellular cementum is more frequently found on the apical half of the root where cementum does contain cementocytes in its matrix . b. Intermediate cementum Intermediate cementum is a thin, amorphous layer of hard tissue approximately 10 micron thick. Is more frequently seen in the apical two thirds of the roots of posterior teeth but rarely in incisors or primary teeth . This type of cementum does not exhibit the characteristic features of either dentin or cementum, while in regard to its location, it is found intermediate between cementum and dentin .
  • 43. In respect to the involved cells observed in intermediate cementum, there is argument about there derivation : 1- The cells of the epithelial root sheath of Hertwig are proposed to become entrapped while dentin or cementum is being rapidly deposited . 2- Other concept claims that odontoblasts are trapped on the outer dentin surface at the commencement of dentinogenesis which subsequently being enclosed by the forming cementum .
  • 45. Remnants of the Hertwig`s root sheath, which disintegrate into the PDL are the Malassez cells. intermediate cementum By/ Dr. Hesham Dameer
  • 46. 2- Acellular cementum : The matrix of this type of cementum does not involve cementocytes . However, cementoblasts present on its outer surface and constitute an integral component of acellular cementum . Acellular cementum may cover the root dentin from the cementoenamel junction to the root apex, but with frequent absence on the apical third of the root . II) Based on fibrillar connotation : 1. Intrinsic fibers cementum : the fibers are derived from the synthetic and secretory activity of cementoblasts .
  • 47. 2. extrinsic fibers cementum : in this form, the extrinsic fibers originate from the principal fibers of the periodontal ligament that is Sharpey s fibers . 3. mixed fibers cementum : it contains both intrinsic and extrinsic fibers . 4. Afibrillar cementum : as enamel is completely formed and become fully calcified, it is seen covered by the reduced enamel epithelium which is of paramount importance in protecting enamel, however, the reduced enamel epithelium may retract from the cervical region of enamel . This allows for the adjacent mesenchymal cells to invade and intervene between enamel and its covering epithelium . The mesenchymal cells differentiate into cementoblasts and deposit a particular type of cementum, that is, afibrillar cementum, on enamel surface . By/ Dr. Hesham Dameer
  • 48. Cementoenamel Junction (CEJ) • 3 patterns may be present • 1) In approximately 60% of teeth cementum overlapping the cervical end of enamel for a very narrow area at the CEJ . This occurs as a result of premature degeneration or retraction of the reduced enamel epithelium at the cervical region of enamel . This allows for the adjacent mesenchymal cells to invade and intervene between enamel and its covering epithelium . The mesenchymal cells differentiate into cementoblasts and deposit a particular type of cementum, that is, afibrillar cementum, on enamel surface . • 2) 30% of all teeth, cementum meets the cervical end of enamel in a knife edge-to-edge pattern . • 3) In approximately 10% of teeth, cementum does not meet enamel where a zone of root dentin appears devoid of cementum . This can result in dental hypersensitivity as the gingiva recedes exposing the underlying root dentin
  • 49. Relation of Cementum to Enamel at the Cementoenamel Junction (CEJ) In 60% of the teeth cementum Overlaps enamel In 30% of the teeth cementum just Meets enamel In 10% of the teeth there is a small Gap between cementum and enamel
  • 50. Edge to edge 30% By/ Dr. Hesham Dameer
  • 51. Cementum do not meet enamel 10% By/ Dr. Hesham Dameer
  • 52. Cementum overlaps enamel 60% By/ Dr. Hesham Dameer
  • 53. Cementodentinal junction The dentin surface upon Permanent teeth which cementum is deposited is relatively smooth in permanent teeth. The cementodentinal junction in deciduous teeth, however, is sometimes scalloped. By/ Dr. Hesham Deciduous teeth Dameer
  • 54. Functions of cementum : 1. Cementum furnishes a medium for the incorporation of the principal periodontal fibers, thereby securing the binding of the tooth root to the alveolar bone proper . 2. Cementum 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 . By/ Dr. Hesham Dameer
  • 55. Histological cross-section through a periodontal ligament . The periodontal ligament fibers (F) originate from the cementum. and insert into bundle bone (BB), so named because it contains numerous Sharpey's fibers (SF). Neurovascular channels (NV) that house blood vessels, lymphatics and nerves in a loose connective tissue sheath course throughout the periodontal ligament. The ligament also contains cell rests of Malassez (M). By/ Dr. Hesham Dameer
  • 56. Age changes of cementum 1) Hypercementosis: It is an abnormal thickening of cementum, may be diffuse or circumscribed. It may affect all teeth of the dentition, be confined to a single tooth, or even affect only Parts of one tooth. If the overgrowth occurs in functional teeth and improves the functional qualities of the cementum, it is termed cementum hypertrophy. If the overgrowth occurs in nonfunctional teeth, it is termed cementum hyperplasia . Hyperplastic cementum covering the enamel drops termed excementosis
  • 58. Localized hypercementosis Generalized hypercementosis
  • 59. Age changes of cementum In Localized hypertrophy prong like extension of cementum may be formed. This condition frequently is found in teeth that are exposed to great stress (ortho) (compensatory cementum). This extension of cementum provide a larger surface area for the attaching fibers; thus a firmer anchorage of the tooth to the surrounding alveolar bone is assured.
  • 60. Root resorption and forming Reparatory cementum
  • 61. Root resorption – lost D. has been replaced by cellular cementum, on the top of which acellular C. has formed
  • 63. 2) Decrease permeability : by aging the permeability of cementum decreses gradually , the permiability from the periodontal ligament side is lost except in the most recent formed layers of cementum . 3) Cementicles : they are ovoid or round calcified structure that exhibits by dystrophic calcification of the degenerated periodontal tissue or the epithelial rests of Malssez . They nidus favoring the deposition of concentric layers of calcosherites around the degenerated or hemorrhagetic areas . Cementicles may be: 1. Free in the periodontal ligament. 2. Attached the cementum and form excementosis. 3. Embedded in the cementum during its growth by age.
  • 64. Free Cementicles Cementum Bone Periodontal ligament
  • 66.
  • 67. THE My best wishes for you END Dr. HESHAM Dameer