seminar presentation on cementum and its differnt types,functions,age changes,future advancements at the level of undergraduates

1. Submitted
by
Ajo Babu
Geoge

2.  Introduction
 Physical Characteristics
 Chemical Composition
 Cementogenesis
 Structure and Classification
 Intermediate Cementum
 Cementoenamel Junction
 Cementodentinal Junction
 Functions
 Hypercementosis
 Ankylosis
 Clinical Considerations
 References

3.  Cementum is a calcified , avascular mesenchymal
tissue forming the outer covering of the anatomic
root.
 Begins at the cervical portion of the tooth at CEJ and
continues to the apex
 Avascular and non- innervated.
 Furnishes a medium for attachment of that help to
bind the root to surrounding alveolar bone.

4.  COLOUR: Yellow,lighter than dentin but darker than
enamel (darker hue and lacks lustre)
 HARDNESS: Lesser than dentin, more resilent,
 PERMEABILITY: Permeable to inorganic ions,bacteria;
which diminishes with age ;cellular cementum is more
permeable than compared to acellular cementum
 THICKNESS:
-Coronal half of root-16-60microns
- apical third & furcation areas-150-200microns
-An average thickness of 95microns (20yrs) and
215microns (65 yrs)

5. Organic components
 Calcium and phosphorus in
the form of hydroxyapatite
crystals.
 Fluoride ( highest
concentration)
 Trace metals-Mg,Zn
Inorganic components
 Type I collagen in addition
to types III,V,VI,XII
 Protein polysaccharides-
proteoglycans
 Non-collagenous protein
BSP,CAP,osteopontin
,Chondroitin
sulfate,heparin sulfate,etc

6.  Formation of cementoblasts-differentiation occurs when
cells of dental follicle comes in contact with newly formed
dentin
 Organic matrix-collagen and protein polysaccharides-the
collagen fibrils (cementoblasts) forms a fibrous fringe
perpendicular to periodontal space,incremental lines of Salter.
 Mineralization –cementoid ( uncalcified matrix),Ca and P ions
are deposited as units of hydroxyapatite
-Gla protein –osteocalcin ,osteonectin-nucleators
-BSP,alkaline phosphatase-promotes mineralization
-Osteopontin,lumican,fibromodulin,insulin like growth
factor- -regulates growth of crystals
 Cementoid –Sharpey’s fibers

7. Incremental
lines of salter

8. Schroeder’s classification
 Acellular afibrillar cementum- contains neither cells
nor extrinsic (sharpey’s) or intrinsic collagen
,product of cementoblasts,found as coronal
cementum -1 to 15microns
 Acellular extrinsic fiber cementum-densely packed
bundles of sharpey’s fibers,lacks cells,product of
cementoblasts & fibroblasts,found in cervical third
of roots-30-230microns

9. Acellular extrinsic
fiber cementum
Incermental
lines of
Salter

10.  Cellular mixed stratified cementum- contain extrinsic
(sharpey’s ),intrinsic and cells,co-product of fibroblasts &
cementoblasts,found in apical third,furcations & apices-
100 to 1000microns
 Cellular intrinsic cementum –contain cells,no extrinsic
collagen fibers,formed by cementoblasts,fills resorption
lacunae
 Intermediate cementum –poorly defined zone near
CEJ,contain cellular remnants of HERS in calcified ground
subtance

11. cementocytes
dentin

12.  Structureless-apical 2/3rd of roots of roots of molars and
premolars –hyaline layer
 Represent areas where cells of HERS become trapped in
rapidly forming dentin or cementum matrix
 Dentinal origin-contain wide spaces –enlarged terminals
of dentinal tubules
 Amorphous layer of non collagenous material devoid of
odontoblasts and cementoblasts
 First described by Bodecker(1878)-interzonal layer
 Hopewell –Smith (1920),homogenous layer between
Tomes granular layer and cementum

13. intermediate
cementum separates
dentin from
cementum , but
doesn’t exhibit the
characteristics of
dentin and
cementum

14. Three types of relationships between cementum and
enamel is seen broadly-
1. Cementum overlapping enamel-60-65%
2. Edge to edge ,butt joints-30%
3. Cementum fails to meet enamel-5-10%
Recent observations by optical microscopy showed presence of a
fourth type of junction –enamel overlapping the cementum

15. a)Cementum overlapping enamel type
b)Edge to edge CEJ
c) Gap type CEJ
d)Enamel overlapping cementem type

16. Though different functions are attributed to the different
types of cementum it functions as a single unit
1. Anchorage-furnishes a medium for attachment of
collagen fibers to bind roots to alveolar bone
2. Adaptation-deposition of cementum in apical region
can compensate for loss of tooth substance dueto
occlusal wear ( attrition)
3. Repair – damages to root (fractures resorptions )can be
repaired by deposition of new cementum

17.  The terminal apical area of the cementum where it joins
the internal root canal dentin- dentinal surface upon
which cementum is deposited
 CDJ - relatively smooth in permanent teeth
-scalloped in deciduous teeth
 Wide zone containing large quantities of collagen
associated with glycosaminoglycans like chondroitin
sulfate and dermatin sulfate .
 Cemental fibers intermingle with the dentinal fibers more
in case of cellular cementum than in acellular cementum
at CDJ- attachment

18. cementocytes
dentin

19.  Abnormal thickening of cementum-diffuse or circumscribed : age
related phenomenon- 200-215 microns with progressing age.
 Generalized thickening-nodular enlargement of apical third of the
root.-Paget’s disease,rheumatic fever.
 Localized hypercementosis-formation of spur/pong like
extensions,around enamel drops-benign cementoblastoma, florid
cemento-osseous dysplasia,acromegaly,calcinosis,arthritis.
 Cemental spikes created either by coalescence of cementacles that
adhere to the root or the calcification of PDL at sites of insertion.
 Radiographically –radiolucent PDL space and radiopaque lamina
dura seen as outer border of hypercementosis.
 Doesn’t require treatment but poses problems during extraction.
 Hypoplasia /aplasia of cementum is rare-hypophosphatasia.

20. HYPERCEMENTOSIS
Generalised

21. Cementacles- Calcified oval or round nodules found in the PDL,
single or in groups.
 The origin may be calcified epithelial Cells (Rests of Malassez)
 They may be free or attached or embedded in cementum.
They act as 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 to the cementum and form excementosis.
3. Embedded in the cementum during its growth by age.

22. cementacles
cementum
bone
PDL

23.  Fusion of cementum with alveolar bone with obliteration of
the PDL
 Represent abnormal repairs, develops after chronic periapical
inflammation ,occlusal trauma ,implants etc
 Radiographically –resorption lacunae are filled with bone and
periodontal space is absent
 Clinically-absence of physiological mobility of normal tooth,
exhibits metallic percussion, infraocclusion (process
continues)
 Formation of true periodontal pocket due to lack of apical
proliferation of epithelium around root.
 Titanium implants-direct bone apposition without intervening
connective tissue

24. Infraocclusally placed tooth due
to ankylosis
Zirconia based dental implant following
ankylosis

25.  Orthodontic treatment- cementum is more resistant to resorption
than bone –migration of tooth occurs
 Cementum resorption occurs in case of extensive occlusal forces
/trauma- leads to functional /anatomical repairs
 Transverse fractures of root are healed following trauma.
 Small fragments of roots left in sockets following extractions are
surrounded by cementum –causing no trouble
 Cementum becomes exposed to oral environment ( gingival
recession & pocket formation)
 Bacterial invasion results-formation of hyper mineralized (
Ca,F,P),decrease in cross striations of collagen: lipopolysaccharides
confined to surface
 Cemental caries can be seen on exposed surfaces of cementum with
gingival recession in older individuals

26. Cemental caries
following gingival
recession in older
patients
Exposed cementum-gingival recession leading
to calculus and plaque accumulation
Orthodontic treatment

27.  Cementum is an avascular mineralized tissue covering the entire
root surface. Due to its intermediary position, forming the
interface between root dentin and periodontal ligament,
cementum is a component of the tooth itself, but belongs
functionally to the dental attachment apparatus, that is, the
periodontium.
 One of the main functions of cementum is to anchor the principal
collagen fibers of the periodontal ligament to the root surface, but
it also has important adaptative and reparative functions, playing a
crucial role to maintain occlusal relationship and to protect the
integrity of the root surface.
 Dental cementum is unique in various aspects: it is avascular and
not innervated, does not undergo continuous remodelling like
bone, but continues to grow in thickness throughout life.

28.  In contrast with these specific histological characteristics, it
appears not to be specific at the cellular and molecular level.
Unlike dentine and enamel, where there are clear differences in
the proteins present in these tissues and the factors regulating
their functions when compared with bone, cementum has not
demonstrated to express specific proteins, appearing to contain
factors in common with bone and to be developmentally
controlled by similar factors
 RESEARCH AND DEVELOPMENTS: The relationship between
osteoblasts and cementoblasts, provides more information
regarding the specific mechanisms involved in maintenance of
cementum structure and function in humans on the cellular and
molecular level. Similarly, the in vitro/in vivo system can also be
used for further elucidation of the modes of action of current
available regenerative products, such as Emdogain, with apparent
cementum-growth-promoting activities.

29.  Orban’s Oral Histology and Embryology (11th Ed)—GS
Kumar
 Carranza’s Clinical Periodontology-(11th Ed)-
Newman,Taki,Carranza
 Textbook of Oral Histology (6th Ed)- Tencates’s
 Textbook of Oral Pathology(7th Ed)- Shafer,Hine.Levy