The document discusses the structure and function of cementum, a calcified tissue covering the tooth root, detailing its formation, cellular components, and structural variations such as acellular and cellular cementum. It highlights the importance of cementum in tooth attachment, adaptability, repair, and various conditions affecting its health, including hypercementosis and resorption. The document concludes with the implications for restorative dentistry, emphasizing the need for an understanding of cementum's properties in treatment planning.

1. Presented by-
Dr. Anushri Gupta
PG first year
Department of Periodontology

2.  Cementum is the calcified, avascular
mesenchymal tissue that forms the outer
covering of the anatomic root.

3.  The rupture of Hertwig root sheath allows the
mesenchymal cells of the dental follicle to contact
the dentin where they start forming a continuous
layer of cementoblast.
 Cementum formation begins with the deposition of
a meshwork of irregularly arranged collagen fibrils
sparsely distributed in a ground substance of matrix
called precementum or cementoid

4.  This is followed by a phase of matrix maturation,
which subsequently mineralizes to form a
cementum.
 Cementoblasts, which are initially separated from
the cementum by uncalcified cementoid, sometimes
become enclosed within the matrix and are trapped.
After they are enclosed they are called cementocytes.

6.  The two main source of collagen fibers in cementum
are
 Sharpey fibers (extrinsic), which are the embedded
portion of the principal fibers of the periodontal
ligament and which are formed by the fibroblasts,
 fibers that belong to the cementum matrix
(intrinsic), which are produced by the
cementoblasts .

8.  Inorganic : 45-50%, mainly hydroxy-apatite crystals.
 Organic: 50-55%, mainly Type I collagen (90%) and type III
(About 5%)
 Non collagenous proteins like
polysaccharides (prteoglycans),
alkaline phosphatase
bone sialoprotein
fibronectin
osteocalcin
proteolipids
osteopoetin and several growth factors

9.  Based on –
A. Location.
B. Presence or absence of cells.
C. Origin of collagenous fibers of the matrix.
D. According to schoreder.

10. A. Location –
1. Radicular cementum:
 It is the derivative of dental follicle, proper covers the entire
dentin of the root fromCEJ to the apex. It extends partially
into apical foramen to line the apical walls of the root canal.
2. Coronal cmentum:
 In humans, it is restricted to areas of reduced enamel
epithelium.

11. B. Presence or absence
of cells-
 Acellular cementum
(primary)
 It is first formed
cementum.
 Formed before the tooth
reaches the occlusal
plane
 It does not contains cells
and covers approx.
cervical third or half of
the root.
 Cellular cementum
(secondary)
 It is formed after the
tooth reaches the
occlusal plane.
 It is more irregular and
contains cells called
cementocytes in lacunae.
 less calcified than
acellular cementum.

12.  Thickness : 30-230
micrometers.
 Sharpey’s fibers make
up most of the
structure of acellular
cementum and play a
principle role in
supporting the tooth.
 Sharpey’s fibers
occupy a smaller
portion and may be
less calcified.

13. C. Based on origin of
collagenous fibers-
 Intrinsic fibre
cementum:
 Cementoblast secretes
collagen fibres and ground
substance.
 These fibres are parallel to
root surface and do not
extend into PDL.
 Extrinsic fibre
cementum:
 When PDL fibres get
attached to fibrous fringe
of acellular cemenum, it is
k/a Sharpey’s fibers.
 In permanent teeth,
attachment occurs after
teeth has erupted in oral
cavity.

14.  Acellular afibrillar cementum (AAC)-
 contains neither cells nor extrinsic or intrinsic
collagen fibers, except for a mineralized ground
substance.
 Acellular afibrillar cementum is a product of
cementoblasts and found as coronal cementum in
humans, with a thickness of 1-15µm.

15.  Acellular extrinsic fiber cementum (AEFC)-
 It is composed entirely of densely packed bundles of
sharpey fibers and lack cells.
 Acellular extrinsic fiber cementum is a product of
fibroblasts and cementoblasts .
 It is found in the cervical third of roots in humans,
but it may extend farther apically.
 Its thickness is between 30 and 230µm.

16.  Cellular mixed stratified cementum (CMSC)-
 It is composed of extrinsic (sharpey) and intrinsic
fibers, and it may contain cells.
 It is a co-product of fibroblasts and cementoblasts.
 In humans, it appears primarily in the apical third of
the roots and in furcation areas.
 Its thickness ranges from 100 to 1000 µm.

17.  Cellular intrinsic fiber cementum (CIFC)-
 Contains cells but no extrinsic collagen fibers.
 It is formed from cementoblast.
 In human it fills the resorption lacunae.(small
concavities on the root surface)

19.  It is poorly defined zone near the cementodentinal junction
of certain teeth that appers to contain cellular remnants of
the Hertwig’s sheath embedded in calcified ground
substance.
 Generally present apical third region as a continuous layer or
sometimes found in isolated areas.

20.  It is the relation between the enamel and
cementum edges at the cervix of the tooth.
 Three types of relationships involving the
cementum may exist at the cementoenamel
junction-
 60-65% cementum overlaps enamel.
 30% edge to edge butt joint.
 5-10% cementum and enamel fail to meet.

21. Three configurations of the cementoenamel junction in ground sections.
A, Cementum overlaps the enamel. B, A deficiency of cementum
(bracket) leaves root dentin exposed. C, A butt joint is visible (arrow).

22.  The terminal apical area of the cementum
where it joins the internal root canal dentin
is known as cementodentinal junction.
 When root canal treatment is performed, the
obturating material should be at the
cementodentinal junction.
 There is no increase or decrease in the width of the
cementodentinal junction with age.
 cementodentinal junction is 2-3µm wide.

23.  Cementum formation is most rapid in apical
regions where it compensates for tooth
eruption.
 The thickness of cementum on the coronal
half of the root varies from 16-60µm.
 Greatest thickness (≤150 - 200µm) in the
apical third and in the furcation area.
 Thicker in distal surface than in mesial
surface.

24.  Between the age of 11 and 70 years, the
average thickness of cementum increases.
 Average thickness of 95µm at the age of 20
yrs and 215µm at the age of 60 yrs.

25.  ANCHORAGE
 Cementum serves as a medium for the attachment of collagen
fibers that bind the tooth to alveolar bone
 ADAPTATION
 Continuous Deposition of cementum in apical area compensates for
loss of tooth substance from occlusal wear.
 This process also serves to maintain the width of the periodontal
ligament space at the apex of the root.

26.  REPAIR
 Major reparative tissue for root surfaces in case of
fractures and resorptions.
 In this process cellular cementum is formed.
 It repair of root fractures, Seals off necrotic pulps
(apical occlusion) protection of the subjacent dentinal
tubules.
 Cementogenic activity contributes to periodontal
ligament fiber reattachment and relocation that occurs
as a consequence of mesial drifting of teeth

27.  Abnormal thickening of cementum with nodular
enlargement of the apical third of the root.
 May be localized to one tooth or affect the entire
dentition.
 It also appears in the form of
spikelike growth.
 The spikelike type of
hypercementosis generally results
from excessive tension caused
by orthodontic appliances or occlusal forces.

28.  Hypercementosis of the entire dentition may
occur in patients with paget disease.
 Other systemic disturbances that may lead to
or may associated with hypercementosis
include acromegaly, arthritis, calcinosis,
rheumatic fever and thyroid goiter.

29.  Permanent teeth do not undergo physiologic
resorption as primary teeth do.
 Cementum resorption may be caused by local or
systemic factors.
 Local condition –
 trauma from occlusion
 orthodontic movement
 pressure from malaligned erupting teeth.
 Cyst and tumors.

30.  Embedded teeth
 Replanted and transplanted teeth
 Periapical disease
 Periodontal disease
 Systemic condition-
 Calcium deficiency
 Hypothyroidism
 Hereditary fibrous osteodystrophy
 Paget disease

31.  Cementum resorption appears microscopically as
baylike concavities in the root surface.
 Multinucleated giant cells and large mononuclear
macrophages are generally found adjacent to the
cementum that is undergoing active resorption.
 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 deeply staining irregular line termed as
reversal lines.

32.  Cementum grows appositionally throughout life at a linear rate,
although the variations in width of incremental lines indicate that
the rate of cementum deposition varies from period to period.
 Generally, cementum increases in thickness by different growth
patterns among types of cementum being formed.
 Its thickness varies greatly with tooth group, tooth surface area,
and cervical/apical root positions.

33.  Cementum, like bone, is a dynamic tissue, capable of
responding to occlusal forces and physiological tooth
movement.
 The greatest amount of cementum is deposited apically,
constricting the apical foramen, and in the furcations of
multi-rooted teeth.
 According to Schroeder , cementum is thicker in areas
exposed to tensional forces, whereas Dastmalchi et al.
found that cementum thickness is increased more rapidly at
the distal than the mesial parts of root surface.

34.  Fusion of cementum and alveolar bone with
obliteration of periodontal ligament.
 Ankylosis occurs when partial root resorption is
followed by repair with either cementum or dentin that
unites the tooth root with the alveolar bone, usually
after trauma.
 It occur due to-
 Cemental resorption
 Chronic periapical inflammation
 Tooth replantation
 Occlusal trauma

35.  Ankylosis results in the resorption of the root and its
gradual replacement by bone tissue.
 Clinically ankylosed teeth lack the physiologic
mobility of normal teeth, which is one diagnostic
sign for ankylotic resorption.

36.  Exposure of cementum to the oral environment in
cases of
 gingival recession and
 as a result of the loss of attachment in the pocket
formation.
 Cariogenic plaque, rather than periodontitis or
gingival inflammation, is the essential factor
responsible for root caries development.

37.  The different forms of root surface caries, ranging from
minor undemineralized and discolored areas to extensive
yellow-brown soft areas, are rarely associated with
cavitation below the affected cementum.
 Active root surface lesion presents a well-defined area of
softening and yellowish discoloration while Inactive root
surface lesion appears hard on probing with dark
discoloration.

38.  As the patterns of oral disease continue to evolve,
restorative strategies in future research will include the root-
calcified tissue system.
 A complete understanding of tissue microstructure and
chemical composition and the basic reaction patterns of root
dentin and cementum to restorative techniques and
materials must be pursued.
 It always must be remembered that the cervical margin of
restorations located below the cemento-enamel junction is
primarily an area of vital tissue therapy.

39. THANK YOU