2. CONTENTS
INTRODUCTION
DEVELOPMENT
TYPES OF CEMENTUM
STRUCURE AND COMPOSITION
ACELLULAR AND CELLULAR CEMENTUM
CEMENTOENAMEL JUNCTION
DENTINOCEMENTAL JUCNTION
PATHOLOGY
ANKYLOSIS
CEMENTUM RESORPTION
3. CEMENTUM
CEMENTUM
is defined as
calcified avascular
mesenchymal tissue that forms
the outer covering of root.
The cementum is the part of
the periodontium that attaches
the teeth to the alveolar bone
by anchoring the periodontal
ligament.
4.
5.
6.
7. DEVELOPMENT OF CEMENTUM
Cementoid is excreted by cells
called cementoblasts within the
root of the tooth and is thickest at
the root apex.
These cementoblasts develop
from undifferentiated
mesenchymal cells in the
connective tissue of the dental sac
or follicle.
During the later steps within the
stage of apposition, many of the
cementoblasts become entrapped
by the cementum they produce,
becoming cementocytes.
9. STRUCTURE AND COMPOSITION:
Both acellular and cellular cementum consists of:
1.CALCIFIED INTERFIBRILLAR MATRIX
2.COLLAGEN FIBRES
The two main sources of collagen fibers in cementum are:
1.EXTRINSIC or SHARPEY’s FIBRES
2.INTRISIC FIBRES
Sharpey’s fibres are embedded portion of principle fibers' of
periodontal ligament and are formed by fibroblasts.
10. ACELLULAR
CEMENTUM
It is the first formed cementum.
It does not contain cells and
covers approx. cervical third or
half of the root.
Formed before the tooth
reaches the occlusal plane.
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.
CELLULAR
CEMENTUM
It is formed after the
tooth reaches the
occlusal plane, is more
irregular and contain
cells called
cementocytes in
lacunae.
Cellular cementum is
less calcified than
acellular cementum.
Sharpey’s fibres
occupy a smaller
portion and may be
less calcified.
11.
12. CEMENTOENAMEL
JUNCTION
The cementum joins the enamel to
form the cementoenamel junction
(CEJ), which is referred to as
the cervical line.
Three possible types of
transitional interfaces may be
present at the CEJ.
In about 60-65% of cases
cementum overlaps enamel, in
about 30% of cases edge to edge
butt joint exists and in about 510% of cases cementum and
enamel fail to meet.
13.
14. DENTINOCEMENTAL
JUNCTION
When the cementoid reaches the full thickness
needed, the cementoid surrounding the
cementocytes becomes mineralized, or matured,
and is then considered cementum.
Because of the apposition of cementum over the
dentin, the dentinocemental junction (DCJ) is
formed.
This interface is not as defined, either clinically or
histological, as that of the dentinoenamel junction.
The dentinocemental junction (DCJ) is a relatively
smooth area in the permanent tooth, and
attachment of cementum to the dentin is firm.
16. PATHOLOGY
HYPERCEMENTOSIS:The
excessive build up of
cementum on the roots of a
tooth is a pathological
condition known
as hypercementosis
Cementum thickness can
increase on the root end to
compensate for attritional wear
of the occlusal/ incisal surface
and passive eruption
of the tooth.
When cementum is exposed
through gingival recession,
it quickly undergoes abrasion
by mechanical friction
because of its low
mineral content and thinness..
17. The incidence of cemental caries increases in older adults as gingival recession
occurs from either trauma or periodontal disease. Cementicles are
mineralized bodies of cementum found either attached to the cemental root
surface or lying free in the periodontal ligament.
18. ANKYLOSIS
The fusion of cementum and alveolar bone with
obliteration of periodontal ligament is known as
ankylosis.
Ankylosis occurs in teeth with cemental resorption.
It results in resorption of root and its replacement by
bone tissue.
Resorption lacunae are filled with fluid.
It may develop after occlusal trauma.
19.
20.
21. CEMENTUM
RESORPTION:
Permanent teeth do not undergo resorption as do the
primary teeth.
Causes: Trauma from occlusion, orthodontic
movement, periapical disease, cysts and tumors.
It is painless.
