Cementum

CEMENTUM

Republic of YemenFaculty of dentistry

Department of conserveFeb 2012

Cementum is a very thin , avascular and calcified layer of tissue that covers the surface of the root of the tooth and

ensures the cohesion with the alveolar bone. It is produced by cells called cementoblasts, and is softer and less

mineralized than enamel and dentin.

Cementum

Cementum

*One of four tissues supporting the tooth

(periodontium)*The least known

of: -Periodontium

tissues. -All mineralized

tissues.

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 roleto maintain occlusal relationship and to

protect the integrity of the root surface.

The Properties of cementum

Physical properties

-Pale yellow-Softer than dentine

-PermeabilityVaries with age and type of cementumDecreases with ageCellular is more permeableMore permeable than dentine

-Readily removed by abrasion after gingival recession

Composition1 -hydroxapatite.

2 -collagen fiber type 23 -protien polysaccarride

4 -water

The origin of cementum

What is the (HERS)?Hertwig’s epithelial root sheat (HERS):

2 layers extension of reduced enamel epitheliumthat proliferate apically from cervical loop

A. Enamel organ

B. Dental papillaC. Dental follicle

The cementogensis

1 _disintegration of HERS(fragmentation)

2 -Cementum and cementum matrix.

3 -Cementoid (Precementum)

The classification of cementum

According to the locationRadicular

cementum

Coronal cementu

mThe cementum which is found on root surface.

The cementum which is found on enamel covering the root

crown .

A-Cornal CementumC- radicular cementum

According to cells

The classification of cementum

Cellular cementum(pri

mary)

Acellular cementum(seco

ndary)The cementum containing

cementoblasts found in champers called lacuna

within cementum matrix and found at

apical third of root .

Cementum without any cells within matrix and found at cervical third

of roots

The classification of cementum According to

presence of collagen fibrilFibrillar

cementumAfibrillar

cementumThe cementum with

matrix contain defined type 1 collagen fibrils

Cementum with matrix devoid detectable type

1 collagen fibrils.

The classification of cementum

According to origin matrix fiberExtrinsic

fiber cementum

(from fibroblast)The cementum

contain Sherpey's fibers which

extrinsic surface and play role in tooth anchorage

Intrinsic fiber

cementum (form

cementoblast) Cementum contain

intrinsic fibers produced by

cementoblasts and play no role in

tooth anchorage

Mixed fiber cementum

Cementum contain

mixture of extrinsic

and intrinsic

fiber cementum

1-Hypercementosis:is abnormally prominent thickness of cementum root.

Types:

1 -local: Occur in single tooth.eg:cemental spikes ; exocementosis

2 -Generalized:Occur in roots of all the teeth.Causes:

-Paget disease bone [hereditary].-chronic periapical infection.

The cemental anomalies

Radiographic appearance of maxillary posterior teeth with evidence of hypercementosis.

HC, hypercementosis

 Hypercementosis (HC) refers to abnormally large cellular cementum deposits on the apical third of one or

more teeth.

The cemental anomalies

2 -Hypocementosis:Hypoplasia or Aplasia , It is lack of cellular cementum following the deposition of cellular cementum.

3 -Cementicals:Round cemental bodies found free in periodontal ligament or adherent to the root surface.Cause:

-In aging person .-Trauma .

Histologic section through a free and a sessile cementicle.

C, root cementumFC, free

cementiclePDL, periodontal

ligamentSC, sessile cementicle

Scanning electron 

micrograph of root surface

with numerous 

sessile cementicle

s.

Imbedded cementicle

within a thick layer

of cementum.Legends:

AEFC, acellular, extrinsic

fiber cementumCTC, imbed

ded cementicle

The cemental anomalies

4 -Cementoma:Synonyms: benign cementoblastoma or cemental dysplasia.Occurs: in apex of root . Mostly mandibular first molar, in female more that male(under age 25).Structure: cementoblasts surround by C.T capsule

THE CEMENTUM RESORPTION

Reasons: *Local:

-Trauma from occlusion . –periapical infection, cyst

and tumor . -Embedded teeth .

*Systemic:Deficiency of Ca or vitamin A and D ; hypothyroidism

Types of cemental Repair

1 -anatomic repair:Occurs when the degree

of destruction is low.2 -functional repair:

Occurs when the degree of destruction is high.

CLINICAL CONSIDRATION

1 -Ankylosis:Fusions of cementum to alveolar bone.

2 -Extraction of teeth.

3 -fracture.

Thanks for your attention

Prepared by: -Amani abdoNaser ..B)(

-Bahia abdrahman .. B(15) -Daneen ..B(2)

-Iman ..B)( -Suad Mohammed .. B(17)

-Tariq ..B)(