CEMENTUM

SUBMITTED BY:

ANURADHA BDS 3RD

PROF.

Submitted to:-DEPARTMENT OF CLINICAL PERIODONTOLOGY & ORAL IMPLANTOLOGY

HOD & PROF.- DR. RANJAN MALHOTRA

CONTENTS INTRODUCTION DEVELOPMENT TYPES OF CEMENTUM STRUCURE AND COMPOSITION ACELLULAR AND CELLULAR CEMENTUM CEMENTOENAMEL JUNCTION DENTINOCEMENTAL JUCNTION PATHOLOGY ANKYLOSIS CEMENTUM RESORPTION

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.

Structure of tooth and its

parts

Histological view of cementum

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.

TYPES OF CEMENTUM:1.ACELLULAR or PRIMARY CEMENTUM

2.CELLULAR or SECONDARY CEMENTUM

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.

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.

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.

CELLULAR CEMENTUM

Cellular cementu

m

Acellular cementum

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 5-10% of cases cementum and enamel fail to meet.

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.

Dentino- cemental junction

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..

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.

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.

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.

REFERENCES-Website- Wikipedia ,Google

Carranza’s bookDental anatomy and histology by dr.satish chandra

Thank you