PRESENTED BY:

Dr Harshavardhan Patwal

INTRODUCTION PHYSICAL PROPERTIES OF CEMENTUM CHEMICAL COMPOSITION CELLS OF CEMENTUM CLASSIFICATIONS LOCATION AND FUNCTION OF TYPES OF

CEMENTUM INCREMENTAL LINES CEJ CDJ REPAIR ALTERATIONS IN CEMENTUM PERIODONTAL REGENERATION REFERENCES

Cementum is a specialized hard layer of calcified mesenchymal tissues which forms the outer covering of the anatomical root.

First demonstrated microscopically in 1835 by 2 pupils of Purkinjee.

It is also called as Substantia Ossea

Human Cementum is avascular & has no innervation.

It consists of a calcified interfibrillar matrix and collagen fibrils

1. Hardness :

Hardness less than dentin.

Least calcified.

2.Colour :

Light yellow in colour.

Dull surface (Lack of Lusture)

Darker hue than enamel.

3.Permeability :

More permeable than dentin.

In some areas canaliculi of cementum may becontiguous with with dentinal tubuli(Blayney et al ,1941)

It should not be considered as an engineering material that CEMENTUM has an absolute value for hardness and elastic modulus. ( Clark, 1997 ).

Cellular cementum is less calcified and has a lower hardness and elastic modulus than acellular cementum, which is more highly calcified ( Rautiola and Craig, 1961 ).

Apical cementum exhibits the least elastic modulus and hardness values ( Clark, 1997 ).

The hardness and elastic modulus also vary within teeth, depending on the direction of structural arrangement ( Berkovitz et al. , 1992) and different mineral content in the structure of cementum ( Henry and Weimann, 1951)

4.Thickness :

Coronal ½ of root : 16-60 micron.

Apical third of root : 150-200 micron.

& furcation area

Thinnest at CEJ.

Surrounds the apical foramen andsometimes lines the root canal

5. SURFACE TEXTURE

Mosaic (mogul like) pattern(Vrahopoulos et al)

On dry weight basis Cementum contains 45%-50% of inorganic substances & 50%-55% organic material and water.

ORGANIC MATRIX

◦ Collagen Type I (90%) (Birkedal-Hansen et al,1977)

◦ Collagen Type III (5%)-Found in high concentration during development and repair or regeneration

Sharpey’s Fibers◦ Collagen Type I(Mainly)

◦ Collagen Type III coats Type I Collagen of Sharpey’s fibers.(Rao et al.1975)

• Collagen Type XII is a fibril associated

collagen with interruped triple helices that binds to type I collagen and also to non-collagenous matrix proteins

Trace amounts of other collagens, including type V, VI, and type XIV are also found.

Proteoglycans(Closely associated with cementoblasts and distributed throughout the matrix)◦ Chondroitin Sulphate (majority),Dermatan Sulphate

,Hyaluronate,Keratan sulphate-fibromodulin,lumican, versican ,biglycan ,Tenascin and osteoadherin are present.

Initial mineralization and fiber attachment

At CDJ they help in attachment of cementumto dentin and heps in resisting occlusal load

Non Collagenous Proteins(Found in cementoblast layer and precementum layer)◦ Alkaline phosphatase,Bone sialoprotein

,osteopontin, Osteonectin and osteocalcin

◦ Dentin matrix protein-1 and Dentin Sialoprotein

◦ Enamel like proteins (Slavkin et al,1989)

◦ Fibronectin &Tenascin

◦ Cementum attachment protein(CAP)(Snarayanan,1996)

◦ GLUT-1,CP-23,CEM-1

Alkaline Phophatase◦ Formation and mineralization of cementum◦ Supersaturation of phosphate ions, released from

organic phosphate esters, would result in the precipitation of calcium phosphate salts

◦ Although alkaline phosphatase exists in a plasma membrane bound form, part of the enzyme may also be bound to the extracellular matrix

OSTEOCALCIN(Bone gla protein)◦ marker for maturation of cementoblasts that may

regulate the extent of mineralization. FIBRONECTIN AND TENASCIN◦ Bind cells to extracellular matrix

BONE SIALOPROTEIN ( Bronckers et al,1994)◦ cell adhesion properties◦ Demonstrated on AEFC at the time of mineralisation

(MacNeil et al,1994)◦ Promotes mineralization during cementogenesis

OSTEOPONTIN ( Bronckers et al,1994)◦ Adhesion protein,present at cement lines◦ Mediates cell attachment and cohesion of matrix

molecules at incremental lines.◦ Regulates mineralization during cementogenesis

Both have arginine-glycine-aspartic acid sequences that mediate cell attachment to mineralized tissue

OSTEOCALCIN◦ Marker for maturation of cementoblasts

◦ Regulates mineralization

ENAMEL LIKE PROTEINS- HERS cells may synthesize enamel proteins Their presence is limited to a very short,

cervical region on which cementum is deposited

Sporadic expression along the root in porcine teeth(Bosshadt,2000) and in rodent molars in association with epithelial cells entrapped in CIFC (Bosshadt,1994)

Cementum Attachment Protein◦ Collagenous cementum derived protein◦ CAP is found in the developing ( Saito et al., 2001) and

mature cementum matrix and cementoblasts◦ Immunolabeling in vitro is localized to the cell membrane

and fibril-like structures, and, in vivo, is found in cells associated with calcified bodies

◦ CAP is a marker molecule for cementogenesis (Arzate et al., 1992a), and that CAP is related to the development of the cementoblast phenotype (Pitaru et al.,1993).

◦ Binds to hydroxyapatite components of cementum◦ Chemotaxis of osteoblasts and fibroblasts ◦ Increases attachment of osteoblasts and fibroblasts to

cementum.(Narayanan,1998)

Growth Factors (Cho and Garant 1988)◦ TGFbeta,FGF1 and 2,BMPs,EGF ,PDGF are seen

BMP-2, -4, and -7, promote differentiation of cementoblastprecursor cells.

BMP7(Osteogenic protein 1)-induces new cementum on surgically denuded root surface in baboon(Ripamonti,1996)

◦ Cementum derived growth factor(CDGF)(Ikezawa et al,1997) Insulin like growth factor(IGF-1)like molecule

Mitogen for gingival fibroblasts ,periodontal cells and vascular smooth muscle cells

reveals a synergistic potentiation in the presence of EGF

◦ OPG,RANK-RANKL are also found Role in controlling osteoclastic mediated bone and root

resorption

TRANSCRIPTION FACTORS◦ Runx-2(Runt related transcription factor2)

seen in dental follicle cells,PDL cells,cementoblastsand cementocytes

involved in cementoblast differentiation.

Cementum is less mineralized than dentin

Hydroxyapatite(45-50%) with small amounts of amorphous calcium and phosphorus present◦ Mineral crystals are oriented parallel to the long axis of

the collagen fibers◦ Crystal size is smaller as compared to enamel

Highest fluoride content of all mineralized tissues

0.5-0.9%Mg

Traces of Cu ,Zn and Na.

CELLS OF CEMENTUM Cementoblasts

Cementocytes

CEMENTOBLASTS

cementoblasts are engaged in the formation of both CIFC and AIFC . Large, cuboidal cells with a round, euchromatin-rich nucleus and the full cytoplasmicarmamentarium required for protein synthesis and export(Furseth, 1969;).

The AEFC is formed by a class of cementoblasts that morphologically resemble periodontal ligament fibroblasts (Bosshardt and Schroeder,1991).

Cementoblasts are involved in the production of collagen fibers

Non collagenous proteins,proteoglycans and various growth /differentiation factors play important role in differentiation of cementoblasts from precementoblasts

Cementoblasts of AEFC type produce sharpey’s fibers and that of CIFC type produce intrinsic collagen fibers

◦ Rapid formation and a multipolar mode of matrix deposition are held responsible for the entrapment of ,cementoblasts in the cementum matrix (Bosshardt and Schroeder, 1992)

◦ These entrapped cells with reduced secretory activity are called as cementocytes residing in lacunae

◦ Cementocytes have processes that lodge in canaliculi that communicate and extend all the way to the surface

◦ Nourishment is by diffusion from Preiodontal ligament into canaliculi of cementocytes

◦ Cementocytes in deeper layers are not vital as cementumlacks a vascular system that can keep cementocytes alive in deeper portions of the matrix.

◦ Loss of intracellular organelles and ultimate cell death is progressive in the deeper layers of cellular cementum

CIFC FORMING CEMENTOBLAST

CEMENTOCYTE

AEFC FORMING CEMENTOBLAST

RADICULAR CEMENTUM◦ Derivative of dental follicle, proper covers the entire

dentin of the root from CEJ to the apex◦ It extends partially into apical foramen to line the apical

walls of the root canal

CORONAL CEMENTUM◦ In herbivores like guinea pig, cattle,horse etc cementum

is found on anatomic crown where it covers the enamel.◦ In humans it is restricted to areas of reduced enamel

epithelium

I. Based on time of formation (Gottlieb,1942)

Primary cementum

Secondary cementum

PRIMARY CEMENTUM-◦ Devoid of cells

◦ Contains randomly oriented collagen fibrils embedded in a granular matrix

SECONDARY CEMENTUM-◦ Contains cells

◦ Coarse collagen fibers oriented parallel to root surface and sharpey’s fibers perpendicular root surface

II.Based on Fibers (Selvig,1965)

Extrinsic fibers

Intrinsic fibers

Two sources of collagen fibers in cementum are:

Sharpey’s fibers(extrinsic)- (Romanos et al,1991)

◦ Terminal portions of the principal fibers that insert into cementum & bone are termed as “Sharpey’sFibers”.

◦ Oriented perpendicular to root surface◦ Produced by cells of the dental follicle during

development and later by periodontal ligament fibroblasts

◦ These have a principal role of supporting the tooth within jaw.

◦ 5-7microns in diameter.◦ Mineralized partially with unmineralized core

Fibers of cementum matrix(intrinsic)-(Selvig,1965)

◦ Produced by cementoblasts or cementocytes◦ Oriented parallel to root surface◦ 1-2 microns in diameter◦ Uniformly mineralized◦ Mainly for repair

III. Based on Presence or Absence of Cells

Cellular cementum

Acellular cementum

First formed cementum

Covers cervial third or half of the root

Contains sharpey’s fibers and intrinsic fibers but no cells

Formed before tooth reaches occlusal plane

Thickness-30-230microns (Simpson,1965)

Intrinsic fibers are calcified and irregularly arranged or parallel to the surface (Schroeder,1986)

Most sharpey’s fibers are perpendicular to root surface but others enter from several different directions

Sharpey’s fibers are calcified with mineral crystals oriented parallel to fibrils

In 10-50 micron wide zone near CDJ they are partially calcified

Peripheral portions of sharpey’s fibers are more calcified than interior regions(Jones et al,1972)

Their size ,number and distribution increase with function(Inoue et al,1962)

Formed after tooth reaches occlusal plane

More irregular

Contains cementocytes in lacunae communicating with each other through anastomosing canaliculi

Less calcified than acellular type (Ishikawa et al,1964)

Sharpe’s fibers occupy smaller portion.Intrinsic fibers are more in proportion.

Completely or partially calcified or may have a central uncalcified core surrounded by a calcified border.(Selvig,1965)

Absent in single rooted teeth

IV) On the basis of location, structure, function,rate of formation, biochemical composition and degree of mineralization cementum can be classified as(Schroeder,1992):

1. Acellular Afibrillar Cementum

2. Acellular Extrinsic Fiber Cementum.

3. Cellular Mixed Stratified Cementum.

4. Cellular Intrinsic Fiber Cementum.

5. Intermediate cementum

Contains homogeneous matrix rich in GAGs.(Schroeder,1986)

Enamel organ may produce mesenchymalproteins found in cementum and form AAC

Produced by cementoblasts Found as coronal cementum at

dentinoenamel junction(most common in molars)

Thickness of 1-15microns

Enamel epithelium degenerates at its cervical termination

Allows connective tissue to come in direct contact with

enamel

Follicular Connective tissue cells(cementoblasts)come in

contact with enamel & produce afibrillar cementum

Afibrillar cementum remains in contact with connective tissue cells for long time

Fibrillar cementum is deposited on afibrillar cementum thus increasing thickness of cementum

FORMATION OF AAC

Extrinsic fibers but no cementocytes

Product of fibroblasts and cementoblasts

Sharpey’s fibers are continuous with the fibers of PDL

Extrinsic fibers are mineralized except for their inner cores in a zone 10-50micron wide near CDJ

Degree of mineralization is 45-60%

Cementoid layer is absent

The innermost layer is less mineralized

The outer layers are characterized by alternating bands of more and less mineral content that run parallel to the root surface.

AEFC fibers increase in thickness with age and the rate and extent of thickening vary in different teeth(Sequeira et al 1992)

First cells that align along the newly formed, but not yet mineralized,mantle dentin surface exhibit fibroblastic characteristics.

Cells deposit collagen within the unmineralizeddentin matrix so that fibrils from both matrices interdigitate.

Mineralization of the mantle dentin starts internally and then spreads across cementumthus establishing the dentin–cementum junction.

Thin mineralized layer with a short fringe of collagen fibers implanted perpendicular to the root surface is formed

The cells on the root surface continue to deposit collagen so that the fiber fringe lengthens and thickens and secrete non collagenous proteins.

After 15–20 um of cementum has been formed, intrinsic fibrous fringe connects to developing PDL fiber bundles

Cementoblasts then produce non collagenousproteins ;collagen fibrils that embed in it will be formed by pdl fibroblasts.

Cementocytes enclosed in lacunae embedded in collagenous intrinsic fibers

Formed by cementoblasts

Less mineralized than AEFC. Its because of ◦ Heterogeneous collagen organization

◦ its rapid speed of formation

◦ the presence of cells and lacunae

Layer of unmineralixed matrix-cementoid is present.

Similar to bone

After at least half of the root has been formed, cementoblasts start forming cementum whose constituent collagen fibrils are produced by the cementoblasts .

Collagen is deposited on the unmineralizeddentin surface such that fibrils from both layers intermingle.

Intrinsic fibers follow spiral course along and around the root.

Noncollagenous matrix proteins fill in the spaces between the collagen fibrils

A layer of unmineralized matrix, cementoid, is established at the surface of the mineralized cementum matrix, with the mineralization front at the interface between the two layers.

As the process proceeds, some cementoblasts become trapped in the matrix they form. These entrapped cells, with reduced secretory activity, are called cementocytes and sit in lacunae.

Extrinsic and intrinsic fibers and contains Cementocytes

Intrinsic fibers predominate over extrinsic fibers. Co-product of fibroblasts and cementoblasts Alternating layers of AEFC and CIFC Covered by thin layer of AEFC for attachment to the

PDL Increases in thickness throughout life. Cellular mixed stratified cementum generally has a

lower mineral content than acellular extrinsic fiber cementum.

After the formation of CIFC when the periodontal ligament becomes organized, cementum may form around some of the periodontal ligament fiber bundles.

These get incorporated into cementum(CIFC) and become partially mineralized.

In human teeth, incorporation of periodontal ligament fibers into CEFC occurs only rarely, essentially in the AEFC component of CMSC.

Poorly defined zone near CDJ separating cementum(AEFC) from dentin

Rich in glycoproteins but has sparsely produced collagen fibers.(Yamamoto,1969)laminin and collagen type IV are also present

HERS cells may synthesize amelogenins that accumulate on the forming root surface to form this layer(Slavkin,1989)

HERS cells become trapped in a rapidly deposited dentin or cementum matrix giving rise to intermediate layer

Dentinal in origin with no tubules but wide spaces which are enlarged terminals of dentinal tubules.

may be continuous or present in isolated areas

No characteristic features of either dentin or cementum

Also called as HYALINE LAYER OF HOPEWELL SMITH as it appears hyaline or structureless

1. Acellular Afibrillar Cementum-◦ Cervical enamel surface

◦ Occurs as Spurs extending from AEFC or isolated patches on enamel surface close to CEJ

◦ Uncommon in humans,normally seen in herbivores

◦ Produced as an aberration of development process

◦ Little functional importance as not involved in fiber insertion or anchorage

2. Acellular Extrinsic Fiber Cementum.

◦ From cervical margin of the tooth & covers 2/3 of the root ◦ In single rooted teeth ,extends till apical foramen◦ Thickness-30-230microns containing several

incremental lines◦ Rate of appositional growth is 0.1microns/day that is

very slow as compared to cellular cementum

◦ FUNCTION- Tooth anchorage through sharpey’s fibers

3. Cellular Mixed Stratified Cementum

◦ Apical third and interradicular regions of premolars and molars.

◦ Thickness-100-1000microns

◦ FUNCTION-Root anchorage and adaptation

4. Cellular Intrinsic Fiber Cementum◦ Found in resorption lacunae,fracture sites and

may cover apical third and interradicular regions of premolars and molars.

◦ Rate of formation of CIFC is 0.5-3.0microns/day◦ FUNCTION-Repair and Adaptation

As it can be formed very rapidly and focally it helps to Reshape root surfaces to accommodate for physiologic shift and non physiologic shifting of teeth in the tooth socket

for the repair of resorption sites(Schroeder,1986)

5. Intermediate cementum –

◦ CDJ separating cementum and dentin

◦ Seen in apical 2/3 of molars and premolars

◦ hyaline layer is involved in “cementing” cementumto radicular dentin.

Acellular and cellular cementum are arranged in lamellae separated by incremental lines parallel to the long axis of the root

Represent rest periods in cementumformation

More mineralized than adjacent cementum(Romanos et al,1992)

Incremental lines are farther apart in cellular cementum than in AEFC

Zander and Hurzeler(1958) stated that cementumis a better age estimating tissue than others

Incremental lines in cementum can be used as most reliable age marker than any other morphological or histological traits in skeleton

Evaluation of annual incremental lines of dental cementum is one of potentially valuable methods for biological age estimation in forensic anthropology and digitalized visual analysis system enhances the count and provides better results. (Bojarun et al,2003)

The root resorption is not continuous, and has resting periods. In the resting period, cementumdeposits in resorbed root surface.

The present study examined apices of roots of human deciduous incisors with apical periodontitis and roots of sound deciduous incisors by light and transmission electron microscopy

Root dentin and original cementum had a severe irregular caved surface. Cementum was partially deposited on the caved root surfaces. The deposited cementum had made the caved root surface relatively flat. The cementum was lax and had some defects. The deposited cementum was belt-like in shape and had a stratified structure. (NORIYUKI et al,2004)

Each layer had various structures consisting of abundant microfibrils and fine granular materials, microfibrils, granular materials, and collagen fibrils, a few fibrils and granular materials and a relatively homogeneous structure.

The original cementum had many collagen fibrils, such as intrinsic and extrinsic fibers, and no granular materials or homogeneous structure.

Therefore, structure of the deposited cementumwas very different from that of original cementum in deciduous teeth and from that of deposited cementum in permanent teeth.(Yawaka et al,2003)

The interface between the Cementum &

Enamel at the cervical region of tooth isknown as cementoenamel junction.

It is of 3 types (Cloquet,1899 and

Thoreson,1917)

1. Cervical end of Enamel is overlapped by cementum

for short distance.(60%)

2.Edge to edge relationship between cementum and enamel(30%)

3.Enamel and cementum fail to meet(10%)

Enamel epithelium in the cervical portion of the root is delayed in its separation from dentin

Zone of root is devoid of cementum and for some time covered by reduced enamel epithelium.

Gingival recession may result in accentuated sensitivity because of exposed dentin

This may result in osteoclast mediated root resorption and root caries.cervical erosion and abrasion

4. Enamel overlapping cementum

In deciduous teeth :

Enamel and cementum meeting edge to edge is commonest followed by cementumoverlapping the enamel

Others are observed rarely

It is interface between the dentin & cementum.

Scalloped in deciduous teeth & smooth in the

permanent teeth.

Large quantaties of collagen associated with

GAGs like Chondroitin Sulphate and Dermatan

Sulphate increase in water content

Stiffness redistribution of occlusal loads to

the alveolar bone.

It is 2-3microns wide

Cemental fibers intermingle with the dentinal fibers at the CD junction more in cellular cementum than in acellular cementum

Fibers and Proteoglycans help in attachment of cementum to dentin

Mineralization of the mantle dentin starts internally and does not reach the surface until collagen fibrils of dentin and cementum have blend together.

Mineralization spreads through the dentin, across the CDJ and into cementum

Amalgamated mass-strong union between cementum and dentin

1. ANCHORAGE◦ Cementum serves as a medium for the

attachment of collagen fibers that bind the tooth to alveolar bone

2. 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.

3. REPAIR◦ Major reparative tissue for root surfaces in case of

fractures and resorptions.◦ Cellular cementum is formed ◦ Repair of root fractures ◦ Sealing 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

Cementum repair requires viable connective tissue

Repair can occur in devitalised or vital tooth

2 kinds of repair:◦ Anatomic repair-Outline of the root is restored

◦ Functional repair-Shape of the root is not restored.

BY ACELLULAR CEMENTUM

BY CELLULAR CEMENTUM

FIRST BY CELLULAR CEMENTUM & THEN BY BYACELLULAR CEMENTUM

ANKYLOSIS(Abnormal Repair)

Fusion of cementum with alveolar bone with obliteration of the periodontal ligament.

ETIOLOGY- result of repair (deposition of bone) after cemental resorption.

Develops after chronic periapical inflammation ,tooth replantation ,occlusal trauma and around embedded teeth

Common in primary teeth (Mcnamara et al 2000)

Repair cementum adheres very well to the root surface if a resorptive phase precedes new matrix deposition implying that odontoclasts precondition the root surface.

Chemical preconditioning of the root surface with acids or chelators is an often-applied step in periodontal therapy (Lowenguth,1993).

1. PHYSIOLOGIC◦ Age changes

2. ORTHODONTIC TOOTH MOVEMENT

3. TRAUMA FROM OCCLUSION

4. CEMENTAL APLASIA

5. HYPERCEMENTOSIS

6. PATHOLOGIC◦ Effect of gingival inflammation

Subsurface alterations

Cervical root resorption

◦ Exposure to oral environment Bacterial contamination

Hypermineralisation

◦ Aggressive Periodontitis

7. SYSTEMIC DISEASES

CONTINUOS DEPOSITION-Increase in cemental width from 5-10 times (Berglundh et al)

Continuous deposition of cementum after tooth eruption more apically and lingually (Vander welden,1984)

Accumulation of resorption bays explains increase surface irregularities (Grant Det al,1972)

Permeability decreases with age Between 11 and 70 years of age , the average thickness of

cementum increases three fold with the greatest increasein the apical region.

Average thickness of 95um at age 20 ,215um at age 60have been reported.(Zander et al,1958)

PHYSIOLOGICAL ACTIVITY OF CEMENTOCYTES

◦ Cementocytes close to surface resemble cementoblasts

◦ In deeper layers advanced nuclear and cytoplasmicchanges occur or the lacunae may appear empty

Cementum is thicker in areas exposed to tensional forces on labial and lingual surface of incisors(Geppert,1974)

Thicker in distal surfaces than in mesialsurfaces because of functional stimulation from mesial drift over time.(Polson et al,1990)

The deposition of considerably more new cementum has been noted on the tension side compared with the pressure side of the root surface of teeth undergoing orthodontic tooth movement (Dastmalchi R et 1990)

Root resorption◦ Number of teeth resobed and severity of resorption

makedly increased by orthodontic treatment(Massler,1954)

Spike like excrescences(cemental spikes)-This occurs due to excessive orthodontic force(Lester,1969)

Hypercementosis-◦ Localized Hypercementosis is evident in case of

trauma from occlusion

Root resorption-◦ in severe trauma ,resorption may continue into

dentin

◦ Repair is done by deposition of CMFC.

ABNORMALITIES OF THICKNESS (Leider et al,1987)

CEMENTUM APLASIA or HYPOPLASIA

CEMENTUM HYPERPLASIA or HYPERCEMENTOSIS

1. CEMENTUM APLASIA or HYPOPLASIA-◦ Absence or paucity of cellular cementum

2. CEMENTUM HYPERPLASIA or HYPERCEMENTOSIS◦ Excessive deposition of cementum

◦ Age related phenomenon

◦ May be localized or entire dentition

Seen in neoplastic or non neoplasticconditions like benign cementoblastoma,cementifying fibroma,periapical cemental dysplasia,floridcemento-osseous dysplasia and benign fibro osseous lesions. (Leider et al,1987)

In localized hypercementosis a spur or prong like extension may be formed

ETIOLOGY for localized Hypercementosis-teeth WITHOUT antagonist,low grade periapical irritation,adjacent to inflammedperiapical tissue, excessive occlusalload,enamel pearls and epithelial rests(excementoses)

Generalized thickening of the cementum with nodular enlargement of the apical third of the root. (Lester,1969)

ETIOLOGY for generalized thickening-Paget’s disease,acromegaly.arthritis,calcinosis,rheumaticfever and thyroid goiter (Leider et al,1987)

Embedded teeth or non functional teeth show hypercementosis with reduction in sharpey’s fibers.

Spike like excrescences(cemental spikes)-coalescence of cementicles that adhere to root or calcification of periodontal fibers at the sites of insertion into cementum (Lester,1969)

CAUSE-Excessive tension from orthodontic appliances or occlusal forces

EXCEMENTOSIS IN BIFURCATION OF MOLARS

RADIOGRAPHICALLY-periapical cementaldysplasia, condensing ostietis and focal periapical osteopetrosis may be differetiatedfrom hypercementosis by a shadow located outside the periodontal ligament and lamina dura. (Wood et al,1984)

No treatment required.

CONSIDERATION-multirooted tooth may require sectioning before extraction.(Basdra et al,1997)

Loss of Cemental Vitality.This causes

◦ Apical migration of epithelial attachment

◦ Deep Pocket formation

◦ Diffuse alveolar atrophy

PHYSICAL CHANGES IN CEMENTUM

◦ Microhardness of the cemental surface is reduced because of demineralization(Emslie and Stack,1958)

◦ Microradiography shows zone of cementum with a radio dense line 10-50 um wide at the tissue’s surface

Decrease in Hardness and modulus of elasticity signifies demineralisation thus increased susceptibility to root resorption (Reitan, 1969)

An earlier interindividual investigation of hardness and elastic modulus between a control (0 cN), heavy force (225 cN), and light force (25 cN) group found that there were no significant differences in the hardness and elastic modulus of cementum between the groups ( Darendelileret al. , 2004 ).

Loss of or reduction in cross banding of collagen near cementum surface

Subsurface condensation of organic material of exogenous origin

CHEMICAL CHANGES IN CEMENTUM

Absorption or depletion of major mineral components leading to◦ Areas of hypermineralization-minerals increased

are calcium ,Magnesium,Phosphorus and fluoride◦ Areas of demineralization

Root caries

Root resorption

Cementum resorption may be caused by :

1. Local Factors◦ Trauma from occlusion , orthodontic movement,

pressure from malaligned erupting teeth, cysts and tumours , teeth without functional antagonist, embedded teeth , replanted and transplanted teeth.

2. Systemic Factors◦ Calcium deficiency , hypothyroidism , Hereditary

fibrous osteodystrophy and Paget’s disease

3. Idiopathic

RESORPTION PRESENTS-

Bay like concavities in root surface

Multinucleated giant cells and large mononuclear macrophages are found

Several sites may coalesce to form large areas of destruction

Resorption may alternate with deposition of new cementum

REVERSAL LINE-Newly formed cementum is demarcated from root by a deeply staining irregular line

◦ Few collagen fibers and high amounts of proteoglycans with GAGs

Bacterial enzymes and acid metabolites might be present to induce localized damage to the cementum and to partially mineralized cuticle which eventually covers the exposed root surface (Eide et al,1984)

CALCULOCEMENTUM-Calculus embedded deep into the cementum may appear morphologically similar to cementum

Adriaens et al 1988 described bacterial invasion into root cementum:◦ Multiple lacunar defects filled with bacterial plaque were

confluent forming multilocular defects

Surface of bottom of lacunae is rough with numerous single bacteria present between globular and granular components of the exposed intertubular dentin

In many tubular orifices bacteria invading tubular dentin were seen

In zone where attachment loss has occurred multiple dentinal tubules in the outer third of radicular dentin contained cocci,rods and filamentous bacteria

Difficulty in eliminating bacteria by mechanical means as it involves removal of substantial amounts of radicular dentin

Possibility of retrograde infection to the pulp causing pulpitis

The presence of a highly mineralized surface layer in the cementum following exposure to the external environment has frequently been detected by microradiography , chemical analysis ,electron microprobe analysis and nuclear resonance reaction analysis.

The development of a hypermineralized zone apparently depends on the ionic concentration of inorganic elements in the local environment.

Furseth found that healthy cementumexperimentally exposed to the oral environment by a gingivectomy procedure acquired a hypermineralized surface zone within 2 1 days.

This process could be greatly enhanced by treating the root surface with a 2% solution of sodium fluoride for 10 minutes.

Similarly, if the original surface layer of cementum is removed by root planing, a hypermineralized zone may be re-established within 4 to 8 weeks(Selvig,1969)

Ultrastructurally, the hypermineralizedsurface zone is characterized by ◦ presence of large, atypical crystals, irregular crystal

orientation indicative of demineralization and remineralization processes

◦ loss of characteristic collagen cross banding(Selvig,1969)

◦ increased fluoride content(Selvig,1977)

In localizesd aggressive periodontitis the permanent incisors and first molars show advanced pocket formation ,loss of attachment and advanced alveolar bone resorption

Tissue destruction develops rapidly without associated inflammatory response

Root surfaces of affected teeth have hypoplasticcementum (Lindskog,Blomlof,1983)

Sometimes serum alkaline phosphatase is low

HYPOPHOSPHATASIA-(Whyte,1994)

◦ Heriditary disease ,autosomal recessive trait

◦ Cementum formation on primary anterior teeth is defective

◦ Premature loss of teeth without root resorption is first sign of the disease

◦ Other skeletal abnormalities are present

◦ Alkaline phosphatase levels are low.

DOWN SYNDROME(Bimstein,2008)◦ Narrow cementum areas

PAPILLON-LEFE`VRE SYNDROME◦ Aso et al reported an abnormal keratin molecule in

Papillon-Lefe`vre syndrome as well as other structural defects as in the cementum and a functional imbalance of collagenolytic activity in the periodontal ligament.

A striking radiographic appearance with a bulbous enlargement of the roots together with pulp stones is seen in teeth. 'Giant channels' and vascular inclusions resembling 'intermediate cementum' are prominent within this area.(Pope,1992)

Cementum apical to the dentogingival junction exhibited resorption lacunae and areas of poor structural definition characterized by aplasia and hypoplasia (hypomineralization).

Areas of hypoplasia presented as distinct irregular surfaces with a pebbly or globular-like appearance. Alteration in cementum formation and maturation may play a role in the etiology of early-onset periodontitis.(Waldrope,1995)

Acellular cementum in all teeth, almost complete missing of cellular cementum, normal intermediate cementum

Ideally, the regenerated cementum should closely resemble the AEFC, because◦ it contributes most to the attachment function

(Schroeder, 1992; Bosshardt and Selvig, 1997). ◦ More mineralized thus takes more occlusal load

In most periodontal regeneration studies, the quality of the attachment function is questionable, because ◦ the newly formed cementum is cellular, ◦ numerical density of inserting fibers is low, ◦ and the interfacial tissue bonding appears to be weak.

Titanium Implants are ankylosed to bone without any intervening connective tissue.

Buser et al,1990 studied that when implants were placed in contact with retained root tips whose PDL served as a source for cells which could participate in the healing process

Microscopic analysis revealed that a distinct layer of cementum on the implant surface was formed and a periodontal ligament with collagen fibers perpendicularly oriented to the implant surface, implanted into the cementum on the implant surface as well as to the opposing bone.

BONE CEMENTUM

• Bone is present at various anatomical locations and is structurally adapted to meet its specific supportive requirements.

• Bone formation may occur directly through intramembranousossification, indirectly through chondral ossification, or in growth cartilage through endochondralossification.

• Lamellar bone is characterized by matrix layers of parallel collagen fibrils and is regarded as a complex rotated plywood like structure (Weiner et al., 1999).

• Cementum is a heterogeneous mineralized tissue that covers the entire root surface of the tooth, and may also be found over the cervical enamel and line the apical wall of the root canal system.

• Several Types of cementum that differ from one another with respect to location, structure, function, rate of formation, proportional biochemicalcomposition, and degree of mineralization ( Schroeder, 1992)

• CIFC consists of an alternate lamellar pattern resembling the twisted plywood structure of lamellar bone

BONE CEMENTUM

•'cement line', which marks the interfacebetween new and old bone

•Bone has unmineralized osteoid layer

•Osteoblasts are large, cuboidal cells that usually form a single layer that covers all periosteal or endostealsurfaces where bone formation is active (Marks andPopoff, 1988).Their nucleus is round,and their cytoplasm is filled with a prominent Golgi complex and abundant RER

•The lack of collagen fibrils and the common presence of typical bone- and cementum-related noncollagenousproteins draw attention to a certain parallel between the AAC and the cement line in bone.

•CIFC and AIFC have unmineralizedcementoid layer

•Cementoblasts engaged in theformation of both CIFC and AIFCare large, cuboidal cells with around, euchromatin-rich nucleusand the full cytoplasmic armentariumAEFC producing cementoblasts are pdlfibroblasts

BONE CEMENTUM

• Bone has osteocytes in lacunae entrapped in the matrix

• Neighboring osteocytes are interconnected by tiny cytoplasmic processes extending through a dense canalicular system, allowing for diffusion of metabolites and cell communication.

• CIFC has cementocyteslocated in lacunae entrapped within matrix

•Canalicular system isAlso be present in the CIFC matrix.

Amelogenin Ameloblastin Cementum derived growth factor Cementum attachment protein-Cementoblasts GLUT-1(Koike et al,2005)-cementoblasts and

cementocytes CP-23(Cementoblast derived protein)(Narayanan et

al)-Cementoblasts The Dlx-2 and Dlx-3 (distal-less gene) homeoprotein

transcription factor-innermost cementoblasts and entrapped cementocytes

cementoblasts and cementocytes

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