cementum in disease[nalini]
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Non-Collagenous Protein: Cementum is rich in
glycoconjugates, which represent either glycolipids,
glycoproteins or proteoglycans and harbours a variety
of other proteins.
The predominant noncollagenous proteins are :
1) Bone sialoprotein 3) Osteonectin
2) Osteoponitin 4) Fibronectin, Tenasin
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Time of formation
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Presence or absenceof cells within itsmatrix
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Origin of collagenous fibers of the matrix
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Depending on location & patterning
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Schroeder classification
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Smooth/Scalloped
Firm in attachment
Under Light microscopy
CDJ is visible in decalcified and stained histological section
Under Electron miscroscopy
CDJ is not distinct
Sometimes dentin is separated from cementum by a zone knownas intermediate cementum layer
This layer predominantly seen in apical two thirds of the
roots of molars and premolars., rarely observed in incisors ordeciduous teeth. This layer represents, areas where cells ofHERS becomes trapped in rapidly deposited cementum ordentinal matrix.
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60% to 65% Cementum overlapping theenamel
30% End-to-end relationship of enamel and
cementum
5% to 10% space between enamel andcementum with dentin
Recent study by Newvald L & Consolaro A in J. Endod.2000 Sep;26(9):503:8
have stated fourth type of CEJ was observed, wherein cementum overlappedby enamel
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Anchorage Attachment Adaptive and reparative function Walling in filled canals Repairing roots (horizontal fracture) Sealing of necrotic pulps by occluding apicalforamen Protecting underlying dentin
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CHANGES IN EXPOSED HUMAN CEMENTUM
The concept that alteration inchronically exposed cementum was first
suggested by Magitot. He noted thatnecrosis and resorption were the main
alteration in exposed cementum. Todate, exposed cementum has beenexamined for change in
a) Physical properties
b) Chemical compositionc) Permeabilityd) Structuree) Incorporation of bacterial products
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Changes in Physical properties :
Except for hardness
changes in the physical
properties of exposedcementum have not been
studied. Exposed non
carious cementum is softerthan unexposed cementum.
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Changes in Chemical
composi t ion
Inorganic portion of exposed noncarious cementum is increased by pickingup ion from the oral environment. The
fluoride concentration of exposedcementum (9180 ppm) is about twice thatof unexposed cementum ( 5570 ppm ).
A slight but statistically significant
depression in the citrate content ofexposed cementum has been reported.
The ground substance of cementum hasnot been chemically analysed.
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Changes in permeab i li ty :
Under some experimental
conditions cementum is
permeable to dyes. Exposedcementum exhibitsincreased permeability to
radioactive iodine.
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Changes in structu re :
Surface of exposed cementum
is hypermineralized upto a
depth of 10-35 um.
The presence of pathologic
granules is found in exposed
cemental surfaces.
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Incorporat ion o f bacter ial
products :
Toxic substances from oral cavity areincorporated into exposed cementum.
Amino acid found in the cell walls of
some bacteria was found in cariouscementum, but was not detected inexposed non carious cementum.
Recently, it has been shown that
endotoxin with high invitro toxicity canbe isolated from exposed cementum
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ALTERATION RESULTING FROM
PERIODONTAL PATHOLOGY
Effect of gingival inflammation :Subsurface alteration :
The long standing presence of an inflammatoryprocess in the gingival connective tissue results in anet loss of collagen & in breakdown of dentogingivalfibers. Although enzymatic breakdown of collagenfiber is obvious in the gingival soft tissue, theextension of this process into the hard tissue of theroot, with loss of collagen crossbanding &dissolution of mineral crystals has also beendescribed.
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Cervical root resorption :The development of large root
resorption defect in the cervical regionis, most likely, triggered by
inflammatory processes in the adjacentconnective tissue most frequentlycervical resorption is seen in cases ofhyperplastic gingivitis. Such resorption
generally has an underminingcharacter
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Analysis of root surface changes inperiodontitis :The first possibility that exists is thatthe cementum of certain individuals,through some inherent or acquiredphysical or chemical defect renders
that individual more susceptible toperiodontal disease
The second and more likely situation isthat the complex inflammatory,
enzymatic and molecular biologicinfluences which accompany periodontaldisease may produce physical orchemical changes which are detectable
in cementum.
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Cemental alteration with periodontalinflammation can occur even before the
junctional epithelium has migratedfurther apically onto the root surface.
These changes in root surfaces wall ofperiodontal pockets are significant
because they may perpetuateperiodontal infection, cause pain andcomplicate periodontal treatment.
The root cementum suffers surface,chemical, cytotoxic & structuralchanges
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Surface changes of cementum
SEM observationAreas of cementum which are exposed byperiodontal disease show varying changesdepending on their location.
At the base of pockets, the most recentlyexposed cementum may show a partial filling inone of the space between projections.
Cementum which has undergone a larger
exposure shows a complete covering of thenormal projections with what appears to be flatsheet like plaque and calculus formations.
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The cementum near CEJ demonstrates
extensive flat sheet like calculus formations.The root surface which is in association with
periodontal disease is also covered withcuticular material whose thickness varies from 1
to 4 um., and is of lamellar nature..
The roughness of the root surface probably isalso due to the uneven deposition of this cuticle.
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SurfaceMorphology ofthe tooth wall of periodontal pockets
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Chemical changes:
The nature of the difference between periodontally
normal and diseased teeth basically can becharacterized as either an absorption onto or adepletion from the cementum of major mineralcomponents such as magnesium, calcium and ofcertain trace elements such as silicon, copper, iron
etc. The cementum in association with the pocket wall
picks up iron which is a breakdown product of hememolecules and demineralized cementum once incontact with the oral environment binds calcium fromthe saliva.
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The uptake of minerals at the root surface is relatedto environment in which cementum is located.Exposure to oral cavity, saliva favouring
remineralization of the surface aspects ofcementum & organic constituents.
The mineral content of exposed cementum isincreased. The following minerals are increased in
diseased root surfaces.Calcium
Magnesium
PhosphateFluoride
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Cytotoxic Changes :
Bacterial penetration into the cementum can be foundas deep as the cemento dentinal junction.
Permeation of bacteria is facilitated by the occurrence
of minifracture and cracks, which sums to developfrequently in exposed cementum.
Bacterial invasion into cementum & root dentin is acommon sequence to chronic periodontal disease.
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More recently, bacterial Lypopolysaccharide have beendetected in the 40 to 70 um deep surface of periodontallydiseased roots.
Bacterial endotoxins have also been detected in the
cemental wall of periodontal pockets. Whether the toxinis actually absorbed or trapped in the tissue has notbeen established.
These imperfections can harbour endotoxin on asubmicroscopic basis and serve as a substrate for
inflammatory exudate.
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The component of this exudate can include substance
such as histamine, bradykinin, high molecular weightimmunoglobulins IgG, IgA, IgM and complement
The endotoxic which has been found in the cementumalso may act to produce direct labializations of the
lysozomal enzyme found within the cells of the tissuewhich then spill out into the tissues to effect theirresorptive activities.
The cementum may act to perpetuate the destructive
effects of periodontal disease by acting as a reservoir forpotentially destructive material.
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STRUCTURAL CHANGES :
Presence of Patho log ic Granu les:
These granu les extend 3-12 um into the su rface ofcementum from over ly ing plaque.
Hypotheses wh ich explain the format ion o f cementalgranu les inc lude 3 basic events .
1) Upon exposu re to the oral environment, unm ineral ized
areas of cemental col lagen are denatured, resu lt ing inloss o f structu ral character is t ics such as cros s-banding.
2) A reas where cemental co l lagen has been denatured,subsequent ly mineral ize by p ick ing up ions from the
oral environment.3) Upon decalci f icat ion , in the labo ratory areas where
cemental co l lagen has been denatured and o r depos itedare unmasked and become vis ib le.
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Granules appeared in 4 basic morphologic
patterns.:1. Grape like structure.
2. Long chain aggregate
3. Small isolated vacuoles4. A very long fissure like area.
Garrett, JS. Cementum in periodontal diseasePerio Abstr 23:6, 1975 [Review Article]
Areas of Deminerali ation
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Areas of Demineralization :
Areas of demineralization are commonly relatedto root caries, exposure to oral fluid andbacterial plaque resulting in proteolysis of theembedded remants of Sharpeys fiber.
The cementum may be softened and mayundergo fragmentation and cavitation.
Root surface caries progress around the teethand appear as well defined yellowish or light
brown areas covered by plaque and have a softor leathery consistency on probing.
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The dominant microorganism is aactinomycosis viscosus caries of the root
may lead to pulpitis, sensitivity of sweets
and thermal changes of severe pain.Pathologic exposure of the pulp occurs in
severe cases.
Root caries may be the cause oftoothache in patients with periodontal
disease and no evidence of coronal decay.
A f i d i li i
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Areas of increased mineralization:
The presence of a highly mineralized surface layer
in the cementum following exposure to the externalenvironment has frequently been detected by microradiography, chemical analysis, electronmicroprobe analysis and nuclear resonance
reaction analysis.This increased mineralization may be increased by
calcium and other ion derived from saliva andcrevicular fluid.
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Hypermineralized zone are 10 to 20 um
thick with areas as thick as 50 um. As loss or reduction in the cross banding
of collagen near the cementum surface
and a subsurface condensation of organic
material of exogenous origin have also
been reported.
That the mineral content of the cervical
portion indicated a higher mineral content
(Ca+ Mg and P) in the periodontally
involved teeth.
ULTRASTRUCTURAL CHANGES IN
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ULTRASTRUCTURAL CHANGES IN
PERIODONTAL ATTACHMENT:
From apical region following zonescan be distinguished.
Zone I A zone of intact connectivetissue fiber attachment tocementum in the apical and middleregions of the gingival attachmentof the root.
Zone II- A zone of partial destructionof the connective tissue fibers 0.5to 1.0 mm beneath epithelialattachment.
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ZoneIII-A zone of complete destruction ofconnective tissue in a narrow areabeneath the functional epithelium.
ZoneIV-Epithelial lining of cementum. Aspace of 0.1 to 0.2 um containing somegranular material but not recognizablefibrils can be seen between the epithelial
cells & the cementum at more cervicallevels.
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ALTERATION OF CEMENTUM :
Hypercementosis
Anky los is
Root fractu reRoot sensi t iv i ty
Roo t caries
AbrasionCemental tear
H t i
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Hypercementosis
Excessive deposit of cementum on root surface.
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Hyperp last ic Cementum
It may affect all teeth of the dentition, beconfined to a single tooth, or even affect onlyparts of one tooth. It may be diffuse orcircumscribed.
If the overgrowth improves the functionalqualities of the cementum it is termed acementum hypertrophy.
If the overgrowth occurs in non functional teethor if it is not correlated with increased function, itis termed hyperplasia.
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Factors associated with Hypercementosis
Local factors
b) Abnorm al occlu sal trauma
c) Adjacent inf lammation
d) Unopposed teeth ( implanted / embedded w ithout
antagonist)
Systemic factors:
a) Ac romegaly & pi tu i tary gigant ism
b) Arthr i t is
c) Calcino sis
d)Pagets disease of bone
e) Rheumatic fever
f) Thyro id go iter.
g) Vitam in-A defic iency.
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A k l i
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Fusion of cementum and alveolar bone wi thob l i terat ion o f periodontal ligament is termed
as ankylos is .
Pathogenesis :
Exact is unknown. Possib ly when the C.T of
the periodonta l memb rane is lost al low s
cementum , to come in di rect contact wi th
alveolar bone, resul t ing in fu sion of the two
oppos ing calc i f ied s tructu re general ly any
factor that can cause external roo t reso rpt ion
has the potent ial to resu l t in anky losis .
Anky los is
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Clinical features
Radiographic features Treatment
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Root fracture :
severe external forces such as blow or
biting on a hard object, fracture of the root
may occur
complete, horizontal or oblique fractures
followed by repair which includes
deposition of calcified tissue & embedding
of new periodontal ligament fibers.
S l f t i fl th lik lih d f
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Several factors influence the likelihood of
such repairs :
Exposure of site of fracture to oral cavity
with subsequent infection will interfere with
repair. The distance between fractured root ends
& inherent reparative capacity of the
individual also influence repair of completehorizontal or oblique root fracture.
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R t iti it
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Root sensitivity Root hypersensitivity is a common problem in
periodontal practice. It may occur spontaneously when root becomesexposed as a result of gingival recession or pocketformation, or it may appear after scaling & rootplanning & surgical procedure.
Root sensitivity occurs more frequently in cervicalarea of the root, where the cementum is extremelythin, scaling & root planning procedure may entirelyremove this thin cementum, inducing the
hypersensitivity.
Transmission of stimuli from the surface of the
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Transmission of stimuli from the surface of the
dentin to the nerve endings located in the dental
pulp or in the pulpal region of dentin may occur
through the odontoblastic process or owing to ahydrodynamic mechanism this causes the
sensitivity reaction. This can also evoke a pulpal
response leading to pulpititis and further pulp
damage.
R t i
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Root caries :At one time, it is referred to as Caries of cementum. It is
soft progressive lesion found anywhere on the root surfacewhich has lost C.T attachment and exposed to oralenvironment.
Exposure to oral fluid and bacterial plaque results inproteolysis of the embedded remnants of Sharpeys fiber.The cementum may be softened & undergo fragmentation &cavitation.Involvement of the cementum is followed by bacterialpenetration of the dentinal tubules, resulting in destruction ofthe dentin.
Since cementum is formed in concentric layers the micro-organism spread laterally between various layers.After decalcification of the cementum, destruction of theremaining matrix occurs with the ultimate softening &destruction of the tissue. It then proceeds to the dentin &finally pulpal involvement.
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The tooth may not be painful but
exploration of the root surface reveals the
presence of defect penetration of theinvolved area with a probe elicits pain.
Caries of cementum requires specialattention when the pocket is treated. The
nectrotic cementum must be removed by
scaling & root planning until firm toothsurface is reached, even if this entails
extension into dentin.
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Abrasion :
It is pathologic wearing away of tooth substancethrough abnormal mechanical process.
Abrasion usually occurs on the exposed root
surfaces of teeth. They cause remarkable wear of cementum &
dentin if the tooth brush carrying abrasivedentifrices is used injudiciously particularly inhorizontal rather than virtual direction. Vshaped or wedge shaped ditch is seen on theroot side of the CEJ with some gingivalrecession.
Cemental Tears :
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Detachment of fragment of cementum from the root surface is
known as a cemental tear
Cementum fragments displaced into the
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Cementum fragments displaced into theperiodontal ligament may undergo a varietyof changes.
New cementum may be deposited at the periphery &pdl fibers may become embedded in it, so as to establisha functional relationship between the tooth on one
aspects and alveolar bone on the other.The detached cementum fragments may be completelyresorbed or may undergo partial resorption followed byaddition of new cementum and embedding of collagenfiber.
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Developmental Anomalies :
Developmental and acquired anomalies
associated with cementogenesis
Enamel pro ject ion
Enamel pearl
Neop lasm of cementum
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Enamel pro ject ion
Focal apical extensions of thecoronal enamel beyond thenormally smooth cervical marginand on to the root of the tooth.If amelogenesis is not turned off before the start of
root formation, enamel may continue to form over
portions of the root normally covered by cementum
from odontogenic epithelium destined to form
Hertwigs root sheath. This may occur in localizedareas, particularly on the buccal aspects of lower
second molars.
Cl ifi i f C i l E l P j i
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Classification of Cervical Enamel Projections
Grade I: The enamel projection extends from the cementoenamel junction of thetooth toward the furcation entrance.Grade II: The enamel projection approaches the entrance to the furcation. It doesnot enter the furcation, therefore there is no horizontal component.Grade III: The enamel project actually extends horizontally into the furcation.
Masters DH, Hoskins SW: Projection of cervical enamel intomolar furcations. J Periodontal 1964;35:49.
Enamel pearl
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Enamel pearlEnameloma
Enamel Drop
They appear to form as a result of
localized failure of Hertwigs root
sheath to separate from the dentin
surface, thereby allowing the
cementogenesis to proceed.
Small, focal excessive mass of
enamel on the surfaces of the
tooth.
Th l b l f
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Cementicle
These are globular masses of
acellular cementum. Generally
less than 0.5 mm in diameter
which form within the PDL,
exhibit concentric appositional
layers of afibrillar or fibrillar
cementum and may be free within
PDL or becomes fused to radicular
cemental surface.
Neop lasm of cementum
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Neop lasm of cementum
CEMENTOMABENIGN CEMENTOBLASTOMA (True Cementoma)GIGANTIFORM CEMENTUMFOCAL CEMENTO OSSEOUS DYSPLASIA
CEMENTOMA
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Periapical Cemental Dysplasia,Periapical OsteofibromaOsteofibrosis Cementifying fibroma
Localized fibro-osteomaCementoblastoma
Periapical fibrous Dysplasia.
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I. Osteolytic phase
II. Cementoblastic phaseIII. Mature phase
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BENIGN CEMENTOBLASTOMA (True Cementoma):
The benign cementoblastoma is probably a true neoplasm of functional
cementoblasts which form a large mass of cementum or cementum like
tissue on the tooth root.
CLINICAL FEATURESMost frequently, under the age of 25 years with no significant sex
predilections. The mandibular first permanent molar is the most
frequently affected tooth. Other teeth involved have included
mandibular second and third molars. Mandibular bicuspids,
Maxillary bicuspids and first, second and third molars. Theassociated tooth is vital unless coincidentally involved. The lesion
is slow growing and may cause expansion of cortical plates of bone,
but is usually otherwise asymptomatic.
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GIGANTIFORM CEMENTUM
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GIGANTIFORM CEMENTUM
FOCAL CEMENTO OSSEOUS
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FOCAL CEMENTO OSSEOUS
DYSPLASIA
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DISEASES OF SYSTEMIC DISORDERS AFFECTINGCEMENTUMCLEIDOCRANIAL DYSPLASIA:Characterized by abnormalities of the skull, teeth jaws and
shoulder girdle and occasionally stunting of the longbones. Its most important oral findings is prolongedretention of deciduous teeth and subsequently delay ineruption of the succedaneous teeth. Sometimes, thisdelay in tooth eruption is permanent. The roots of theteeth are often some what short and thinner than usualand may be deformed.
A surprising and unexplained feature was the absence ofcellular cementum on the erupted teeth in both dentition,with no increased thickening of primary acellularcementum.
HYPERPITUITARISM
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Due to the hyperfunction of the anterior lobe of the pituitary gland.Hyperpituitarism in children involves generalized over growth of most
hard and soft tissues and called gigantism. Adult hyperpituitarism is
called Acromegaly. There is enlargement of jaws, macroglossia anterior
openbite, prognanthism. The root of posterior teeth enlarge as result of
hypercementosis. This may be the result of functional and structural
demands on teeth, instead of a secondary hormonal effect. Supraeruption
of the posterior teeth may occur in an attempt to compensate for the
growth of the mandible.
HYPOTHYROIDISM
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HYPOTHYROIDISM:
Result from insufficient secretion of thyroxin hormone. In children, it
may result in retarded mental & physical development. Base of the skullshows delayed ossification. Dental development is delayed and primary
teeth exfoliate slowly..
RADIOGRAPHIC FEATURE:
In children, it includes delayed closing of the epiphyses & skull sutures
effects on teeth include delayed eruption, short roots and thinning of
Laminadura. Patients with adult hypothyroidism show periodontal disease,
loss of teeth & resorption of the cementum.
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HYPOPARATHYROIDISM:
It is an uncommon condition in which, there is insufficientsecretion of parathyroid hormone. Clinical manifestation
includes carpopedal spasm. Some have sensory abnormalities
consisting of parasthesia and neurological changes. The
principle radiographic changes in calcification of the basal
ganglia. The jaws reveal enamel hypoplasia, delayed eruption,
external root resorption, root dilaceration.
HYPOPHASPHATASIA
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HYPOPHASPHATASIA:
Tonna, E. Factors (Aging) affecting bone and
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cementum. J. Perio., 42: 267; 1976.
Cementum apposition is continuous throughout life.Acellular cemental deposition at apical 1/3 .It accumulates in large quantities along the interradicularsurfaces of the tooth.Continual reapposition of new layers of cementum represents theaging of the tooth.Deposition appears to occur in response to functional stress, butmust be pointed out that layers of cementum are found at theroots of unerupted teeth of aged individuals.Often excementosis are formed leading to ankylosis with alveolarbone.Aging of acellular cementum is not readily discernedmicroscopically as compared to the cellular cementum, wherethere is degeneration and death of cementocytes .The cellular proliferative activity of cementum is low.
CEMENTUM RESORPTION
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Local causes:TFOOrthodontic movementPressure from malaligned
eruptive teethCysts and tumoursTeeth without functionalantagonistEmbedded teethReplanted and transplantedteethPeriapical diseasePeriodontal disease
Systemic causes:
Calcium deficiencyVitamin A,C D deficiencyHypothyroidismHeriditary fibrousosteodystrophyPagets disease
CEMENTUM RESORPTION
C t ti i i ll b lik iti i
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Cementum resorption appears microscopically as a bay like concavities in
the root surface.
Multinucleated giant cells and large mononuclear macrophages are
generally found adjacent to cementum undergoing active resorption.
Several sites of resorption may coalesce to form a large area of
destruction. The resorptive process may extend into the underlying dentin
and even into the pulp.
It is usually painless, the method by which resorption occur is similar tothat of bone. Accordingly, injury to the periodontal tissues affects the
cementoblasts. There are other pleuripotential cells of PDL which
differentiate into cementoclasts which participate in the resorption of the
more superficial cementum.
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Cementum resorption is not necessarilycontinuous and may alternate with periods ofrepair and deposition of new cementum. Thenewly formed cementum is demarcated fromthe root by a deeply staining irregular line,termed as Reversal line, which delineates theborder of previous resorption.
In most cases of repair there is a tendency toreestablish the former outline of the rootstructure. This is called anatomic repair.However, if only a thin layer of cementum isdeposited on the surface of a deep resorption,the root outline is not reconstructed and a baylike recess remains. In such areas some times itis restored by formation of bony projection sothat proper functional relationship will result.This is called functional repair.
CEMENTUM REPAIR
CEMENTUM REACTION TO PHYSIOLOGICAL TOOTH
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MOVEMENT & OCCLUSAL FORCES :
The distribution of cementum on impacted teeth tendsto indicate that, occlusal forces are not necessarily tostimulate cementum deposition. In posterior teethin the human cementum is markedly thicken on thedistal than on the mesial side due to mesial drift.
. The deposition of considerably more newcementum has been noted on the tension sidecompared with the pressure side of the root surfaceof teeth undergoing orthodontic tooth movement.
This finding correlates with oppositional layers ofbone lining the distal wall of alveolar socket &indicates that cementum like bone tissue has thepotential to be dynamically responsive and its
growth may be stimulated by tensional forces.
CALCULUS ATTACHMENT
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The first significant study on modes of calculus attachment was reported by
Zander in 1953 in which he described four types of attachment: A secondary cuticle interface between calculus and tooth structure.
Attachment of calculus matrix to irregularities of the cementum surface
corresponding to previous insertion locations of Sharpeys fibers.
Penetration of microbial organisms of calculus into cementum.
Attachment into areas of cementum resorption via mechanical locking into
undercuts.
Estimation of Individual Age Counting Years as Rings in
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ToothCementum
Conclusions :
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The periodontal tissues form a functional unit designed tomaintain tooth support and protection. In particular,cementum by virtue of its structural and dynamicqualities, provides tooth attachment and maintenance ofocclusal relationship. These multiple functions arefulfilled by the biological activity and reactivity ofcementoblast, which deposit two collagen containingvarieties of cementum with completely differentproperties.Unless disturbed, the cementum covering of the rootincreases in thickness throughout life. Albeit at a fasterrate apically than cervically.Root surface over time include changes in tooth position,resorption and repair, surface exposure to theenvironment, bacterial invasion and contamination, and
root caries.
The dynamic features of cementum are particularly
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highlighted by its repair potential.Irreversible damage may occur when the cementum surfacebecomes exposed to environment of a periodontal pocket, and theoral cavity.The interest in cementum has never been given up by researchers,and the ultimate goal of true periodontal regeneration aftertreatment for periodontitis has revived vigorously the interest in thisunique mineralised tissue. Knowledge about the differentiationmechanism of cementoprogenitor cells and the cell dynamics duringnormal development, repair and regeneration is not sufficient.
Basic Knowledge of cementum development during normalcy istherefore of utmost importance. Over recent years an increasingquantity of data has accumulated that allows the humancementogenesis to be described exclusively.
REFERENCES
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Carranza F.A., Newman M.G. :Clinical Periodontology, 8th Edition, 1996. Pg.36-40.
Newman Takei Carranza : Clinical Periodontology, 9th Edition, 2003. Pg.42- 45
Tencate A.R. : Oral Histology, Development, Structures and Function, 6th Edition,240-258.
Orbans Oral Histology and Embryology, 11th Edition, 175-197
Ramfjord S.P., Kerr D.A., Ash M.M.:World Work Shop in Periodontics, 1966. 43-44.
Schluger S., Yuodelis R.A., Page R.C.: Periodontal diseases, 2nd Edition, 1990.Pg.38-42.
Harrison J.W.: Intermediate Cementum, OS OM OP.1995: 79:624-633
Hammarstrom L.: Enamel matrix, Cementum development and Regeneration.J.C.P.1997:24:658-668.
Tencate A.R.: The development of the periodontium a largely ectomesenchymallyderived unit. P2000. 1997:13:9-19
MacNeil and Somerman : Development and Regeneration of Periodontium.Parallels and Contrasts. P2000.1999:19:8-20.
Genco, Goldman, Cohen: Contemporary periodontics. 6th Edition.
Grant Stern and Listgarten.
Goldman: Periodontal Therapy, 6th Edition.
Biology of the Periodontal Connective Tissue P Mark Bartold, A. SampathNarayan.
Oral Development & Histology: James K. Avery.
Colour Atlas of Oral Anatomy histology & embryology 2nd Edition B.K.BBerkovits.
Clinical Periodontology and Implant Dentistry 4th Edition Jan Lindhe.
Int. J.Dev.Biol.45:695-706
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