15. ACELLULAR AFIBRILLAR
CEMENTUM
During tooth eruption if there is loss of cervical part of
reduced enamel epithelium mature enamel cap come in
contact with surrounding connective tissue will deposit
a layer of acellular afibrillar cementum.
Contains neither cells nor extrinsic or intrinsic
collagen fibres except for mineralized ground
substance.
Coronal cementum
1-15 micrometer thickness
16. ACELLULAR EXTRINSIC
FIBRE CEMENTUM
Lacks cells
Bundles of sharpey’s fibres present
Found in the cervical third of root and extend apically
Thickness- 30 – 230 micrometre
Products of fibroblast and cementoblast
17. CELLULAR MIXED
STRATIFIED CEMENTUM
Composed of extrinsic and intrinsic fibres.
May contain cells
Appears in the apical third of the root and apices in the furcation areas
Thickness- 100- 1000 micrometre.
19. INTERMEDIATE CEMENTUM
Poorly defined zone near cementodentinal
junction of certain teeth that contain
cellular remnants of hertwigs sheath
embedded in calcific ground substance.
20. PERMEABILITY
Acellular and cellular cementum are very permeable and permit the
diffusion of dyes from the pulp and external root surface.
In cellular cementum the canaliculi in some areas are contiguos with
dentinal tubuli.
Permeability diminishes with age.
22. CEMENTODENTINAL
JUNCTION
• The terminal apical area of cementum where it joins the
internal root canal
• No increase or decrease in width with age
• Normal width 2-3 micrometre
23. THICKNESS OF
CEMENTUM
Cementum deposition is a continuos process.
Proceed at varying rates throughout life.
Most rapid formation at apical region to compensate eruption.
Thickness on the coronal half 16-60 micrometres
Apical one third and furcation- 150-200 micrometres.
Thicker on the distal surface than on the mesial (tooth tendency to
mesial drift)
From 11 to 70 years average thickness increases 3 times
Average thickness 95micrometer at age of 20yrs and 215micrometer at
age of 60yrs
24. HYPERCEMENTOSIS
Abnormal prominent thickening of the cementum with nodular
enlargement of apical third.
It can be diffuse or circumscribed.
Affect all teeth or may be confined to single tooth.
Age related phenomenon.
25. ETIOLOGY OF
HYPERCEMENTOSIS
• Local
Excessive tension from orthodontic appliances
Excessive tension from occlusal forces
Teeth without antagonist
Periapical irritation
Benign cementoblastoma
Cementifying fibroma
Periapical cemental dysplasia
Fibro cementoosseous dysplasia
26. • Systemic
Pagets disease
Acromegaly
Calcinosis
Rheumatic fever
Thyroid goiter
o Also oours as ageneralized thickening of cementum
without nodular enlargement ofapical third of root
o Also appear as cemental spikes
27. If overgrowth improves the functional qualities of the cementum it is
called cementum hypertrophy.
If overgrowth occurs in nonfunctional teeth or if it is not correlated with
increased function it is termed as hyperplasia.
It can also be seen as knob like projections- excementoses
28. RADIOGRAPHIC FEATURES
Radiographically radiolucent shadow Of PDL and radiopaque lamina
dura are seen in the outter border of area of hypercementosis
In cases of periapical cemental dysplasia ,condensing osteitis and
focal periaplical osteoporosis it can be differentiaited radiographically
as al these entities are located outside the shadow of PDL and lamina
dura
29. CEMENTUM RESORPTION
AND REPAIR
Permanent teeth do not undergo physiologic resorption the primary teeth.
Radiographically detectable resorption of root of permanent teeth occur
Causes
1.Local
2.systemic
30. CAUSES
local
trauma from occlusion
Orthodontic movement
Pressure from malaligned teeth
Cysts and tumors
Teeth without functional antagonist.
Embedded teeth
Reimplanted /transplanted teeth.
Periapical disease
Periodontal disease
32. CEMENTUM
RESORPTION
They appear microscopically like bay like concavities in root surface.
Multinucleated giant cells and large mononuclear macrophage are seen
nearby.
Several small areas of destruction coalesce to form large areas of destruction.
Resorption may extend to dentin and even pulp
33. Usually painless
May alter with periods of repair which produce reversal line
Cementum repair can occur in vital and non vital teeth (cementum
repair from external blood supply and not from pulp)
External blood supply includes from alveolar bone and periodontal
ligament and blood vessel.
34. REVERSAL LINE
• Newly formed cementum is demarcated from the root by
deeply staining irregular lines called reversal lines.
• It contains few collagen fibrils and ore proteoglycans and
mucopolysacchrides
• Embeded fibres of periodontal ligament reestablish
functional relationship with new cementum.
35. ANKYLOSIS
It is an abnormal repair
Fusion of cementum and alveolar bone with obliteration of periodontal
ligament.
Cause -
Chronic periapical infection
Tooth reimplantation
Occlusal trauma
Around embedded tooth
submerged
37. EXPOSURE OF CEMENTUM
TO ORAL CAVITY
Occurs due to recession
Cementum permeable to be penetrated by
organic substance
inorganic ions
Bacteria
Caries can also develop.
38. FUNCTIONS
• Attachment medium – binds tooth to the bone though sharpey’s fibres.
• Continous deposition
• Repairative tissue- it acts as a repairative organ.
• Functional adaptation- occlusal wear compensation
• Protect the dentin
• Help in eruption process
39. CONCLUSION
• Cementum is calcified avascular mesenchymal tissue that
covers anatomic portion of root. It provide anchorage to
principal fibers of PDL.It also plays a role in maintaining
occlusal relationship.Cementum when lose the protective
coveing of alveolar bone and gingiva, it get exposed to
oral environment ,bacterial penetration and thereby caries.
42. MCQ’S
1. Acellular cementum seen in
a) Coronal portion of root
b) Apical portion of root
c) Middle portion of root
d) At CEJ
2. Collagen fibres are absent in
a) AEFC
b) AAC
c) AMSC
d) Intermediate cementum
43. 3 . Edge to edge contact of cementum and enamel occur in
a) 10%
b) 30%
c) 50%
d) 5%
4. Sharpey’s fibres are derived from
a) Fibroblast
b) Cementoblast
c) Mesenchymal cells
d) osteoblast
44. 5. Feature of ankylosed teeth
a) Lack of physiologic mobility
b) Teeth in infra occlusion
c) Metallic sound
d) All the above
