Cellular elements - PowerPoint Presentation

Slide1

Cellular elements

Types - connective tissue cells (

Fb

,

Cb

, Ob)

- epithelial rest cells

-immune system cells

- cells associated with neurovascular elementsSlide2

Connective tissue cells

Fibroblast-

- most common cells in the

PDl

- ovoid or elongated cells and exhibit pseudopodia like process

- synthesize collagen and have the capacity to

phagocytose

old collagen fib and degrade them by enzyme hydrolysis.Slide3

Cementoblast

- They are the cells responsible for secreting the organic matrix of

cementum

in the PDL.

Osteoblast

- They are found on the surface of the alveolar bone. Slide4

Epithelial rest cells

Epithelial rest of

Malassez

are considered as remnants

Hertwigs

root sheath which disintegrates during root development.

Most numerous in apical and cervical areas.

when stimulated, may participate in the formation of

periapical

cyst and lateral root cyst.Slide5

Immune system cells

Include –

neutrophils

, lymphocytes, macrophages, mast cells and

eosinophils

.

These cells as well as those associated with neurovascular elements, are similar to the cells in other connective tissues.Slide6

Ground substance

GAG (

glycosaminoglycans

)

-

Hyaluronic

acid

-

Proteoglycans

GP (

glycoproteins

) - fibronectin - LamininWater (70%)Slide7

Functions of ground substance

Helps in transportation of water, electrolyte, nutrients, and metabolites, to and from CT cells, thus is essential for the maintenance of the normal function of CT.Slide8

PDL may also contain calcified masses called

cementicles

which are adherent to detached from root surface.

Cementicles

may develop from calcified epithelial rest, around small

spicules

of

cementum

or alveolar bone traumatically displaced in to PDL, from calcified

sharpey’s

fib, and from calcified

thrombossed

vessels in PDL.Slide9

Functions of PDL

Physical

Formative

Remodelling

Nutritional

Sensory Slide10

Physical function

Provision of soft tissue “casing” to protect the vessel and nerves from injury to mechanical forces.

2. Transmission of

occlusal

forces to the bone.

3. Maintenance of gingival tissues in their proper relationship to the teeth.

4. Resistance to the impact of

occlusal

forces (shock absorption).Slide11

SHOCK ABSORPTION

2 theories-

-Tensional theory

-

Viscoelastic

system theorySlide12

Formative and remodeling function

PDL have the regenerative capacity in providing the cell lineage namely ob,

cb

and

fb

. Thus it help in the formation and

resorption

of

cementum

and bone during physiological tooth movement and repair of injuries.Slide13

Nutritional and sensory function

PDL supplies nutrients to the

cementum

, bone and gingiva by way of blood

vs

and also provide lymphatic drainage.

The PDL is abundantly supplied with sensory nerve fib capable of transmitting tactile, pressure and pain sensations by the trigeminal pathway.Slide14

There are 4 types of neural terminations are present in PDL

Free ending-

which have tree like configuration and carry pain sensation

Ruffinian

corpuscles-

Mechanoreceptors (in apical areas)

Meisners

corpuscles-

Mechanoreceptors (in

midroot

areas)

Spindle like receptors- Pressure and vibration receptors/Slide15

Homeostasis

With the presence of both formative and

resorptive

activity the PDL provides a homeostasis in the tissue environment.Slide16

Blood supply

3 sources-

1. Apical

vs

2. penetrating

vs

from alveolar bone

3.

Anastomosing

vs

from gingiva

Maxilla - sup

alv

artery

mandibli

-

inf

alv

artery

Venous drainage of PDL accompanies the arterial supply.Slide17

Nerve supply

1. Anatomic

2. Sensory Slide18

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