5. Fluid Dynamic
Study of fluid in motion & its subsequent effects on boundaries
Root canal irrigation is microscale ( microfluidics) flow of a liquid (irrigant) inside an
irregularly shaped domain of very small dimensions (root canal system).
Two ways for the Irrigants to reach all the pulp:-
1. Convection ………. flow developed during delivery (or during
agitation), In his way, chemically active particles (molecules/ions) are
transported quickly and efficiently by the fluid motion, that applies
forces on the targeted material ( mechanical effect ).
1. Diffusion………. The random movement of particles in a fluid
In areas of the root canal where a flow cannot be created,
irrigant transport by diffusion without mechanical effect .
6. Endodontic irrigation must achieve 4 aims
1- Efficient. Flow rate ………. To the full extent of the root canal system and subsequently to the
canal orifice, in order to:-
a) come in close contact with microorganisms/biofilm,
debris, and tissue remnants, carry them outside the canal
d) provide lubrication for the instruments.
2- Chemical Effects ……… Frequent refreshment of the irrigant, in order to retain a high
concentration of its active component(s) at the sites of interest
and compensate for their rapid consumption
(applicable only to chemically active irrigants).
3- Mechanical Effects ………. Application of force on the root canal wall (wall shear stress),
in order to detach/disrupt microorganisms/biofilm, debris,
and tissue remnants.
4- Safety …………….Restriction of the flow within the root canal system and prevention
of irrigant extrusion towards the periapical tissues.
7. Dr.Abdalazim Badraldin
SudaneseDentalCenter
Khartoum-Sudan
April. 2020
Three essential Components for
positive pressure irrigation
Leur Lock
Rubber stopper.. WL
Close ended with side
vented
Which syringe size ???
5 ml
P --- pressure developed inside syringe barrel
F --- tactile force applied to syringe plunger
A --- cross-section area of the syringe plunger
Variable capacities 20—1 ml
8. Dr.Abdalazim Badraldin
SudaneseDentalCenter
Khartoum-Sudan
April. 2020
Flow Rate directly proportional
Internal diameter of the needle
Pressure differences along the needle
Flow Rate inversely proportional
Viscosity of the irrigant
Length of the Needle
Factors determine the flow rates
9. Dr.Abdalazim Badraldin
SudaneseDentalCenter
Khartoum-Sudan
April. 2020
Flow Rate directly proportional
Internal diameter of the needle
Pressure differences along the needle
Flow Rate inversely proportional
Viscosity of the irrigant
Length of the Needle
Factors determine the flow rates
10. Dr.Abdalazim Badraldin
SudaneseDentalCenter
Khartoum-Sudan
April. 2020
Turbulent Flow Laminate Flow
Fluid moves in irregular paths or layers Fluid moves in smooth paths or layers
In endodontic lamina flow is recommended because it gives
steady constant flow rate and sufficient volume of irrigant .
In order to achieve lamina flow during canal irrigation ,the flow rate must be;-
0.01 mL/s steady lamina flow rate
0.26 mL/s unsteady lamina flow rate
o.53-0.79 mL/s turbulent flow rate
A high pressure can cause extrusion of the irrigant into
the periapical tissue (Hulsmann et al. 2009).
15. Dr.Abdalazim Badraldin
SudaneseDentalCenter
Khartoum-Sudan
April. 2020
Is the frictional forces occurring between the
flowing irrigant and canal walls.
Wall shear determines the mechanical effects,
because it detached material from the root canal wall.
In open-ended needles, an area of increased shear
stress is developed apically to the needle tip, in the
region of jet breakup.
closed-ended needles (side-vented and double-side-
vented) lead to almost twice as high maximum shear
stress, but limited near their tip, on the wall facing the
needle outlet .
The high wall shear stress around the needle tip,
for this reason it is recommended to move the
needle up and down along the canal wall
( longitudinal movement) and also in a rotation
movement in side vented closed ended needle.
16. Dr.Abdalazim Badraldin
SudaneseDentalCenter
Khartoum-Sudan
April. 2020
Jet
High – velocity fluid stream force out of a small – diameter opening
During needle irrigation the jet extends along the root canal,
apically to their tip, within a certain distance, which depends on :-
The shape of the root canal
The insertion depth of the needle
The flow rate,
The jet appears to break up gradually and
reverse flow towards the canal orifice .
In open-ended needles (flat, beveled,
notched), the jet is very intense .
In closed-ended needles are used (side vented,
double-side-vented), the jet is formed near the apical
side of the outlet (the one proximal to the tip for the
double-side-vented needle), and it is directed apically
with a slight divergence.
C. Boutsioukis and L.W.M. van der Sluis
Endodontic irrigation
19. Dr.Abdalazim Badraldin
SudaneseDentalCenter
Khartoum-Sudan
April. 2020
1- Dentinal tubules Disinfection
2- Apical Deltas Penetration
3- Biofilm removable
4- Isthmuses cleaning
Traditional needles irrigation fail to clean these areas,
this is why we need to activate the irrigant by creation of
Tsunami effect in order to push the irrigant to these areas