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Cleaning and shaping of root canal system.

المفصولين االسبوع الجاي رح تطلع اول مجموعة من طالب الدفعة

Today we will talk about root canal preparation or chemo-mechanical preparation of root

canal system

Q > why do we need to prepare the root canal system? “For what purpose “

for a biological region which is , to remove all tissue and necrotic debris from the root canal

system .

Q> how to clean it?

We can clean the canal by chemical means using irrigation

solution and by mechanical mean using files in order to remove

all necrotic tissues .

Those surface which won’t reached by these files, like accessory

canals throughout main root canals . For example, in molars, we

have 3-4 root canals and still we have accessory canals in the

furcation area or on the lateral side of the canal >> so we will

use irrigate solution or chemical solution.

Instruction while working

*Each root canal is unique, it’s different form the adjacent

canal , from adjacent root and from canal of adjacent tooth .

*while cleaning we need to maintain the shape of the canal as

it’s is , we shouldn’t change the internal shape of the canal by

over widening , so conical shape canal won’t become

rectangular.

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*we shouldn’t go beyond the apex .

Correct the 3rd status in the slide : the apical

constriction not position

* The apical constriction should be maintained >> apical

constriction: it’s dentin-centum junction in the apical part

which is away from the anatomical apex by 0.5 to 1.5 mm.

*Don’t’ over prepare the apical opening, we need an apical stop ( it’s where my gattaparka will

set )

*You need not to force the necrotic tissue beyond the anatomy of the apical apex

*try to complete cleaning and shaping in one visit , if u clean one canal and leave others for

next visit , root canal system will be still infected .

Slide 5

It’s the original shape of the canal , and after

preparation we need to maintain the same shape.

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This tooth has a lateral canal in the

furcation area which causes this defect,

so we clean it using irrigant solution

then seals it by our obturation and

sealers.

Irrigant

*they should be antimicrobial.

*without irrigant we will be able to clean only 2-40% of

canal ( using it will clean 60% of canal )

Q> why we need them?

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1- To flush out debries

2- - to be anti microbial

3- To dissolve organic material in pulp tissues and dentine

4- Act as lubricant for our instrument

Common irrigant

Sodium hypochloride – hydrogen peroxide – chelating

agent (EDTA) – saline – local anesthesia – iodine –

cholorohexidine

Dr. leave advantages And disadvantage in slide (1o-11) and focused on table on the slide 12

*This is different type of solutions and its main function.

*E ficals : I’s common bacteria in root canal system

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*If we combine sodium hypo chloride and cholorohexidine we will have an ideal irrigant

solution.

*the most common solutions nowadays: sodium hypo chloride and cholorohexidine

Stages in cleaning and shaping in root canal

system

1- Make coronal flare (widening ) and make strait line

axis using gates Glidden .

2- Establish our working length

3- Apical preparation

Step 1

Q > why do we need to prepare the coronal portion?

1- We need to remove obstructions to be able to go

straight all the way down to the apex ,

So preparing the canal more efficiently .

*Most effected tissue is in the coronal portion > so

we need to get rid of them

2- allow us to irrigate the canal more efficiently

and to allow the solution to go out

3- give the straight line access to the canal

>>> more accurate length determination

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*From the 1st lecture I have mention the gate

Glidden which is numbered from 1 to 6 and they

are used for coronal flare.

*We begin our work form the large size to the

smaller.

*in this case , we use size number 5 to the coronal

part then go down to use size number 1 or 2

* Number 1 is easy breakable and so we usually avoided unless we have very tiny canal

and we need to negotiate the orifice of that canal .

* we use it in reaching the first of the curvature , we don’t go beyond the curvature

point ( means : one the canal start to tend right or left we stop the instrument >>

means also , we only work form this curvature point to the coronal part “UP” ) ,

otherwise if you continue , you will perforate the canal .

stage 2 , determining the working length (slides from 18 – 22 )

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you can see the apical constriction and the anatomical apex , the difference between them is

around 2 mm .

Remember , the master apical file is the last file which you use in widening the apical

part but in our book , it’s mentioned that the master apical file is the largest file which

reaches the full working length and slightly bend .

*After we prepare the apical enlargement, we use the final apical file , and according to

that we use the gatta parch point for obturation .

* according to our book , the smallest file that you can take A radiograph with in

determining the working length is 20 , in other reference , they says : 15

We should follow our book

If there is a part of the coronal portion which

is not opened well, we need to go far away

from the apex .

Means: look to this red area , there is a

different between stage (2) and (3) = 1 or 2

mm >> in order to make a straight line access

you had to change ur file working direction

as in stage (3)

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stage 3

preparation of the canal : ( step back process)

1- we insert the master apical file to the full working length ,( we select this file and it should

be loose )

2- Then increasing the file size gradually until 4 to 6 sizes “ usually “ To make the apical

enlargement but with 1mm. shorter than the full working length ( this is called : re-

capitulations )

Ex: if ur master file was 25 and the full working length was 20mm , the next file is 30 with

length = 19mm .

3-irrigate the canal.

4-re – work the steps again until we reach the curvature (above it we use gateglliden)

Q > why do you think we re- insert the master file again and re-use irrigation again ?

Because while working Ur are condensing the debris in the apical part, so we will end with

loosing Ur working length.

Q> Why we don’t we make all file with one length ? >> Why we are reducing the full

working length?

Logically, the canal is wide coronally and narrow apically, so if we keep increasing the file size

without reducing W.L we will end up with too much preparation and we will break the apex .

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DON’T’ GET CONSFUSED Last week we make an apical preparation which is 2- 4 sizes

more than the file with F.W.L , the last one u use in apical enlargement , we start using it in

the step back process.

A student asks: how should we know that we reach the curvature?

From the pre -radiograph we can estimate the full working length and we can know the

anatomy “starting point of our curvature “of the root And how many canal we have .Also

while inserting file , u can feel the increment in resistant.

Slides: 25-27 >> this is an apical enlargement . same W.L but increasing the in file

size

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Slides 28 – 33:step back process increasing the file size and decreasing 1mm from W.L

Slides 34-36 > important

Notices

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When u insert the file inside the canal ,this is passive

motion (it’s not cutting dentine) , but when u pull it out , it

will be in active motion (cut dentine )

you rotate the file clockwise and half a tern anticlockwise

then you pull it out , when you do that it shapes the

dentine wall > so prevent packing of dentine debris in the

apical part and you maintain ur working length

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*Missing irrigation may end with losing ur W.L

* In stepping back, don’t try to jump two sizes in order to finish earlier because you will have

large step and a part that isn’t prepared.

Dr. said that slides alone are not enough

Forgive me for any mistake .

MADE BY : FARAH SALEM

Moments in our life may not come back again so live as it’s the last moment in

Ur life .

Thanks for who make me feel what moments of happiness mean