Chemo-mechanical preparation

Question 1

Chemo-mechanical preparation:

what is the first step to be made as we want to begin chemo-mechanical preparation?

Answer 1

• estimate from the pre-op radiograph the approximate working length + length of the cure

Question 2

Chemo-mechanical preparation:

what is the coronal flare carried out with?

Answer 2

SX
S1
S2

Question 3

Chemo-mechanical preparation:

what motion are s files used in?

Answer 3

brushing motion

Question 4

Chemo-mechanical preparation:

how do protaper gold files cut?

Answer 4

cut on the outstroke

Question 5

Chemo-mechanical preparation:

having completed the coronal flare, it is important to work out the true length of the canal.

what is point b?

Answer 5

apical constriction

Question 6

Chemo-mechanical preparation:

what is the apical constriction?

Answer 6

point where we finish our obturation and instrumentation

Question 7

Chemo-mechanical preparation:

what is imporant about point e (radiographic apex)?

Answer 7

only bit whcih can be identified on a radiograph

Question 8

Chemo-mechanical preparation:

which point do we want to fill to?

Answer 8

b

Question 9

Chemo-mechanical preparation:

What has been located as radiographs are unreliable in endodontology?

Answer 9

apex locator

Question 9

Chemo-mechanical preparation:

why is it a problem that B’ is where we want to fill to and ‘E’ is the only point we can identify on a radiograph?

Answer 9

can damage constriction and lead to extrausion of irrignats, extrusion of obturation material

so just relying on radiographs alone doesnt give an accurate representation of where the apical constriction and foramen are

Question 10

Chemo-mechanical preparation:

how does the apex locator work?

Answer 10

electronic device that measures the diff in electrical characteristics between hard and soft tissues

the apical contriction is the junction point of the hard tissue of the root and soft tissue of the PDL

therefore the apex locator can identify that point exactly (cannot do anything else)

Question 11

Chemo-mechanical preparation:

once coronal flare has been completed, what size file do u pass thru the apex?

Answer 11

10/15 (depending on size of canal)

Question 12

Chemo-mechanical preparation:

once the file has gone through the apex, what are u going to do with the file?

Answer 12

going to gently rotate it and pull it back until the apex locator tells u that ur no longer through the apex

Question 13

Chemo-mechanical preparation:

what is meant by the ‘ zero reading ‘?

Answer 13

the transition point where the apex locator tells u that u are no longer through the apex

Question 14

What is the ‘zero reading’

Answer 14

the exit of the apical constriction, so junction between hard and soft tissues

Question 15

is the ‘zero reading’ the same as the working length?

Answer 15

no

Question 16

why is the ‘zero reading’ the same as the working length?

Answer 16

because if u work towards the zero reading u will damage and widen the constriction

Question 17

seeing as the ‘zero reading’ is not the same as the working length, what do we work towards (what is the WK)?

Answer 17

0.5mm short of the zero reading

Question 18

once we have established the zero reading from the apex locator, what do we confirm it with?

Answer 18

a radiograph

Question 19

after establishing the working length with the apex locator and radiograph, what is the next step?

Answer 19

• creating the apical glidepath to working length

Question 20

what size file do we use to create the apical glidepath?

Answer 20

size 10 then size 15

Question 21

Although we have been irrigating throughout the instrumentation phase, when does effective irrigation actually start?

Answer 21

after prepration is complete

Question 22

as syringe irrigation alone is not as effective, what method do we use instead?

Answer 22

manual dynamic irrigation

Question 23

what is the rate at which we irrigate?

Answer 23

15 burst -
at least 6-7 syringes

Question 24

how many syringes of irrigant do we use per canal?

Answer 24

at least 6-7 syringes

Question 25

when irrigating, what type of needle do we always need to use?

Answer 25

side vented

Question 26

list the stages and the files used when carrying out chemo-mechanical preparation

Answer 26

Question 27

explain how we use an apex locator

Answer 27