Endodontics L9: preparation of single rooted/straight root canals

Question 1

Q1: what are we trying to achieve when we clean and shape the root canal system? .

Answer 1

If there isn’t any periapical disease present then the purpose would be to maintain healthy periapical tissue, however if there is peri apical disease, the purpose would be to create an environment that will induce bone healing

Question 2

Q2: if we are preventing extrusion of necrotic debris, what are we doing?

Answer 2

We are preventing necrotic tissue being forced out of the apical foramen, to the apical tissue.

Question 3

Q3: what are the three main design objectives of endodontic treatment?

Answer 3

• Create a continuously tapering funnel shape
• Maintain apical foramen in original position
• Keep apical opening as small as possible (instrument to the apical constriction)

Question 4

Q4: where is the apical constriction located?

Answer 4

The apical constriction also known as the minor apical diameter, is located in the apical portion of the root canal having the narrowest diameter

Question 5

Q5: the matrix of dentin or other materials at the apical end of a root canal preparation that prevents further advancement or progression of both endodontic instruments and obturating materials is known as a what?

Answer 5

Apical stop

Question 6

Q6: what is the general rule when dealing with the instruments and material prior to a patient arriving?

Answer 6

Collect instruments and materials before patient arrives, but do not open.

Question 7

Q7: an endodontic mirror is a front-surface mirror. Why do we use this mirror instead of the standard one?

Answer 7

This mirror will not give a double image and is used for all endodontic procedures

Question 8

Q8: don not use instruments from the RCT kit until the tooth has been?

Answer 8

Isolated using rubber dam

Question 9

Q9: where must you not place your used endo files, and where would you place them?

Answer 9

You would not place the endo files on the bracket, but place them in the endo pot.

Question 10

Q10: an instrument will fail by torsion when the ultimate shear strength is exceeded, how does this occur?

Answer 10

Occurs when the tip or other part of the instrument binds to the canal wall, whereas the hand piece keeps rotating the instrument. Usually poor operator technique.

Question 11

Q11: flexural fracture/cyclical fatigue is caused by?

Answer 11

Continuous rotation in curved canals.

Question 12

Q12: if a fractured instrument is located in the apical third would you try to remove it?

Answer 12

Removal not practical without risk of damage

Question 13

Q12: if a fractured instrument is located in the middle/coronal third, what needs to be considered before you attempt to retrieve it?

Answer 13

If a straight line access is possible then yes, consider attempt to remove it.

Question 14

Q13: what are the advantages of using a variable taper file compared to a constant taper?

Answer 14

Each file preferentially cuts a certain part of the canal, much less likely to have the file stick in the canal (taper-lock) and fracture.

Question 15

Q14: the tooth length also described as ‘estimated working length’ is the measurement of the tooth from which regions?

Answer 15

From the incisal edge to radiographic apex.

Question 16

Q15: what would you use to irrigate the pulp chamber?

Answer 16

Sodium hypochlorite

Question 17

Q16: root canal preparation can be divided into stages and the first stage is coronal flare and initial negotiation. Which file is used to for the initial flaring of the canal orifice?

Answer 17

SX file

Question 18

Q17: what must you place on the steel flexofile, to ensure that you do not negotiate further than the working length?

Answer 18

A rubber stop

Question 19

Q18: what would the rpm and torque setting be on for the SX gold file?

Answer 19

Rpm 300, torque 4

Question 20

Q19: what is glyde?

Answer 20

A paste lubricant. Glyde is used to coat the stainless steel files.

Question 21

Q20: paste lubricants can only be used with which type of files?

Answer 21

Only stainless steel files, not rotary

Question 22

Q21: a working length can be determined by using which two ways?

Answer 22

Radiographically or electronic apex locator.

Question 23

Q22: canal preparation should end at which location of the canal?

Answer 23

The apical constriction

Question 24

Q23: how would you confirm apical patency?

Answer 24

By pushing the stainless steel file beyond the apical constriction.

Question 25

Q24: once we have established a apical patency and a glide path we must then go on to use rotary instruments to enhance the glide path. The pro glider instrument will be selected to do this, at which speed and torque would you be using this file at?

Answer 25

300 Rpm and torque 2.

Question 26

Q25: what four factors prevent passive movement of file?

Answer 26

1. Insufficient glide path,
2. Build-up of debris within the canal,
3. Build-up of debris on flutes of files,
4. Complicated root canal anatomy

Question 27

Q26: apical preparation is carried out to determine the diameter of the canal at the apical constriction, this is carried out using a process called?

Answer 27

Apical gauging.

Question 28

Q27: the finishing diameter of the file should be what, when compared to the apical constriction?

Answer 28

The diameter of the file should be equal to or bigger compared to the apical constriction.