9. Root Canal Instrumentation

Question 1

what is meant by cleaning/disinfecting?

Answer 1

removal of organic pulp debris, microorganisms and tooxins

Question 2

what is meant by shaping?

Answer 2

controlled removal dentine to produce a tapering shape that can be disinfected and sealed throughout its length with a root canal filling

Question 3

what are the biological objectives of endodontic treatment?

Answer 3

• confine instrumentation to the root canal
• prevent extrusion of necrotic debris
• remove all tissue debris and substrate for bacterial regrowth
• create sufficient space for irrigation and intracanal medication
• complete cleaning and shaping in one visit if possible

Question 4

what are the design objectives of endodontic treatment?

Answer 4

• 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 5

what are the instruments and materials needed for prep for RCT?

Answer 5

• examination kiy
• LA kit
• Handpieces and appropriate burs
• Rubber dam kit, floss, dam, liquid dam, sponge
• RCT kit, paste lubricant (Glyde)
• X2 irrigating syringes/needles
• X2 galley pots
• Irrigants (Sodium hypochlorite , citric acid)
• endodontic instrument kit

Question 6

what type of mirror is used for endo and why?

Answer 6

front surface mirror - as this will not give you a double image

Question 7

why use a rubber dam?

Answer 7

to get an aseptic technique - excludes contamination with oral microbes including organisms that ahve a greater resistance to treatment than members of the ‘normal’ root canal microbia
- facultative anaerobes
- yeasts - candida albicans

Question 8

what is an endoblock used for?

Answer 8

to measure the length of files

Question 9

where should you place dirty used files?

Answer 9

onto an endopot - NOT the bracket tray

Question 10

what material type of file would you use initially for the root canal?

Answer 10

stainless steel

Question 11

what were the drawbacks of conventional hand stainless steel preparation techniques?

Answer 11

• mishaps (ledges, canal blockage, zipping of foramen)
• debris extrusion with filing motion
• time consuming
• less predictable shapes in curves canals

Question 12

when would you use the balances force technqiue?

Answer 12

when the canal is too wide to be shaved with pro taper gold files

Question 13

describe the balanced force technique

Answer 13

• engage dentine with a light quarter clockwise turn (60 degrees)
• the cutting stroke - half turn anticlock wise, with apical pressure
• clearing cutting debris requires another light quarter clockwise turn of 60 degrees

Question 14

what are the advantages of the rotary NiTi techniques?

Answer 14

• less canal transportation
• less debris extrusion (less post op pain)
• faster than hand prep
• more predicatable results

Question 15

what are the goals of contemporary root canal shaping?

Answer 15

• mechanically removes pulp tissue, microorganism and infected dentine
• creates space for effective irrigation and disinfection
• creates space for placement of a root canal filling

Question 16

you dont use niti files with slow-speed handpieces, what do you use them with instead?

Answer 16

endodontic motors

Question 17

what is torque?

Answer 17

a rotational force that measures how much a force causes an object to rotate

Question 18

would you use a high or low torque value for a high/larger more tapered file?

Answer 18

higher torque

Question 19

what type of material is protapers gold?

Answer 19

nickle titanium (NiTi)

Question 20

What values would you want to have when using protaper gold files?

Answer 20

300rpm, and torque of 4

Question 21

what factors can contribute to instrument fractures?

Answer 21

• the operator
• instrumentation technique
• instrument design
• use of torque controlled motors
• rotational speed
• canal geometry - angle of curvature
• number of uses

Question 22

what is the most common reason for an instrument to fracture?

Answer 22

torsional fracture/sheer fracture
- when the instrument fails by torsion when the ultimate shear strength is exceeded
- occurs when the tip or other part of the instrument binds to the canal wall but the hand piece keeps rotating

Question 23

what is the advantage of the protaper universal to other NiTi file designs?

Answer 23

the variable taper design - the taper of the file changes along its length and is different for each file in the sequence
advantages
- each file preferentially cuts a certain part of the canal
- much less likely to have the file stick in the canal and fracture

Question 24

what files are involves in the protaper gold system?
3 shaping files
5 finishing files