endodontic instrumentation

Question 1

what are the principles of canal design?

Answer 1

tapering canal shape

small apical opening as possible

maintain apical foramen in same position

Question 2

which 2 ways can the canal be shaped?

Answer 2

chemical

• irrigation to clear smear layer and debris

mechanical

• use of hand and rotary instruments

Question 3

what are watch winding and balanced force?

Answer 3

watch winding is apical pressure with 90 degree winding motions clockwise and anticlockwise

balanced force is 1/4 turn clockwise, apical pressure, then 180 degrees anticlockwise

Question 4

what is the irrigation protocol after instrumentation?

Answer 4

EDTA 17% for 1 min

irrigate with 3% 30ml sodium hypochlorite for 10 mins. slow injection.

Question 5

what benefits over stainless steel does nickel-titanium have?

Answer 5

increased elasticity before deformation

increased cutting efficiency

more user friendly as fewer instruments and more simple sequences

Question 6

when would rotary instrumentation be used?

Answer 6

to gain straight-line access

Question 7

how are a glide path and straight-line access achieved?

Answer 7

small K file, and gates rotary to make straight-line access

Question 8

Outline process of using modified double flare technique

Answer 8

Access cavity and identify canal orifices

• check patency with size 10
• sequentially smaller gates glidden from 4 to 2 to coronal flare in straight portion of canal
• irrigate, recapitulate and check patency between each

Then apical flaring
- take WL measurement with K10 -1mm from red band
- at CWL: 15K, 20K, 25K (balanced force).
- irrigate, recapitulate and patency between each file
- apical gauge to ensure correct apical prep and GP wont extrude

Step back
- file size up from master file -1mm from CWL
- next size up -2mm
- next size -3mm
- master apical file in filing motion to smooth ledges