endo Flashcards
what are herbert schilder design objectives (3)
continuously tapering funnel shape
maintain apical foramen in original position
keep apical opening as small as possible
5 file motions
filing
reaming
watch winding
balanced force
envelope of motion
what technique can be described as back and forward oscillation of 30-60 degrees with light apical pressure
watch winding technique
when would you use the watch winding technique
useful when passing small files through canals
what technique can be described as
Engage clockwise into dentine ¼ turn (90 degrees)
With continued pressure go counterclockwise ½ turn to strip the dentine away (180
degrees)
Perform 1-3 times before removing debris
balanced force
2 benefits of true reciprocation
Mimics manual movement
Reduces risks associated with continuously rotating a file through canal curvatures
two ways an instrument can fail
cyclic fatigue
torsional fatigue
describe cyclic fatigue
file freely rotating in curve
generation of tension and compression cycles leading to failure
cross section of recriproc
s shape
non cutting tip
what are the degrees of turning for reciproc
150 counter - cutting
30 clockwise
after estimating EWL - what fraction of working length do you set stopper
2/3 of EWL
why should you remove reciproc after 3 pecks and only peck 3mm
to clean - as wont work adequately
what instrument do you used for WL determination
ISO size 10
define gradual curvature of root canal
If a hand instrument size 10 goes to working length even in radiographically strongly
curved root canals without being pre-curved the curvature is classified as gradual
when can you finish WL prep with R25 and when should you finish with hand instruments
finish with R25 if ISO 15 goes to working length without being pre-curved
if not finish with hand
