NICKEL TITANIUM INSTRUMENTS FOR ROOT CANAL PREPARATION Flashcards
taper
amount by which the diameter of an instrument increases from tip to handle
tranditonal files
stainless steel
Standard shape ISO
configurations of files
K files
Flexible K files
hedstrom
K files
twisted wire to poduce flutes
flexible K files
cross sectional design
SS or nickle titanium
hedstrom files
grinded tapered blank
round in cross section
technqiues to use K files
watchwind pull
balanced force
hedstrom technique
up and down motion in passive canal
disadvanategs of traditional files
produce narrow canal shapes inflexible in larger sizes may fracture push pull can create ledges aciton can push debris into the canal causing blockages
NiTi
super elastic metal allou
flexible and shape memory
reduces potential for canal straightneing
forms of NiTi
- martensite
- austenite
shape memory
can alter between these types and thus wont deform as mich
radial lands
flat area which prevents file from locking into dentine
cutting occurs through a planeing action ie passive
some do not have these lands - active cuttign
rake angle
angle between the leading edge of the cutting tool and surface being cut
issues with NiTi
can produce a thicker smear layer
particularly in 1/3 apical
- torsional failure caused by unwinding of the file usually as a result of too much apical force during instrumentation
- flexural fatigue results from repeated flexing usually from use in overly curved canals (inc danger in the S shaped canals)
- torsional failures are more common than flexural failures
use of NiTi clinically
canal enlargemnt not canal negotiation
protaper system
3 shapers
SX, 1 and 2 (1/2 for shaping coroanl, X for entrance)
3 finishers
variable taper
triangular cross section
active cutting blades
contra indications for rotary instrumentation
- tight or sclerosed canals (once glide path obtained can use rotary)
- vey curved canals (need to be careful and have a glide path
- S shaped canals
- apical hooks
- canals with sharp elbows (very acute angle)
- if a glide path cannot be formed
advanyages of NiTI
- less canal transportation(follow the shape better)
- flexible therefore better at preparing curved canals
- good deep shape
- less debris extrusion
- faster than traditional files
- fewer files used
- more predictable results