NICKEL TITANIUM INSTRUMENTS FOR ROOT CANAL PREPARATION

Question 1

taper

Answer 1

amount by which the diameter of an instrument increases from tip to handle

Question 2

tranditonal files

Answer 2

stainless steel

Standard shape ISO

Question 3

configurations of files

Answer 3

K files
Flexible K files
hedstrom

Question 4

K files

Answer 4

twisted wire to poduce flutes

Question 5

flexible K files

Answer 5

cross sectional design

SS or nickle titanium

Question 6

hedstrom files

Answer 6

grinded tapered blank

round in cross section

Question 7

technqiues to use K files

Answer 7

watchwind pull

balanced force

Question 8

hedstrom technique

Answer 8

up and down motion in passive canal

Question 9

disadvanategs of traditional files

Answer 9

produce narrow canal shapes
inflexible in larger sizes
may fracture
push pull can create ledges
aciton can push debris into the canal causing blockages

Question 10

NiTi

Answer 10

super elastic metal allou
flexible and shape memory
reduces potential for canal straightneing

Question 11

forms of NiTi

Answer 11

• martensite
• austenite

shape memory
can alter between these types and thus wont deform as mich

Question 12

radial lands

Answer 12

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

Question 13

rake angle

Answer 13

angle between the leading edge of the cutting tool and surface being cut

Question 14

issues with NiTi

Answer 14

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

Question 15

use of NiTi clinically

Answer 15

canal enlargemnt not canal negotiation

Question 16

protaper system

Answer 16

3 shapers
SX, 1 and 2 (1/2 for shaping coroanl, X for entrance)
3 finishers

variable taper
triangular cross section
active cutting blades

Question 17

contra indications for rotary instrumentation

Answer 17

• 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

Question 18

advanyages of NiTI

Answer 18

• 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