SS and NiTi in endo

Question 1

what is the ISO specification for dentistry

Answer 1

ISO 3630-1, 2019

Question 2

Types of instruments

Answer 2

standard instrument (taper 0.2)
taper instrument (uniform taper)
non taper instrument (cylindrical)
variable taper (more than one taper in working part)
shape instrument (contoured working part)

Question 3

what is a hedstrom file

Answer 3

only cuts on retraction

Question 4

temperature dependant phases of NiTi

Answer 4

austenitic - high temp
martensite - low temp
r-phase - intermediate temp

Question 5

what phase is niti file in the canal

Answer 5

martensitic

Question 6

what phase is niti file when removed from canal

Answer 6

austenitic

Question 7

how are niti files manufactured

Answer 7

from niti wire

Question 8

examples of 5th gen niti files (2013)

Answer 8

wave one gold
protaper next
reciproc blue

Question 9

what is the standard taper

Answer 9

0.02

Question 10

describe the taper on a taper instrument

Answer 10

uniform taper

Question 11

what shape is non taper instrument

Answer 11

cylindrical

Question 12

what is variable taper

Answer 12

more than one taper in working part

Question 13

what part of the endodontic instrument is the cutting surface?

Answer 13

working part

Question 14

what part of the endodontic instrument is the part that fits in the handpiece?

Answer 14

shank

Question 15

what part of the endodontic instrument is from the tip to the handle/ shank?

Answer 15

operative part

Question 16

what type of protaper files have a non active tip?

Answer 16

protaper universal

Question 17

what type of protaper file has an active tip?

Answer 17

protaper retreatment

Question 18

what do you call the cutting angle?

Answer 18

effective rake angle

Question 19

what is stiffer: NiTi or SS?

Answer 19

SS

Question 20

what is more flexible: NiTi or SS?

Answer 20

NiTi

Question 21

how are SS Hedstrom files manufactured?

Answer 21

microgrinding

Question 22

how are SS Kfiles/ reamers manufactured?

Answer 22

from raw ss wire. ground then twisted counter-clockwise

Question 23

what is cheaper: ss or NiTi?

Answer 23

SS

Question 24

describe memory shape

Answer 24

the file keeps martensitic phase when stress causes permanent deformation
if heated again, it will return to original austenitic phase

Question 25

what is more brittle: martensitic or austenitic?

Answer 25

martensitic

Question 26

what has a higher modulus of elasticity: austenitic or martensitic?

Answer 26

austenitic

Question 27

how does austenite transform to martensite?

Answer 27

stress or heat

Question 28

explain superelasticity of NiTi files

Answer 28

file changes from austenitic to martensitic when inserted into canal as soon as it is removed from the canal it returns to austenitic

Question 29

explain memory shape

Answer 29

if the temperature that the file is under is stable for the martensitic phase, the stress causes permanent transformation the file would need to be heated again to return to an austenitic phase