Endodontic Materials

Question 1

purpose of mechanical phase of chemomechanical disinfection

Answer 1

metal files are used to remove soft and hard tissues
this creates space for irrigants and creates the shape for obturation

Question 2

cyclic fatigue

Answer 2

freely rotating in a curvature seeing tension/compression cycle that leads to failure

Question 3

torsional fatigue

Answer 3

elastic and plastic limits exceeded. Bound area of an instrument doesn’t move whilst rest undergoes twisting/torsion force

Question 4

plastic deformation

Answer 4

permanent bond displacement occurring when elastic limit is exceeded

Question 5

plastic limit

Answer 5

point at which plastic is deformed - the file will break

Question 6

what is the benefit of stainless steel endodontic instruments undergoing work hardening

Answer 6

strengthens them
dislocations collect at grain boundaries

Question 7

Nitinol

Answer 7

also known as nickel titanium
equiatomic alloy of nickel and titanium
doesnt conform to traditional rules of metallurgy

Question 8

elastic deformation

Answer 8

reversible deformation that does not exceed elastic limit

Question 9

martensite vs austeritic form of NiTi

Answer 9

martensite form , seen at or below room temperature, soft and ductile material
austenite form - above 35 degrees celsius, strong and hard material

Question 10

what is meant by shape memory

Answer 10

material can be deformed at one temperature but when heated or cooled will return to its original shape

Question 11

taper

Answer 11

diameter changes along working length
usually large to small

Question 12

flute

Answer 12

groove to collect dentine and soft tissue

Question 13

purpose of leading/cutting edge

Answer 13

forms and deflects dentine chips

Question 14

land

Answer 14

surface extending between flutes

Question 15

relief

Answer 15

reduction in surface of land

Question 16

helix angle

Answer 16

angle citting axis forms with long axis of file

Question 17

name 3 purposes of endodontic irrigants

Answer 17

facilitate removal of debris
lubrication
kill bacteria and viruses
biofilm disruption

Question 18

why would chlorhexidine 0.3% be used in endodontics

Answer 18

to test dam integrity

Question 19

use of sodium hypochlorite 3% in endodontics

Answer 19

used as an irrigant for its antimicrobial function
however cannot remove smear layer

Question 20

use of EDTA 17% in endodontics

Answer 20

removes smear layer from root canal preparations