Rotary files and Radiographic Interpretation

Question 1

what technique of taking radiographs is ideal?

Answer 1

Paralleling technique

Question 2

Describe Paralleling technique

Answer 2

Long axis and Root is perpendicular to the sensor

Question 3

Describe bisecting technique

Answer 3

Adjust cone/ source of radiograph

Question 4

SLOB rule

Answer 4

same lingual
opposite buccal

meaning if it moves opposite it is buccal to the other object

Question 5

a buccal object moves relative to? in what direction?

Answer 5

a buccal object moves relative to a lingual object

it moves in the SAME DIRECTION the x-ray beam is DIRECTED

Question 6

The x-ray beam can changed in what directions?

Answer 6

in a horizontal or a vertical direction

Question 7

what root will most likely always be longer on maxillary and mandibular first molars?

Answer 7

PALATAL (lingual)

Question 8

indications and advantages of cone shift for radiographs?

Answer 8

1. separation and superimposed canals
2. determination of working length
3. determiniation of curvature
4. determiniation of facial/lingual locations
5. movement of superimposed structures

Question 9

why does nickel titanium work the way it does? its two characteristics too

Answer 9

1. SHAPE MEMORY
2. SUPER-ELASTICITY

56% Nickel
44% titanium

Due to the transformations it goes through :
it has TWO CRYSTALINE PHASES/ STRUCTURES
1. Austensite
2. Maternsite

*goes through physical changes as we use it

Question 10

never put a rotary where?

Answer 10

WHERE A FILE HAS NOT GONE

Question 11

Stress-strain relationship

Answer 11

stress increases? the strain will increase as well at an exponential rate

Question 12

elastic limit

- describe what is seen?

Answer 12

permanent deformation occurs here

Question 13

difference between stainless steel and NiTi in terms of stress-strain relationship

Answer 13

larger range of stress you can put on it before it becomes elastic deformation
- then will also eventually get plastic deformation – then fracture

Question 14

plastic deformation characteritstic?

Answer 14

comes after the elastic limit (permanent deformation)

Fracture limit – will break

Question 15

shaping ability of rotary vs SS hand instruments?

Answer 15

studies have shown that in extracted human teeth, rNiTi maintains the original canal curvature better than SS hand instruments
- especially in the apical region of the root canal

• studies have shown that NiTi is significantly better than SS when the apical region was enlarged > 30

Question 16

percentage of canal dentin that is untouched, regardless of instrument type?

Answer 16

35%

Question 17

Cleaning ability of NiTi rotary?

Answer 17

Most CANNOT completely clean and instrument the root canal system so it reinforces the importance of antibacterial IRRIGATION for disinfection of the canal system

Question 18

working time with rotary?

Answer 18

dependent upon the operator factors and the preparation technique rather than the instrument type

Question 19

two types of fatigue that occurs?

Answer 19

1. torsional fatigue

2. cyclic fatigue

Question 20

definition of cyclic fatigue

Answer 20

continuous rotations around a curvature result in repeated expansion- compression cycles that lead to metal fatigue and fracture

rotation in curved canals will bend instruments once per rotation, which ultimately will lead to work hardening and brittle fracture – known as cyclic fatigue

Question 21

definition of torisional fatigue failure

Answer 21

friction or holding the tip while the remainder continues to turn past the plastic limit

Question 22

common rotary file usage problems

Answer 22

1. too much pressure on the handpiece
2. inconsistent RPM
3. not doing a “crown down” technique (need to be open coronally first with these so they can work in the lower parts of the canal)

Question 23

minimum file you need to use for glide path before rotary use?

Answer 23

20 file

Question 24

first three rotary files used

color and size with taper

Answer 24

SX - shaper X
0.19 / .04

S1 - purple (like the 10 or 12)
0.18 / .02 taper

S2 - white (like the 15)
.20 / .04 taper

Question 25

describe protaper gold shaping files

Answer 25

pre-enlarged canals and are designed to be used with the same familiar outstroke brushing technique

Question 26

after shaping rotary files what are the next three?

color? size? taper?`

Answer 26

Finishing files

Yellow - like a #20
.20 with .07

red - like a number 25
0.25 / .08

blue - like a number 30
.30 / .09

Question 27

describe the finishing files

Answer 27

provide the trusted deep shapes that promote 3D cleaning and filing root canal systems

• afteryou use the shaping ones these will do the middle and APICAL more

Question 28

what comes after blue in the rotary files? sizes?

Answer 28

black with black and black with double yellow bands

black is a 40 and black with yellow is a 50

Question 29

what is the color order of ISO files?

Answer 29

purple 
white 
yellow
red 
blue 
green 
black 

if go past that black repeats the color scheme starting at white

Question 30

difference in size percentage wise going from a #10 to a #15 file?

Answer 30

50 % larger

Question 31

non cutting edge of a file is called what?

Answer 31

the land

Question 32

which file stays centered in the canal better?

Answer 32

the one with more land

Question 33

where does the S1 file cut?

Answer 33

coronally

Question 34

where does S2 cut?

Answer 34

in the middle portion of the canal

Question 35

where do the F files cut?

Answer 35

apically

Question 36

when you get to working lenght do you use rotational movements anymore with the files?

Answer 36

no - push pull motion now

Question 37

if you do not use a pre-curved file what could happen?

Answer 37

1. apical perforation
2. ledge formation
3. apical blockage

Question 38

S1 size at top and bottom

Answer 38

top - 1.2 mm

bottom - .17 mm

Question 39

S2 size at top and bottom

Answer 39

top - 1.2

bottom - .20

Question 40

how long should rotaries be at length for?

Answer 40

no more than one second!!!

Question 41

what has more fatigue thick or thin?

Answer 41

thicker

so more diameter can tolerate less cyclic fatigue

Question 42

when do you apical gauge?

Answer 42

After F1 (yellow rotary - which corresponds to #20 file)

yellow is a .07 taper with a tip diameter of .20

Question 43

what do you use to apical gauge? what are you trying to determine?

Answer 43

use hand files that have a .02 taper in them

trying to determine the diameter of the apex