Midterm EP 2019

Question 1

What percentage of mechanical shaping and cleaning is done by rotary instruments?

Answer 1

65%. 35% of the canal is untouched, so the remaining 65% is cleaned and shaped

Question 2

Hedstrom is used for?

Answer 2

Filing

Question 3

Biological design objectives?

Answer 3

Minimum extrusion of debris

Question 4

What is the most appropriate way of using the barbed broach?

Answer 4

tissue removal

Question 5

Where are we most likely to see accessory canals?

Answer 5

Apical third

Question 6

What is the most effective way to prevent root canal obstruction during the instrumentation phase of an endo treatment?

Answer 6

copious irrigation

Question 7

What bacteria is most common in endodontic infections?

Answer 7

Enterococci

Question 8

What is the best technique to reach working length?

Answer 8

Watch winding

Question 9

What is the length of the actual cutting surface of a 25mm file?

Answer 9

16 mm

Question 10

What do preoperative radiographs in endodontics show you?

Answer 10

shape and size of the pulp chamber

Question 11

According to weine classification, what is the classification for 1 orifice to 2 canals?

Answer 11

Type IV

Question 12

Which tooth is most likely to have 2 canals?
Mx central
Md central
Mx canine
Md 1st premolar

Answer 12

md central

Question 13

Last step of access opening?

a) perforation
b) straight line access
c) deroofing
d) glide path

Answer 13

straight line access

Question 14

What is the landmark for working length?

Answer 14

minor apical constriction

Question 15

What causes cyclic fatigue?

Answer 15

it goes around a sharp curvature

Question 16

Which of these teeth would anticurvature filing on?
mand central
max central
max lateral
max 2nd molar
mand premolar

Answer 16

max 2nd molar

Question 17

What is the main disadvantage of the primary irrigant?

Answer 17

cytotoxicity

Question 18

What is the purpose of obturation?

Answer 18

prevention of the reinfection of the root canal system that has been chemo-mechanically disinfected

Question 19

Name and compare 2 methods of obturation and compare them? (6 marks)

Answer 19

Warm Vertical Compaction

advantages: single homogenous mass of obturation material, 3D obturation of the space, better filing of the lateral canals and irregularities.
disadvantages: difficulty in length control, possible increase of fracture risk with plugger compaction

Lateral Compaction: advantages: technically simple, does not require additional equipment.
disadvantages: non homogenous mass, increased sealer presence, increased possibility of leakage

Question 20

What are the standardized k file lengths? (3 marks)

Answer 20

21mm, 25mm, 31mm

Question 21

calculate the d5 for a 25.04 file? (4 marks)

Answer 21

25 is file so… 0.25+5(0.04) = 0.45 mm