Root Canal

Question 1

Steps to a root canal:

Answer 1

1) Access prep
2) Cleaning and shaping
3) Filling/obturation

Question 2

cause of primary vs secondary endodontic infection

Answer 2

Primary- bacteroides (gram negative obligate anaerobe)

Secondary- Enterococcis faecalis

Question 3

most important step of RCT for technique

Answer 3

access

Question 4

shape of access for incisors

Answer 4

triangular or ovoid on lingual surface

Question 5

shape of access for canines

Answer 5

ovoid

Question 6

shape of access for premolars

Answer 6

ovoid (narrow)

Question 7

shape of access for maxillary molars

Answer 7

4 canals (2 in MB root) –> blunted triangle/rhomboidal

3 canals –> triangular

Question 8

shape of access for mandibular molars

Answer 8

4 canals (2 canals/root) –> rectangular

3 canals (more common, 2 canals in D root) –> trapezoidal

Question 9

Which premolar is the most common to have two roots and two canals?

Answer 9

maxillary 1st premolar

Question 10

How far is WL from the apex?

Answer 10

0-2 mm

Question 11

What is this method of cleaning and shaping?
Shape the coronal third –> apical third –> middle third (small to big) usually using hand instruments
Shaping the coronal third allows access for a file to reach the apical third, at which the operator can then shape from apical to coronal

Answer 11

Step-back

Question 12

What is this method of cleaning and shaping?
Coronal –> apical direction usually using rotary instruments (use progressively smaller files as you reach more apical, change files when you feel resistance)

Answer 12

Crown-down

Question 13

refers to filling and sealing the cleaned and shaped canal system

Answer 13

obturation

Question 14

2 obturation materials

Answer 14

gutta percha filler + ZOE sealant

Question 15

Name the obturation technique: Using a finger spreader for placement of multiple gutta percha cones to WL until spreader can no longer penetrate the coronal part of the canal

Answer 15

cold lateral

Question 16

Name the obturation technique: seating gutta percha cone to WL and using a heated plugger instrument to compress the gutta percha

Answer 16

warm vertical

Question 17

instruments with a 0.04mm or 0.06 mm taper, uses an electric handpiece that rotates according to RPM

Answer 17

NiTi rotary instruments

Question 18

taper of SS hand files

Answer 18

0.02mm

Question 19

ISO color coding for SS hand files from small –> large

Answer 19

pink, grey, purple, white, yellow, red, blue, green, black

Question 20

SS hand files that are twisted-square in cross section, rotate clockwise –> counterclockwise

Answer 20

K-files (Kerr)

Question 21

SS hand files that have spiral grooves, aggressive, cuts in retraction

Answer 21

H-files (Hedstrom)

Question 22

drill used to open 1/3 of canal for straight line access

Answer 22

Gates-Glidden drill

Question 23

hand file with a twisted-triangle cross section, rotated clockwise

Answer 23

reamer

Question 24

hand file used to remove entangled and difficult to remove substances

Answer 24

barded broaches

Question 25

formula for file diameter

Answer 25

D0 + (# mm from tip) (taper)

Question 26

irrigant that dissolves tissue (organic matter) and is antibacterial

Answer 26

sodium hypochlorite (NaOCl)

Question 27

irrigant that dissolves inorganic material (smear layer) and lubricates

Answer 27

EDTA

Question 28

irrigant used in re-treatment to dissolve gutta percha

Answer 28

choloform

Question 29

when a pathway is created and allows communication between the root canal and periodontium

Answer 29

perforation

Question 30

Signs of perforation:

Answer 30

- sudden pain - immediate hemorrhage

Question 31

tx for a perforation

Answer 31

internal repair with MTA

Question 32

Possible perforation locations:

Answer 32

Furcal- through pulp floor Coronal- through the crown Strip- from too much coronal flaring Root- through root surface

Question 33

common location for strip perfs to occur

Answer 33

mandibular molars, distal surface of the mesial root (mesial side of mandibular molars has thicker dentin, so always favor this side)

Question 34

For a root perforation, there is a better prognosis the more _______ the perforation is.

Answer 34

apical

Question 35

an irregularity created by the operator on the root canal wall, occurs when the original pathway of canal is lost during instrumentation

Answer 35

ledges

Question 36

Ledges often occur in ________ and ________ diameter canals.

Answer 36

longer / smaller diameter

Question 37

Files naturally tend to straighten out in curved canals, hence _______ files are less likely to create ledges due to their flexibility.

Answer 37

NiTi

Question 38

bypassing the ledge by using a smaller instrument/file

Answer 38

renegotiation

Question 39

when an instrument breaks and remains within the canal

Answer 39

instrument separation

Question 40

Reasons why instrument separation might occur:

Answer 40

- inadequate irrigation to allow instrument to move in and out - files are too big and get lodged in canal - used, weak files and more prone to fracture - flexible NiTi files more prone to fracture

Question 41

The _______ the complication/error occurs in the root canal process, the better the prognosis is. Why?

Answer 41

later --> more instrumentation and disinfection occurred prior to the fracture = greater proportion of bacteria removed and killed