CSA endodontic instrumentation

Question 1

Why anaesthetic may not be profound during endo ?

Answer 1

o Hyperexcitability of nerve fibres – C nerve fibres
o Increased blood flow due to infection – removes anaesthetic faster
o Acidic pH of inflammatory products make anaesthetic less effective
o Patient factors like response to anaesthesia/differing pain threshold/anxiety levels

Question 2

What If inadequate anaesthesia occurs

Answer 2

Intraligamentary/intrapulpal/intraosseous procedures occur

Question 3

What are function of RubberD during endo

Answer 3

o Protection of airway 
o Protection from irritants 
o Prevention of contamination 
o Improves access & visualisation 
o Improves patient comfort

Question 4

Endodontic RD involves ?

Answer 4

o Oroseal putty> forms seal around the tooth & RD
o Dental floss >secure clamp & prevent swallowing – eases dam through CP
o Wedgit>secures rubber dam
o Gauze & aspiration> improves patient comfort

Question 5

What to check before accessing pulp chamber?

Answer 5

o All caries & defective restorations removed
o Crown deemed to be restorable
o sound coronal restoration can be placed

Question 6

What does pre op radiograph show?

Answer 6

project tooth as near to its natural site as possible, show full roots & 2-3mm of periapical tissue,

Question 7

What can we determine from radiograph?

Answer 7

o No./morphology of roots/canals
o Extent of current restoration
o Presence caries
o Presence of canal sclerosis/pulp stones/previous RCT/ Fractured instruments

Question 8

What are the aims of coronal access?

Answer 8

• Remove roof of pulp chamber
• No damage to pulpal floor
• Straight line access
• Conservative
• Retentive to accommodate for temporary restoration
• knowledge of tooth & pulp anatomy essential

Question 9

Whats needed to find canals?

Answer 9

require good light, magnification (loupes or microscope) & explorer

Question 10

How to access pulp after coronal aspect prepped?

Answer 10

• Most of tooth removal carried out with high speed
• Slow speed burs = remove roof of pulp chamber if present & dentine from around canal openings
• Ultrasonic instru. may used to remove dentine around canal orifices

Question 11

What burs are used when accessing pulp?

Answer 11

“safe ended” = no cutting flutes or diamonds at tip – used safely around floor of pulp chamber to remove dentine laterally w/o risk of perforation via floor

Question 12

What does prep involve?

Answer 12

involves mechanical & cleaning & shaping w/ chemicals to disinfect canal
= Chemo mechanical

Question 13

What does success of RCT depend on ?

Answer 13

cleaning/shaping – removes much debris as pos. whilst not compromising strength of the tooth

Question 14

What is mechanical prep?

Answer 14

use of hand files

•Gates gladdens burs be used in straight coronal portion of canal

Question 15

What is the straight coronal prep ?

Answer 15

occur 1st to create funnel shape
oBacteria/Necrotic tissue removed
o Files & Gates Glidden burs usedl
o Files then to prep coronal 2/3 of canal

Question 16

What are gate gidden burs?

Answer 16

• 6 sizes – by number of grooves in the shank (0.5 – 1.5 mm)
• don’t cut at tip> won’t cut outside of canal
• stainless steel & designed to break easily at shank when stress applied

Question 17

What is used to prep apical 1/3

Answer 17

• Stainless steel K Flex Files

* rubber stopper on each file used to indicate length of canal to reproducible landmark

Question 18

What is chemical preparation ?

Answer 18

(EDTA) used with files to lubricate canal & remove smear layer
• Sodium Hypochlorite irrigation throughout

Question 19

Why is SODIUM hypochlorite ideal?

Answer 19

• destroys microorg
• dissolves organic matter
• wets canals
• removes debris by flushing
• biocompatible

Question 20

What are intra canal meds?

Answer 20

placed in canals between visits, when:
o persistent infection even w/ chemo mechanical cleaning
o Apex incomplete – stimulates apexification for immature teeth
o Insufficient time for obturation/preparation

Question 21

What are requirements for intra canal med?

Answer 21

o Antibacterial
o Aids periapical healing 
o Therapeutic 
o Anti-inflammatory 
o Long lasting 
o Non – irritant 
- Easy to use & remove 
o Cheap

Question 22

What is most common intra canal med?

Answer 22

calcium hydroxide

Question 23

What is aim of temporisation

Answer 23

o Seals tooth/ prevent contamination
o Restores function of tooth
o Prevents over eruption/drifting
o Restores aesthetics

Question 24

What is used for interim temp. restoration ?

Answer 24

Kalzinol (zinc oxide eugenol),
glass ionomer, polycarboxylate cement, intermediate restorative material and
composite

Question 25

What is obturation ?

Answer 25

• Once canals been cleaned/shaped
• provides 3D seal of canal system
• Gutta percha most commonly used
• Matched finger spreaders used to condense GP into canal & softened by heat/solvents

Question 26

Why do we fill canal/obturate?

Answer 26

prevents microorganisms entering & reinfecting canal

- not possible to sterilise root canals completely – any residual micro. be trapped & w/o nutrients

Question 27

What are used along Endo sealers ?

Answer 27

o Cement root filling material to canal
o Fill in voids
o Act as antibacterial
o Be radiopaque

Question 28

What are common endo sealers

Answer 28

Zinc oxide eugenol, calcium hydroxide & glass ionomer