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BDS4 Endodontics > 4. Chemomechanical Disinfection > Flashcards

4. Chemomechanical Disinfection Flashcards

1
Q

What is the cause of Endodontics disease?

A

Bacteria, fungi and viruses

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2
Q

How does endodontic disease occur?

A

It occurs as bacteria, viruses and fungi invade the root canal and develop into a biofilm which is a complex community that adhere to dentine surfaces and embed in a complex ECM and the biofilm allows the pathogens to reside within a protective environment where collaboration occurs to help evade attempted by the dentist to eradicate

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3
Q

What are the clinical objectives of endo therapy? 2

A

removal of canal contents

eliminate infection

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4
Q

What makes Endodontics treatment much harder?

A

Isthmuses, apical deltas, lateral canals which make it easier for bacteria and fungi to evade out attempts to eradicate them

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5
Q

Who described the process of chemomechanical disinfection?

A

Herbet shilder

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6
Q

What is chemomechanical disinfection?

A

This is a process whereby we employ mechanical means to debride and shape the canal and chemical means to try to enhance biofilm destruction

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7
Q

What are design of objectives of chemomechanical disinfection?

A
  1. create a CONTINOUSLY TAPERING FUNNEL SHAPE
  2. Maintain APICAL FORAMEN IN ORGINAL POSITION
  3. keep apical opening AS SMALL AS POSSIBLE
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8
Q

What does mechanical disinfection allow for

A

Allows for us to use irrigation solution and place medicaments in the canal to attempt to eradicate residing pathogens in the canal space

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9
Q

How do we carry out mechanical debridement?

A

we follow a systematic approach from coronal aspect and work apically to eradicate pathogens in coronal aspect then more apically to less infected area of canal

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10
Q

What is Bactria load like in canal?

A

Greatest at coronal aspect of canal and least at apical aspect

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11
Q

Why do we carry out mechanical debridement coronally first?

A

We to this to eradicate pathogens and prevent us carrying infected material down the tooth

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12
Q

What are the 7 stages of mechanical disinfection of root canal system?

A
  1. prepare tooth
  2. access cavity
  3. straight line access
  4. initial negotiation of canal
  5. coronal flaring
  6. working length determination
  7. apical preparation
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13
Q

Does size really matter in terms of apical preparation?

A

Size is determined by the initial size of root canal apex and if we use a master file that is too small then we can irrigate canal properly - so WE NEED TO AIM FOR AT LEAST SIZE 25 (SS FILE SIZE 30)

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14
Q

What is the purpose of mechanical shaping?

A

To allow for chemical disinfection - makes space for irrigant

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15
Q

What are the 5 main properties irritants must have?

A

Low cost

ability to kill biofilm microbes

ability to detach biofilm

Non toxic to PA tissue tissue

Non allergenic

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16
Q

What are the ideal rpoeprties of irrigants?

A 
	Low cost 
	Killing biofilm microbes 
	Detachment of biofilm
	Washing action of canal
	Reduction of friction 
	Improving cutting of dentine by instruments 
	Temperature control 
	Dissolution of organic and inorganic matter 
	Good penetration within the RC system 
	Killing of planktonic microbes 
	Non-toxic to PA tissue
	Non allergenic 
	Doesn’t react with negative consequences with other DMs
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17
Q

Why is sodium hypochloride good for irrigation?

A

its if effective at disrupting the biofilm and killing bacteria cells (dislodging biofilm from substrate)

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18
Q

What is the issue with CHX as an irrigant?

A

Very good antimicrobial but not effective at dislodging the biofilm

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19
Q

How does sodium hypochlorite work?

A

In solution it ionises in water into sodium and hypochlorite ion

there is an equilibrium with the hypochlorous acid and HOCl is responsible for antibacterial activity

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20
Q

Why do we use sodium hypochlorite?

A

We use this because it has POTENT ANTIMICROBIAL ACTIVITY, KILLS BACTERIAL CELLS AND DISLODGES THE BIOFILM, DISSOLVES PULP REMENANTS AND COLLAGEN

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21
Q

sodium hypochlorite the only irrigant that can what …

A

dissolve necrotic and vital tissue

22
Q

How does sodium hypochlorite help disrupt the smear layer?

A

By acting on organic component

23
Q

What are the 5 factors important for use of NaOCl

A

volume

concentration

contact

mechanical agitation

exchange

24
Q

What concentrations of NaOCl can be used?

A

Anywhere between 0.5-6% - at lower concentrations its not very active against organic tissue and at 6 its very active against organic tissue - we want to establish a middle group

25
Q

What conc of NaOCl is best to use?

A

Best to find a middle ground where its sufficiently antimicrobial and disrupts biofilm but doesn’t have side effects on dentine - we use 3%

26
Q

What NaOCl do we use in GDH?

A

Parcan - 3% solution of sodium hypochlorite

27
Q

Why is the volume of sodium hypochlorite relevant?

A

Its relevant because it inactivates quickly and needs replenished regularly to function

28
Q

What is link between time and sodium hypochlorite?

A

Longer its in canal for more effective it is at dissolving tissue disrupting biofilm

29
Q

Why must we do coronal flaring and apical shaping?

A

so we can deliver irrigant to apical aspect of canal - we create early coronal flare then apical shape so we can deliver the irrigant and disrupt the biofilm and have anitmicorbial action

30
Q

How do we deliver sodium hypochlorite?

A

With a syringe and needle system - we use a flat cut safe needle that is side vented and safely shaped to prevent outpouring of solution ahead of needle which can cause tissue damage however issue is we may not deliver naocl to where we want

31
Q

How do we overcome the risk that we dont deliver NaOCl apically?

A

We use mechanical agitation to ensure the solution reaches all aspects of the canal

32
Q

How do we carry out mechanical agitation?

A

sonic device such as end-activator or ultrasonic device where we create a fluid flow and exchange of irrigant leading to improved irrigation and penetration

33
Q

What is the endoactivator?

A

Sonic device that has fibre tips that vibrate and agitate the solution in the canal space to remove debris and disrupt the biofilm

34
Q

What is manual dynamic irrigation?

A

This is where we place GP point into root canal and pump it in and out just short of working length

35
Q

What is the problems with NaOCl?

A

It has ability to dissolve organic tissue –> DENTINE (this is why we try to use 3% concentration to protect the dentine)

Unable to remove smear layer by itself

36
Q

Why must we protect dentine?

A

This is because hypochlorite will penetrate the dentine and as we increase the conc the depths of penetration increases which can have a significant effect because canal space is so small

37
Q

What is the smear layer?

A

Layer of organic and inorganic material that is laid down when we machine the root surface

38
Q

How is smear layer created?

A

When we cut dentine

39
Q

What is issue with smear layer?

A

It can limit disinfection in tubule and prevents sealer penetration in tubules

40
Q

How do we aid smear layer removal?

A

17% EDTA or 10% citric acid

41
Q

What is EDTA?

A

A chelating agent that is capable of removing the smear layer when used with sodium hypochlorite

42
Q

What percentage of EDTA is used to disinfect the canal?

A

17%

43
Q

When is EDTA used?

A

As the penultimate rinse - for 1 minute in the canal

44
Q

What must we consider when using EDTA and NaOCl?

A

The potential for interaction between EDTA and NaOCl - if they interact there efficacy can be affected so after using NaOCl we must ideally withdraw, aspirate, dry then place next irrigant (some advocate irritating with sterile water)

45
Q

What can hypochlorite do to clothes?

A

It has effect on organic material so can bleach the clothes - provide pt with bib!!!

46
Q

What are warnings with using hypochlorite?

A

can bleach pts clothes - bib

eye protection essential - can lead to blindness if splashed in eyes

can extrude apically and cause tissue necrosis - need to ensure we keep in canal and dont use too much pressure

allergic rxn

47
Q

What is chlorohexidine digluconate?

A

Antimicrobial agent (less anti fungal activity but strong antibacterial)

can’t disrupt biofilms like NaOCl

48
Q

What is risk of adding CHX into irrigation sequence?

A

Increased risk of interaction

reacts with hypochlorite to form mucky brown precipitate which an stain teeth

can add complexity with little benefit

49
Q

What is the proposed shaping and cleaning protocol?

A
  1. throughout instrumentation and shaping of canal irrigate with 3% NaOCl and then after we have done this we want to irrigate with NaOCl for a further 10 mins (start the clock after shaping is done and do manual irrigation with at least 30ml of sodium hypochlorite)
  2. aspirate NaOCl with syringe, dry canal and then place 17% EDTA for one minute as penultimate rinse - manually irrigate, aspirate, dry
  3. place final 3% NaOCl rinse so we can manage the biofilm within the root canal system and leave a clean canal ready to obturate
50
Q

Why dont we start clock for 10 minute irrigation protocol until we have completely shaped canal?

A

NaOCl won’t penetrate until prep is completed

BDS4 Endodontics (7 decks)

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