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BDS3 - Endodontics > chemomechanical disinfection > Flashcards

chemomechanical disinfection Flashcards

1
Q

what is a biofilm

A
  • bacteria and fungi develop into biofilm

- complex communities adhering to dentinal surfaces embedded in a matrix

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2
Q

what is biofilm resistance

A
  • antimicrobial may fail to penetrate beyond the surface layers of the biofilm
  • antimicrobials Amy be trapped and destroyed by enzymes
  • antimicrobials may not be active against non-growing microorganisms
  • expression of biofilm-specific resistance genes
  • stress response to hostile environmental conditions
  • protective environment where elaboration to evade attempts to eradicate them
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3
Q

what are the clinical objectives of endodontic therapy

A
  • removing canal contents

- eliminating infection

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4
Q

how can root canal make end hard

A
  • very complex

- all complexities enhance the ability of the bacteria and the fungi to evade our attempts to eradicate them

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5
Q

what is chemomechanical disinfection

A
  • employ mechanical means to deride and shape canal and supplement this with chemical means in order to enhance biofilm destruction
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6
Q

what are the design objectives of endo treatment

A
  • create a continuously tapering funnel shape
  • maintain apical foramen in original position
  • keep apical opening as small as possible
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7
Q

what does mechanical preparation do

A
  • creates space to allow irrigating solutions and medicaments to move effectively eliminate micro-organisms from the root canal system
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8
Q

what are the stages in mechanical preparation

A
  • preparation of tooth
  • access cavity preparation
  • creating a straight-line access
  • initial negotiation
  • coronal flaring
  • working length determination
  • apical preparation
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9
Q

why do we start coronally

A
  • eradicate the most significant infected parts of root canal surface coronally first then move apically where there is less infected material
  • as instrument goes deeper it is less likely to carry with it infective material down
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10
Q

apical preparation size?

A
  • determined by initial size of root canal apex
  • passive exploration known as gauging
  • apical preparation controversial
  • usually at leat ISO size 25 to allow adequate irrigation
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11
Q

what are the ideal properties of an irrigant

A
  • low cost
  • washing action
  • reduction of friction
  • improving cutting of dentine by the instruments
  • temperature control
  • dissolution of organic and inorganic matter
  • good penetration within the root canal system
  • killing of planktonic microbes
  • killing of biofilm microbes
  • detachment of biofilm
  • non-toxic to periodical tissues
  • non-allergenic
  • does not react with negative consequences with other dental materials
  • does not weaken dentine
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12
Q

what is used as an irrigant

A
  • sodium hypochlorite = one of most successful

- Chlorhexidine used but does not give a complete kill of bugs

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13
Q

how does NaOCl work

A
  • ionises in water into Na+ and the hypochlorite ion OCl-
  • establishes equilibrium with hypochlorite acid
  • at acid/neutral HOCl predominates
  • at pH 9 or above HOCl- predominates
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14
Q

why do we use NaOCl

A
  • potent antimicrobial activity
  • dissolved pulp remnant and collagen
  • only root canal irrigant that dissolves necrotic and vital tissue
  • helps disrupt smear layer by acting on organic component
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15
Q

what factors are important for NaOCl function

A
  • concentration
  • volume
  • contact
  • mechanical agitation
  • exchange
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16
Q

what concentration of NaOCl is used

A
  • used between 0.5-6%
  • 0.5% not very active against organic tissue but 6% very active
  • need to find a sweet spot between them
  • many use 5%
  • need good anti microbial activity and organic activity
17
Q

what volume of NaOCl should be used

A
  • sufficient volume
  • becomes inactive very quickly
  • need to replenish it
18
Q

how long should NaOCl be in canal

A
  • long enough to have an effect

- longer it is in canal the more likely to remove tissue

19
Q

what things can help get irrigant to where we want it

A
  • radio-opaque contrast media
  • real-time imagine of bioluminescent bacteria
  • thermal image analysis
  • computational fluid dynamic
  • stained dentine and NaOCl
  • digital subtraction
  • 3D mapping with microCT
20
Q

what needles are best for irrigation

A
  • use a syringe in needle system
  • use safe needles so side vented or shaped to prevent outpouring ahead of needle
  • but then don’t get irrigant at the apex as well
21
Q

what is the problem with straight cut or oblique cut needles

A
  • get force of irrigant ahead of needle which could cause it to go through apex and damage the soft tissue
  • but it does get to the apex
22
Q

what is mechanical agitation

A
  • either use a sonic device or an ultrasonic device where we create fluid flow and exchange of irrigant
  • use it because syringe irrigation alone is not effective enough
23
Q

what is used for mechanic agitation

A
  • endoactivator

- manual dynamic irrigation

24
Q

what is an endoactivator

A
  • used for mechanical agitation
  • sonic device
  • fibre tips that vibrate
  • agitates solution and gets debris removal and biofilm destruction
25
Q

what is manual dynamic irrigation

A
  • used for mechanical agitation
  • use in DH
  • place GP point in Canale and pump irrigant in and out
26
Q

what are some problems with NaOCl

A
  • possible effect on dentine properties
  • inability o remove smear layer itself
  • effect on organic material
27
Q

how does NaOCl affect dentine

A
  • will dissolve organic tissue so will modify or dissolve organic content in dentine
  • penetration of NaOCl into dentine
  • root structure is thin so in some parts, a significant portion of dentine could be structurally altered
28
Q

what is a smear layer

A
  • formed during preparation
  • organic pulpal material and inorganic dentinal debris
  • superficial 1-5µm with packing into tubules
  • smear layer limits disinfection of tubules
  • prevents sealer penetration
29
Q

what can be used along with NaOCl to remove smear layer

A
  • 17% EDTA
  • 10% citric acid
  • MTAD
  • sonic and ultrasonic irrigation
30
Q

how long must EDTA be applied for

A
  • 1 minutes
31
Q

why can’t EDTA and NaOCl both be present in root canal at same time

A
  • dentine is made more susceptible to NaOCl is used with EDTA
  • it is a chelating agent so captures organic content and exposes collagen which can then be acted on by NaOCl
32
Q

how do you use NaOCl and EDTA

A
  • withdraw or aspirate one irrigant dry then use the other and withdraw, aspirate and dry
  • some say use sterile water between irrigants
33
Q

what are some NaOCl complications

A
  • discolouration of fabrics
  • ophthalmic injuries = need eye protection
  • apical extrusion leading to tissue necrosis = need to keep in in canal and not use too much pressure
  • allergic reactions
34
Q

how does Chlorhexidine work

A
  • the positively charged Chlorhexidine molecule is attracted to the negatively charged phospholipid in the cell wall
  • Chlorhexidine binds to the cell wall causing it to rupture
  • the rupturing of the cell wall causes fluid to lead leading to lysis and cell death
35
Q

is Chlorhexidine good as an irrigant

A
  • somewhat active against biofilm but unable to disrupt them
  • well proven track record as antimicrobial
  • poor choice as irrigant
  • biocompatibility considered acceptable
  • risk of anaphylactic reaction
36
Q

how does Chlorhexidine react with NaOCl

A
  • forms para-chlroaniline
  • brown substance
  • cytotoxic and carcinogenic
37
Q

what is the proposed cleaning and shaping or canal

A
  • once canal preparation is complete, the canal should be finally irrigated with
    = 3% NaOCl throughout instrumentation and at leat 30ml after complete with MDI at least 10 minutes prior to obturation
    = 17% EDTA for 1-minute penultimate rinse
    = NaOCl final rinse to ensure adequate activity
  • dry canal using absorbent paper points between irrigants
  • won’t penetrate until complete penetration

BDS3 - Endodontics (10 decks)

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