JVD 2020 #1 Endodontic Disinfection for Orthograde Root Canal Treatment in Veterinary Dentistry; Sasser Flashcards Preview

JVD 2019-2021 > JVD 2020 #1 Endodontic Disinfection for Orthograde Root Canal Treatment in Veterinary Dentistry; Sasser > Flashcards

Flashcards in JVD 2020 #1 Endodontic Disinfection for Orthograde Root Canal Treatment in Veterinary Dentistry; Sasser Deck (18)
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1
Q

Define biofilm

A

Sessile multicellular microbial community that is attached to a surface and enmeshed in a self-produced matrix of extracellular polymeric substance

2
Q

How much more resistant are bacteria within biofilms to antimicrobials?

A

100 to 1000-fold more resistant to antimicrobial agents

3
Q

Define smear layer

A

ultrafine layer of inorganic and organic substances, dentin particles, remnants of vital or necrotic pulp tissue, microorganisms and retained irrigants formed by shaping and irrigating the root canal

4
Q

What are the possible problems/sequela of the smear layer?

A

harbors microorg., reduces dentin permeability, compromises adequate disinfection by limiting disinfectant diffusion inside the dentinal tubules and is potential channel for microleakage

5
Q

What are the mechanical and chemical objectives of Irrigation in Endodontics?

A

flush out debris
lubricate the canal
dissolve organic & inorganic tissue
prevent formation of smear layer

6
Q

What are the biological objectives of Irrigation in Endodontics?

A

Highly effective against anaerobic and facultative microorg.
Inactivates toxins
Is nontoxic to vital tissue
Disinfects areas inaccessible to endo instruments

7
Q

Properties of an IDEAL irrigant for RCT?

A
  1. Nonirritating to periapical tissues
  2. Remains stable in solution
  3. Prolonged, broad-spec antimicrobial effect
  4. Active in presence of blood, serum and protein derivatives
  5. Low surface tension
  6. Does not stain
  7. Does not induce cell-med immune response
  8. Able to dissolve necrotic pulp and biofilm
  9. Prevents or dissolves smear layer
  10. Able to disinfect dentin/tubules
  11. Non toxic/carcinogenic and doesn’t interfere with healing
  12. No adverse effect on physical properties of exposed dentin
  13. No adverse effects on sealing ability of filling materials
8
Q

Key points of Sodium Hypochlorite (NaOCl)

A
  • Most commonly used irrigation solution b/c of ability to destroy variety of microbes and dissolve necrotic pulp and organic debris of smear layer
  • Conc 0.5-6%
  • in water, produces hypochlorous acid and chlorite ions–> dissolve organic tissues
  • removes exposed collagen fibrils, which decreases adherence for E. faecalis
  • Efficacy can be improved by incr temp of solution, volume, contact time (5-20m) and using agitation/activation methods
    • heating 0.5% NaOCl to 113F dissolved pulp as well as 5.25% root temp; Elevating temp to 140F resulted in complete pulp dissolution (diff study)
  • Loses dissolving/antibact capacity within 2 mins–> replenish!
9
Q

What are the limitations/disadvantages of Sodium Hypochloriate (NaOCl) irrigating solution?

A
  • It will not dissolve/remove the entire smear layer
  • May negatively affect periapical tissues, if admin forcefully
  • Implicated in hypersensitivity reactions due to phago. of neuts in periapical region
  • Because it removes collagen fibrils when used as final irrigant- could interact and decrease bonding strength of resin-based canal sealer??
  • 5.25% solution compared to 0.5% solution decreases the elastic modulus and flexural strength of dentin due to proteolytic action on collagen matrix (pot weaken tooth)
10
Q

Key Points Chlorhexidine (2% chlorhexidine gluconate) irrigant

A
  • Strongly basic molecule with cationic charges capable of binding to negatively charged surfaces of bacteria– damaging cell wall
  • Bactericidal at high conc and bacteriostatic at low conc
  • Shown activity against Gram + & - bacteria and yeasts
  • Sustantive antimicrobial activity by being readily adsorbed into the hydroxyapatite crystals of dentin and released back (tx residual bacteria)
  • Differs from NaOCl as it does not remove collagen fibrils- may improve resin-dentin bond
  • lower grade of toxicity locally & systemically compared to NaOCl– less likely tissue rxn with extrusion
11
Q

Limitations/Disadvantages of Chlorhexidine gluconate 2% irrigant

A
  • Inability to dissolve organic debris compared to NaOCl
  • Cannot destroy resistant biofilm structure
  • Creates parachloroaniline insoluble precipitate when used with NaOCl
    • Parachloroaniline can cause cyanosis, carcinogenic, penetrates tubules and interferes with sealer
12
Q

Key points Ethylenediaminetetraacetic acid (EDTA) irrigant

A
  • Demineralizing- used to remove the inorganic mineralized components of smear layer
  • highly biocompatible
  • normally conc 15-17% disodium EDTA liquid or paste
  • Detergents frequently added to solution to aid in wetting of the root canal wall and increase penetration into the dentin
  • Lubrication of hand or rotary files
  • Most commonly used with or alternately with NaOCl to enhance cleaning/antimicro
  • EDTA retains Ca-binding abilities when combined with NaOCl but NaOCl will lose some tissue-dissolving capacity
13
Q

Limitations/Disadvantages of EDTA irrigant

A
  • Little to no antimicrobial effects
  • When used by itself, incapable of removing entire smear layer and disinfection
  • EDTA as a final irrigant demineralizes dentin, exposing collagen, and potentially creates ideal envir for residual E. faecalis to adhere
14
Q

Key points MTAD - “mixture of tetracycline, acid and detergent” irrigant

A
  • Combination irrigant as alternative to EDTA as final rinse
  • supplied as powder and liquid when mixed creates aqueous sol 3% doxycycline, 4.25% citric acid as a demineralizing agent and 0.5% polysorbate as a detergent
  • Synergistic effects on disruption of bacterial cell walls and membranes, effectiveness against E. faecalis
  • Increasing effectiveness of MTAD in eliminating smear layer by first irrigating canal with 1.3% sol of NaOCl
  • has not demonstrated effects on flexural strength or elastic modulus of dentin- beneficial if using resin-based sealer
  • Failed to demonstrate dentin disinfection against E. faecalis compared to 5.25% NaOCl
15
Q

Delivery of Endo Irrigants

A
  • Critical component of chemical debridement and disinfection
  • Irrigation dynamics depend on ability of irrigant sol to be dispersed to apical portion
    • penetration depth of needle, diameter and length of root canal, diameter of needle, irrigation pressure and velocity, type and angle of needle bevel
  • needle–> flexible and has one side opening to prevent excess pressure/velocity apically
  • Standard 25- or 31-mm endo needles shorter than many veterinary species canal lengths thus disinfection of most apical portion impossible
16
Q

Negative- pressure irrigation

A
  • Irrigant delivered to the coronal access site and aspirated down the canal to the apical terminus of needle then drawn into the microcannula needle through a series of holes in terminal aspect.
  • Microcanula needle has sequence of 12 laser drilled microscopic holes; manufactured in 32 and 50mm lengths making adaptation to the longer canals possible.
  • Less risk of periapical exgtrusion of irrigant
17
Q

Manual canal irrigation

A
  • Frequent replenishment of solutions, flusing debris from the root canal space with placement of irrigant in area of microorganisms
  • Actual exchange of fluids occurs within 1.0 to 1.5mm apical to needle tip
  • Wider needle enables more active flushing but risks wedging in canal limiting necessary backflow of irrigant and potential apical extrusion
18
Q

Key points of Intracanal Medicaments

A
  • Use when standard disinfection and tissue disolution does not resovle pulpal bleeding during standard RCT
  • Use as root canal dressing between 2 endo appointments
  • Impede bacterial regrowth, supply continued disinfection and create a physical barrier in the root canal system
  • Calcium hydroxide most commonly used as slurry with water or NaOCl
    • high pH provides sustained broad-spec antimicrobial, capacity to dissolve necrotic tissue remants, bacteria and by-products
    • Needs complete removal at 2nd appointment to reduce effect on sealer
    • may have limited action on biofilm and E. faecalis

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