Disinfection of the Root Canal Space escn session 5



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Disinfection of the Root Canal Space

ESCN Session 5

Robert S. Roda DDS MS



http://web.mac.com/robertroda



  • Purpose of Root Canal Therapy

    • To prevent and cure apical periodontitis




  • An inflammatory process in the periradicular tissues caused by microorganisms in the infected root canal




  • Initial Infection

    • Mostly gram negative and anaerobic

    • eg. Fusobacterium




  • Post-Treatment Infection

    • Gram positive facultative anaerobes

    • eg. Enterococcus faecalis




  • Microorganisms

    • Two forms:

      • Planktonic

      • Sessile

        • Forms a biofilm




  • Biofilm Composition

    • Bacteria

    • Polysaccharide Extracellular Matrix

      • Protection

      • Signaling

      • Nutrition




  • Biofilm

    • Five Stages of Biofilm Development

      1. Reversible attachment

      2. Irreversible attachment

      3. Matrix secretion

      4. Growth

      5. Differentiation

        • Detachment




  • Biofilm

    • After attachment to a surface, a bacterium expresses a different set of genes

    • Microorganisms in biofilms have reduced susceptibility to antimicrobial agents

    • Biofilms adapt to changing conditions

    • Becomes more persistent under stress

    • Less susceptible to second application of disinfectants

    • Bacteria can transfer acquired resistance to other bacteria




  • Bacteria in Dentinal Tubules




  • Aim of Endodontic Therapy

    • Removal of the biofilm from the canal space and prevention of re-infection

  • Two Stages of Root Canal Therapy

    • Reduce / Eliminate Bacteria

      • Mechanical canal preparation

      • Chemical disinfection




    • Prevent Re-infection

      • Apical seal

        • Sealed obturation

      • Coronal Seal

        • Sealed Restoration




  • Mechanical Preparation

    • Removal of most organic substrate from the canal system

    • Development of a purposeful form

      • to allow deep penetration by irrigants

      • for reception of a dense root filling




  • Mechanical Preparation

    • Broaches

    • Hand files

    • Rotary files

    • Ultrasonically activated files

    • Sonically activated files

    • Lasers




  • Instruments Don’t Get Everything

  • Instruments Create Smear Layer



  • Smear Layer

    • A layer of debris on dentin

      • Organic component

      • Inorganic component

        • Dentin chips

        • Foreign debris (insoluble)

    • Created by mechanical scraping of dentin




  • Affects:

    • Restorative dentistry (bonding)

    • Periodontics (regeneration)

    • Endodontics? (disinfection and seal)




  • Should it be removed?

    • Yes:

      • Potentially infected material / substrate

      • Prevents disinfectants and filling materials from getting into tubules

      • Detriment to apical seal

    • No:




  • Chemical Disinfection

    • Irrigation

      • Passive

      • Active

    • Inter-appointment Medicaments

      • Phenolic

      • Calcium hydroxide




  • Effectiveness is Proximity Dependant




  • Irrigants

    • Distilled water

    • NaOCl

    • EDTA

    • Chlorhexidine




  • Distilled Water

    • No antibacterial action

    • Does not dissolve tissue



  • Sodium Hypochlorite

    • 6% vs 3% NaOCl

    • Kills some bacteria (E. faecalis is resistant)

    • Dissolves necrotic tissue

    • Does not remove smear layer

    • Reduces bonding strength

    • Current Irrigant of Choice




  • EDTA

    • Kills some bacteria?

    • Removes smear layer

    • Erosion of dentin




  • Chlorhexidine

    • 0.12% vs 2%

    • Kills some bacteria (similar to NaOCl)

    • Kills E faecalis

    • Does not dissolve tissue

    • Toxicity?

      • Tissue Fixitive

      • Carcinogenic byproducts?




  • Smear Layer Removal

    • Two stage chemical process

    • Remove inorganic component

      • Mild acids (chelation)

      • EDTA

      • Citric acid

      • Phosphoric acid

      • Tetracycline

    • Remove organic component

      • Sodium hypochlorite




  • Current Disinfection Technique

    • Irrigate thoroughly with NaOCl

    • Evacuate NaOCl

    • Syringe EDTA into canal (1-2 min)

    • Evacuate EDTA

    • Flush with NaOCl (1 min minimum)

    • Evacuate NaOCl

    • Flush with 2% CHX (5 min)

    • Use paper points to dry




  • BioPure™ MTAD™ Cleanser

    • Mixture of Tetracycline and Acid - Detergent

    • Detergent (Tween 80) ™ acts as a surfactant - facilitates penetration

    • Citric acid removes smear layer

    • Doxycycline

      • removes smear layer

      • kills resistant bacteria

    • Removes Smear Layer




  • Properties of MTAD

    • Effective when combined with any concentration of NaOCl over 1.3%

    • Kills E. faecalis better than 2% CHX

    • Kills bacteria in whole saliva better than NaOCl

    • Sustained effect? (binds to dentin)

    • Biocompatibility > EDTA, 0.12% CHX, 5.25% NaOCl

    • Does not affect flexural strength of dentin

    • Does not decrease bond strength of dentin

    • FDA Approved 2004

    • Allergenicity

      • True allergy is rare

      • Do not use in pregnant women or children under age 8




  • MTAD™ Cleanser Technique

    • Irrigate thoroughly with NaOCl

    • Evacuate NaOCl

    • Syringe 1ml BioPure MTAD cleanser into canal (5 min)

    • Flush with 4ml BioPure MTAD cleanser

    • Use paper points to dry




  • QMix 2in1

    • EDTA and Chlorhexidine

    • Removes smear layer

    • Kills planktonic bacteria

    • Kills biofilm bacteria




  • QMix Protocol

    • Irrigate with NaOCl throughout

    • Dry canals

    • QMix for 90 sec

    • Dry Canals

    • Obturate




  • Increase Irrigant Effectiveness

    • Volume

    • Concentration
      Temperature
      Agitation

    • Combination - NaOCl + ProLube® or RC Prep ®

    • Change solution frequently

    • Increase time of contact



  • Irrigation - Two Types

    • Passive

      • Allow the irrigant to passively work

      • Soaking

    • Active

      • Add heat or agitation

        • Increase irrigant action

        • Tissue dissolution

        • Increase antimicrobial action

        • Increase irrigant flow

        • Clean canal iregularities




  • Passive Irrigation

    • Soaking

    • EDTA 1-2 minutes

    • NaOCl 1/2 hour*

    • The longer the better




  • Active Irrigation

    • Manual Dynamic

    • Sonic

    • Ultrasonic

    • EndoActivator

    • EndoVac

    • Ultrasonic Irrigation




  • Manual Dynamic Irrigation

    • Manual push-pull motion

    • Use a fitted master gutta percha cone

    • Forces irrigants into canal ramifications




  • Sonic Instruments (2-3 kHz)

    • Sonic Handpieces (Micromega 1500/3000)

    • sonic vibrations created by air/water jet

    • vibrates in a figure eight motion

    • difficult to control tip movement

    • canal walls left rough (creates smear layer)

    • slow

    • relatively less expensive than ultrasonic

    • best use is for coronal instrumentation and for irrigation




  • Ultrasonic Instruments (25-30 kHz)

    • piezo-electric energy applied to files

    • acoustic streaming (cavitation?)

    • used for canal flaring (middle, coronal 1/3)

    • creates (removes) smear layer?

    • removal of debris from inaccessible fins

    • can use hypochlorite for irrigant (tube damage)

    • potential for instrument fracture



  • Ultrasonic Instruments (25-30 kHz)

    • Ultra-sonic operates in a linear motion.

    • Controlled tip motion.

    • More energy through a predictable range of motion.

    • Low Power Setting – 1 to 5

    • Must use a light paint brush stroke

    • Cleaning Webs and Fins

    • C-Shaped Canals




  • EndoActivator

    • Soft plastic tips

    • Does not create smear layer

    • Battery operated (cordless)

    • Sub-sonic oscillation (10000 rpm max)







  • Ultrasonic Irrigation

    • Irrigation needle attached to ultrasonic

    • Hypochlorite overextension?




  • Minimally Invasive Endodontics

    • Conserve peri-cervical dentin

    • Attempt to reduce incidence of fracture

    • Minimize size of access

    • Minimize size of root canal preparation




  • OneStudy

    • Compared TEC and CEC

    • WaveOne instrumentation

    • Static Fx load Instron)

    • Canal cleanliness - micro CT

    • TEC – less load to Fx in premolars and molars (incisors unaffected)

    • CEC – compromised canal cleaning only in lower molar distal roots


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