NSRCT Overview

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NSRCT Overview
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2014-05-04 16:00:26
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ABE Prep
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  1. NS RCT Overview
  2. Apex Locators
  3. Who was instrumental in developing the apex locator / Root ZX?
    • Suzuki – electrical resistance between periodontium & oral mucous membrane was 6500 ohms in dogs
    • Sunada – found same results in human (basis for resistance type EALs)
    • Kobayashi – developed the Root ZX base on a ratio of impedance at 8 and .4 kHz frequencies
  4. How accurate is the Root ZX?
    • Shabahang – 96.2% +/- .5mm of the apical foramen
    • Ounsi – 84% accurate – use apical foramen (major diameter) as measurement
  5. What did Kuttler say about minor constricture?
    anatomy studies, minor diameter is 0-0.5mm from radiographic apex; cemento-dentinal jxn
  6. What is the best known standard of where our filling material should stop?
    Schaeffer 2005 – Meta-analysis; Filling 0–1.0mm short of apex was superior to >1mm or long; 2 yr F/U
  7. What did Cianconi in 2010 find out between EAL and PAX?
    EALs more accurate in determining WL than digital PAXs
  8. Does the pulp status affect EAL readings?
    Dunlap – NSD between vital and necrotic pulps
  9. Does the irrigant solution affect the reading?
    Schindler 2001 – No; NSD in function with 7 irrigants tested
  10. Does apical resorption or an open apex affect the reading?
    • Goldberg – accurate with resorption
    • Katz – preferable method to determine WL in primary dentition
  11. Are EALs safe for use in pts with pacemakers?
    • Garofalo & Dorn – In vitro Root ZX safe – Bingo caused interference
    • Baumgartner – In vivo study found EALs and EPTs safe in 27 pts
  12. Canal Preparation
  13. Why is the ideal working length .5 – 1mm short of the apex
    • Burch and Hulen – avg. .59mm from occlusal aspect of maj diameter to apex
    • Kuttler - .525mm (18-25yr olds) - .659mm (.55yr olds) from major to minor diameter
  14. Discuss historical preparation techniques?
    • Clem, Mullaney – Step back
    • Torabinejad – Passive Step back
    • Marshall – Crown Down Pressureless
    • Abou Ross – Anticurvature Filing
    • Roane – Balanced Force
  15. Do you preflare the canal and why?
    • Stabholz – better tactile sense of the apical constriction
    • Ibarrola – preflaring allowed more consistent EAL readings (allowed access to apical foramen)
    • Roland - .04 taper NiTi files were far less likely to separate in preflared canals

    Baumgartner; Torabinejad; Walton – preflaring is SAFER and NO significant loss of length when determining WL
  16. Can patency filing cause problems?
    Goldberg – cause apical transportation (61% #25, 25% #10) – use small files
  17. Why do you create a guide path?
    Peters – No Protaper instrument fractured is guide path was created
  18. What are the advantages of the balanced force technique?
    • Wu & Wesselink – produced cleaner apical portion of canals vs other hand techn.
    • McKendry – extruded less debris
    • Sepic – less apical canal alteration in curved canals vs step back techn.
  19. Why would you choose to use NiTi rotary files over SS hand files?
    Baumgartner – NiTi rotaries were faster and stayed more centered
  20. What are the properties of NiTi files?
    Haikel – 55% Nickel / 45% Titanium; 2 phases: Austentite & Martensite – cycling between the two phases allows for superelasticity and shape memory; radius of curvature is most important factor for cyclic fatigue, causing failure
  21. Do NiTi files remove more bacteria?
    • Trope – Not any more effected than SS hand files
    • Peters – all type of NiTi rotaries left 35% or more of canal surface area unchanged
  22. At what speed should NiTi rotaries be run at?
    • Gabel & Hoen – Profiles at 333 rpm separated 4x more often as files at 167 rpm
    • Gambarini – recommended electric low torque or right torque motors
  23. How many times can NiTi files be used
    Yared – Up to 10 canals (2-3 cases)
  24. Does sterilization affect NiTi files
    Hicks – 10 cycles through heat sterilization did not increase chance of fracture
  25. Irrigation
  26. What are the benefits of using CHX?
    Jeansonne; White – CHX = NaOCl but won’t dissolve tissue; 72 hr substantivity
  27. What happens when you mix CHX and NaOCl together?
    Basrani- CHX & NaOCl mixed together form a precipitate and color change produces parachloroanaline
  28. How large should the apical preparation be for irrigation?
    Brilliant – size 30
  29. Where should the irrigation needle be placed?
    Sedgley 2005 –irrigate at least 1mm from WL for best antimicrobial effect (1mm better than 5mm); 30-GA
  30. What makes sodium hypochlorite antibacterial?
    Hurst – pH 11; hypochlorus acid is the active antibacterial property of sodium hypochlorite; disrupts oxidative phosphorylation and other membrane activites
  31. Why use full strength sodium hypochlorite?
    • Hand, Smith & Harrison – dilution of 5.25% significantly decreases the ability to dissolve necrotic tissue
    • Siqueira – Increased concentration (4%) most effective against gram – anaerobes and facultative anaerobes
    • Baumgartner – 5.25% is safe for clinical use and does not increase postop pain
  32. When should chlorhexidine be considered as an irrigant?
    • Jeansonne – 2% chlorhexidine & 5.25% NaOCl showed NSD in antibacterial activity; CHX does not dissolve tissue; Consider with NaOCl allergies, perfs and open apicies
    • Haapasalo – CHX activity is reduced by dentine
  33. What about MTAD?
    Torabinejad – Doxycycline, citric acid & Tween-80; use with NaOCl and recommended for smear layer removal – did not cause dentinal erosion seen with EDTA; kills E. faecalis more effectively than NaOCl
  34. Who discussed smear layer removal?
    • McComb & Smith – 1st to describe; used NaOCl & REDTA
    • Sen – made up of organic & inorganic debris (pulp, bacteria and byproducts)
    • Baumgartner – 2 layers: 1-2 microns thin layer on canal wall; up to 40 microns in tubules
  35. Should the smear layer be removed?
    • Torabinejad – Yes - in infected cases it allows more thorough disinfection of canal & tubules; allows better adaptation of obturation material
    • Jeansonne – less coronal leakage with smear layer removal (AH 26)
    • Walton & DrakeNo – blocks bacterial entry into tubules
  36. How do you remove the smear layer?
    • Calt - > 1min EDTA caused excessive peritubular and intertubular erosin
    • Crumpton & McClanahan – 1mL 17 % EDTA for 1 min, followed by 3mL NaOCl
  37. What is EDTA & how does it work?
    • Ethylendiamine tetraacetic acid – Chelating agent – collects Ca ions in dentin making it softer
    • Schilder – self limiting after 7hrs
  38. Ultrasonics
  39. How do ultrasonics work?
    Ahmad, Pitt Ford & Crum – acoustic streaming & not cavitation
  40. Do ultrasonic remove more bacteria?
    Sjogren & Sundqvist – ultrasonics were better than hand instrumentation
  41. Activating NaOCl, does it help?
    • Carver 2007 – addition of U/S irrigation gave 7-fold increase in negative culture
    •  
    • Reader-U/S irrigation better @ debridement and reducing bacteria than needle
    • irrigation alone
    •   
    • Archer–U/S irrigation improves canal & isthmus cleanliness @ 1,2,3 mm versus needle
    •    
    • Sabins 2003 – 30-sec of U/S irrigation is enough; U/S >>>Sonic >>> w/o

    • Ahmad 1987 – described acoustic streaming
    •    
    • Hutter,Reader – U/S irrigation is very effective
  42. Are ultrasonics effective in cleaning canals?
    Jensen & Hutter – 3min passive sonic or ultrasonic following hand instrumentation produced cleaner canals
  43. Intracanal Medicaments
  44. How long do you keep Ca(OH)2 in the canal?
    Sjogren & Sundqvist – 7 day dressing eliminated bacteria that survived instrumentation Nerwich, Figdor & Messer – 2-3wks before increase in outer root dentin pH (9.3) Andreasen – use < 1mo
  45. Discuss Calcium hydroxide and how it works?
    • Hermann – introduced
    • Siqueira – • Hydroxyl ions create free radicals destroying components of bacteria cell membranes.
    • • Free radicals (hydroxyl ions) react with bacterial DNA inhibiting DNA replication and cell activity.
    • • Increased pH (12.5) alters enzyme activity disrupting cellular metabolism and structural proteins.
    • • Ca(OH)2 effective when in direct contact with bacteria which may not always be possible such as bacteria located in dentinal tubules or in the center of bacterial colonies. pH in tubules is increased, but only up to 8-11 (Tronstad).
    • • Certain bacteria such as enterococci tolerate high pH levels of 9-11.
    • • Vehicle used to deliver Ca(OH)2 must not alter the pH significantly.
    • Safavi & Nichols – inactivates LPS in vitro
  46. How do you place Ca(OH)2 in the canal?
    Sigurdsson & Madison – lentulo>injection>K-file
  47. How do you remove Ca(OH)2 from the canal?
    Kenee – use rotary or ultrasonics over irrigation alone (none completely removed)
  48. Why choose CHX over CaOH?
    • Baumgartner–2% CHX kills E faecalis
    •         
    • Gomes–2% CHX gel >>> CaOH against E. faecalis

    • Kim 2002 – CaOH increases apical seal leakage
    •         
    • Ruff 2005 – 6% NaOCl & 2% CHX were equally effective and statistically superior to MTAD and EDTA as antifungals

    • White;Weber – antimicrobial effect of 2% CHX lasted 72 hrs à substantivity-it binds to
    • dentin and is released over time (0.12% CHX lasted 6-24 hrs)

    • Baumgartner; Morgan – CaOH does not dissolve tissue (BUT is does cause it to
    • swell (Turkun)
  49. Obturation
  50. Discuss the hollow tube theory?
    • Richert & Dixon – introduced; canal must filled to the end to prevent outward diffusion of circulatory elements which cause inflammation
    • Torneck – sterile empty polyethylene tubes healed in rat ct – disputes HTT
    • Goldman – no evidence of inflammation at the open ends of Teflon rods implanted in guinea pigs – disputes HTT
    • Wenger – Polyethylene tubes sealed 1mm short with GP/Grossman’s cement elicited little or no inflammation in rat bone – disputes HTT
  51. What is gutta percha made of and what are its properties?
    • Friedman – 65% Zinc oxide; 20% GP; 10 metal sulfates (radiopacity); 5% waxes and resins
    • Schilder – GP exists in beta-semicrystalline state; undergoes change to alpha phase upon heating (42-29 C); compactable not compressable
  52. Is latex allergy a concern for gutta percha? Is it biocompatible?
    Costa & Johnson – no cross reactivity but slight concern with gutta balata additive

    Nair – large pieces were encapsulated and free of inflammation; fine particles evoked inflammatory reponse (macrophages and multi-nucleated giant cells)
  53. How do you place sealer?
    Wilcox – NSD found between file, lentulo, ultrasonics or coated MC
  54. Sealer extrusion, does it affect healing? I use AH+, different from AH-26
    • Leyhausen –genotoxicity and cytotoxicity of resin-based sealers       
    • AH+ --> no genotoxicity or mutagenicity; slight to no cellular injuries

    AH-26 is cytotixic due to formaldehyde release (reason why we don’t use Sargenti’s paste / N2); no formaldehyde in AH+

    Sari & Duruturk – Extruded AH+ does not prevent periapical healing but can delay it
  55. How do you sterilize gutta percha points?
    Senia, Frank – 1 min immersion in 5.25% sodium hypochlorite
  56. Does extrude material cause problems?
    • Augsburger & Peters – did not prevent healing; removed over 6 yr period
    • Baumgartner - extruded GP or sealer was associated with postop pain
  57. What type of spreader should be used for lateral compaction? How far should it penetrate?
    • Joyce – NiTi induce less stress and decrease risk of VRF
    • Walton – less leakage with deep spreader penetration (within 1-2mm)
  58. Discuss the custom cone technique?
    Knapp and Marshall 1972 –3 sec dip gave best adaptation
  59. Compare lateral compaction and warm vertical technique?
    • Baumgartner – NSD in bacterial leakage (continuous wave vs cold lat)
    • Reader – NSD in fill quality; more lateral canals obturated with warm techniques
  60. Can warm techniques damage the periodontium?
    • Eriksson & Albrektsson - > 10 deg C is threshold level for bony necrosis
    • Sweatman & Baumgartner – System B, obtura and ultrasonic delivery of GP < 10 deg change at external root surface
  61. Does the Thermafil system work well?
    Walton – Thermafil leaked most possibly due to stripping of GP off carrier
  62. Is Resilon a better obturation material?
    • Trope – teeth were more resistant to fx
    • Pashley – NSD in leakage compared to GP/AH plus
  63. Is there a problem with Sargenti Paste?
    Newton – demonstrated 6m & 1 yr cytotoxicity
  64. Procedural Errors Overview
  65. How are perforations classified?
    Trope & Fuss – Old or Fresh (better prognosis; Large or small (
  66. How can they be detected?
    • Fuss – apex locators
    • Also: radiographs, blood on paper points, microscope, perio probings
  67. What criteria are important for successful management?
    • Time, size & location
    • Beavers – monkey study showed best repair when immediate; acute inflammation, then formation of new PDL
    • Benenati – delay ok if aseptic
  68. How would you manage a perforation?
    • If larger, consider an internal matrix as proposed by Lemon:
    • Rosenberg – Collacote
    • Alhadainey – Calcium sulfate (Capset)
    • Frank – Ca(OH)2
    • Also: hydroxyapatite, DFDBA, Gelfoam, Calcium phosphate
    • Repair with MTA as proposed by Torabinejad (no matrix required) – 16/16 success X1 yr; Biocompatible and caused cementum formation; less leakage than amal & IRM
    • Baumgartner – less bacterial leakage than amal
    • Daoudi – less dye leakage than Vitrebond
  69. What’s the prognosis of perforation repairs?
    Kvinnsland – 92% using ortho grade and surgical repair
  70. What’s the incidence of separated instruments & does it affect prognosis?
    • Messer – 3% prevalence of retained fractured instruments; NSD in healing - 92% with fx inst & 95% without; lower success (87% & 93%) with preop PARL
    • Crump & Natkin– NSD in failure rate
  71. How would you manage a separated instrument?
    • Attempt removal, bypass or obturate to fx
    • Ruddle – staging platform with modified gates; ultrasonic with DOM; IRS
    • Other methods: Endo extractor tubs with cyanoacrylate; braiding headstroms; wire loop and tube
  72. How do you manage a sodium hypochlorite accident?
    • Gluskin – long acting anesthetics, irrigation with saline to dilute, Amoxicillin, analgesics, steroids, cold compresses & recalls
    • Kleier – diplomate survey – did not affect prognosis; more women than men, necrotic with PARL more common
  73. Restoration of Tooth
  74. What type of temporary restorations do you use?
    • Cavit, IRM & Glass ionomer:
    • Weber – use 3.5mm thickness of Cavit
    • Beach & Hutter – 3 wk bacterial leakage test: no leakage w/ CavitPashley – Cavit, Term & GI provided leakproof seals for 8wks
  75. DO you use orifice sealer?
    Saunder, Wolcott, Wolanek – use orifice sealers to prevent leakage

    Saunders 1997 – Vitrebond barrier no bacterial leakage; w/o barrier 60% leaked by 60 days
  76. Do you leave a tooth open?
    Weine – when access left open, more appointments needed to complete tx and more flare-ups
  77. What is better, one appt endo or two?
    Peters & Wesselink 2002 – 5 yr F/U; 81% vs 71% (single visit better)
  78. Will a AP and postive culture affect how many appointments you see a patient?
    Kvist 2004 – RCCT Microbial eval of 1 vs 2-visit endo w/ AP à both 1 and 2 visit showed bacteria; NSD bwtn groups; MICROBIOLOGICALLY there is NSD bwtn 1 and 2-visit endo w/ AP

    Peters 1995 – bacteria left in dentinal tubules following cleaning, shaping & obturation do not appear to jeopardize the success of treatment; NSD
  79. Leaving a post space immediate or later?, how much GP and is space between post and GP OK?
    Moshonov – No gab bwtn GP and post showed best healing

    Mattison – 5-6mm of GP remains when making post space; use rotary instrument to remove GP

    • Lemon;Abramovitz 2000 – NSD between immediate vs delayed post
    • preparation
  80. How important is coronal seal?
    Salehrabi 2004 – 8yr assessment of initial NSRCT in 1.4 million teeth à 97% retention over 8 yrs; 85% of the teeth which had to be extracted had NO full coverage restoration
  81. Does healing occur with leakage, as we know everything leaks?
    Ricucci 2000, 2003 – Healing of clinical cases CAN occur in the presence of coronal microleakage
  82. When clsoing a case to return them, do you adjust occlusion?
    • Rosenberg – occlusal reduction should prevent post-op pain in teeth initially vital,
    • percussion sensitive, pre-op pain, and/or in the absence of PARL

    • Walton – prophylactic occlusal reduction did not decrease post-op pain; relieve only as
    • needed

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