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Reasons for REXT
- o Crump POORPAST
- o P – perforation
- o O – obturation
- o O – overfill
- o R – root canal missed
- o P – perio disease
- o A – another tooth
- o S – split
- o T – trauma
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Reasons for NSRCT failure
- oIntra-radicular infections (Nair)
- oExtra-radicular infections (Nair & Sjogren)
- Actinomyces Israelii, Propionibacterium propionicum
- oForeign body reaction (Nair)
- oCysts (Nair)
- 50% granulomas
- 35% abscesses
- 15% cysts
- • 61% true cysts
- 39% pocket cysts will heal with orthograde endo therapy
- oCholesterol crystals (Nair)
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When would you RETX based on coronal microleakage?
o Torabinejad, Kettering 1990 – time needed for bacteria to penetrate 50% of obturated canals was 19 days (S. epidermidis)
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- What would you base your initiation of RETX decision on?
- o Van Nieuwenhuysen – RETX if PARL, clinical signs and/or symptoms; HOWEVER, if no or little radiographic evidence and PARL, if clinical signs and symptoms are absent, if previous root filling was radiographically DEFICIENT, then radiographic monitoring is BEST b/c led to complications in only a limited number of cases
- o Hoen – if asymmetric obturation, then an additional canal was located during RETX 89% of the time
- o Friedman, Stabholz 1986 – Good review of RETX case selection
- o Huumonen, Kvist 2006 – MB root Max 1st molars; 38/39 PARL seen w/ CBCT (better than PAXs); 33/39 w/ PARL; 27/30 had unfilled MB2
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What if a previous treated tooth is thermal sensitive?
- o Keir 1991 – thermal sensitivity after RCT due to missed canals; heat testing can identify IP in late stages of disease, especially NSRCT w/ continued pain
- o Tidwell – Possible causes of thermal sensitivity of root canal treated teeth are:
- Inadequate cleaning, shaping, and obturation
- Presence of extra, undetected canal(s)
- Silver cones OR metallic GP carriers in direct contact w/ coronal restoration or PA tissues
- Broken metallic instruments in contact apically w/ vital tissue
- Defective coronal restorations
- Referred pain from another tooth
- Unknown source
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- Chloroform
- o McDonald 1992 – Chloroform safe for clinical use; not harmful to patient nor office staff; air vapor levels way below OSHA mandated levels
- o Kaminski 1998 – Chloroform no health risk to patient; amount expelled thru apical foramina is several orders of magnitude below the permissible toxic dose
- o Kaplowitz – chloroform only one out of 5 solvents that totally dissolved GP
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- How could you possible remove over-extended GP?
o Metzger – soften GP w/ solvent and remove to a distance 2-3mm short of apex, then the remaining GP which is hopefully preserved as a solid piece can be removed by a Hedstrom the file is extended 0.5-1mm beyond the apex, firmly engage the GP and slowly remove the file w/ the GP (plastic carrier melts @ 300 C)
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- How would you remove a Thermafil carrier? Separated instrument?
- o Wolcott – System B is set to 225 C. Plugger placed buccal and then lingual to depth of 10-15mm for 5-8 sec. While the GP is thermoplasticized, place a 25-35 Hedstrom(s) along the carrier, turn clockwise to engage the carrier and pull out in one piece
- o Suter – place 21-GA needle over separated instrument of silver point, then push Hedstrom file thru the needle in CW direction to interlock and then all 3 parts can be removed coronally
- o Braided-file technique
- o Super-glue
- o Rotate CCW out with U/S
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- How & Do silver points cause a problem? YES
- o Leakage from around the round wire within not such a round canal causes washout of the cement and fluid contact w/ the silver point; oxidation of the wire leads to corrosive by-products
- o Seltzer – silver wires removed from failed endo cases showed corrosion products of silver sulfate products which are cytotoxic
- o Suter – place 21-GA needle over separated instrument of silver point, then push Hedstrom file thru the needle in CW direction to interlock and then all 3 parts can be removed coronally
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- What to use for irrigation, final irrigation or IC med? NaOCl; Final w/ 2% CHX liquid; IC w/ 2% CHX gel
- o Gomes – 2% CHX gel >>> CaOH against E. faecalis
- o Waltimo 1998 – Candida less susceptible to CaOH; Candida found in 7% of initial failures possible cause of persistent infections
- o Ruff 2005 – 6% NaOCl & 2% CHX were equally effective and statistically superior to MTAD and EDTA as antifungals
- o Dunavant 2006 – 6% and 1% NaOCl were more efficient in eliminating E. faecalis biofims than other solutions testing (2% CHX, MTAD)
- o Ruff & Dunavant & Gomes & Basrani & Bui, Baumgartner irrigate w/ NaOCl throughout procedure; if need IC med, then use 2% CHX gel; final rinse w/ 2% CHX liquid; no NaOCl then CHX, use EDTA immediately before or after CHX
- o Zhu 2010 – Prevalence of E faecalis was 40.6% in teeth w/ persistent AP
- o Wang 2007 - 2% CHX is effective root canal disinfectant and additional intra-canal dressing did not significantly improve the bacteria reduction
- o Vianna 2007 – chemo-mechanical preparation w/ 2% CHX reduced endotoxin levels by 44.4%
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- Perforation Repair? Use MTA; no matrix needed for healing
- o Torebinejad – MTA for furcal perfs;l no internal matrix needed; MTA had less leakage than IRM or amalgam in root perfs
- o Holland – no inflammation and cementum deposited over MTA
- o Saunders – MTA leaked less than Vitrebond
- o Jew – prognosis of perforation depends on time elapsed (immediate better), location relative to attachement (more apical the better), size and sealability of repair material; better prognosis is in the apical third or middle third of root; contamination w/ oral fluids leads to failure
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Post removal
- o Johnson 1996 – U/S vibration effective for removing post
- o Berbert – reduced forces were necessary to remove post with U/S
- o Abbott – post removal is predictable w/ good outcome; incidence of root fx is rare
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