Endo Retx Flashcards
Reasons for Endo failure
- P erforation
- O bturation incomplete
- O verfill
- R oot canal missed
- P eriodontal reasons
- A nother tooth
- S plit tooth
- T rauma
T umor
A natomical variation
M icroleakage
Endo intraradicular infection def
– Microorganisms remaining in canal space, dentinal
tubules
Extraradicular infection def
– Bacterial plaque on external root surface (biofilm)
– Microorganisms in periradicular lesion (Actinomyces)
Leakage
– Inadequate coronal restoration
– Inadequate obturation
Resistant micro organisms associated with Endo Retx
– E. faecalis, Candida, viruses (?)
Causes of intra radicular infection
• Poor quality endo – Inadequate debridement – Inadequate irrigation – Improper WL • Missed canal • Instrumentation misadventure • Complex anatomy
Reasons for extraradicular infection
• Bacterial plaque (biofilm) on root-end • Bacteria in periradicular lesion (actinomyces) • Microorganisms associated with periodontium
Reasons for leakage
• Inadequate coronal restoration • Quality of coronal restoration may be “more important” than RCT • Inadequate obturation • Fractures – Incomplete crown fracture – Crown - root fracture – Vertical root fracture • Perforations
E Faecalis
– Binds to dentin – Invades dentinal tubules – Endures lengthy starvation – May survive calcium hydroxide
Criteria for end success
- Absence of pain or swelling
- Disappearance of fistula
- No loss of function
- No evidence of tissue destruction
- Radiographic evidence of eliminated or
arrested area of rarefaction after 6 to 24
months
Reasons for Retx of Asymptomatic teeth
• Further enlargement of apical lesion or no
evidence of any reduction in size
• Restorative tx planned on critical tooth
with questionable obturation
• Post space or retentive needs
• Exposure of gutta percha to the oral environment
Exposure of GP to oral environmenr
Studies vary from 1 wk to 90 days
• Gutta-percha does not form complete barrier
• Leaky and lost restorations, caries
– Bacteria can penetrate to apex in < 1 month
– Inadequate coronal seal may account for many
“endodontic” failures
• Retreat if ~ 1 month or greater exposure of
gutta-percha
– 0 - 1 month is “gray” area (retreat if unsure)
Cases w/ poor prognosis for NS ret
• Perforations (strip, furcal, or apical)
• Significant transportation or ledging
• Significant overfill
• Separated objects in apical canal space
• History of appropriate previous NS RETX
• Dilacerated roots and anatomical
variations
Inappropriate reasons for avoiding NS Retx
- Prefabricated posts
- Cast post and cores
- Solid core obturation material
- Amalgam retained core
- Radiographically well-obturated canal
Prognosis of NS ret
Retx always less % successful than initial
Good candidates
- Weak fill, visible space along and apical to fill
Rationale for
Non-Surgical RETX
• Relatively ‘easy’ – Access – Techniques easier to master • Theoretically more successful – Remove bacteria vs corking them inside • Clinically more successful? – Retreatment : > 80% – Surgery: ~ 70% Historic • Modern Techniques ~90%
Indications for Surgical TX
• Previous non-surgical retreat unsuccessful
• Blocked coronal approach or access problems
• Desire for apical inspection or biopsy
• Probability of non-surgical success deemed poor
(perf, ledge, etc)
• Monetary considerations (destruction of post, core, and
crown).
• Patient’s loss of trust in non-surgical approach
Contraindications for
Surgical RETX
- Patient’s medical health problems
- Lack of operator skills
- Patient’s inability to tolerate or accept surgery
- Anatomical considerations
- Non-surgical RCT has not been attempted
Modified Access for
Retreatment
• Complete removal of existing crown – Significantly improves access – Consider effect on isolation • Enlarged access – Especially important through existing restorations – Maintain peripheral tooth structure – Allows use of Steiglitz, post pullers, etc – Assume that a core material is present
Gutta-Percha
Retreatment in weak fills
• Attempt bulk removal of weak fills
– Ultrasonic files to break cement
Ultrasonics
– Quickly loosens and flushes materials in canal
– Must use carefully to avoid ledge formation
– Removes sealer, cement, and debris remaining
on walls
– Not good for path-finding
– Remove gutta-percha with Steiglitz
forceps
First step in GP rem
Heat Source first
– Remove GP as far down canal as possible
Using gates and peeso to rem GP
– Only in straight portion of canal
– Removes bulk of coronal material
• GPX, K3 or other rotary systems and GP rem
– Careful use in curved canals
– Can remove all material to WL
• Hedstrom and standard hand files in GP rem
remove remaining apical material
– Screw into gutta-percha and pull
– Watch out for transportation of canal
Chemical Softening of GP
– Used as adjunct with other techniques – Use with care in the last 3 mm of canal to avoid extrusion – Choices include: •Chloroform - may not always be available •Halothane - slower than chloroform but works well •Historically - Eucalyptol, Turpentine
Chemical Softening Technique
– Flood canal and chamber (rapid evaporation)
– Use files to remove softened material
– Some brands of gutta-percha not soluble
– May help dissolve sealers, cements, and pastes
– TB syringe with Choroform / Halothane
Paste Fill Retx
• Soft Paste – Ultrasonic file •Pre-bend •Place to WL before activating •Quickly flushes paste from canal • Hard Paste – Chemical softening (Halothane) may work – Ultrasonics, but ledge formation may occur
Thermafil Plastic
Retreatment
• Careful access to maintain tip of carrier
• Ultrasonics or file to create path or break seal
• Attempt bulk removal with Steiglitz
• Chemical softening (Chloroform / Halothane)
– Thermafil plastic carriers > size 40 are insoluble
– Thermafil plastic carriers ≤ size 40 are soluble
• Heat technique with Touch-N-Heat or
System B
• Rotary instruments
Removing Metal Obstructions
METAL CONES, CARRIERS, SEPARATED INSTRUMENTS
• Attempt to bypass and create space first
– small files w/bend at tip
• EDTA solution may help loosen dentin mud
• Ultrasonic file placed past obstruction
• Microscope with specialized endosonic tips
• Brassler Endo Extractor
• Braided file technique
Thermafil Metal
Retreatment
- Careful access to maintain tip of carrier
- Ultrasonics or file to create path or break seal
- Endosonic tip to vibrate metal carrier
- Heat application - Touch-n-Heat / System B
- Chemical softening
Should separated instruments be rem
• Crump and Natkin, 1970
– 53 matched pairs, no difference in success
– Location
– Degree of debridement
• Spilli et al, 2005
– Incidence 3-5%, no difference in success
• Souter, 2005
– Removal of files in apical and middle third significantly
weakened teeth
– 4/15 apical to start of curvature failed
CONCLUSION: No need to routinely remove fx instruments in apical third
SILVER CONE
Retreatment
• Access is critical
– Careful removal of material around tip of cones
• Specialized ultrasonic tips to chip away material
• Ultrasonic file to break cement bond
• Extract cone
– Steiglitz, Caulfield spoon, Hemostat,
combination
– Application of ultrasonic scaler tip to
instrument
What bur(s) might be useful in post rem
LN or
Mueller
Bur
Brassler Endodontic
BrasslerE Exntdroadcotnotric
- Useful if object can be visualized
- Estimate size of object and choose extractor
- Trephine bur to create space around object
- Cyanoacrylate in extractor
- Glue on extractor (allow 5 min minimum set)
- Pull extractor straight out (no rotation)
IRS Instrument Removal System
• Ruddle invention for use on intracanal
obstructions such as silver points, carrier-based
obturations or broken file segments.
• Black handled instrument features a 19-gauge
microtube and the smaller red handled
instrument has a 21-gauge microtube for deeper /
narrow canals.
IRS technique
– Microtube is placed over the obstruction
– Beveled edge helps to scoop the obstruction into
place within the tube
– Knurled handled wedge is threaded into the
microtube
– Wedge grabs onto the obstruction and allows it to
be pulled free of the canal.
Lasso Technique
– Ortho ligature wire is threaded through a 21-25 gauge
needle and a small loop is made that approximates the size
of the canal obstruction to be retrieved
– The needle is placed beside the obstruction and the
lasso/noose is slipped over the object
– Gently begin to wind the excess wire extending through the
opposite end of the needle to tighten the lasso around the
head of the obstruction
– Tug or tap the entire apparatus out of the canal, removing
the obstruction
Braided File Technique
• Create at least 2 separate paths around object • EDTA may help soften dentin walls • Place 2 or 3 #15 - 25 Hedstrom files past object • Twist handles to braid files • Grab twisted files with hemostat and pull straight out • Simultaneous Ultrasonics ?
Post rem
• Ultrasonics
– Endosonic tips “jackhammer” away cement
– Create path (usually buccal or lingual surface)
– Scaler tip to vibrate post loose
– Consider chemical softening of cement
• Gonon / Ruddle Systems
– Very effective, but expensive and may be slow
– Works with a wide variety of post systems
Thomas Screw (Gonon) Post Extractor
- Compatable sized Trephines & Taps
- Clockwise Rotation
- Extension tubes for anterior teeth
- Avoid torque - i.e. straight-line extraction
Thomas screw technique
1. “Pointer drill” to help center trephine bur 2. Trephine bur preparing at least 1 - 2 mm of post 3. Tap post with matching size tap. Assure tight fit 4. Assemble washers onto tap and rethread tap to post 5. Place post extractor onto tap, support weight with hand 6. Begin turning, allowing pause between quarter turns when resistance begins
Ruddle Post Removal
System
• Counterclockwise Rotation - unscrew threaded posts
• Extra smaller sized
trephine & tap
For All Retreatment
Cases
• Consider two-visit treatment with Ca(OH)2
– Aids in dissolution of any remaining debris
– Helps to kill bacteria in mechanically
inaccessible locations
• Copious NaOCl irrigation
• Thorough ultrasonic flush
• Concepsis (2% CHX)
Good Prognosis for
Retreatment if…
• Poor density of obturation
• Under-prepared canals (silver cone,
Thermafil)
• Short fill with visible canal space apically
• Visible or suspected missed canal
– MB root of max. molar (50-90% with two canals)
– D root of man. molars (29% with two canals)
– Lower incisors (42% with two canals)
How to get prognosis
• Determine cause for failure in each case
– If cause is corrected - prognosis is good
– If no cause found - prognosis is guarded
• May only need slight change in canal
environment to stimulate healing
Factors that affect success
Only • 47% if root canal anatomy altered Only • 62% heal with a lesion – Significant factors reducing healing • PA lesion • Apical extent of RC filling • Quality of coronal restoration Overall success 80%
Endo Retx traps
- Hopeless perio
- Non-restorable teeth
- Vertical root fractures
- Missed diagnosis (wrong tooth)
- Cases you have little or no chance of improving
