endodontic failures endodontic failures

and retreatmentand retreatment

Introdution

• In different studies success rate ranges from 54 percent to 95 percent.

• The definition of success is ambiguous

- stringent : radiographic and clinical normalcy

- lenient : only clinical normalcy

Endodontic treatment outcome

• Healed: both clinical and radiographic presentations are normal• Healing: it’s a dynamic process, reduced radiolucency combined with normal clinical presentation• Disease: No change or increase in radiolucency, clinical

signs may or may not be present or vice versa

Evaluation of success

• Success or failures following endodontic therapy could be evaluated from combination of clinical, histopathological and radio graphical criteria.

Clinical evaluation for success

• No tenderness to percussion or palpation

• Normal tooth mobility

• No evidence of subjective discomfort

• Tooth having normal form, function and aesthetics

• No sign of infection or swelling

• No sinus tract or integrated periodontal disease

• Minimal to no scarring or discoloration

Radiographic evaluation for success

• Normal or slightly thickened periodontal ligament space

• Reduction or elimination of previous rarefaction

• No evidence of resorption

• Normal lamina dura

• A dense three dimensional obturation of canal space

Histological evaluation for success

• Absence of inflammation

• Regeneration of periodontal ligament fibers

• Presence of osseous repair

• Repair of cementum

• Absence of resorption

• Repair of previously resorbed areas

Causes of the endodontic failures

Bacteria somewhere in the root canal system Divided into local and systemic

Factors affecting success or failure of endodontic therapy

in every case

• Diagnosis and the treatment planning• Radiographic interpretation• Anatomy of the tooth and root canal system• Debridement of the root canal space

Factors affecting success or failure of endodontic therapy

in every case

• Quality and extent of apical seal• Quality of post endodontic restoration• Systemic health of the patient• Skill of the operator

Factors affecting success or failure of a particular case Factors

affecting success or failure of a particular case

• Pupal and Periodontal status• Size of periapical radioleucency• Canal anatomy • Crown and root fracture

Factors affecting success or failure of a particular case Factors

affecting success or failure of a particular case

• Iatrogenic errors• Extent and quality of the obturation• Quality of the post endodontic restoration• Time of post treatment evaluation

Local Factors causing endodontic failures

• Infection

• Incomplete debridement of the root canal system

• Excessive hemorrhage

• Chemical irritants

• Iatrogenic errors

Infection

• infected and necrotic pulp tissue→main irritant to the periapical tissues

• The host parasite relationship 、 virulence of microorganisms , ability of infected tissues to heal→influence the repair of the periapical tissues

• Endo success →debridement

Incomplete debridement of the root canal system

• Main objective of root canal therapy→complete elimination

of the microorganisms and their

byproducts

• Poor debridement → residual

microorganisms 、 byproducts and

tissue debris → recolonize

Excessive hemorrhage

• Extirpation of pulp and instrumentation beyond periapical tissues

• Local accumulation of the blood→mild inflammation

• Extravasated blood cells and fluid ： foreign body nidus for bacterial growth

Over instrumentation

• Instrumentation beyond apical foramen→PDL and alveolar bone trauma→the prognosis of endodontic treatment ↓

Chemical irritants

• Intracanal medicaments and irrigating solution

→extruded in the periapical tissues→the prognosis of endodontic treatment ↓

• One should take care while Using medicaments to avoid their periapical

extrusion

Iatrogenic errors

• Separated instruments—

• Caused by improper or overuse of

• instruments and forcing them in curved

canals

• Prognosis ： no much affected in vital pulps

poor in necrotic tissue.

Iatrogenic errors• Canal blockage and ledge formation—

• Accumulation of dentin chips or tissue debris

prevent the instruments to reach its

full working length

• Ledge formation—straight instruments in

curved canals

• These lead to bacteria & debris remained

endo failure

Iatrogenic errors

• Perforations—

• Lack of knowledge of anatomy of the tooth,

attention, misdirection of the instruments

• Prognosis ： location, time, perforation seal and size

• Poor prognosis remaining

infected tissue

Iatrogenic errors• Incompletely filled teeth—• Teeth filled more than 2mm short of apex• Several studies shown ：• poor prognosis—underfillings with necrotic

pulps • Overfilling of root canals—• Overfilling extending ≧ 2mm beyond • radiographic apex• Continuous irritation of the periapical • tissues endo failure

Iatrogenic errors

• Anatomic factors—

• Such as ： overly curved canals, calcifications,

• numerous lateral and accessory canals,

• bifurcations, C or S shaped canals

• Problems in cleaning and shaping &

• incomplete filling of root canals

• endodontic failure

Iatrogenic errors

• Root fractures—• Partial or complete fractures of roots• Prognosis of teeth ：• vertical root is poor than horizontal fractures• Traumatic occlusion –• Cause endo failures because of its effect on • periodontium

Systemic factors causing endodontic failures

• Nutritional deficiencies

• Diabetes mellitus• Renal failure• Blood dyscrasias• Hormonal imbalance

• Autoimmune disorders• Opportunistic

infections• Aging• Long term steroid

therapy

Endodontic retreatment

Before going/performing Case selection Prognosis ,Contraindications and problems Steps

Before going to endodontic retreatment

• when should Treatment be considered

• Patient’s needs

• Strategic importance of the tooth

• Periodontal evaluation of the tooth

• Chair time & cost

Before performing to endodontic retreatment

• May to prevent the potential disease

• Remove/remade extensive coronal restoration

• Technical problems

• May not achieve better results

• Filling materials have to be removed

• Prognosis could be poorer

• Patient might be more apprehensive

Case selection

• Careful history

• Anatomy of root canal , canal curvature, calcifications,unusual configurations

• Quality of obturation

• Iatrogenic complications

• Cooperation of the patient

Factors affecting prognosis of endodontic treatment

• Periapical radiolucency• Quality of the obturation• Apical extension of the obturation material• Bacterial status• Observation period• Postendodontic coronal restoration• Iatrogenic complication

Contraindications of endodontic retreatment

• Unfavorable root anatomy

• Untreatable root resorptions or perforations

• Root or bifurcation caries

• Insufficient crown/root ratio

Problems of endodontic retreatment

• Unpredictable result

• Frustration

• Cost factor

• Time consuming

Steps of Retreatment

1. Coronal disassembly2. Establish access to root canal system3. Remove canal obstructions4. Establish patency5. Thorough cleaning, shaping and obturation of

the canal

1. Coronal Disassembly• Removal of existing

coronal restoration• Access made through

coronal restoration

Advantages of gaining access through original restoration:

a. Facilitate rubber dam placement

b. Maintaining form, function and aesthetics

c. Reducing the

cost of replacement

Disadvantages of retaining a restoration:

a. Reduce visibility and accessibility

b. Increased risks of irreparable errors

c. Increased risks of microbial infection if crown margins are poorly adapted

Advice:Remove the existing restorationEspecially: poor marginal adaptation, secondary cariesPlace temporary crown to maintain form, function and aesthetics.

2. Establish Access to Root Canal System

Teeth restored with post and core:1.Post and core need to be removed for gaining access to root canal system2.Post and core can be perforated to gain access

Posts can be removed by:

1. Weakening retention of posts by use of ultrasonic vibration.2. Forceful pulling of posts but it increases the risk

of root fracture3. Removing posts with the help of special pliers

using post removal systems

Post Removal System(PRS)

Post Removal System(PRS)

• 5 various designed trephines

• Corresponding taps(microtubular tap)

• Torque bar

• Transmetal bur

• Rubber bumpers

• Extracting plier

1-Transmental bur

Effeciently dooming of the post head

2-Add lubricant

• EX: RC Prep

• Be placed on the post head to further facilitate the machining process

3-Trephine bur

Use the largest bur to machine down

the coronal 2-3 mm of the post.

4-Rubber bumper inserted on the tab & pushed on the occlusal

surface.

Act as a cushion, distribute the loads and protect thetooth during the removal

procedure.

5-Microtubular tap

• Inserted against the post head.

• Screwed it into post with counter clockwise direction and strongly engage the post.

Post removal plier

• Mount the post removal plier on tubular tap

• Ultrasonic instrument using/torque bar inserting

plier

Tubular tap

Rubber bumper

Screw knob

Ultrasonic instrument

1 -Nonsurgical Removal of Posts Broken Instruments - YouTube_x264.mp4

Post removal plier

Removing Canal Obstructions and

Establishing Patency

Silver Point Removal

A- Microsurgical forceps

Silver point removal

B-Ultrasonic

Siver point removal

C- Using Hedstroem files(H-files)

Silver Point Removal

E- Post removal system kit.

D- Instrument removal system(IRS).

Gutta-Percha Removal• The relative difficulty in removing gutta-percha is

influenced by some factors of canal system: Length Diameter Curvature Internal configuration

• Progressive Manner : gutta-percha is best removed from canal in

progressive manner to prevent its extrusion periapically

Gutta-Percha Removal• Coronal portion of gutta-percha should always be

explored by Gates-Gliddens to:Quickly : Remove gutta-percha quicklySolvent : Provide space for solventsConvenience : Improve convenience form

• Gutta-percha can be removed by using:SolventsHand instrumentsRotary instrumentsMicrodebrider

1. Solvents

• GP is soluble in:Chloroform ： most effective but carcinogenic with

high concentratin , excessive filling in pulp chamber is avoided

Methyl chloroformBenzeneXyleneEucalyptol oilHalothane

• GP dissolution should be supplemented by using hand instruments

2. Hand Instruments Used mainly in apical portion of the canal.

• Hedstroem files

• Hot endodontic instrument like Reamer or files

Poorly condenced GP can be pulled easily

3. Rotary Instruments•They are Safe to be used in straight canals

Recently:

•ProTaper universal systemsConsisting of file :D1 D2 D3500-700 rpm

Protaper universal system

• D1 :

Remove filling from the coronal third

• D2 :

Remove filling from the middle third

• D3 :

Remove filling from appical third

Microdebriders

A small files with 90 degrees bends Removing remaining gutta-percha on the sides

of canal walls

Pastes and Cement

Soft setting pastes Penetrated by endodontic instruments

Hard setting cements Softened by solvents: xylene, eucalyptol......

Then removed by files . Ultrasonic devices

Separated Instruments and Foreign Objects

Coronal third – attempt retrieval Middle third – attempt retrieval or bypass Apical third – surgical treat

Separated Instruments and Foreign Objects

Attempt retrieval Mechanism → Stieglitz pliers, Massermann

extractor Vibration → Ultrasonics Accessibility → Modified Gates Glidden

bur Bypass

Reamers or files with copious irrigation Surgical treat

Apicoectomy

Ultrasonic

4-endo(instrument removal) - YouTube_x264.mp4

Instrument removal system (IRS)Can be used to remove the broken

files

microtube screw wedge

The beveled end of the microtube oriented toward the outer wall of the canal to “scoop up” the head of the broken file.

The introduction of the screw wedge which is rotated CCW to engage and displace the head of the file out the side window.

Completion of the Retreatment

Thorough cleaning, shaping and obturation The outcome of retreatment

Short-term: no pain and swelling Long-term: depended regaining canal patency &

obturation of the root canal system Retreatment is mostly associated with procedural

complication. Effective communication is required b/t dentist & patient.