Endodontic Mishaps

R. HASSAN Assoc Prof of Endodontics

MUST Minia University Assuit University

PerforationsInstrumentation Mishaps

PerforationInstrumentation Mishaps

Cervical Mid root Apical

PerforationInstrumentation Mishaps

Cervical Mid root Apical

post prep Retreatment bybass inst

b. Midroot perforations

Tend to occur mostly in curved canals

Detected by the sudden appearance of hemorrhage in a previously dry canal or by a sudden complaint by the patient.

A paper point placed in the canal can confirm the presence and location of the perforation

Radiographs Electronic apex locators

Repair is difficult due to limited access Intentional replantation

Instrumentation Mishaps

330

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2. Using incremental filing technique.3. Using flexible files.4. Removing flutes of file at certain areas, for example, file

portion which makes contact with outer dentinal wall atthe apex and portion which makes contact with innerdentinal wall especially in the mid root area (Fig. 22.28).

5. Over curving in apical part of the file specially when workingfor severely curved canals.

STRIPPING OR LATERAL WALL PERFORATION“Stripping” is a lateral perforation caused by over instru-mentation through a thin wall in the root and is most likelyto happen on the inside or concave wall of a curved canal suchas distal wall of mesial roots in mandibular first molars (Fig.22.29). Stripping is easily detected by sudden appearance ofhemorrhage in a previously dry canal or by a sudden complaintby patient.

ManagementSuccessful repair of a stripping or perforation relies on theadequacy of the seal established by repair material.

Access to mid-root perforation is most often difficult andrepair is not predictable. Calcium hydroxide can be used as abiological barrier against which filling material is packed.

Repair of strip perforation can be done both non-surgicallyas well as surgically. Majority of techniques however proposeda two step method, where the root canal is first obturated anddefect is repaired surgically.

Prevention1. Use of pre-curved files for curved canals.2. Use of modified files for curved canals. A file can be

modified by removing flutes of file at certain areas, forexample, file portion which makes contact with outerdentinal wall at the apex and portion which makes contactwith inner dentinal wall especially in the mid-root area (Fig.22.29).

3. Using anticurvature filing, i.e. more filling pressure is placedon tooth structure away from the direction of rootcurvature and away from the invagination, therebypreventing root thinning and perforation of the rootstructure (Fig. 22.30).

CANAL TRANSPORTATION“Apical canal transportation is moving the position of canal’snormal anatomic foramen to a new location on external rootsurface” (Figs 22.31A to C).

In this case, root shows reverse architecture which is difficultto obturate, resulting in poor quality of obturation and thuscontributing to endodontic failures.

Canal transportations can be classified into three types, viz.Type I, II and III.

Type I: It is minor movement of physiologic foramen. In suchcases, if sufficient residual dentin can be maintained, one cantry to create positive apical canal architecture so as to improvethe prognosis of the tooth (Fig. 22.31A).

Type II: Apical transportation of Type II shows moderatemovement of the physiologic foramen to a new location (Fig.22.31B). Such cases compromise the prognosis and are difficultto treat. Biocompatible materials like MTA can be used toprovide barrier against which obturation material can be packed.

Fig. 22.28: Modification of flutes of file

Fig. 22.29: Strip perforation occurs more commonlyon inner side of curve

Fig. 22.30: Anticurvature filing

Strip perforation occurs more common on inner side of the curve

Over-preparation increases the chance of strip perforation(arrow) esp. on the inner side

of a curved canal

Strip perforation: Usually occurs in the mesio-buccal root of maxillary molars.

in the furcal aspect of coronal third of mesial roots of lower molars “danger zone”

due to excessive enlargement.

Strip perforationInstrumentation Mishaps

✴ Inflammation ✴ Periodontal pocket ✴ Attachment loss

Repair of a stripping perforation in the coronal third of the root has the poorest long-term prognosis of any type of perforation. The defect is usually inaccessible for adequate repair. An attempt should be made to seal the defect internally

✴ Inflammation ✴ Periodontal pocket ✴ Attachment loss

Strip perforation

Repair of a stripping perforation in the coronal third of the root has the poorest long-term prognosis of any type of perforation. The defect is usually inaccessible for adequate repair. An attempt should be made to seal the defect internally

Surgical Treatment

hemisection, bicuspidization, root amputation, and intentional replantation.

when the defect is inaccessible when multiple problems exist, such as a perforation combined with a separated instrument,

indications

Instrumentation Mishaps

c. Apical perforation

329

Procedural Accidents

PrognosisPrognosis of separated instrument depends upon followingfactors:a. Timing of separationb. Status of pulp tissuec. Position of separated instrumentd. Ability to retrieve or bypass the instrument.

Prevention1. Examine each instrument before placing it into the canal.

One should always discard instrument when there is:• Bending of instrument.• Corrosion of instrument• Unwinding of flutes.• Excessively heating of instrument• Dulling of NiTi instrument

2. Instead of using carbon steel, use stainless steel files.3. Use smaller number of instruments only once.4. Always use the instruments in sequential order.5. Never force the instrument into the canal.6. Canals should be copiously irrigated during cleaning and

shaping procedure.7. Never use instruments in dry canals.8. Always clean the instrument before placing it into the canal.

Debris collected between the flutes retard the cuttingefficiency and increase the frictional torque between theinstrument and canal wall.

9. Do not give excessive rotation to instrument while workingwith it.Studies have shown that instrument separation in root filled

teeth with necrotic pulps results in a poorer prognosis. But ifan instrument can be bypassed and incorporated in the rootcanal filling, prognosis becomes favorable. Also if instrumentseparates at later stages of instrumentation and close to apex,prognosis is better than if it separates in undebrided canals,short of the apex or beyond apical foramen. Separated instru-ment are not the prime cause of endodontic failure but separatedinstruments impede mechanical instrumentation of the canal,which may cause endodontic failure.

Before going for removal of broken instrument, evaluatethe tooth radiographically. Before starting with the instrumentretrieval efforts, one should ensure straight line access to thecanal orifice.

ZIPPINGZipping is defined as transposition of the apical portion of thecanal (Fig. 22.26).

EtiologyThis is commonly seen in curved canals because of followingreasons:1. Failure to precurve the files.2. Forcing instruments in curved canal3. Use of large, stiff instruments to bore out a curve canal.

In zipping, apical foramen tends to become a tear drop shapeor elliptical, is transported from the curve of the canal.

File placed in curved canal cuts more on the outer portionof the canal wall at its apical extent, thus causing movementof the canal away from the curve and its natural path. In contrast,the coronal third of the flutes remove more on the inner mostaspect of the canal wall causing an uneven reduction of thedentin in the coronal third.

When a file is rotated in a curved canal, a biomechanicaldefect known as an elbow is formed coronal to the ellipticallyshaped apical seat. This is the narrowest portion of the canal(Fig. 22.27). In many cases the obturating material terminatesat the elbow leaving an unfilled zipped canal apical to elbow.This is the common occurrence with laterally compacted gutta-percha technique. Use of vertical compaction of warm gutta-percha or thermoplasticized gutta-percha is ideal in these casesto compact a solid core material into the apical preparationwithout using excessive amount of sealer.

Elbow prevents optimal compaction in the apical portionof the canal. Since elbow becomes the apical seat, the obturatingmaterial is compacted against the elbow and patient is recalledor regular basis.Zipping can be prevented by:1. Using precurved files for curved canals.

Fig. 22.26: Zipping is transposition of apical portion of the canal

Fig. 22.27: Elbow formed in a curved canal

Zipping is transportation of apical portion of the canal

Recognition:

Patient suddenly complains of pain during treatment

Canal becomes flooded with hemorrhage

Tactile resistance of the confines of the canal space is lost

Instrumentation Mishaps

c. Apical perforation

329

Procedural Accidents

PrognosisPrognosis of separated instrument depends upon followingfactors:a. Timing of separationb. Status of pulp tissuec. Position of separated instrumentd. Ability to retrieve or bypass the instrument.

Prevention1. Examine each instrument before placing it into the canal.

One should always discard instrument when there is:• Bending of instrument.• Corrosion of instrument• Unwinding of flutes.• Excessively heating of instrument• Dulling of NiTi instrument

2. Instead of using carbon steel, use stainless steel files.3. Use smaller number of instruments only once.4. Always use the instruments in sequential order.5. Never force the instrument into the canal.6. Canals should be copiously irrigated during cleaning and

shaping procedure.7. Never use instruments in dry canals.8. Always clean the instrument before placing it into the canal.

Debris collected between the flutes retard the cuttingefficiency and increase the frictional torque between theinstrument and canal wall.

9. Do not give excessive rotation to instrument while workingwith it.Studies have shown that instrument separation in root filled

teeth with necrotic pulps results in a poorer prognosis. But ifan instrument can be bypassed and incorporated in the rootcanal filling, prognosis becomes favorable. Also if instrumentseparates at later stages of instrumentation and close to apex,prognosis is better than if it separates in undebrided canals,short of the apex or beyond apical foramen. Separated instru-ment are not the prime cause of endodontic failure but separatedinstruments impede mechanical instrumentation of the canal,which may cause endodontic failure.

Before going for removal of broken instrument, evaluatethe tooth radiographically. Before starting with the instrumentretrieval efforts, one should ensure straight line access to thecanal orifice.

ZIPPINGZipping is defined as transposition of the apical portion of thecanal (Fig. 22.26).

EtiologyThis is commonly seen in curved canals because of followingreasons:1. Failure to precurve the files.2. Forcing instruments in curved canal3. Use of large, stiff instruments to bore out a curve canal.

In zipping, apical foramen tends to become a tear drop shapeor elliptical, is transported from the curve of the canal.

File placed in curved canal cuts more on the outer portionof the canal wall at its apical extent, thus causing movementof the canal away from the curve and its natural path. In contrast,the coronal third of the flutes remove more on the inner mostaspect of the canal wall causing an uneven reduction of thedentin in the coronal third.

When a file is rotated in a curved canal, a biomechanicaldefect known as an elbow is formed coronal to the ellipticallyshaped apical seat. This is the narrowest portion of the canal(Fig. 22.27). In many cases the obturating material terminatesat the elbow leaving an unfilled zipped canal apical to elbow.This is the common occurrence with laterally compacted gutta-percha technique. Use of vertical compaction of warm gutta-percha or thermoplasticized gutta-percha is ideal in these casesto compact a solid core material into the apical preparationwithout using excessive amount of sealer.

Elbow prevents optimal compaction in the apical portionof the canal. Since elbow becomes the apical seat, the obturatingmaterial is compacted against the elbow and patient is recalledor regular basis.Zipping can be prevented by:1. Using precurved files for curved canals.

Fig. 22.26: Zipping is transposition of apical portion of the canal

Fig. 22.27: Elbow formed in a curved canal

Zipping is transportation of apical portion of the canal

Recognition:

Patient suddenly complains of pain during treatment

Canal becomes flooded with hemorrhage

Tactile resistance of the confines of the canal space is lost

Prevention

Maintaining proper wl through ttt

Flexible files in curved canals

Instrumentation Mishaps

c. Apical perforation

329

Procedural Accidents

PrognosisPrognosis of separated instrument depends upon followingfactors:a. Timing of separationb. Status of pulp tissuec. Position of separated instrumentd. Ability to retrieve or bypass the instrument.

Prevention1. Examine each instrument before placing it into the canal.

One should always discard instrument when there is:• Bending of instrument.• Corrosion of instrument• Unwinding of flutes.• Excessively heating of instrument• Dulling of NiTi instrument

2. Instead of using carbon steel, use stainless steel files.3. Use smaller number of instruments only once.4. Always use the instruments in sequential order.5. Never force the instrument into the canal.6. Canals should be copiously irrigated during cleaning and

shaping procedure.7. Never use instruments in dry canals.8. Always clean the instrument before placing it into the canal.

Debris collected between the flutes retard the cuttingefficiency and increase the frictional torque between theinstrument and canal wall.

9. Do not give excessive rotation to instrument while workingwith it.Studies have shown that instrument separation in root filled

teeth with necrotic pulps results in a poorer prognosis. But ifan instrument can be bypassed and incorporated in the rootcanal filling, prognosis becomes favorable. Also if instrumentseparates at later stages of instrumentation and close to apex,prognosis is better than if it separates in undebrided canals,short of the apex or beyond apical foramen. Separated instru-ment are not the prime cause of endodontic failure but separatedinstruments impede mechanical instrumentation of the canal,which may cause endodontic failure.

Before going for removal of broken instrument, evaluatethe tooth radiographically. Before starting with the instrumentretrieval efforts, one should ensure straight line access to thecanal orifice.

ZIPPINGZipping is defined as transposition of the apical portion of thecanal (Fig. 22.26).

EtiologyThis is commonly seen in curved canals because of followingreasons:1. Failure to precurve the files.2. Forcing instruments in curved canal3. Use of large, stiff instruments to bore out a curve canal.

In zipping, apical foramen tends to become a tear drop shapeor elliptical, is transported from the curve of the canal.

File placed in curved canal cuts more on the outer portionof the canal wall at its apical extent, thus causing movementof the canal away from the curve and its natural path. In contrast,the coronal third of the flutes remove more on the inner mostaspect of the canal wall causing an uneven reduction of thedentin in the coronal third.

When a file is rotated in a curved canal, a biomechanicaldefect known as an elbow is formed coronal to the ellipticallyshaped apical seat. This is the narrowest portion of the canal(Fig. 22.27). In many cases the obturating material terminatesat the elbow leaving an unfilled zipped canal apical to elbow.This is the common occurrence with laterally compacted gutta-percha technique. Use of vertical compaction of warm gutta-percha or thermoplasticized gutta-percha is ideal in these casesto compact a solid core material into the apical preparationwithout using excessive amount of sealer.

Elbow prevents optimal compaction in the apical portionof the canal. Since elbow becomes the apical seat, the obturatingmaterial is compacted against the elbow and patient is recalledor regular basis.Zipping can be prevented by:1. Using precurved files for curved canals.

Fig. 22.26: Zipping is transposition of apical portion of the canal

Fig. 22.27: Elbow formed in a curved canal

Zipping is transportation of apical portion of the canal

Recognition:

Patient suddenly complains of pain during treatment

Canal becomes flooded with hemorrhage

Tactile resistance of the confines of the canal space is lost

Prevention

Maintaining proper wl through ttt

Flexible files in curved canalsTREATMENT ESTABLISH NEW WL 1-2 mm SHORTER,CREAT APICAL SEAL

MTA APICAL BARRIER

Apicectomy (zipping)

Artificial apical barrier technique

Apicectomy (zipping)

Obturation Mishaps

Over & under-extended fillingsObturation Mishaps

Over extended Apical perforation

False IFA

Underextended Poor W.L.

Poor canal prep. blockage

Detected by R.G.

Good working length. Create apical stop.

Blockage

Correction Under filling:

Removal of G.P. Over filling:

Retrieval/Surgical

331

Procedural A

ccidents

Type III: Apical transportation of Type III shows severemovement of physiological foramen (Fig. 22.31C). In such type,prognosis is poorest when compared to Type I and Type II.A three dimensional obturation is difficult in such cases. Thisrequires surgical intervention for correction otherwise toothis indicated for extraction.

INADEQUATE CANAL PREPARATION

Over InstrumentationExcessive instrumentation beyond the apical constrictionviolates the periodontal ligament and alveolar bone. Loss ofapical constriction creates an open apex with an increased riskof overfilling, lack of an adequate apical seal (Fig 22.32), painand discomfort for the patient.

Over instrumentation is recognized when hemorrhage isevident in the apical portion of canal with or without patientdiscomfort (Fig. 22.33) and when tactile resistance of theboundaries of canal space is lost. It can be confirmed by takinga radiograph and by inserting paper point in the canal (Fig.22.34).

TreatmentTreatment includes re-establishing tooth length short of theoriginal length and then enlarging the canal, with largerinstruments, to that length. The canal is then carefully filledto established working length so as to prevent extrusion ofthe filling beyond apex (Figs 22.35A and B).

Another technique which can be employed to prevent overextrusion of the filling is creating an apical barrier. Materialsused for developing such barrier include dentin chips, calciumhydroxide powder, hydroxyapatite and more recently MTA.

PreventionOver instrumentation beyond apical constriction can beprevented by:1. Using good radiographic techniques.

Figs 22.31A to C: Type I, II and III canal transportation (A) Minormovement of apical foramen (Type I) (B) Moderate movement of apicalforamen (Type II) (C) Severe movement of apical foramen (Type III)

Fig. 22.32: Radiograph showing instrumentgoing beyond periapex

Fig. 22.33: Excessiveinstrumentation

Figs 22.35A and B: Overfilling of the canalcausing irritation to periapical area

Fig. 22.34: Paper point showinghemorrhage at the tip

BA

Over filling of the canal causing irritation to preiapical area

Over-extended fillingsCauses: 1-Apicalperforation2-Toomuchcondensationforce3-Lossofapicalconstriction-openapex,resorptionetc.

May result in treatment failure by:

IrritationfromfillingmaterialLeakageCompressionofneurovascularbundle&neurotoxicity

Obturation Mishaps

Causes: Incorrect working length Failure to fit master cone up to working length Improper canal preparation particularly in apical part

May result in treatment failure by: Persistent infection Reinfection and apical percolation of tissue fluids

Under-extended fillingsObturation Mishaps

Vertical root fractureIncreased pressure during

lateral condensation increased apical pressure during post cementation

Single root > Extraction Multi rooted > Root resection

Sharp sound pain

bleeding loss of resistance against lateral condensation

R.L. along side of the V.F.

Obturation Mishaps

Nerve ParathesiaGross over extended fillings Formaldehyde containing sealers Surgical procedures Apical perforation with files

detected by patients complaint

observation Cortisone ttt

Obturation Mishaps

Post space perforationMis directed post space preparation ttt as perforation seen before Recognition by bleeding/radiograph.

Miscellaneous mishaps

Wedging of the needle in canal.

Forceful injection.

Detection:

immediate Swelling,

sudden sharp pain

ecchymosis.

Hypochlorite accidentWedging of the needle in canal.

Forceful injection.

Detection:

immediate Swelling,

sudden sharp pain

ecchymosis.

Treatment: Symptomatic treatment with analgesics & antibiotics

− Antihistamines can also be helpful to reduce any allergic reaction

Ice pack application initially followed by warm saline soaks from next day

In severe cases- hospitalization & monitoring.

Prognosis:

Mostly favorable if treated immediately

Otherwise paresthesia.

Prevention:

Do not force irrigant

Irrigating needle should not bind in the canal

Use Special irrigating needles such as side vent needles

Treatment: Symptomatic treatment with analgesics & antibiotics

− Antihistamines can also be helpful to reduce any allergic reaction

Ice pack application initially followed by warm saline soaks from next day

In severe cases- hospitalization & monitoring.

Prognosis:

Mostly favorable if treated immediately

Otherwise paresthesia.

Prevention:

Do not force irrigant

Irrigating needle should not bind in the canal

Use Special irrigating needles such as side vent needles

Endodontic Mishaps 231

Figure 8-14 A and B, Severe tissue emphysema caused by injecting hydrogenperoxide irrigant into the tissues. Courtesy of K.S. Bhat.

Figure 8-15 ProRinse needles (Dentsply/Tulsa) that irrigate through a side venteliminate the possibility of puncturing the apical foramen or the “watercannon” effect from open-ended needles.

exerted on the plunger of the syringe. Moreover, if a patient warnsthe dentist of an allergy to household bleach, substitiute chloram-phenicol or Bio Pure MTAD, (Dentsply/Tulsa Dental).

Tissue emphsimaCauses:

Blast of air

During surgery

Forceful injection of H2O2

Detection:

rapid Swelling.

Dysphagia, dysnea, Crepitus.

Correction:

Clearance the airway.

Antibiotics.

Prevention:

1) Paper point to dry canal.2) Use of special hand-piece in surgery

(impact air 45).

Col lection of gas/air in to subcutaneous/ periradicular tissues

The common etiologic factor is compressed air being forced into the tissue spaces- during canal p r e p a r a t i o n o r s u r g i c a l procedures

Instrument aspiration

Instrument aspiration

Causes:

Failure to use Rubber Dam

Recognition:

Patient’s symptoms

Chest & Abdomen Radiographs

Management:

Immediately hospitalized the patient

Prevention:

Use rubber dam strictly

Attaching floss to the clamps, files, reamers.

Instrument aspiration

87% of these instruments are swallowed and the rest are aspirated.

Surgical removal is required for some swallowed and nearly all aspirated instruments.

GOOD LUCK thank you