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Procedural accidents in root canal treatment last one
When an accident occurs during root canal treatment, thepatient should be informed about:(1) the incident.(2) procedures necessary for correction,(3)alternative treatment modalities.(4) the effect of this accident on prognosis.
In addition, the practitioner who knows his or her limitations willrecognize potentially difficult cases and will refer the patient to an endodontist.
Accidents During Access PreparationAccidents During Cleaning and ShapingAccidents During ObturationACCIDENTS DURING POST SPACEPREPARATION
Classification of Procedural AccidentsAccidents During Access Preparation• Perforations During Access Accidents During Obturation Preparation •Underfilling• Causes •Overfilling• Prevention •Vertical Root Fracture• Recognition and Treatment• Prognosis Accidents During Post SpaceAccidents During Cleaning and Shaping Preparation• Ledge formation •I ndicators• Cervical canal perforations •Treatment and Prognosis• Midroot perforations• Apical perforations• Separated instruments and foreign objects• Canal blockage
Perforations During Access Preparation The prime objective of an access cavity is to provide an unobstructed or straight-line pathway to the apical foramen. Accidents such as excess removal of tooth structure or perforation may occur during attempts to locate canals. Failure to achieve straight-line access is often the main etiologic factor for other types of intracanal accidents. Perforations must be recognized early to avoid subsequent damage to the periodontal tissues with intracanal instruments and irrigants.
PerforationsThere are two types:1. Lateral root perforation 2. Furcation perforation
Causes1. Failure to direct the bur parallel to the long axis of the tooth.2. Searching for canals through an underprepared access cavity.3. Access through a small or flattened (disk-like) pulp chamber in a multirooted tooth.4. Access through a cast crown often is not aligned in the long axis of the tooth.
PreventionClinical examination1. Thorough knowledge of tooth morphology and outlines of the access cavities .2. Identification of tooth angulation according to the adjacent teeth.3. Proper reading of the preoperative (diagnostic) radiograph to get information about the size and extent of the pulp chamber and internal changes (calcification or resorption).4. Radiograph from different angles .
Bur held alongside radiograph to estimate the depthof penetration
Operative procedures1. Access without rubber dam or using “split technique” is preferred in specific cases2. Use of fiberoptic light and magnifiers3. Removal of restorations when possible Split dam technique
Recognition1. Sudden pain2. Sudden hemorrhage3. Radiograph4. Apex locator5. Taste of irrigant during irrigation
TreatmentLateral root perforationA- Perforation at or above the height of crestal boneTreatment: restorative treatment Supracrestal perforation repair
B- Perforation below the height of crestal bone in the coronal third of the rootThe treatment goal is to position the apical portion of thedefect above crestal bone by orthodontic extrusion or crownlengthening .Internal repair by mineral trioxide aggregate (MTA) is alsopossible .
Furcation perforationA- Direct perforationTreatment: immediate sealing using the suitable restorativematerial (MTA) Furcation repair using mineral trioxide aggregate (MTA)
B- Stripping perforation- Usually results from excessive flaring with files or drills (Gates Glidden)- Treatment: non-surgical treatment by immediate sealing using MTA surgical treatment: hemisection, bicuspidization, and root amputation
Nonsurgical Treatment1. The site of the perforation must be found,2. the floor of the preparation cleansed,3. the bleeding stopped,4. mineral trioxide aggregate (MTA) applied to the perforation .5. Because it takes MTA more than 3 hours to set, it should be covered with a fast-setting cement.6. The other canal orifices should be protected by placing paper points or an instrument in the canals to prevent blockage.
In the event MTA cannot be immediately applied,A. it is best to stop the bleeding,B. place calcium hydroxide over the “wound,”C. place a good temporary filling,D. set an appointment with the patient, the sooner the better.E. The perforation area will be dry at the next appointment;F. MTA can be appliedG. treatment continued.
Surgical TreatmentSurgery treatment requires:-1. more complex restorative procedures .2. more demanding oral hygiene from the patient.‘ Surgical alternatives are hemisection, bicuspidization,root amputation, and intentional replantation.Indicated:1.when the defect is inaccessible.2.when multiple problems exist, such as a perforationcombined with a separated instrument.3. when the prognosis with other surgical procedures ispoor .
Dentist and patient must recognize that theprognosis for treatment of surgically alteredteeth is guarded because of the increasedtechnical difficulty associated with restorativeprocedures and demanding oral hygienerequirements.
PROGNOSISFactors affecting the long-term prognosis of teeth afterperforation repair include:-1. the location of the defect in relation to crestal bone.2. the accessibility for repair.3. the size of the defect.4. the presence or absence of a periodontal communication to the defect.5. the time between perforation and repair.6. the sealing ability of restorative material.7. subjective factors such as:- I. the technical competence of the dentist. II. The attitude and oral hygiene of the patient
Treatment of the Wrong Tooth• Treatment of the wrong tooth can be so easily prevented. One should make sure through testing, examining, and radiography that one has confirmed which tooth requires treatment• Open the access cavity before applying the rubber dam
Damage to an Existing Restoration• Porcelain crowns are the most susceptible to chipping and fracture.• When one is present, use a water- cooled, smooth diamond point and do not force the bur, let it cut its own way .• Also, do not place a rubber dam clamp on the gingiva of any porcelain or porcelain-faced crown
Missed Canals• Additional canals in the mesial roots of maxillary molars and the distal roots of mandibular molars are the most frequently missed.• Second canals in lower incisors, and second canals in lower premolars, as well as third canals in upper premolars are also missed.• One must be prepare adequate occlusal access.
Ledge FormationDefinitiona ledge has been created when the working length can not longer be negotiated and the original patency of the canal is lost.
Causes1. inadequate straight-line access into the canal.2. inadequate irrigation or lubrication.3. excessive enlargement of a curved canal with files.4. packing debris in the apical portion of the canal.
Technical procedures: Straight line access. Accurate working length measurement . Frequent recapitulation and irrigation. Use of lubricant like RC-PREP. Use of flexible Ni-Ti files in curved canals . Each file must be used until it is loose before a larger size is used . Avoid application of severe forces during instrumentation .
Management of ledge• A ledge is difficult to correct.• An initial attempt should be made to bypass the ledge with a No. 10 steel file to regain working length.• The file tip (2 to 3 mm) is sharply bent and worked in the canal in the direction of the canal curvature.• Lubricants are helpful.• If the original canal is located, the file is then worked with a reaming motion and occasionally an up-and-down movement to maintain the space and remove debris• If the original canal cannot be located by this method, cleaning and shaping of the existing canal space is completed at the new working length.
PrognosisThe failure depends on the amount of debris left in the uninstrumented and unfilled portion of the canal.The amount depends on when ledge formation occurred during instrumentation.In general, short and cleaned apical ledges have good prognoses. Future appearance of clinical symptoms or radiographic evidence of failure may require referral for apical surgery or retreatment.
Root PerforationsApical perforationTypesA. Apical perforation through the apical foramen (overinstrumentation)
B- Apical perforation through the body of the root in the apical third Ledge apical perforation
Etiologya. Apical perforation through the apical foramen:- It is caused by instrumentation of the canal beyond the apical constriction (incorrect working length)b. Apical perforation through the body of the root in the apical third:- It is caused as a result of operator insistence to manage a ledge in the apical third (especially in curved canals)
Indicators1. Hemorrhage in the canal2. Bleeding at the tip of paper point3. Sudden pain4. Sudden loss of the apical stop5. Radiograph Bleeding at the tip of paper point
Prevention To prevent apical perforation, proper working lengths must be established and maintained throughout the procedure.
Treatment- In case of overinstrumentation, corrective treatment includes reestablishing tooth length short of the original length and then enlarging the canal, with larger instruments, to that length.- Placement of MTA as an apical barrier can prevent extrusion of obturation material- In case of apical perforation through the body of the root in the apical third, try to negotiate the original canal .
- One is now dealing with two foramina: one natural, the other iatral. Obturation of both of these foramina and of the main body of the canal requires the vertical compacting techniques with heat-softened gutta-percha
Non-surgical repair of apical perforation through the body of the root
Prognosis• Success of treatment depends primarily on the size and shape of the defect. An open apex or reverse funnel is difficult to seal and also allows extrusion of the filling materials.
Lateral (midroot) perforationsEtiology- There are two types of midroot perforations:a. Direct perforation as a result of pressure and force applied to a file during negotiation of ledged canals, or through post space preparation using cutting-end burb. Stripping perforation is a lateral perforation caused by overinstrumentation using files or drills like Gates-Glidden through a thin wall in the root and is most likely to happen on the inside (inner) wall of a curved canal, such as the distal (inner) wall of the mesial roots in mandibular first molars
Indicators- They are similar to those of apical perforation The area of hemorrhage on the point indicates the area where the strip has occurred.
PreventionTo avoid these perforations some factors should be considered:1. degree of canal curvature and size .2. inflexibility of the larger files, especially stainless steel files.
Treatment- The main goal is to instrument and obturate the entire root canal system- Perforation repair surgically or non-surgically using suitable restorative material (MTA) Repair of stripping perforation using MTA
Prognosis It depends on several factors: - Remaining amount of undebrided and unobturated canal. - Perforation size. - Surgical accessibility.• Obturation is difficult because of lack of a stop , and gutta-percha tends to be extruded during condensation.• Teeth with perforations close to the apex after complete or partial débridement of the canal have a better prognosis than those with perforations that occur earlier.• In addition to the length of uncleaned and unfilled portions of the canal, size and surgical accessibility of perforations are important.• In general, small perforations are easier to seal than large ones.
Coronal root perforationEtiology- Direct perforation happens during access preparation while the operator attempts to locate the canals- Stripping perforation happens during flaring procedures by files or Gates-GliddenPrevention- It is similar to what described earlier in the prevention of perforation during access preparation- Careful and conservative flaring, especially during using Gates-Glidden, is also recommended
Treatment & Prognosis• 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, even though the prognosis is guarded. Patency of the canal system must be maintained during the repair process. MTA is a promising material to repair almost all types of perforations
Etiology- Limited flexibility- Over use- Excessive forced applied to files- Improper use Notice: any instrument may break either steel, NiTi, hand or rotary
Recognition- Removal of shortened file from the canal- Loss of canal patency- Radiograph is essential for confirmation.
Prevention• limitations of files is critical.• Continual lubrication with either irrigating solution or lubricants is required.• Each instrument is examined before use ( flutes distortion).• Small files must be replaced often.• To minimize binding, each file size is worked in the canal until it is very loose before the next file size is used.• Nickel-titanium files usually do not show visual signs of fatigue similar to the “untwisting” of steel files, they should be discarded before visual signs of untwisting are seen .
Treatment- There are three approaches:1. Attempt to remove the instrument (using small file to bypass the instrument then retrieve it, using ultrasonic tips, or using especially designed pliers) Pliers
2- attempt to bypass it.3- prepare and obturate to the segment coronal to the instrument. The operator should attempt to bypass the separated instrument. After bypassing the separated instrument, ultrasonic files broaches, or Hedstrom files are used to remove the segment.If removal of the separated piece is unsuccessful, then the canal is cleaned, shaped, and obturated to its new working length.If the instrument cannot be bypassed, preparation and obturation should be performed to the coronal level of the fragment.
A, Arrow pointing to a separated instrument in the mesiolingual canalB, Postobturation film with an arrow identifying “tunneling” that was created with anultrasonic instrument to remove the separated instrument
Removal of broken instrument extended beyond the apex (arrow)
Prognosis It depends on how much undbrided and unobturated canal remains. The prognosis is best when separation of a large instrument occurs in the later stages of preparation close to the working length. Prognosis is poorer for teeth with undébrided canals in which a small instrument is separated short of the apex or beyond the apical foramen early in preparation. For medical-legal reasons, the patient must be informed of an instrument separation. If the patient remains symptomatic or there is a subsequent failure, the tooth can be treated surgically.
Instrument Aspiration orPrevention Ingestion- Rubber dam
Indicators- Instrument disappearance followed by severe coughing or gagging by the patient- RadiographTreatment- When the lost instrument is readily accessible, high volume suction, hemostat, or cotton pliers may help to retrieve the instrument. Otherwise, referral to a medical service is required and major surgical intervention may also be required
Swallowed endodontic file ended up in appendix and led to acute appendicitisand appendectomy. Rubber dam would have prevented this tragedy.
Extrusion of Irrigant• Wedging of a needle in the canal or out of a perforation with forceful expression of irrigant causes penetration of irrigants into the periradicular tissues and inflammation and discomfort for patients.• Loose placement of irrigation needles and careful irrigation with light pressure or use of a perforated needle precludes forcing the irrigating solution into the periradicular tissues.• Sudden prolonged and sharp pain during irrigation followed by rapid diffuse swelling (the “sodium hypochlorite accident”) usually indicates penetration of solution into the periradicular tissues.
Severe swelling caused by injecting hydrogen peroxide irrigant into tissues.
A BA, Hemorrhagic reaction caused by NaOCl accidentB, Healing within few weeks
Treatment- Because of the potential for spread of infection related to tissue destruction, it is advisable to prescribe antibiotics in addition to analgesics for pain- Antihistamines can also be helpful- Ice packs applied initially to the area, followed by warm saline soaks the following day, should be initiated to reduce the swelling- In more severe cases, hospitalization and surgical intervention with wound débridement, may be necessary- Patient reassurance
Prognosis- Generally is favorable- In some cases, the long-term effects of irrigant injection into the tissues have included paresthesia, scarring, and muscle weakness
UndefillingCauses- Natural barrier in the canal.- Ledge.- Insufficient flaring.- Poorly adapted master cone.
Prevention- Confirmatory MAC radiograph .- If displacement of the MAC is suspected, a radiograph is made before excess gutta-percha removal .Treatment- Re-treatment
OverfillingCauses- Overinstrumentation- Open apex- Uncontrolled condensation forces
Prevention- Avoid overinstrumentation.- Prepare apical matrix (seat).- Confirmatory MAC radiograph.- If displacement of the MAC is suspected, a radiograph is made before excess gutta-percha removal.- In case of wide (open) apex, a solvent customized cone technique is preferred .
Treatment- In case of endodontic failure, apical surgery may be required to remove the extruded materialPrognosis- It depends on some factors: quality of the apical seal, amount and biocompatibility of extruded material, and host response
Usually, slight over extension of GP cone beyond the apex(around 2 mm) doesn’t cause problem and doesn’t needfurther treatment.
Surgical removal of extended gutta-percha beyond the apex
Causes- Overflaring- Screw post placement- Post cementation- Excessive applied forces during gutta-percha condensationPrevention- Appropriate (conservative) canal preparation- Balanced applied forces during condensation- Finger spreaders produce less stress than hand fingers during obturation
Treatment- Removal of the fractured root in multi-rooted tooth and extraction of single-rooted tooth
Root PerforationPrevention- Gutta-percha removal using heated pluggers.- Good knowledge of root canal anatomy, location of the root, and its direction in the alveolus.- Gates-Glidden and Peeso reamer are safe, however, they can lead to excessive removal of tooth structure and therefore can potentially lead to “stripping” perforation or root fracture.- High speed burs shouldn’t be used at all in post space preparation
Indicators- Bleeding during preparation- Sinus tract or pocket extended to the post base- Lateral radiographic radiolucency radiographic radiolucency caused root perforation during post space preparation
Treatment- Non-surgical repair if the post can be removed (as stated in management of root perforation)- Surgical repair if the post cannot be removed and the perforation is accessible- Otherwise extraction is required
Non-surgical repair using MTA of perforation caused during post space preparation
Prognosis- It depends on: perforation size, surgical accessibility, and perforation location ( apical perforation has better prognosis than that close to the gingival sulcus)