Procedural Accidents (Endodontics Mishaps ) Dr. MunaMarashdeh MSc. Endodontics
Lecture Outline • DEFINITION • CLASSIFICATION • ACCIDENTS DURING ACCESS PREPARATION • ACCIDENTS DURING CLEANING AND SHAPING • ACCIDENTS DURING OBTURATION • ACCIDENTS DURING POST SPACE PREPARATION
DEFINITION • Endodontic mishaps or procedural accidents are those unfortunate accidents that happen during treatment, some owing to inattention to detail, others being totally unpredictable
CLASSIFICATION • ACCIDENTS DURING ACCESS PREPARATION • ACCIDENTS DURING CLEANING AND SHAPING • ACCIDENTS DURING OBTURATION • ACCIDENTS DURING POST SPACE PREPARATION
ACCIDENTS DURING ACCESS PREPARATION Proper access opening is key to ensure an errorless procedure during cleaning and shaping, if not gained it would be beginning of procedural failure. Main errors during access opening are • Access Cavity Perforations • Treatment of the Wrong Tooth • Missed Canals • Damage to an Existing Restoration
Access Cavity Perforations • 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.
Causes • Despite anatomic variations in the configuration of various teeth, the pulp chamber, in most cases, is located in the center of the anatomic crown. • The pulp system is located in the long axis of the tooth. • Lack of attention to the degree of axial inclination of a tooth in relation to adjacent teeth and to alveolar bone may result in either gouging or perforation of the crown or the root at various levels . • Failure to check the orientation of the access opening during preparation may result in a perforation. The dentist should stop periodically to review the bur-tooth relationship
misdirected bur created severe gouging and near-perforation during an otherwise routine access cavity preparation
Prevention • Clinical Examination • Thorough knowledge of tooth morphology, including both surface and internal anatomy and their relationships, is mandatory to prevent pulp chamber perforations. • Next, location and angulation of the tooth must be related to adjacent teeth and alveolar bone to avoid a misaligned access preparation. • In addition, radiographs of teeth from different angles provide information about the size and extent of the pulp chamber and the presence of internal changes such as calcification or resorption.
Operative Procedures • Initiating access without a rubber dam is preferred, because it allows better crown-root alignment. • Failure to recognize when the bur passes through the roof of the pulp chamber if the chamber is calcified may result in gouging or perforation of the furcation. • After penetration of the roof of the chamber, using a “safe-ended” access bur, will prevent perforation of the chamber floor
The use of apex locators and angled radiographs is necessary for early perforation detection. Early detection reduces damage caused by continued treatment (irrigation, cleaning and shaping) and improves the prognosis for nonsurgical repair. • Use appropriate light source during access preparation • Using magnifying glasses or an operative microscope will also aid in locating small orifices
Recognition and Treatment • Perforations must be recognized early to avoid subsequent damage to the periodontal tissues with intracanal instruments and irrigants. • Early signs of perforation may include one or more of the following: • sudden pain during the working length determination • sudden appearance of hemorrhage • burning pain or a bad taste during irrigation with sodium hypochlorite; • other signs, including a radiographicallymalpositioned file or a PDL reading from an apex locator that is far short of the working length.
Unusually severe postoperative pain may result from cleaning and shaping procedures performed through an undetected perforation. • When a perforation occurs or is strongly suspected, the patient should be considered for referral to an endodontist. • After long-term evaluation, other procedures, such as surgery, may be necessary if future failure occurs.
Lateral Root Perforation • The location and size of the perforation during access are important factors in a lateral perforation. If the defect is located at or above the height of crestal bone, the prognosis for perforation repair is favorable. • These defects can be easily and repaired with standard restorative material such as amalgam, glass ionomer, or composite. • Teeth with perforations below the crestal bone in the coronal third of the root generally have the poorest prognosis. • Attachment often recedes and a periodontal pocket forms, with attachment loss extending apically to at least the depth of the defect.
The treatment goal is to position the apical portion of the defect above crestal bone. • Orthodontic root extrusion is generally the procedure of choice for teeth in the esthetic zone • Crown lengthening may be considered when the esthetic result will not be compromised or when adjacent teeth require surgical periodontal therapy. • Internal repair of these perforations by mineral trioxide aggregate (MTA) has been shown to provide an excellent seal as compared to other materials
Furcation Perforation • A perforation of the furcation is generally one of two types: the “direct” or the “stripping” type. • Each is created and managed differently and the prognoses vary. • The direct perforation usually occurs during a search for a canal orifice. It is more of a “punched-out” defect into the furcation with a bur and is usually accessible, may be small, and may have walls. • This type of perforation should be immediately (if possible) repaired with MTA . • Prognosis is usually good if the defect is sealed immediately.
A stripping perforation involves the furcation side of the coronal root surface and results from excessive flaring with files or drills. • stripping perforations are generally inaccessible, requiring more elaborate approaches. • Long-term failure results from leakage of the repair material, which produces periodontal breakdown with attachment loss. • Skillful use of MTA has significantly improved the prognosis of nonsurgical repair of stripping perforations compared with other repair materials.
Nonsurgical Treatment • If feasible, nonsurgical repair of furcation perforations is preferred over surgical intervention. • Traditionally, materials, such as amalgam, gutta-percha, zinc oxide–eugenol, Cavit, calcium hydroxide have been used clinically and experimentally to seal these defects. • Repair is difficult because of potential problems with visibility, hemorrhage control, and management and sealing ability of the repair materials. • In general, perforations occurring during access preparation should be sealed immediately, but the patency of the canals must be protected. Immediate repair of the perforations with MTA offers the best results for perforation repair.
Surgical Treatment • Surgery requires more complex restorative procedures and more demanding oral hygiene from the patient. • Surgical alternatives are hemisection, bicuspidization, root amputation, and intentional replantation. • The remaining roots are prone to caries, periodontal disease, and vertical root fracture. • Treatment planning options, including extraction, should be discussed with the patient when the prognosis is poor
Prognosis • Factors affecting the long-term prognosis of teeth after perforation repair include the location of the defect in relation to crestalbone, the length of the root trunk, the accessibility for repair, the size of the defect( less than 1 mm), the presence or absence of a periodontal communication to the defect, the time lapse between perforation and repair, the sealing ability of restorative material, and subjective factors such as the technical competence of the dentist and 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 and bifurcated canals in lower premolars, as well as third canals in upper premolars are also missed. • One must be prepare adequate occlusal access
ACCIDENTS DURING CLEANING AND SHAPING • The most common procedural accidents during cleaning and shaping of the root canal system are ledge formation, artificial canal creation, root perforation, instrument separation, and extrusion of irrigating solution periapically. • Correction of these accidents is usually difficult, and the patient should be referred to an endodontist.
Ledge Formation • By definition, a ledge has been created when the working length can no longer be negotiated and the original patency of the canal is lost. • The major causes of ledge formation include • (1) inadequate straight-line access into the canal, • (2) inadequate irrigation or lubrication, • (3) excessive enlargement of a curved canal with files, and • (4) packing debris in the apical portion of the canal.
Prevention of a Ledge • The canals most prone to ledging are small, curved, and long • Procedures • Straight line access • An accurate working length measurement • Frequent recapitulation and irrigation • lubrication • A one-eighth to one-fourth reaming motion • A filing motion directed away from the furcation is used to form the funnel shape of the canal an reduce the coronal curvature. • Each file must be worked until it is loose before a larger size is used.
Management of a 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. • A “picking” motion is used to attempt to feel the catch of the original canal space, which is slightly short of the apical extent of the ledge. • 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
Prognosis • Failure of root canal treatment associated with ledging 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 the cleaning and shaping process. • 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.
Creating an Artificial Canal • Cause and Prevention • Deviation from the original pathway of the root canal system and creation of an artificial canal • A ledge is created and the proper working length is lost. • The operator, eager to regain that length, thus creating an artificial canal. • Used persistently, the file eventually perforates the root surface. • Aggressive use of steel files is the most common cause of this problem. • Management • Negotiating the original canal is very difficult. Rarely can the original canal be located, renegotiated, and prepared. • To obturate, the dentist should determine whether a perforation exists. • If there is no perforation, the canal is obturated with a warm or softened gutta-percha technique • If there is a perforation, the defect should be repaired • surgically .
Prognosis • Prognosis depends on the ability of the operator to renegotiate the original canal and the remaining uninstrumentedand unfilled portion of the main canal. • Unless a perforation exists, teeth in which the original canal can be renegotiated and obturatedhave a prognosis similar to those without procedure complications. • In contrast, when a large portion of the main canal is uninstrumented and unobturated, a poorer prognosis exists, and the tooth must be examined periodically. • Failure usually means surgery will be required to resect the uninstrumented and unobturated root canal
Root Perforations • Roots may be perforated at different levels during cleaning and shaping. • Location (apical, middle, or cervical) of the perforation and the stage of treatment affect prognosis. • Apical Perforations • Apical perforations occur through the apical foramen (overinstrumentation) or through the body of the root (perforated new canal). • Etiology and Indicators • Instrumentation of the canal beyond the apical constriction causes “zipping” or “blowing out” of the apical foramen. • The appearance of fresh hemorrhage in the canal, pain during canal preparation in a previously asymptomatic tooth, and sudden loss of the apical stop are indicators of foramen perforation
Prevention • To prevent apical perforation, proper working lengths must be established and maintained throughout the procedure • Treatment • Treatment includes establishing a new working length, creating an apical seat (taper), and obturating the canal to its new length. • Placement of MTA as an apical barrier can prevent extrusion of obturation materials. • 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) Perforations • Etiology and Indicators • Negotiation of ledged canals is not always possible, and misdirected pressure and force applied to a file may result in formation of an artificial canal and eventually in an apical or midroot perforation. • To avoid these perforations some factors should be considered: (1) degree of canal curvature and size and (2) inflexibility of the larger files, especially stainless steel files. • Indicators of lateral perforation are similar to those of apical perforation (i.e., fresh hemorrhage in the root canal or sudden pain and deviation of instruments from their original course).
Treatment • The optimal goal is to clean, shape, and obturate the entire root canal system of the affected tooth. After the perforation is confirmed • If attempts to negotiate the apical portion of the canal are unsuccessful, the operator should concentrate on cleaning, shaping, and obturating the coronal segment of the canal. • A new working length confined to the root is established, and the canal is then cleaned, shaped, and obturatedto the new working length. • A low concentration (0.5%) of sodium hypochlorite or saline should be used for irrigation in a perforated canal. Extrusion of concentrated irrigant into the surrounding periodontal tissues would produce sever inflammation
Prognosis • Success depends partially on the remaining amount of undébrided and unobturated canal. • Obturationis 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 Perforations • Etiology • Coronal root perforations occur during access preparation as the operator attempts to locate canal orifices or during flaring procedures with files, or Gates-Glidden drills. • Treatment and 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.
Separated Instruments • Etiology • Limited flexibility and strength of intracanal instruments combined with improper use may result in an intracanalinstrument separation. • Overuse or excessive force applied to files is the main cause of separation • Recognition • Removal of a shortened file with a blunt tip from a canal and subsequent loss of patency to the original length are the main clues for the presence of a separated instrument. • A radiograph is essential for confirmation.
Prevention • Recognition of the physical properties and stress 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 basically three approaches: • (1) attempt to remove the instrument, • (2) attempt to bypass it, or • (3) prepare and obturateto 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.
Prognosis • Prognosis depends on how much undébrided and unobturated canal apical to and including the instrument 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.
Extrusion of Irrigant • Wedging of a needle in the canal or out of a perforation with forceful expression of irrigantcauses 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 periradiculartissues. • 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. • There is no reason to prescribe antibiotics or attempt surgical drainage. • Analgesics are prescribed, and the patient is reassured. • Hospitalization and surgical intervention may be needed • Because the outcome is so dramatic, evaluation is performed frequently to follow progress.
Aspiration or Ingestion • Aspiration or ingestion of instruments is a serious event but is easily avoided with proper precautions. • Use of the rubber dam is the standard of care to prevent such ingestion or aspiration. • In the alimentary tract or airway • These patients require immediate referral to a medical service for appropriate diagnosis and treatment. • Surgical removal is required for some swallowed and nearly all aspirated instruments
Tissue Emphysema • Relatively uncommon • Two actions may cause this to happen: a blast of air to dry a canal, and exhaust air from a high-speed drill directed toward the tissue and not evacuated to the rear of the handpiece during apical surgery. • Emphysema from a blast of air down the canal is more likely to happen with youngsters, in whom the canals in anterior teeth are relatively large. • The usual sequence of events is rapid swelling, erythema, and crepitus. • Although the problem should not be treated lightly, the majority of reported cases have followed a benign course to total recovery. • Prevention is simple: use paper points. Do not blow air directly • down an open canal, and employ a handpiece that exhausts the spent air out the back of the handpiece rather than into the operating field.
ACCIDENTS DURING OBTURATION • Appropriate cleaning and shaping are the keys to preventing obturation problems because these accidents usually result from improper canal preparation. • In general, adequately prepared canals are obturated without mishap. The quality of obturation reflects canal preparation. However, problems do occur.
Underfilling • Etiology • Some causes of underfilling include a natural barrier in the canal, a ledge created during preparation, insufficient flaring, a poorly adapted master cone, and inadequate condensation pressure. • Treatment • Removal of underfilled gutta-percha and retreatment is preferred. • If lateral condensation is the method of obturation, the master cone should be marked to indicate the working length.
Overfilling • Extruded obturation material causes tissue damage and inflammation. • Postoperative discomfort (mastication sensitivity) usually lasts for a few days. • Etiology • Overfilling is usually the consequence of overinstrumentation • When the apex is open naturally or its constriction is removed during cleaning and shaping, there is no matrix against which to condense; • Other causes include inflammatory resorptionand incomplete development of the root
Prevention • To avoid overfilling, guidelines for preventing apical foramen perforation should be followed. • Tapered preparation with an apical “matrix” usually prevents overfill. • The largest file and master cone at working length should have a positive stop. • A customized master cone may be fabricated by briefly applying solvent on the tip. • Treatment and Prognosis • When signs or symptoms of endodontic failure appear, apical surgery may be required to remove the material from apical tissues and place root-end filling material. • Long-term prognosis is dictated by the quality of the apical seal, the amount and biocompatibility of extruded material, host response, and toxicity and sealing ability of the root-end filling material.
Vertical Root Fracture • Etiology • Causative factors include root canal treatment procedures and associated factors such as post placement. The main cause of vertical root fracture is post cementation, and the second in importance is excessive application of condensation forces to obturatean underprepared or overpreparedcanal. • Prevention • As related to root canal treatment procedures, the best means of preventing vertical root fractures are appropriate canal preparation and use of balanced pressure during obturation. A major reason for flaring canals is to provide space for condensation instruments. Finger spreaders produce less stress and distortion of the root than their hand counterparts. • Indicators • Long-standing vertical root fractures are often associated with a narrow periodontal pocket or sinus tract stoma, as well as a lateral radiolucency extending to the apical portion of the vertical fracture. • To confirm the diagnosis, a vertical fracture must be visualized. Exploratory surgery or removal of the restoration is usually necessary to visualize this mishap.
ACCIDENTS DURING POST SPACE PREPARATION • To prevent root perforation, gutta-percha may be removed to the desired level with heated pluggers or electronic heating devices • Attempting to remove gutta-percha with a drill only can result in perforation. • When a canal is prepared to receive a post, drills should be used sequentially, starting with a size that fits passively to the desired level. • preparation may result in perforation at any level. • indicators • Appearance of fresh blood during post space preparation is an indication for the presence of a root perforation. • The presence of a sinus tract stoma or probing defects extending to the base of a post is often a sign of root fracture or perforation. • Radiographs often show a lateral radiolucency along the root or perforation site.
Treatment and Prognosis • the prognosis of teeth with root perforation during post space preparation depends on the root size, location relative to epithelial attachment, and accessibility for repair. • Management of the post perforation generally is surgical if the post cannot be removed. If the post can be removed, nonsurgical repair is preferred . • Teeth with small root perforations that are located in the apical region and are accessible for surgical repair have a better prognosis than those that have large perforations, are close to the gingival sulcus, or are inaccessible.