Procedural errors in endodontics; aetiology, prevention and management. Dr. Ahmad El-Ma aita

Transcription

1 Procedural errors in endodontics; aetiology, prevention and management Year 5 DDS Nov Dr. Ahmad El-Ma aita BDS, MSc, PhD, MEndo RCSEd

2 Definition: Any mistake that occurs at some point during root canal treatment Access cavity-related: Treating the wrong tooth Missed canals Damage to existing restoration Crown fractures Access cavity perforations Errors during instrumentation: Ledge, zipping, canal transportation Perforations Separated instruments Canal blockage Obturation-related: Over- or under-extended obturation Nerve paresthesia Vertical root fractures Miscellaneous: Irrigant-related mishaps Tissue emphysema Instrument aspiration and ingestion

3 Treatment of the Wrong Tooth Aetiology: either misdiagnosis or inattention. Prevention: a) Ensure correct diagnosis through detailed history and examination. b) Mark the tooth which requires treatment (with a pen!). Management: a) Complete the treatment of both teeth b) Inform the patient

4 Missed canals: Most common canals to be missed: Mesio-palatal (MB2) of maxillary molars Canals in the distal roots of mandibular molars Second canals in lower incisors Second canals in lower premolars Third canals in upper pre-molars. Prevention: Prepare adequate access cavity Always expect there will be an extra canal. Use magnification (surgical microscope or loupes) Check angled radiographs (CBCT??)

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7 Damage to an existing restoration: Porcelain crowns are the most susceptible to chipping and fracture. Prevention: Use a water-cooled, smooth diamond bur Do not force the bur (let it cut its own way) Do not place a rubber dam clamp on the gingiva of a porcelain or porcelain-faced crown.

8 Crown fracture: Access cavities weaken the crown. Crown fractures can occur during preparation or between appointments. One of the frequent causes is failure to relieve the occlusion. Restorability needs to be checked before proceeding with the treatment.

9 Perforations: Definition: Pathologic or iatrogenic communication between the pulp space and the oral or peri-radicular tissues. Aetiology: A- Iatrogenic: 1- Misaligned use of burs during access preparation and search for canal orifices 2- During efforts to negotiate calcified and curved canals 3- Overzealous instrumentation towards a root concavity (Strip perforation) 4- Inappropriate post space preparation B- Pathological: 1- Caries 2- Root resorption

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15 Bacterial infection emanating either from the root canal or the periodontal tissues, or both, prevents healing and brings about inflammatory sequels. This results in pain, suppurations, abscesses, and fistulae. Down-growth of gingival epithelium to the perforation site can emerge, especially when accidental perforations occur in the crestal area by lateral perforation or perforation in furcations of multi-rooted teeth. Once an infectious process has established itself at the perforation site, prognosis for treatment is precarious and extraction may be needed.

16 Prognosis of perforations: Whether or not a root perforation can be successfully treated depends on whether the perforation can be repaired such that bacterial infection of the perforation site can either be prevented or eliminated Prognosis depends on: 1) Time 2) Size 3) Location 4) Adequacy of seal

17 Perforation Description Prognosis Fresh Treated immediately or shortly after occurrence under aseptic conditions Good Old Previously not treated with likely bacterial infection Questionable Small Large Coronal (smaller than #20 endodontic instrument) Minimal mechanical tissue damage with easy sealing opportunity Done during post preparation, with significant tissue damage and obvious difficulty in providing an adequate seal, salivary contamination, or coronal leakage along temporary restoration, Coronal to the level of crestal bone and epithelial attachment with minimal damage to the supporting tissues and easy access, Good Questionable Good Crestal At the level of the epithelial attachment into the crestal bone, Questionable Apical Apical to the crestal bone and the epithelial attachment, Good Fuss and Trope. Endod Dent Traumatol 1996: 12:

18 Detection and determination of location : Sudden bleeding and pain during instrumentation. The patient may complain of NaOCl taste. Angled radiographs taken with a radiopaque instrument in the suspected perforation. Electronic apex locators can accurately determine the location of root perforations. A dental operating microscope is another helpful tool A narrow isolated deep periodontal pocket is a possible sign of periodontal breakthrough due to root perforation (Vertical root fracture needs to be excluded).

19 Management: 1- Measures for prevention 2- Treatment by an orthograde approach: Regain access to the root canal space to complete disinfection Haemorrhage control Provision of adequate seal Materials used include: Amalgam IRM GIC MTA/ Biodentine

20 Management: 3- Treatment by a surgical approach To surgically expose the perforation site and achieve a fluid-tight seal. To prevent bacteria and their byproducts in the root canal from entering the surrounding periodontal tissues 4- Orthodontic extrusion?? (for crestal perforations) 5- Intentional replantation When orthograde and surgical treatments are not possible, undesirable, or have already failed

21 Yilmaz et al. J Endod 2010;36:160-3

22 Instrumentation-related errors: 1-Ledge II- Zip and transportation III-Perfortaion IV- Strip perforation

23 Instrumentation-related errors: 1-Ledge: When the tip of an inflexible instrument with a cutting tip gouges into the wall of a curved canal. Loss of the working length Smaller flexible instruments with non-cutting tips are pre-curved in order to regain access to the original canal.

24 Instrumentation-related errors: II- Zip and transportation Zipping is the result of the tendency of an instrument to straighten inside a curved root canal. This results in over-enlargement of the outer side of the curvature and under-preparation of the inner aspect at the apical end point. The main axis of the canal is transported. Therefore, the terms straightening, deviation, transportation and hour-glass shape are also used to describe this type of defect.

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26 Instrumentation-related errors: III- Apical perforations: May occur as a result of preparation with inflexible instruments with a sharp cutting tip Perforations are associated with destruction of the root cementum and irritation and/or infection of the periodontal ligament and are difficult to seal Part of the original root canal will remain un- or underprepared (compromised disinfection)

27 Instrumentation-related errors: IV- Strip perforation: Due to overzealous instrumentation towards the inner wall of a curved canal. Common in mesial roots of lower molars and ribbon-shaped premolars. Anti-curvature filing (M. Abou-Rass 1980)

28 Instrumentation-related errors: V- Apical blockage: Apical blockage of the root canal occurs as a result of packing of tissue or debris and results in loss of patency and working length. As a consequence complete disinfection of the most apical part of the root canal system is not possible Recapitulation and patency filing are important to prevent blockage

29 VI- Instrument separation: So what? 2 types of failure: cyclic and torsional. Factors to consider The pre-operative status of the tooth The presence of apical pathology The stage at which the file was separated At which part of the root Constraints of the canal (curvature, root thickness, cross section ) Type of instrument Clinician s expertise and armamentarium

30 VI- Instrument separation: Management options: 1) Retrieval 2) Bypass 3) Instrumentation and obturation to the # file level 4) Surgical options: (apicectomy, root amputation/ hemisection, intentional replantation) 5) Extraction

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36 How to reduce the incidence of instrument separation? 1- Pre-assessment of the case complexity II- Straight line access III- Copious irrigation IV- Preflaring the coronal canal V- Achieve a glide path VI- Single use of instruments VII- Working length radiograph VIII- Follow manufacturer s instructions IX- Anti-curvature filing X- Avoid apical pressure XI- Clean the flutes regularly XII- Patency filing?

37 Obturation-related mishaps: I- Over-extended root fillings: The apical termination point of canal instrumentation and obturtion is the apical constriction (dentinocemental junction) Slight extrusion of the root canal filling is called a puff or button. Healing against these slight overfills is usually inconsequential. Loss of apical constriction by perforation is often the cause of overextension when there is no barrier compact the root filling against. Gross overextension may deter healing and may even end up in the maxillary sinus or the mandibular canal. Nerve paresthesia is a possible result. For massive overfills, removal by surgery followed by a retrofilling is often the only solution

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39 II- Under-extended root fillings: Under/ over-extension vs short/ long root filling Pulpitis: vital apical pulp stump Non-vital: potential persistent source of irritation

40 Miscellaneous errors: I- Sodium hypochlorite accident: NaOCl is extremely caustic and tissue toxic. Forcibly injecting NaOCl into the peri-apical tissues can have disastrous consequences. The patient immediately complains of severe pain and swelling. This is followed by echymosis, paresthesia, tissue necrosis, scarring, and muscle weakness. Concentration is important! (0.5% vs. 6%) Early realization is key. It is not a chlorine allergy! But rather a dentist-induced error! Ending up in court may be the least of one s problems.

41 Sodium hypochlorite accident: Prevention: Passive placement of the irrigating needle (no wedging). Side-vented or notched needles are recommended. Prevention: No great force is exerted on the plunger of the syringe Passive placement of the irrigating needle (no wedging). (use index finger) Side-vented or notched needles are recommended. Use lower concentrations of sodium hypochlorite. No great force is exerted on the plunger of the syringe (use index finger Prevention: Strict working length control Passive placement of the irrigating needle (no wedging). Management: Side-vented or notched needles are recommended. Copious irrigation with saline or sterile water. No great force is exerted on the plunger of the syringe (use index finger Strong analgesics Antibiotics (??) Ice packs Antihistamines and intra-muscular steroids Hospitalization and surgical intervention may be needed.

42 II- Subcutaneous tissue emphysema: Collection of air (or another gas) below the subcutaneous tissues Relatively uncommon. Two actions may cause this to happen: A blast of air to dry a canal (more likely to happen with youngsters, in whom the canals in anterior teeth are relatively large) Exhaust air from a high-speed drill directed toward the tissue. The usual sequence of events is rapid swelling, erythema, and crepitus. It is usually a benign condition that resolves over 3 10 days as the gas is resorbed into the blood stream for eventual excretion via the lungs. Complications (although rare) include: pneumomediastinum, airway compromise and death! Rickls NH, Joshi BA. Death from air embolism during root canal therapy. J. Am. Dent. Assoc. 1963; 67:

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44 Subcutaneous tissue emphysema: Prevention: Use paper points. Do not blow air directly down an open canal. Employ a handpiece that exhausts the spent air out the back of the handpiece rather than into the operating field. Management: Reassurance Referral and hospitalization A course of antibiotics designed to cover normal oral flora (weak evidence)

45 III- Instrument aspiration and ingestion Swallowed endodontic instrument because a rubber dam was not used. The radiograph was taken 15 minutes after the broach was swallowed. Courtesy of B. Heling and I. Heling.

46 This radiograph shows the presence of an endodontic instrument among the intestinal loops. Few weeks later, the patient died!

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48 Instrument aspiration and ingestion Always use a rubber dam! If one insists on placing rubber dam clamps before the dam is placed, the clamp should be fitted with a long string of dental floss to aid in its recovery If instrument aspiration or ingestion is apparent, the patient must be taken immediately to a medical emergency facility for examination, and the dentist must accompany the patient. Radiography of the thorax and abdomen. (It is helpful if the dentist takes a sample file along so the radiologist has a better idea of what to look for) Surgical intervention would be the only solution. Be prepared for a session in court!!

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50 Appendix removed from a patient after an endodontic file ended up in the appendix. Courtesy of L.C. Thomsen and colleagues.

51 Thank you