Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Use and effectiveness of the Failure Modes and Effects Analysis (FMEA) for identification of potential errors and failures in the process of root canal treatment Mohsen Yazdanian1, Mostafa Alam2, Esmail Rafiee1,3, Elahe Tahmasebi1,*, Arash Ghaffarpasand2, Kamyar Abbasi4, Mohammadkarim Bahadori1 1Research Center for Prevention of Oral and Dental Diseases, Baqiyatallah University of Medical Sciences, Tehran, Iran. 2Department of Oral and Maxillofacial Surgery, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran 3School of Dentistry, Baqiyatallah University of Medical Sciences, Tehran, Iran. 4Department of Prosthodontics, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran Abstract Objec�ves: Root canal treatment (RCT) has high technical sensi�vity, and many human procedural errors can compromise the success of treatment and well-being of pa�ents. The failure modes and effects analysis (FMEA) is a risk assessment and management tool that ensures the safety of pa�ent care by a systema�c approach to failures. This study aimed to iden�fy the poten�al errors and failures in the process of RCT using the FMEA. Methods: This descrip�ve study evaluated the failure modes and their effects qualita�vely and quan�ta�vely using the FMEA methodology. For this purpose, a FMEA team was first established and the steps of RCT were described in a flowchart. Next, the poten�al errors and failures in each step were iden�fied, and each failure mode was scored from 1 to 10, based on the severity of impact, likelihood of occurrence, and likelihood of detec�on. The three scores were mul�plied to obtain the risk priority number (RPN). Correc�ve measures and preven�ve strategies were suggested for high-risk failure modes (RPN≥250). Results: The FMEA iden�fied 19 steps and 48 poten�al failures in the process of RCT. The maximum RPN in the process of RCT was assigned to file fracture in the root canal (RPN=324), apical extrusion of irriga�ng solu�on (RPN=320), and inappropriate or no rubber dam isola�on (RPN=315). Conclusion: The FMEA has high efficacy for detec�on and priori�za�on of improvable points in a complex dental procedure in a busy department such as the endodon�cs department. Keywords: Den�stry; Endodon�cs; Failure Modes and Effects Analysis; Risk Priority Number; Pa�ent Safety; Human Errors Cita�on: Yazdanian M, et al. (2022). Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment. Den�stry 3000. 1:a001 doi:10.5195/d3000.2022.238 Received: September, 13, 2021 Accepted: October 21, 2021 Published: August 12, 2022 Copyright: ©2022 Yazdanian M, et al. This is an open access ar�cle licensed under a Crea�ve Commons Atribu�on Work 4.0 United States License. Email: elahe.tahmasebi.delfan@gmail.com Introduction Patient safety is a fundamental healthcare principle, which refers to prevention of any harm to patients during provision of healthcare services [1]. In order to ensure patient safety, it is imperative to identify the events that threaten the patient’s health, analyze the process of occurrence of such events, and design and implement corrective strategies to improve the performance of the system [1]. The frequency of medical malpractice lawsuits, as a factor threatening the patient safety, has greatly increased in the recent years. According to the international reports, the frequency of medical malpractice lawsuits has been on the rise despite the great technological advances in diagnostic and http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu treatment procedures. For instance, the percentage of physicians who had been sued at least once in the United States was 3-4% in 1970, 8% in 1972, 20% in 1980, and 25% in 1990 [2]. The dental profession is no exception to this rule and dentists may also be held civilly liable for their practice. In a study the dentists were found guilty in 44.3% of the lawsuit cases researched. Endodontics was one of the most frequently involved specialty in the lawsuits analyzed, and was related to a high incidence of damages awarded to settle claims [3]. Among different dental specialties, endodontics includes various procedures with high technical sensitivity such as anesthesia, caries removal, working length determination, chemomechanical debridement of the root canal system, and root canal obturation. Inaccuracy and errors in any step of the procedures can compromise the patient’s health [4,5]. Although errors in provision of dental care are expected to have lower morbidity and mortality rates than the medical errors, their prevention can increase patient satisfaction, decrease costs, increase credibility, and lower the stress level of both patients and dental care providers. Part of the errors than may occur in dental practice are related to human errors while another part is related to environmental conditions, quality of dental instruments and equipment, and the dental office setting, that would eventually compromise patient safety [6]. Evidence shows that analysis of human errors prior to their occurrence can prevent them to a great extent [7]. Moreover, risk assessment and risk management are gaining increasing popularity in many professions and industries in order to prevent or minimize the occurrence of errors and to increase the credibility and efficiency of the system in the current competitive market [8]. Implementation of error management techniques is an effective approach for detection and minimization of errors. Error management is an organized continuous process for identification, assessment and decision making about the risks and opportunities in a system, which would affect achieving the goals. At present, a great emphasis has been placed on error management as a key factor for ultimate success in achieving the organizational goals [9]. Several methods are available for risk assessment and error management. Some of them analyze errors prospectively and some retrospectively. The failure modes and effects analysis (FMEA), which is a prospective technique, is among the most valid and reliable techniques for risk management and prevention of errors in the healthcare systems according to the National Center for Patient Safety of the United States [5,10]. This technique was first used in the space industry in 1960, and is a qualitative and inductive method, and an organized tool and a completely cognitive preventive measure that operates based on team work. It is used for definition, identification, assessment, prevention, and elimination or control of potential failure modes and effects in a system, process, project or service, before the final product or service is received by the customer or client [11]. The main property of this technique is its ability in prediction of important errors and offering solutions to prevent their occurrence [10]. Its modified form is exclusively used for the healthcare systems, and offers a prospective systematic approach for identification and prevention of errors prior to their occurrence in healthcare http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu organizations. The first application of this technique in the healthcare system dates back to 1990 when it was primarily applied for optimization of vital systems, production and development of medications, and prevention of pharmaceutical errors in the hospitals [12]. FMEA aims to promote safety by preventing the occurrence of identified errors in a system and minimizing the unwanted consequences. This preventive and prospective approach allows identification and elimination of potential problems in an organization before they could impact on the system, services, and customers/clients [13]. Moreover, application of FMEA in the healthcare systems establishes a systematic attitude to promote patient safety. Evidence shows that FMEA can decrease the clinical risks of patients and identify and prioritize the improvable points of a process under implementation [14, 15]. Considering the high risk of procedural errors in the endodontics departments and the adverse consequences of such errors, this study sought to identify and prioritize the potential errors and failures in the process of root canal treatment (RCT) by the FMEA and offer corrective and safety measures for provision of services at the endodontics departments [16,17]. Methods This descriptive study evaluated the failure modes and effects qualitatively and quantitatively using the FMEA methodology. The logic of this study was inductive, yielding practical results. The FMEA is a team-based, systematic and prospective approach to foresee and prevent problems that may arise in the production process or provision of services prior to their occurrence. Hypothesis and Inclusion Criteria This study questioned the possible high-risk errors and failure modes that can occur in the process of root canal treatment; the possibility of identifying and prioritizing risks and their causes, and the feasibility of suggesting and implementing preventive or corrective measures in each step. The study was conducted in the Endodontics Department of the School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran, and focused on one main high-risk procedure done in this department, i.e. root canal treatment, between the years of 2019 and 2020. Team Assembly The FMEA team members consisted of 7 individuals that were purposefully chosen to be part of a Focus Discussion Group (FDG) [5]. The team consisted of two endodontists, one assistant from the endodontics department, one head nurse from the department, one clinic supervisor, one infection control personnel, and one quality control personnel of the specialty clinic (Table 1). In addition, 23 non-FMEA specialized endodontists, were selected as outside examiners to help identifying high risk procedures. http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Table 1. Members of the FMEA team Order Organizational ranking Educational level Work experience 1 Head of the department Endodontist 7 years 2 Attending dental clinician Endodontist 8 years 3 Assistant BS of nursing 3 years 4 Head nurse MS of nursing 5 years 5 Quality control personnel BS of nursing 3 years 6 Clinic supervisor BS of nursing 2 years 7 Quality control personnel MS of healthcare service management 3 years BS: Bachelor’s degree; MS: Master’s degree Inter-examiner agreements The team agreed to identify all root canal treatment steps, errors and failures, as well as implementing opportunities for improvement and correctional changes. Team members were allocated adequate time and resources to allow the process to be successful. The team leader (head of the department), who was skilled in team building, played a vital role in facilitating the various steps in the FMEA process, controlling the progress of the analysis, as well as assisting the team in applying a structured approach when identifying error causes and outlining necessary actions [6]. Data Collection Data were collected through observation, questionnaires, and discussion group interviews by holding team sessions and meetings. The Eindhoven classification model (ECM) was used to find the root causes of errors. In the next step, the FMEA team members defined the RCT procedural steps in a flowchart using the Visio software (Flowchart 1). The FMEA team members then identified and listed the possible procedural errors which may occur in every step of the process of RCT by brain storming, followed by determining the possible impacts of each error, and recorded them in a FMEA worksheet. http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Flowchart 1. Procedural steps of RCT Root Canal Therapy Taking the chief complaint and its history Can the patient undergo RCT? Clinical examination including vitality tests, radiographic examination, diagnosis and treatment planning Taking medical history NoReferral YesMouthwash Anesthetic injection Has adequate depth of anesthesia been achieved? No Yes Rubber dam isolation Caries removal Access cavity preparationDetermination of primary working length by initial file Taking a periapical radiograph from initial file Filing and irrigation of root canal to master apical file Taking a periapical radiograph from master apical file Insertion of master apical gutta-percha cone Taking a periapical radiograph from master apical cone Root canal obturation with accessory cones and sealer Cutting the excess length of gutta-percha points Taking the final radiograph Temporary restoration of the tooth Referral to a restorative dentist or prosthodontist Does root canal orifice provide adequate access to the entire canal length? Yes NoWidening of orifice by Gates-Glidden drills Follow-up Prioritizing errors and assigning RPN In the FMEA, assessment of the sensitivity and significance of a risk is performed by assigning a numerical value to it, known as the risk priority number (RPN) [18]. Higher RPN of an error indicates higher risk for the system or its products [19]. Accordingly, the identified failure modes in the previous step were prioritized according to their RPN. The RPN is calculated by multiplying the scores assigned to the severity of impact (S), likelihood of occurrence (O), and likelihood of http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu detection (D), which can be scored from 1 to 10 (Figure 1). Accordingly, considering the range of 1 < RPN < 1000, errors/failures with RPN ≥ 250 were classified as high-risk errors and entered the next level [20] (Figures 2 and 3). After prioritizing the errors and calculation of their RPN, the root causes of high-risk errors were identified according to the ECM. In the ECM, the causes of errors are classified into two main categories of latent (technical and organizational errors) and apparent/active errors (human errors and other types). Figure 1. Severity ra�ng scale of failure modes Figure 3. Occurrence ra�ng scale of failure modes Figure 2. Detec�on ra�ng scale of failure modes Identifying causes of error modes Finally, according to the RPNs, possible failure or error causes were discussed and noted, and consequently, corrective and preventive measures were suggested for the high-risk failure modes. These measures, depending on the type of error/failure, focused on decreasing the severity of impact and rate of occurrence of errors/failures, and/or increasing the possibility of their detection. Data analysis The data was organized according to the FMEA principles and the process of RCT was defined step- by-step in a flowchart, and the failure modes and effects and their root causes were determined and listed in the FMEA worksheet. The procedures which had higher risks were prioritized using the http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Borda Function and the analyzed according to their Risk Priority Number (RPN). Ethical measures The patients’ privacy was preserved and their personal information was protected in all steps of the study. Informed consent was attained from all patients. Results Nineteen steps and 48 potential errors/failures were identified and recorded for the RCT. Next, according to the respective tables for S, O and D, the FMEA team members individually scored each potential failure mode in several sessions, and the RPN of each failure mode was determined according to a 1-10 scale by multiplying the scores of S, O and D, and taking into account the ange of 1 < RPN < 1000 (Table 2). In this study, RPN > 250 was considered high-risk and unacceptable in RCT [21]. Next, corrective measures were suggested for high-risk failure modes to prevent their occurrence, increase the likelihood of their detection, or decrease their impact in order to compile the details of process modification by focusing on the aforementioned three strategies. Totally, of the defined 19 steps and 48 identified errors, 12 errors were selected and categorized as high-risk, for which, corrective and preventive measures were suggested (Table 3). One potential error was found in the process of taking the chief complaint and history of patient. Three potential errors were identified in the process of taking a medical history; among which, not asking the patient about the history of systemic diseases acquired the highest score with RPN=63. Five errors were identified I the process of clinical examination, radiographic examination, diagnosis and treatment planning; among which, RCT of teeth with poor or hopeless periodontal prognosis was classified as a high- risk error (RPN=252). Six errors were identified in the process in anesthetic injection; among which, injection of unsafe doses of anesthetic agents containing vasoconstrictor in patients with contraindication (RPN=159), and injection of anesthetic agent in excessive amounts (RPN=158) acquired the maximum scores. Two errors were identified in the process of isolation; among which, inappropriate or no rubber dam isolation (RPN=315) was classified as a high-risk error. Six potential errors were identified in the process of removal of caries and previous restorations; among which, no reduction of unsupported cusps (RPN=275) was classified as a high-risk error. Three errors were identified in the process of access cavity preparation; among which, not finding additional root canals (RPN=271) was classified as a high- risk error. In the process of widening the root canal orifice, careless use of Gates-Glidden drills (RPN=288) was classified as a high- risk error. One error was identified in the process of primary working length determination by the initial file, and three errors were identified in the process of taking periapical radiograph from the initial file; among which, incorrect determination of root canal working length (RPN=211) acquired the highest score. http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Table 2. Primary FMEA worksheet for RCT Process steps Modes of errors Type of error Impact of errors Causes of errors RPN Taking patient complaint and history Incorrect understanding of patient complaint and descriptions Human, systematic Treating the wrong tooth, incorrect treatment plan Not allocating sufficient time by the dentist, crowded clinic, poor verbal communication with patient, poor sympathy with patient 56 Taking medical history Not asking the patient about important systemic diseases Human, systematic Occurrence of cardiovascular or other systemic problems Not allocating sufficient time by the dentist, crowded clinic, not adhering to the protocol regarding filling out the health questionnaire prior to the onset of treatment, shortage of human resources 63 Not asking female patients whether they are pregnant Human, systematic Injury to the fetus Inaccuracy of dentist, not adhering to the protocol regarding filling out the health questionnaire prior to the onset of treatment, shortage of human resources, no option regarding choosing a female dentist for female patients 56 Not asking patients about their allergy history Human, systematic Risk of occurrence of allergic reactions in susceptible patients Not allocating sufficient time by the dentist, crowded clinic, inaccuracy of dentist, not adhering to the protocol regarding filling out the health questionnaire prior to the onset of treatment, shortage of human resources 35 Clinical and radiographic examination, diagnosis and treatment planning Diagnosis and treatment planning merely based on radiographic examination Human Treating the wrong tooth, incorrect treatment plan Not allocating sufficient time by the dentist, inaccuracy of dentist 65 Not requesting appropriate radiography Human Incorrect treatment plan Inaccuracy of dentist, poor education and inexperience of dentist 56 Excess request of radiography Human Excessive X-ray exposure, increased risk of cancer Poor education and inexperience of dentist 36 Root canal treatment of a tooth with poor or hopeless periodontal prognosis Human, systematic Progression of periodontal disease, mobility, necessitating later extraction Not asking for periodontal consultation prior to RCT for periodontally compromised or suspected teeth 252 RCT of complex root canals by a general dentist Human, systematic Abscess after RCT and treatment failure Absence of an organizational treatment protocol 278 Local anesthesia administration Injection of anesthetic agent containing vasoconstrictor in Human Development of cardiovascular complications Not taking precise medical history, inaccuracy of dentist, poor education and inexperience of dentist 159 http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu excessive amounts in a patient with contraindications Not performing aspiration prior to anesthetic injection Human Entry of anesthetic agent into the bloodstream and subsequent development of cardiovascular problems, signs and symptoms of overdose Not allocating sufficient time by the dentist, inaccuracy of dentist, poor education and inexperience of dentist 69 Multiple insertions of needle into a highly vascularized area Human Rupture of vessel wall and development of hematoma Inaccuracy of dentist, poor education and inexperience of dentist 93 Excessive injection of anesthetic agent without taking into account the patient’s weight Human Systemic toxicity (overdose) Inaccuracy of dentist, poor education and inexperience of dentist 158 Sudden change in direction of movement of needle in the tissue, precurving the needle in several points Human Fracture of needle in the tissue Inaccuracy of dentist, poor education and inexperience of dentist 69 Induction of long-term anesthesia for a short-duration procedure Human Development of traumatic ulcer due to soft tissue biting Inaccuracy of dentist, poor education and inexperience of dentist 59 Isolation of the respective tooth Improper or no rubber dam isolation Human, systematic Aspiration of dental instruments into the respiratory tract, traumatization of soft tissue or adjacent teeth, saliva leakage into the root canal, abscess formation Inaccuracy of dentist, poor education and inexperience of dentist, absence of a clear treatment protocol 315 Use of latex rubber dam in a patient allergic to latex Human, systematic Allergy in susceptible patients Not asking the patient about history of allergy, inaccuracy of dentist, not adhering to the protocol regarding filling out the health questionnaire prior to the onset of treatment, shortage of medical equipment and instruments 211 Removal of caries and previous restoration Carelessness in correct use of bur Human, systematic Traumatization of mucocutaneous surfaces or traumatizing the adjacent teeth with bur Inaccuracy of dentist, inexperience of dentist, use of burs without protective guards 222 http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu No irrigation during caries removal Systematic Thermal damage to enamel and dentin Malfunction of medical equipment 196 Application of uncontrolled force during caries removal, or excessive removal of tooth structure Human Irreparability of tooth crown, weakening of tooth structure and increased risk of tooth fracture Inexperience of dentist 111 Incomplete elimination of caries Human Development of secondary caries, requiring endodontic retreatment Inaccuracy of dentist, inexperience of dentist 96 Not reducing unsupported cusps Human Tooth fracture Inexperience of dentist 275 Not using face mask when removing old amalgam restoration with high- speed hand-piece Human Mercury vapor toxicity, increased risk of cancer Inexperience of dentist 218 Access cavity preparation Excessive removal of tooth structure Human Inability to ideally restore the crown, weakening of tooth structure, increased risk of fracture, tooth perforation Inexperience of dentist 86 Creating an undersized access cavity Human No straight path to the root canals Inexperience of dentist 87 Not finding additional root canals in molar teeth, particularly the second mesiobuccal canal in the maxillary molars and mid-mesial canal in the mandibular molars and mandibular lateral incisors Human, systematic Development of abscess after RCT, treatment failure RCT of complicated cases by a general dentist, absence of an organizational treatment protocol 271 Orifice flaring if required Careless use of Gates-Glidden drills Human Fracture of Gates-Glidden drills in the root canal, vertical root fracture Poor education and inexperience of dentist 288 Primary working length determination by initial file Incorrect working length determination Human, systematic Over-filling or under-filling Inexperience of dentist, shortage of materials and equipment 211 http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Periapical radiography of initial file Incorrect film positioning Human Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist 59 Under-exposure or over-exposure of the film Human Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist 68 Inappropriate film processing Human, systematic Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist, shortage of materials and equipment 67 Filing and root canal irrigation to master apical file, followed by further filing and root canal debridement Leakage of root canal irrigating solutions into the oral cavity Human Mucosal burning, liquid aspiration into the respiratory tract Inexperience of dentist 211 Inadequate filing and irrigation of root canal system Human Failure of RCT in long-term Not allocating sufficient time by the dentist, inexperience of dentist 236 File fracture in the root canal Human, systematic Abscess formation and failure of RCT in long-term Inaccuracy of dentist, inexperience of dentist, multiple use of thin files, shortage of materials and equipment 324 Apical extrusion of irrigating solution Human, systematic Hypochlorite accident Inexperience of dentist, use of high-concentration hypochlorite, apical extrusion of irrigating solution 320 Root canal transportation Human Apical perforation Inexperience of dentist 170 Ledge formation Human Perforation of external root surface Inexperience of dentist 159 Ignoring the danger zone Human Strip perforation Poor education and inexperience of dentist 245 Packing of debris in the root canal and obstruction of the main canal path Human Not accessing the entire working length and under- filling Inexperience of dentist 244 Changing the working length Human Over-filling or under-filling, failure of RCT in long-term Inexperience of dentist 226 http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Periapical radiography of master apical file Improper film positioning Human Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist 59 Under-exposure or over-exposure of film Human Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist 68 Inappropriate film processing Human, systematic Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist, shortage of dental materials and equipment 67 Placement of master apical gutta-percha cone Selection of an undersized master apical cone Human Apical extrusion of gutta- percha, inappropriate apical seal, over-filling, failure of RCT in long-term Poor education and inexperience of dentist 89 Selection of an oversized master apical cone Human Under-filling of root canal, treatment failure in long-term Poor education and inexperience of dentist 77 Periapical radiography of master apical cone Inappropriate film positioning Human Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist 59 Under-exposure or over-exposure of film Human Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist 68 Inappropriate film processing Human, systematic Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist, shortage of dental materials and equipment 67 Root canal obturation by insertion of accessory gutta-percha cones and sealer Apical extrusion of sealer or accessory gutta-percha cones Human Infection, inflammatory reaction Inexperience of dentist 236 Application of excessive force by the spreader Human Vertical root fracture Inexperience of dentist 288 Root canal filling with inadequate density (void formation) Human Failure of RCT in long-term Not allocating sufficient time by the dentist, inexperience of dentist 208 Cutting excess gutta- percha Contact of hot endodontic plugger with the skin or mucosa Human, systematic Burning of skin and mucosa Inaccuracy of dentist, inexperience of dentist, shortage of dental materials and equipment 265 http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Falling of the torch Human, systematic Fire Inaccuracy of dentist, inexperience of dentist, unavailability of electronic devices for cutting of excess gutta-percha, shortage of dental materials and equipment 241 Final periapical radiography Improper film positioning Human Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist 59 Under-exposure or over-exposure of film Human Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist 68 Inappropriate film processing Human, systematic Repeating radiography, over- exposure of patient, increased risk of cancer Inexperience of dentist, shortage of dental materials and equipment 67 Temporary restoration Carrying the filling material with the wrong instrument Human, systematic Contamination of filling material, waste of material Inexperience of dentist, shortage of dental materials and equipment 56 Over-filling of the access cavity with temporary restoration Human Temporomandibular disorders Not allocating sufficient time by the dentist, inexperience of dentist, 69 Poor retention of temporary restoration Human Early loss of temporary restoration, requiring replacement or necessitating endodontic retreatment Inexperience of dentist 48 Referral to a restorative dentist or prosthodontist for final restoration Not showing up for final restoration at an appropriate time Human, systematic Requiring endodontic retreatment, abscess formation Negligence by patient, negligence by assistant, absence of an organizational protocol 252 http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Table 3. Suggested measures for high-risk errors in the process of RCT High-risk failure modes RPN Suggested measures Root canal treatment of a tooth with poor or hopeless periodontal prognosis 252 - Designing an organizational treatment protocol necessitating written periodontal consultation prior to RCT for periodontally compromised or suspected teeth - Holding continuing education courses for dental clinicians Inappropriate or no rubber dam isolation 315 - Designing an organizational treatment protocol necessitating rubber dam isolation for RCT - Use of files with thread holes (at least for patients with poor cooperation) No reduction of unsupported cusps 275 - Designing an organizational treatment protocol necessitating cusp reduction, and reduction of unsupported walls to prevent tooth fracture (depending on the tooth) - Holding continuing education courses for dental clinicians Not finding additional root canals especially the second mesiobuccal canal in maxillary molars and mid- mesial canals in mandibular molars and mandibular lateral incisors 271 - Designing an organizational treatment protocol necessitating treatment of complex root canals exclusively by endodontists Careless use of Gates-Glidden drills 288 - Holding continuing education courses for dental clinicians File fracture in the root canal 324 - Holding continuing education courses for dental clinicians - Provision of high-quality files in the endodontics departments - Not using thin files for multiple teeth Apical extrusion of irrigating solutions 320 - Holding continuing education courses for dental clinicians - Designing an organizational treatment protocol necessitating precise determination of the safe concentration of sodium hypochlorite for use in endodontics departments Excessive force application by the spreader 288 - Holding continuing education courses for dental clinicians - Educating dental clinicians regarding controlled force application in use of spreader Contact of hot plugger with the skin or mucosa 265 - Holding continuing education courses for dental clinicians - Use of rubber dam until the completion of RCT to protect the skin and mucosa Not showing up in-time for final restoration of the tooth 252 - Raising awareness and informing the patients about the problems that may occur in case of not showing up for final restoration in-time, or nursing and following the patient by the assistant http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu A total of 12 errors were identified in the process of taking a periapical radiograph from the master apical file, and continuation of filing and debridement of the root canal; among which, file fracture in the root canal (RPN=324) and apical extrusion of irrigating solutions (RPN=320) were classified as high- risk errors. A total of 8 errors were identified in the process of insertion of master apical cone, taking a periapical radiograph from it, and filling the rest of the root canal with accessory gutta- percha points and sealer; among which, excessive force application by the spreader resulting in a bend or deformation, or breakage of the spreader (RPN=288) was considered as a high-risk error. A total of 8 errors were identified in the process of cutting the excess end of gutta-percha points, taking the final radiograph, and temporary restoration of the tooth; among which, contact of hot endodontic plugger with the skin or mucosa (RPN=365) was classified as a high-risk error. In the process of patient referral to a restorative dentist or prosthodontist for final restoration of the tooth, not showing up in-time for final restoration (RPN=252) was classified as a high-risk error. Discussion In the recent years, many studies have focused on the human errors in high-risk dental fields due to their significant impact on health, costs, and quality of life of patients [7,22]. In this study, the FMEA was employed to identify errors related to RCT in the endodontics departments. Accordingly, the potential impacts and causes of errors were determined by the team members, and corrective strategies were suggested for high-risk errors. According to the results of this study, file fracture in the root canal, apical extrusion of irrigating solutions, and inappropriate or no rubber dam isolation, acquired the maximum RPNs, and were classified as errors with maximum risk in the process of RCT. Tzanetakis et al. [23] reported the prevalence of file fracture to be 1.83% and discussed that its occurrence had an inverse correlation with the experience level of dental clinicians, such that it had the highest frequency among dental students and lowest frequency among endodontists [23]. According to some studies, file fracture does not decrease the RCT prognosis [24,25]. However, some others believe that file fracture increases the risk of RCT failure [26,27]. McGuigan et al, [28] in their review study concluded that although file fracture does not increase the rate of endodontic treatment failure in cases without periapical disease, risk of endodontic failure increases following file fracture in teeth with a preexisting periapical lesion. Thus, they recommended attempts to remove the broken piece from the root canal. Strategies suggested by the FMEA team in our study to minimize the occurrence of file fracture and decrease its RPN included continuing education courses for dental clinicians, and provision of high-quality files for the endodontics departments, as well as control over the number of usage of instruments. These strategies have been confirmed by a previous study as well [23]. For instance, evidence shows that higher education and training and greater experience decrease the occurrence of file fracture [23,28]. Also, McGuigan et al, [28] in their review study reported that type of alloy used by the manufacturer in the composition of files affects the frequency of file fracture, and use of high-quality files can minimize the occurrence of this adverse event [28]. Hypochlorite accident is among the oldest complications of RCT [29]. Rowland et al. [30] performed a literature review on this topic and concluded that its prevalence is highly variable. Leakage of sodium hypochlorite into the periapical tissues can cause hemolysis, prevent the migration of neutrophils, and damage the endothelial cells and fibroblasts [31]. The toxic effects of sodium hypochlorite are due to http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu its alkaline nature and hypertonicity, which can cause oxidation of proteins and lipid membranes [31]. Patients often experience excruciating pain, and their clinical examination reveals ecchymosis, hematoma, swelling, and temporary paresthesia (with a lower prevalence rate) [32]. Pain and swelling may last for 1-4 months [33,34], and healing of injured mucosa may take up to 2 months [35]. Also, hypochlorite accident can even cause irreversible complications such as fibrosis and unesthetic scarring [36,37]. Obviously, educating dental clinicians regarding the use of other irrigating solutions such as saline or chlorhexidine, or use of diluted sodium hypochlorite, and delivary of irrigating solutions only in the root canal environment, by use of 30 G needles either with open-ended or side-vented cannulas, while moving inside the root canal with a plunger force of 10–40 N, can decrease the occurrence of hypochlorite accident [19,29,47]. Futhermore, the hypochlorite accident may be due to operator malpractice or negligence. Over 140 years have passed since the introduction of rubber dam as an effective isolation tool in dentistry [38]. During this time period, its application has been technically simplified, and it is widely used by dental clinicians in restorative dentistry, endodontics, periodontics and pedodontics [39]. According to Madarati et al, [18] use of rubber dam alone can serve as an independent factor in prevention of many dental complications, particularly in endodontics [18]. However, evidence shows that still a lot of dental clinicians do not routinely use rubber dam isolation in RCT due to a number of reasons such as poor compliance and acceptance by patients, time required for its installation, related costs, and not receiving adequate instruction about its use and its difficult installation [40]. Not using rubber dam can cause cross-contamination, prevent ideal irrigation of root canal, adversely affect the treatment results, and increase the risk of swallowing or aspiration of dental materials and instruments [41]. Thus, use of rubber dam is imperative as a standard of care, and is an integral part of the organizational treatment protocols in many universities and dental clinics worldwide [42-45]. In addition, during the coronavirus disease (COVID-19) outbreak, as aerosols and airborne particles can easily be generated during endodontic treatment, the use of personal protective barriers and rubber dam is recommended at the dental office [48]. The current results well indicated that a large portion of root causes of the most important potential errors in the process of RCT are due to inexperience, poor education, and lack of scientific knowledge of dental clinicians. Ghasemi et al. [46] reported that the majority of errors performed by post-graduate students of endodontics were procedural errors due to their inexperience, inadequate skills, outdated scientific information, imbalance between the number of patients and attending endodontists, and inefficacy and inadequacy of the protocols and guidelines. Accordingly, they suggested the inclusion of a separate course on human errors as part of dental curricula. The FMEA identifies and prioritizes the potential errors in a prospective manner. Retrospective review of studies regarding the common procedural errors in the process of RCT revealed that the potential risks classified as high-risk by FMEA were all among the commonly reported, important, and challenging errors in the field of endodontics. This finding highlights the factuality and efficacy of FMEA and further confirms its credibility for accurate detection of errors and risks in the process of RCT. It appears that adherence to the corrective and preventive measures in a logical time period can decrease the risk of such errors in the respective organizations/institutions. Clearly, after the termination of this time period, re-implementation of FMEA in the respective organizations/institutions and calculation of RPN of the potential errors can reveal the efficacy of corrective and preventive measures and indicate the quality of their implementation [29]. http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Conclusion According to the current results, identification of potential errors in the process of RCT, detection of high-risk (unacceptable) errors, finding their root causes, and offering corrective measures to prevent their occurrence all indicated the high efficacy of FMEA for identification, assessment, prioritization, and analysis of errors in endodontics departments. Moreover, combining group interviews with FMEA, identifying the framework of errors, designing comprehensive tables for the severity of impact, rate of occurrence, and rate of detection of errors, and finding the root causes of high-risk errors by using the RCA in this study decreased the effects of some limitations of the FMEA such as its time consuming nature and high dependence of the results on team participation of individuals, and consequently increased its efficacy. However, the efficacy of this approach in implementation of corrective measures was not tested in this study, and requires an implementation time period and further studies in this respect. Conflicts of interest The authors declare no competing interest. References 1. Verklan MT, Walden M, Forest S. Core curriculum for neonatal intensive care nursing e- book: Elsevier Health Sciences; 2020 . .2 Yamalik N, Perea Pérez B. Patient safety and dentistry: what do we need to know? Fundamentals of patient safety, the safety culture and implementation of patient safety measures in dental practice. International dental journal. 2012;62(4):189-96. PMID: 23017000. .3 Zanin AA, Herrera LM, Melani RF. Civil liability: characterization of the demand for lawsuits against dentists. Braz Oral Res. 2016 Aug 18;30(1). PMID: 27556556. .4 Thusu S, Panesar S, Bedi R. Patient safety in dentistry - state of play as revealed by a national database of errors. Br Dent J. 2012 Aug;213(3):E3. PMID: 22878337. .5 Wetterneck TB, Skibinski KA, Roberts TL, et al. Using failure mode and effects analysis to plan implementation of smart i.v. pump technology. Am J Health Syst Pharm 2006;63(16):1528–1538. PMID: 16896081. .6 Bailey E, Tickle M, Campbell S. Patient safety in primary care dentistry: where are we now? British dental journal. 2014;217(7):339-44. PMID: 25303580. .7 Chiozza ML, Ponzetti C. FMEA: a model for reducing medical errors. Clinica chimica acta. 2009;404(1):75-8. PMID: 19298799. .8 de Wet C, O’Donnell C, Bowie P. Developing a preliminary ‘never event’list for general practice using consensus-building methods. Br J Gen Pract. 2014;64(620):e159-e67. PMID: 24567655. .9 van Galen LS, Struik PW, Driesen BE, Merten H, Ludikhuize J, van der Spoel JI, et al. Delayed recognition of deterioration of patients in general wards is mostly caused by human related monitoring failures: a root cause analysis of unplanned ICU admissions. PloS one. 2016;11 .(8). PMID: 27537689. .10 Mikulak RJ, McDermott R, Beauregard M. The basics of FMEA: CRC Press; 2017 . .11 Ramoni RB, Walji MF, White J, Stewart D, Vaderhobli R, Simmons D ,et al. From good to better: toward a patient safety initiative in dentistry. The Journal of the American Dental Association. 2012;143(9):956-60. PMID: 22942131. .12 Pemberton M. Developing patient safety in dentistry. British http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu dental journal. 2014;217(7):335-7. PMID: 25303579. .13 Black I, Bowie P. Patient safety in dentistry: development of a candidate'never event'list for primary care. British Dental Journal. 2017;222(10):782-8. PMID: 28546608. .14 Brunton P. Summary of: Patient safety in dentistry–state of play as revealed by a national database of errors. British dental journal. 2012;213(3):126-7. PMID: 22878313. .15 Renton T, Sabbah W. Review of never and serious events related to dentistry 2005– 2014. British dental journal. 2016;221(2):71-9. PMID: 27444598. .16 Kalenderian E, Walji MF, Tavares A, Ramoni RB. An adverse event trigger tool in dentistry: a new methodology for measuring harm in the dental office. The Journal of the American Dental Association. 2013;144(7):808-14. PMID: 23813262. .17 Walji MF, Yansane A, Hebballi NB, Ibarra-Noriega AM, Kookal KK, Tungare S, Kent K, McPharlin R, Delattre V, Obadan- Udoh E, Tokede O, White J, Kalenderian E. Finding Dental Harm to Patients through Electronic Health Record-Based Triggers. JDR Clin Trans Res. 2020 Jul;5(3):271-277. PMID: 31821766. .18 Madarati AA. Why dentists don’t use rubber dam during endodontics and how to promote its usage? BMC oral health. 2016;16(1):24. PMID: 26916426. .19 Parashos P, Messer HH. Rotary NiTi instrument fracture and its consequences. J Endod. 2006 Nov;32(11):1031-43. PMID: 17055902. .20 Kalenderian E, Obadan- Udoh E, Yansane A, Kent K, Hebballi NB, Delattre V, et al. Feasibility of electronic health record–based triggers in detecting dental adverse events. Applied clinical informatics. 2018;9(3):646. PMID: 30134473. .21 Tanalp J, Güngör T. Apical extrusion of debris: a literature review of an inherent occurrence during root canal treatment. Int Endod J. 2014 Mar;47(3):211-21. PMID: 23711187. .22 Nahmias Y, Serota KS, Watson Jr W. Predictable Endodontic Success: Part II- Microstructural Replication. Oral Health. 2003;93(12):36-41. PMID: 12442825. .23 Tzanetakis GN, Kontakiotis EG, Maurikou DV, Marzelou MP. Prevalence and management of instrument fracture in the postgraduate endodontic program at the Dental School of Athens: a five-year retrospective clinical study. Journal of Endodontics. 2008;34(6):675-8. PMID: 18498887. .24 Friedman S. Expected outcomes in the prevention and treatment of apical periodontitis . Essential endodontology: prevention and treatment of apical periodontitis. 2008:408-69. PMID: 21689541 .25 Spili P, Parashos P, Messer HH. The impact of instrument fracture on outcome of endodontic treatment. J Endod. 2005;31(12):845-50. PMID: 16306815. .26 Kerekes K, Tronstad L. Long-term results of endodontic treatment performed with a standardized technique. J Endod. 1979 Mar;5(3):83-90. PMID: 296248. .27 Strindberg LZ. The dependence of the results of pulp therapy on certain factors-an analytical study based on radiographic and clinical follow-up examination. Acta Odontol Scand. 1956;14:1-175. PMID: 2084204. .28 McGuigan M, Louca C, Duncan H. The impact of fractured endodontic instruments on treatment outcome. British dental journal. 2013;214(6):285-9. PMID: 23518972. .29 Guivarc'h M, Ordioni U, Ahmed HM, Cohen S, Catherine JH, Bukiet F. Sodium Hypochlorite Accident: A Systematic Review. J http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu Endod. 2017 Jan;43(1):16-24. PMID: 27986099. .30 Hatton J, Walsh S, Wilson A. Management of the sodium hypochlorite accident: a rare but significant complication of root canal treatment. BMJ Case Rep. 2015 Mar 25;2015:bcr2014207480. PMID: 25809429. .31 Gernhardt CR, Eppendorf K, Kozlowski A, Brandt M. Toxicity of concentrated sodium hypochlorite used as an endodontic irrigant. Int Endod J. 2004 Apr;37(4):272-80. PMID: 15056354. .32 de Sermeño RF, da Silva LA, Herrera H, Herrera H, Silva RA, Leonardo MR. Tissue damage after sodium hypochlorite extrusion during root canal treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009 Jul;108(1):e46- 9. PMID: 19442541. .33 Markose G, Cotter CJ, Hislop WS. Facial atrophy following accidental subcutaneous extrusion of sodium hypochlorite. British Dental Journal. 2009;206(5):263-4. PMID: 19287421. .34 Pelka M, Petschelt A. Permanent mimic musculature and nerve damage caused by sodium hypochlorite: a case report. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology ,and Endodontology. 2008;106(3):e80-e3. PMID: 18602848. .35 Mehra P, Clancy C, Wu J. Formation of a facial hematoma during endodontic therapy. J Am Dent Assoc. 2000 Jan;131(1):67- 71. PMID: 10649874. .36 Chaudhry H, Wildan TM, Popat S, Anand R, Dhariwal D. Before you reach for the bleach. British Dental Journal. 2011;210(4):157-60. PMID: 21350524. .37 Al-Sebaei MO, Halabi OA, El-Hakim IE. Sodium hypochlorite accident resulting in life- threatening airway obstruction during root canal treatment: a case report. Clin Cosmet Investig Dent. 2015 Mar 4;7:41-4. PMID: 25767406. .38 Elderton R. A modern approach to the use of rubber dam--1. The Dental practitioner and dental record. 1971;21(6):187. PMID: 5278933. .39 Palmer NO, Ahmed M, Grieveson B. An investigation of current endodontic practice and training needs in primary care in the north west of England. Br Dent J. 2009 Jun 13;206(11):E22; discussion 584-5. PMID: 19478812. .40 Hill EE, Rubel BS. Do dental educators need to improve their approach to teaching rubber dam use? J Dent Educ. 2008 Oct;72(10):1177-81. PMID: 18923098. .41 Ahmad I. Rubber dam usage for endodontic treatment: a review. International endodontic journal. 2009;42(11):963-72. PMID: 19825034. .42 Kim SG, Malek M, Sigurdsson A, Lin LM, Kahler B. Regenerative endodontics: a comprehensive review. Int Endod J. 2018 Dec;51(12):1367-1388. PMID: 29777616. .43 European Society of Endodontology. Quality guidelines for endodontic treatment: consensus report of the European Society of Endodontology. Int Endod J. 2006 Dec;39(12):921-30. PMID: 17180780. .44 Gilbert GH, Litaker MS, Pihlstrom DJ, Amundson CW, Gordan VV; DPBRN Collaborative Group. Rubber dam use during routine operative dentistry procedures: findings from the Dental PBRN. Oper Dent. 2010 Sep-Oct;35(5):491-9. PMID: 20945739. .45 American Academy on Pediatric Dentistry Clinical Affairs Committee-Pulp Therapy subcommittee; American Academy on Pediatric Dentistry Council on Clinical Affairs. Guideline on pulp therapy for primary and young permanent http://dentistry3000.pitt.edu/ Use and effec�veness of the Failure Modes and Effects Analysis (FMEA) for iden�fica�on of poten�al errors and failures in the process of root canal treatment Vol 10 No 1 (2022) DOI 10.5195/d3000.2022.238 htp://den�stry3000.pit.edu teeth. Pediatr Dent. 2008- 2009;30(7 Suppl):170-4. PMID: 19216417. .46 Ghasemi M, Khoshakhlagh AH, Mahmudi S, Fesharaki MG. Identification and assessment of medical errors in the triage area of an educational hospital using the SHERPA technique in Iran. Int J Occup Saf Ergon. 2015;21(3):382- 90. PMID: 26327157. .47 Jäggi M, Magni E, Eggmann F, ElAyouti A, Connert T, Weiger R. Apical Pressure Generated Using Conventional Syringe Irrigation in Immature Teeth—An In Vitro Study. Materials. 2021; 14(10):2580. PMID: 34063549 .48 Silva WO, Vianna Silva Macedo RP, Nevares G, Val Rodrigues RC, Grossi Heleno JF, Braga Pintor AV, Almeida BM. Recommendations for Managing Endodontic Emergencies during Coronavirus Disease 2019 Outbreak. J Endod. 2021 Jan;47(1):3-10. PMID: 33045270. http://dentistry3000.pitt.edu/ References .1 Verklan MT, Walden M, Forest S. Core curriculum for neonatal intensive care nursing e-book: Elsevier Health Sciences; 2020. 2. Yamalik N, Perea Pérez B. Patient safety and dentistry: what do we need to know? Fundamentals of patient safety, the safety culture and implementation of patient safety measures in dental practice. International dental journal. 2012;62(4):189-96. P... 3. Zanin AA, Herrera LM, Melani RF. Civil liability: characterization of the demand for lawsuits against dentists. Braz Oral Res. 2016 Aug 18;30(1). PMID: 27556556. 4. Thusu S, Panesar S, Bedi R. Patient safety in dentistry - state of play as revealed by a national database of errors. Br Dent J. 2012 Aug;213(3):E3. PMID: 22878337. .5 Wetterneck TB, Skibinski KA, Roberts TL, et al. Using failure mode and effects analysis to plan implementation of smart i.v. pump technology. Am J Health Syst Pharm 2006;63(16):1528–1538. PMID: 16896081. 6. Bailey E, Tickle M, Campbell S. Patient safety in primary care dentistry: where are we now? British dental journal. 2014;217(7):339-44. PMID: 25303580. 7. Chiozza ML, Ponzetti C. FMEA: a model for reducing medical errors. Clinica chimica acta. 2009;404(1):75-8. PMID: 19298799. 8. de Wet C, O’Donnell C, Bowie P. Developing a preliminary ‘never event’list for general practice using consensus-building methods. Br J Gen Pract. 2014;64(620):e159-e67. PMID: 24567655. 9. van Galen LS, Struik PW, Driesen BE, Merten H, Ludikhuize J, van der Spoel JI, et al. Delayed recognition of deterioration of patients in general wards is mostly caused by human related monitoring failures: a root cause analysis of unplanned ICU ad... 10. Mikulak RJ, McDermott R, Beauregard M. The basics of FMEA: CRC Press; 2017. 11. Ramoni RB, Walji MF, White J, Stewart D, Vaderhobli R, Simmons D, et al. From good to better: toward a patient safety initiative in dentistry. The Journal of the American Dental Association. 2012;143(9):956-60. PMID: 22942131. 12. Pemberton M. Developing patient safety in dentistry. British dental journal. 2014;217(7):335-7. PMID: 25303579. 13. Black I, Bowie P. Patient safety in dentistry: development of a candidate'never event'list for primary care. British Dental Journal. 2017;222(10):782-8. PMID: 28546608. 14. Brunton P. Summary of: Patient safety in dentistry–state of play as revealed by a national database of errors. British dental journal. 2012;213(3):126-7. PMID: 22878313. 15. Renton T, Sabbah W. Review of never and serious events related to dentistry 2005–2014. British dental journal. 2016;221(2):71-9. PMID: 27444598. 16. Kalenderian E, Walji MF, Tavares A, Ramoni RB. An adverse event trigger tool in dentistry: a new methodology for measuring harm in the dental office. The Journal of the American Dental Association. 2013;144(7):808-14. PMID: 23813262. 17. Walji MF, Yansane A, Hebballi NB, Ibarra-Noriega AM, Kookal KK, Tungare S, Kent K, McPharlin R, Delattre V, Obadan-Udoh E, Tokede O, White J, Kalenderian E. Finding Dental Harm to Patients through Electronic Health Record-Based Triggers. JDR Clin ... 18. Madarati AA. Why dentists don’t use rubber dam during endodontics and how to promote its usage? BMC oral health. 2016;16(1):24. PMID: 26916426. 19. Parashos P, Messer HH. Rotary NiTi instrument fracture and its consequences. J Endod. 2006 Nov;32(11):1031-43. PMID: 17055902. 20. Kalenderian E, Obadan-Udoh E, Yansane A, Kent K, Hebballi NB, Delattre V, et al. Feasibility of electronic health record–based triggers in detecting dental adverse events. Applied clinical informatics. 2018;9(3):646. PMID: 30134473. 21. Tanalp J, Güngör T. Apical extrusion of debris: a literature review of an inherent occurrence during root canal treatment. Int Endod J. 2014 Mar;47(3):211-21. PMID: 23711187. 22. Nahmias Y, Serota KS, Watson Jr W. Predictable Endodontic Success: Part II-Microstructural Replication. Oral Health. 2003;93(12):36-41. PMID: 12442825. 23. Tzanetakis GN, Kontakiotis EG, Maurikou DV, Marzelou MP. Prevalence and management of instrument fracture in the postgraduate endodontic program at the Dental School of Athens: a five-year retrospective clinical study. Journal of Endodontics. 2008... 24. Friedman S. Expected outcomes in the prevention and treatment of apical periodontitis. Essential endodontology: prevention and treatment of apical periodontitis. 2008:408-69. PMID: 21689541 25. Spili P, Parashos P, Messer HH. The impact of instrument fracture on outcome of endodontic treatment. J Endod. 2005;31(12):845-50. PMID: 16306815. 26. Kerekes K, Tronstad L. Long-term results of endodontic treatment performed with a standardized technique. J Endod. 1979 Mar;5(3):83-90. PMID: 296248. 27. Strindberg LZ. The dependence of the results of pulp therapy on certain factors-an analytical study based on radiographic and clinical follow-up examination. Acta Odontol Scand. 1956;14:1-175. PMID: 2084204. 28. McGuigan M, Louca C, Duncan H. The impact of fractured endodontic instruments on treatment outcome. British dental journal. 2013;214(6):285-9. PMID: 23518972. 29. Guivarc'h M, Ordioni U, Ahmed HM, Cohen S, Catherine JH, Bukiet F. Sodium Hypochlorite Accident: A Systematic Review. J Endod. 2017 Jan;43(1):16-24. PMID: 27986099. 30. Hatton J, Walsh S, Wilson A. Management of the sodium hypochlorite accident: a rare but significant complication of root canal treatment. BMJ Case Rep. 2015 Mar 25;2015:bcr2014207480. PMID: 25809429. 31. Gernhardt CR, Eppendorf K, Kozlowski A, Brandt M. Toxicity of concentrated sodium hypochlorite used as an endodontic irrigant. Int Endod J. 2004 Apr;37(4):272-80. PMID: 15056354. 32. de Sermeño RF, da Silva LA, Herrera H, Herrera H, Silva RA, Leonardo MR. Tissue damage after sodium hypochlorite extrusion during root canal treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009 Jul;108(1):e46-9. PMID: 19442541. 33. Markose G, Cotter CJ, Hislop WS. Facial atrophy following accidental subcutaneous extrusion of sodium hypochlorite. British Dental Journal. 2009;206(5):263-4. PMID: 19287421. 34. Pelka M, Petschelt A. Permanent mimic musculature and nerve damage caused by sodium hypochlorite: a case report. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology. 2008;106(3):e80-e3. PMID: 18602848. 35. Mehra P, Clancy C, Wu J. Formation of a facial hematoma during endodontic therapy. J Am Dent Assoc. 2000 Jan;131(1):67-71. PMID: 10649874. 36. Chaudhry H, Wildan TM, Popat S, Anand R, Dhariwal D. Before you reach for the bleach. British Dental Journal. 2011;210(4):157-60. PMID: 21350524. 37. Al-Sebaei MO, Halabi OA, El-Hakim IE. Sodium hypochlorite accident resulting in life-threatening airway obstruction during root canal treatment: a case report. Clin Cosmet Investig Dent. 2015 Mar 4;7:41-4. PMID: 25767406. 38. Elderton R. A modern approach to the use of rubber dam--1. The Dental practitioner and dental record. 1971;21(6):187. PMID: 5278933. 39. Palmer NO, Ahmed M, Grieveson B. An investigation of current endodontic practice and training needs in primary care in the north west of England. Br Dent J. 2009 Jun 13;206(11):E22; discussion 584-5. PMID: 19478812. 40. Hill EE, Rubel BS. Do dental educators need to improve their approach to teaching rubber dam use? J Dent Educ. 2008 Oct;72(10):1177-81. PMID: 18923098. 41. Ahmad I. Rubber dam usage for endodontic treatment: a review. International endodontic journal. 2009;42(11):963-72. PMID: 19825034. 42. Kim SG, Malek M, Sigurdsson A, Lin LM, Kahler B. Regenerative endodontics: a comprehensive review. Int Endod J. 2018 Dec;51(12):1367-1388. PMID: 29777616. 43. European Society of Endodontology. Quality guidelines for endodontic treatment: consensus report of the European Society of Endodontology. Int Endod J. 2006 Dec;39(12):921-30. PMID: 17180780. 44. Gilbert GH, Litaker MS, Pihlstrom DJ, Amundson CW, Gordan VV; DPBRN Collaborative Group. Rubber dam use during routine operative dentistry procedures: findings from the Dental PBRN. Oper Dent. 2010 Sep-Oct;35(5):491-9. PMID: 20945739. 45. American Academy on Pediatric Dentistry Clinical Affairs Committee-Pulp Therapy subcommittee; American Academy on Pediatric Dentistry Council on Clinical Affairs. Guideline on pulp therapy for primary and young permanent teeth. Pediatr Dent. 2008-... 46. Ghasemi M, Khoshakhlagh AH, Mahmudi S, Fesharaki MG. Identification and assessment of medical errors in the triage area of an educational hospital using the SHERPA technique in Iran. Int J Occup Saf Ergon. 2015;21(3):382-90. PMID: 26327157. .47 Jäggi M, Magni E, Eggmann F, ElAyouti A, Connert T, Weiger R. Apical Pressure Generated Using Conventional Syringe Irrigation in Immature Teeth—An In Vitro Study. Materials. 2021; 14(10):2580. PMID: 34063549 .48 Silva WO, Vianna Silva Macedo RP, Nevares G, Val Rodrigues RC, Grossi Heleno JF, Braga Pintor AV, Almeida BM. Recommendations for Managing Endodontic Emergencies during Coronavirus Disease 2019 Outbreak. J Endod. 2021 Jan;47(1):3-10. PMID: 33...