Consideraciones para la atención de tratamientos endodóncicos en el contexto de la pandemia de COVID-19 / Considerations for the care of endodontic treatments in the context of the COVID-19 pandemic

La enfermedad COVID-19 fue declarada pandemia por la Organización Mundial de la Salud el 11 de marzo de 2020. El síndrome respiratorio agudo severo coronavirus-2 (SARS-CoV-2) es un virus transmitido de animales a seres humanos, altamente contagioso, cuyo periodo de incubación es de uno a 14 días. Los momentos por los que atraviesan la mayoría de los países debido a la pandemia declarada del COVID-19 han llevado a la proclamación de órdenes gubernamentales y/o recomendaciones en relación a la atención dental que debe dispensarse. En el momento actual, no se dispone de protocolos específicos oficiales, ni nacionales ni internacionales, que aborden de manera clara cómo debe proceder el odontólogo en su práctica diaria en la etapa posterior al confinamiento para trabajar con las mejores garantías de protección para los pacientes y el equipo humano de la consulta odontológica. Este estudio tuvo como objetivo analizar consideraciones para la atención de tratamientos endodóncicos en el contexto de la pandemia de COVID-19. Para lograr este objetivo se realizó una revisión bibliográfica en diferentes bases de datos, como: Google Scholar, Springer Link, Scopus, PubMed, para ello se emplearon estrategias de búsqueda, utilizando descriptores como: «endodontic¼, «recomendations¼, «odontology¼, «COVID-19¼, «pandemic¼ y operadores booleanos, con la finalidad de obtener información relevante y precisa. Contribuyendo a la práctica de la endodoncia con un protocolo general para el manejo de emergencias que muestre el fundamento del diagnóstico, los procedimientos clínicos y el uso de equipos de protección personal y barreras en el consultorio odontológico durante el brote de COVID-19 (AU)

The COVID-19 disease was declared a pandemic by the World Health Organization on March 11, 2020. The severe acute respiratory syndrome coronavirus (SARS-CoV-2) is a virus transmitted from animals to humans, highly contagious, whose incubation period is one to 14 days. The times that most countries are going through due to the declared COVID-19 pandemic have led to the proclamation of government orders and/or recommendations regarding the dental care that should be provided. At the present time, there are no specific official national or international protocols that clearly address how the dentist should proceed, in their daily practice, in the post-confinement stage, to work with the best guarantees of protection for the patients and the human team of the dental practice. The objective of this study was to analyze considerations for the care of endodontic treatments in the context of the COVID-19 pandemic. To achieve this objective, a bibliographic review was carried out in different databases, such as: Google Scholar, Springer Link, Scopus, PubMed, for this, search strategies were used, using descriptors such as: «endodontic¼, «recommendations¼, «odontology¼, «COVID-19¼, «pandemic¼ and Boolean operators, in order to obtain relevant and accurate information. Contributing to the practice of endodontics a general protocol for emergency management that shows the rationale for diagnosis, clinical procedures and the use of personal protective equipment and barriers in the dental office during the COVID-19 outbreak (AU)

Radiographic assessment of the relationship between root canal treatment quality, coronal restoration quality, and periapical status.

OBJECTIVE: The aim of this cross-sectional study was to assess the prevalence of apical periodontitis in root canal treated teeth in Turkish subpopulation and to evaluate the effects of both coronal restoration quality and root canal treatment (RCT) quality on apical periodontitis. MATERIALS AND METHODS: Panoramic images of individuals who applied to our department for different diagnostic reasons were randomly and retrospectively scanned. Total RCT number, RCT quality, type of coronal restoration, restoration quality, periapical status, and total number of teeth were recorded. The criteria used for coronal restorations quality and RCT quality were defined by De Moor et al. and slightly modified by Gunduz et al. Periapical status was assessed by the periapical index developed by Orstavik et al. Pearson's Chi-square test was used for statistical analysis, and the intraobserver agreements were assessed by Kappa coefficients. Values of P < 0.05 were accepted to be meaningful. RESULTS: The total examined teeth number was 6064, of which had 541 (8.9%) RCT. The prevelance of apical periodontitis was 40.5%. The number of adequate RCT was 178 (32.9%), and 138 (77.5%) of them were healthy. The number of adequate coronal restoration was 334, and 62.3% of them were healthy. For the cases that have adequate coronal restorations, there was statistically significant relationship between adequate RCT and periapical status (P < 0.001). CONCLUSION: The prevelance of apical periodontitis was 40.5% and there was statistically significant relationship between adequate RCT and periapical status.

[Scavenging strategy for root canal infection].

Root canal therapy is generally considered to be the most effective way to remove inflammation and infection in the root canal. However, the presence of persistent infection in the root canal may lead to a failure of the treatment. Therefore, the complete removal of root canal infection is essential for the success of root canal therapy. The purpose of root canal therapy is to clear up the intra-canal infection and thoroughly sterilize the root canal, and then fill up the root canal system with dimensionally, so as to prevent reinfection. This article focuses on the main methods and problems of the current root canal infection and the strategy of eradicating the infection in the root canal.

Evaluation of Quality and Preparation Time of Retrograde Cavities in Root Canals Filled with GuttaCore and Cold Lateral Condensation Technique.

INTRODUCTION: The aim of this study was to measure the time consumed preparing retrograde cavities in root canals of maxillary molars filled using the GuttaCore (Dentsply Tulsa Dental Specialties, Tulsa, OK) technique and the cold lateral condensation technique (CLC) and to examine the quality of the root-end cavity preparation by ultrasonic tips using micro-computed tomographic (micro-CT) scanning. METHODS: A total of 24 maxillary molars were included; distobuccal and palatal canals were instrumented to size #40 and size #50, respectively. Teeth were randomly distributed into 2 experimental groups; half of the samples were filled with CLC, and half were filled with the GuttaCore technique. After 2 months, the apical 3 mm of each root apex was resected. A retrograde cavity was then prepared 3 mm deep into the root-end-filled canals using ultrasonic tips. The quality of the preparation was first confirmed by a surgical stereomicroscope, and the time required for the root-end preparation was recorded. After root-end cavity preparation, all samples were scanned by micro-CT scanning. RESULTS: There was no significant difference between the palatal and distobuccal canals in the time required to prepare a retrograde cavity. Less time was required in the GuttaCore group to remove all root filling material and finish the cavity preparation than in the CLC group (P < .05), especially in the palatal canals. Micro-CT results confirmed that all material was removed from the root-end cavities and the absence of microcracks. CONCLUSIONS: GuttaCore was removed in less time from root-end cavities than root filling performed with the CLC technique. No damage to the surrounding dentin was detected by micro-CT scanning in the 2 groups.

Technical quality of root canal treatment performed by undergraduate students using hand instrumentation: a meta-analysis.

The technical quality of root canal treatment (RCT) may impact on the outcome. The quality of education received during undergraduate school may be linked to the quality of treatment provided in general dental practice. In this context, the aim of this systematic review was to answer the following focused questions: (i) What is the frequency of acceptable technical quality of root fillings, assessed radiographically, performed by undergraduate students? (ii) What are the most common errors assessed radiographically and reported in these treatments? For this purpose, articles that evaluated the quality of root fillings performed by undergraduate students were selected. Data were collected based on predetermined criteria. The key features from the included studies were extracted. GRADE-tool assessed the quality of the evidence. MAStARI evaluated the methodological quality, and a meta-analysis on all studies was conducted. At the end of the screening, 24 articles were identified. Overall frequency of acceptable technical quality of root fillings was 48%. From this total, 52% related to anterior teeth, 49% to premolars and 26% to molars. The main procedural errors reported were ledge formation, furcation perforation, apical transportation and apical perforation. The heterogeneity amongst the studies was high (84-99%). Five studies had a high risk of bias, eight had a moderate risk, and 11 had low risk. The overall quality of evidence identified was very low. The conclusion was that technical quality of root fillings performed by undergraduate students is low, which may reveal that endodontic education has limited achievement at undergraduate level. A plan to improve the quality of root fillings, and by extrapolation the overall quality of root canal treatment, should be discussed by the staff responsible for endodontic education and training.

Clinical audit training improves undergraduates' performance in root canal therapy.

AIM: To evaluate the effectiveness of clinical audit-feedback cycle as an educational tool in improving the technical quality of root canal therapy (RCT) and compliance with record keeping performed by dental undergraduates. METHODS: Clinical audit learning was introduced in Year 3 of a 5-year curriculum for dental undergraduates. During classroom activities, students were briefed on clinical audit, selected their audit topics in groups of 5 or 6 students, and prepared and presented their audit protocols. One chosen topic was RCT, in which 3 different cohorts of Year 3 students conducted retrospective audits of patients' records in 2012, 2014 and 2015 for their compliance with recommended record keeping criteria and their performance in RCT. Students were trained by and calibrated against an endodontist (κ ≥ 0.8). After each audit, the findings were reported in class, and recommendations were made for improvement in performance of RCT and record keeping. Students' compliance with published guidelines was presented and their RCT performances in each year were compared using the chi-square test. RESULTS: Overall compliance with of record keeping guidelines was 44.1% in 2012, 79.6% in 2014 and 94.6% in 2015 (P = .001). In the 2012 audit, acceptable extension, condensation and the absence of mishap were observed in 72.4, 75.7% and 91.5%; in the 2014 audit, 95.1%, 64.8% and 51.4%; and in 2015 audit, 96.4%, 82.1% and 92.8% of cases, respectively. In 2015, 76.8% of root canal fillings met all 3 technical quality criteria when compared to 48.6% in 2014 and 44.7% in 2012 (P = .001). CONCLUSION: Clinical audit-feedback cycle is an effective educational tool for improving dental undergraduates' compliance with record keeping and performance in the technical quality of RCT.

Digitally Scanned Radiographs versus Conventional Films for Determining Clarity of Periapical Lesions and Quality of Root Canal Treatment.

AIM: To compare digital images of conventional radiographs with the original radiographs for perceived clarity of periapical lesions and the quality of root canal treatment. MATERIALS AND METHODS: One hundred and four intraoral periapical radiographs of patients with endodontically treated teeth were randomly selected. The radiographs were digitized using an MD300 USB X-ray Reader. The digital images were transferred to an HP laptop. Three evaluators compared each conventional radiograph with the matching digital image. The images were ranked for clarity and assessed for diagnostic quality; data were analyzed using the Reliability Calculation "ReCal." Results. Both the digital images and conventional films had comparable clarity and diagnostic quality. Results indicated a moderate agreement between the evaluators. CONCLUSIONS: Conventional radiographs digitized using an MD300 USB X-ray Reader have similar clarity and diagnostic quality in comparison to the original radiographs.

Endodontic treatment.

The Finnish guideline on endodontics emphasizes good quality of endodontic treatment and coronal seal of the restoration. For prevention of endodontic treatment need caries control is essential. For deep carious lesions stepwise excavation or partial caries removal are recommended. Partial pulpotomy can be used if bleeding can be controlled. The decision for root canal treatment is based on prognosis, occlusion and general health of the patient. The use of kofferdam is essential in aseptic working. Chemomechanical preparation with NaOCI and root canal filling within 0-2 mm from the apex improve prognosis. Healing should be controlled annually up to four years.

Interventions for the endodontic management of non-vital traumatised immature permanent anterior teeth in children and adolescents: a systematic review of the evidence and guidelines of the European Academy of Paediatric Dentistry.

AIM: This systematic review was undertaken in order to develop guidelines for the European Academy of Paediatric Dentistry for the management of non-vital permanent anterior teeth with incomplete root development. METHODS: Three techniques were considered; apexification by single or multiple applications of calcium hydroxide, use of Mineral Trioxide Aggregate (MTA) for the creation of an apical plug followed by obturation of the root canal, and finally a Regenerative Endodontic Technique (RET). Scottish Intercollegiate Guideline Network (SIGN) Guidelines (2008) were used for the synthesis of evidence and grade of recommendation. RESULTS: Variable levels of evidence were found and generally evidence related to these areas was found to be weak and of low quality. It was not possible to produce evidence-based guidelines based on the strength of evidence that is currently available for the management of non-vital immature permanent incisors. CONCLUSIONS: Based on the available evidence the European Academy of Paediatric Dentistry proposes Good Clinical Practice Points as a guideline for the management of such teeth. It is proposed that the long term use of calcium hydroxide in the root canals of immature teeth should be avoided and apexification with calcium hydroxide is no longer advocated. The evidence related to the use of a Regenerative Endodontic Technique is currently extremely weak and therefore this technique should only be used in very limited situations where the prognosis with other techniques is deemed to be extremely poor. The current review supports the use of MTA followed by root canal obturation as the treatment of choice.

Prevalence of apical periodontitis and quality of root canal treatment in an adult Saudi population.

OBJECTIVES: To determine the health status of periradicular tissue and the quality of root canal fillings in an adult Saudi population attending dental clinics for the first time. Methods: This cross sectional study was conducted  in the dental clinics at King Saud University, Riyadh and other dental centers (Jeddah, Najran, and Albaha City), Kingdom of Saudi Arabia between year 2010   and 2012. Good-quality panoramic radiographs of 926 Saudi subjects (540 males and 386 females)were analyzed based on the gender, age, health status, smoking habits, periapical status of the endodontically treated teeth, technical quality of the root canal fillings, and the presence or absence of coronal restoration. Data were calibrated and statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS Inc., Chicago, IL, USA) version 17.  Results: Of the 25,028 teeth examined, 1,556 teeth (6.2%) had apical periodontitis (AP). Male subjects aged over 55 years and females between 36 and 45 years had higher AP. A total of 36 diabetic and 87 smokers subjects had AP. The AP was more common in male diabetics than female (p=0.383), and in female smokers more than male (p=0.44). Only 42.2% of male and 57.7% of female teeth had adequate root canal treatment.  Conclusions: Apical periodontitis was significantly related to diabetes, smoking, and inadequate endodontic treatment.

Restauración postendodóncica: técnica con postes accesorios de fibra de vidrio / Postendodontic restoration: a technique with accessory fiber glass posts

Utilizar esta técnica implica grandes ventajas, ya que se reduce el volumen de cemento de resina, lo que disminuye la probabilidad de contracción, formación de burbujas y vacíos internos, los cuales representanáreas de debilidad en la restauración postendodóncica. Esta técnica ya ha sido propuesta y debidamente investigada por algunos autores. Se aplica en dientes con conductos radiculares amplios que han sido debilitados por restauraciones defi cientes, desmineralización de la dentina, fi ltraciones en la corona y poste radicular o simplementeconductos amplios en pacientes de corta edad. Tenemos la firme convicciónde que no podemos garantizar la permanencia de un órgano dentalen la cavidad oral, pero sí podemos intentar prolongar su permanenciaen el alvéolo el mayor tiempo posible. La técnica que se describe en elpresente artículo consiste en colocar postes accesorios de fi bra de vidriodespués del poste principal, logrando reducir el espesor de película delagente cementante a un grado ideal.

The use of this technique, shows significant advantages, as the thicknessof the resin cement is reduced, in consequence, the contraction ratio,bubble formation, and internal voids are reduced, which represent areasof weakness in the post-endodontic restoration, this technique has beenalready proposed and properly investigated by certain authors. Thisis applied on teeth with enlarged canals, that have been weakened byineffi cient restorations, dentin demineralization, bacterial fi ltration ofcrown and post, or simply wide canals in young patients. We have afi rm conviction, that we can´t guarantee the permanence of a dentalorgan in the oral cavity, but we can try to lengthen its permanency onthe alveolus as much as possible. The technique that´s described in thisarticle, consists in placing accessory posts of fi ber glass after placingthe main post, achieving a reduction of the cement fi lm thickness toideal thicknesses.

Prevalence of apical periodontitis in root filled teeth: findings from a nationwide survey in Finland.

AIM: To assess the prevalence of apical periodontitis in the Finnish population aged 30 years and older and relate it to the technical quality of root filling by the type of tooth. METHODOLOGY: As part of the Finnish nationwide Health 2000 study, panoramic radiographs were used of the dentate subjects (n = 5335) aged 30-95 years (mean 50.2 years) to assess the apical and endodontic status of their teeth (n = 120635). Apical periodontitis (AP) was recorded when the periodontal ligament space was more than double in width, or loss of lamina dura or a periapical radiolucent lesion was seen. Technically, adequate root fillings had a gap of 0-3 mm from the apex; all others were defined as inadequate. Statistical methods included chi-square tests and anova. Risk of AP was estimated as cross-product odds ratio and its 95% confidence interval. RESULTS: Teeth with AP occurred in 27% of the dentate subjects being more prevalent in subjects with root filled teeth than in those without (39% vs. 9%; P < 0.001; OR = 6.3; 95% CI 5.3, 7.4). AP was more prevalent in men than in women (31% vs. 23%). At a tooth level, AP was most frequent in mandibular molars with inadequate root fillings. For all root filled teeth, an inadequate root filling doubled the risk of AP for both women (OR = 2.0; 95% CI 1.7, 2.4) and men (OR = 2.5; 95% CI 2.1, 2.9). CONCLUSIONS: AP occurred principally in subjects and teeth with root fillings. Inadequate root fillings doubled the risk of AP. An improvement in the technical quality of root canal treatment is essential.

'Working in the dark': Swedish general dental practitioners on the complexity of root canal treatment.

AIM: To explore elements of reasoning and understanding that might obstruct the performance of good-quality root canal treatment (RCT) and make general dental practitioners (GDPs) produce and accept root fillings of inferior quality. METHODOLOGY: The study was designed as a qualitative and explorative study based on seven videotaped focus group interviews analysed by means of qualitative content analysis. Nine predetermined questions were followed. Thirty-three GDPs (4-6 dentists/interview), employed in the Public Dental Health Service in Gothenburg, Sweden, participated. RESULTS: Feelings such as anxiety, frustration, stress or exhaustion were associated with RCT. In general, RCT was regarded as complex, mysterious and embedded in uncertainty. A feeling of loss of control was frequently described in relation to all procedural steps from negotiating the canal to prognostic deliberations. Reasons could include challenging canals, complicated instruments and the fact that treatment had to be performed in a concealed space without visible insight. Several dentists questioned the requirements for correctly performing RCT, and some indicated that striving towards optimal technical root filling quality should not be expected in each case in general practice. Most of the GDPs were unable to complete a case within the remuneration system, and they therefore either spent more time than the set fee allowed for or accepted a suboptimal root filling when the time limit was reached. CONCLUSIONS: High levels of stress and frustration in relation to RCT were reported by the GDPs. RCT was regarded as complex and was often performed with an overall sense of lack of control.

A re-audit of the technical quality of undergraduate root canal treatment after the introduction of new technology and teaching practices.

AIM: To revaluate through re-audit the technical quality of undergraduate nonsurgical root canal treatment (RCTx) in a dental teaching hospital as a result of recommended changes to teaching practices. METHODOLOGY: The technical quality of undergraduate RCTx was evaluated radiographically after educational changes and the mandatory introduction of new technologies (nickel-titanium files, apex locators, greater taper gutta-percha points) in 182 root canals. Evaluation was based on four criteria: presence of voids, root canal filling termination (0-2 mm of radiographic apex), all roots filled and the prepared canal contained the original anatomy. Chi-squared analysis was used to determine statistically significant improvements in quality between the respective audits (P < 0.05). RESULTS: Twenty-three of the 40 canals in single-rooted teeth (57.5%) and 68 of the 129 (52.7%) canals in multirooted teeth analysed had an acceptable root filling. This compared with 48% of canals in single-rooted teeth and 38% of canals in multirooted teeth in the original audit. Specifically, the frequency of root canal voids and unsatisfactory apical root filling termination were reduced in multirooted teeth by 23% and 14% and in single-rooted teeth by 11% and 12%, respectively, compared with the original audit. When multirooted teeth were taken as one unit, 45.2% were considered to be acceptable, significantly better than the 18.8% multirooted teeth in the original audit (P = 0.042). Deviations from the canal anatomy on radiographic examination were rare findings in both audits. CONCLUSIONS: Changes to endodontic teaching practices significantly improved the technical standards of undergraduate root filling in multirooted teeth. The regular auditing of undergraduate teaching practice is necessary to inform current teaching, instigate change and improve standards.

Development of quality measurement instruments for root canal treatment.

AIM: To devise measurement instruments for 'quality' of root canal treatment to assess training and outcome of general dental practitioners working within primary care settings. METHOD: Scoring systems relating to quality of root canal treatment were developed using expert consensus and published literature. Domains scored included the Treatment Process, Quality of the Obturation, Clinical Healing, Radiographic Healing and Tooth Complexity. Scoring systems were applied to 10 clinical cases treated by each dentist at the beginning and 10 cases treated at the end of their clinical training and 135 cases treated after completion of training. The dentists recorded the treatment process and clinical healing in clinical logs. Two examiners independently scored the radiographs after undertaking calibration and training. Inter- and intra-examiner reliability of scoring radiographic outcomes was tested using Cohen's Kappa statistics. RESULTS: An instrument was created with four domains to assess quality (two for process and two for outcome of root canal treatment), and a measure of case complexity. Domains of treatment process (n = 240 teeth), outcome (n = 32 teeth) and complexity (n = 215 teeth) were scored using radiographs. The Kappa scores for intra-examiner reliability between 0.22 and 1, whilst inter-examiner reliability ranged between 0.18 and 0.99. CONCLUSION: Evidence-based scores for assessment of the quality (process and outcome) and complexity (structure) of root canal treatment were devised. They were reliable, provided that clinicians were trained in record keeping and examiners have in depth training and calibration in the use of the instruments.

Modern Endodontic Principles. Part 8: The Future of Endodontics.

Although the principles of endodontics have remained unchanged for many decades, root canal treatment has been subject to major changes in the past few years. This paper outlines the cutting-edge advances including the materials and techniques used. CPD/Clinical Relevance: This article provides an overview of bioactive materials and insight into regenerative endodontics, vital pulp therapy and intentional replantation.

[An analysis of key points for root canal therapy technique].

The success rate of root canal therapy(RCT)have been improved continuously along with the advancement in RCT techniques in the past several decades. If standard procedures of modern RCT techniques are strictly followed, the success rate of RCT may exceed 90%. The success of RCT is mainly affected by such factors as clear concept of the anatomy of root canals, proper mechanical and chemical preparation and perfect filling of root canal system. If these factors are sufficiently noted, a success is easy to achieve. Even though the primary RCT fails, retreatment can further be conducted to save the diseased teeth.

Frequency of the mesiopalatal canal in upper first permanent molars viewed through computed tomography / Frequência do canal mesiopalatino em primeiros molares permanentes superiores visualizados em tomografia computadorizada

The success of any endodontic therapy depends on factors suchas correct diagnosis and prognosis. Unawareness or failure tolocate additional canals, such as the mesiopalatal canal in theupper first molar, may lead to unsuccessful treatment. Hence,it is valid to consider all the resources available for locatingthis anatomic structure, e.g. the Cone-Beam ComputedTomography (CBCT). The purpose of this study was to verifythe frequency of mesiopalatal canals in upper first permanentmolars through computed tomography. Tomography imagesfrom a digital archive of a diagnostic imaging center wereanalyzed. Eighty (80) upper right first molars were assessedthrough CBCT in axial cross sections at 6mm and 3mm fromthe root apex; 40 were females and 40, males, randomlychosen. The results revealed that the mesiopalatal canals werepresent in 56.25% of the sections at 6mm from the root apex,and in 23.75% at 3mm from the apical limit. CBCT scan hasproved to be a valid resource for locating mesiopalatal canal,especially in cases where location was not feasible through clinical means.

O sucesso do tratamento endodôntico depende de fatores como ocorreto diagnóstico e prognóstico. O desconhecimento ou a nãolocalização de canais adicionais, como o canal mesiopalatino noprimeiro molar superior, pode levar ao insucesso do tratamento.Portanto, é válido considerar todos os recursos para localizaçãodesta estrutura anatômica, dentre eles a tomografia compu -tadorizada cone beam (TCCB). O presente trabalho teve comoobjetivo verificar a frequência do canal mesiopalatino emprimeiros molares permanentes superiores através da tomografiacomputadorizada. Os exames analisados fazem parte do arquivodigital de uma clínica de diagnóstico por imagem particular.Foram avaliados 80 primeiros molares superiores direitos emcortes axiais a 6 e 3 milímetros do ápice radicular observadosnas TCCB, sendo 40 em pacientes do gênero feminino e 40 dogênero masculino escolhidos aleatoriamente. Os resultadosrevelaram que o canal mesiopalatino está presente em 56,25%dos cortes a 6mm do ápice radicular e em 23,75% a 3mm dolimite apical. TCCB eu um recurso válido para localização docanal mesiopalatino, sobretudo nos casos em que não foi possívela sua localização clínica.

Assessing root canal fillings on a radiograph--an overview.

This article will discuss why a root filling that appears satisfactory on a radiograph may fail, and why one which appears unsatisfactory on a radiograph may succeed. In doing so, this article will also discuss the criteria of endodontic success and failure and its implications on the decision to retreat.