Adequate understanding and accurate characterization of normal and unusual root and canal morphology are essential requirements for successful root canal treatment. A new coding system for classifying root and canal morphology, accessory canals and anomalies has been introduced. In addition to technological advances related to experimental studies involving micro-computed tomography, the continuing clinical advances in magnification, illumination, imaging and intra-operative root canal treatment procedures have allowed clinicians to identify an increasingly wide range of anatomical variations in roots and canals in an attempt to achieve more predictable clinical outcomes. This review aims to provide a step-by-step explanation for the clinical application of the new coding system in dental practice, and to describe the anatomical variations in roots and canals for teeth scheduled for root canal treatment. (EEJ-2021-01-08)

This systematic review compares polytetrafluoroethylene tape and cotton pellet when used as endodontic spacers underneath provisional restorations. The review followed the PRISMA guidelines and was registered in the PROSPERO database (CRD42020176555). Studies that compared the microbial contamination between polytetrafluoroethylene tape and cotton pellet, when used as spacers, were included. Literature searches of Pubmed, Embase, EBSCOHost Dentistry & Oral Sciences Source, Scopus, and Open Grey databases were conducted from their inception until May 2020 for studies in English or other Latin script languages. Hand searching of reference lists was performed. Three laboratory and three clinical studies were included. The risk of bias of the component studies varied widely. Results from the laboratory studies showed higher bacterial counts for cotton pellets. Results from the clinical studies showed that polytetrafluoroethylene tape was associated with a significantly lower incidence of microbial contamination. Findings were consistent throughout the studies, though the evidence available is scarce and heterogeneous. Polytetrafluoroethylene tape was associated with less microbial contamination when compared with cotton pellets as endodontic spacers and therefore appears to be a more suitable material for the purpose. (EEJ-2021-04-066)

Objective: The aim of this study was to evaluate the sensitivity and specificity of electric pulp testing (EPT) using the bridging technique in comparison to a cold test on crowned teeth.
Methods: Thirty teeth were included in this study. Only one crowned tooth from each subject was included. The adjacent teeth served as controls. The crowned teeth were tested for pulp vitality using a bridging EPT technique and cold test. Vitality was confirmed upon access based on bleeding or lack of bleeding from detected root canal systems. The data was statistically analyzed using the McNamara test (P<0.05).
Results: The sensitivities of the cold test and bridging EPT were 87% and 66% respectively. Accuracy for cold and bridging EPT were 87% and 67% respectively. The cold test demonstrated a statistically significant higher accuracy and sensitivity than the bridging EPT. However, no significant difference was detected in the specificity between the two tests.
Conclusion: Both EPT and cold test should be considered as an adjunctive diagnostic tool when determining pulp status in a crowned tooth. Pulp sensitivity tests are essential but the results should be interpreted in combination with other clinical signs/symptoms. (EEJ-2020-05-111)

Objective: The purpose of this study was to investigate the pulpal effect of diode low-level laser therapy (LLLT) of 810 nm on the alleviation of pain in patients requiring dental procedures.
Methods: The current study was a double-blind randomized clinical trial carried out on twenty participants. The electric pulp testing (EPT) was recorded at baseline. Patients were randomly divided into sham laser and laser group respectively receiving low-level laser with placebo and active probes. Low-level laser at 810 nm, 200 MW constant power, 30s irradiation time and energy dose of 6 J was used. The electric pulp testing (EPT) method was again adopted to assess the rate of induced anesthesia. Laser and sham laser treatments were carried out in two different sessions with a one-week interval to ensure avoiding the potential false placebo results. Data were analyzed in SSPS-24 using Chi-square test and t-test. The p-value was set at 0.05.
Results: A low-level laser at 810 nm significantly alleviate EPT-induced pain compared to the pain before laser irradiation (P≤0.001). While the difference of EPT-induced pain before and after sham laser irradiation was not significant in control group (P>0.05). There was no correlation between the anesthetic effects of a laser application at 810 nm and other variables including age and gender (P>0.05).
Conclusion: An 810 nm low-level laser is a powerful device for induced anesthesia applications in patients requiring dental procedures. It also lessens the patients' fear of dental procedures. (EEJ-2020-04-074)

Objective: To identify the distribution and characteristics of cracked teeth in a Southern Nevada population attending the dental clinics of the School of Dental Medicine, University of Nevada, Las Vegas (SDM, UNLV).
Methods: A retrospective keyword search of the clinical notes of SDM, UNLV patient charts in AxiUm™ was performed using the search terms “crack” and “fracture” to discern the number of patients that had clinically identifiable teeth with cracks, and which teeth (if any) had documented symptoms consistent with the cracks. The inclusion criteria for the record search were individuals ≥18 years old, seen at the dental clinic between 2010 and 2018. Demographic data were analyzed using a Chi-square test against the demographics for Clark County’s population.
Results: 893 patients presented with cracked teeth, of which 41% had documented symptoms. Patients in the 45-54 age range had the highest number of teeth with cracks (P<0.001). Males comprised 49% of the cases. Caucasians (58.9%) and African Americans (21.1%) represented a majority of the population with cracked teeth (P<0.0001). 1st and 2nd molars had the highest predilection for fractures (59.8%).
Conclusion: Mandibular and maxillary first and second molars were amongst the highest teeth affected with cracks. (EEJ-2020-06-154)

Objective: Since the 1960s, there has been contradictory evidence regarding the association between periodontal pathology and the status of the pulp. The purpose of this study was to evaluate the histopathological changes of pulp tissue with severe periodontal disease, including vertical bone loss involving the major apical foramen, and compared them with the histological pulpal status of teeth with healthy periodontium.
Methods: This case-controlled study included 35 intact teeth with severe periodontitis of hopeless prognosis (test group) and 35 teeth without periodontitis extracted for orthodontic reasons (control group). For each tooth, periodontal and endodontic parameters such as probing depth and pulpal vitality were recorded, and the pulp tissue was evaluated histologically. The data were analysed with a significance level of 0.05.
Results: Vital pulp was observed in all specimens of both groups (P=1). Pulpal inflammation in the apical portion was observed in 81.71% of the severe periodontitis group, whereas all teeth in the control group demonstrated no signs of pulpal inflammation. Dystrophic calcification and pulp stones were observed in 7.5% of the periodontitis group and 5.7% of the healthy group (P>0.05). Pulp fibrosis was observed in 22.8% of the periodontitis group and 2.8% of the control group (P=0.012). Pulpal necrosis was not noted in either group. In the periodontitis group, internal resorption was present in 22.8% of cases (P=0.005) and external resorption was present in 80% of cases (P<0.001). In the control group, no internal or external resorption was observed in any of the specimens. No differences were noted in the study patients with regard to sex or age.
Conclusion: Periodontal disease does not significantly affect pulp vitality and pulpal calcifications. However internal and/or external resorption was significantly different between the two groups as well as apical inflammation and pulp fibrosis. (EEJ-2020-10-241)

Objective: There are no reports in the literature on whether FGP geometry influences the bond strength of the endodontically restored tooth. This study aimed to determine the stress distribution and the pull-out bond strength of different FGP geometries, before and after chewing loads simulation.
Methods: One hundred and twenty root analogues were prepared and randomly distributed in six groups according to the post geometry. Half of the specimens were aged in water at 37 °C using a mechanical fatigue machine (84 N, 2 bar, 45°, 106 cycles, 4 Hz); while the remaining specimens were immediately submitted to the pull-out bond strength test. The specimens were tested in a universal testing machine and the bond strength in MPa was calculated. To assess the stress concentration, the finite element method was used simulating the same post geometries that were used in the in vitro test.
Results: Two-way ANOVA (95%) showed no influence of post geometry on the bond strength (P=0.055) while fatigue cycling was statistical significant to reduce the bond strength values (P=0.000). The factors interaction was significant (P=0.019); however, TUKEY test (5%) showed no significant difference between post geometries after mechanical cycling. The tensile stress result showed critical areas in the post's cervical region regardless of the design.
Conclusion: The FGP geometry does not affect the root stress distribution and the long-term bond strength. However, FGP that allow a reduced cement layer thickness can improve the immediate pull-out bond strength value. (EEJ-2020-09-217)

Objective: This study investigated the flow of an endodontic irrigant in a single-rooted tooth with internal root resorption (IRR).
Methods: A simulation of a prepared central incisor with internal root resorption was created and irrigation with a 30-G needle was performed. The fluid pattern of the irrigant was evaluated using a Computational Fluid Dynamics model. In addition, the effects of the needle-insertion depth in the root canal and the size of root resorption on the fluid flow and the wall shear stress (WSS) values were assessed. The IRR was placed immediately below the canal orifice.
Results: Inadequate irrigant washout was observed inside the resorption cavity when the needle was positioned 1 mm from the working length while placing the needle slightly above the resorption cavity resulted in significant irrigant circulation inside the resorption cavity. Moreover, when the needle was placed slightly above the defect, the calculated WSS values in the resorption cavity walls were significantly higher (approximately 20 times higher in every case). In cases where the needle was placed 1 mm from the working length, the average and maximum WWS values were between 3 Pa and 51 Pa, while in cases where the needle was placed coronal to the IRR, the values were between 55 Pa and 528 Pa. The radius of the resorption cavity did not affect the irrigant flow patterns.
Conclusion: During the endodontic treatment of cases with internal root resorption, complementary irrigations with the needle tip placed slightly above the resorption cavity should be followed to better debride the root canal. (EEJ-2020-12-281)

Objective: The bioactivities of TotalFill BC and the MTA Fillapex sealers were evaluated.
Methods: Sixty horizontal root sections were enlarged to size 5 Gates Glidden and randomly divided into six groups (n=10 in each group). In Groups 1–3, sections were filled with TFBCS, while sections in groups 4–6 were filled with MTAFS. Specimens from groups 1 and 4 were soaked in simulated body fluid (SBF) for one day, those from groups 2 and 5 for one week, and those from groups 3 and 6 for two months. All specimens were processed for scanning electron microscope (SEM) examination. Apatite precipitation on sealer and sealer–dentine interfaces was quantified using image analysis software (ImageJ). Energy dispersive X-ray (EDX) was used to analyse calcium (Ca) and phosphate (P) contents of surface precipitation on which calculation of the calcium phosphate (Ca/P) ratio was based.
Results: TFBCS samples, regardless of the duration of SBF soaking, yielded a significantly higher surface area of precipitation compared to MTAFS (P<0.05); such precipitation increased over time, and the differences among the three time-points were also statistically significant. Following one day of SBF soaking, MTAFS samples showed only limited precipitation that started to appear after one week. EDX showed that Ca content and the Ca/P ratio of surface deposits on TFBCS samples increased over time with no difference between one week and two months of SBF soaking. The Ca content and Ca/P ratio of surface deposits on MTAFS were significantly lower than that of TFBCS samples regardless of the SBF soaking time.
Conclusion: Ageing TotalFill BC sealer in SPF can induce considerable apatite formation. In addition, the TotalFill BC sealer surface showed high Ca2+ ion release as reflected by the formation of apatite with a high Ca/P ratio. These bioactivity features increased over time. In comparison, the MTAFS appears to have lower and delayed bioactivity. (EEJ-2019-12-121)

Objective: To assess and quantify coronal tooth discolouration by ProRoot MTA, Biodentine and MTA repair HP as pulpotomy agents and to identify colour stability of these materials in presence of blood contamination.
Methods: 120 human premolar teeth were used in the study. The teeth were sectioned horizontally 1 mm apical to the cementoenamel junction. A retrograde cavity extending within 2 mm of the incisal edge was prepared. The specimens were randomly distributed as; Control: Group 1, ProRoot MTA: Group 2, Biodentine: Group 3 and MTA repair HP: Group 4. The groups werefurther subdivided on basis of exposure to saline (subgroup A) or blood (subgroup B). The access was sealed with light cured Glass ionomer cemet and the specimens were stored in artificial saliva at 37°C. The Colour change was evaluated with a spectrophotometer at: day 0 (T0), day 1 (T1), day 7 (T7), 1 month (T30), 2 months (T60), and 6 months (T180). The colour measurements were recorded using the Commission Internationale de l'Eclairage L*a*b* value.
Results: For all groups, there was a sharp increase in L* parameter at T1. At 6 months, Group 1B (Control + blood) showed maximum decrease in luminosity followed by Group 2A (ProRoot + saline) > Group 4B (MTA repair HP + blood) > Group 2B (ProRoot + blood). Group 3A (Biodentine + saline) showed the least amount of decrease in luminosity followed by Group 4A (MTA repair HP + saline) and Group 3B (Biodentine + blood). No significant difference was found in ∆E change between any of the groups from baseline to 180 days (P>0.05).
Conclusion: Relative to L* parameter, it was possible to observe a statistically significant decrease in luminosity in the Group1B (Control + blood) followed by ProRoot MTA (Group 2A and 2B) and MTA repair HP (Group 4A and 4B). Biodentine (Group 3A and 3B) showed least tooth discolouration in terms of L* parameter. (EEJ-2020-11-261)

Objective: TruNatomy and XP-endo Shaper are recently introduced file systems showing increased fatigue resistance rate. The present study aims to evaluate the surface topographic changes and nickel (Ni) and titanium (Ti) elemental loss of XP-endo Shaper (XPS) and TruNatomy (TN) files on exposure to conventionally used root canal irrigants; [5.25% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA)] at a 10 minute time frame using atomic force microscopy (AFM) and energy dispersion X-ray spectroscopy (EDX) analytical techniques.
Methods: Twelve samples for each of XPS (30/.04 taper) and TN (26/.04 taper; prime) instruments were dynamically exposed to 5.25% NaOCl, 17% EDTA separately for 10 minutes and in combination of 5.25% NaOCl (8 minutes)+17% EDTA (2 minutes) for a total of 10 minutes. Post exposure, the files were subjugated to AFM and EDX analysis. Independent t test and one-way ANOVA were used for statistical analysis, and the level of significance was set at 0.05.
Results: XPS and TN showed a significant increase of surface roughness (Ra) and roughness mean square (RMS) on exposure to various irrigants (P<0.05) using AFM analysis. Increased overall roughness was observed with TN in comparison to XPS (P<0.05). Elements Ni and Ti loss was found in both XPS and TN files using EDX analysis. Both files exhibited Ni and Ti loss with the loss of Ni content higher for TN after exposure to 17% EDTA. Loss of Ti was seen for both files on exposure to a combination of 5.25% NaOCl+17% EDTA.
Conclusion: After exposure to root canal irrigants, the surface roughness was lesser in XPS compared to TN files. 17% EDTA caused significantly higher surface roughness in both file systems when compared to 5.25% NaOCl. TN exhibited overall higher elemental (Ni and Ti) loss on exposure to 17% EDTA and 5.25% NaOCl+17% EDTA in comparison to XPS files. (EEJ-2020-12-275)

Objective: E. faecalis is one of the most commonly found species in persistent and secondary infections associated with endodontic failure. This in vitro study aimed to evaluate the depth of penetration and antimicrobial efficacy of 5% and 10% bamboo salt (BS), 2% chlorhexidine gel (CHX) and calcium hydroxide (CH) against E. faecalis.
Methods: E. faecalis was inoculated in dentine blocks for 21 days following which the antibacterial efficacy of the experimental medicaments were quantatively assessed by harvesting the dentinal debris from depths of 200 µm and 400 µm from the block lumen on the 2nd and 7th day. The depth of penetration of the medicaments was measured using LIVE/DEAD BacLight stain under CLSM.
Results: Results showed that the medicaments had varying degrees of antimicrobial efficacy and depth of penetration. Among the medicaments, CHX showed the highest antimicrobial activity on both the time intervals (P<0.05), followed by 10% BS, 5% BS and the least efficacy was observed in CH group. CHX and 10% BS exhibited the highest depth of penetration, which was proximate to the penetration of E. faecalis.
Conclusion: It can be concluded that 10% bamboo salt can serve as a viable natural antimicrobial in endodontic therapy. (EEJ-2021-01-03)

Objective: The aim of the present study was to evaluate the effect of different pHs (4.4, 5.4, 6.4, 7.4, 8.4, and 9.4) and three different particle sizes of bismuth oxide on diametral tensile strength (DTS) of white Mineral Trioxide Aggregate (WMTA).
Methods: Thirty cylindrical moulds were divided into six groups of five; WMTA was mixed, placed inside the moulds, and wrapped in pieces of gauze soaked in synthetic tissue fluid (STF) with pH values of either 4.4, 5.4, 6.4, 7.4, 8.4, 9.4. For bismuth oxide, eighteen similar molds were divided into three groups of six (n=6). Then bismuth oxide with three particle sizes, including fine (120 nm), medium (200 nm), and coarse (10 μm), were provided and added to the Portland cement, which did not have any bismuth oxide to create WMTA. Then WMTA was mixed, placed inside cylindrical molds. After incubation at 95% humidity for 48 hours, samples were subjected to DTS testing by an Instron Universal testing machine with a crosshead speed of 1 mm/min. Then, one sample from each group was subjected to scanning electron microscope (SEM) analysis. Data were analysed by ANOVA and Tukey tests (α=0.05).
Results: The comparison of DTS in pH groups were: 8.4>7.4>9.4>6.4>5.4>4.4 (P<0.05); and in bismuth oxide groups were: fine particles > medium particles > coarse particles (P<0.05). Acidic pH, negatively affected the distribution of Ca2+ and Si4+ ions, while bismuth oxide with fine particles enhanced it.
Conclusion: Acidic pH can decline the DTS of MTA significantly. However, reducing the particle size of bismuth oxide can increase the DTS of MTA significantly.
Conclusion: Acidic pH can decline the DTS of MTA significantly. However, reducing the particle size of bismuth oxide can increase the DTS of MTA significantly. (EEJ-2020-06-132)

Objective: The aim of this study was to compare and evaluate the dentinal tubule penetration and adaptation of a premixed bioceramic sealer and an epoxy-resin based sealer in the three radicular thirds.
Methods: 30 wide roots, with single straight canals and totally formed apexes, were endodontically prepared and divided into two groups (n=14) according to the sealer used for root canal filling: AH-Plus (AHP) and Bio-C Sealer (BIOC). Two samples were left as controls. After the canals were filled, the samples were cut and viewed under Scanning Electron Microscopy by taking images to analyse the tubular penetration and adaptation of the sealers. The results were statistically analysed with the Shapiro Wilk, Levene and Mann-Whitney tests (P<0.05).
Results: BIOC showed significantly higher penetration in dentinal tubules than AHP in the cervical, middle and apical thirds of the root canal (P<0.05) and better adaptation to the dentinal tubule walls.
Conclusion: Under the parameters of this study, BIOC exhibits higher penetration and better adaptation to the dentinal tubules compared to AHP. (EEJ-2020-06-152)

Objective: To compare the amount of apically extruded bacteria between hand-filed preparations, rotary and reciprocation glide path preparations in curved canals of extracted teeth infected with Enterococcus faecalis.
Methods: Forty mandibular first molar teeth were decoronated, fitted into rubber stoppers and fixed onto glass vials. The mesiobuccal canals from mandibular first molar teeth were infected with Enterococcus faecalis, then randomly assigned to one of five groups for glide path preparation: manual stainless-steel file (K-files), rotary file (One G), reciprocating file (WaveOne Gold Glider) and two control groups. After glide path preparation, 0.01 mL of saline was taken from the experimental vials. The solution was plated on tryptic soy agar and colonies of bacteria were counted as colony-forming units. The results were analysed statistically using Kruskal-Wallis and post hoc Mann-Whitney U tests.
Results: The manual K-file group was associated with significantly more bacteria extrusion compared to the rotary and reciprocating groups (P<0.05). However, no significant difference occurred between rotary and reciprocation instruments.
Conclusion: All instrumentation techniques resulted in a measurable amount of apical extrusion of bacteria. Manual K-files extruded the highest quantity of bacteria compared to One G rotary file and WaveOne Gold Glider reciprocation file during glide path preparation. (EEJ-2020-06-148)

Objective: Preventing bacterial overgrowth is an essential component of successful root canal treatment. Increasing the penetration of antimicrobial substances into the canal through electrophoresis is one of the possible methods. This study aimed to measure the copper ions extruding from the root apex after using an electrophoresis device (Depotphorese®) in human teeth with single canals.
Methods: In this ex-vivo study, thirty extracted human teeth with single canals were randomly divided into 2 groups. Group 1 as root canal preparation (WP) and group 2 as control (without root canal preparation). Each sample was individually fixed by alginate in a 5 ml sterile Eppendorf tube (microcentrifuge tube), and the root end was in contact with the distilled water solution. Ions derived from calcium hydroxide plus cupper paste (Cupral®) which mobilized via a low current electric field (1.5 mA/min for10 min) by Depotphorese® device. The copper ions in water solution were measured by spectrophotometric and supernatant methods.
Results: Copper ions were extruded from the end of the apex in two groups. However, based on the results of the t-test; copper ion penetration was significantly lower in the control group compared to the WP group (P<0.05).
Conclusion: Electrophoresis increased copper extrusion from the apical foramen. Although the root canal preparation increases the copper ion output in an ex-vivo environment, the amount of copper extruded from the root apex end was lower than the toxic dose. It seems that electrophoresis of copper plus calcium hydroxide mixture in endodontic treatments can be a safe procedure. (EEJ-2020-06-150)

Objective: To evaluate the push out bond strength of a glass fibre post to root dentine pretreated with 6.5% proanthocyanidin (PAC) and 0.02% phytosphingosine (PHS).
Methods: Thirty-three freshly extracted single rooted human teeth were decoronated to a length of 14 mm. Root canals were prepared using rotary NiTi files and obturated with gutta percha and resin sealer. Post space was prepared using peeso reamers, retaining 5 mm of apical gutta percha. Following smear layer removal and acid etching of the post space, samples were randomly assigned to 3 groups based on the dentine pretreatment, namely the control (no pretreatment) group, 6.5% PAC group, and 0.02% PHS group. A glass fibre post was luted using a dual cure adhesive and luting cement. 1 mm thick root slices were sectioned from coronal, middle and apical levels of the post and their push out bond strength was evaluated using a universal testing machine. Data was analysed with one-way ANOVA and Games-Howell post hoc test (P<0.05).
Results: At all levels, PHS showed higher push out bond strength than PAC and control groups, with a significant difference between the experimental groups at the middle and apical thirds (P<0.05). The push out bond strength of PAC group was significantly higher than the control group in the coronal and apical thirds (P<0.05).
Conclusion: Both PAC and PHS improved the push out bond strength of a glass fibre post to dentine. (EEJ-2020-12-285)

Objective: This study aimed to evaluate unsuccessful endodontic surgery cases for possible causes for treatment failure and evaluate if a nonsurgical retreatment (NSRTX) approach could have been a better alternative to resurgery.
Methods: Analyses of clinical and cone-beam computed tomography (CBCT) images, periapical radiographs, and chart documentation determined study parameters. Preoperative factors were age, sex, tooth type, signs and/or symptoms, presence of periapical radiolucency, previous root canal treatment, timeline since previous endodontic surgery, presence of posts, cores, and restorations. The intra-operative factors were microsurgical classification, previous techniques, and current techniques utilized. Postoperative factors were signs and/or symptoms, time to follow-up, and healing status. The accessibility of the root canal system and the quality of the existing root filling were used to evaluate NSRTX as an alternative to resurgery.
Results: A total of 1073 surgical cases from 2011-2019 were reviewed. In 14 patients, 20 cases matched the inclusion criteria and allowed for data extraction. The mean time since the previous surgery was 2.9±2.1 years, with a mean follow-up of 9.1±5.8 months after the resurgery. Possible reasons for failure identified were: insufficient root-end filling (leaking, off-axis preparation, lack of depth, overfill) n=12/20, 60.0%; missed anatomy (main and lateral canals, isthmus) n=9/20, 45.0%; incomplete resection n=6/20, 30.0%. In 18/20 cases (90.0%), resurgery appeared to be indicated for 2/20 cases (10.0%). Therefore, NSRTX may have been a potential alternative.
Conclusion: Further evidence for possible causes of failure of endodontic surgery was provided, which were primarily iatrogenic. The evaluation of CBCT and high magnification intra-operative images proved beneficial for identifying critical issues for all investigated cases. (EEJ-2021-02-022)

Although regenerative endodontic procedures (REPs) have become one of the widely accepted treatment modalities for necrotic immature teeth with apical periodontitis, little is known about the long-term outcomes and the effect of orthodontic tooth movement on this procedure. This report presents a case that underwent two REPs and orthodontic treatment over a period of seven years. A 9-year-old male was referred for evaluation of traumatized maxillary central incisors. Based on clinical and radiographic examinations, a diagnosis of pulp necrosis with acute apical abscess was established. REP was performed for both teeth, and the patient was brought in for follow-up annually. Orthodontic treatment was performed during the follow-up period. Annual follow-up visits demonstrated complete resolution of signs and symptoms of disease with the thickening of the roots. At the six-year follow-up visit, the patient presented with a sinus tract and periapical radiolucency. A second REP was performed for both teeth. The one-year recall visit after the second REP revealed complete resolution of clinical symptoms and radiographic signs of healing of apical pathology with further development of the roots. In conclusion, the effect of orthodontic treatment on teeth undergoing REP should be investigated and yearly follow-up visits should be recommended for patients undergoing REP as this case showed signs of deterioration six years after the treatment. (EEJ-2020-05-126)