This systematic review aims to establish whether various irrigant activation techniques (IATs) result in greater penetration of irrigant up to the working length. The MEDLINE, Scopus and Cochrane Library electronic databases were searched to determine the difference in irrigant penetration depth in the main canal following the use of manual dynamic activation (MDA), sonic irrigation (SI), passive ultrasonic irrigation (PUI), and apical negative pressure irrigation technique (ANP) in comparison with conventional needle irrigation technique (CNI) in mature permanent teeth. Meta-analysis was performed for straight canals as well as curved canals in addition to subgroup analyses for a) Individual IATs in comparison with CNI, b) Comparison of PUI v ANP and SI v ANP in the straight canals, c) comparison of different IATs performed in straight and curved canals. The outcome was presented as effect size: standardized mean difference (SMD) and percentage difference (% diff)
of irrigant penetration up to the working length (WL) alongside 95% confidence intervals using chi-square analysis. Of the 840 records screened, 20 studies were included in the systematic review and 17 studies were included in the meta-analysis. It revealed IATs had significant improvement in irrigant delivery up to the WL in straight (% diff: 51.94%, 95% CI: 39.20–64.67%) and curved canals (SMD: 1.08, 95% CI: 0.64–1.52) over CNI. The subgroup analysis revealed ANP was the most effective and significant technique followed by PUI, SI and MDA techniques in straight canals (% diff: 91.70%, 95% CI: 75.63–107.77%) and curved canals (SMD: 1.45, 95% CI: 0.77–2.13). IATs improve irrigant penetration when compared to CNI technique. In both straight and curved canals, ANP is the most effective in delivering the irrigant up to the WL followed by PUI, SI and MDA techniques. Hence adaptation of recent IATs in routine endodontic practice is recommended. (EEJ-2022-03-036)

Inflammatory radicular cysts (IRCs) are chronic lesions that follow the development of periapical granulomas (PGs). IRCs result from multiple inflammatory reactions led initially by several pro-inflammatory interleukins and growth factors that provoke the proliferation of epithelial cells derived from epithelial cell rests of Malassez present in the granulomatous tissue, followed by cyst formation and growth processes. Multiple
theories have been proposed to help explain the molecular process involved in the development of the IRC from a PG. However, although multiple studies have demonstrated the presence of epithelial cells in most PGs, it is still not fully understood why not all PGs turn into IRCs, even though both are stages of the same inflammatory phenomenon and receive the same antigenic stimulus. Histopathological examination is currently the diagnostic gold standard for differentiating IRCs from PGs. Although multiple studies have evaluated the accuracy of non-invasive or minimally invasive methods in assessing the histopathological nature of the AP before the intervention, these studies' results are still controversial. This narrative review addresses the biological insights into the complex molecular mechanisms of IRC formation and its histopathological features. In addition, the relevant inflammatory molecular mediators for IRC development and the accuracy of non-invasive or minimally invasive diagnostic approaches are summarised. (EEJ-2022-03-041)

Objective: This study aimed to evaluate the survival from fractures and risk factors of VPT-treated permanent molars restored with direct resin composites in young patients.
Methods: The dental records of patients aged 6 to 18 years with VPT-treated permanent molars restored with resin composites were retrospectively evaluated for the presence of fractures on these teeth. Kaplan-Meier methods were used to estimate the survival probabilities. The potential risk factors were assessed using the multivariable Cox proportional hazard model.
Results: A total of 234 treated molars from 189 patients were included. An overall average follow-up time was 33.34±20.54 months (ranging from 6 to 83 months). At the end of the study, 21.8% of molars had fractures with the majority of them (92.2%) were restorable. Radiographically, only 3.9% of the fractured molars had periapical lesions and considered VPT failures. The percentages of the fracture types are as follows: 54.9% natural tooth structure fracture, 27.5% restoration fracture, and 17.6% combination fracture. The most common fracture location among the 37 molars with natural tooth fracture (either alone or in combination with restoration fracture) was at the marginal ridge (59.5%), followed by the marginal ridge extending to cusp (21.6%), and the cusp itself (18.9%). The cumulative survival probabilities of these teeth decreased over time, reaching 66.02% (95% CI: 55.89–74.36) after 5 years. VPT-treated molars in the mandible had a 2.1 times higher risk of fracture than those in the maxilla. Furthermore, the molars treated with partial and coronal pulpotomy had 2.4 times and 4.6 times higher risks of fracture when compared to those with indirect pulp capping, respectively.
Conclusion: In VPT-treated permanent molars in young patients, more fractures were seen in mandibular teeth and in teeth with pulp roof removal (partial and coronal pulpotomy). Clinicians should plan for proper restoration on these teeth. (EEJ-2022-08-097)

Objective: To evaluate the incidence of postoperative pain, treatment time and analgesic intake after single visit endodontic treatment of mandibular molars using XP-endo Shaper, 2Shape and ProTaper Gold rotary systems.
Methods: 150 patients with irreversible pulpitis were scheduled for single visit root canal treatment. Teeth were randomly assigned to one of the three groups: ProTaper Gold (PTG; Dentsply Tulsa Dental Specialties, Johnson City, TN), 2Shape (2S; Micro-Mega, Besancon, Cedex, France) and XP-endo Shaper (XPES; FKG Dentaire, La Chaux-de-Fonds, Switzerland). Preoperative and postoperative pain was rated by the patients at the beginning of treatment and after 24, 48, 72 hours and 7 days on Heft Parker’s visual analog scale (HP-VAS).
Results: Highest mean postoperative pain score was recorded in PTG (P<0.05), followed by 2S and XPES respectively at all time intervals. XPES exhibited maximum reduction from preoperative pain at 24 (48.67%) and 48 hours (96.90 %) with no pain at 72 hours. Treatment time was significantly least in XPES (P<0.05) followed by 2S and PTG; but no significant difference in analgesic intake was noted.
Conclusion: XPES exhibited least postoperative pain at all time intervals and treatment time, followed by 2S and PTG rotary systems respectively. (EEJ-2022-04-053)

Objective: The aim of this study was to evaluate postoperative pain after non-surgical root canal retreatment with or without GuttaClear.
Methods: Sixty participants were randomly distributed in this non-inferiority trial into two parallel singleblinded experimental groups (Group1: non-solvent, Group2: solvent). After root canal retreatment, the participants completed questionnaires using direct (numerical rating scales) and indirect (number of analgesics taken) measurements of postoperative pain at immediate, 6, 12, 24, 48, and 72 h post-retreatment. The predisposing postoperative pain factors were recorded and analysed using Generalized Estimating Equations to identify correlated factors (α=0.05).
Results: The pain incidence was not significantly different between the groups at any time point. The highest incidence of postoperative pain occurred immediately after retreatment (35%) and then decreased to 15% at 24 h (P<0.05). The number of participants requiring analgesics was 6.67% in the non-solvent group and 9.99% in the solvent group which were similar between the groups. Patients with a history of previous postoperative pain were 21.6-fold more likely to have postoperative pain than those without (P<0.05).
Conclusion: There was no difference in postoperative pain or analgesics required after root canal retreatment with or without using GuttaClear. This study is registered in ClinicalTrial.gov (NCT04326998). (EEJ-2022-05-069)

Objective: To test the hypothesis that the (i) presence of non-carious cervical lesions (NCCLs) and (ii) type of post system have no effect on the fracture resistance and pattern in endodontically treated maxillary premolars.
Methods: Human maxillary first premolars (n=60) with two root canals were randomly allocated into four groups (n=15). Buccal wedge-shaped NCCLs were prepared in 45 teeth specimens. Following root canal treatment, the specimens were randomly divided into (i) composite resin core (CRC); (ii) NCCLs + composite resin core (NCCL+CRC); (iii) NCCLs+prefabricated fibre-reinforced composite post + composite resin core
(NCCL+PFRC+CRC); (iv) NCCLs+custom fibre posts + composite resin core (NCCL+CFP+CRC). All specimens were subjected to thermocycling (5°C to 55°C/5000 cycles). The compressive load was applied non-axially to the palatal cusp with a universal testing machine at a crosshead speed of 0.5 mm/min at a 30° angle until fracture. Fracture patterns were examined using a loupe magnification (2.5×) under transillumination. Statistical analyses were performed using non-parametric tests and pairwise comparisons of the load-to-fracture
among the groups. Chi-square test was used to analyse the fracture patterns (P=0.05).
Results: Fracture resistance of NCCL+PFRC+CRC was significantly higher than NCCL+CRC (P=0.011), while NCCL+CFP+CRC did not show any significant difference when compared to NCCL+CRC (P=0.089). No statistical difference was found between CRC, NCCL+PFRC+CRC and NCCL+CFP+CRC (P=1.000). The frequencies of favourable fracture patterns in descending orders were as follows: CRC (80%), NCCL+CFP+CRC (73%), NCCL+PFRC+CRC (60%), and NCCL+CRC (40%). Chi-square test did not show significant differences in fracture
patterns among all groups (P=0.110).
Conclusion: Restoration of the endodontically treated maxillary premolars with NCCLs, with or without post, resulted in similar fracture resistance as their counterparts without NCCLs. Placement of a prefabricated fibre-reinforced composite post exhibited greater fracture resistance to the maxillary premolars with restored NCCLs than those without a post. (EEJ-2022-06-077)

Objective: This study was performed to assess smear layer formation and erosion after final irrigation protocols with metal and non-metal tips in the apical third of root canals.
Methods: Forty mandibular premolars were instrumented with ProTaper Gold files up to F3 and embedded in a closed silicone flask system. The teeth were subsequently cleaved and 4 sequential indentations (1 to 4 mm from the apical foramen) were prepared on the buccal root canal walls to standardize sites for environmental scanning electron microscopy (ESEM) imaging. The samples were cleaned in an ultrasonic bath and observed under ESEM (controls), reassembled and divided into four groups (n=10 each) and subjected to different final irrigation protocols; XPF Group (XP-endo Finisher) and PUI Group (passive ultrasonic irrigation) with metal tips; EA Group (EndoActivator) and MDA Group (Manual dynamic agitation) with non-metal tips. The smear layer formation and dentine erosion were evaluated using ESEM. The data were analyzed with Kruskal-Wallis test with Bonferroni correction.
Results: In comparison to the control groups, XPF group had significantly increased smear layer formation at 1 and 2 mm (P<0.05). PUI group had significantly higher smear layer (P<0.05) formation at 3mm while EA and MDA groups did not present with significantly higher smear layer at all levels. Erosion was significantly higher (P<0.05) in MDA, XPF and PUI groups at all levels when compared to controls while EA group presented with significantly more erosion only at 2 and 3 mm.
Conclusion: Final irrigation protocol using EA and MDA with non-metal tips did not result in significant smear layer formation. Dentine erosion was observed after all experimental irrigation protocols. (EEJ-2021-12-194)

Objective: According to the American Association of Endodontists (AAE), 22 million endodontic procedures have been performed annually. Root canal treatment is needed to prevent infection and restore function when a tooth is severely infected or decayed. This procedure is the only way to preserve the natural tooth and avoid artificial replacement (implant, denture, etc.). The current study aims to develop an electrochemical reamer (EC-Reamer or EC-R) that can help to disinfect the canal system and thus improve the success rate of root canal treatment.
Methods: The COMSOL Multiphysics software was utilized to simulate the experimental setup and confirm the current flow in the electrolyte. The benchtop experimental approach follows a specific electrochemical protocol, (i) open circuit potential to monitor the electrochemical stabilization and (ii) potentiostatic scan at –9.0 V as the treatment stage. Identification of feasible reference electrode (RE) and insulation material for the exploratory benchtop studies considered platinum (Pt) and gold (Au) wire as the REs and hot melt adhesive (HMA) and liquid tape as the insulation materials. The antimicrobial effects of EC-R were analysed using Enterococcus faecalis (E. faecalis). One-way ANOVA with the Tukey post hoc test and a significance level of P<0.05 is used to compare the groups with an experimental duration of 60 seconds.
Results: The findings showed that magnitude and current fluctuations created by Pt wire are promising when compared to Au wire, while Pt–HMA pair is chosen considering Pt's good electrochemical inertness and HMA's easy handling, availability, and non-hazardous features. The use of potentiostatic duration of 1 s and 3 s resulted in >99.99% E. faecalis reduction. Duration at 5 s and above resulted in a total bacterial kill. Statistical analysis confirmed a significant difference among the groups tested with commercial and custom-built potentiostats.
Conclusion: The outcome provided preliminary data for developing an EC-R prototype to enhance the antimicrobial effect during root canal treatment potentially. (EEJ-2022-01-04)

Objective: The high prevalence of chronic kidney disease in the community, especially in older patients, makes their management an important aspect of clinical practice. The aim of this study was to evaluate the knowledge attitudes and performance of Iranian endodontists regarding patients with chronic kidney disease (CKD).
Methods: This cross-sectional, descriptive-analytical study involved 100 Iranian endodontists (41 M, 59 F), who completed questionnaires with 21 items on CKD. Responses were analyzed by SPSS, using Chi-square or Fisher's exact tests.
Results: Overall levels of knowledge were rated as optimal in 55% of subjects, while attitudes to care were favourable in 83%. This cohort of specialist clinicians had strong scores for optimal attitude and performance. Awareness of issues around prescribed analgesics, antibiotic cover, bleeding risk and hypertension was high. Proximity to specialist training (younger specialists, and less years in practice) and female gender were associated with significantly higher scores across the three domains measured.
Conclusion: Most specialists were aware of requirements for safe care of dental patients with CKD. Continuing professional education should target older clinicians who may have had less exposure to formal training in this topic during their clinical training. (EEJ-2022-04-059)

In addition to pathogenic teeth associated with cysts, the roots of adjacent teeth are often included in the cystic cavity. Whether these teeth require elective endodontic treatment followed by cystic enucleation remains unclear. In the case presented herein, we aimed to preserve the pulp of the teeth included in the cystic lesion. Unfortunately, the sensibility of the included teeth was negative after endodontic surgery, including cystic enucleation. However, the sensibility recovered after 1 year and was maintained throughout a 4.5-year follow-up. Therefore, we suggest that elective endodontic treatment of the included teeth should be avoided, and further research should be conducted regarding this issue. (EEJ-2022-05-063)

Periapical lesions of endodontic origin are fairly common in the oral cavity in association with tooth pulp infection. Most of these lesions will resolve with adequate root canal treatment and rarely cause suspicion of more insidious disease. Most clinicians tend to skip histopathological examination in cases where the lesion is excised or curetted. We present a rare case of mucinous adenocarcinoma in association an endodontically treated maxillary discoloured central incisor in a 38 year old patient with a history of root canal treatment about 15 years ago. Root canal re-treatment and wide excision was performed. Histology showed epithelial islands suggestive of a neoplasm. Immunohistochemistry was positive for CK7 and S100. Metastasis was ruled out and no evidence of recurrence has been noted in the 12-month follow up period. It is emphasized that any tissue removed from the surgical site should be analysed microscopically. (EEJ-2022-01-013)