Objective: This study aims to compare the pain perception associated with the needle-free system (Comfort-In™) and the standard needle injection method during root canal treatments in adults.
Methods: Forty-four maxillary premolar teeth of the patients that applied to university for treatment and needed endodontic treatment were included in the study. Patients were anesthetized with two different injection methods; needle-free injection and conventional dental injection. In both groups, oxygen saturation and pulse measurements of the patients were recorded at 30-second intervals for 2 minutes before anesthesia and 4 minutes after anesthesia. Pain during the injection and opening of the access cavity preparation was recorded according to Visual Analog Scale (VAS). The data were analyzed according to a statistical program.
Results: In this study, a significant difference was found between the groups in terms of pain during anesthesia administration and the access cavity preparation (p<0.001). There were no significant differences in terms of gender and age (p>0.05). There was no significant difference between the groups in terms of oxygen saturation and pulse values before and after treatment (p>0.05).
Conclusion: Needle-free injection makes the treatment more comfortable for patients with injection fear and anxiety, making the procedure easier for the physician and the patient. (EEJ-2024-12-197)

Objective: This study investigated the morphology of accessory canals in the mandibular first molar of a Malaysian subpopulation.
Methods: A total of 140 mandibular first molars were scanned using micro-computed tomography. The accessory canals for each of the mesial and distal roots were classified according to Ahmed et al. system based on location (coronal, middle and apical thirds) and type (patent, blind, loop and delta). A total of thirty mandibular first molar teeth were used for calibration. The Chi-square and Chi-square goodness-fit tests were used to assess the association between the categorical variables. The significance was set at 0.05 (p<0.05).
Results: Results showed that the prevalence of accessory canal is 80.71%. The apical third was the most common location for accessory canals in the mesial (79.3%) and distal (75.9%) roots (p<0.001). Amongst accessory canal types, the patent type was the most common (76.43% and 71.43%, respectively) with the codes of M(A1), D(A1). No significant association was found between root type and the presence of the accessory canals (p=0.071). A significant difference was found in the type of accessory canals and the location within the root (p<0.001).
Conclusion: In this population, the mandibular first molars showed a high prevalence of accessory canals in the mesial and distal roots. Patent accessory canals in the apical third are the most common in both roots followed by apical delta. (EEJ-2024-10-163)

Objective: This case-control study aimed to explore the expression of different osteogenic-related genes in inflamed dental pulp and to correlate these expressions amongst each other and with the extent of pain.
Methods: Dental pulp tissues were collected from patients who were diagnosed with irreversible pulpitis. All samples were processed for RNA extraction and analysis of bone morphogenic protein 2 (BMP2), RUNX family transcription factor 2 (RUNX2), dentine sialophosphoprotein (DSPP), dentine matrix acidic phosphoprotein 1 (DMP1), bone gamma-carboxyglutamate protein (BGLAP), and alkaline phosphatase, biomineralization associated (ALPL) gene expression using real-time PCR. Pearson's correlation analysis was used to assess the linear relationships between different genes and the extent of pain, where p<0.05 was considered significant.
Results: The demographic and clinical characteristics of the patients varied according to age, sex, tooth type, clinical diagnosis, pain level, percussion pain response, and palpation pain sensitivity. The expression levels of the RUNX2 and BGLAP genes in the inflamed dental pulp were significantly greater than those in the control samples. Pearson's correlation analysis demonstrated significant positive correlations between the expression of the BMP2 and BGLAP genes and between the RUNX2 and DMP1 genes within inflamed pulp tissues.
Conclusion: Irreversible pulpitis was associated with positive coordination among odontoblastic activities, metabolism, and dentine formation as a compensatory mechanism. Our findings provide information on the molecular pathogenesis of pulpitis, suggesting future treatment approaches. (EEJ-2024-11-182)

Objective: To evaluate the degree of pulp tissue dissolution using a novel irrigant, Dual Rinse HEDP, at different temperatures.
Methods: Fifty standardized pulp tissue samples (1×1×1 mm) were divided into five groups (n=10): Group A, 0.1 mL of NaOCl (5.25%) at 36.8°C (body temperature); Group B, 0.1 mL of NaOCl (5.25%) at 80°C; Group C: 0.1 mL of NaOCl (5.25%) mixed with Dual Rinse HEDP at 36.8°C; Group D, 0.1 mL of NaOCl (5.25%) mixed with Dual Rinse HEDP at 80°C; Control group: 0.1 mL of saline solution at 36.8°C (n=5) and at 80°C (n=5). The dissolution time of the pulp tissue was recorded in seconds and minutes using a high-resolution digital microscope (20xmagnification) and a stopwatch. Results were statistically analysed using one-way ANOVA and Tukey's HSD post hoc test with significant differences among the groups set at p<0.05.
Results: Statistical analysis indicated that NaOCl at 80°C (Group B: 0.369±0.034 min) and Dual Rinse HEDP at 80°C (Group D: 0.377±0.037 min) demonstrated the fastest dissolution time, without any significant difference between them (p>0.05). Samples treated at body temperature showed significantly longer dissolution times (Group A: 6.252±0.277 min; Group C: 6.389±0.410 min), without any significant difference between them (p>0.05). The control group (Group E) exhibited no pulp dissolution, which significantly differed from all other groups (p<0.05). Heating the irrigants to 80°C resulted in a statistically faster dissolution time compared to the groups tested at body temperature (p<0.05), with no significant differences among the groups tested at the same temperature (p>0.05).
Conclusion: The study highlights the critical role of temperature for the dissolution efficacy of both NaOCl and Dual Rinse HEDP and supports the potential use of Dual Rinse HEDP mixed with NaOCl for continuous chelation. (EEJ-2025-02-016)

Objective: This comprehensive study was aimed to compare the effectiveness of QMix and EDTA, activated by different techniques, in removing apical debris and the smear layer.
Methods: The crowns of 180 single-rooted mandibular premolar teeth were removed, and the root canals were shaped up to #X4 using the ProTaper-Next rotary file system. Samples were randomly divided into six main groups according to the activation protocols (n=30). These groups were as follows: Manuel activation with 30G NaviTip needle (MNA), manual dynamic activation with gutta-percha cone (MDA), passive ultrasonic activation (PUA), EndoActivator (EA), XP-Endo Finisher (XP) and Photon Induced Photoacoustic Streaming (PIPS). Each leading group was then divided into three subgroups for the final irrigation solution (distilled water, 17% EDTA and QMix) (n=10). While debris was examined in the randomly selected five roots in each subgroup, the smear layer was examined in the others. A stereomicroscope with x25 magnification was utilised to examine the debris, and the specimens were evaluated using a 4-grade system. To assess the smear layer, scanning electron microscope images were taken at x1000 magnification at the apical third of the root canals and scored using a 5-grade scoring system. The statistical analysis of the data was performed by using the Kruskal-Wallis test (p<0.05).
Results: While XP and PIPS activation techniques were more effective than the other techniques at apical in terms of debris removal when using QMix (p<0.05), there was no statistically significant difference among the activation techniques when utilising EDTA (p>0.05). Regarding the removal of the apical smear layer, EDTA showed similar efficacy with all the tested activation techniques (p>0.05). Additionally, QMix was shown to be more effective when used in combination with MNA and PUA activation methods compared to MDA, EA, XP and PIPS techniques (p<0.05).
Conclusion: EDTA was found to be more effective than QMix in removing apical debris; however, OMix demonstrated its highest effectiveness when utilized with activation systems such as PIPS and XP. In addition, EDTA was found to be more effective than QMix in eliminating the apical smear layer. (EEJ-2024-08-139)

Objective: This study compared the dentinal tubule penetration of NeoSEALER Flo bioceramic sealer using single cone and cold lateral compaction obturation techniques.
Methods: Eighteen extracted single-rooted mandibular premolars were randomly divided into two groups (n=9) according to the obturation technique used. The maximum penetration depth in microns, percentage of penetration depth, and percentage of penetration area of the NeoSEALER Flo bioceramic sealer were assessed using confocal laser scanning microscopy at different root levels; coronal, middle, and apical. Data was statistically analyzed using Kruskal-Wallis's test followed by Dunn's post hoc test with Bonferroni correction and Friedman's test followed by Nemenyi post hoc test with the significance level set at p<0.05.
Results: The single cone obturation technique has shown a statistically significantly higher percentage area of NeoSEALER Flo penetration than the lateral compaction technique at the coronal root level only. Otherwise, both obturation techniques have shown no statistically significant differences in NeoSEALER Flo penetration distance, percentage of penetration distance, and percentage of area penetration at the middle and apical root levels.
Conclusion: The single cone obturation technique can be used with bioceramic sealers yielding comparable results to the cold lateral compaction technique. (EEJ-2024-12-192)

Objective: To evaluate the effectiveness of three rotary file systems on the elimination of Enterococcus faecalis (E. faecalis) biofilms in single-rooted teeth.
Methods: A total of 70 mandibular premolars were included in this study in which 60 root canals were inoculated with E. faecalis. The positive control group (n=5) received bacterial inoculation without mechanical preparation. The negative control group (n=5) was neither infected nor mechanically prepared. The teeth were randomly assigned to 3 experimental groups (n=20 per-group) according to application of the rotary files: Group 1: XP-endo Rise Shaper (FKG, Le Crêt-du-Locle, Switzerland); Group 2: XP-endo Shaper (FKG, Le Crêt-du-Locle, Switzerland); Group 3: ProTaper Gold (Dentsply Sirona, Erlangen, Germany). Samples were collected using paper points before (S1) and after (S2) mechanical preparation. Colony-forming units (CFUs) were used to quantify bacterial loads.
Results: Significant differences in bacterial counts were observed from S1 to S2 in all tested groups (p<0.001). Intergroup comparisons revealed no significant differences between the XP-endo Rise Shaper and XP-endo Shaper groups (p>0.05) and between XP-endo Shaper and ProTaper Gold groups (p>0.05). Significant differences were observed between the XP-endo Rise Shaper and ProTaper Gold groups (p<0.05). The XP-endo Rise shaper group showed the largest reduction in bacterial loads (98.2%), followed by the XP-endo Shaper (96.0%) and ProTaper Gold (93.8%) groups.
Conclusion: All tested rotary files were able to reduce bacteria but the novel single-file system (XP-endo Rise shaper) was superior in reducing bacterial load compared to XP-endo Shaper and the multiple file system (ProTaper Gold). (EEJ-2024-08-133)

Objective: To compare the cyclic fatigue resistance of conventional and heat-treated "replica-like" reciprocating instruments with their original counterparts under single and double curvatures and assess tip size discrepancies against manufacturer-reported values.
Methods: Eighteen instruments were used per group for the study. Two measurements at the instrument's tip were made with a digital calliper. Cyclic fatigue resistance was evaluated under single (60°, 5 mm radius) and double curvatures (60°, 5 mm radius each) in a 37°C water bath. Time to fracture (seconds) was recorded and analysed with appropriate statistical tests (p=0.05).
Results: The tip sizes of all instruments were smaller than the value purported by the manufacturers (0.25 mm) and outside the range of values obtained, with significant differences for all groups (p<0.001). Time to fracture were as follows: Reciproc R25: single curvature: 171.5±38.9, double curvature: 133.4±47.4; Reverso Silver: single curvature: 169.0±104.8, double curvature: 57.8±20.0; Reciproc Blue R25 single curvature: 355.4±86.4, double curvature: 140.5±67.7; Reverso Blue: single curvature: 359.5±102.8, double curvature: 142.9±69.0. Reverso Silver presented with a significantly lower time to fracture overall when compared with the Blue instruments (p=0.002) and with all instruments in double curvatures (p<0.05). In single curvatures, blue files had longer times to fracture (p<0.05). When comparing single versus double curvatures, only Reciproc R25 had no significant differences regarding time to fracture (p=0.54).
Conclusion: The tip sizes of the instrument tested were smaller than what is reported by the manufacturers. The cyclic fatigue resistance of the conventional “replica-like” instrument (Reverso Silver) was significantly lower than the blue "heat-treated" comparators. Double curvature hastened fracture. (EEJ-2024-11-174)

This research assessed the interobserver agreement and precision of the tactile method (TM) during orthograde exploration of the apical terminal portion of permanent teeth with necrotic pulps and open apices. Nine non-vital teeth with incomplete root development from nine patients were included. Two observers analyzed preoperative cone beam computed tomography (CBCT) images to determine the distance between the incisal reference point and the apical terminal portion at four apical measurement points: buccal, lingual, distal, and mesial. The shortest of these points was considered the tomographic working length (TWL) and was used as control group. Subsequently, endodontic access and light chemo-mechanical brushing of the main canals were performed, followed by radiographic working length (RWL) establishment. Two different operators applied the TM using a #25 manual K-file (Dentsply Maillefer, Ballaigues, Switzerland) pre-curved in the tip at a 90° angle. The same four apical measurement points were explored, and the tactile method working length (TMWL) was determined. Interobserver agreement was assessed using Bland-Altman method. Wilcoxon signed-rank test and Student’s t-test were used to analyze the correlation between methods (p≤0.05). The measurements conducted for TM and TWL showed a high level of agreement (0.486 and -0.144 mm, respectively). Compared with the control group (TWL) and TMWL, the RWL showed no significant correlation (<0.001 and 0.0068, respectively). TM demonstrated a reliable level of inter-observer agreement and could prove valuable when treating permanent teeth exhibiting non-vital pulps and open apices, especially in cases with radiographic evidence of external inflammatory apical resorption. (EEJ-2024-11-187)

Endodontic microsurgery (EMS) is a specific treatment modality that targets the root apex of infected teeth that have not been healed by traditional root canal treatments. Recently, the use of advanced three-dimensional (3D) reconstruction technology, such as cone beam computed tomography (CBCT), has improved diagnosis and treatment in dentistry. However, locating the root apex accurately using this technology can be challenging. Also, traditional surgical methods often require significant bone removal which usually results in prolonged surgery and increased risk of trauma and infection. This article introduces the concept of targeted EMS using the 3D-printed surgical guide and a trephine bur to perform single-step osteotomy and root-end resection in complex cases. The surgical guide was designed using a computer-aided planning software to ensure precise angulations and depths of preparation while avoiding critical anatomy regions. The use of the trephine bur enabled efficient and accurate targeted osteotomy regarding the site, angulation, and depth of preparation. This case report describes the use of the 3D-printed guide and the trephine bur to accurately perform EMS of a mandibular first molar with a separated instrument and periapical lesions. (EEJ-2024-03-043)