Objective: Apical surgery is an intervention to treat teeth with persistent or recurrent endodontic infection. The proximity of the mental foramen and mandibular canal may pose a risk of altered sensation when performing surgical interventions in the posterior mandible. The objective of this study was to determine the rate of neurosensory disturbances after apical surgery of mandibular premolars and molars. The secondary objective was to evaluate whether the occurrence of altered sensation correlated with the distances from the apex or the periapical lesion to the relevant anatomical structures.
Methods: The charts of patients treated from September 1999 to December 2015 were retrospectively evaluated if an apical surgery had been performed in mandibular premolars or molars, and a minimum period of 1-year follow-up was documented. Patients with trauma or other surgical interventions in the same hemimandible were excluded. Cases with postsurgical altered sensation were defined as the test group. From the pool of unaffected cases, patients were selected to serve as controls. Two- or three-dimensional radiographs of test and control cases were assessed with regard to the shortest distances from the root apices/lesions to the mental foramen or mandibular canal.
Results: The study population included 243 patients with 249 apical surgeries, of which 12.9% led to postoperative neurosensory disturbances. Sensation returned to normal within 22 days on average. The most frequent findings were hyperesthesia or paresthesia. With regard to the treated type of tooth, second premolars resulted more frequently (22.6%) in altered sensation than the other teeth (11.2 to 13.0%; p=0.310). There were no significant differences when comparing test and control cases regarding the measured distances in radiographs from the apex/lesion to the relevant anatomical structures.
Conclusion: Altered sensation may typically occur following apical surgery in posterior mandibular teeth. However, in all cases of the present study, skin sensitivity in the lip/chin region returned to normal. The clinician must be particularly careful when performing apical surgery of second premolars due to the proximity of the mental foramen. (EEJ-2020-06-134)

Objective: The aim of this study was to compare the success rate of anaesthesia with 3% prilocaine and felypressin (0.03 IU/mL) in maxillary first and second molar teeth with irreversible pulpitis.
Methods: The study population was 159 patients (53 males, 106 females) who had maxillary first or second molar teeth with irreversible pulpitis (84 first molars, 75 second molars). A buccal infiltration of 3% prilocaine with 0.03 IU/mL felypressin was used as the primary anaesthetic technique. In addition to using a categorised pain score, sound, eye movement and body motion were considered signs of anaesthesia efficacy. The data were analysed with independent t and Chi‐square tests. Significance was set at α=0.05.
Results: Overall, the success rate was 56.6% in maxillary molars, 53.6% in maxillary first molars, and 60% in maxillary second molars. There was no statistically significant difference between maxillary first and second molars in terms of anaesthesia success rate (P>0.05). The overall success rate of intraligament supplementary injections was 50%, and intrapulpal supplementary injections was 97.91%. No significant difference was found between maxillary first and second molars in terms of the success rate of the supplemental techniques (P>0.05).
Conclusion: No significant difference was found between maxillary first and second molars in terms of anaesthesia success rate when 3% prilocaine with 0.03 IU/mL felypressin was used as an anaesthetic solution for the infiltration injection. (EEJ-2020-11-265)

Objective: Vascular endothelial growth factor A (VEGFA) and its receptors are essential proteins for the angiogenic activity of dental pulp. Angiogenesis fundamentally provides oxygen and nutrients to cells for root formation and defence mechanisms. The angiogenic potential of dental pulp should be understood and considered for the conservative and regenerative endodontics. The purpose of this research was to measure the VEGFA expression and its receptors such as vascular endothelial growth factor receptors 1, -2 (VEGFR1, VEGFR2) and Neuropilin 1 (NRP1) in human dental pulp from molars with immature and mature apexes.
Methods: VEGFA system mRNAs expressions were assessed in dental pulp obtained from freshly extracted human third molars divided into immature (n=8) and mature (n=8) apexes. RNAs were extracted from the samples. Each sample’s cDNA was synthetized and the target genes VEGFA, VEGFR1, VEGFR2, NRP1 expression profiles obtained by RT2-PCR. Analysis was based on the Student’s t-test comparing the replicate 2-ΔCt values for each gene. P values of <0.05 were considered significant.
Results: In teeth with mature apexes, VEGFA (P=0.0002), NRP1 (P=0.0001), VEGFR1 (P=0.0057) and VEGFR2 (P=0.018259) significantly increased statistically with respect to the immature apexes group.
Conclusion: Within the limitation of the present investigation, it can be concluded that the angiogenic process seems to be a physiological process in the dental pulp due to the studied angiogenic growth factor are expressed in both immature and mature dental pulps. VEGFA and its receptors are expressed significantly higher in mature apex teeth than immature apex teeth. (EEJ-2021-03-052)

Objective: This study sought to analyse the relationship between mandibular posterior teeth and the surrounding anatomical structures.
Methods: A total of 170 CBCT images were examined to obtain measurements regarding the following: buccolingual (BL) and mesiodistal (MD) root thickness at the standard level of resection (3 mm from the apex), the thickness of the overlying buccal and lingual bone at the same level, the proximity of the mandibular canal (MC) to the apices of the mandibular posterior teeth, as well as the horizontal location of the mental foramen (MF).
Results: The BL root width at 3 mm from the apex was the broadest at the mesial roots of the first molars with males: 5.33±0.99 mm and females: 5.16±0.88 mm (mean±SD). The root width was narrowest at the second premolars (males: 3.80±0.83 mm; females: 3.61±0.60 mm). At the same level; the buccal bone was thickest over the distal roots of the second molars (males: 6.92±1.85 mm; females: 6.95±1.95 mm) and thinnest over the first premolars (males: 1.73±0.93 mm; females: 1.49±1.01 mm), while the lingual bone was thickest over the distal roots of the first molars (males: 5.58±1.36 mm; females: 4.52±1.24 mm) and thinnest over the distal roots of the second molars (males: 3.13±1.50 mm; females: 2.60±1.46 mm). The nearest root apices to the MC were the distal roots of the second molars (male: 1.21±1.45 mm; female: 1.75±1.97 mm), while the furthest were the mesial roots of the first molars (male: 4.00±2.39 mm; female: 4.77±2.58 mm). The most common horizontal location of the MF was between the first and second premolars (51.8%). The lingual bone was significantly thinner over both roots of first molars in females (P<0.05).
Conclusion: As the position of the teeth became more posterior, the buccal bone thickness increased, the lingual bone thickness decreased, and the distance to the MC became closer. CBCT analysis provides distortion- and superimposition-free images of the relevant anatomic structures. (EEJ-2021-06-110)

Objective: To compare the shaping ability of the XP-endo Shaper (XPS) system to the ProTaper Next (PTN) system in oval-shaped distal root canals.
Methods: From 12 mandibular molars, distal roots with moderately curved single oval canals were randomly assorted to be instrumented with XPS (experimental group) or PTN (control group) and then scanned using micro-computed tomography [Scan 1]. The root canals of the XPS samples were prepared following the manufacturer's instructions using 15 insertions (XPS15) and rescanned [Scan 2]. An additional 10 insertions to the working length were applied, totalling 25 insertions (XPS25), and the roots were rescanned again [Scan 3]. PTN samples were prepared up to the X3 instrument (PTNX3) and rescanned [Scan 2]. The dentine removed and the unprepared areas were assessed. Data were analysed using a t-test with significance at α=0.05.
Results: XPS25 was associated with a significantly greater dentine removal than XPS15 over the entire root canal length and in all three-thirds of the root canal (P<0.05). XPS25 significantly removed more dentine than PTNX3 in only the coronal third (P<0.05). XPS25 was also associated with a significantly smaller percentage of unprepared areas than XPS15 overall and in the coronal third (P<0.05). PTNX3 was associated with a significantly larger percentage of unprepared areas than XPS15 and XPS25 overall and in the coronal and middle
thirds (P<0.05).
Conclusion: Ten additional movements with XPS significantly improved instrumentation capacity, reducing the percentage of untouched surface areas but also removing more dentine. (EEJ-2021-01-017)

Objective: This study aimed to evaluate the stationary fatigue resistance of three endodontic instrument systems after preparing three root canals with different curvatures and comparing them with unused instruments.
Methods: A total of 60 endodontic files from 3 instrument systems, TruNatomy (TRN), HyFlex CM (HFC) and Revo-S (RS), were selected for this study. These systems were divided into 2 groups: Group I (Used files) and Group II (Unused files). Each group was further divided into 3 subgroups, each containing 10 TRN (#26/v.04), 10 HFC (#25.04) and 10 RS (#25/.04) rotary files. The group I instruments were used for shaping the root canals of extracted third molars, while the group II instruments were not used for canal shaping procedures. Both Group I and Group II instruments were subjected to stationary cyclic fatigue testing at simulated body temperature (37±0.5°C) using a stainless-steel block with an artificial canal. The number of cycles to failure (NCF), the length of fractured instruments and the preparation time were recorded. The statistical analysis was performed using two-way ANOVA and Tukey post-hoc tests with a 95% confidence interval (P=0.05).
Results: NCF was significantly affected by the instrument type and whether the instrument was unused or used (P<0.001). The Group II instruments were more resistant to stationary cyclic fatigue than Group I (P<0.05). HFC instruments were most resistant to stationary fatigue among all tested conditions, followed by TRN and RS instruments. Canal preparation with TRN was significantly faster than with HFC and RS. During preparation, no file was fractured. A statistically significant difference (P<0.05) was observed in the mean length of the fractured instruments among used instrument groups.
Conclusion: The stationary cyclic fatigue resistance of HFC instruments were significantly greater than that of the TRN and RS instruments (P<0.05). TRN was faster in shaping the root canals than other instruments tested in the study. (EEJ-2021-01-09)

Objective: The aim of this study was to evaluate the bending and torsional resistance of the following instruments: Mtwo 25/.07 (MT - VDW, Munich, Germany), Navigator W-XN 25.07 (WXN - Wizard Navigator, Medin, Nové Město na Moravě, Czech Republic), ProTaper Universal SX 19/.04 (PSX - Dentsply Tulsa Dental Specialties, Tulsa, USA), MK Orifice Shapper 17/.08 (OS - MK Life Medical and Dental Products, Porto Alegre, Brazil) and MK Sequence 17.12 (MKS - MK Life Medical and Dental Products, Porto Alegre, Brazil).
Methods: One hundred instruments were used (n=20). Resistance to bending (n=10), torque and angular deflection (n=10) at the failure of new instruments were measured according to ISO 3630-1. Metal mass volume at 3 mm from the tip was evaluated using micro-computed tomography (micro-CT). The fractured surface of each fragment was examined by scanning electron microscopy (SEM). Data were analysed using 1-way analysis of variance and Tukey tests.
Results: Torsional resistance values of MK Sequence were higher than the other groups (P<0.05). No differences were observed among MT, WXN and OS (P>0.05) and PTS, which presented the lowest values (P<0.05). MT showed the highest angular deflection (P<0.05). WXN and PSX presented no significant difference (P>0.05). PSX and OS also showed no significant differences (P>0.05). MKS instruments had the lowest angular deflection values (P<0.05). There were significant differences among all the groups in bending stiffness test (P<0.05), but PSX had the lowest torque to bend (P<0.05). MKS had the larger metal mass volume at 3 mm from the tip (P<0.05). SEM analysis showed similar and typical features of torsional failure for all instruments tested.
Conclusion: In conclusion, MK Sequence 17/.12 had the highest torsional fracture resistance. Mtwo 25/.07 showed higher angular deflection capacity, and ProTaper Universal SX the 19/.04 lower bending stiffness. (EEJ-2020-12-276)

Objective: The purpose of this prospective quantitative study was to assess the improvement of skills among pre-clinical dental students who practiced root canal obturation on a 3D-printed tooth model.
Methods: Preclinical students at the dental school (n=145) enrolled in the 2-week endodontic rotation course were invited to participate in the study. Four alphabetically distributed intact groups of first-year students were randomly allocated to either the control or the experimental group that obturated canals of a 3D-printed tooth. The plastic model was obtained from a microCT scan and based on an STL data set. The model was an identical replica of a natural mandibular molar that had been instrumented, ready for obturation. The control group did not obturate the tooth model but received identical instruction. Later in the course all students obturated an extracted human mandibular molar tooth. Technical obturation quality was assessed by two blinded evaluators. Radiographs were used to evaluate obturation length and density. Inter-observer reliability of average performance scores was calculated with the intra-class correlation coefficient for both consistency and absolute agreement. Obturation skills of those who practiced with the model were statistically compared to students who did not use the model with the Mann-Whitney U-test.
Results: Inter-observer reliability was very high for both consistency and absolute agreement. No significant differences were found in obturation skills between the experimental and control group (P>0.05).
Conclusion: Under the condition of this study, dental students’ obturation skills did not significantly improve by further practicing obturation using a 3D-printed model. (EEJ-2021-05-084)

Objective: The aim of this study was to comparatively evaluate the proliferation, differentiation and mineralization inducing potential of strontium incorporated tetracalcium phosphate cement (STTCP) and mineral trioxide aggregate (MTA) on human dental pulp stem cells (hDPSCs).
Methods: hDPSCs were cultured from freshly extracted human premolar teeth. Cement discs (5mm×3mm) were prepared using MTA and STTCP. hDPSCs were exposed to the test materials and grouped as follows: 1. MTA; 2. STTCP; 3. NC: Media alone (negative control; 4.PC: hDPSCs with osteogenic medium (positive control); Cell viability and proliferation was evaluated using MTT and trypan blue assays for 0, 7 and 14 day intervals. Odontoblastic differentiation potential were evaluated using ALP assay followed by degree of mineralization using Alizarin Red test and Osteopontin expression on day 7,14 and 21. Quantitative analysis were done by evaluating the absorbance and expressed as optical density. Statistical analysis was performed using Kruskal Wallis test followed by Friedman test (P<0.05).
Results: MTA showed higher percentage of cell proliferation than STTCP at day 7 and 14. ALP assay revealed higher significant value for STTCP on day 7 and 14. STTCP exhibited intense staining and similar mineralization potential with MTA at all time periods. Osteopontin expression was exhibited by both MTA and STTCP on all days (P<0.05).
Conclusion: STTCP promoted cell viability and enhanced mineralization and odontogenic differentiation potential on hDPSCs similar to MTA. STTCP has a potential to be an alternative therapeutic agent for pulp capping procedures. (EEJ-2021-03-041)

Objective: This study aimed to assess the cytotoxicity and genotoxicity of triple antibiotic paste, double antibiotic paste and calcium hydroxide medicaments on human stem cells of the apical papilla.
Methods: In this experimental study, stem cells were isolated from the apical papilla and cultured. They are treated with different concentrations 0.1, 0.5, 1, 10 and 100 mg/ml of medicaments for 24, 48 and 72 hours. The cytotoxicity and genotoxicity of the medicaments were determined using methyl thiazolyl tetrazolium assay and Comet test, respectively.
Results: Results showed all tested concentrations of the calcium hydroxide had no significant effect on stem cells at any time point. Triple antibiotic paste showed cytotoxicity in 10 and 100 mg/mL concentrations at all-time points and in 1, 10 and 100 mg/ml concentrations at 72 hours. In addition, its genotoxicity was significantly higher than that of other groups (P<0.05). Double antibiotic paste showed cytotoxic effects only in 100 mg/ml concentration at 24 hours and 10 and 100 mg/ml concentrations at 48 and 72 hours. And also, its genotoxicity in these concentrations was significantly higher than that of control and calcium hydroxide groups (P<0.05).
Conclusion: In contrast to calcium hydroxide, triple antibiotic paste and double antibiotic paste, especially in their higher concentrations, induced cytotoxicity and genotoxicity on human stem cells of the apical papilla. (EEJ-2020-12-289)

Objective: To compare the removal of calcium hydroxide (CaOH) pastes containing N-Methyl-2-pyrrolidone (NMP), lidocaine, glycerine, methylcellulose, or water from artificially created grooves.
Methods: In this study, 115 human single-rooted maxillary incisors with single and straight root canals were prepared using a rotary file up to size 40/.04 and split longitudinally. A longitudinal groove was created from 2 to 5 mm from the apex and filled with CaOH combined with different vehicles. The specimens were divided among 5 experimental groups according to the vehicle as follows: distilled water, lidocaine, glycerine, methylcellulose, and NMP. The two halves were re-attached, and the canals were flushed with 10 ml of 17% EDTA for 60 seconds. The residual amount of CaOH was scored using a stereomicroscope at 8× magnification. Statistical significance was set at P<0.05.
Results: The NMP-based group exhibited significantly less residual medicament compared to the distilled water (P<0.05), while there were no statistically significant differences among the methylcellulose-, lidocaine-, and glycerine-based groups and distilled water (P>0.05).
Conclusion: The vehicle is an important factor in the successful removal of CaOH medicament from the root canals. Within the limitations of the present study, the NMP-based CaOH medicament exhibited better removal efficacy than the distilled water. However, the cleaning success of the methylcellulose-, lidocaine-, and glycerine-based groups was similar to that of distilled water. (EEJ-2021-07-132)

Objective: The aim of this study was to compare the pull-out bond strength of prefabricated titanium posts cemented with novel fast-setting calcium silicate, zinc phosphate, or glass ionomer cements.
Methods: Sixty extracted human maxillary incisors were selected and received root canal treatment. Post space was prepared for titanium ParaPost XP size 5 (diameter=1.25 mm). The posts were cemented using novel calcium silicate cement, zinc phosphate cement, or glass ionomer cement (n=20). Specimens were stored in phosphate-buffered saline for 4 weeks. Subsequently, the posts were subjected to axial tensile force until bond failure. Data were analyzed by one-way ANOVA followed by multiple comparisons.
Results: The posts cemented with novel calcium silicate cement (10.5±3.8 MPa) demonstrated significantly higher bond strength than zinc phosphate (8.0±2.6 MPa) and glass ionomer cements (8.0±2.7 MPa) (P<0.05).
Conclusion: Within the limitation of the study, the pull-out bond strength of titanium post cemented with novel calcium silicate cement in endodontically treated teeth was superior to zinc phosphate and glass ionomer cements. (EEJ-2021-02-036)

Objective: To assess and compare the fracture strength of endodontically treated teeth when the retrograde preparations were restored either with Biodentine or Endosequence BC RRM Fast set putty or Geristore.
Methods: One hundred and twenty human mandibular premolars were used and allocated randomly into five groups (n=24 each). Following conventional root canal treatment, and apical root resection, retrograde cavities of 3 mm were prepared using ultrasonic tips. Group 1 (intact, sound teeth), Group 2 (without rootend filling), Groups 3, 4 and 5were allocated for Biodentine, Endosequence BC RRM putty, and Geristore respectively. Thermo-mechanical cyclic loading (TMC) was performed for one section of samples in each group (n=12 each) following which immediate and after TMC fracture resistance was evaluated using the Instron machine. One-way ANOVA followed by Tukey's multiple post-hoc procedures was used for data analysis.
Results: Intact teeth had shown the highest fracture strength values than all other four groups (P<0.05) and resected roots without root-end filling group exhibited the lowest resistance to fracture. Amongst the test groups, Endosequence BC RRM putty displayed improved fracture strength, and Geristore exhibited the least resistance to fracture. Fracture strength values were not statistically different among Endosequence fast set putty and Biodentine group samples immediately and after thermo-mechanical cyclic loading (P=0.5987 and 0.9999 respectively). The fracture strength was notsignificantly different between Geristore and without root-end filling groups (P=0.3530).
Conclusion: Endodontically treated teeth with Endosequence BC RRM putty or Biodentine root-end filled teeth had shown better fracture resistance compared to Geristore. Retrofilling with Geristore was not able to improve fracture strength of root canal-treated teeth. (EEJ-2021-04-067)