Proof-of-Principle Experiment for Testing Strong-Field Quantum Electrodynamics with Exotic Atoms: High Precision X-Ray Spectroscopy of Muonic Neon.

To test bound-state quantum electrodynamics (BSQED) in the strong-field regime, we have performed high precision x-ray spectroscopy of the 5g-4f and 5f- 4d transitions (BSQED contribution of 2.4 and 5.2 eV, respectively) of muonic neon atoms in the low-pressure gas phase without bound electrons. Muonic atoms have been recently proposed as an alternative to few-electron high-Z ions for BSQED tests by focusing on circular Rydberg states where nuclear contributions are negligibly small. We determined the 5g_{9/2}- 4f_{7/2} transition energy to be 6297.08±0.04(stat)±0.13(syst) eV using superconducting transition-edge sensor microcalorimeters (5.2-5.5 eV FWHM resolution), which agrees well with the most advanced BSQED theoretical prediction of 6297.26 eV.

Deexcitation Dynamics of Muonic Atoms Revealed by High-Precision Spectroscopy of Electronic K X Rays.

We observed electronic K x rays emitted from muonic iron atoms using superconducting transition-edge sensor microcalorimeters. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic Kα and Kß x rays together with the hypersatellite K^{h}α x rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the L-shell electrons, accompanied by electron side feeding. Assisted by a simulation, these data clearly reveal the electronic K- and L-shell hole production and their temporal evolution on the 10-20 fs scale during the muon cascade process.

Autoimmune arthritis deteriorates bone quantity and quality of periarticular bone in a mouse model of rheumatoid arthritis.

This study showed that autoimmune arthritis induces especially severe osteoporosis in the periarticular region adjacent to inflamed joints, suggesting that arthritis increases the fragility fracture risk near inflamed joints, which is frequently observed in patients with RA. INTRODUCTION: Periarticular osteoporosis near inflamed joints is a hallmark of early rheumatoid arthritis (RA). Here we show that rheumatic inflammation deteriorates the bone quality and bone quantity of periarticular bone, thereby decreasing bone strength and toughness in a mouse model of RA. METHODS: Female BALB/c mice and SKG mice, a mutant mouse model of autoimmune arthritis on the BALB/c background, were used. At 12 weeks of age, BALB/c mice underwent either Sham surgery or bilateral ovariectomy (OVX), and SKG mice underwent intraperitoneal injection of mannan to induce arthritis. Eight weeks later, the mice were killed and the femurs and tibias were subjected to micro-computed tomography, Fourier transform infrared (FTIR) spectroscopic imaging, X-ray diffraction, histology, and mechanical testing. RESULTS: SKG mice developed significant trabecular bone loss in both the distal metaphysis of the femur and the lumbar vertebral body, but the extent of the bone loss was more severe in the distal metaphysis. Neither SKG nor OVX mice exhibited changes in the geometry and matrix properties of the diaphysis of the femur, whereas SKG mice, but not OVX mice, did exhibit changes in these properties in the distal metaphysis of the femur. Bone strength and fracture toughness of the distal metaphysis of the tibia adjacent to the inflamed ankle joint were significantly decreased in SKG mice. CONCLUSIONS: Autoimmune arthritis induces periarticular osteoporosis, characterized by deterioration of cortical bone geometry and quality as well as by trabecular bone loss, leading to severe bone fragility in periarticular bone adjacent to inflamed joints.

Efficacy and safety of osteoporosis medications in a rat model of late-stage chronic kidney disease accompanied by secondary hyperparathyroidism and hyperphosphatemia.

This study showed that bisphosphonate was safe and effective for the treatment of bone disorders in stage 4 chronic kidney disease (CKD) rats. Intermittent teriparatide therapy showed an anabolic action on bone even under secondary hyperparathyroidism conditions without having an adverse effect on mineral metabolism in late-stage CKD. INTRODUCTION: Patients with late-stage CKD are at high risk for fragility fractures. However, there are no consensus on the efficacy and safety of osteoporosis medications for patients with late-stage CKD. In the present study, we aimed to examine the efficacy and safety of alendronate (ALN) and teriparatide (TPD) for treating bone disorder in late-stage CKD with pre-existing secondary hyperparathyroidism using a rat model of CKD. METHODS: Male 10-week-old Sprague-Dawley rats were subjected to a 5/6 nephrectomy or sham surgery and randomized into the following four groups: sham, vehicle (saline subcutaneous (sc) daily), ALN (50 µg/kg sc daily), and TPD (40 µg/kg sc daily). Medications commenced at 24 weeks of age and continued for 4 weeks. Micro-computed tomography, histological analysis, infrared spectroscopic imaging, and serum assays were performed. RESULTS: Nephrectomized rats developed hyperphosphatemia, secondary hyperparathyroidism (SHPT), and high creatinine, equivalent to CKD stage 4 in humans. ALN suppressed the bone turnover and increased the degree of mineralization in cortical bone, resulting in an improvement in the mechanical properties. TPD further increased the bone turnover and significantly increased the degree of mineralization, micro-geometry, and bone volume, resulting in a significant improvement in the mechanical properties. Both ALN and TPD had no adverse effect on renal function and mineral metabolism. CONCLUSIONS: BP is safe and effective for the treatment of bone disorders in stage 4 CKD rats. Intermittent TPD therapy showed an anabolic action on bone even under SHPT conditions without having an adverse effect on mineral metabolism in late-stage CKD.

Root surface strain during canal shaping and its influence on apical microcrack development: a preliminary investigation.

AIM: To determine the root surface strain (RSS) generated during root canal shaping and its effects on apical microcrack development. METHODOLOGY: Twenty-five extracted human mandibular premolars were selected and decoronated. The teeth were instrumented with either the ProTaper (PT) or WaveOne (WO) (Dentsply Maillefer) NiTi rotary systems (n = 10 per group) or used as controls (n = 5). Instrumented root canals were enlarged to ProTaper F4 (size 40, 0.06 taper) or using WaveOne LARGE (size 40, 0.08 taper) instruments according to the manufacturer's instructions. An electrical strain gage (KFG02-120-C1-16, Kyowa Dengyo, Tokyo, Japan) was fixed on the proximal root surface and connected to a strain amplifier via a bridge box in order to measure RSS. During canal shaping, the strain output of the amplifier was recorded. The instantaneous RSS induced by each instrument and the maximum RSSs were determined. All teeth were then stained with contrast media and imaged with micro-computed tomography (micro-CT) at an isotropic resolution of 10 µm to detect microcracks. The mean maximum RSS values (microstrain) and mean number of microcracks recorded for both groups were tested for statistical significance using Mann-Whitney U-test. Presence/absence of microcracks in both groups was compared by chi-square tests. RESULTS: Increased baseline RSS from strain accumulation during canal shaping was observed, with similar maximum RSS (mean ± SD) for PT (416.6 ± 185.1 µstrain) and WO (398.2 ± 163.8 µstrain) (P = 0.94). The interevaluator reliability for microcrack detection using micro-CT had a kappa value of 0.998. Compared to the PT group, there was a trend for fewer samples with microcracks in the WO group (P = 0.051). On the micro-CT images, apical microcracks were detected in 20 PT and 11 WO samples (P = 0.10). The microcracks were observed in the buccolingual direction in all WO and 81% of PT samples. No vertical root fractures were found. The maximum RSS obtained during canal shaping was poorly correlated with the number of microcracks found (R(2)  = 0.093). CONCLUSIONS: Based on these preliminary data, canal shaping appears to cause apical microcracks regardless of the type of rotary instrument motion. Contrast-enhanced micro-CT was able to identify microcracks in roots.

Differential diagnosis of vertical root fractures using reconstructed three-dimensional models of bone defects.

OBJECTIVES: The purpose of this study was to evaluate the accuracy of diagnosing vertical root fractures (VRFs) by comparing the volume of bone defects in VRFs with those in non-VRFs on reconstructed three-dimensional (3D) models (TDMs) using CBCT. METHODS: 32 maxillary pre-molars and anterior teeth with radiolucent areas were evaluated on pre-operative CBCT images. Of the 32 teeth, 16 had a fractured root (VRF group) and 16 had a non-fractured root (non-VRF group). The radiolucent area of each tooth was traced in each dimension [mesiodistal, buccolingual and horizontal (the apicoincisal aspect)] by two observers, and 3D images were reconstructed with the Amira(®) software (Visage Imaging Inc., Richmond, Australia). The volume, V, of the TDM was divided into the coronal side and the periapical side at the horizontal slice through the apical foramen, and v was defined as the volume of the coronal side. The values of v/V were calculated for all cases. The Mann-Whitney U test was used to compare values between the VRF group and the non-VRF group (p < 0.05). A receiver operating characteristic (ROC) curve was constructed to select the optimal cut-point. RESULTS: There was a statistically significant difference in the value of v/V between the two groups (p < 0.05). With a cut-point derived from the ROC curve, and the sensitivity, specificity and accuracy of predicting the VRFs were 1.00, 0.75 and 0.88, respectively. CONCLUSIONS: Lesions resulting from VRFs can be distinguished from those of non-VRFs on 3D CBCT images with a high degree of accuracy, based on their different 3D shapes.

The effect of endodontic procedures on apical crack initiation and propagation ex vivo.

AIM: To evaluate the potential effects of endodontic procedures (instrumentation and filling) on crack initiation and propagation in apical dentine. METHODOLOGY: Forty extracted single-rooted premolars with two canals were selected, 1.5 mm of the apex was ground perpendicular to the long axis of the tooth and the surface polished. The specimens were divided into 4 groups. The buccal canals of groups A, B and C were enlarged to size 40 with manual K-files. Group A was filled with gutta-percha using lateral condensation and vertical compaction without sealer. Group B was filled with the same method as group A except only lateral condensation was used. Group C was left unfilled, while group D was left unprepared and unfilled. Images of the resected surface were taken after resection (baseline), after canal preparation, after filling and after 4-week storage. The images were then inspected for cracks originating from the canal. RESULTS: A significant effect of preparation on crack initiation (P < 0.05) and no significant effect of filling (P > 0.05) or 4-week storage on crack initiation (P > 0.05) was found (logistic regression). Fisher's exact test revealed a significant effect of filling on crack propagation (P < 0.05) and no effect of 4-week storage on crack propagation (P > 0.05). CONCLUSIONS: Root canal procedures can potentially initiate and propagate cracks from within the root canal in the apical region.

Odontoblastic syncytium through electrical coupling in the human dental pulp.

We have previously reported a dye-coupling network between odontoblasts (OBs). However, it is still unclear how the information detected by the odontoblasts is transmitted. The aim of this study was to characterize the odontoblastic syncytium electrophysiologically in the human dental pulp. Pulpal cells were freshly isolated from human premolars immediately after extraction. Under a light microscope, coupled or small clusters (3-20) of odontoblasts, each of which had a monopolar process (95-280 µm) and an oval cell body, were easily observed to be lined up in parallel. Cells were used for electrophysiological recording within 3 hrs in the dual patch-clamp configuration. Electrical couplings were found between odontoblasts (37/40 pairs). Voltage gating showed directional independence between pairs of odontoblasts. The time constant to a current decay increased with the number of clustered odontoblasts. Nine of 37 pairs isolated from young patients were electrically coupled, but could not be voltage-clamped. Transjunctional currents were blocked by octanol. These results suggest that odontoblasts form a syncytium that is directionally independent via symmetric gap junction channels in the odontoblastic layer. Young odontoblasts with a high electrical conductance to neighboring cells may be related to high potential of information transmission or calcification.

Nano-indentation testing of new and fractured nickel-titanium endodontic instruments.

AIM: To investigate the effect of cyclic fatigue on nickel-titanium (NiTi) endodontic instruments using a nano-indentation test. METHODOLOGY: Eight ProFile NiTi rotary instruments (size 30, taper 0.06; Dentsply Maillefer, Ballaigues, Switzerland) were tested using a cyclic fatigue set-up until fracture. The fractured instruments and eight new NiTi instruments of the same size and taper were used for a nano-indentation test on the internal surfaces of a NiTi instruments in the region just adjacent to their fractured edge (group I) and in the same region of the new group (group II), and the cutting part beside the shaft for both instruments [group III (fractured) and group IV (new)]. Data were statistically analyzed using one-way analysis of variance and Games-Howell post hoc test. The alpha-type error was set at 0.05. RESULTS: Significant differences in terms of hardness and elastic modulus for each group (P < 0.05) were found, with group I having the lowest mean values followed by group III. Additionally, standard deviations increased remarkably after failure, as represented by groups I and III. CONCLUSION: The nano-indentation technique can be applied to determine the performance and the failure mechanism of NiTi instruments. The fatigue process revealed a significant decrease in the hardness and elastic modulus of the NiTi instrument. As indicated by the low hardness, the fatigue process did not result in work hardening but rather work softening.

Coexistence of fibrotic and chondrogenic process in the capsule of idiopathic frozen shoulders.

OBJECTIVE: To analyze changes in the capsule from idiopathic frozen shoulders and clarify their etiology. MATERIALS AND METHODS: Samples (the rotator interval capsule, middle glenohumeral ligament (MGHL), and inferior glenohumeral ligament (IGHL)) were collected from 12 idiopathic frozen shoulders with severe stiffness and 18 shoulders with rotator cuff tears as a control. The number of cells was counted and the tissue elasticity of the samples was calculated by scanning acoustic microscopy (SAM). The amount of glycosaminoglycan content was assessed by alcian blue staining. Gene and protein expressions related to fibrosis, inflammation, and chondrogenesis were analyzed by quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC). Furthermore, the total genes of the two groups were compared by DNA microarray analysis. RESULTS: The number of cells was significantly higher and the capsular tissue was significantly stiffer in idiopathic frozen shoulders compared with shoulders with rotator cuff tears. Staining intensity of alcian blue was significantly stronger in idiopathic frozen shoulders. Gene expressions related to fibrosis, inflammation, and chondrogenesis were significantly higher in idiopathic frozen shoulders compared with shoulders with rotator cuff tears assessed by both qPCR and DNA microarray analysis. CONCLUSION: In addition to fibrosis and inflammation, which used to be considered the main pathology of frozen shoulders, chondrogenesis is likely to have a critical role in pathogenesis of idiopathic frozen shoulders.

Initial fibroblast attachment to Erbium:YAG laser-irradiated dentine.

AIMS: To evaluate the effects of Erbium (Er):YAG laser irradiation on the morphology of resected dentine surfaces, and to investigate fibroblast attachment to laser-irradiated dentine surfaces. METHODOLOGY: Dentine blocks obtained from single-rooted human teeth were divided into the following groups after sterilization in an autoclave: (i) Laser group treated with Er:YAG laser irradiation (30 mJ per pulse, 10 pps, 60 s); (ii) L-MTAD group treated with laser irradiation as in (i) plus a mixture of doxycycline, tetracycline isomer and citric acid; (iii) RC-Prep group treated with EDTA gel or cream (RC-Prep) and (iv) Control group left untreated. After each treatment, the dentine blocks were incubated with NIH/3T3 fibroblasts cultured to subconfluency in Dulbecco's modified Eagle's medium supplemented with 10% foetal bovine serum and antibiotics. The number of attached cells amongst the groups was analysed statistically at the 5% significance level. The dentine surface morphologies and cell attachments were evaluated by counting assays, histological observations and scanning electron microscopy (SEM). RESULTS: The number of attached cells was significantly higher (P < 0.05) in the Laser group than in the RC-Prep and Control groups at 16 h. Dendritic cell extension of the fibroblasts was only observed in the Laser group at 8 h by SEM. In the histological analyses, significantly more attached cells were found on the dentine surfaces treated with laser irradiation. CONCLUSIONS: Er:YAG laser irradiation induced morphological alterations in dentine surfaces, which may improve the attachment of fibroblasts to dentine.

Heat treatment of nickel-titanium rotary endodontic instruments: effects on bending properties and shaping abilities.

AIM: To evaluate the bending properties and shaping abilities of nickel-titanium endodontic instruments processed by heat treatment. METHODOLOGY: K3 files were heated for 30 min at 400 °C (group 400), 450 °C (group 450) and 500 °C (group 500). Files that were not heat treated served as controls. A cantilever-bending test was used to evaluate changes in specimen flexibility caused by heat treatment. Curved root canal models were prepared. The times required for preparation, deformation and fracture were recorded. Pre- and postoperative images were superimposed. The amounts of resin removed from both the inner and the outer sides of the curvature in the apical 6 mm were determined. RESULTS: In the cantilever-bending test, load values of the control group and group 500 were higher than those of groups 400 and 450 at the elastic range (P<0.05). At the superelastic range, the bending load of the control group was the highest amongst all groups (P<0.05). Regarding shaping ability, in the control group, root canals at the apex were transported more to the outer side of the curvature compared with those of all heat-treated groups (P<0.05). Root canals of group 400 at 3 mm from the apex were transported less compared with those of other groups (P<0.05). No significant difference was found in working time amongst the groups. In group 450, there was no plastic deformation or fracture of the file. CONCLUSIONS: Heat treatment of files might improve their flexibility, making them more effective for preparation of curved canals.

Phase transformation behaviour and bending property of twisted nickel-titanium endodontic instruments.

AIM: To investigate the relationship between phase transformation behaviour and bending property of nickel-titanium endodontic instruments manufactured by a twisting process. METHODOLOGY: The phase transformation behaviour and bending property of Twisted Files (TF; SybronEndo, Orange, CA, USA) and K3 (SybronEndo) with.06 taper and size 30 tip were investigated. K3 was used as control group. Phase transformation behaviour was estimated by differential scanning calorimetry (DSC). Transformation temperatures were calculated from the DSC curve. Bending load of the instruments was measured by cantilever-bending test at 37°C. Data were analysed by Student's t-test and Mann-Whitney U-test. RESULTS: The phase transformation temperatures of TF were significantly higher (P<0.05) than those of K3. The bending load values were significantly lower for TF than that of K3 (P<0.05), both in the elastic and super-elastic ranges. CONCLUSIONS: The new method of manufacturing NiTi instruments by twisting coupled with heat treatment might contribute to the increased phase transformation temperatures and superior flexibility.

MEPE activated by furin promotes pulpal cell adhesion.

UNLABELLED: Matrix extracellular phosphoglycoprotein (MEPE) is predominantly expressed in osteoblasts, osteocytes, and odontoblasts and plays key biological roles in bone and dentin metabolism. Post-translational modifications are essential for its activation. This study tested the hypothesis that MEPE is activated through proteolytic processing by furin in dental pulp. MEPE was present in three sizes, 1 full-length and 2 cleaved fragments; the cleavage site was 146R↓147. The proprotein convertase family, particularly furin, was a candidate enzyme. Introducing a substitution at the cleavage site inhibited hydrolysis, but there was no cleavage of MEPE expressed in furin-deficient LoVo cells. Therefore, furin is a strong candidate for the proteolytic cleavage of MEPE. The C-terminal cleavage product promoted cell adhesion via its RGD motif. These results indicate that proteolytic processing by furin may activate MEPE during its secretion from odontoblasts and may play important roles in dentinogenesis and pulpal homeostasis. ABBREVIATIONS: MEPE, matrix extracellular phosphoglycoprotein; PTM, post-translational modifications; OLC, odontoblast-lineage cells.

Periapical bone defects of root filled teeth with persistent lesions evaluated by cone-beam computed tomography.

AIM: To evaluate and categorize the bone defects of root filled teeth with persistent periapical lesions by cone-beam computed tomography (CBCT). METHODOLOGY: Slice images of 532 teeth with persistent periapical lesions were obtained by CBCT in 427 patients and were examined by two endodontists. The periapical lesions were categorized into five types according to the characteristics of the bone defect based on CBCT images. The prevalence of each type was determined and analysed statistically at a 5% significance level using logistic regression. RESULTS: Of the 532 teeth analysed, 67% had buccal or labial bone plate defects (type II), 4% palatal or lingual bone plate defects (type III), 7%'through and through' defects (type IV) and 10% apical root protrusions from the bone plate (type V). Mandibular teeth had a significantly greater prevalence of type I lesions (P=0.0005) and a significantly lower prevalence for types IV (P=0.041), V (P=0.001), V-1 (P=0.015) and V-2 (P<0.001) as compared to maxillary teeth. CONCLUSION: CBCT accurately identified the type of periapical bone defect in persistent lesions. Because 10% of the teeth had apical root protrusions, which could not be identified by periapical radiography, the diagnostic information obtained by CBCT was an essential component of the treatment planning process.

Neuron-immune interactions in the sensitized thalamus induced by mustard oil application to rat molar pulp.

We have reported that mustard oil application to the rat dental pulp induces neuronal activation in the thalamus. To address the mechanisms involved in the thalamic changes, we performed neuronal responsiveness recording, immunohistochemistry, and molecular biological analysis. After mustard oil application, neuronal responsiveness was increased in the mediodorsal nucleus. When MK801 (an N-methyl-D-aspartate receptor antagonist) was applied to the mediodorsal nucleus, the enhanced responsiveness was decreased. N-methyl-D-aspartate receptor 2D, glial fibrillary acidic protein, and antigen-presenting cell-related gene mRNAs in the contralateral thalamus were up-regulated at 10 minutes after mustard oil application, but were down-regulated within 10 minutes after the antagonist application. OX6-expressing microglia and glial fibrillary acidic protein-expressing astrocytes did not increase until 60 minutes after mustard oil application. These results suggested that the thalamic neurons play some roles in regulating the glial cell activation in the mediodorsal nucleus via N-methyl-D-aspartate receptor 2D during pulp inflammation-induced central sensitization.

Incidence of accessory canals in Japanese anterior maxillary teeth following root canal filling ex vivo.

AIM: To investigate the vertical and horizontal distribution and the incidence of accessory canals in Japanese maxillary anterior teeth following root filling. METHODOLOGY: The study included maxillary teeth; 69 central incisors, 61 lateral incisors and 31 canines. After the canal systems had been dyed and root canal instrumentation had been carried out, all prepared canals were filled with gutta-percha without using sealer. Transparent specimens were then obtained and examined with a digital microscope for horizontal and vertical distributions of accessory canals. RESULTS: The incidence of teeth with accessory canals in the apical 3 mm was 46%, 29% and 38% for the maxillary central incisors, lateral incisors and canines, respectively. The horizontal distribution was mainly buccal for central incisors, palatal for lateral incisors and distal and palatal for canines. There was a significant difference (P < 0.05) between the apical 3 mm and the rest of the root (16%, 20% and 19% for the maxillary central incisors, lateral incisors and canines, respectively) in terms of the presence of accessory canals. CONCLUSIONS: A high percentage of accessory canals can be found in apical 3 mm of the root. The horizontal distribution of accessory canals differed amongst the tooth types studied.

The effect of working length and root canal preparation technique on crack development in the apical root canal wall.

AIM: To evaluate the effects of working length and root canal preparation technique on crack development in the apical root canal wall. METHODOLOGY: Seventy extracted mandibular premolars were mounted in a resin block with simulated periodontal ligaments and divided into seven groups according to preparation technique and working length: group A, step-back preparation with stainless steel files with working length set at the apical foramen and defined as root canal length (CL); group B, same as for A, except that the working length was CL-1 mm; group C, crown-down preparation with Profile instruments followed by an apical enlargement sequence with CL as working length and group D, same as for C, except that the working length was CL-1 mm. Groups E, F and G served as controls. Groups E and F were prepared only with the crown-down sequence up to CL and CL-1 mm, respectively. Group G was left unprepared. Digital images of the apical root surface (AS) were recorded before preparation, immediately after instrumentation and after removing the apical 1 mm (AS-1 mm) and 2 mm (AS-2 mm) of the root end. RESULTS: Working length significantly affected crack development at AS (P < 0.05). Preparation technique significantly affected crack development at AS-1 mm (P < 0.05). At AS-2 mm, there was no significant difference between preparation technique and working length in terms of crack development on the canal wall. CONCLUSION: Root canal preparation alone, regardless of the technique used, can potentially generate cracks on the apical root canal wall as well as the apical surface. Working 1- mm short of the apical foramen might produce fewer cracks in the apical region.

Distance from file tip to the major apical foramen in relation to the numeric meter reading on the display of three different electronic apex locators.

AIM: To establish and compare the relationship between the distance from the file tip to the apical foramen and the numeric meter reading on the display of three different electronic apex locators (EALs). METHODOLOGY: A total of 12 extracted intact, straight, single-rooted human teeth with complete roots were used. The actual root canal length (AL) was determined after access preparation. For the electronic measurements with each EAL, silicon stops were fixed with auto-polymerizing resin to size 15 K-files at AL and 0.5, 1, 2, 3, 4 mm short of AL. The data was analysed by two-way anova and Tukey's honestly significant difference (HSD) test for multiple comparisons amongst EALs. Additionally, one-way anova and Tukey's HSD test were carried out for multiple comparisons amongst the measurements of each EAL. RESULTS: There was a statistically significant difference amongst all EALs in indicating the position of file tips in relation to the major foramen (P < 0.05). The correlation between the meter reading and the position of the file tip from the apical foramen was statistically significant in the three EALs. There were significant differences amongst the measurements at distances from 0 to 2 mm in Justy III. In Dentaport, significant differences were found from 0 to 1 mm. However, the E-Magic Finder showed significant differences from 0 to 0.5 mm. CONCLUSIONS: Justy III was more capable of displaying the intracanal position of the file tip from the major foramen in mm whilst advancing through the root canal during electronic measurements than the Dentaport and E-Magic Finder Deluxe.