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Background and Aim: Complete obturation of the prepared root canal is an essential step in endodontic treatment. Combination of gutta-percha and a sealer is widely used in clinical practice for root canal obturation, thus microleakage studies on sealing properties of these materials constitute an important part of endodontic researches. The aim of this study was to evaluate the microleakage of three root canal sealers: Apexit, AH26 and Dorifill by electrochemical method.Materials and Methods: In this experimental study, 55 extracted human maxillary and mandibular cuspids were used. The coronal part of teeth were removed and the root canals were prepared using the step-back technique. The specimens were randomly divided into 3 groups of 17 samples each. Teeth in each group were filled with one of the sealers and gutta-percha by lateral condensation technique. 4 specimens served as positive and negative controls. An electrochemical method was used for evaluation of apical leakage with the electrical source potential of 10 V. Measurements of current flow through the test system were recorded every 72 hours. Data were analyzed by Kruskall Wallis and Mann Whitney tests. P

Background and Aim: Recent advances in technology have permitted manufacturers to produce endodontic files from NiTi alloy and rotary systems. According to manufacturers, these files maintain original canal shape better than hand files and reduce treatment time. The aim of this study was to compare a new rotary system (Race) with an older one (Profile) in maintaining the original shape of curved canal and the working length as well as the procedural accidents rate. Materials and Methods: In this experimental study, 40 polyester blocks with curved canals (45 ), were fabricated and divided into 2 groups. After primary working length determination and staining with methylene blue, photographs were taken. Canal preparation was done with Profile and Race rotary systems according to manufacturers and working length was measured again. Canal staining by eosin was performed and photographs were taken for the second time. The two images were superimposed and changes in canals anatomy in 5 sections were recorded. Data were analyzed by t test with p 0.05). Changes in working lengths and procedural accidents were similar in the studied groups (P> 0.05). Conclusion: Based on the results of this study, changes in canal anatomy and working length of simulated severely curved canals as well as procedural accidents rate are similar in two rotary systems and both are suitable for canal preparation.

The purpose of this article was reviewing the literature related to the mutual effects of endodontics and orthodontics on each other providing documented information that can be used by dentists in clinical practice. The effect of orthodontic treatment on the dental pulp and its role in root resorption, the influence of previous trauma to the tooth and endodontic treatment in orthodontic tooth movements and root resorption, recommendations regarding endodontic treatment during orthodontic tooth movement and the role of the orthodontic forces in provision and outcome of endodontic treatment are being discussed. The effect of the orthodontic tooth movement on the pulp is focused primarily on the neurovascular system which can cause degenerative and/or inflammatory responses in the dental pulp. Although, most of these changes are considered reversible, it seems that teeth with complete apical foramen and teeth subjected to previous insults, such as trauma, caries, restorations and periodontal diseases are more susceptible to pulpal irreversible changes. Teeth with root canal treatment that are well cleaned shaped, and three- dimensionally obturated, exhibit less propensity to apical root resorption during orthodontic tooth movement. This outcome depends on the absence of microleakage for bacterial ingress. A traumatized tooth can be moved orthodontically with minimal risk of resorption, provided that the pulp has not been severely injured (infection or necrosis). If there is evidence of pulpal demise, appropriate endodontic treatment is necessary prior to orthodontic treatment .If a previously traumatized tooth exhibits resorption, there is a greater chance that orthodontic tooth movement will enhance the resorptive process. If a tooth has been severely traumatized (intrusion, avulsion) there would be a greater incidence of resorption with tooth movement. It is recommended that teeth requiring root canal treatment during orthodontic movement be initially cleaned and shaped followed by the interim placement of calcium hydroxide. Final canal obturation with gutta-percha should be accomplished upon the completion of orthodontic treatment. Endodontically treated teeth can be moved orthodontically similar to teeth with vital pulps. In case of endodontic procedures like apexification, there may be no need to delay the orthodontic treatment.

During the human gestation period, various systemic alterations occur in the mother"nsecondary to endocrine changes. These changes, combined with the presence of the gravid uterus, result"nin conditions affecting the various systems of the mother which must be considered by the dentist."nFetal development is divided into three stages:"n1) The fertilization and implantation period"n2) The embryonic period and"n3) The fetal period."nThe second period characterized by organogenesis which taratogens may result in functional and"nmorphogenic malformations."nThe ideal dental treatment schedule for the pregnant patient is twice during first trimester, at least once"nduring second trimester and once during third trimester."nThe second trimester is an ideal time for performing dental treatment."nEmergency problem should be alleviated immediately during pregnancy."nIndicated medications should not be with held because of pregnancy but patients must be informed of"nbenefits and risks."nWith careful attention to the special needs of the pregnant patient, the dentist can provide high quality"ndental care while minimizing potential risks to mother and fetus."nEmphasis should be on preventive strategies and meticulous oral hygiene to manage common oral"nproblems associated with pregnancy.

Background: The aim of this study was to investigate the effects of retro-cavity preconditioning with or without 17% ethylenediaminetetraacetic acid (EDTA) solution on root surface pH as well as dislodgement resistance of NeoMTA2 and MTA Flow retro-fills. Methods: Forty-eight single-rooted human incisors were selected. After completion of endodontic treatment, root-end resections were performed, and retro-cavities were prepared. The samples were randomly divided into two groups of A and B ( n = 24 each). In group A, retro-cavities were preconditioned with 2.5% NaOCl, followed by 17% EDTA solution, whereas in group B, preconditioning was performed using 2.5% NaOCl before final irrigation with normal saline. Samples in each group were randomly subdivided into two subgroups of 1 and 2. Retro-fillings in the A1 and B1 subgroups were performed with MTA Flow, and in the A2 and B2 subgroups, they were performed with NeoMTA2. Root surface pH was measured in each sample at three different stages: before preparation of retro-cavities (pH0), after retro-cavity preconditioning (pH1), and three days after retro-filling (pH2). Subsequently, the push-out bond strength (PBS) of the retro-filling materials was measured by a universal testing machine, and their failure modes were visualized under 64× magnification. Results: Preconditioning with EDTA caused a significant increase in PBS for both NeoMTA2 and MTA Flow ( p < 0.001). There was no significant difference between the average bond strength of MTA Flow and Neo MTA2 ( p = 0.271). There was a significant increase in the average pH2 compared to pH1 and pH0 across all groups ( p < 0.001). Specifically, the use of EDTA led to a notable increase in the average pH2 in the MTA Flow group compared to the Neo MTA2 group ( p = 0.027). Groups preconditioned with EDTA more frequently indicated a cohesive failure mode. Conclusions: The use of EDTA significantly increased the push-out bond strength of retro-fill materials to dentin. However, it did not prevent the ultimate alkalinity of retro-filled cavities.

Objectives: Antibacterial activity against endodontic pathogens is a desirable feature for root canal sealers. The objective of this study was to compare the antibacterial effect of three resin-based endodontic sealers (AH26, Adseal, and Beta RCS) against Enterococcus faecalis in vitro. Materials and Methods: The antibacterial properties of the sealers were assessed against E. faecalis using agar diffusion test (ADT) for fresh state (N=10) and direct contact test (DCT) for freshly-mixed and set states of the materials (N=10). In ADT, the diameter of the zones of inhibition was measured after 24h of contact. In DCT, the colony-forming units of the bacteria were counted after 30 minutes and 180 minutes of exposure. The results were analyzed with two-way ANOVA and independent sample t-test. P<0.05 was considered significant. Results: Regarding DCT results, all test materials indicated an antibacterial effect, both in freshly-mixed and set states. The highest antibacterial effect was related to Adseal, whereas the lowest was observed in Beta RCS. There was a significant difference between all study groups (different sealers, setting states, and contact times; P<0.001), except for freshly-mixed AH26 and Adseal at 180 minutes (P>0.05). According to ADT, AH26 and Adseal represented the widest and the smallest inhibition zones, respectively (P<0.001). Conclusion: Within the limitations of this in vitro study, AH26, Adseal, and Beta RCS showed antibacterial effects against E. faecalis in both freshly-mixed and set states. The antibacterial effect increased over time in all of the studied sealers., Competing Interests: None declared., (Copyright © 2024 The Authors. Published by Tehran University of Medical Sciences.)

Background: Biocompatibility and induction of mineralized tissue formation are the properties expected from a material used in vital pulp therapy and repair of perforations. Cold ceramic (SJM, Iran; CC) is a newly introduced calcium silicate-based cement for above mentioned therapeutic applications. This in-vitro study aimed to compare the effect of CC and White MTA-Angelus (MTA) on cell viability, attachment, odontogenic differentiation, and calcification potential of human dental pulp stem cells (DPSCs) and periodontal ligament fibroblasts (PDLFs)., Methods: Cell viability of DPSCs and PDLFs was assessed using MTT on days 1, 3, 7, and 14 (n = 9) in contact with freshly mixed and set states of CC and MTA. Field emission scanning electron micrographs (FESEM) were taken to evaluate cell-bioceramic interaction (n = 6). Gene expression levels of osteo/odontogenic markers (Dentin sialophosphoprotein, Dentin matrix protein 1, Collagen type I alpha 1, and Alkaline phosphatase (DSPP, DMP1, COL 1A1, and ALP, respectively) (n = 8) were assessed using qrt-PCR. ALP enzymatic activity was evaluated to assess the mineralization potential. A two-way ANOVA test was applied, and p < 0.05 was considered to be statistically significant., Results: The effect of freshly mixed and set MTA and CC on the survival of DPSCs and PDLFs in all study groups was statistically similar and comparable to the positive control group (p > 0.05); the only exception was for the viability of PDLFs in contact with freshly mixed cements on day 1, showing a more significant cytotoxic effect compared to the control and the set state of materials (p < 0.05). PDLFs attached well on CC and MTA. The spread and pseudopodium formation of the cells increased on both samples from day 1 to day 14. Contact of MTA and CC with DPSCs similarly increased expression of all dentinogenesis markers studied on days 7 and 14 compared to the control group (p < 0.001), except for DSPP expression on day 7 (p = 0.46 and p = 0.99 for MTA and CC, respectively)., Conclusions: Within the limitation of this in-vitro study, cold ceramic and MTA-Angelus showed high biocompatibility and induced increased expression of osteo/dentinogenic markers. Therefore, cold ceramic can be a suitable material for vital pulp therapy and the repair of root perforations., (© 2021. The Author(s).)

Objective . This study aimed to colorimetric comparison of internal bleaching with and without removing mineral trioxide aggregate (MTA) on induced coronal tooth discoloration by MTA cement. In this experimental study, twenty human teeth were prepared. An OrthoMTA barrier was placed 1 mm below the CEJ. The teeth were restored with composite resin and were placed in the aging accelerator machine. Then, the specimens were divided into two groups ( n  = 10); in group A, part of the OrthoMTA was removed and the glass ionomer was placed on the OrthoMTA, and in group B, the OrthoMTA remained intact. Internal bleaching was performed 5 times in 6-day intervals using 37% carbamide peroxide gel. Color determination was performed in 5 stages: baseline, after OrthoMTA discoloration, before OrthoMTA removal, after OrthoMTA removal, and after bleaching treatment sessions. In group A, 8 specimens reached to ∆ E  < 3.3 after 2 times internal bleaching treatment, and in group B, 5 specimens reached to ∆ E  < 3.3 with almost 3 bleaching sessions ( p > 0.05). Additionally, 5 specimens reached to the initial color (baseline) after bleaching treatment, 4 specimens in group A and 1 specimen in group B. After OrthoMTA removal, 2 specimens in group A reached to ∆ E  < 3.3. There was no significant difference between groups with or without OrthoMTA removal ( p =0.06). Although, the specimens with OrthoMTA removal required fewer bleaching treatment sessions, and the mean value of ∆ E was lower in this group., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2021 Sedigheh Khedmat et al.)

Background: This study aimed to assess the effect of ultrasonic activation of photosensitizer on the efficacy of Antimicrobial Photodynamic Therapy (aPDT) against Enterococcus faecalis and penetration depth of photosensitizer., Materials and Methods: In this ex vivo study, mature microbial biofilm of E. faecalis was formed in the root canals of 58 single-rooted single-canal mandibular incisors following their decoronation. The roots were longitudinally sectioned by a diamond disc and split into halves by a chisel. The E. faecalis biofilm was quantified and the penetration depth of photosensitizer was determined by the microbial viability assay and stereomicroscopic analysis in the following three study groups: (1) Ultrasonically activated 5.25% sodium hypochlorite (NaOCl) for 20 s, (2) aPDT using methylene blue (MB) plus 660 nm diode laser with 150 mW power for 1 minute, and (3) ultrasonically activated MB for 20 s followed by aPDT as in group 2. Independent sample t test and one way ANOVA were used to compare the dye penetration depth and microbial load, respectively in the apical and coronal regions among the groups., Results: The penetration depth of photosensitizer in group 3 was significantly greater than that in group 2 (P < 0.05). The E. faecalis count in all three experimental groups was significantly lower than that in the control group (P < 0.05). Groups 1 and 3 were significantly superior to group 2 in terms of reduction in microbial count but the difference between groups 1 and 3 was not significant (P > 0.05)., Conclusion: Ultrasonic activation of photosensitizer in aPDT increases the penetration depth of photosensitizer into the dentinal tubules and enhances its antibacterial activity., Highlight: Ultrasonic activation of photosensitizer in aPDT enhances its penetration depth into dentinal tubules and increases antibacterial efficacy. There was no significant difference between antibacterial effects of aPDT + ultrasonic and ultrasonic activated NaOCl., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objectives: The aim of this study was to assess the antibacterial activities of OrthoMTA, RetroMTA, and ProRoot MTA against Fusobacterium nucleatum ( Fn ), Porphyromonas gingivalis ( Pg ), and Prevotella intermedia ( Pi ) ., Materials and Methods: Each material was mixed on a glass slab using a spatula and was placed in columns containing the filter membrane of the modified membrane-enclosed immersion test (MEIT) system. The materials were sterilized after setting. The columns containing the sterilized test materials were placed in microcentrifuge tubes containing 500 μl of bacterial suspension. The systems were then incubated at 37°C under anaerobic conditions. After 72 hours, the bacterial growth and concentration (colony-forming unit (CFU)/ml) were assessed. The results were analyzed using one-way analysis of variance (ANOVA) and Tukey's post-hoc test in SPSS 22 software. In all analyses, the differences were considered significant at P<0.05., Results: OrthoMTA had the highest antibacterial activity against Pi . The mean number of CFU/ml of Fn in the presence of ProRoot MTA and RetroMTA was significantly lower than that in positive controls. There were significant differences between the antibacterial activities of ProRoot MTA and OrthoMTA against Pg compared to positive controls ., Conclusions: ProRoot MTA, OrthoMTA, and RetroMTA had similar antibacterial activities against the three evaluated anaerobic endodontic bacteria, except RetroMTA against Pg .

Introduction: Reducing the bacterial count from the root canal system is one of the main stages in root canal treatment. The aim of the present clinical study was to compare the antibacterial effect of four intracanal irrigants in primary endodontic infections using both microbiological culture and quantitative Real-time Polymerase Chain Reaction (qRT-PCR) technique., Methods and Materials: Forty patients with primarily infected single rooted premolars were selected and then randomly divided into 4 groups according to the intra canal irrigant used: 5.25% Sodium hypochlorite (NaOCl), Hypoclean (Ogna Laboratori Farmaceutici, Muggiò, Italy), 2% chlorhexidine glouconate (CHX) and CHX-Plus (Vista Dental Products, Racine, WI, USA). Samples were collected before and after chemomechanical preparation and were evaluated by bacterial culture and RT-PCR technique for Enterococcus faecalis and Fusobacterium nucleatum . Data analyzed by repeated measured ANOVA. The significance level was set at 0.05., Results: Four irrigation solutions significantly reduced the total numbers of cultivable bacteria ( P <0.05). No statistically differences were found among the antibacterial effects of 5.25% NaOCl (99.93%), Hypoclean (99.94%), 2% CHX (99.77%) and CHX-Plus (99.83%) in reducing cultivable bacteria. Enterococcus faecalis and Fusobacterium nucleatum were no longer detected after preparation using four irrigants (100% reduction)., Conclusions: All tested irrigants including 5.25% NaOCl, Hypoclean, 2% CHX and CHX-Plus significantly reduced the number of bacterial colonies in primary endodontic infections., Competing Interests: ‘None declared’., (© The Author(s).)

Introduction: The aim of this in vitro study was to compare the efficacy of ProTaper retreatment (ProTaper R) and Mtwo retreatment (Mtwo R) files in removing gutta-percha and GuttaFlow from endodontically treated straight root canals., Methods and Materials: The root canals of 60 human mandibular single-rooted premolars were prepared and randomly divided into two groups (n=30). In groups A and B the root canals were obturated using lateral condensation of gutta-percha plus AH 26 and GuttaFlow, respectively. The canal orifices were temporarily sealed and the roots were incubated for 3 months at 37(º)C and 100% humidity. Primary cone-beam computed tomography (CBCT) images were taken after incubation period. The specimens in each group were randomly divided into two subgroups (n=15). ProTaper R files (D1, D2, and D3) were used in groups A1 and B1 while Mtwo R files (25/0.05 and 15/0.05) were used in groups A2 and B2. The time required to extirpate the root filling was also recorded. After retreatment, another CBCT scan was taken at the same position. The volume of remaining filling materials inside the canals was calculated before and after retreatment. The data was analyzed using the two-way ANOVA and independent t-test., Results: The remaining filling materials in the canals treated with ProTaper were less than Mtwo. The remaining volume of GuttaFlow was less than gutta-percha regardless of the system applied. Mtwo R files removed root fillings faster than ProTaper R., Conclusion: ProTaper R removed filling material more efficiently compared to Mtwo R which required less time to remove root filling material.

Objectives: The aim of this study was to compare apical sealing ability of alpha and beta phases of gutta-percha by means of bacterial leakage model., Materials and Methods: Fifty single-rooted human premolars were selected. The root canals were prepared with Mtwo rotary instruments up to apical #35.04. Forty teeth were randomly divided into two groups (n= 20). The root canals were obturated by alpha phase (G1) and beta phase (G2) of gutta-percha and AH26 sealer, respectively, with warm vertical compaction technique. Ten teeth served as positive (n=8) and negative (n=2) control groups. Then, the specimens were sterilized with ethylene oxide gas. Bacterial suspension of Enterococcus faecalis (E. faecalis) in 0.5 McFarland concentration was prepared. All teeth were mounted in plastic vial caps containing Muller Hinton broth and then exposed to bacterial suspension of E. faecalis every three days up to 31 days. The number of days required for the contamination of the entire root canals was recorded. The data were analyzed using Mann Whitney U test., Results: There were no significant differences in bacterial leakage between the G1 and G2 groups (P>0.05). Negative controls revealed no microbial leakage; whereas positive controls showed gross microbial leakage., Conclusion: Despite better thermal conduction and adaptability of alpha phase of guttapercha, our study revealed no significant difference in bacterial leakage between alpha and beta phases of gutta-percha in warm vertical compaction.

Objectives: This study aimed to assess the radicular wall thickness in mandibular incisors with two canals and find the maximum and minimum thickness to prevent root canal treatment (RCT) procedural errors., Materials and Methods: A total of 160 extracted mandibular incisors were selected and radiographed; out of which, 55 had two canals. Three parallel transverse sections were made in each tooth at 1mm below the cementoenamel junction (CEJ), mid-root and 1 millimeter to the apex. Specimens were evaluated under a stereomicroscope and the thickness of radicular walls in each section was determined for the buccal, lingual and proximal surfaces. Data were statistically analyzed using Pearson's correlation coefficient test., Results: The thickness of radicular wall decreased from the cervical towards the apex. In all three sections (cervical, mid-root and apical), the thickness of lingual wall was significantly greater than the buccal wall. Also, the thickness of buccal and lingual walls was significantly higher than that of the proximal walls., Conclusion: The lingual radicular wall had the highest thickness in two-canal mandibular incisors. Therefore, in these teeth, the lingual canal is a better choice for post placement.

Objectives: This study aimed to assess the effect of chloroform, eucalyptol and orange oil solvents on the microhardness of human root dentin., Materials and Methods: Sixty-eight single-rooted single-canal extracted human premolar teeth were used. Tooth crowns were separated from the roots at the cementoenamel junction (CEJ). Roots were buccolingually sectioned into mesial and distal halves. Specimens were randomly divided into 5 groups, with 20 teeth in each solvent group and 4 teeth in each control group. Primary microhardness of specimens was measured using Vickers microhardness tester. Specimens were exposed to solvents for 15 minutes and were subjected to microhardness testing again. Data were recorded and analyzed using repeated measure ANOVA., Results: No significant difference was found in dentin microhardness before and after exposure to solvents in any of the orange oil, eucalyptol, chloroform or saline groups (P=0.727). None of the experimental groups showed any significant difference in terms of dentin microhardness reduction (P=0.99) and had no significant difference with the negative control group., Conclusion: This study showed that chloroform, eucalyptol and orange oil as gutta percha solvents did not decrease the microhardness of root dentin. Thus, none of the mentioned solvents has any superiority over the others in terms of affecting dentin properties.

Objectives: This study was performed to evaluate the cytotoxicity of four calcium silicate-based endodontic cements at different storage times after mixing., Materials and Methods: Capillary tubes were filled with Biodentine (Septodont), Calcium Enriched Mixture (CEM cement, BioniqueDent), Tech Biosealer Endo (Tech Biosealer) and ProRoot MTA (Dentsply Tulsa Dental). Empty tubes and tubes containing Dycal were used as negative and positive control groups respectively. Filled capillary tubes were kept in 0.2 mL microtubes and incubated at 37℃. Each material was divided into 3 groups for testing at intervals of 24 hr, 7 day and 28 day after mixing. Human monocytes were isolated from peripheral blood mononuclear cells and cocultered with 24 hr, 7 day and 28 day samples of different materials for 24 and 48 hr. Cell viability was evaluated using an MTT assay., Results: In all groups, the viability of monocytes significantly improved with increasing storage time regardless of the incubation time (p < 0.001). After 24 hr of incubation, there was no significant difference between the materials regarding monocyte viability. However, at 48 hr of incubation, ProRoot MTA and Biodentine were less cytotoxic than CEM cement and Biosealer (p < 0.01)., Conclusions: Biodentine and ProRoot MTA had similar biocompatibility. Mixing ProRoot MTA with PBS in place of distilled water had no effect on its biocompatibility. Biosealer and CEM cement after 48 hr of incubation were significantly more cytotoxic to on monocyte cells compared to ProRoot MTA and Biodentine.

Objectives: To compare the mechanical properties of Resilon and gutta-percha cones after storing at three different temperatures., Materials and Methods: One-hundred standardized size 40/02 gutta-percha cones and 100 Resilon cones were randomly divided into four groups. The first group of the materials were tested immediately after receipt as the control group. The other three were stored in their packages at -12°C, 4± 1°C and 22± 2°C for three months. Then, obturating cones were loaded by a tensile force at the rate of 5mm/min. Physical integrity of gutta-percha and Resilon cones were also evaluated according to ISO6877. The data were analyzed by one-way analysis of variance, post hoc and t-test. A p-value <0.05 was considered significant., Results: The elasticity modulus of gutta-percha reduced significantly after three months storage at -12°C, while storage at 4±1°C and 22± 2°C had no effect on its modulus of elasticity. In addition, the tensile strength of gutta-percha did not change after three months of storing. The modulus of elasticity of Resilon reduced significantly in all storage conditions; however, its tensile strength did not change. The storage conditions did not have a significant effect on the elongation rate of gutta-percha and Resilon. Eighty percent of gutta-percha cones lost their physical integrity after storage in 4 °±1C and 22±2°C. However, storage conditions had no impact on the physical integrity of Resilon cones., Conclusion: Storing gutta-percha at -12°C can benefit its properties, while keeping Resilon at both refrigerated and room conditions can preserve its mechanical properties.

Objective: Handling of endodontic sealers is greatly dependent on their elasticity and flow ability. We compared the viscoelastic properties of three root canal sealers., Materials and Methods: AH Plus (Dentsply, De Trey, Konstanz, Germany), Endofill (Dentsply Hero, Petrópolis, Rio de Janeiro, Brazil) and AH26 (Dentsply, De Trey, Konstanz, Germany) were mixed according to the manufacturers' instructions. The resulted pastes were placed on the plate of a rheometer (MCR 300, Anton-Paar, Graz, Austria). The experiments were performed at 25°C and 37°C. Viscoelastic properties of the sealers including loss modulus (G″), storage modulus (G') and complex viscosity (η*) were studied using dynamic oscillatory shear tests. The shear module versus frequency (from 0.01 to 100 S(-1)) curves were gained using frequency deformation sweep test. Three samples of each material were examined at each temperature. The mean of these three measurements were recorded., Results: The storage modulus of AH plus was higher than its loss modulus at two temperatures. Endofill exhibited a crossover region in which the storage modulus crosses the loss modulus in both temperatures. At 25°C the loss modulus of AH26 was higher than the storage modulus (G″>G'). In contrast, at 37°C G' was greater than G″ (G'>G″). Both shear modules of AH Plus and Endofill decreased as the temperature raised from 25°C to 37°C. On the contrary, the loss modulus and storage modulus of AH26 increased at 37°C., Conclusion: In both test temperatures, AH Plus behaved like viscoelastic solids and Endofill exhibited a gel-like viscoelastic behavior. AH26 at 25°C behaved like liquids, while at 37°C it was an elastic solid-like material.

Introduction: There is some controversy about the effect of enamel matrix derivative (EMD) on inflammation and resorption. The aim of this study was to investigate the effect of EMD on the inflammatory response of monocytes and their phagocytic activity in vitro., Methods: Human monocytes were incubated in complete medium (CM) and exposed to 50, 100, and 200 microg/mL EMD for different time points (12, 24, 48, and 72 hours). Untreated monocytes were considered as controls. Cellular viability was evaluated through a 3-(4, 5 dimethylthiazol-2-yl) 2, 5-diphenyl-2 tetrazolium bromide assay. For cytokine measurements, the cells were treated simultaneously with 50, 100, or 200 microg/mL EMD and 10 microg/mL Escherichia coli lipopolysaccharide. Cell-free supernatants were collected after 12, 24, 48, and 72 hours of incubation. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) concentrations were measured by an enzyme-linked immunosorbent assay kit. Phagocytic activity of the cells was assayed using the PHAGOTEST kit (Glycotope Biotechnology, Heidelberg, Germany) according to the manufacturer's instructions., Results: The viability of cells exposed to 50, 100, and 200 microg/mL EMD for 12, 24, 48, and 72 hours were similar to the controls. There was no significant differences in the production of TNF-alpha and IL-1beta among samples with various concentrations (50, 100, and 200 microg/mL) of EMD and control (EMD = 0) at 12, 24, 48, and 72 hours. Phagocytic activity of monocytic cells increased significantly after 72 hours compared with 12 hours., Conclusions: Based on the results of this study, EMD does not promote releasing of the two studied proinflammatory and resorbing cytokines, TNF-alpha and IL-1beta. By increasing the phagocytic activity of monocytic cells, EMD might accelerate wound healing., (Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Successful endodontic treatment is dependent on a perfect knowledge of normal root canal anatomy and variations from the norm. This study was aimed to investigate the root canal anatomy of mandibular first premolars by both radiography and cross-sectional methods in an Iranian population., Methods: Two hundred seventeen extracted human mandibular first premolars were used. Radiographs were taken in both mesiodistal and buccolingual directions for each premolar. Then, all the teeth were decoronated at the cementoenamel junction and resected perpendicular to their long axes into three equal sections and stained with fuscin. Digital photographs of the cross-sectional root surfaces were taken and surveyed at 40x magnification. The root canal configuration types were determined separately by radiographs and cross-sectional images for each premolar., Results: Out of 217 teeth examined, 192 (88.47%) had a single root canal. The remaining 25 teeth (11.53%) showed two canals in at least one cross-section of their roots with five root canal configurations. In the mesiodistal (MD) radiographs, only 5.99% of premolars showed two canals with three root canal configurations., Conclusions: One-hundred ninety two out of 217 premolars showed one canal in both cross-section and MD radiography. Only 7 premolars were diagnosed as having more than one canal with the same canal configuration in both cross-sections and MD radiography methods., (Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: It has been demonstrated that organic content of the root canals can influence the antimicrobial capability of chemical irrigants. The aim of this study was to evaluate the effect of bovine serum albumin (BSA), as an organic material, on the antimicrobial activity of several intracanal irrigants., Materials and Methods: Bactericidal activity of Ethylenediaminetetraacetic acid (EDTA) 17%, citric acid 10%, Sodium hypochlorite (NaOCl) 5.25%, Chlorhexidine 0.2% (CHX), Smear Clear and Cetrimide 0.5% were tested by means of dilution-neutralization method. Contact times were 10 and 30 seconds, 5, 10, 30, 60 minutes and 24 hours. First 950 λ of the medicament was mixed with 50 λ of the bacterial suspension in an Eppendorf test tube. The suspensions were thoroughly mixed. Sterile water served as negative controls. After each contact time, 100 λ of samples was transferred to the Eppendorf test tubes which contained neutralizers. After 5 minutes, 50 λ of serial dilutions were cultured on brain heart infusion agar and incubated in aerobic conditions. Then colonies were counted and reported as cfu/mL. In half of the samples, medicaments were suspended in BSA 0.5% 30 minutes before examination to assess its possible inhibitory effect on the antibacterial activity., Results: NaOCl 5.25%, Cetrimide 0.5% and Smear Clear showed bactericidal activity within seconds after the incubation. BSA had no inhibitory effect on bactericidal activity of these three medicaments. CHX took 5 and10 minutes to kill all bacterial cells in the absence and presence of BSA, respectively. Citric acid and EDTA showed the least antibacterial activity., Conclusion: In this study, NaOCl 5.25%, Cetrimide 0.5% and Smear Clear were significantly more effective against E. faecalis than EDTA 17% and citric acid 10% in the presence and absence of BSA. Also, in the presence of BSA, bactericidal activity of CHX 0.2% against E. faecalis was significantly more than EDTA after 10 and 30 minutes of contact time. EDTA and citric acid showed the least bactericidal activity. [Iranian Endodontic Journal 2009;4(4):139-43].

The purpose of this study was to compare the efficacy of SmearClear (Sybron Endo, Orange, CA), 17% EDTA, and 10% citric acid in smear layer removal. Forty-eight extracted single-rooted human teeth were randomly divided into 4 groups (n = 12) and instrumented using Mtwo nickel-titanium rotary instruments. Each canal was subsequently irrigated with one of the following solutions: 5.25% NaOCl (control), SmearClear, 17% EDTA, or 10% citric acid. After that, all the specimens were subjected to irrigation with 5.25% NaOCl. The teeth were then processed for scanning electron microscopy (SEM), and the removal of the smear layer was examined in the coronal, middle, and apical thirds. The results showed that there were no significant differences in the efficacy of three chelating agents at all levels of the root canals. The comparison of three one thirds in each group showed no significant difference in the SmearClear and EDTA groups. However, the efficacy of citric acid was significantly less in the apical third compared with the coronal and middle thirds of the canals. In conclusion, the protocol used in this study was not efficient to completely remove the smear layer especially in the apical third of the canal.

Introduction: The aim of this study was to compare the cleaning efficacy of three irrigants used during and after instrumentation., Materials and Methods: Eighty-four single rooted human teeth were randomly divided into 7 groups, 12 cases each, and canals were instrumented with Mtwo rotary systems. 5.25% sodium hypochlorite, Smear Clear and 17% EDTA were used for irrigation of the canal during and/ or after instrumentation. After completion of instrumentation, all canals were dried with paper points and prepared to examine by scanning electron microscope. All SEM photomicrographs were scored at the coronal, middle and apical thirds of canals in each group. The data were statistically analyzed using Mann-Whitney and Kruskal-Wallis tests., Results: In the group irrigated with Smear Clear alone, the coronal thirds of the canals were significantly cleaner than middle thirds (P=0.013) and apical thirds (P=0.028). There were less smear layer in the coronal thirds compared to apical thirds (P=0.047) in the group irrigated with Smear Clear and NaOCl alternately .There were significantly more smear layer in the apical thirds compared to coronal thirds (P<0.001) and middle thirds (P=0.007) in the group that Smear Clear and NaOCl were used as final irrigations. There was not any significant difference between three-thirds of the canals in other groups. Comparison of the all groups showed a statistically significant difference (P<0.001) in the amount of debris and smear layer remaining at all three levels of the canals., Conclusion: The findings of this study suggested that a final rinsing by combination of a chelating agent like EDTA or Smear Clear and NaOCl is necessary to obtain favorable clean wall of root canals.

Introduction: Recently, attention has been drawn to the influence of smear layer removal on apical seal, and the relation of root canal filling material with canal wall surface in the presence and absence of the smear layer. The purpose of this study was to evaluate the influence of the smear layer removal on the apical sealing ability of AH26 sealer., Materials and Methods: Forty extracted human anterior teeth were used in this study. All teeth were decoronated at CEJ. Root canals were prepared; and before obturation, they were randomly divided into two groups (n=17): Group A in which the smear layer was left intact, and in Group B smear layer was removed. Six roots were served as controls. After obturation, microleakage was measured by the electrochemical method for 30 days with 3-day intervals. Data were then analyzed by using Mann-Whitney test., Results: Based on the results of this study, in the absence of the smear layer, a highly significant decrease of apical leakage was found (P<0.001)., Conclusion: This study showed that the removal of the smear layer can significantly improve the apical sealing ability of AH26 sealer.