Single Root Research Articles

Root characteristics and yield of rice as affected by the cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application

To address the relationships between the amount of nitrogen fertilizer application and the yield of double cropping rice systems, we investigated the effects of a cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application (SDN) on the morphological and physiological characteristics of double cropping rice. Our results indicated that the effects of SDN on the morphological characteristics of the single plant roots of double cropping rice were not significant, but the morphological characteristics of the population roots were largely different. Specifically, SDN significantly increased the morphological indexes of the root population such as root fresh weight, root volume, root number, root length and root dry weight. The effects of SDN on the total root absorption areas and root active absorption areas of the single plants were non-significant, but it dramatically enhanced the total root absorption areas and root active absorption areas of the plant population during the tillering, heading and mature stages. In addition, SDN significantly increased the root bleeding intensity and elevated the soluble sugar and free amino acid contents of root bleeding sap. Compared to the traditional cultivation pattern (CK), SDN significantly increased root bleeding intensity at the heading stage by 4.37 and 8.90% for early and late rice, respectively. Meanwhile, SDN profoundly enhanced the soluble sugar contents of root bleeding sap by 12.85 and 10.41% for early and late rice, respectively. In addition, SDN also significantly enhanced free amino acid content of root bleeding sap by 43.25% for early rice and by 37.50% for late rice systems compared to CK. Furthermore, SDN increased the actual yield of double cropping rice mainly due to the higher effective panicle number and the larger seed-setting rate. The actual yields of early rice under SDN were higher than CK by 9.37 and 5.98% in 2016 and 2017, and the actual yields of late rice under SDN were higher than CK by 0.20 and 1.41% in 2016 and 2017, respectively. Correlation analysis indicated that the significant positive correlations were observed between the majority of the root indexes and the actual yield across the four different growth stages.

Antibacterial Efficacy of Silver Nanoparticles Impregnated Calcium Hydroxide: An in Vitro Study

OBJECTIVE: To compare the in-vitro antibacterial effectiveness in terms of enterococcus faecalis elimination of conventional unmodified calcium hydroxide paste with an experimental calcium hydroxide impregnated with 1% silver nanoparticles. METHODOLOGY: This in vitro study was conducted during the period July 2019 - January 2020 at Materials Research Laboratory, Centralized Resource Laboratory (University of Peshawar) and Pathology Laboratory (Peshawar Medical College). Sixty human premolar teeth having single root with mature apices were obtained. These were distributed into two groups randomly (n=30); experimental group for testing the antibacterial efficacy of calcium hydroxide impregnated with 0.1% by weight silver nanoparticles and the other was used as a control group for testing the antibacterial efficacy of unmodified calcium hydroxide. Dentine specimens (size 4 x 4x 1mm) were prepared from the teeth using slow speed cutting saw machine. Smear layer was removed with EDTA. Specimens were autoclaved to sterilize them. Then each specimen was contaminated with enterococcus faecalis and incubated anaerobically for 24 hours at 37?C. After the application of medicaments, the zone of inhibition was measured and number of viable bacteria were determined using SEM. Statistical significance was calculated using t-test. p<0.05 was taken as significant. RESULTS: After the application of medicament, the zone of inhibition was greater (9.63mm) in experimental group when compared to control group (4mm) (p<0.001). Number of viable bacteria before application of medicament were 239 and 208 while after application of medicament reduced to 90 and 54 in control and experimental groups respectively (p<0.001). CONCLUSION: The addition of silver nanoparticles to calcium hydroxide significantly enhanced its potential to eliminate biofilm of enterococcus faecalis on dentin specimens. KEYWORDS: Silver nanoparticles, Calcium hydroxide, Root canal infections, Root canal medicament.

Analysis of divergent bifurcations in the dynamics of wheeled vehicles

Abstract. This paper presents the bifurcation approach to analyze divergent loss of stability of the symmetric solution of a nonlinear dynamic model in Lyapunov's critical case of a single zero root. Under such a condition, material birth-annihilation bifurcations of multiple stationary states take place. Moreover, the equilibrium surface of stationary states in a small neighborhood of the symmetric solution is a generalized Whitney fold. In the simplest case of a fold peculiarity, the corresponding bifurcation manifold locally coincides with the discriminant manifold of a third-degree polynomial that determines the manifold of stationary states in a small neighborhood of the symmetric solution. An algorithm to construct the corresponding polynomial is introduced. Through the algorithm, the bifurcation manifold is determined, and the conditions for safe/unsafe loss of stability of the symmetric solution are derived analytically. The proposed approach to analyze divergent loss of stability is implemented for a nonlinear bicycle model of a two-axle wheeled vehicle. It represents a further development of Pevzner–Pacejka's well-known graph-analytical method. The paper determines the critical values of constructive parameters that are responsible for safe/unsafe loss of stability of the vehicle's straight-line motion, and it discusses strategies for the bifurcation approach to analyze divergent loss of stability.

On numerical schemes for determination of all roots simultaneously of non-linear equation

In this article, we first construct family of two-step optimal fourth order iterative methods for finding single root of non-linear equation. We then extend these methods for determining all the distinct as well as multiple roots of single variable non-linear equation simultaneously. Convergence analysis is presented for both the cases to show that the optimal order of convergence is 4 in case of single root finding method and 6 for simultaneous determination of all distinct as well as multiple roots of a non-linear equation. The computational cost, basins of attraction, computational efficiency, log of residual fall and numerical test functions validate that the newly constructed methods are more efficient as compared to the existing methods in the literature.

Comparative Evaluation of Smear Layer Removal in Apical Third Using Four Different Irrigants With Ultrasonic Agitation: An In Vitro Scanning Electron Microscopy (SEM) Analysis.

AimThis study aims to compare and evaluate the efficacy of four different irrigating solutions like sodium hypochlorite, ethylenediaminetetraacetic (EDTA), Oxum, and ozonated water with ultrasonic agitation in removing the smear layer in the apical third of root canals using Scanning Electron Microscopy (SEM).Materials and methodsFor the study, 50 freshly extracted human mandibular premolars with single well-developed roots without any curvatures were taken. The teeth taken were decoronated to obtain a uniform working length of 15 mm, and the samples were instrumented using a ProTaper Gold rotary file system (Dentsply Maillefer, Ballaigues, Switzerland) up to F2 size, along with irrigation of 1 ml of 3% sodium hypochlorite (NaOCl) in between instrumentation. The samples were randomly divided into five groups with 10 samples each, according to the final irrigant used. Group I-EDTA 17%, Group II-NaOCl 5%, Group III-Oxum, Group IV-ozonated water, and Group V-normal saline. In all groups, ultrasonic agitation of the irrigating solution was performed using a size 20 file, held passively inside the root canal. Then the samples were flushed with distilled water, dried with paper points, split into two halves, and subjected to SEM analysis. SEM images of the apical third region of root samples were taken at 5000X resolution and scored on a scale of 1 to 4.ResultsStatistical analysis was done using one-way ANOVA followed by Tukey’s post hoc test using software version SPSS software version 17.0 (SPSS Inc., Chicago). The results showed that the 17% EDTA group showed the least smear layer scores when compared to other groups with statistical significance. This was followed by the Oxum group and 5% NaOCl group, whereas the ozone water group and saline control group showed the highest smear layer scores.ConclusionThe present study reveals that the EDTA is the superior irrigant in the elimination of smear layer in root canal treatment. Newer irrigants, such as Oxum, can be used as an alternative to EDTA for smear layer removal while remaining biocompatible with dentin. Whereas ozone can be combined with other irrigants for synergistic action of enhanced antimicrobial property and smear layer elimination in the future.

Root and Canal Morphology of Mandibular Premolars in a Saudi Subpopulation: A Cone-Beam Computed Tomography Study.

Objectives The efficacy of root canal therapy is dependent on a thorough understanding of both normal and aberrant root canal morphology. As a result, the purpose of this study was to use CBCT to characterize the exact root and canal morphology of mandibular premolars in a Saudi subpopulation. Methods The current study included 1000 mandibular premolars (507 first premolars and 493 second premolars) with completely developed roots. CBCT was performed to assess the shape of the roots and to classify the canal anatomy according to Vertucci's classification. The incidence and similarity of the left and right sides, as well as men and women, were investigated. The data were examined using the chi-square test. Results Of the 507 mandibular first premolars analyzed, 484 (95.5%) had one root, whereas 23 (4.5%) had two roots. Of the 493 mandibular second premolars analyzed, 489 (99.2%) had one root, whereas four teeth had two roots (0.8%). There were no statistically significant variations in the number of roots identified across groups (p > 0.05). The most prevalent in mandibular first premolars was type I, accounting for 70.0% (n = 355) of the studied sample, followed by type II (14.2%, n = 72) and type IV (10.1%, n = 51). For mandibular second premolar, type I had the highest incidence (449 (91.1%)), followed by type II (5.7%, n = 28). Conclusion In a Saudi subpopulation, the majority of mandibular first and second premolar teeth had a single root with a type I canal system. On the other hand, numerous roots with various canal classifications were found.

Root and Root Canal Anatomy of Primary Mandibular Central Incisor, Lateral Incisor, and Canine in Indian Children: A Cone Beam Computed Tomography Study.

Background A thorough knowledge of root and root canal morphology in primary dentition is essential for success of endodontic therapy. This information also finds importance in anthropological research in reconstructing human population history. Lack of studies of root and root canal morphology in mandibular anterior teeth prompted us to the present study. Methods A total of 109 extracted primary mandibular incisors and canines were collected, out of which 90 teeth were selected for this study and divided into 3 groups: CI, mandibular central incisor; LI, mandibular lateral incisor; C, mandibular canine. All the sample teeth were scanned using cone beam computed tomography (CBCT). Number of roots, number of root canals, length of root, mesiodistal (MD), and buccolingual (BL) width of canal, shape of canal, and presence of accessory canals were assessed. Collected data were statistically compared using one-way ANOVA and chi-square tests. Results All teeth studied displayed single root with single root canal conforming to type I Vertucci's classification. Root length of CI was significantly shorter than both LI and C, with no significant difference between LI and C. Straight root canals were more common in CI and LI, whereas curved canals were more common in C. S-shaped canals were seen in a few CI and C. BL canal width was more than MD width in all teeth, C showing significantly larger dimensions than both CI and LI. Conclusion This study presents root and root canal characteristics of primary mandibular central incisor, lateral incisor, and canine in children from Indian ethnicity.

Ethical questions arising from Otfrid Foerster’s use of the Sherrington method to map human dermatomes

ABSTRACT Otfrid Foerster (1873–1941) is well known for his maps of human dermatomes. We have examined the history of the development of his protocols for mapping dermatomes by analyzing his lectures and publications from 1908 to 1939, focusing on his Schorstein Memorial Lecture in 1932 and his use of the isolation (Sherrington) method, in which a single dorsal root is spared in a sequence of resections (dorsal rhizotomies). Because of the absence of medical records for Foerster’s patients, we also review eyewitness accounts of his operating technique, his occasional comments on patients, and the issue of consent. There appears to be no medical justification—at that time or currently—for Foerster’s use of the Sherrington method to map dermatomes L1, L5, S1, and S2, and in our view, these results were obtained unethically. Hence, clinicians and researchers who use his maps should acknowledge those whom Foerster exploited in order to produce them.

Evaluating the predictive accuracy of curated biological pathways in a public knowledgebase.

Reactome is a database of human biological pathways manually curated from the primary literature and peer-reviewed by experts. To evaluate the utility of Reactome pathways for predicting functional consequences of genetic perturbations, we compared predictions of perturbation effects based on Reactome pathways against published empirical observations. Ten cancer-relevant Reactome pathways, representing diverse biological processes such as signal transduction, cell division, DNA repair and transcriptional regulation, were selected for testing. For each pathway, root input nodes and key pathway outputs were defined. We then used pathway-diagram-derived logic graphs to predict, either by inspection by biocurators or using a novel algorithm MP-BioPath, the effects of bidirectional perturbations (upregulation/activation or downregulation/inhibition) of single root inputs on the status of key outputs. These predictions were then compared to published empirical tests. In total, 4968 test cases were analyzed across 10 pathways, of which 847 were supported by published empirical findings. Out of the 847 test cases, curators’ predictions agreed with the experimental evidence in 670 and disagreed in 177 cases, resulting in ∼81% overall accuracy. MP-BioPath predictions agreed with experimental evidence for 625 and disagreed for 222 test cases, resulting in ∼75% overall accuracy. The expected accuracy of random guessing was 33%. Per-pathway accuracy did not correlate with the number of pathway edges nor the number of pathway nodes but varied across pathways, ranging from 56% (curator)/44% (MP-BioPath) for ‘Mitotic G1 phase and G1/S transition’ to 100% (curator)/94% (MP-BioPath) for ‘RAF/MAP kinase cascade’. This study highlights the potential of pathway databases such as Reactome in modeling genetic perturbations, promoting standardization of experimental pathway activity readout and supporting hypothesis-driven research by revealing relationships between pathway inputs and outputs that have not yet been directly experimentally tested.Database URL www.reactome.org

In Vitro Qualitative Evaluation of Root-End Preparation Performed by Piezoelectric Instruments.

Although the application of ultrasounds in endodontic surgery allows for effective debridement of the root canal, incorrect device setting or inefficient tips seem to generate cracks during root-end retropreparation. The primary aim of this in vitro study was to establish the presence, or absence, of a correlation between ultrasonic root-end preparation and the formation of cracks. The present study was conducted on human teeth, extracted for periodontal reasons. After root canal treatment, roots were resected 3 mm from the anatomical apex by using a high-speed handpiece and carbide burs. The resected teeth were retroprepared by using an ultrasonic tip (R1D, Piezomed, W&H, Bürmoos, Austria), setting the piezoelectric device at maximum power available for the tip. Time required for the retropreparation was recorded. Before and after retropreparation, all roots were photographed under a stereomicroscope and analyzed by two different operators to evaluate: (a) the presence and extension of dentinal cracks and (b) the morphology of root-end preparation. Finally, piezoelectric tips were analyzed by scanning electron microscopy (SEM) to evaluate morphologic changes after use. A total of 43 single roots (33 with one root canal, 10 with two root canals) were treated. Average preparation time was 1 minute and 54 seconds. None of the roots without initial cracks developed new cracks after retropreparation. Quality of the preparation margins was fairly equal among the prepared specimens. None of the piezoelectric tips broke during instrumentation, and SEM analysis showed minimal surface wear of the tips after performing 11 retropreparations. Within the limits of the present study, the tested piezoelectric system does not seem to represent a major cause for root crack formation. Pre-existing cracks may expand after ultrasound root-end preparation.

Morfología inusual de raíz y canales del primer molar mandibular, como indicación de tomografía computarizada de haz cónico: A propósito de un caso endodóntico "fronterizo"

Cone-beam computed tomography (CBCT) is a promising tool in dental practice. CBCT provides three-dimensional images and imaging resolution to be used in endodontics. This enhances the diagnosis of various pathologies. However, guidelines have recommended limiting its use due to overexposure to radiation. This article presents the rare case of a mandibular molar with a single root and canal that benefited from taking a CBCT. A 48-year-old woman is referred for endodontic treatment of the permanent left mandibular first molar. The preoperative radiographic examination showed an unusual canal centered along a single root. Taking a CBCT with the relevant information and the patient’s consent improved her diagnosis and treatment. CBCTs should not be used routinely for these purposes but could be justified in “borderline” cases. This paper discusses its indication and clinical implementation following current recommendations and guidelines.

Apically Extruded Debris during Instrumentation using Different Engine Driven File Systems: A Comparative In Vitro Study

AIM: The aim of the present study was to evaluate and compare the amount of apically extruded debris using three engine driven systems. METHODS: Sixty mandibular premolars with single root were used. The samples were divided into three groups with 20 teeth for each group: group 1 Neolix Neoniti A1 (25, 0.08), group 2 WaveOne GOLD Primary (25.07, red), and group 3 Protaper Next (PTN), using X1 (017/0.04), X2 (025/0.06) files. All files were used to prepare the root canals according to manufacturer instruction. Root canal preparation for each group was done according to manufacturer instructions using 16:1 gear reduction hand piece powered by a torque controlled electric motor. Debris collection was made using apparatus described by Myers and Montgomery. The extruded debris weight was measured by subtracting the weight of the empty Eppendorf tubes from the weight of the debris containing tubes results were statistically analyzed. RESULTS: One-way analysis of variance test revealed that there was statistically significant differences between all the three groups being tested (p < 0.001) showed that apical extrusion of the debris of WaveOne Gold was the least followed by Neolix Neoniti and finally PTN which showed the most apical extrusion of debris with a significant difference between all groups. CONCLUSIONS: WaveOne Gold was found to be the least apical extruded debris system among all groups.

Evaluation of antibacterial effect of silver nanoparticles paste with and without curcumin as intracanal medication

BackgroundThe purpose of the current study was to compare the antibacterial activity of silver nanoparticles AgNPs paste and silver nanoparticles AgNPs with curcumin paste as intracanal medications versus calcium hydroxide Ca(OH)2 paste. Thirty extracted, human teeth with single roots were decoronated and mechanically prepared. After sterilization, roots were inoculated with Enterococcus faecalis for 10 days. Roots were separated into three groups in accordance to kind of intracanal medications used; Group A, silver nanoparticles AgNPs (Nanogate company, Cairo, Egypt). Group B, silver nanoparticles AgNPs with curcumin (Nanogate company, Cairo, Egypt). Group C, calcium hydroxide Ca(OH)2 (Metapaste, META BIOMED). First microbiological samples (S1) were collected from the canal, before insertion of intracanal medication. Intracanal medications were kept in root canals in all groups for 7 days; then second microbiological samples (S2) were collected from the canals after medicament removal. After the colony forming units CFUs have been counted, the data were statistically analyzed.ResultsIn the three tested groups, the highest bacterial count was found in (S1), while the least bacterial count was found in (S2) with statistical significant difference between them.ConclusionsThe effect of AgNPs paste and AgNPs with curcumin paste was superior to Ca(OH)2 paste. AgNPs with curcumin paste had the best antibacterial effect.

“Liquid” Identity and Otherness in the Phenomenon of Religious Alienation: The Loss of Critical Thinking and the “Barter” of the Self in the System of Communion

The “interior space” (Guardini, 1997) is inevitably influenced by the “external space”, which can be the mother, the inter-personal relationships, the local community with all its particular declinations (community of peers, scholastic, academic, working, etc.) or society in general; yet the educational relationship (Kanitsa & Mariani, 2017), in particular in the parental and religious sphere, has the main function of “forming” the pupil, as a child or adult, student, or faithful; in the same way, also the whole society in which one is immersed is understood as an “external environment” which continuously influences the formation of an individual. Indeed, for the purposes of this analysis, is interesting to note what Marcuse writes about the constitution of the “conceptual paradigm” of a society: he warns of the fact that when a society is imbued with a certain ideology, it seems that it is “inhabited” by a paradox; since “Ideologies in particular tend to remain entangled in the dilemmas of the paradox, especially if their metaphysics is anti-metaphysics” (Marcuse, 1999, p. 189). What intervenes as a matrix and “interferes” in the educational process, and so what constitutes the original source from which an education springs out and which, therefore, creates an “educational interference” (Demetrio, 2020, p. 5), is undoubtedly multiple and multi factorial, not reducible to a single root. Precisely for this reason, in this investigation, various paradigmatic educational sources will be taken in consideration, also crossing the Global and Digital (Byung-Chul Han, 2015) dimensions typical of our age, since they act as a “stimulus” and so they are understood as “educating forces”. These “forces” appear to be marked, each internally, by a paradoxical logic: they could be realized, indeed, not only as “educational forces” but also as “alienating forces”. It seems that we face a “power” then, which, taking the place of the authentic and beneficial “religious” or parental “care”, “sets” a new bond of Attachment (Bowlby, 1972, 1975, 1983), capable of emulating some significant aspects of care or relationship, infusing instead, discomfort, pain and, ultimately, alienation. The aim of this study is, therefore, to thoroughly investigate this “inner space of consciousness” (Guardini, 2002, p. 41), when happens that it is “violated”, voluntarily or unconsciously, by those who invade it, giving to an individual, at the same time, identity and the alienation of the identity.

Root tensile strength of terrace hedgerow plants in the karst trough valleys of SW China: Relation with root morphology and fiber content

Root tensile strength is commonly affected by root morphology and fiber content, which combinedly affect the effectiveness of terrace hedgerow on controlling soil erosion in sloping farmland. However, the relationships between these root characteristics are still elusive. This study aimed to compare the root tensile strength, root morphologies, and root fiber contents, and quantify their differences among different plant species. Complete root systems of three terrace hedgerow plant species, i.e., O. bodinieri, V. villosa, and D. lablab L. were sampled for detecting root morphologies and fiber contents at different slope positions on a representative hillslope in karst trough valley. Single root specimens were collected to measure root tensile properties for these three plant species. Results showed that most root morphological parameters were the highest in O. bodinieri, followed by D. lablab L. Three plant species presented the same dominant diameter class as < 1.0 mm, and root volumes as < 1.50 cm3. Cellulose with contents closing to 50% was the main fiber type, and increased significantly linearly with the increasing root diameter in both O. bodinieri and V. villosa. The highest tensile strength and Young's modulus were found in D. lablab L., while the best ultimate tensile force and ultimate elongation were displayed in O. bodinieri. Root diameter showed negative power relationships with tensile strength and Young's modulus, a positive power relationship with ultimate tensile force, and a positive linear relationship with ultimate elongation. Our results will deepen the understanding of the terrace hedgerow functions for controlling soil erosion worldwide.

Single Roots in Deciduous Mandibular First Molars; a rare bilateral occurrence, unveiling morphological diversities

Single Roots in Deciduous Mandibular First Molars; a rare bilateral occurrence, unveiling morphological diversities

Geminated Maxillary Incisors: The Success of an Orthodontic Conservative Approach: 15 Years Follow-Up Study

Tooth gemination is often presented clinically and radiologically as merged crowns or “megadonts” with or without a longitudinal fissure, single root, and a single pulp chamber. The increased mesiodistal width of these teeth results in poor anterior aesthetics, anterior crowding, and incisor rotation. Our aim is to present a conservative non-extraction orthodontic approach that provides both good aesthetics and long-term stability. It aims to achieve extra space to incorporate the megadonts into the dental arch and to exceed “super” class I dental relationships. Accordingly, this study shows that geminated teeth were successfully retained by means of conservative non-extraction orthodontic mechanotherapy and without premolar extractions or enamel reduction. It demonstrated stability during a long-term 15-year follow-up, in addition to high patient satisfaction, good aesthetics, and periodontal health. The solution protocol is definitive and achieved the aesthetic, psychological, and functional objectives at a feasible cost. Thus, this treatment has proven to be preferable to other alternative surgical prosthodontic and endodontic approaches in terms of its long-term stability, and by providing a solution that does not necessitate further multidisciplinary interventions. Dental practitioners in the fields of pediatric dentistry, endodontics and prosthodontics should be well aware of this option.

Amharic Adhoc Information Retrieval System Based on Morphological Features

Information retrieval (IR) is one of the most important research and development areas due to the explosion of digital data and the need of accessing relevant information from huge corpora. Although IR systems function well for technologically advanced languages such as English, this is not the case for morphologically complex, under-resourced and less-studied languages such as Amharic. Amharic is a Semitic language characterized by a complex morphology where thousands of words are generated from a single root form through inflection and derivation. This has made the development of Amharic natural language processing (NLP) tools a challenging task. Amharic adhoc retrieval also faces challenges due to scarcity of linguistic resources, tools and standard evaluation corpora. In this research work, we investigate the impact of morphological features on the representation of Amharic documents and queries for adhoc retrieval. We also analyze the effects of stem-based and root-based text representation, and proposed new Amharic IR system architecture. Moreover, we present the resources and corpora we constructed for evaluation of Amharic IR systems and other NLP tools. We conduct various experiments with a TREC-like approach for Amharic IR test collection using a standard evaluation framework and measures. Our findings show that root-based text representation outperforms the conventional stem-based representation on Amharic IR.

Evaluation of microleakage of three different endodontic sealers in the presence and absence of moisture

Background and aims: AH26, Master-Dent, and Endoseal mineral trioxide aggregate (MTA) are three different types of sealers. The purpose of this study was to assess and compare THE apical seal of the root canal-treated teeth with the above-mentioned sealers in the presence and absence of moisture using the fluid filtration method. Methods: To this end, 54 freshly extracted single root canal human canines were selected for this study. The canals were prepared using rotary instruments, and then sodium hypochlorite was applied as an irrigation solution in this protocol. The specimens were randomly divided into three groups of 18. One group was obturated with the gutta-percha by the cold lateral compaction technique. Half of one of the aforementioned sealers belonged to the group of moistened teeth and the other half to the group of the dried teeth. Microleakage in all groups was assessed 3 months after the obturation of canals by the fluid filtration method. The data were analyzed using ANOVA and Tukey’s post hoc tests, and the level of significance was set at P&lt;0.05. Results: The results showed that the minimum and maximum micro-leakage belonged to Masterdent dry (mean leakage = 1.7778 μL/ min/CmH20) and Endoseal-MTA dry (mean leakage = 3.5000 μL/min/CmH20), respectively. All three groups of sealers exhibited a significant difference in apical micro-leakage between dry and moist conditions (PMasterdent &lt;0.001, PAH26=0.002, and PEndoseaL-MTA =0.007). Conclusion: The findings of this experimental study demonstrated that Masterdent provided the least apical micro-leakage under dry conditions while Endoseal-MTA had the highest micro-leakage under these conditions. There was a significant difference between dry and moist conditions in all groups.

Comparison of the Bond Strength of Circular and Oval-Shaped Fiber-Reinforced Composite Posts in Oval Shaped Canals

Background: Fiber reinforced composite resin (FRC) posts are used to restore endodontically treated teeth. Many factors affect the bond strength of posts; however, there is a concern regarding the mismatch between the posts and oval root canals and its effect on posts retention. Aim: To compare the bond strength of circular and oval-shaped fiber-reinforced composite posts in oval shaped canals. Materials and Methods: Forty Five extracted single rooted human premolars with single oval-shaped root canals were decorated, endodontically treated and prepared to receive quartz reinforced composite resin posts, then they were randomly assigned to three groups, the posts in the first group (control) (n=15) were parallel with circular cross section (Match post, RTD, France), the posts in the second group (n=15) were taper with circular cross section (DtLight Illusion post, RTD, France), The posts in the third group were oval shaped (Macro lock oval post, RTD, France). The posts in the three groups were cemented with dual cure resin cement (Permflo DC Composite Luting, Ultra dent, USA). All samples were then stored in 100% relative humidityat at room temperature for 24 hours then pull-out test was performed and data were analyzed using one-way analysis of variance (ANOVA) followed by Bonferonni's post hoc test (a = 0.05). Results: Oval shaped posts showed higher bond strength values than circular posts, whether the circular posts were conical(taper)or parallel (control) (p&lt;0.05).Conclusions: The bond strength of fiber reinforced composite resin posts in oval root canals increased when the posts were oval-shaped.